Comparison of activities of bacteria and yeast starter cultures at different temperatures

Abstract

U ovom radu praćena je aktivnost različitih kvasaca i bakterija pri nižim temperaturama u cilju odabira najpogodnijih starter kultura za pekarstvo. Ispitana su tri soja kvasaca: Saccharomyces cerevisie TVG-4, Saccharomyces uvarum K-1 i ZP, te bakterije mliječne kiseline: Lactobacillus sanfranciscensis (L-3), Lactobacillus brevis (L-62) te Lactobacillus plantarum (L-73). Aktivnost starter kultura ispitana je pri temperaturama od 22°C, 12°C i 4°C. Pokusi su provedeni na sintetskim laboratorijskim podlogama te u smjesi brašna i vode kao realnom uzorku. Rezultati su pokazali da smanjenje temperature uzrokuje smanjenje fiziološke aktivnosti kvasaca i bakterija. Potrošnja šećera kao i sinteza produkata mikrobnog metabolizma je usporena. Kvasac Saccharomyces uvarum ZP pokazao je najbolju fiziološku aktivnost pri niskim temperaturama na sintetskim podlogama, međutim pokazao se nepogodnim za primjenu na realnim podlogama sastavljenim od brašna i vode. Bakterija Lactobacillus sanfranciscensis (L-3) pokazala je najbolju fiziološku aktivnost pri nižim temperaturama te najmanju osjetljivost na promjene temperature kako u sintetskim podlogama tako i u realnom uzorku.This study monitors the activity of different yeasts and bacteria at low temperatures with the purpose of selecting the most suitable starter cultures for bakery. Three types of yeast have been tested: Saccharomyces cerevisie TVG-4, Saccharomyces uvarum K-1 and ZP, and lactic acid bacteria: Lactobacillus sanfranciscensis (L-3), Lactobacillus brevis (L-62) and Lactobacillus plantarum (L-73). The activity of starter cultures has been tested at temperatures of 22°C, 12°C and 4°C. The experiments were conducted in synthetic laboratory media and in mixture flour and water as the actual sample. The results have shown that decreased temperatures cause a decrease in the physiological activity of both yeast and bacteria. The consumption of sugar, as well as the synthesis of the products of microbial metabolism is retarded. The Saccharomyces uvarum ZP yeast has shown the best physiological activity at low temperatures in synthetic media, but it has proven unsuitable for use in actual media composed of flour and water. The Lactobacillus sanfranciscensis (L-3) has shown the best physiological activity at low temperatures and the lowest sensitivity to temperature alterations both in synthetic media and in the actual sample