1Graduated from Dairy Science College, Karnataka Veterinary, Animal and Fisheries Sciences University, Bangalore, 560024, India
2Department of Dairy Technology, Dairy Science College, Karnataka Veterinary, Animal and Fisheries Sciences University, Bangalore, 560024, India
3Department of Dairy Microbiology, Dairy Science College, Karnataka Veterinary, Animal and Fisheries Sciences University, Bangalore, 560024, India
4Ph.D. Student in Poultry Nutrition, Department of Poultry Science, Veterinary College, Karnataka Veterinary, Animal and Fisheries Sciences University, Bangalore, 560024, India
Yoghurt is a unique fermented dairy product, consumed throughout the world and the trend of consumption is increasing due to its unique health benefits. Yoghurt mix is often supplemented with MSNF (milk solids-non-fat), it may contain as much as 5.7% unhydrolysed lactose. Lactose can be hydrolysed with an enzyme lactase. Deficiency of lactase in lactose-intolerant persons leads to gastrointestinal disorders; such consumers may find it difficult to consume lactose unhydrolysed yoghurt. The production of lactose hydrolysed yoghurt by pre-hydrolysing of lactose in the yoghurt mix by enzymatic hydrolysis of lactose was studied using standard materials and methods. Among the different levels of enzyme examined (0.12 to 0.56% of yoghurt mix with increment of 0.04% at each level), 0.16, 0.32 and 0.52% were found suitable to hydrolyse 50, 70 and 90% lactose in the yoghurt mix, respectively. Lactose hydrolysed yoghurt (LHY) prepared from 70% followed by 50% lactose hydrolysed mix (LHM) had significantly higher scores for body and texture, flavour and overall acceptability than control (P<0.05). However, 90% LHY secured significantly lower scores for sensory scores (P<0.05) and lactose hydrolysis in mix had no effect on colour and appearance of yoghurt at all levels of hydrolysis. Lactose hydrolysis reduced the setting time by 30-45 min over control (210 min) (P<0.05). The curd strength was checked by measuring penetration (mm/5sec) using a cone penetrometer. The yoghurt from 50, 70 and 90% LHM had shown significantly increased penetration of 280, 325 and 395 mm/5sec as compared to control (195 mm/5sec) and the amount of whey separation increased as the degree of lactose hydrolysis increased (P<0.05).