Comparative study of accelerated assays for determination of equivalent days in the shelf life of roasted high oleic peanuts: Chemical and volatile oxidation indicators in accelerated and room temperature conditions

Determination of oxidative deterioration in edible oils by high-pressure photoionization time-of-flight mass spectrometry

Since lipid oxidation often causes serious food safety issues worldwide, determination of oil's oxidative deterioration becomes quite significant, which still calls for efficient analytical methods. In this work, high-pressure photoionization time-of-flight mass spectrometry (HPPI-TOFMS) was firstly introduced for rapid detection of oxidative deterioration in edible oils. Through non-targeted qualitative analysis, oxidized oils with various oxidation levels were successfully discriminated for the first time by coupling HPPI-TOFMS with the orthogonal partial least squares discriminant analysis (OPLS-DA). Furthermore, by targeted interpretation of the HPPI-TOFMS mass spectra and the subsequent regression analysis (signal intensities vs TOTOX values), good linear correlations were observed for several predominant VOCs. Those specific VOCs were promising oxidation indicators, which would play important roles as TOTOX to judge the oxidation states of tested samples. The proposed HPPI-TOFMS methodology can be used as an innovative tool for accurate and effective assessment of lipid oxidation in edible oils.

Infrared radiation blanching-inhibited browning and extended shelf life of pecan kernels

To evaluate infrared radiation (IR) blanching in comparison to conventional hot water (HW) blanching in inhibiting the browning and extending the shelf life of pecan kernels, the technology of IR blanching at 500-700 W for 90-45 s or HW blanching at 90°C for 60 s, and subsequently drying with hot air at 60, 70, and 80°C, respectively, was used, and then the activities of lipoxidase (LOX) and polyphenol oxidase (PPO), antioxidant capacities, color change, microscopic structure, and the shelf life of kernels were analyzed. Results showed that IR blanching not only significantly decreased the subsequent drying time but also effectively inactivated the activities of LOX and PPO, showing a lower residual activity of 15.74%-40.41% and 16.75%-56.25%, respectively. A higher retention of total phenolics was observed in kernels subjected to IR blanching, from 25.03 ± 0.04 to 29.50 ± 0.96 mg GAE/g compared with HW blanching (14.43 ± 0.07 mg GAE/g). Meanwhile, IR-blanched samples showed lower peroxide values, p-anisidine values, total color difference values, browning index, quinones contents, and lipofuscin-like pigments levels but had higher 2,2-diphenyl-1-picrylhydrazyl inhibition rate and better storage stabilities than HW-blanched samples. The technology of IR blanching at 600 W for 60 s followed by drying with hot air at 70°C for 40 min is suitable for producing pecan kernels with better qualities and a longer shelf life, through inactivating the endogenous enzymatic reactions and inhibiting the formation of lipofuscin-like pigments. PRACTICAL APPLICATION: Blanching is an essential pretreatment of food processing. Conventional blanching is achieved by hot water, which has some disadvantages of low-intensity enzyme inactivation, loss of water-soluble substances, etc. In this study, the potential of using infrared blanching, prior to drying, was studied to find solutions to improve the nutritional value, and the shelf life of pecan kernels. The results showed that infrared blanching at 600 W for 60 s followed by drying with hot air at 70°C for 40 min could inhibit the color degradation, improve the oxidation resistance, and prolong the shelf life of kernels.

CRISPR/Cas9-mediated editing of double loci of BnFAD2 increased the seed oleic acid content of rapeseed (Brassica napus L.)

Seed oleic acid is an important quality trait sought in rapeseed breeding programs. Many methods exist to increase seed oleic acid content, such as the CRISPR/Cas9-mediated genome editing system, yet there is no report on seed oleic acid content improvement via this system's precise editing of the double loci of BnFAD2. Here, a precise CRISPR/Cas9-mediated genome editing of the encoded double loci (A5 and C5) of BnFAD2 was established. The results demonstrated high efficiency of regeneration and transformation, with the rapeseed genotype screened in ratios of 20.18% and 85.46%, respectively. The total editing efficiency was 64.35%, whereas the single locus- and double locus-edited ratios were 21.58% and 78.42%, respectively. The relative proportion of oleic acid with other fatty acids in seed oil of mutants was significantly higher for those that underwent the editing on A5 copy than that on C5 copy, but it was still less than 80%. For double locus-edited mutants, their relative proportion of oleic acid was more than 85% in the T₁ and T₄ generations. A comparison of the sequences between the double locus-edited mutants and reference showed that no transgenic border sequences were detected from the transformed vector. Analysis of the BnFAD2 sequence on A5 and C5 at the mutated locus of double loci mutants uncovered evidence for base deletion and insertion, and combination. Further, no editing issue of FAD2 on the copy of A1 was detected on the three targeted editing regions. Seed yield, yield component, oil content, and relative proportion of oleic acid between one selected double loci-edited mutant and wild type were also compared. These results showed that although the number of siliques per plant of the wild type was significantly higher than those of the mutant, the differences in seed yield and oil content were not significant between them, albeit with the mutant having a markedly higher relative proportion of oleic acid. Altogether, our results confirmed that the established CRISPR/Cas9-mediated genome editing of double loci (A5 and C5) of the BnFAD2 can precisely edit the targeted genes, thereby enhancing the seed oleic acid content to a far greater extent than can a single locus-editing system.