Incorporation of whey protein isolate (WPI) into paneer : impact on yield, texture and microstructure : a thesis submitted in partial fulfilment of the requirements for the degree of Master of Food Technology, Massey University, Palmerston North, New Zealand

Abstract

Paneer is a traditional Indian dairy product rich in protein, fat, calcium, phosphorous, and vitamins though relatively low in whey protein content due to the conventional heat and acid coagulation processes, highlighting the innovative approach for increasing the nutritional content in paneer. This study investigates the incorporation of Whey Protein Isolate (WPI) into paneer to increase the protein content and nutritional value, while evaluating the effects on yield, texture and microstructure of the paneer. Different formulation methods were tried, including the addition of WPI with and without oil incorporation, also by varying the sequence of mixing with skim milk. A 3% WPI concentration was selected based on preliminary study, as increase in concentration led to premature gelation of whey protein while heating and due to processing difficulties. The effect of WPI addition on the yield of the paneer and whey protein retention was studied. A significant improvement in yield of paneer was observed for WPI fortified samples with an increase of 12 to 26% compared to the control. A significant increase in weight from 100 grams to 350 grams was also observed in the paneer samples while fortified with WPI. SDS-Page was used to confirm the incorporation of whey protein into the paneer system. To understand the structure and other functional changes occurred during WPI incorporation, particle size distribution analysis was conducted before and after the heat treatment to the milk. Confocal laser scanning microscopy (CLSM) was employed to understand the protein network and to confirm the incorporation of oil into the system. Texture profile analysis (TPA) helped in further understanding the hardness, cohesiveness, springiness and chewiness of the fortified sample and compare it with the control. TPA was also used for the pressing of the curd into paneer and the rheological behavior during the pressing was studied. Modelling of the TPA data demonstrated that the curd compression profile was primarily influenced by the total curd mass rather than the formulation method of the paneer. Overall, the study proves that WPI can be successfully incorporated in the paneer to improve its overall protein content and yield with notable effects on its microstructure and texture. The texture of the samples with oil emulsions (SOH-WP, WOH-SP, SWOH-P) showed an increase in hardness compared to the control and SWP showing that the texture of the paneer is highly dependent on method of whey addition. Further studies can be done on improving the texture, sensory properties and formulation of the paneer. The impact of different coagulating agents and detailed nutritional analysis, like in vitro digestibility studies could be studied to assess the nutritional quality and protein bioavailability.