Starter Culture Development for Spontaneously Fermented Buttermilk

Abstract

Fourteen fermented milks were made from ultra-high temperature (UHT) treated milk using mixtures of three strains of lactic acid bacteria (LAB) and two yeast strains isolated from spontaneously fermented buttermilk (SFB). The isolates used for this experiment were Lactococcus (Lc.) lactis ssp lactis strain NGLC1, Lc. lactis ssp lactis strain NGLC2, Lactobacillus plantarum strain NGLB1, Saccharomyces cerevisiae strain NGY1 and Kluyveromyces marxianus strain NGY2. Inoculated milk was fermented for 48 h at 30 ºC and samples for analysis were taken every 12 h. At each sampling time, viable cells and pH were measured. Carbohydrates, organic acids, and amino acids were analysed using high pressure liquid chromatography. Volatile compounds were analysed using headspace gas chromatography. Ten out of fourteen products showed adequate fermentation since they had a final pH between 4.01 and 4.09 and an average microbial count of log 9 cfu mL^-1 of LAB and log6 cfu mL^-1 of yeasts. Eight organic acids, 15 volatile compounds and 22 amino acids were detected in the fermented products. Out of the 15 volatile compounds four acetaldehyde, diacetyl, ethanol and acetoin were detected as major aroma compounds. Pure and mixed strains used to ferment 12 products were recommended as starter cultures for SFB as they showed fast acid production, metabolize citrate and produce acceptable levels of organic volatile compounds.

Keywords: Starter culture, lactic acid bacteria, yeasts, organic and volatile compounds

Cite this Article

Negussie Gebreselassie, Pal Akrust, Fekadu Beyene. Starter Culture Development for Spontaneously Fermented Buttermilk. Research & Reviews: A Journal of Biotechnology. 2016; 6(1): 11–25p.