Browsing by Author "Dr. Tim Sanders, Committee Member"

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    The Effect of Microwave Blanching on the Flavor Attributes of Peanuts
    (2006-10-16) Schirack, Andriana Vais; Dr. MaryAnne Drake, Committee Member; Dr. Donn Ward, Committee Member; Dr. K.P. Sandeep, Committee Chair; Dr. Tim Sanders, Committee Member
    The use of microwave technology as an alternative blanching method for peanuts could potentially reduce energy costs and processing time, and lead to products with better nutrient retention. However, an off-flavor was found in peanuts which were microwave-blanched at high temperatures. As a result, the objective of this research has been to determine the impact of different microwave blanching parameters on the properties of roasted peanuts, and to characterize the off-flavor observed during high-temperature microwave blanching using a descriptive sensory panel and analysis of volatile flavor compounds. The processing parameters best suited for microwave blanching of peanuts were determined based on energy absorbed during processing, internal and surface temperatures, loss in moisture content, and blanchability. The best blanchability resulted from higher process temperatures and lower final moisture content. However, peanuts which reached the highest internal temperatures during blanching also developed an off-flavor, which was characterized by increased intensities of stale⁄floral and burnt⁄ashy notes. Solvent extraction ⁄ solvent assisted flavor evaporation (SAFE), gas chromatography-olfactometry (GC⁄O), gas chromatography-mass spectrometry (GC⁄MS), aroma extract dilution analysis (AEDA), threshold testing, and model systems were used to examine the chemical compounds which may be responsible for this microwave-related off-flavor. Analysis revealed an increased formation of guaiacol, phenylacetaldehyde, and 2,6-dimethylpyrazine in the off-flavored peanuts as compared to a process control, which led to the burnt and stale⁄floral characteristics noted by descriptive sensory panel. These compounds were only a small fraction of over 200 aroma-active compounds which were found to contribute to roasted peanut flavor using GC⁄O. This research illustrates the importance of the relative concentrations of the many aroma-active compounds found in peanuts. These findings could aid in training sensory panels to evaluate processing-related off-flavors, because guaiacol and phenylacetaldehyde could be used as chemical standards to define the burnt⁄ashy and stale⁄floral off-flavors which can occur during high temperature processing. Through this project, it was determined that it is possible to achieve acceptable blanchability in peanuts using microwave blanching while minimizing the possibility of an off-flavor.
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    The Roles of Fat and pH on the Detection Thresholds and Partition Coefficients of Three Compounds: Diacetyl, Delta-Decalactone, and Furaneol in Water, Oil, and Emulsions.
    (2009-01-08) Leksrisompong, Pattarin; Dr. Tim Sanders, Committee Member; Dr. MaryAnne Drake, Committee Chair; Dr. Allen Foegeding, Committee Member
    The effect of fat and pH on the best estimate threshold (BET) of 3 prominent dairy product flavor compounds with varying physicochemical properties: diacetyl, delta-decalactone, and furaneol, in water, oil and oil-in-water model emulsions (at 10 and 20 % fat at neutral and acidified pH 5.5) were investigated. The headspace-matrix partition coefficients (KHS/matrix) of each compound in the different matrixes were established. The rheology and particle size of the emulsions used in this study were also investigated. The particle size and the viscosity of the emulsions did not affect the BET or the partition coefficients. Reducing fat from 20 to 0 % did not affect the BET value or partition coefficient of diacetyl (P>0.05). Increasing fat content increased the BET value and decreased the partition coefficient (P<0.05) of the most lipophilic compound in the study, delta-decalactone. Fat did not affect the BET of furaneol (P>0.05) but did have an effect on the partition coefficient (P<0.05). At pH 7, addition of fat decreased the partition coefficient of furaneol whereas at pH 5.5, addition of fat increased the partition coefficient of furaneol. Adjustment of pH from 7.0 to 5.5 did not impact the BET values of delta-decalactone, but did affect the partition coefficients of furaneol at all fat levels and impacted diacetyl at 0 % fat. The partition coefficient results generally agreed with the BET values on the effect of fat and pH, although, the partition coefficient test was more sensitive to the differences in the matrix composition than a threshold test.