IS ENZYMES USED IN FRUIT JUICE

Uses of Enzymes in Fruit Juice Wine Brwing Diltilling Industries
One of the major problems in the preparation of fruit juices and wine is cloudiness due primarily to the presence of pectins. These consist primarily of a-1, 4-anhydrogalacturonic acid polymers, with varying degrees of methyl esterification. They are associated with other plant polymers and, after homogenization, with the cell debris. The cloudiness that they cause is difficult to remove except by enzymic hydrolysis. Such treatment also has the additional benefits of reducing the solution viscosity, increasing the volume of juice produce (e.g. the yield of juice from white grapes can be raised by 15%), subtle but generally beneficial changes in the flavour and, in the case of wine-making, shorter fermentation times. The enzymes used in brewing are needed for saccharification of starch (bacterial and fungal a-amylases), breakdown of barley a-1.4- and a-1,3-linked glucan (b-glucanase) and hydrolysis of protein (neutral protease) t increase the (later) fermentation rate, particularly in the production of high-gravity beer, where extra protein is added. Cellulases are also occasionally used, particularly where wheat is used as adjunct to help break down the barley is b-glucans

.Due to the extreme heat stability of the B. amyloliquefaciens a-amylase where this is used, the wort must be boiled for a much longer period (e.g. 30 minutes) to inactivate it prior to fermentation. Papain is used in the later post-fermentation stages of beer-making to prevent the occurrence of protein-and tannin- containing ‘chill-haze’ otherwise formed on cooling the beer.Recently, ‘light’ beers, of lower calorific content, have become more popular. These require a higher degree of saccharification at lower starch concentrations to reduce the alcohol and total solid content of the beer. This may be achieved by the use of glucoamylase and/or fungal a-amylase during the fermentation.

A new enzyme preparation of fungal pectin lyase (EC 4.2.2.10) was shown to be useful for the production of cranberry juice and clarification of apple juice in the food industry (Semenova et al., 2006). A comparative study showed that the preparation of pectin lyase is competitive with commercial pectinase products. The molecular weight of homogeneous pectin lyase was 38 kDa. Properties of the homogenous enzyme were studies. This enzyme was most efficient in removing highly esterified pectin.
The zygomycete microfungus R. microsporus var. microsporus produced a 1,3-1,4-beta-D-glucan 4-glucanhydrolase (EC 3.21.73) which was able to hydrolyse beta-D-glucan that contains both the 1,3-and 1,4-bonds (barley beta-glucans) (Celestino et al., 2006). Its molecular mass was 33.7 kDa. Maximum activity was detected at pH values in the range of 4-5, and temperatures in the range of 50-60ºC. The enzyme was able to reduce both the viscosity of the brewermash and the filtration time, indicating its potential value for the brewing industry
Landbo et al, (2006) examined the clarification and haze-diminishing effects of alternative clarification strategies on black current juice including centrifugation and addition of acidic protease and pectinolytic enzyme preparation and gallic acid.