Ethanol Production by Fermentation

Et hanolPr oduct i on ByFer ment at i on Fermentation Ferme ment at i on i st heanaer obi cbr eakdown ofsugar si n hi ghcar bohydrat e f oods( f r ui t sandg r ai ns )i nt oal c oholbyt heac t i onofy e as t s .Y eas t sar euni c e l l ul ar f ungiwhi ch cont ai n avari et yofenzyme mesres ponsi bl ef orcarryi ngoutmet abol i c r eact i ons.I nt hepr oduct i on ofal cohol i cdri nks,yeastact son gl ucoseorsucr ose i nt heabsenceofai rt opr oduceCO2  andet hanol . St e psI nv o l v e di nt heFe r me nt at i o no fSuc r o se

1)Yeastsec r et est heenzyme mesi nve r t asewhi chcat al yses t hehydr ol ysi sofsucr oset ogl ucoseandf ruct ose. invertase

C12H22O11(aq)+H2O(l)

→

C6H12O6(aq)+C6H12O6(aq)

2)Thes e si mpl e sugar s ar e anaer obi cal l y conv er t ed t o car bon di oxi deandet hanolbyz yma mase,whi chi sal so pr oducedbyt hey east . C6H12O6(aq)

 zymase →

2C2H5OH(aq)  +2CO2(g)

1.Fer ment at i on occur si n af er ment at i on vat .Thevat sar est er i l i sed t oensur e t hatt her earenoundesi r abl eyeast /f ungi /bact er i apr esentwhi chcoul daffect

B. t hequal i t yoft hepr oduc t .N.   bac t e r i ao xi di s e se t hano lt oe t hano i cac i d.The t ypeofyeastuseddet er mi nest heflavourand col oursoi fundesi r abl eyeast s ar epr esent ,t hequal i t yandconsi st encyoft hepr oductwi l lbeaffect ed.

2.Thesubst r at ef ort hef er ment at i on i susual l yt r eat edwi t hSO2  whi chact sasa s t e r i l i s i ngage nt . 3.Thef er ment at i onvesse l sareseal edt opr eventai r( whi chwoul doxi di seet hanol t oe t hanoi c aci d) and bact er i a/f ungi( whi c h woul d cause unwa want ed si de r e ac t i o ns )f r o me nt e r i ng .

4.Thet emper at ur eand pH depe nd on t he spec i esofy eas tused and i n mos t cases,t hevessel sneedt obecool edsi ncei ti sanexot hermi cpr ocess. 5.Tool ow at emper at ur ewi l lcauset heenz ymest owor kt oosl owl yandi ncr eases t hepossi bi l i t yofunwant edbact eri alf erment at i on.Toohi ghat emper at ur ewi l l al t er t he cel ls t r uct ur e oft he yeastand pr ot ei ns wi l lhave t he i ncorr ect st ruct ur et o cat al yse t her eact i on.Athi ghert emper at ur es,t he pr ot ei nswi l l  becomedenat ur ed. 6.Ther ear eot hersubst ancesaddedt ot hef er ment at i on mi xt ur e,e. g.vi t ami ns, mi ner al s,ext r a sugar( f orsweet ness) ,aci ds( t oenhanceflavour ) ,enzymes( t o ac hi e v econs i s t e ntqual i t y–papai nf orc l ar i t y) . 7.Thel engt h oft i mef orf er ment at i on var i esdependi ngon t hepr oduct–l onger t i mesyi el ddri erwi nesandshort ert i mesyi el dsweet erwi nes.

Distillation  Ther ei sal i mi tt ot he amount of al cohol t hat can be pr oduced by f er ment at i on.Thi si sbecausewhen t heal coholcont entr i sesabove15%,i twi l l ki l lt heyeast .Thedensi t yatapart i cul art emper at ur ecan beusedt odet er mi ne t heper cent ageofet hanol .Duri ngf erment at i on,t heal coholcont enti smoni t ored  by me asur i ng t he speci fic gr avi t y( a measur e ofdensi t y) .I fa hi gheral cohol i c c ont e nti sde s i r e d,t he r ear e2o pt i o ns : r ee t hanol–t hi spr oducesa f or t i fied bev er age,e. g.sher r yi sa  Add mo f o r t i fie dwi ne ;



Di st i l l at i on –t hi spr oducesa spi ri twhi ch i st ypi cal l y3040% et hanol ,

B.ci e. g.r um,whi skey ,vodka,br andy .N. der ,bee rand wi ne ar e not di s t i l l ed. I ncr easi ngt heal coholcont entt o above15% al so i ncr easest heshel fl i f eoft he pr oduct .

Uses of Ethanol 

I ti sacommonl yusedsol venti nt heper f umei ndust rybecausei tcan di ssol ve

 bot hpol arandnonpol arsubs t ances,e. g.nai lpol i shesandper f ume s; ti sus e dasanant i s e pt i c ,e . g .i nme di c alwi pe sandant i bac t e r i alhandg e l s ;  I i nuseofe t hanoli sasaf uelorf ueladdi t i v ef orv ehi cl esbecausei ti sa  Thema cl eansour ceofener gy.