How may overacid and bitter flavor defects in Quarg be avoided

High acid (low pH) in Quarg is due to the use of high starter inoculation, high incubation temperature (hence rapid acidification) [17], and inadequate cooling of the curd during storage - leading to increased microbial activity. Careful selection of starters is important to prevent bitterness [89]. Some strains of lactic acid bacteria used as starters in cheesemaking are known to produce bitter peptides. Psychrotrophic bacteria (e.g. Pseudomonas spp.) can grow in cheese [7], causing proteolysis and bitterness. Also, it has been suggested that increasing the calcium content of Quarg may result in bitterness.

Bitterness in Quarg is due to excessive residual rennet (chymosin) activity in the curd during storage [28]. A small amount of chymosin (0.5-1.0ml single strength per 1001) is used for manufacture of Quarg. High residual rennet activity at low pH results in excessive proteolysis, sometimes leading to the formation of bitter peptides. Therefore, excessive rennet use must be avoided and good whey drainage helps to reduce residual rennet levels in cheese.

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