QC test on flour

November 15, 2017 | Author: Fath Bond | Category: Gluten, Flour, Starch, Ph, Wheat
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quality control on flour...





INTRODUCTION Nowadays, there are many types of flour that are available in food industry. It is one of important raw material used to make bread, pastries and many more. There are many way to indicate the quality of flour. One of them is by physical analysis. One of the components that are very important found in flour is gluten. Different flour has different amount of gluten. Gluten is a protein composite found in foods processed from wheat and related grain species, including barley and rye. Gluten is also defined as a cohesive, elastic protein that is left behind after starch is washed away from flour dough. On the other hand, testing the pH of flour is required when it is important to know how much chlorine has been applied. The more chlorine applied, the lower the pH. Usually the pH of the flour falls within the range of 6.0-6.8. However, bleaching flour with chlorine gas will cause a fall in pH value. Meanwhile, kernel hardness also can indicate the quality of the flour where it can affect the amount of starch damaged during the milling process and subsequently the water requirements of the resulting flour. Besides, granular size is also one of the quality parameter for flour. Granulation plays an important role in kneading and also determines the speed at which the dough will rise. Through chemical analysis of flour, ash content is an extremely important measure to know the purity of a flour sample with respect to bran contamination, because the residue remaining after ashing procedure represents the mineral content of the sample. The ash test can also ensure product quality where it can minimize the reaction of enzyme. Meanwhile, protein contain is also important characteristic for marketing and purchasing wheat. The harder the wheat, the higher the protein content and the stable the consistency. Meanwhile, moisture content over 14% can affects the storage quality of flour and wheat. At higher moisture contents, mold growth, increases in microbial content, and infestation by insects are favored. Moreover, there are many types of flour that exist in food industries. For example, rice flour is fine flour made from ground rice. It is completely gluten free. Rice flour can be used as a thickener in sauces, as a breading for fried dishes and as the base for various baked goods. Besides, corn flour is starch derived from the corn grain. The starch is obtained from the

endosperm of the corn kernel. Corn flour can be used to make pastries, cookies and crackers. While, semolina flour is the coarsely ground endosperm of durum wheat. Durum wheat is the hardest variety of the six classes of wheat and has the highest protein content of all wheat. Because of this, it is ideal for making high-quality pasta.

One of the flour that is very popular among food industry is wheat flour. Wheat flour is milled from the entire kernel of wheat. Therefore, items baked with whole wheat flour tend to be heavier and denser than those made from enriched flour. One of the unique characteristic of wheat flour is it has higher amount of gluten. Gluten is the wheat's natural protein, and it's what gives baked goods their structure. When dough is kneaded, these glutens develop and become firm. The higher amount of gluten in this flour also indicate high amount of protein. This experiment will determine the quality parameter over the flour with different chemical and physical analysis. OBJECTIVES 1. To determine the pH of the wheat flour 2. To determine the acidity of the wheat flour 3. To determine the characteristic of different flour by using microscopic examination 4. To determine the flour infestation MATERIALS          

Flour Wheat,rice,corn,tapioca Distillled water,iodine,alcohol Mixture of glycerine and water (50:50) Phenolphthalein indicator 0.05 M NaOH Beaker pH meter Burettes Conical flasks

PROCEDURE A. pH for Only Wheat Flour

1. 2. 3. 4.

10 g of flour was shaked and mixed with 100 mL of water The mixture was allowed to stand for at least 30 minutes The mixture was filtered The pH of the filtrate was determined by using pH meter

B. Acidity for Only Wheat Flour 1. 18 g of flour was shaked with 200 mL of water in a conical flask 2. The conical flask along with the mixture was placed in a water bath at 40 C for 1 hour with the loosely stopper 3. The mixture was titrated and 100 mL filtrate was added with phenolphthalein 4. 100mL of clear filtrate was titrated with 0.05 M sodium hydroxide solution 5. The changes of colour was observed and recorded 6. The acidity of wheat flour is calculated C. Microscopic Examination ( Wheat, Rice, Corn & Tapioca Flour ) 1. 2. 3. 4. 5. 6. 7.

A minute quantity was placed on the slide A drop of alcohol was added A few drops of glycerine and water mixture (50:50) was added The samples was covered with a cover slip Excess liquid was removed with a filter paper The samples was examined under microscope The result of the starch diagram was observed and recorded

D. Flour infestation 1. 50 g of flour was weighed onto a flat surfaces 2. The flour was flattened by using a ruler 3. The flour was examined after two minutes for evidences of pimpling for examples surface disturbance 4. The result was observed and recorded

RESULTS A. pH for Wheat Flour Flour


Averag e

Whea 5.93 t flour 5.92 5.93


B. Acidity for Wheat Flour Initial 50 mL

Final 48 mL

Titre 2 mL

Calculation : 1 mL 0.05 M NaOH




Titre x 0.0068 x 100 Weight of sample


2 g x 0.0068 x 100 100 g 0.0136 #


0.0068 g KH2PO4

C. Microscopic Examination (Wheat, Rice, Corn and Tapioca Flour)


Rice Flour


Corn Flour

D. Flour Infestation Samples Cap Lily Cap Sauh

Infestation X

Diagram 1 : The infestation can be seen in Cap Lily flour. DISCUSSIONS From the experiments we need to determine the pH, acidity, infestation and microscopic examination of different types of flour which are wheat, rice, corn and tapioca flour. This need to be done in order to test the quality parameter of flour. For determination of pH that is conducted over wheat flour, the pH meter that is used to check the pH is calibrated first by using buffer 4 and 7 in order to make sure the results is not interrupted by last sample. The result shows that the pH of wheat flour is 5.93. Usually the pH of flour will falls within the range of 6.0 – 6.8. This is happens because of chlorine is applied to the flour. Thus, it is important to test the pH of the flour in order to know how much chlorine has been applied to the production of flour. The more chlorine was applied, the lower the pH. Unchlorinated flour has a pH of 5.8–6.5, whereas highly chlorinated flour can have a pH as low as 4.0. On the other hand, acidity of flour was tested by using titration method by using sodium hydroxide solution and filtrate solution of flour mixture that has been store for approximately 1 hour in water bath to measure the degree of acidity. It needs to be store in water bath in order to increases acidity of the flour since the changes in storage can also increase the amount of fatty acid. Besides, the end point of the titration is indicates by observing the changes of colour from yellow to pink by addition of phenolphthalein as indicator. The amount of potassium dihydrogen phosphate is then calculated by using this formula:1 mL 0.05 M NaOH KH2PO4



0.0068 g KH2PO4

Titre x 0.0068 x 100 Weight of sample

Hence, the result is 0.0136. As the acidity of the flour is also important to be test as it is indicator for freshness of the flour. Through flour infestation, we used two types of flour which are Cap Lily and Cap Sauh wheat flour. Cap Lily wheat flour show that it is infested where some crack can be seen after two minutes examined. This is happen because of the flour is not stored properly or it has been produce for a long period of time than other flour that is not infested yet. As it is not store properly, the moisture content of the flour may disrupted as higher amount than 14 % moisture of flour can also contribute to infest by insect. Meanwhile, Cap Sauh

wheat flour didn’t show any infestation as there are no any sign of hairline crack is present.

Through the experiment, there are some sources of error that we did that may affect the accuracy of the results during conducting the experiment. For example, the eyes is not parallel to the scale while read the burrete and the pH meter may be not calibrated properly as the past sample may interfere the reading of new samples. To minimize these errors various precautions should be taken such as, three consecutive of pH reading were carried out to eliminate the errors of the handlers. Besides, make sure all the instrument is calibrated properly and use the right techniques to determine the analysis. CONCLUSION In conclusion, the pH of wheat flour was 5.93 while acidity of wheat flour was 0.0136. From microscopic examination it was found that the shape of wheat flour is globular and round shape. The granular starch overlapped with each other and coagulates. Besides, rice flour show round and small shape of granules than wheat, corn and tapioca flour. They coagulate and overlapped with each other. On the other hand, corn flour results in globular shape and the size is small. Most of them is scattered and some coagulate with each other. Meanwhile, tapioca flour has globular shape and larger than rice, wheat and corn flour. They are coagulate with each other but not overlapped. Last but not least, flour infestation show that Cap Lily wheat flour is infested because the present of hair line crack is observed. While, Cap Sauh wheat flour did not have any infestation.

Study Questions 1. What are the major functional ingredients in flour which gives strength and structure to baked products? A major functional ingredient in flour which gives strength and structure to baked product is gluten. Gluten is a protein composite found in foods processed from wheat and related grain species. Gluten gives elasticity to dough, helping it rise and keeps its shape and often gives the final product a chewy texture. Gluten is the composite of a gliadin and a glutenin, which is conjoined with starch in the endosperm of various grass-related grains. Gluten is also insoluble in water. Wheat flour has high amount of gluten than other flour. 2. Why does incoming flour should have a moisture content of not more than 14%? Incoming flour should have moisture content of not more than 14 % because moisture content over 14% affects the storage quality of flour and wheat. At higher moisture contents, mold growth, increases in microbial content, and infestation by insects are favored. High moisture can also lead to production problems because flour agglomerates more readily as it becomes wetter. This often causes hoppers and other devices with bottlenecks to “bridge” when flour clumps, resulting in blocked passageways. 3. What is starch gelatinization? What happens to the starch granules at very high temperatures? Starch gelatinization is a process that breaks down the intermolecular bonds of starch molecules in the presence of water and heat, allowing the hydrogen bonding sites to engage more water. In addition, starch gelatinization means

an increase in the viscosity of the continuous phase of the dough or batter, and in this way the structure is stabilized. At very high temperature, starch granules that contain both linear amylose and branched amylopectin that heated by water become swollen and causes the amylose breakdown and some granules may collapse. This is due to water being absorbed away from the liquid phase into the starch granule. Starch begins to gelatinize between 60 and 70C.Hence, the process of gelatinize has occurred.

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