Aonla Technical Bulletin
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Technical Bulletin No. 1
Aonla (Emblica oficinalis Gaertn.): Post Harvest Handling and Processing Technology
Authors Dr. Sunil Pareek Dr. N. S. Rathore Dr. R.A. Kaushik
Department of Horticulture Rajasthan College of Agriculture MPUAT, Udaipur, Rajasthan, India
Sponsored by National Agricultural Innovation Project Indian Council of Agricultural Research New Delhi, India
Aonla or Indian gooseberry (Emblica officinalis Gaertn) is one of the most important non-traditional and underutilized fruits of Indian origin, having immense potentiality of cultivation on marginal or waste lands. It belongs to the family Euphorbiaceae and sub-family Phyllanthoidae. Aonla tree thrive well throughout the tropical and sub-tropical parts of India either found growing wild or cultivated. Aonla is quite hardy, prolific bearer and highly remunerative even without much care. It can be grown easily on calcareous and slightly saline as well as alkaline soils where common fruit crops do not thrive. Aonla is regarded as sacred by Hindus and has great mythological significance. According to Hindu mythology, one day meal is arranged beneath a aonla tree during Kartik (October) when trees are laden with fruits. Hindu religion also prescribe that ripe fruits of aonla be eaten for forty days after fast in order to restore health and vitality known as Kaya Kalp (Benthal, 1946). The fruit is highly nutritive and it is the richest source of vitamin 'C' among fruits after Barbados cherry (Asenji, 1953), which is essentially having antioxidant effect on human beings. The edible fruit tissues of aonla contain about 3 times more protein and 160 times more vitamin ‘C’ as compared to apple (Barthakur and Arnold, 1991). Normally, single aonla fruit contains 20 times more vitamin ‘C’ in terms of antiascorbutic value as two oranges. It contains 500 to 1500 mg of ascorbic acid per 100 g of pulp. This is much more than vitamin ‘C’ content of guava, citrus and tomato fruits. The fruit contains a chemical substance called leucoanthocyanin or polyphenols which retards the oxidation of vitamin ‘C’ and presence of astringency (Sastry et al., 1958; Singh et al., 1993). Hanif et al. (1966) noted marked antioxidant effect of gallic acid present in aonla fruits. Thus, vitamin ‘C’ content of aonla is in no way lower than that of Barbados cherry (Mustard, 1952; Ledin, 1958) from nutritional point of view. The aonla fruit is valued high among indigenous medicines in India. It has been recognized as Amritphal in oldest scriptures (Anonymous, 1952; Chopra et al., 1958). It
is valued as an antiascorbutic, diuretic, laxative (Nadkarni, 1927), antibiotic (Ray and Majumdar, 1976) and acidic, cooling and refrigerant (Singh et al., 1993). Dried fruit is useful in hemorrhage, diarrhea, chronic dysentery, diabetes, jaundice, dyspepsia and cough. Aonla is the main ingredients in chavanprash and triphla. Aonla may be an important fruits of future due to its high medicinal and nutritional value, high productivity per unit area and suitability even in the wastelands particularly in salt affected soils. It has immense scope for processing and value addition as the fruits are not consumed fresh or in raw state as it is highly acidic and astringent. For an underutilized species of its economic stature, the genetic improvement work on aonla is noteworthy. It is a species researched by several research institutions and universities and this has resulted in the development of a large number of varieties, standardization of cultivation practices, post harvest technology and processing. The relevant findings on post harvest management and processing have been used in this bulletin to meet the requirement of research workers, extension workers, growers and processors.
POST HARVEST HANDLING
Post harvest management activities start immediately after harvesting of fruits at proper maturity level. This also includes number of activities such as minimal or primary processing at field level i.e., removing field heat, sorting, grading and packaging for transportation, secondary processing for value addition and finally packaging and marketing. Post harvest management of fruits depends on number of factors such as cultivation and production practices adopted, quantity and quality of fruits obtained after harvesting, size of farm and orchard, expected return and value addition near by if any, etc. Production practices have a tremendous effect on the quality of fruits at harvest and on post harvest quality and shelf life of products. In addition, environmental factors such as soil type, temperature, relative humidity, air flow rate, frost and rainy weather also affect the storage life and quality. The harvest and post harvest management of aonla fruits includes proper maturity indices, washing (removing field heat), sorting and grading, pre treatment or other minimal processing techniques, packaging, storage, transportation and marketing. The detailed description of these steps involved in post harvest handling is given in this chapter. Determination of maturity indices: Harvesting crops at the proper maturity allows handlers to begin their work with the best possible quality produce. Fruits harvested too early may lack flavour and may not ripen properly, while produce harvested too late may be fibrous or overripe ( Kitinoja and Gorny, 1999). It is therefore essential to formulate harvest indices or criteria for harvesting the fruit at the right stage of maturity. Maturity is that stage at which a commodity has reached a sufficient stage of development that after harvesting and post harvest handling, its quality will be at least the minimum acceptable to the ultimate consumer. Horticultural maturity is the stage of maturity at which plant or plant part possesses the prerequisites for use by consumers for a particular purpose (Reid, 2002). Being an underutilized fruit crop, less attention has been given on establishing reliable maturity indices of aonla. However, several parameters like specific gravity, TSS 4
: acid ratio, colour of fruit surface, fiber content, seed colour, heat units, days from flowering to maturity can be used for determining maturity index of particular cultivar of aonla in a particular region (Ojha, 1986; Singh, 1997; Singh et al., 2004). After the fruits have set, the embryo lies in dormant condition and ovary does not exhibit any symptom of external growth until middle of August. The diameter and volume of the fruit increase rapidly thereafter, and the maximum growth is achieved by November after which there is not much increase in size (Bajpai, 1968). Fruits completed almost 70 per cent growth during last week of August to last week of September. On the basis of season of maturity in eastern Uttar Pradesh, aonla varieties have been classified into three groups i.e., early, mid and late season (Pathak et al., 1993). The maturity season of aonla varieties is given in Table 1. Table 1: Maturity season of aonla varieties Early
Kanchan NA-6 NA-9
However, maturity period is affected by various factors such as location, climate, soil types, and other cultivation practices etc. In north Indian arid climatic conditions of Rajasthan and Gujarat, fruits of Agra Bold, NA-7 and Banarasi matures by the last week of October; Francis and Krishna matures by first week of November; Gujarat-1 and Gujarat-2 by middle of November and that of Kanchan and Chakaiya by the last week of November (Singh et al., 2006). Specific gravity increases with the advancement of maturity and at the time of maturity specific gravity should be 1.02 in Chakaiya; 1.03 in NA-7, Krishna and Kanchan; 1.06 in Gujarat-2; 1.07 in Agra Bold and 1.08 in Banarasi, Francis and Gujarat1. Fiber content at maturity is 0.37 per cent in Krishna, 0.38 per cent in Banarasi , 0.54
per cent in NA-7, 0.58 per cent in Gujarat-1, 0.60 per cent in Gujarat-2, 0.65 per cent in Agra Bold, 0.72 per cent in Francis, 0.81 per cent in Chakaiya and 0.84 per cent in Kanchan (Singh et al., 2006). The Fruit colour range from dull greenish yellow to translucent in various cultivars. The fruit skin colour of various cultivars is given in Table 2. Table 2: Fruit skin colour of aonla at maturity Cultivar
Fruit skin colour
Thin, smooth, semi translucent, whitish green to straw yellow
Smooth, whitish green to apricot yellow in colour with red spots on exposed surface
Smooth, thick at upper side and thin at basin, light green in colour
Smooth, light green, strips deep red at pea stage which disappear later on
Smooth, semi translucent, light green in colour
Smooth, semi translucent, yellowish green
Slightly rough, thick and light green in colour
Smooth, semi translucent, light green in colour
Rough, yellowish green with pink tinge
Growing Degree Days (GDD) can also be taken in consideration for determination of maturity. GDD or heat unit summation is determined using daily maximum and minimum temperature considering base temperature of 10oC. Harvesting Method The goals of harvesting are to gather a commodity from the field at the proper level of maturity with a minimum of damage in quality and loss in quantity, as rapidly as possible, and at a minimum cost. Careful harvesting is special consideration in aonla fruit because damaged and spotted fruits are not useful for fresh consumption as well as processed products such as preserve and candy. Fully developed fruits, which show sign 6
of maturity, are harvested at right time. This helps in size gain of remaining fruit. Delay in harvesting results in heavy dropping of fruits particularly in varieties like Banarasi and Francis. It also adversely affects the following year bearing. The method of harvesting is hand plucking of individual fruits by bending the smaller twigs or shaking of twigs but the fruits get damaged in later method while dropping on the ground. These dropped fruits are the source of micro-organisms causing rots during storage to other fruits in lot also. Therefore, aonla should never be dropped from the tree by using tree climber or small stairs. Fruit harvester should have long climb and cotton or jute bags or pads for collecting the fruits. Fruits should be harvested early in the morning or in the evening to avoid the damage due to field heat. Harvested fruits should immediately be stored under shade. Sorting Sorting should be done just after arrival of fruits in the packing house. Sorting of aonla is usually done to eliminate injured, decayed, blemished, over or under sized fruits, or otherwise defective produce before cooling or further handling. These un-marketable fruits are called ‘culls’. Sorting will save energy and money because culls will not be handled, cooled, packed or transported. Removing decaying produce items is especially important since this will limit the spread of infection to other units during handling. Sorting is generally done by manual picking over a running plateform. Washing Aonla fruits require washing immediately after sorting for removing field heat and making suitable for secondary processing. Water remaining on the surface of produce must be removed using an air flow and / or sponge rollers in automated units because residual water may encourage fungal growth. For washing of fruits constant flow of clean water in required quantity is essential. This tank for washing produce is made from galvanized sheet metal, a baffle made of perforated sheet metal is positioned near the drain pipe and helps to circulate water through the produce. Fresh water is added under pressure through a perforated pipe, which helps move floating produce toward the drain end of the tank for removal after cleaning. This removed water can be used for other unproductive work including irrigation.
Grading Grading is essential to meet the standards for produce packed for sale through traditional wholesale markets. Although, more primitive market may not use written grade standards. But the products are sorted and sized to some extent. Aonla may be graded according to weight or diameter. So far proper grading have not been standardized in aonla. Aonla fruits should be graded into three grades as given in Table 3 (Singh et al., 1993). Table 3: Grades of aonla fruits Grade
Large sized fruit according to the variety. Banarasi diameter 4.5 cm and above, free from blemishes.
Small sized fruit having diameter less than 4 cm and free from blemishes.
Defective fruits i.e., blemished scaring and necrotic fruits. The fruits may also be graded on the weight basis (A grade = 50 ± 5 g, B grade =
40 ± 5 g and C grade = 30 ± 5 g). Highest physiological loss in weight (PLW) was observed in C grade fruits followed by B and least in A grade fruits during 8 days of storage period at ambient temperatures. PLW in Francis cultivar was 12.50, 16.00 and 20.50 per cent in A, B and C grade fruits, respectively on 8th day of storage (Table 4), however, it was 6.50, 11.30 and 14.50 per cent in Chakaiya (Table 5). Table 4: Physiological loss in weight (%) during storage of aonla cv. Francis fruits in different size grades Grades
Days after harvest 2
Table 5: Physiological loss in weight (%) during storage of aonla cv. Chakaiya fruits in different size grades Grades
Days after harvest 2
The final destination or utilization of aonla fruits is based on the size, weight and fiber content of fruits. Large sized fruits with 45 ± 5 g weight and low in fibers should be used for preserve, candy and pickle making, while small size fruits with medium to high fiber contents is used in making of medicinal produce i.e., chavanprash. Small fruits with necrosis and blemishes can be used in making trifla and for drying or powder making. Packaging The packaging protect the fruits from injury and water lose, and be convenient for handling and marketing. Packages should also provide information about the product, including the grade, handling instructions, and appropriate storage temperatures when the product is on display. The cost of packaging is important, including whether the container can be recycled or reused. Packaging provides protection from physical damage during storage, transportation and marketing. Packaging also decides cost of transportation and storage of fruits for later use. At present proper packaging is inadequate in case of aonla. Aonla fruits are packed in gunny bags of 50 to 100 kg capacity. These fruits got impact, vibration and compression injuries during transportation in these gunny bags. The corrugated fiber boxes are better as this provides appropriate atmosphere and ventilation inside the box, printable information at low cost and recyclable also. Newspaper lining should be provided inside the CFB cartons. The appropriate size of boxes for 20 kg capacity should be used. Minimum spoilage (16.0 %) was noticed in corrugated fiber board boxes with newspaper liner package followed by CFB boxes with polythene liner (17.0 %), where as it was highest in gunny bag without any liner (30.19 %) after 13 days of storage (Singh et al., 2005a). Singh et al. (1993) conducted an experiment on different 9
package containers of 40 kg capacity during distant rail transpotation, and found that wooden crate with polythene liner is most suitable for packing and long distance transportation of aonla fruits. Per cent weight loss and bruising were minimum in this container as compared to gunny bag. Storage The fruit availability period of aonla is very short hardly 2 to 3 months and during November to mid January aonla fruits available in glut. Therefore, storage of fruits at appropriate temperature is essential to extend the availability period and to stabilize the price in the market. Being an underutilized fruit crop, very little study has been done on low temperature, modified atmosphere and controlled atmosphere storages of this valuable fruit. The shelf life is very short at ambient temperatures and it is differ with various cultivars. Singh and Kumar (1997) stored fully mature aonla fruits at room temperature, modified storage condition, zero energy cool chamber and zero energy plusmodified storage condition. It was found that decay loss was minimum (26.56 %) in modified storage condition on 24th day of storage, whereas it was maximum (48.70 %) in zero energy cool chamber. The fruits may be kept in clod storage for 7-8 days at 0-2oC and 8590 per cent relative humidity. Nath et al. (1992) studied the effect of post harvest treatments on shelf life of aonla fruits with calcium nitrate (1%), GA3 50 ppm and borax (4%) and found that the physiological loss in weight and pathological loss increased with the length of storage period. Calcium nitrate (1%) minimized the weight loss during the storage period and no pathological loss was observed with borax up to 9 days of storage. To enhance the shelf life of aonla fruits of local cultivar, Patel and Sachan (1995) tried calcium nitrate (1%), GA3 (40 ppm), CCC (400 ppm) and kinetin (10 ppm). Fruits were dipped in these solutions, packed in perforated polythene bags and stored at ambient temperature. The physiological loss in weight and rotting per cent increased with the increase in storage period. Calcium nitrate (1%) was the best treatment to minimize the weight loss of fruits. No rotting was observed up to 9 days of storage in kinetin (10 ppm) treated fruits. GA3 (40 ppm) treatment gave better retention of vitamin ‘C’ during storage of aonla fruits.
Singh et al. (2005a) recorded the least physiological loss in weight (2.12 - 16.00 % and 2.15 – 16.34 %) and spoilage loss (2.40 - 15.00 % and 2.50 – 15.60 %) and exhibit 11 days of storage life in fruits treated with calcium nitrate 1.5 per cent + perforated polythene bag, and GA3 100 ppm + perforated polythene bag, while untreated control has 7 days economic life under ambient conditions. The same treatments also show lowest respiratory activity (72.10 – 82.00 mg CO2 kg-1 h-1 and 72.00 – 82.10 mg CO2 kg-1 h-1). Therefore, the fruits treated with 100 ppm GA3 or 1.5 per cent calcium nitrate and kept in perforated polythene bag are effective to retain the fruit quality till the last day of storage under ambient conditions. Singh et al. (2005b) assessed four aonla cultivars viz., NA-7, NA-10, Krishna and Chakaiya for their shelf life at ambient condition (18 ± 2oC and 65 ± 5% RH). In general, the aonla fruits showed browning of skin followed by loss of glossiness after harvest during storage. Among cultivars, Krishna and NA-10 were more prone to browning than NA-7 and Chakaiya. The cumulative physiological loss in weight, TSS, acidity and tannins increased, while ascorbic acid content decreased on prolonging the storage period in all the cultivars. NA-10 and Krishna exhibited minimum loss in weight, rich in TSS, ascorbic acid, tannins than Chakaiya and NA-7. Greenness (-a chromacity value) was maintained in cultivar NA-10 and Krishna followed by Chakaiya during storage. Contrary to this, maximum yellowness index (based on L, a and b values) was recorded in NA-7 and minimum in Krishna. However, the cultivar NA-7 exhibited least browning compare to Krishna up to 10 days of storage. Therefore, NA-10 and Krishna have better shelf life of 10 days which retained high vitamin ‘C’ content, glossy and green appearance compared to NA-7 which can be stored for 6-8 days only under ambient conditions. Conclusively, due to its perishable nature, it is difficult to store aonla fruits for long duration or transport over long distances. In order to have good income from aonla, it must be sold immediately in the market. But, the problem arises when there is glut in the market. To get profit during that period, proper storage facilities should be available to help the farmers in getting maximum profit. The extension of shelf life during storage should be made possible by checking the rate of respiration, transpiration and microbial
infection. Plant growth regulators, certain chemicals, fungicides, and low temperatures have played a great part for short period storage.
PROCESSING Anola becomes ready for harvesting from mid November to first week of January. The produce remains in the market for a very short span. Since, it is a perishable commodity it needs quick disposal. Huge harvest of produce during peak harvesting season creates glut and the growers are compelled to sale their produce at low prices. Besides, aonla is not consumed fresh or in raw state as it is acidic and astringent. It is therefore not popular as table fruit. The excellent nutritive and therapeutic value offer great potentiality for processing it into several quality products i.e., preserve (murabba), squash, candy, jelly, jam, syrup, pickle, chutney, preserved pulp, blended beverage, carbonated drinks, RTS, supari, churan, powder, barfi, laddoo, segments in sugar syrup etc. The post harvest losses in aonla vary from 30-40 per cent due to its perishable nature and glut during harvesting time, which reduce the market value of the fruit. Hence, value addition through processing would be the only effective tool for economic utilization of increased production of aonla in future.
Traditional and modern methods of processing Aonla has been in use for pickle and preserve since ages in India and the methods employed were based on traditional knowledge of grandmothers. Besides aonla has been an important ingredient for chavanprash, a ayurvedic health tonic. The methods used previously were unhygienic in nature and time consuming. The nutritive loss in these methods was higher. The manual methods are costly, laborious and cannot maintain quality of the products. Minor accidents have also been reported during manual pricking and shredding and the shelf life of the prepared products was also less and the quality not up to the mark. The modern methods for preparation of different aonla products are hygienic, consume lesser time and provide maximum retention of nutrients especially vitamin ‘C’. The processes for preparations are standardized with proper preservation. There is an urgent need to design matching processing equipment such as grader, segment separator, pricking machine, shredder, etc., to develop a complete pilot plant. The engineering input
in terms of machines will improve its quality as per international standards so that products can compete in the international market (Goyal et al., 2008). Aonla products: An over view Aonla fruits are normally used to make preserve. A preserve is made from fully matured aonla fruits by cooking it whole or in the form of large pieces in heavy sugar syrup, till it becomes tender and transparent. Freshly made preserve is wholesome and have an attractive appearance. When stored for a long period, natural colour and flavour deteriorate on account of oxidative changes. They should therefore, be made only during the season unless there are adequate facilities to store the fruits so that they are available in the off season as well. Although aonla preserve is quite popular, no proper attention has yet been given for preparation of other products like jam, squash, candy, toffee, barfi, laddoo, and preserved pulp of aonla fruits. Candy is an intermediate moisture food which is prepared after shade drying of drained fruits impregnated with cane sugar or glucose. Like other fruits, aonla can also be processed into good quality pulp. This can be used as base material for preparations of different products i.e., squash, syrup, jam and nectar. Thus, there is an overriding need to develop and popularize several other value added products of aonla in view of the increase in the production. Availability of different products of aonla in the market will also be served different categories of the consumers to select the aonla product of their own choice. This in turn will benefit not only consumer, but also aonla growers and processors by ensuring better economic returns. Various studies suggests that many types of value added products of aonla can be prepared and a great potential exist for better utilization of aonla than against its present limited use in the from of preserve, chavanprash and triphla. However, more attempts are needed to standardize the procedures for preparation of various new value added products and to assess the suitability of aonla cultivars for preparation of these products. Also removal of astringency from aonla fruits is important step prior to the preparation of various value added products. At present different ingredients or chemicals such as salt, alum and lime are used to remove the astringency in aonla However, very little information is available with regard to their comparative effectiveness in the removal of astringency from different aonla cultivars.
Varietal screening for aonla processing Processed products of good quality can be made only from good quality raw material hence verietal selection is one of the important factors which affects the quality of fruit products. Singh (1984) reported that aonla, fig and ginger are ideally suited for making of candy. Singh and Pathak (1987) evaluated five varieties of aonla for processing based on their physico-chemical properties and organoleptic quality. Out of these five varieties Kanchan and Krishna were suitable for candy and jam. Banarasi was suitable for drying and Chakaiya was suitable for pickle, chutney and syrup. Bhagwan Deen (1992) observed that NA-9 was ideal variety for candy making. Singh et al. (1993) also reported that NA-6 is an excellent variety of aonla for making good quality candy. Nath and Sharma (1998) reported that Chakaiya cultivar is good for making nectar, squash, syrup and jam products. Whereas, Banarasi cultivar is better for candy and pickle preparation. Nath (1999) observed that Chakaiya was suitable for beverages (nectar, squash and syrup) and jam whereas Banarasi was better for candy and pickle preparation. Singh et al. (2004) evaluated five varieties viz., NA-6, NA-7, NA-10, Kanchan and Chakaiya for fruit processing. The variability examined in physico-chemical composition of aonla cultivars indicated the possibility of selecting a variety or cultivars suitable for processing. NA-6 recorded lowest content of fiber, higher content of pulp and total soluble solids with moderate fruit size and ascorbic acid content, while NA-7 showed average physico-chemical composition with higher content of ascorbic acid. These varieties have also higher productivity and fruits are free from necrosis or internal browning, hence they seem to be ideal varieties for processing. Physico-chemical composition of aonla cultivars is given in table 6 and 7, respectively. Table 6: Physical composition of aonla varieties Varieties
Average fruit weight (g)
CD at 5%
Table 7: Chemical composition of aonla varieties Varieties
Ascorbic acid (mg 100g-1)
Phenol (mg 100g-1)
CD at 5%
Referece: Singh et al. (2004)
Effect of pricking, soaking and blanching treatment on quality of aonla products Ascorbic acid plays an important role in human nutrition. The retention of the nutrients in the final products depends on the methods of preparation. Pricking, soaking and blanching of aonla fruits are necessary to render the preserve and candy soft and to facilitate uniform absorption of sugar (Kalra, 1988). There are many reports on losses of nutrients during preparation of candy / preserve in different fruits. The loss of ascorbic acid content during preparation of candy has been observed in aonla (Pathak, 1988; Tripathi et al., 1988; Bhagwan Deen, 1992; Singh, 1997). Sastry and Siddappa (1959) found that prolonged brine treatments of aonla destroy the ascorbic acid content. Ascorbic acid content of aonla preserve decrease during preparation (Sethi, 1980). Sethi and Anand (1982) found that 55.5 per cent ascorbic acid content is lost during preparation of intermediate moisture food aonla preserve (including pricking, soaking and blanching) and only 45.5 per cent ascorbic acid was retained in final product. Tripathi et al. (1988) reported that the aonla candy retained 108.62 mg 100g-1 ascorbic acid as against initial value of 571.76 mg 100g-1 in the fresh fruits. Anand (1970) while studying the effect of certain pretreatments on the loss of tannins and vitamin ‘C’ in aonla preserve found that soaking and blanching of the fruit resulted in heavy loss of these constituents. Damame et al. (2002) reported that unblanched dehydrated products were found to be superior to all the blanched dehydrated products in terms of vitamin ‘C’ retention over a six months storage period. Among the unblanched products, the aonla pulp recorded the highest vitamin ‘C’ content followed by
supari. Among the blanched products the aonla supari treated with 2 per cent salt was found to be superior in vitamin ‘C’ content, aonla candy and preserve to be the most unsuitable sources of vitamin ‘C’. Results indicate that aonla pulp, supari and juice are the most suitable sources of vitamin ‘C’ due to minimum loss of vitamin ‘C’ content during storage. Jain and Khurdiya (2002) observed that blanching of the aonla fruits prior to juice extraction significantly improved the juice recovery, increased the density and tannin content of the juice but reduced the vitamin ’C’ content by 12 per cent. Addition of water increased the juice volume but diluted the juice and reduced the water soluble constituents. Higher water soluble constituents and ascorbic acid contents were obtained by blanching the fruits and separating the segments. The astringency in aonla fruits is due to the presence of poly phenols or tannins which make them unpalatable but they have therapeutic value (Sastry et al., 1958). Due to this astringency the fruit is bitter in taste. Hence, astringency can be removed by curing with either salt or lime. Sethi (1980) recommended blanching of aonla fruits for 4 minutes in boiling water while Sethi and Anand (1983) found that 25 per cent of ascorbic acid and 24.4 per cent of tannins in aonla are lost during blanching. Geetha et al. (2006) observed that blanching done prior to processing of aonla preserve has marked effect on all the physico-chemical constituents of the aonla. Ascorbic acid content during the process of blanching reduced significantly from 563.12 mg 100g-1 (before blanching) to 434.95 mg 100g-1 (after blanching) showing a loss of 19.20 per cent in ascorbic acid. Similarly, TSS, acidity, total sugars, reducing sugars, non-reducing sugars, moisture and pectin content showed a loss of 10.67, 30.78, 4.95, 5.83, 2.45, 2.20 and 21.60 per cent respectively with blanching. Phenolic compounds are important in determining colour and flavour of fruits. The losses of total phenolic compounds during preparation of aonla candy have been reported by Pathak (1988) and Tripathi et al. (1988) as compared to fresh fruit. Sethi and Anand (1982) observed the loss of tannins during preparation of intermediate moisture food of aonla as compared to initial value in fresh fruits. Organoleptically good quality aonla candy was prepared by various workers. Pathak (1988) observed that 2 per cent salt solution soaking of pricked aonla fruits was
organoleptically ideal. Bhagwan Deen (1992) and Singh et al. (1993) observed that organoleptically good quality aonla candy was prepared with 2 per cent salt and alum soaking of pricked fruits each for 24 hours.
Techniques of preparation for processed products of aonla Aonla fruit is sour and astringent in taste, hence it is not popular as a table fruit. The excellent nutritive and therapeutic value of fruit has great potentiality for processing into value added products. Presently aonla fruit has significance in medicinal (Chavanprash, Triphala, Amrit Kalash, Amal Rasayan etc.) and cosmetic (hair oil, shampoo, hair dyes etc.) products. Very little attention has been paid towards the value added food products as these food items can get position in national and international markets. The most suitable recipe determined by organoleptic evaluation for some of the important products is described here.
Pulp extraction technique Nath (1999) carried out a study on the extraction of aonla pulp and suggested a method for preparation of aonla pulp from fully matured fruits. In this process, the fruits are blanched in boiling water for about 10 minutes to separate the segments from stone. Equal quantity of water is added to the segments and in the pulper to make pulp. If the pulp has to be preserved, it should be heated to 75oC and cooled to room temperature. Potassium meta-bi-sulphite (2g kg-1 of pulp) should be mixed thoroughly and the pulp should be filled in clean sterilized bottles and then sealed. The flow chart illustrating extraction of aonla pulp is given in Figure 1.
Matured aonla fruit Washing Heating in boiling water for 10 minutes Separation of segments and removal of seeds Addition of water in ratio of 1:1 Passing through a pulping machine Pulp
Fig. 1. Flow sheet for extraction of aonla fruit pulp This process involves attention for retention of vitamin ‘C’ at the time of separation of segments and removal of seeds. It has been observed that there is approximately 30 to 35 per cent loss of vitamin ‘C’ at the time of heating in boiling water. Recent pulp extraction technique In this method most of unit operations are same as mentioned above, except process for separating segments and removing seeds from fruits. In this method a shreadder machine can be used for removing seeds instead of putting in boiling water for 10 minutes. The flow chart for this technique is shown in Figure 2.
Fully matured aonla fruits Washing for removing field heat and sanitization Shreadder machine
Shreades + addition of water in 1:1 ratio Passing through a pulping machine Pulp
Fig. 2. Flow chart for extraction of aonla fruit pulp through mechanization
Pickle Small sized aonla fruits, which are not suitable for preparation of preserve and other confectionary items, may be utilized for pickle making. To improve upon the texture of the fruit and also to remove astringency brining is important in pickling. The flow chart for preparation of aonla pickle is given in Figure 3. When pickle is ready after few days, store it at room temperature (Fig. 3)
Selection of fruits
Selection of fruits
Blanching for 10 minutes
Treating with salt water
Conversion into segments and seed removal
for few days
Add spices, oil
Draining of moisture (sun drying for 2 hours)
Leave it for few days in sunshine
Mixing with ingredient (fried)
Packing (glass bottles 500 g capacity)
Store it at room temperature
storage at room temperature
Fig. 3. Flow sheet for preparation of pickle.
Premi et al. (2002) standardized the method for preparation of instant oilless pickle from aonla. Two varieties of aonla (Desi and Chakaiya) were used for the preparation of dehydrated oilless pickle. The overall quality of dehydrated pickle made from pretreated segments of Desi variety was better than variety Chakaiya. For curing aonla fruits for pickling, brining along with potassium meta-bi-sulphite was found to be more effective for long term storage than dry salting or other pretreatment for controlling of white specks, better retention of texture and nutrients in both the varieties. The drying rate was faster in pickle made from cured and steam blanched segments of local variety than in other variety. The recipe used for oil less aonla pickle is given in Table 8.
Table 8: Recipe for dehydrated ready-to-use aonla pickle S. No. 1 2 3 4 5 6 7 8 9 10
Ingradients (g) Whole aonla Aonla segments Salt Red chillies Mustard Ginger Onion Garlic Jaggery Cinnamon
Whole fruits 1000 150 10 75 50 150 20 100 10
Segments 1000 150 10 75 50 150 20 100 10
Juice extraction Jain and Khurdiya (2002) standardized a procedure for the extraction of juice from aonla fruits. Blanching the fruits prior to juice extraction significantly improved the juice recovery, increased the density and tannin content of the juice but reduced the vitamin ‘C’ content by 12 per cent. Addition of water increased the juice volume but diluted the juice and reduced the water soluble constituents. Higher soluble constituents and vitamin ‘C’ content were obtained by blanching the fruits and separating the segments. The relative efficacy of 12 different methods of juice extraction is given in Table 9. Among the methods of juice extraction, centrifugal juice extraction recorded higher density, soluble constituents and higher vitamin ‘C’ and tannin contents as compared to crushing and pressing whole or segments of aonla fruits.
Table 9: Effect of different techniques of extraction on the juice yield and quality of aonla juice Juice
Crushing and pressing whole fruits
Crushing and pressing whole fruits with water (1:1) ratio
pressing whole fruits 4
pressing whole fruits with water (1:1) ratio 5
Crushing and pressing fruits segments
Crushing and pressing fruits segments with water (1:1 ratio)
pressing fruits segments 8
pressing fruits segments with water (1:1 ratio) 9
from fruits segments 10
from fruits segments
water (1:1 ratio) 11
from blanched fruits segments 12
from blanched fruits segments with water (1:1 ratio)
Reference: Jain and Khurdiya (2002)
Blended juice Various workers have explored the possibilities of utilizing aonla fruit for the preparation of juice and beverages (Prasad et al., 1968; Singh and Kumar, 1995; Nath 1999; Deka et al., 2001). Although, aonla fruit juice and beverages prepared there from have poor consumer acceptance yet, could be utilized for vitamin ‘C’ enrichment of other fruit juice based beverages. These vitamin ‘C’ rich natural drinks if given due publicity can replace synthetic drinks and overcome the vitamin ‘C’ deficiency in people world over. Deka et al. (2001) conducted different experiments to study the feasibility of blending juices and pulp from lime, aonla, grapes, pineapple and mango in different preparation for the manufacturing of a ready-to-drink fruit juice beverage. The highest sensory scores were obtained with a formulation comprising of 95 per cent lime and 5 per cent aonla juice. Process flow chart for preparation of aonla juice is shown in figure 4. Jain and Khurdiya (2004) conducted an experiment to develop vitamin ‘C’ rich RTS beverages prepared from apple, lime, pomegranate, Perlette and Pusa Navrang grape juice fortified with aonla juice. For juice extraction, aonla fruits were blanched, seed removed manually, and segments were fed to centrifugal juice extractor. The juice was strained and pasteurized at 90oC for 1 minute, filled in sterilized glass bottles, crown corked, and air cooled. Juice from other fruits was extracted using standard methods, and pasteurized as aonla juice. The aonla juice was mixed with each of apple, lime, pomegranate, Perlette, and Pusa Navrang grape juice in the ratio of 0:100, 10:90, 15:85, 20:80, 25:75, 80:70, and 50:50. All the 40 blends were then adjusted with requisite proportion of water, sugar, and citric acid in order to contain 10 per cent juice, 10 per cent TSS, and 0.22 per cent acidity except lime-aonla blend which had 5 per cent juice, 10 per cent TSS, and 0.22 per cent acidity. All the blends were pasteurized at 90oC for 1 minute before packing in sterilized glass bottles of 200 ml capacity. On the basis of overall sensory quality and vitamin ‘C’ content, RTS beverage prepared by blending aonla and Pusa Navrang grape juice in 20:80 ratio was found to be the best. Therefore, if aonla juice is blended with other fruit juices for the preparation of RTS beverages, it boosts their nutritional quality. These fruit juices in turn improve the
acceptability of aonla juice. These natural fruit drinks have great future in developing and expanding the beverage industry in India and overseas.
Selection of aonla fruit
direct extraction of juice
Extraction of juice
Filling in bottles
Fig 4. Flow sheet for preparation of aonla juice
Ready-to-serve (RTS) Various recipes have been standardized for RTS from aonla pulp/juice with or without ginger and spices. However, simple RTS can be prepared by taking 10 per cent pulp and 12 per cent total soluble solids with 0.3 per cent acidity. Juice is extracted separately and sugar syrup of desired strength prepared separately by boiling sugar with
water and adding citric acid towards the end of boiling. Succumb can be removed from the syrup. After cooling of syrup at room temperature, mix the syrup and juice, homogenize, and fill in the bottles and crown corked the bottles. Then bottles are pasteurized in boiling water for 20 minutes, air cooled and stored for use. Flow sheet for preparation of ready-to-serve beverage is given in figure 5. Extraction of juice
Prepare syrup solution (sugar + water + acid)
Cooling syrup up to room temperature
Mixing juice and syrup
Fig. 5. Flow sheet for preparation of RTS
Squash To prepare 15 litres of aonla squash, 3.75 kg pulp should be mix in sugar solution to have a final product having 45.00 per cent juice/pulp, 50.00 per cent TSS, and 1.00 per cent acidity (FPO specifications). The syrup can be prepared by dissolving 8.1 kg sugar
and 120 g citric acid in 4.5 litres of water. Dissolve the sugar and citric acid by heating the solution. Cool the syrup and strain through a thin cloth. Add the juice and mix at properly along with preservative (6 g KMS). Fill the squash in 1 liter bottles and close the lid. Flow sheet for preparation of aonla squash is given in Figure 6. Juice extraction
Prepare sugar syrup (sugar + water + acid)
Cooling of syrup at ambient temperature
Mixing juice with syrup solution
Addition of preservative (KMS)
Filling into clean sterilized bottles
Fig. 6. Flow sheet for preparation of squash
Nectar Nectar can be prepared by taking 10 per cent pulp and 12 per cent TSS with 0.3 per cent acidity and 350 ppm SO2. To prepare 10 litres of aonla nectar, one kg pulp should be mixed in sugar solution. The syrup can be prepared by dissolving 1.2 kg sugar and 20 g citric acid in 7.6 litres of water by slow heating. Remove the solution from flame when sugar is properly dissolved and strain it properly. Add the pulp after cooling the solution. Mix the preservative (1 g KMS) and homogenize it properly. Nectar is filled
in 200ml bottles and crown corked. The flow sheet for preparation of nectar is given in Figure 7. Aonla pulp
Prepare sugar syrup (sugar + water + acid)
Cooling of syrup at ambient temperature
Mixing pulp with syrup solution
Addition of preservative (KMS)
Filling into clean sterilized bottles
Fig. 7. Flow sheet for preparation of nectar
Syrup Syrup from aonla pulp can be prepared according to FPO specifications i.e., 45 per cent pulp, 68 per cent TSS and 1.2 per cent acidity. The procedure for the preparation of syrup is similar to that of squash.
Jam Jam is a product made by boiling fruit pulp with sugar and citric acid to a desirable thick consistency. The ideal fruit jam should have minimum 45 per cent pulp, 68 per cent total soluble solids and 0.5 per cent acidity. Best quality jam can be prepared from the varieties which have low fiber content and more pulp percentage. To prepare aonla jam, first pulp is extracted from the fruit. This pulp mixed with the desired quantity of sugar and citric acid and this mixture is cooked to desired consistency. The end point judged by hand refractometer (68o Brix) or by drop test or sheet test. The recipe contains 1 kg pulp, 1.25 kg sugar and 5 g citric acid. Flow sheet for preparation of jam is given in Figure 8
Mixing with sugar
Addition of citric acid Judging of end point (TSS 68oB) by hand refractometer / drop test / sheet test
Marketing Fig. 8. Flow sheet for preparation of jam
Herbal Jam Singh et al. (2005d) standardized the recipe for preparation of herbal jam. They prepared the different recipes for preparation of 5 kg herbal jam (Table 10). Recipe No.-1 containing 50 per cent aonla pulp, 75 per cent asparagus + 2 per cent ashwagandha extract with 68 per cent TSS and 1-2 per cent acidity was found the best and it was closely followed by recipe No.2 which contained 10 per cent asparagus juice. Herbal extracts added in aonla pulp for preparation of jam improved the medicinal quality and attract the market. The procedure for preparation of herbal jam is exactly same as that of simple jam given in Figure 8.
Table 10: Organoleptic quality of herbal jam prepared from different recipes Aonla Recipes
Asparagus Ashwagandha Sugar Acidity juice (%)
Organoleptic quality Score
Rating Liked very much Liked very much Liked moderately Liked moderately
Reference: Singh et al. (2005). Herbal squash Singh et al. (2005d) standardized the recipe for preparation of herbal squash. Five different recipes with or without asparagus juice and ginger juice were developed (Table 11). Asparagus and ginger juice were mixed with aonla pulp and the remaining procedure was as such followed for simple squash given in Figure 6. A recipe containing 25 per cent aonla pulp, 5 per cent asparagus extract and 2 per cent ginger juice with 50 per cent TSS and 1.2 per cent acidity was found most ideal for preparation of herbal squash
Table 11: Organoleptie quality of herbal squash prepared from different recipes Aonla Recipes
Asparagus juice (%)
Ginger juice (%)
CD at 5%
Liked slightly Liked
much Liked extremely
Candy The flow sheet for preparation of aonla candy is given in Figure 9.
Washing with water
Dipping in 2% salt solution (24 hours)
Washing with water
Blanching in boiling water
Steeping in 50% sugar syrup (24 hours)
Steeping in 60% sugar syrup (24 hours) 31
Steeping in 70% sugar syrup (24 hours)
Steeping in 75% sugar syrup (24 hours)
Drawing of excess sugar syrup
Coating with pectin or sugar
Shade drying up to 15% moisture
Packing in polyethylene pouches
Store in cool and dry place Fig. 9. Flow sheet for preparation of aonla candy A fruits impregnated with can sugar or glucose and subsequently drained and dried is called a candied fruit. Aonla candies are becoming more and more popular because of high acceptability, minimum volume, higher nutritional value and longer storage life. These have additional advantages of being least thirst provoking and ready to eat snacks. Singh and Pathak (1987) reported that aonla fruit can be utilized for making excellent quality of candy or intermediate moisture food (IMF). Pathak (1988) described the technology for preparation of aonla candy. The recipe contained 1 kg aonla fruit, 1 kg sugar and 1.5 kg water. Tandon et al. (2003) studied the effect of blanching and lye peeling on candy preparation. They found that the candy prepared from lye peeled fruits of aonla showed decreased content of ascorbic acid than blanched fruits. The candy prepared from Lakshmi-52, Kanchan and Chakaiya was found the best. However, the effect of the blanching on some of nutritional parameters was less severe than that of lye peeling. Singh et al. (2003) conducted a study to find out the techno-economic feasibility of processing of aonla products of pulp based (jam, squash, sauce) and non pulp based
(candy ). They found that the per litre processing cost of squash and cost of 1 kg candy was much lower than that the cost of 1 litre sauce and 1 kg jam. Singh et al. (2005d) prepared aonla candy with four different recipe viz., whole fruit with sugar coating, segmented fruit with sugar coating, whole fruit with pectin coating, and segmented fruits with pectin coating. Candy prepared from segmented fruit with pectin coating recorded the highest organoleptic score because of most attractive colour and taste, followed by whole fruit candy with pectin coating. Pectin coating improved the quality of candy, hence it has better consumer appeal. The candy prepared from aonla fruit has bright scope for both internal and external market.
Preserve Aonla fruits are normally used to make preserve. A preserve is made from fully matured aonla fruits by cooking it whole or in the form of large pieces in heavy sugar syrup, till it becomes tender and transparent. Improved method for preserve making includes the washing and selected bold fruit are dipped in 2 per cent common salt solution until the green fruit changes to a creemish colour, with replacement of the brine solution on alternate days. The fruits are thoroughly washed, pricked with a stainless steel pricker and then blanched in boiling water for 4 to 5 minutes. Sugar equal to the weight of fruits is sprinkled over the fruit and kept overnight. The next day, boiling is given to the whole mass and syrup is then drained out. The syrup is thoroughly boiled and concentrated by adding more sugar to 55oB strength and mixed with fruit. The following day the fruit are taken out and syrup is concentrated to 75oB by adding sugar and boiling. Aonla fruit are added back and allowed to stand in syrup for couple of days. When the TSS of the syrup stabilizes at around 70oB, the preserve is packed in clean, sterilized, dry glass jars and stored at ambient room temperature away from direct sunlight. The flow sheet for aonla preserve is given in Figure 10.
Fruits Washing Pricking by mechanical pricker Washing with fresh water Soaking in alum and lime Washing with fresh water Blanching (boiling water for 5 minutes) Washing with fresh water Steeping with syrup solution concentrating by adding and boiling (TSS 40, 50 and 60oB for 24 hours) Steeping in TSS 70oB for a week Packing Labeling Storage Fig. 10. Flow sheet for preserve making
Central Institute for Arid Horticulture (CIAH) developed a new modified protocol for preparation of murabba (Anonymons, 2003). Fully matured uniform big size fruits of NA-7, were harvested, selected and cleaned. The fruits were pricked and kept in 2 per cent salt solution for 24 h, again the fruits were washed and subjected to 2 per cent alum solution for 24 h, the fruits were washed thoroughly, sugar syrup were prepared
separately. The fruit are boiled for three minutes and allowed to boil in the syrup solution for another 5 to 6 minutes. In this method when the fruits are boiled along with sugar syrup, the moisture inside were replaced by sugar. The fruits are packed in a container kept for three days, the syrup solution were heated to remove excess moisture drained from fruits. The murabba are packed in container and stored for 8 to 9 months. The advantage over other methods is to repeat change of concentration daily could be avoided.
Segments in syrup The fruits are blanched in boiling water for 6-8 minutes and segments are separated. The segments are dipped for 24 h each in increasing concentration of syrup of 50, 60 and 70oB by adding sugar with boiling and segments are immersed in it and packed in clean jars.
Churan Tandon et al. (2005) standardized the procedure and recipe for preparation of churan from dried aonla powder. The aonla fruits were blanched in boiling water for 6-8 minutes. The segments were separated out into 3-4 pieces and dried in electric dehydrator at 60oC for 6-7 h. The retention of vitamin ‘C’ content after blanching and subsequent drying was found to be 78 and 49 per cent, respectively. The pieces were then ground to powder form and various ingredients mixed. Among fourteen combinations of ingredients tried for churan, two combinations, having 1-5 g ginger and 0.5 g ajwain and 1.0 g ginger and 2.5 g mint apart from other ingredients (100 g aonla powder, 8 g salt, 16 g black salt, 15 g sugar, 3 g citric acid, 2 g black pepper, 1g asafoetida, 1 g tannin and 1 g fennel), were found to be most acceptable. The flow sheet for preparation of churan is given in Figure 11. Matured aonla fruits
Blanching in boiling water for 6 – 8 minutes
Separation of segments
Electrical dehydration at 60oC for 6 to 7 hours
Packaging Fig. 11. Flow sheet for manufacturing churan Since in this process, the retention of vitamin ‘C’ is hardly 50 per cent. Therefore, alternately a ecofriendly option through integration of solar tunnel drying can be employed, which can be designed as per requirement and produces high retention capacity as far as vitamin ‘C’ is concerned in final products. The flow sheet for preparation of churan through this method is given as follow in Figure 12. Aonla fruits Shreadding through machine
Shreads spreading in solar dryer Dried products Grinding into powder Mixing ingradients Packaging in polythene Storage / marketing Fig. 12. Flow sheet for manufacturing aonla churan
Sauce Recipe: Pulp 1 kg, sugar 75 g, salt 10 g, onion 50 g, garlic 5 g, ginger 10 g, red chilli powder 5 g, hot spices 10 g, acetic acid 2 ml and sodium benzoate 0.25 g. 36
Technique: The flow sheet for preparation of aonla sauce is given in Figure 13. Pulp
Mix with 25g sugar
Add extract of onion, garlic, ginger, chillies and hot spices
Add glacial acetic acid and remaining sugar
Testing of end point for desired consistency
Add salt and sodium benzoate
Processing in boiling water for about 20 minutes
Cooling & Labelling
Storing / marketing Fig. 13. Flow sheet for preparation of sauce
Chutney Recipe and technique used: Recipe containing aonla pulp 1 kg, cumin10 g, turmeric powder 3 g, ginger 10 g, black pepper 2 g, sugar 1 kg, fenugreek 100 g, salt 50 g, red chilli powder 2 g, garlic 10 g, mustard 1 g and vinegar 40 ml. The flow sheet for preparation of chutney is given in Figure 14. Fruits
Steam for 15 minutes in pressure cooker
Pass through mixi
Mix with ingredients
Cook the mixture to a desired consistency
Add glacial acetic acid
Filling into glass bottles
Storage Fig. 14. Flow sheet for preparation of chutney
Chavanprash Chavanprash is a health tonic mentioned in Indian system of medicine i.e., Ayurveda. It is prepared by mixing the aonla pulp pest and sugar while cooking. In this
mixture spices and medicinal plants extracts are added for further cooking. Recipe contains the following items Aonla
Shreads and Drying Pragati et al. (2003) conducted an experiment on effect of drying methods on nutritional composition of dehydrated aonla fruit during storage. Aonla fruit cv. Chakaiya was dried using four different methods viz., osmo-air drying, direct sun drying, indirect solar drying and oven drying. The osmo-air drying method was found to be the best method for drying of aonla because of better retention of nutrients like ascorbic acid and sugars. The level of antineutrients like tannins was also found to be lower in osmo-air dried aonla compared to other methods of drying because of leaching. Browning of the dehydrated fruits was also minimal in the case of osmo-air dried fruits. The nutrient content in osmo-air dried aonla was satisfactory after 90 days of storage. The raw and KMS treated samples of Banarasi and Chakaiya varieties were dehydrated by sun and mechanically dried (60oC) for the preparation of aonla powder (Sharma et al., 2002). The processed dehydrated powder was packed in 100 gauge packages of high density polyethylene (HDPE) and low density polyethylene (LDPE). The packages were stored under ambient (5-18oC and 60% RH) and refrigerated (4 + 1oC
and 90% RH) conditions. It was found that the aonla powder prepared from pretreated Chakaiya variety and mechanically dried can be stored effectively in HDPE packages under refrigerated condition for 3 months without much loss in vitamin ‘C’, having better overall acceptability in terms of appearance, taste, flavour and texture. Processes for dehydrated aonla powder have been standardized by Alam and Singh (2005). The pricked aonla fruits were blanched for 5 minutes in 5 per cent boiling salt solution containing 0.15 per cent NaHCO3 and 0.10 per cent MgO. The blanched aonla fruits were sulphited for 30 minutes in 0.5 per cent KMS. The treated fruits were sliced manually with knife. For the dehydration of aonla slices, the mechanical dryer (50, 60 and 70oC), solar and cabinet dryers were used. They found that the mechanically dried slices contained higher in vitamin ‘C’ content and were organoleptically superior to slices dried under solar and cabinet dryer Kavitha et al. (2003) studied the effect of osmotic dehydration on vitamin ‘C’ content of aonla at different salt concentrations and different temperatures. The over all retentions of vitamin ‘C’ was found better in the un-blanched osmotically dehydrated and air dried samples. Drying study of aonla was also conducted by Singh et al. (2006) in a batch type pilot scale solar tunnel dryer (80-85 kg wet product batch) with open sun drying as control. The collector area of the dryer was 25 m2. The dryer is 2.0 m wide, with a 4.5 m solar air heater and a drying tunnel of 8.0 m. The heater and dryer are covered with UV stabilized polyethylene film. Solar photo-voltaic (SPV) operated axial flow fans have been provided at one end to put fresh air to the dryer. The air flow through the tunnel was around 300-600 m3 h-1. Sixty five kg de-seeded blanched aonla pieces were uniformly spread over the drying trays @ 4.75 kg m-2. Initial moisture content of aonla was around 85 per cent. Aonla pieces were dried in the tunnel in five and half days as compare to ten days in open sun drying in the month of October. Average drying temperature in the tunnel and in open was 54.3oc and 36.5oC. The average solar insulation during drying days was 600 Wm2. Moisture content of aonla dried in the tunnel dryer and in open sun were 3.2 per cent and 3.9 per cent, respectively. The quality of the solar tunnel dried aonla was found to be superior in terms of lower bacterial count, better appearance and acceptability.
LITERATURE CITED Alam, S. and Singh, A. 2005. Process for dehydration aonla powder. Abstract presented in Convention of Indian Society of Agricultural Engineers, 39: 222. Anand, J.C. 1970. Effect of pretreatments on the loss of tannins and vitamin C in aonla and aonla preserves. Indian Food Packer, 36: 38-43. Anonymous. 1952. Wealth of India – Raw Materials. Vol. 1.3. CSIR, New Delhi. Anonymous. 2003. Annual Report 2003-04. Central Institute for Arid Horticulture, Beechwal, Bikaner, Rajasthan, India. Pp. 83. Asenji, C.F. 1953. The story of West Indian cherry (Malpighia punicifolia L.). Boletin del colegio de Químicos de Puerto Rico. 10: 8-11. Bajpai, P.N. 1968. Studies on flowering and fruit development in aonla (Emblica officinalis Gaertn.). Horticulture Advances, 7: 38-67. Barthakur, N.N. and Arnold, N.P. 1991. Chemical analysis of the emblic (Phyllanthus emblica L.) and its potential as a food source. Scientia Horticulturae, 47: 99 -105. Benthal, A.P. 1946. Trees of Calcutta and its neighbourhood. Thacker Apink and Co. Ltd., Calcutta. Bhagwan Deen. 1992. Studies on screening pf aonla (Emblica officinalis Gaertn.) genotypes for processing. MSc. (Ag.) Thesis, N.D. University of Agriculture and Technology, Faizabad, UP, India. Chopra, R.N., Chopra, I.C., Handa, K.L. and Kapoor, L.D. 1958. Chopra’s Indigenous Drugs of India. U.N. Dhur and Sons Pvt. Ltd., Calcutta. Damame, S.V., Gaikwad, R.S., Patil, S.R. and Masalkar, S.D. 2002. Vitamin C content of various aonla products during storage. Orissa Journal of Horticulture,
22. Deka, B.C., Sethi, V., Prasad, R. and Batra, P.K. 2001. Application of mixture methodology for beverage from mix fruit juice/pulp. Food Science and Technology, 38: 615-618.
Geetha, N.S., Kumar, S. and Rana, G.S. 2006. Effect of blanching on physicochemical characteristics of aonla. Haryana Journal of Horticulture Science, 35: 67-68. Goyal, R.K., Patil, R.T., Kingsly, A.R.P., Walia, H. and Kumar, P. 2008. Status of post harvest technology of aonla in India – A review. American Journal of Food Technology, 3: 13-23. Hanif, M., Rahman, J., Ahmed, I., Bhatty, M.K. and Karimullah. 1966. The antioxidant factor of aonla fruit. Journal of Science of Research, 18: 61-63. Jain, S.K. and Khurdiya, D.S. 2002. Studies on juice extraction of aonla (Emblica officinalis Gaertn.) cv. Chakaiya. Journal of Food Science and Technology, 39: 515-516. Jain, S.K. and Khurdiya, D.S. 2004. Vitamin C enrichment of fruit juice based readyto-serve beverage through blending of Indian gooseberry (Emblica officialis Gaertn.) juice. Plant Foods for Human Nutrition, 59: 63-66. Kalra, C.L. 1988. The Chemistry and Technology of Aonla : A Resume. Indian Food Packer, 42 : 67-82. Kavitha, C.V., Sreenarayanan, C.T., Devdas and Krishanaven, S.K. 2003. Effect of osmotic dehydration on vitamin C of aonla. Abstract presented in Annual Convention of Indian Society of Agricultural Engineers, 37: 134. Kitinoja, L. and Gorny, J.R. 1999. Post Harvest Technology for Small Scale Produce Marketers: Economic Opportunities, Quality and Food Safety. University of California, Davis, Post Harvest Horticulture series 21. Ledin, R.B. 1958. The Barbados or West Indian cherry. Bulletin No. 594. University of Florida, Agriculture Experiment Station, Gainsville, Florida. Mustard, K.J. 1952. Ascorbic acid content of some miscellaneous tropical and subtropical plants and plants products. Food Research, 17: 31-35. Nadkarni, K.M.1954. Indian Materia Medica. S.K. Bijur, Mumbai. Nath, V, and Sharma, R.K. 1998. Screening of aonla (Emblica officinalis Gaertn.) cultivars for processing. Progressive Horticulture, 30: 67-77. Nath, V. 1999. Delicacies of aonla. Indian Horticulture, 44: 15-17.
Nath, V., Singh, I.S., Kumar, S. and Pandey, A.K. 1992. Effects of post harvest treatments on shelf life of aonla fruits. Progressive Horticulture, 24: 79-82. Ojha, C.M. 1986. Physico-chemical changes during growth, development and storage of aonla (Emblica officinalis Gaertn.) fruits. M.Sc (Ag.) thesis, ND University of Agriculture and Technology, Faizabad, UP, India. Patel, A.B. and Sachan, S.C.P. 1995. Extension of storage life of aonla fruits. Indian Food Packer, 49: 43-46. Pathak, R.K., Srivastava, A.K., Diwedi, R. and Singh, H.K. 1993. Aonla Descriptor. Department of Horticulture, N.D University of Agriculture and Technology, Faizabad, UP, India. Pp. 24. Pathak, S. 1988. Post- harvest technology of aonla (Emblica officinalis Gaertn) fruits. Ph. D. Thesis, N.D. University of Agriculture and Technology, Faizabad, UP, India. Pragati, Dahiya, S. and Dhawan, S.S. 2003. Effect of drying methods on nutritional composition of dehydrated aonla fruits (Emblica officinalis Gaertn) during storage. Plant Foods for Human Nutrition, 58: 1-7. Prasad, P.S.R.K., Surya Prakash Rao, P.V., Nageswara Rao, G. and Girdhar, N. 1968. Some preliminary studies on utilization of aonla ( Phyllanthus emblica Linn.). Indian Food Packer, 22 (6): 8-11. Premi, B.R., Sethi, V., and Bisaria, G. 2002. Preparation of instant oilless pickle from aonla (Emblica officinalis Gaertn.). Indian Food Packer, -: 72-75. Preserve. Indian Food Packer, 24: 16-19. Ray, P.G. and Majumdar, S.K. 1976. Antimicrobial activity of some Indian plants. Economic Botany, 30: 317-320. Reid, M.S. 2002. Maturation and maturity indices. In: Post Harvest Technology of Horticultural Crops (Editor: Kader, A.A). University of California. Pp. 55. Sastry, M.V. and Siddappa, G.S. 1959. Studies on Indian preserves. Food Science, 8: 398-399. Sastry, M.V., Siddappa, G.S. and Lal G. 1958. Chemical and microbial analysis of some important canned preserves. Indian Journal of Horticulture, 15: 26-31.
Sethi, V. 1980. Studies on preparation and storage of some semi dry preserve (Murrabba). Ph.D. thesis, Indian Agricultural research Institute, New Delhi, India. Sethi, V. and Anand, J.C. 1982. Physico- chemical and microbiological quality of carrot and aonla preserves. Indian Food Packer, 36: 38-43. Sethi, V. and Anand, J.C. 1983. Retention of nutrients in carrot and aonla preserve. Indian Food Packer, 37: 64-67. Sharma, S.R., Alam, S. and Gupta, S. 2002. Storage study on dehydrated aonla powder. Abstract presented in Annual Convention of Indian Society of Agricultural Engineers, 35: 155-156. Singh, B.P., Pandey, G., Sarolia, D.K., Pandey, M.K. and Pathak, R.K. 2005a. Shelflife evaluation of aonla cultivars. Indian Journal of Horticulture, 62: 137- 140. Singh, I.S. 1984. Fruit vegetables utilization and preservations (in Hindi). Directorate of Extension, N.D. University of Agriculture and Technology, Faizabad, UP, India. Singh, I.S. 1997. Aonla – An Industrial Profile. N.D. University of Agriculture and Technology, Faizabad, UP, India. Pp17. Singh, I.S. and Kumar, S. 1995. Studies on the processing of aonla fruits. II Aonla products. Progressive Horticulture, 27: 39-47. Singh, I.S. and Pathak, R.K. 1987. Evaluation of aonla (Emblica officinalis Gaertn.) varieties for processing. Acta Horticulturae, 208: 173-177. Singh, I.S., Pathak, R.K., Diwedi, R. and Singh, H.K. 1993. Aonla Production and Post Harvest Technology. Department of Horticulture, N.D. University of Agriculture and Technology, Faizabad, UP, India. Pp.34. Singh, P., Singh, J.P. and Chopra, C.S. 2003. Techno-economic study on processing of aonla products. Beverage and Food World, 30: 68-69. Singh, P.L., Ganesan, S. and Singh, S. 2006. Drying study of aonla (Emblica officinalis Gaertn.) in a solar tunnel dryer. Indian Food Packer, 60: 47-51. Singh, R. and Kumar, S. 1997. Studies on the effect of different storage conditions on decay loss of aonla var. Chakaiya. Haryana Journal of Horticultural Science, 26: 9-12.
Singh, S., Singh, A.K. and Joshi, H.K. 2004. Fixation of maturity standards in Indian gooseberry (Emblica officinalis Gaertn.) under semi arid ecosystems of Gujarat. Proceeding of First Indian Horticulture Congress- 2004 during 6- 9th November, 2004. Indian Agricultural Research Institute, New Delhi. Pp. 341342. Singh, S., Singh, A.K. and Joshi, H.K. 2005a. Prolonging storability of Indian gooseberry (Emblica officinalis Gaertn.) under semi arid ecosystem of Gujarat. Indian Journal of Agricultural Sciences, 75: 647-650. Singh, S., Singh, A.K. and Joshi, H.K. 2005c. Effect of size grading on quality and shelf
life of aonla (Emblica officinalis Gaertn.) cv. NA-7. Proceeding of
National Seminar on Commercialization of Horticulture in Non-traditional Areas, Indian Society of Arid Horticulture, CIAH, Bikaner, during February, 2005. Singh, S., Singh, A.K., Joshi, H.K., Bagle, B.G. and Dhandar, D.G. 2005b. Heat unit summation – an index for predicting fruit maturity in aonla (Emblica officinalis Gaertn.) under semi arid tropics of Western India. Proceedings of 8th Indian Agricultural Scientists and Farmers Congress, B.H.U., Varanasi and Bioved Research and Communication Center, Allahabad, 20-22 February. Pp. 123. Singh, V., Singh, H.K. and Chopra, C.S. 2005d. Studies on processing of aonla (Emblica officinalis Gaertn.) fruits. Beverage and Food World, 32: 50-52. Tandon, D.K., Dikshit, A. and Kumar, S. 2005. Development of churan from dried aonla powder. Beverage and Food World, 32: 53-54. Tandon, D.K., Yadav, R.C., Sood, S., Kumar, S. and Dikshit, A. 2003. Effect of blanching and lye peeling on the quality of aonla candy. Indian Food Packer, 57: 147-149. Tripathi, V.K., Singh, M.B. and Singh, S. 1988. Studies on comparative compositional changes in different preserved products of aonla var. Banarasi. Indian Food Packer, 42: 60-66.