Beer, chillproofing

Chillproofers are added to freshly brewed beers to prevent the formation of haze upon cold storage. Papain-based enzymes have been used as chillproofers and their addition have to be monitored carefully, as overdosage results in flat beer. According to Skerritt et al (146), enzymatic methods currently used lack sensitivity or are slow and tedious. They have developed a polyclonal antibody-based kit for determination of these chillproofers. 

Some examples of in vitro hydrolytic modifications of proteins are shown in Table IV. The preparation of cheeses, chillproofing of beer, and the production of protein hydrolysates represent major uses of proteases. With the possible exception of cheese preparation, the application involves a substantial degree of hydrolysis. Therefore rather nonspecific proteases often are used. 

Chillproofing of Beer. In chillproofing of beer, proteolytic enzymes, primarily papain, are used to hydrolyze the proteins in beer contributed by the grain, malt, and yeast. The process must be controlled so that the polypeptides produced are no longer able to form an insoluble precipitate... 

Preparation of cheeses and soy derivatives Solubilization of protein concentrates Production of protein hydrolysates Gluten modification in bread doughs Chillproofing of beer Plastein formation Tenderization of meats Quality determination of proteins... 

Such applications appear to be more attractive for the use of bioreactors than traditional uses of endopeptidases for chillproofing beer, juice clarification, and curd formation in cheesemaking which currently use well established soluble enzyme processes. In the case of curd formation, hydrolysis of micellar k-casein by immobilized chymosin is questionable (56). 

Bromelain The purified proteolytic substance derived from the pineapples Ananas comosus and Ananas bracteatus L. (Fam. Bromeliaceae). Produced as a white to light tan, amorphous powder soluble in water (the solution is usually colorless to light yellow and somewhat opalescent), but practically insoluble in alcohol, in chloroform, and in ether. Major active principle bromelain. Typical applications used in the chillproofing of beer, in the tenderizing of meat, in the preparation of precooked cereals, in the production of protein hydrolysates, and in baking. 

Ficin The purified proteolytic substance derived from the latex of Ficus sp., which include a variety of tropical fig trees. White to off-white powders completely soluble in water. (Liquid fig latex concentrates are light brown to dark brown.) Major active principle ficin. Typical applications chillproofing of beer tenderizing of meat conditioner of dough in baking. 

The dyed proteins, though also not very cheap, are much more suitable from an economical point of view. The use of insoluble dyed proteins (e.g. hide powder azure) is very simple and handy. After the chosen reaction time the insoluble protein is removed by filtration or centrifugation and the absorbance of the filtrate is immediately measured. For instance, Rinderknecht proved that it was possible to determine trypsin activity with HPA (hide powder azure) in ng quantities per ml and proteolytic activities in biological materials, tissue extracts, serum, urine, faeces, etc. Other authors applied this substrate for assaying proteolytic activity in beer stabilized with chillproofing preparations containing proteases (mainly papain)... 

Other enzymes are required to obtain good quality beer with good shelf-life. The major use of non-malt enzymes is an enzyme that is added to fermented beer to chillproof the beer. Beer is fermented and aged under chilled conditions. Almost all packed beer is filtered while cold to achieve clarity. In spite of the filtration steps beer becomes cloudy after it is packed, distributed and chilled again for serving. The cloudiness that develops is caused by formation of haze particles called chill haze which are the result of the interaction between peptides and polyphenol compounds. 

Beer is extremely sensitive to oxygen and oxidative staring. With the development of enzymatic chillproofing it in now possible to pack beer and ship it over long distances while maintaining its appearance. 

An adsorbent application of major commercial importance is the adsorption of potentially haze-forming proteins from beer. This process is called chillproofing because the haze forms when the beer is cooled after a period of aging subsequent to bottling. Silica hydrogels and intermediate-density xerogels are employed, because both have pores of sufficient size (>10-nm average diameter) to admit the proteins in question. 

Of the many functions of proteolytic enzymes listed in Table I, the most extensively used commercially are chillproofing of beer, production of cheese, tenderization of meats, and production of protein hydrolysates. Two of the most active research areas at the moment include use of proteolytic enzymes for plastein formation (see Proteolytic-Induced Aggregation of Proteins, p. 99) and the solubilization of fish protein concentrate. 

Silproof. [SCM] Fine particle silica gel for chillproofing beer. 

Pepsin derived from the mucosa of hogs has found use in chillproofing beer and as a digestive aid. Microbial proteases (and papain) can replace pepsin in chillproofing, but there are no commercially available microbial proteases which show the low pH optimum (1.8-2.2) exhibited by pepsin. 

Products and Uses Utilized in beer, bread, cereals (precooked), meat (raw cuts), poultry, and wine. For chillproofing of beer, milk-clotting enzyme, meat tenderizing, cereals (preparation of precooked), and tissue softening agent. Derived from pineapple juice. 

Food Cheese manufacture Flour modification Stabilization of emulsions Extraction of fish and vegetable oils Tenderizing of meat Chillproofing of beer... 

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