Bleaching Efficacy of Ozone Gas in Liquid Whey and its Effects on Flavor of 80% Whey Protein Concentrate and Norbixin Partitioning in Full Fat and Fat Free Cheddar Cheese.

SMITH, TUCKER J. Bleaching Efficacy of Ozone Gas in Liquid Whey and its Effects on Flavor of 80% Whey Protein Concentrate and Norbixin Partitioning in Full Fat and Fat Free Cheddar Cheese (Under the direction of Dr. MaryAnne Drake). As demand for whey ingredients increases, it is important to study alternative cheese and whey treatments which decrease the need for harsh chemical bleaching agents during the liquid whey production process. Currently, the two approved bleaching agents in the US are hydrogen peroxide and benzoyl peroxide. Bleaching with these agents causes off flavors in products containing whey protein ingredients. Studying the difference in annatto partitioning during full fat and fat free cheese makes, along with the use of a novel bleaching agent, ozone, assists in the search for a method of producing the highest quality whey protein ingredients with both optimal flavor and color characteristics. The objective of the first study was to determine the viability of ozone as an alternative bleaching agent for fluid whey. Flavor effects and bleaching efficacy of ozone gas on liquid whey and whey retentate were evaluated in bench top experiments prior to pilot scale manufacture of 80% whey protein concentrate. Bleaching of retentate with ozone was higher at 35°C compared to 50°C (p<0.05); temperature did not affect liquid whey bleaching with ozone (p > 0.05). In bench top studies, a 63 % decrease in norbixin content was observed in fluid whey after 45 min ozone exposure. In pilot scale manufacture, WPC80 from HP bleached whey had 27% norbixin destruction while that bleached with ozone had a 15% reduction. Ozone-treated WPC80 exhibited animal and flour/pasta flavors and HP bleached WPC80 was characterized by cabbage and fatty flavors not present in unbleached WPC80. Higher levels (p<0.05) of nonanal and decanal were present in the ozone WPC80 while higher levels (p<0.05) of pentanal, DMDS, hexanal, heptanal, 2-pentylfuran, and octanal were present in the HP WPC80 compared to the control. These results suggest that ozone bleaching does not represent a promising alternative to approved bleaching agents in whey protein production although it could possibly remain feasible at or close to saturation levels. The objective of the second study was to better understand norbixin characteristics in whey by evaluating the norbixin partitioning differences in cheese and whey in full fat and fat free Cheddar cheese manufacture. Full fat and fat free cheeses along with corresponding wheys were produced in quadruplicate. Norbixin extractions were performed on the colored milk, the unseparated/unpasteurized whey, and the pressed Cheddar cheese. An average of 10% of the norbixin added to the full fat cheese milk was recovered in the whey and 82% was recovered in the cheese. Similarly, 12% of the norbixin added to skim milk was recovered in the skim milk cheese whey and 76% was recovered in the fat free cheeses. Level of norbixin addition to cheese milk and milk fat content had no impact on norbixin recovery in cheese or whey (p>0.05). These results suggest that fat content has little impact on norbixin binding or entrapment during the cheese make process. Bleaching Efficacy of Ozone Gas in Liquid Whey and its Effects on Flavor of 80% Whey Protein Concentrate and Norbixin Partitioning in Full Fat and Fat Free Cheddar Cheese by Tucker James Smith A thesis submitted to the Graduate Faculty of North Carolina State University in partial fulfillment of the requirements for the degree of Master of Science