Flavor and Flavor Chemistry of Liquid Mozzarella and Cheddar Cheese Whey
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Date
2009-09-08
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Abstract
Whey protein is widely used in numerous ingredient applications. Cheddar and Mozzarella cheeses are the primary sources for dried whey protein production. Differences in the flavor of fresh whey may influence the final whey protein flavor. Whey protein flavor is highly variable and off-flavors in dried whey products can carry through into ingredient applications and negatively affect consumer acceptance. The first objective of this study was to evaluate the impact of antioxidant addition in prevention of flavor deterioration of fluid whey and flavor of whey protein. The second objective of this study was to compare the flavor and flavor stability of fresh and stored liquid Cheddar and Mozzarella whey.
For the first objective, Cheddar or Mozzarella liquid whey were manufactured using standard cheese make-procedures. The wheys were then pasteurized and subjected to fat separation. Ascorbic acid, whey protein hydrolysate (WPH), or nitrogen flushing were then administered. Wheys with no antioxidant addition and without fat separation were included as controls. Wheys were stored at 3oC and evaluated by sensory and instrumental analyses after 0, 2, 4, 6, and 8 days. In a subsequent experiment, selected treatments were incorporated into liquid Cheddar whey and processed into whey protein concentrate (WPC). Whey and WPC flavors were documented by descriptive sensory analysis, and volatile components were evaluated by solid phase micro-extraction with gas chromatography mass spectrometry (SPME-GC-MS). Cardboard flavors increased in fluid wheys with storage. Liquid wheys with ascorbic acid, WPH or nitrogen flushing had lower cardboard flavor
across storage compared to control whey. Lipid oxidation products, hexanal, heptanal, octanal and nonanal increased in liquid whey during storage, but liquid whey with added ascorbic acid, WPH or nitrogen flushing had lower concentrations of these products compared to untreated controls. Mozzarella liquid whey had lower flavor intensities than Cheddar whey initially and after refrigerated storage. WPC with added ascorbic acid or WPH had lower cardboard flavor and lower concentrations of pentanal, heptanal, and nonanal compared to control WPC. WPC and liquid whey with added WPH, however, had a distinct potato flavor by sensory analysis which was absent in control products or products with added ascorbic acid.
In the second study, pasteurized, fat-separated Cheddar and Mozzarella wheys were manufactured in duplicate and evaluated immediately or stored for 3 days at 3oC. Sensory properties were documented by descriptive sensory analysis and volatile components were extracted and characterized by solid phase microextraction with gas chromatrography-mass spectrometry (SPME-GC-MS), direct solvent extract (DSE) with solvent assisted flavor evaporation (SAFE) with GC-MS and gas chromatography-olfactometry (GC-O) with aroma extract dilution analysis (AEDA). Cheddar and Mozzarella wheys were distinct by sensory and volatile analyses (p<0.05). Fresh Cheddar whey had higher intensities of buttery and sweet aromatic flavors and higher cardboard flavor intensities following storage compared to Mozzarella whey. Fifty aroma-active compounds were identified by GC-O. High aroma impact compounds (FDlog3 > 8) in fresh Cheddar whey included diacetyl, 1-octen-3-one, 2-phenethanol, butyric acid, and (E)-2-nonenal, while those in Mozzarella whey included diacetyl, octanal, (E)-2-nonenal, and 2-phenethanol. Concurrently, fresh Cheddar whey had increased concentrations of diacetyl, 2/3-methyl butanal, (E)-2-nonenal, 2-phenethanol, and
1-octen-3-one compared to fresh Mozzarella whey. Lipid oxidation products increased in both whey types during storage but increases were more pronounced in Cheddar whey than Mozzarella whey.
Collectively, these studies suggest that lipid oxidation is a primary source of flavor and flavor degradation in fluid whey. Similar aroma-active compounds at different concentrations comprise the flavor of Cheddar and Mozzarella whey and these influence observed differences in lipid oxidation and flavor during subsequent storage. Addition of an antioxidant to liquid whey prior to further processing may be beneficial to flavor of spray dried whey protein.
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GC-O, flavor chemistry, liquid whey, Cheddar, Mozzarella
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Degree
MS
Discipline
Food Science
