Conventional and alternative principles for stabilization of protein and polyphenol fractions in beer

Abstract

Beer haze is primarily formed through complexation of protein and polyphenolic beer ingredients. The problem of reducing susceptibility of beer haze formation can be done either by lowering protein and/or polyphenol levels, or by minimizing the molecular size of protein/polyphenols. In experimental part of this work the shelf life of unstabilized beer is being compared with beer stabilized with various standard products, such as PVPP and silica gel. Furthermore, the trials have been made to prove the functionality of a new product consisting of carrageenan and cross-linked PVPP. The method used to determine shelf life was haze forcing test (0/60?C). Extract, alcohol, bitterness, foam, haze, color and pH were also monitored. The test results showed expectedly that combined treatment of beer ensures the highest level of product stability. Through selective stripping of polyphenols and protein fractions it is possible to improve shelf life of beer to a significant extent.Mutnoca piva nastaje prvenstveno kao posledica nastajanja kompleksa izmedju proteinskih i polifenolnih sastojaka piva. Problem smanjenja sklonosti nastajanja mutnoce se moze resiti bilo smanjenjem sadrzaja proteina i/ili polifenola, bilo smanjenjem velicine molekula proteina/polifenola. U eksperimentalnom delu ovoga rada razmatrana je promena dugotrajnosti piva izmedju potpuno nestabilizovanog piva, piva stabilizovanog PVPP-om pri razlicitim kolicinama i nakon upotrebe PVPP-a u kombinaciji sa silika gelom. Rok trajanja odredjen je metodom forsir testa (0/60?C). Nadalje, ucinjeni su pokusaji da se potvrdi funkcionalnost jednog novog proizvoda koji se sastoji od karaginana i umrezenog PVPP. Ubrzani test (0/60?C) je primenjen kao metoda za odredjivanje trajnosti piva. Pored toga pracene su promene osnovnih parametara u pivu kao sto su ekstrakt, alkohol, gorcina, pena mutnoca, boja i pH vrednost. Kombinovani tretman je, kao sto je i ocekivano omogucio najvisi nivo stabilnosti produkta. Selektivnim odstranjivanjem dela polifenolnih i proteinskih frakcija, tj. uspostavljanjem ravnoteze ovih faktora, moguce je znacajno poboljsati trajnost piva.