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This study was carried out to investigate the applicability of nonthermal plasma (NTP) technology for the pasteurization of almonds. Almonds were spiked with various levels of Escherichia coli by dipping the almonds in E. coli culture broth followed by drying. The spiked almonds were treated with NTP under different treatment conditions. The pattern of the microorganisms reduction by NTP was analyzed. NTP was found to be effective on reduction of E. coli on almond evidenced by almost 5-log reduction after 30-sec treatment at 30 kV and 2000 Hz. The NTP bactericidal effect on E. coli inoculated on almond increased with the applied voltage and the frequency. The NTP reduction followed the 1st-order reaction kinetics, and the reduction rate constants varied with almond types and grades. The E. coli cells at logarithmic phase were more sensitive to the NTP than those at stationary and declining phases.

In almonds, there is no standard method for detecting oxidative changes and little data correlating consumer perception with chemical markers of rancidity. To address this, we measured peroxide values (PV), free fatty acid values (FFAs), conjugated dienes, tocopherols, headspace volatiles, and consumer hedonic response in light roasted (LR) and dark roasted (DR) almonds stored under conditions that promote rancidity development over 12 months. Results demonstrate that, although rancidity develops at different rates in LR and DR almonds, consumer liking was not significantly different between LR and DR almonds. Average hedonic ratings of almonds were found to fall below a designated acceptable score of 5 ("neither like nor dislike") by 6 months of storage. This did not correspond with recommended industry rejection standard of PV < 5 mequiv peroxide/kg oil and FFA < 1.5% oleic. FFAs remain well below <1.5% oleic during storage, indicating that FFAs are not a good marker of rancidity in roasted almonds stored in low humidity environments. Regression of consumer liking to concentration of rancidity indicators revealed that selected headspace volatiles, including heptanal, octanal, nonanal, 2-octenal, 2-heptanone, 2-pentylfuran, hexanal, and pentanal, had a better correlation with liking than did nonvolatile indicators.

A unique comprehensive sensory lexicon for describing the appearance, aroma, flavor and texture attributes of almonds was developed by a nine‐member panel with extensive experience in descriptive analysis. The almond lexicon was then used to profile the sensory properties of 20 almond samples obtained from three growing regions in California over two harvest years and encompassing seven major almond varieties, to better understand the natural variability in raw almonds. Range graphs were plotted to depict the intensity range (minimum to maximum score) for a given attribute across all samples evaluated for a variety. Descriptive analysis results revealed that the major almond varieties tested had a range of inherent variability and that specific varieties had unique attributes. Distinct walnut, tea and squash flavor aromatics were detected in only some almond varieties. Appearance, aroma, basic taste and chemical feeling factor attribute ranges were generally small and consistent among varieties. PRACTICAL APPLICATIONS The detailed, working almond lexicon created in this study will provide researchers, producers and manufacturers with an effective platform to communicate observations for the evaluation of almonds. The sensory attribute assessment of almond varieties obtained from different regions, growers and harvest years allows for a better understanding of the natural variability in almonds. Establishing the range of natural variability found in raw almonds of the major California varieties provides the basis for future research on the effects of processing treatments on the sensory characteristics of almonds.

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