Properties of Labneh-Like Product Manufactured Using Enterococcus Starter Cultures as Novel Dairy Fermentation Bacteria

Abstract

The traditional yogurt starter, i.e. Staphylococcus thermophilus and Lactobacillus bulgaricus , has always been used to bring about the lactic acid fermentation during manufacture of concentrated yogurt known in Egypt as "Labneh". Different combinations of some strains of Enterococcus faecalis , isolated from Laban Rayeb (a type of fermented milk), in combination with a certain strain of Lactobacillus bulgaricus were used to produce a Labneh-like product. Chemical, microbiological and organoleptic properties of the Labneh-like product were assessed and compared to the characteristics of Labneh processed traditionally by two different dairy plants in Egypt. All treatments showed similar changes during storage at 5 ± 1°C for 28 d. Total solids, fat, titratable acidity and pH values coincided with those of Labneh. Some components increased until the seventh day, i.e. acetaldehyde and diacetyl, while other features, such as the ratio of soluble nitrogen/total nitrogen and tyrosine, increased until the fourteenth day of storage. Thereafter, no marked variations occurred. However, a decrease in tryptophan content of all products occurred during the storage period. Total viable count and count of lactic acid bacteria of Labneh-like product as well as Labneh increased until the end of the second week of storage and then decreased. Coliforms, yeasts and molds and psychrotrophic bacteria were detected in some fresh and stored samples. The starter culture which consisted of 1.5% Enterococcus faecalis 19 and 1.5% Enterococcus faecalis 22 was used successfully to manufacture a Labneh-like product with high acceptability when fresh or refrigerated at 5 ± 1°C.