Rennet as a Cause of Bitterness Development in Quarg

Abstract

The effects of rennet level, culture composition and strain, and microbial contamination were evaluated as potential causes for bitterness in commercial quarg. Rennet level was the critical factor in the development of bitter flavor. When rennet was decreased from 3876 to 388 units/1000 kg of milk, bitterness was reduced and an acceptable product with an extended shelf life was obtained. The yield of laboratory produced quargs ranged from 28.42% for 3876 units/1000 kg rennet to 18.05% with no rennet addition. Rennet of 388 units/1000 kg resulted in laboratory and commercial yields of 21.90 and 22.50%, respectively. The microbiological results indicated low psychrotrophs, coliforms, and yeast and molds counts during the 6-wk storage trial, suggesting that bitterness was not the outcome of microbial contaminants. The nature of the starters tested (mixed cultures of Streptococcus lactis and Streptococcus cremoris with and without S. diacetilactis, or single strains of S. cremoris 134 and 584) did not play an important role in bitterness development during storage. © 1988, American Dairy Science Association. All rights reserved.