61B-4 |
Odor-active compounds of liquid whey |
Y. KARAGUL-YUCEER, Dept. Food Science, North Carolina State University, Raleigh, NC 27695, K. R. Cadwallader, Dept. Food Science, University of Illinois, Champaign-Urbana, Champaign, IL, and M. A. Drake. Whey is the liquid by-product of cheese production. Fluid whey has more than 93 percent water but includes approximately half of the original nutrients of milk. The United States is the largest producer of whey products in the world. Flavor consistency is an issue for whey products since a bland, flavorless product is expected. These flavor inconsistencies may initiate in the raw whey prior to further processing. The objective of this study was to determine the differences in flavor volatiles of fresh liquid Cheddar whey as impacted by starter culture rotation. Three fresh composite whey samples (I, II, III) (4 Liters each) were obtained from the same commercial Cheddar cheese plant. Each sample (400 ml) with internal standards (2-methyl-3-heptanone and 2-methyl-pentanoic acid) was extracted with diethyl ether in duplicate, followed by isolation of volatile material by high vacuum distillation. Volatile extracts were separated into neutral/basic and acidic fractions and analyzed by gas chromatography-olfactometry (GCO). The potent odorants were evaluated by aroma extract dilution analysis (AEDA). Headspace volatiles were isolated by solid phase microextraction (SPME)-GCO. Splitless injection was employed for GCO. Compounds were identified by comparison of retention indices, odor properties and GC-MS data against reference standards. Diacetyl (buttery), hexanal (green), 2-acetyl-1-pyrroline (popcorn), methional (potato), (E,E)-2,4-decadienal (frier oil) (E,Z)-2,6-nonadienal (cucumber) and (E,E)-2,4-nonadienal (fatty) were potent neutral/basic aroma-active compounds identified in all three samples. The odor intensities of hexanal, 2-acetyl-1-pyrroline and (E,E)-2,4-decadienal were higher in sample II than others. Sample III had the highest intensities of diacetyl and methional. Free fatty acids were predominant volatiles in the acidic fractions and intensities differed among the whey samples. Liquid whey flavor volatiles are impacted by starter culture rotation. These findings will aid in identification of methods to minimize flavor variability in dried whey products.
Session 61B, Food Chemistry: Flavor and aroma chemistry
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