71A-51 |
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Y. YOON and M. A. Drake. Dept. of Food Science, North Carolina State Univ., 331 Schaub Hall, Box 7624, Raleigh, NC 27695-7624 Skim milk powder (SMP) is widely used for direct consumption and as an ingredient in foods. Flavor and flavor stability of SMP is crucial. SMP has a long shelf life (12 to 36 mo), and little work has addressed flavor variability or stability in SMP. Our objectives were to characterize flavor variability of fresh SMP and flavor stability of SMP throughout 18 mo storage, using both sensory and instrumental analyses. Fresh low heat SMP (< 1 mo old) was received in duplicate 23 kg bags from eight production facilities on three different occasions. These SMP bags were subsequently stored at 21 or 35 °C and sampled after 0, 6, 9, 12, 15, or 18 mo storage. At each sampling, reconstituted SMP (10% w/w) were prepared and evaluated by sensory and instrumental analyses. Descriptive sensory analysis was conducted using a trained panel and a previously established sensory language. Volatile chemical compounds were analyzed by solid phase microextraction (SPME) with gas chromatography-ion trap mass spectrometry. Fresh SMP from different facilities were distinct by sensory and instrumental analyses (P < 0.05). Volatile compound differences in fresh SMP included dimethyl sulfide, diacetyl, and nonanal, while sensory differences were primarily characterized by differences in cooked and sweet aromatic flavor intensities. Sensory and instrumental differences were also observed for storage stability (P < 0.05). Volatile lipid oxidation and Maillard reaction compounds such as hexanal, nonanal, decanoic acid, and maltol increased with storage time at 21 or 35 °C, although qualitative and quantitative differences in these compounds were also observed with storage temperature. Cardboard, fatty/frier oil, and stale/grapey flavors increased with storage time concurrently with instrumental volatile changes. These results will aid in the identification of processing and/or storage regimes to optimize flavor quality of SMP.
Session 71A, Dairy Foods: General
2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana |