Abstract: AbstractMilk fatty acids significantly contribute to human nutrition and clinical health. However, previous evidence for changes in the fatty acid profiles of different dairy species following homogenization and heat treatment is lacking. Here, changes in fat globule particle size and fatty acids in samples of Holstein, goat, buffalo, yak, and camel milk following homogenization (20 MPa) and heat treatment (63 °C for 30 min and 90 °C for 15 min) were investigated using a laser particle sizer and gas chromatography approach. The results indicated that the milk fat globule particle size of all studied dairy species significantly decreased after homogenization and heat treatment, in which there was no difference. The fatty acid composition of C10:0 and medium-chain fatty acid in goat milk, C18:0 and long-chain fatty acid in camel milk, and C16:0 in buffalo and yak milk served as the characteristic traits of these milks. Changes in the relative contents of several fatty acids (C4:0, C10:0, C16:0, C18:0, C18:1n9c, and C18:3n3) were dependent on homogenization, heat treatment, and the type of dairy species. In particular, C18:3n3 significantly decreased in goat and camel milk after homogenization and heat treatment. These findings provide new insights into how homogenization and heat treatment affect the fatty acid profile and can be used to further improve the heat treatment of milk from minor dairy species. PubDate: Mon, 28 Nov 2022 00:00:00 GMT DOI: 10.1093/fqsafe/fyac069 Issue No:Vol. 7 (2022)
Abstract: AbstractAlthough surface-enhanced Raman spectroscopy (SERS) substrates have achieved high sensitivity, it is still difficult to apply these SERS protocols to the on-site detection of real samples due to the SERS substrate being fabrication-complexed, unstable, reproducible, or unable to be applied in batch production. Here, a large-scale ordered two-dimensional array of Au nano-hemispheres was developed through electron beam vaporization of Au onto the easy-available commercialized anodic aluminum oxide (AAO) template with two-layer nanostructures of different diameters. The uniform Au nano-hemisphere is reliable for SERS detection of malachite green (MG) due to the relative standard deviation (RSD) of the SERS intensities at different locations less than 10%. With the optimized excitation wavelength, solvent effect and pH environment, the linear range of MG detection spans from 10–10 to 10–6 mol/L with a limit of detection (LOD) of 4×10–10 mol/L. The enhancement factor can reach 1.2×106. After extraction with acetonitrile and dichloromethane, MG in the spiked tilapia was detected with satisfactory recovery. The results indicate that the Au nano-hemisphere array can be expected to greatly facilitate SERS practical applications in detecting harmful food additives and chemicals due to the advantages of chemical inertness, physical robustness, simple fabrication, controllability, large-area uniformity, and large-batch production. PubDate: Fri, 28 Oct 2022 00:00:00 GMT DOI: 10.1093/fqsafe/fyac061 Issue No:Vol. 7 (2022)
Abstract: AbstractMelatonin (MT) is a low molecular weight compound with a wide variety of biological functions in plants. It is known to delay senescence in various fruits and vegetables. This study demonstrates that MT (100 μmol/L) delayed the senescence of pak choi stored at 20 °C. A total of 1121 differentially expressed genes (DEGs) were identified in an MT-treated group in comparison to untreated pak choi. Analysis of DEGs revealed that MT-induced delay in senescence involved reduction in the expression of chlorophyll metabolism genes and regulation of the expression of hormone-related genes and leaf senescence-related transcription factors. MT decreased the activity of chlorophyll metabolism-related enzymes Mg-dechelatase, pheophytinase, and pheide a oxygenase, decreased the concentrations of abscisic acid and jasmonic acid, and increased auxin concentration. MT delayed the impact of senescence-related transcription factors BcNAC41 and BcNAC87 on tobacco leaf senescence. This study provides an insight into the molecular mechanisms of MT-induced delay of postharvest senescence in pak choi and confirms its potential as a preservation technique. PubDate: Wed, 26 Oct 2022 00:00:00 GMT DOI: 10.1093/fqsafe/fyac064 Issue No:Vol. 7 (2022)
Abstract: AbstractIn this study, integrative metabolomics and transcriptomics analyses were conducted to investigate the effects of 1-methylcyclopropene (1-MCP) on apple fruit quality during long-term cold storage. The results showed that 1-MCP (1 μL/L) treatment could maintain fruits apparent quality (i.e. external color and firmness), inhibit the increase of rot rate and soluble solids content/titratable acidity ratio, decrease ethylene release, and respiratory intensity during cold storage, and extend shelf life. Moreover, 1-MCP had long-term effects on the accumulation of many qualities related to metabolite and gene expression in fruits. 1-MCP affected genes related to metabolism at the early stage of storage, specifically those of the glycolysis and tricarboxylic acid cycle pathways. Genes related to the degradation of sucrose, starch, and cellulose were inhibited, and some starch and cellulose synthesis genes were up-regulated by 1-MCP. Apart from ethylene synthesis and signal transduction being inhibited by 1-MCP, several enzymes (pectinesterase, pectate lyase, polygalacturonase) were involved in pectin degradation, and degradation products of the cell wall (i.e. d-galacturonic acid and d-glucuronic acid) were also strongly inhibited, further maintaining fruit firmness. Cysteine, as precursor glutathione (GSH) related to plant resistance, up-regulated the synthase gene. However, the expression of genes related to cyanoalanine synthase and amino acid utilization pathways was suppressed by 1-MCP. Collectively, 1-MCP could maintain the postharvest quality of apple fruits. PubDate: Sat, 22 Oct 2022 00:00:00 GMT DOI: 10.1093/fqsafe/fyac063 Issue No:Vol. 7 (2022)
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