食品加工与技术杂志

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High Protein Powders Fortification of Nonfat Yoghurt: Impact of Protein Source, Protein to Total Solids Ratio, Storage, and Seasonality on the Functionality of Nonfat Yoghurt Made Using Glucono-δ-Lactone (GDL)

Kartik Shah, Prafulla Salunke, Lloyd Metzger

Nonfat yoghurt is a popular fermented product across the world. High protein powders such as Skim Milk Powder (SMP), Nonfat Dry Milk (NDM), and Milk Protein Concentrate (MPC) can be utilized in yoghurt formulations. The final Total Solids (TS), source and amount of protein in the formulation, and the physicochemical changes during storage may impact the functionality of yoghurt-type products. The objective of the study was to evaluate the effects of storage of SMP, NDM, MPC40, and MPC70 on the functionality of nonfat yoghurts at three different protein/ TS levels. Additionally, the impact of SMP and NDM manufactured in different seasons (summer and winter) on yoghurt functionality was also studied. Three different lots of each powder were collected and divided into 3 portions and were stored for 3, 9, and 15 months. At each storage time, yoghurt with %protein/%TS of 4/12.5, 4.5/13.5, and 5/15.5 were produced from each lot. A Rapid Visco Analyzer (RVA) method was utilized to produce yoghurt using glucono-δ-lactone (GDL). Storage time did not have a significant effect (p>0.05) on the functional properties of yoghurts fortified with NDM, MPC40, and MPC70 at all protein/TS ratios. In conclusion, the storage of milk powders has a minimal influence on the functional properties of nonfat yoghurt, whereas the use of MPC had a substantial impact on the functionality of nonfat yoghurt.