|Institution:||South Dakota State University|
|Full text PDF:||http://openprairie.sdstate.edu/etd/1041|
United States is one of the largest producer of cow’s milk in the world and a substantial portion of this milk is converted into dried milk products, a category that is becoming increasingly important to the dairy industry. The processing treatments on skim milk and skim milk concentrate affect the functionality of resultant powders made from them, therefore processing treatments are crucial to modify physical and functional properties of skim milk, skim milk concentrates and the powders made from them. The objective of this research was to explore impact of new processing technologies hydrodynamic cavitation (HC) and carbon dioxide (CO2) injection on physical and functional properties of skim milk and skim milk concentrate (SMC) respectively. In one of the experiment it was found that HC had little effect on casein micelle size and heat stability, however it produced acid gels with final gel strength (G’) almost similar to the gels from conventionally heated milk samples in the treatments that involved simultaneous heating along with cavitation. HC can therefore serve as an alternate technology to scale-free heat milk for yogurt manufacturing. HC without involving heating at higher flow rates had a positive effect on rennet coagulation time. In another experiment effect of CO2 injection technology to modify the pH of skim milk concentrate and decrease the apparent viscosity of high solids SMC was studied. This experiment was carried out first in lab and then scaled up at pilot plant to study the feasibility of this technique. In both the experiments significant difference (p ≤0.05) in apparent viscosity was observed between CO2 treated and control SMC samples. High solids (55-57% total solids) concentrate obtained from CO2 treated SMC sample had significantly (p ≤ 0.05) lower apparent viscosity compared to control. Also the powders produced from concentrate that was CO2 treated had higher bulk density, improved solubility, better heat stability on reconstitution in comparison to powders from control concentrate. Overall the observation from these experiments suggest that both HC and CO2 injection can serve as technologies that can help modify physical and functional properties of skim milk and concentrate for better. Advisors/Committee Members: Lloyd Metzger.