71A-16

A. COFFEE¹, M. E. Carunchia Whetstine², J. U. McGregor¹, and M. A. Drake². (1) Dept. of Food Science and Human Nutrition, Clemson Univ., 224 Poole Agricultural Ctr., Box 340371, Clemson, SC 29634-0371, (2) Dept. of Food Science, North Carolina State Univ., 408 Withers Hall, Box 7624, Raleigh, NC 27695-7624

The shelf life of whole milk powder (WMP) is approximately 6 to 9 mo at 21 °C, considerably shorter than that of skim milk powder. Extending shelf life of WMP would be desirable. Recent research has indicated that the application of rice bran oil (RBO) could enhance shelf life of WMP. Further research is necessary to characterize flavor and flavor stability of WMP with added RBO. Our objective was to conduct a shelf-life study to characterize the flavor of RBO-fortified WMP by sensory and instrumental analysis. An accelerated shelf-life study (40 days at 45 °C, a_w 0.31) was conducted to accelerate flavor changes in WMP. At time 0 and after 40 days, flavor of WMP was characterized by sensory and instrumental analysis. Descriptive sensory analysis (n=11) was used to document the sensory perception of flavor of rehydrated WMP. Volatile compounds were extracted by high vacuum transfer (HVT) followed by separation into neutral/basic and acidic fractions. Aroma-active volatiles in each fraction were identified by gas chromatography olfactometry (GCO) and gas chromatography/mass spectrometry (GC-MS). The addition of RBO (0.5% w/v) had no effect on the sensory properties of WMP (P 0.05). Sensory changes in flavor occurred in both WMP (P < 0.05); however, a higher increase in painty/oxidized flavor was identified in the control sample after 40 days (P < 0.05). Volatile profile changes also occurred with storage time, but were not different between control and RBO-treated WMP. Our results suggest that the addition of 0.5% RBO does not drastically change the flavor profile of WMP over time, but does delay the development of oxidative off-flavors. The results also suggest that extended shelf-life, high-fat dried milk products can be developed as an ingredient for other dairy-based foods without significant flavor changes.

Session 71A, Dairy Foods: General
8:30 AM - 12:00 PM, Tuesday AM Room Hall I-2

2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana