Chemical and Sensory Characterization of Oxidative Changes in Roasted Almonds Undergoing Accelerated Shelf Life

Abstract

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.

Non‐destructive characterization of egg odor and fertilization status by SPME/GC‐MS coupled with electronic nose

“…The relationship between fertilization status of hatching eggs and their VOCs was evaluated using multivariate analysis, such as O‐PLS, PCA, PLS, S‐PLS and cluster analysis. Multivariate analyses could present the distinction among UF, F, and IF eggs and indicate the relative importance of VOCs in explaining the variance of fertilization attributes . It was very clear that the VOCs from UF and Fd eggs were completely separated from each other in all multivariate models and there was an obvious separation trend of VOCs among UF, F, and IF eggs (Fig.…”

“…But it could not identify odor compounds as precisely as gas chromatography‐mass spectrometry (GC‐MS). Solid‐phase microextraction (SPME), which combines sampling, analyte isolation, enrichment, and clean‐up into one step, is a versatile, effective, and easily automated assay for VOC sample preparation . Gas chromatography‐mass spectrometry has been widely used to identify VOCs in food materials by advanced library searches …”

“…Solid-phase microextraction (SPME), which combines sampling, analyte isolation, enrichment, and clean-up into one step, is a versatile, effective, and easily automated assay for VOC sample preparation. 8,9 Gas chromatography-mass spectrometry has been widely used to identify VOCs in food materials by advanced library searches. [10][11][12] It is well known that identifying and removing infertile (IF) eggs at an early stage of incubation will benefit poultry hatcheries, especially if non-destructive tests are used.…”

Chemical changes in almonds throughout storage: modeling the effects of common industry practices

“…Almonds have been the largest specialty crop export in the United States (USDA, 2013). During storage, the physical and chemical quality of almonds will degrade and eventually result in consumer rejection (Franklin et al, 2017). Current industry practices include storing raw almonds in unlined cardboard cartons (UC), and roasted almonds either in polypropylene bags (PPB) or high barrier bags (HBB) (ABC, 2015).…”

“…Almond kernels have a compartmentalised microstructure that protects against oxidation, and evidence has shown this protective microstructure can be disrupted by roasting (Perren & Escher, 2013). A recent study investigated light roasted and dark roasted almonds and found that although peroxides proliferated at a greater rate in dark roasted almonds, consumer liking was not significantly different between light and dark roasted almonds (Franklin et al, 2017).…”