18C-3 |
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A. V. SCHIRACK1, M. A. Drake2, T. H. Sanders2, and K. P. Sandeep2. (1) Dept. of Food Science, North Carolina State Univ., Schaub Hall, Box 7624, Raleigh, NC 27695-7624, (2) Dept. of Food Science, North Carolina State Univ., Schaub Hall, Box 7624, Raleigh, NC 27695-7624 The use of a continuous microwave system for peanut blanching has been proposed as a means of reducing processing time and energy costs compared to the traditional hot air, multi-zone oven. However, the periodic occurrence of an off-flavor described as dark sour aromatic (DSA) at higher blanching temperatures has been observed. The purpose of this research was to characterize the processing parameters leading to off-flavor formation and to identify the chemical nature of this off-flavor.The processing parameters examined were microwave power level, exposure time and peanut moisture content. Three methods of flavor identification were used: descriptive sensory analysis, static headspace, and solvent assisted flavor evaporation (SAFE) combined with GC-Olfactometry (GC-O) and GC/MS. Flavor differences between microwave-blanched and oven-blanched samples are evident, both by descriptive panel and by GC-O. The sensory panel observed low intensities of DSA and concurrent reductions in roasted peanutty and sweet aromatic notes in the microwave-blanched samples. No unique low molecular weight compounds or significant volatile concentration differences were identified by static headspace analysis in the off-flavor samples. The SAFE method was more suitable for identifying volatiles in peanuts. Through GC-O and GC/MS analysis, increased levels of (E,Z)-2,4-decadienal (fatty/floral aroma), hexanal (green/grassy), 2-heptanone (fatty/sour/brothy), and heptanal (fatty) and decreased levels of phenylacetaldehyde (rosy/honey) were observed in the off-flavor samples. The chemical identification of this off-flavor as well as the determination of the cause will enable prevention of the off-flavor and may ultimately aid in the adoption of microwave blanching. In addition, effective processing parameters for microwave blanching can be recommended.
Session 18C, Food Chemistry: Food composition, analysis and volatiles
2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana |