LWT - Food Science and Technology最新文献

Microbial lipids are a group of promising renewable sources that are highly demanded by the food, feed, pharmaceutical, and biofuel industries. Sporobolomyces pararoseus is a well-studied oleaginous yeast that is usually considered superior for the industrial production of microbial lipids over other conventional microorganisms. The objective of this study was to investigate the specific effect of hydrogen peroxide treatment on the biosynthesis of microbial lipids in S. pararoseus via lipidomics and transcriptomics technologies. These results showed that hydrogen peroxide treatment significantly enhanced lipid production in S. pararoseus CJR, especially the triacylglycerols. The up-regulation of several key lipogenic genes might be one of the main reasons for this enhancement. Integrative analysis of the lipidome and transcriptome revealed that some key protein-encoding genes and transcription factors might play a crucial regulatory role in lipid biosynthesis under hydrogen peroxide stress. Together, the results presented herein not only provided a feasible fermentation process for boosting the yield of certain lipids but also deepened our understanding of the lipid biosynthesis in S. pararoseus CJR. This could serve as a molecular cornerstone for enhancing their yield through genetic engineering and then further facilitate commercial applications of microbial lipids synthesized by S. pararoseus in more industrial sectors.

High internal phase emulsion gel (HIPEG) stabilized by food-grade protein particles has garnered increasing attention across various fields. However, the limited environmental stability in HIPEGs remain key challenges. In this study, oil-in-water HIPEGs stabilized by soy protein isolate and rutin complexes was used as a model system. The impacts of different conjugation conditions in preparing SPI and rutin (SPI-R) complex and various homogenization rates on HIPEGs formation were investigated. Results demonstrated that HIPEGs stabilized by covalent binding SPI-R complex exhibited excellent interfacial properties with more proteins involved in the formation of the HIPEGs at the interface compared to noncovalent-conjugate-stabilized HIPEGs. Notably, HIPEGs stabilized by SPI-R complex under alkaline conditions showed narrower size distribution and a more compact droplet structure along with a denser gel network and enhanced encapsulation efficiency of rutin compared to other groups. Moreover, the HIPEGs stabilized by these covalent conjugates exhibited better environmental stability and superior digestibility of protein. Specifically, HIPEGs stabilized by alkaline-conditioned SPI-R complex demonstrated excellent kinetically or thermodynamically stable state with minimal loss of stability under different environmental stresses when homogenized at an optimal rate of 15,000 rpm/min. This study provides valuable insights into utilizing protein-polyphenol particles as outstanding emulsifiers for food-grade HIPEGs.

Cracking fruit is a serious quality change phenomenon in the storage and transportation of postharvest plum fruit. To reduce the cracking rate of plum fruit during cold storage, the 'Guofeng No.7′ plum was sprayed with chitosan with 1.5% concentration 30d from preharvest. The postharvest plum fruit was stored at (0 ± 0.5) °C and (85–90) % relative humidity. The results showed that chitosan treatment could reduce the reactive oxygen species (ROS) level of plum fruit, effectively delaying the fruit cracking. Compared with the control, chitosan treated fruits inhibited the increase of free radical content such as O₂⁻· and H₂O₂ and delayed the increase of membrane permeability and the accumulation of MDA (from 71.9 mmol/g to 53.5 mmol/g). It also regulates lipoxygenase (LOX), peroxidase (POD), superoxide dismutase (SOD), catalase (CAT) (enzymatic activity from 34.15 g/min to 42.21 g/min) and ascorbate peroxidase (APX) activity and gene expression during fruit cracking to maintain membrane integrity and intracellular compartmentalization, thereby increasing the crack tolerance of plum fruit during cold storage. These results indicate that preharvest chitosan treatment can inhibit the metabolism of active oxygen species, increase the activity of ROS scavenging enzymes and gene expression, and delay the postharvest cracking of plum fruit.

To improve understanding of the potential benefits of quinoa as a staple food, the chemical composition, bioactive compounds, and total antioxidant capacity of six different colored quinoa cultivars were studied. The findings revealed that yellow quinoa exhibited a higher protein content, while white and red quinoa seeds contained greater amounts of starch, and black quinoa seeds were richer in fiber. A total of 20 phenolic compounds were identified, encompassing 13 phenolic acid variants and 7 flavonoid variants. The levels of phenolic acids (131.96–223.28 μg/g) and flavonoids (91.86–131.14 μg/g) exhibited variations based on seed color, with crimson and yellow quinoa seeds demonstrating the highest concentrations of both phenolic acids and flavonoids. Notably, crimson quinoa seeds displayed the highest content of betalains (36.17 μg/g). Saponin content was highest in yellow (178.82 mg/100 g), while the lowest in black (106.5 mg/100 g). Furthermore, it was observed that the phenolic acids present in red quinoa seeds exhibited the most potent DPPH free radical-scavenging ability. Conversely, black quinoa seeds displayed the highest iron-reducing antioxidant activity and ABTS free radical scavenging ability among all the samples examined. Moreover, black quinoa seeds demonstrated the highest overall antioxidant activity compared to other quinoa varieties This study suggests that colored quinoa seeds are rich in phenolic and betalains compounds with antioxidant capacity. The correlation analysis indicated a significant positive relationship between antioxidant activity and phenolic compounds up to a certain degree. As a result, colored quinoa can serve as an antioxidant food.

This study separated, purified, and identified mango polyphenol oxidase (PPO) in Xiaotainong mango, and the inactivation effect and possible inactivation mechanism of mango PPO by ultrasound (US) was investigated. The purified mango PPO, identified as Alfonso mango chloroplast PPO (NCBI number: XP:044462061.1), exhibited specific enzyme activity of 178,192 U/mg, with a yield of 1.2%, which was 9.85-fold higher than crude enzyme solution. Bioinformatics analysis of XP_044462061.1 indicated that the PPO consisted of a stable hydrophilic protein with a molecular weight of 66.77 kDa, an amino acid number of 593, and a structural domain similar to the TYROSINASE_1 (PS00497, tyrosinase) CuA and TYROSINASE_2 (PS00498; tyrosinase) CuB binding regions. The result showed that increased US treatment intensity and time better facilitated PPO inactivation, with a higher US intensity performing better than extended treatment time. US changed and disrupted the secondary and endogenous hydrophobic structures of the mango PPO, altered the exogenous hydrophobicity, and caused PPO molecule aggregation, ultimately leading to PPO inactivation. This article provided a theoretical basis for the application of US technology for processing mango products.

In Chinese dairy products, various saccharides including sugar substitutes are often added to modified milk or milk beverages to enhance flavor or increase benefits. That might result in the formation of furfural compounds due to the Maillard reaction between reducing sugars and proteins during heat treatment of milk. The contents of furfural compounds in dairy products vary depending on the type and proportion of sugars added, as well as the strength of heat treatment. Three monosaccharides, four disaccharides and two polysaccharides were selected to study the influences of saccharides on furfurals in modified milk. Kinetics parameters for the formation of furfural compounds were also studied under pilot processing conditions. The contents of furfurals in milk increased with the addition of monosaccharide, in the following order (from high to low) of type: fructose > galactose > glucose, and increased with the decrease in the polymerization degree of the added saccharides. The resulted prediction equations could be used to estimate the contents of furfurals in modified milk added with glucose, maltose or glucan after heat treatment at 115 °C–135 °C. This paper could provide a reference for the prediction and control of furfurals when applying saccharides in the dairy industry.

Tea is consumed worldwide and can reduce the risk of diabetes whereas the hypoglycemic compounds in tea remain unclear. Herein, the chemical compositions comparison and inhibition assays indicated that the inhibitory effect of tea against α-amylase was positively related with the enzyme-mediated oxidation degree of tea and black teas containing high contents of theaflavins exhibited the strongest in vitro inhibitory effect. Affinity selection-mass spectrometry-based high-throughput screening revealed that four theaflavins specifically bind to α-amylase. Compared to other compounds, theaflavins showed one order of magnitude higher in vitro inhibitory effects; thus, theaflavins are possibly the dominant α-amylase inhibitors in tea. A series of “α-amylase–theaflavins” interaction studies jointly demonstrated that theaflavins noncompetitively inhibit α-amylase activity by interacting with the amino acid residues of α-amylase and then inducing changes in the secondary structure. Furthermore, theaflavins (10 mg/kg/d) and black tea extracts (100 mg/kg/d) exhibited comparable hypoglycemic effects as acarbose in diabetic mice.

Hanseniaspora uvarum were isolated and characterized from various local environments to assess their production of fermentation-related enzymes, including β-glucosidase, esterase, pectinase and protease. Four H. uvarum strains with high enzyme activities were selected for further evaluation of their impact on Cabernet Sauvignon wines by analyzing enological parameters and untargeted metabolomics. Results showed that GS29 and GS38 strains improved aroma diversity and taste characteristics in co-fermentation, while GS36 strain only enhanced aromatic intensity and complexity. Metabolomics revealed that compared to S. cerevisiae, H. uvarum strains popularly reduced intermediate metabolites in glycolysis and TCA cycle, consumed more polypeptides, amino acids, and nucleotides, altered polyphenolic composition ratios, and decreased indole and derivatives. Our study highlights the application of three H. uvarum strains in co-fermentation to improve wine quality and provides insights into the metabolic regulation of each H. uvarum during co-fermentation like by adding intermediate metabolites or precursors.

To achieve fast on-site detection of shrimp allergens in food, this study established a new direct, fast, and real-time quantitative polymerase chain reaction (PCR) technology. The technology completed nucleic acid extraction in 4 min using a new nucleic acid releaser, and the DNA samples were detected using fast qPCR within 25 min (total detection was approximately 30 min). The results indicated that the direct fast qPCR can specifically detect shrimp, with a limit of detection of 0.0001% of shrimp in artificially simulated meat samples and a detection precision variation coefficient (CV value) was less than 5%. It successfully identified shrimp in different types of commercial food samples. As a simple, fast, and sensitive nucleic acid testing technology, it has broad application prospects for the on-site detection of shrimp allergens in food.