A method for manufacturing superior set yogurt under reduced oxygen conditions

Acid production and variation of dissolved oxygen (DO) concentration kinetics of LB81. Incubation at 43°C. (•) DO concentration and (■) acidity.

Influence of dissolved oxygen (DO) concentration on the acid production by yogurt culture LB81 incubated at 43°C. Acid production was measured through changes in titratable acidity (A) or pH (B). Incubation of LB81 under DO concentration fixed at 4 (•), 2 (▴), 1 (×), and 0mg/kg (■) and under normal air conditions (○).

Influence of dissolved oxygen (DO) concentration on the acid production by the single yogurt cultures Streptococcus thermophilus 1131 and Lactobacillus delbrueckii ssp. bulgaricus 2038 incubated at 43°C. Acid production was measured through changes in titratable acidity. Each of the cultures was incubated under a DO concentration fixed at 6 or 0mg/kg. Symbols: (♦) Streptococcus thermophilus 1131 control, (•) 6mg/kg, and (▴) 0mg/kg. Lactobacillus bulgaricus 2038 (◊) control, (○) 6mg/kg, and (□ 0mg/kg.

Effect of reduced dissolved oxygen (DO) fermentation (ROF) on acid production by the yogurt culture LB81 when the DO concentration in the yogurt mix was regulated to approximately 0mg/kg beforehand. Incubation was at 43°C. Symbols: (○) ROF at 43°C and (■) the control fermentation at 43°C.

Preservation of acid productive activity of the bulk starter made by reduced dissolved oxygen fermentation (ROF). Incubation was at 43°C. Symbols: (•) LB81 starter maintained at 5°C for 3 d with the control fermentation; (▴) LB81 starter maintained at 5°C for 7 d with the control fermentation; (▵) LB81 starter maintained at 5°C for 7 d with the ROF.

Effect of low-temperature reduced dissolved oxygen (DO) fermentation (LT-ROF) on acid production by the yogurt culture LB81 when the DO concentration in the yogurt mix was regulated to approximately 0mg/kg beforehand. Incubation was at 37°C. Symbols: (•) LT-ROF and (▴) control fermentation at 37°C.

Appearance of the yogurt made by low-temperature reduced dissolved oxygen (DO) fermentation (LT-ROF) and the control fermentation at 37°C, when scooped up with a spoon.