Master of Science / Food Science Institute / Jayendra Amamcharla / Greek yogurt is one of the largest-growing sectors in the dairy industry accounting for over 25% of yogurt sales in the United States. Greek yogurt is produced by removing a portion of water and water soluble components from yogurt. Consequently, a large quantity of Greek yogurt whey (GYW) is being produced as a co-product. GYW is compositionally different from cheese whey, and thus poses economic and environmental challenges to the dairy industry. The objective of the present study was to evaluate two physical treatments as alternative methods for separating valuable GYW components: magnetic fluid treatment (MFT) and the addition of sepiolite, a clay mineral. A MFT chamber was designed using four pairs of neodymium magnets arranged to produce a magnetic field strength of 0.6 Tesla. Three batches of GYW each from two manufacturers were procured. A 2×3 factorial design was used with MFT or without MFT and the addition of zero, two, or four grams of sepiolite per 100g of GYW. The pH of GYW was adjusted to 7.2 using 5N NaOH solution, and the GYW was pumped at a rate of 7.5 L/min through the MFT system with or without MFT chamber attached. The sample was split into three sub-samples, heated to 80°C, and sepiolite was added as per the experimental design. The samples were centrifuged at 1,000g for five minutes. The top aqueous layer was separated and analyzed for total solids, ash, lactose, protein, calcium, phosphates, and sodium content along with color. MFT did not influence the analyzed whey components (P > 0.05) except for lactose. However, addition of sepiolite influenced protein content and a* and b* color values for the top aqueous layers (P < 0.05). Both levels of sepiolite addition resulted in about a 50% decrease in protein compared to original GYW. Adding two grams of Sepiolite per 100g of GYW from manufacturer 1 resulted in b* decreasing from 25.99 to 8.16 compared to treated GYW with no sepiolite. Sepiolite was found to have possible applications in the removal of proteins and color pigments in GYW.

The growth of the Greek-style yogurt market is causing many problems for dairy companies who are trying to handle the voluminous whey by-product. Acid whey, unlike sweet whey, has a low amount of protein and high amounts of lactic acid, calcium, and other minerals. Therefore, it has limited commercial value to the food industry and often requires additional processing for disposal. Lactic acid and calcium solutions have shown efficacy in increasing the tenderness of beef and other types of meat. The purpose of this project is to investigate the use of acid whey, with its high amounts of lactic acid and calcium, to tenderize beef (eye of round, IMP 171C) during marination. This study evaluated the effects of marination of utilizing acid whey in improving quality parameters of beef. 13 roasts (Top round steaks from USDA Select steers) were randomly assigned to one of six marination treatments: (1) calcium chloride, (2) lactic acid, (3) phosphate (4) acid whey (lot 1), (5) acid whey (lot 2), and (6) control. Steaks were marinated in vacuum pouches, aged for 48 hours, cooked to 70º C and evaluated by a consumer sensory panel and other quantitative tests (texture analyzer, colorimeter, collagen, cook loss, and pH). Marination with acid whey increased the tenderness and juiciness ratings without decreasing hedonic liking scores for the overall flavor or aftertaste of the beef samples.