Effects of ingredients supplementation on textural characteristics and microstructure of yoghurt

The present investigation studied the effects of incorporating whey powder, whey protein concentrate and skim milk powder on textural characteristics and microstructure of yoghurt. Yoghurts were made using whole milk supplemented with 2% of whey powder, skim milk powder or whey protein concentrate. Yoghurt without any supplement was used as a control. Yoghurt supplemented with 2% whey protein concentrate was firmest while the control yoghurt was least firm. An average increase in viscosity of 1.2 to 5 times was observed on addition of whey powder, skim milk powder and whey protein concentrate. The control yoghurt showed the highest degree of wheying-off as compared to that containing whey protein concentrate; however, the syneresis values were similar for samples containing whey powder and skim milk powder. The microstructure analysis showed that yoghurts containing whey protein concentrate had a more regular and dense protein network as compared to those containing whey powder and skim milk powder. Yoghurts made with whey powder and skim milk powder had more voids and interstitial spaces as compared to those containing whey protein concentrate.