Abstract:

A high-concentration reconstituted milk with containing 7.8% protein was fermented by Lactobacillus casei to
produce fermented milk for use in foods. We examined the changes in fermentation characteristics including acidicty, the
viable cell number of the starter and amino nitrogen content. A complex enzymatic preparation of lipase and protease and
the inoculum were added together to simultaneously hdyrolyze and ferment the reconstituted milk. As a result, a fermented
milk higher in acidity and amino nitrogen was yield. Both indicators were greatly influenced by the addition of the complex
enzymatic preparation. The fermented milk obtaiend after 72 h of single fermentation exhibited a titrtable acidity of 268.5 °T
and an amino nitrogen content of 0.117 g/100 g, compared to 414.4 °T and 0.132 g/100 g for that obtained after 72 h of
simultaneous hydrlysis and fermentation. Furthermore, titratable acidity and amino nitrogen content of fermented milk
increased with increasing amount of the enzymatic preparation added to the reconstituted milk. However, neither pH nor the
viable cell number of Lactobacillus casei was affected by the dosage of the enzymatic preparation.

Key words: high-concentration fermented milk, Lactobacillus casei, complex enzymatic preparation