Food research international (Ottawa, Ont.)最新文献

To develop a safe, stable and easily absorbed new antioxidant peptide. The myofibrillar protein hydrolysates of Siamese crocodile meat were prepared and purified, their free radical scavenging and Fe²⁺ chelating ability were determined. The results showed that isolated component 3 of neutral protease hydrolysate (N₃) had the highest antioxidant activity. Subsequently, liquid chromatography-mass spectrometry was applied to appraise the amino acid sequences within the N₃ component, and 8 novel antioxidant peptides were screened by bioinformatics analysis, the antioxidant test proved that all 8 synthetic peptides had certain antioxidant activity. Among them, there was no significant difference in the DPPH radical scavenging capacity of GWDK, LWDK, ERWP, LGWK and LWAK (P > 0.05), which were higher than that of DFRDY and WYRDD (P < 0.05), the ABTS radical scavenging ability of DFRDY was similar to WYRDD (P > 0.05), but remarkably stronger than that of the other 6 peptides (P < 0.05). Finally, the binding mechanism of 8 novel peptides to Keap1 protein was explored through molecular docking, and it was found that hydrogen bonding and hydrophobic interaction were the primary forces that bind antioxidant peptides to Keap1 protein.

Fish maw, a traditional nutritious food, has significant development potential. However, the limited species sources and scarce research on processing characteristics present challenges. This study selected nine species of fish maws to determine their morphology and yield during hydrothermal treatment. Changes in nutritional composition, water migration, and structural characteristics between fresh and water-soaked fish maws were compared. All fresh fish maws had a dry basis protein content of more than 80 %, with no heavy metals, rich in functional and hydrophobic amino acids. After processing fresh fish maw into water-soaked fish maw, the fat and ash content decreased, while the relative protein content increased, and there was little change in the amino acid composition. Water distribution and texture properties indicated an initial rapid then slow water absorption rate for fish maw. After soaking, most bound and immobilized water transformed into free water, significantly enhancing cohesiveness, springiness, and chewiness. Hardness change varied among different species of fish maws due to inherent differences. Microstructural analysis revealed that the fiber bundle transitioned from an interlaced, tight structure to a porous network structure, with pore size and network distribution related to water migration and the texture characteristics of the fish maw. Among all species studied, freshwater silver carp and redfin culter fish maws demonstrated potential for further development.

Food safety caused by microbial contamination is an important problem that is difficult to solve for the food industry. In this study, a photocurable CFT hydrogel material is prepared by photocrossing casein with the flavin mononucleotide/sodium persulfate system, while flavin mononucleotide and tryptophan are used as photocatalysts to generate hydrogen peroxide (H₂O₂) for the inactivation of food pathogenic microorganisms. The CFT hydrogel demonstrated rapid gelation (<3 min), robust mechanical properties (1775 Pa), efficient H₂O₂ production (75 µM), and favorable biocompatibility. The CFT hydrogel could sterilize Gram-positive bacteria and Gram-negative bacteria after light irradiation, with sterilization rates exceeding 98 %. In addition, the CFT hydrogel showed great antibacterial activity to reduce E. coli on the surface of cherry tomatoes by 1.2 log. These unique properties make the CFT hydrogel a promising material for food preservation.

Based on the huge blank of thickened fluid staple food for people with dysphagia, multiple in vitro simulations were utilized to develop the thickened fermented rice milk. Here, the effect of amylase content, hydrolysis time and thickener content were considered. The rheological study and Cambridge throat evaluation revealed that hydrolysis could significantly reduce the viscosity and yield stress of fermented rice milk, accompanied by the decreased swallowing residue. The addition of thickeners increased the viscosity and cohesion of the fermented rice milk due to the entanglement network formation, which facilitated the formation of lubricating film, decreased the coefficient of friction, and improved the sensory score. Increasing thickener content from 0 % to 0.5 % induced the longer oral transition time (0.26 s to 0.45 s), more residue (0.85 g to 2.07 g) and shorter stretching length (850.42 mm to 313.62 mm) shown in the Cambridge throat simulation. Among them, the fermented rice milk with 0.40 % thickener showed the best sensory properties, and its swallowing properties evaluated by computer simulation also suggested concentrated frequency distribution of velocity, shear rate and viscosity without splashing or choking compared with the normal fermented rice milk, showing excellent swallowing safety.

The lack of sufficient flavour in perry represents a barrier to its further industrialization. This study aimed to investigate the effects of glutathione (GSH), β-glucosidase (Glu), and α-L-rhamnosidase (Rha) pretreatments, the fermentation temperature from 16 °C to 28 °C, and the aging time of 1, 2, and 3 years (PA1, PA2, and PA3) on the physicochemical properties, organic acids, and aroma profiles were investigated. The results demonstrated that the synergistic effect of Glu, Rha, and GSH was more effective than their individual or paired applications in enhancing the varietal aromas. The contents of terpenes, phenols, acetate and ethyl esters in the Glu + Rha + GSH treatment were significantly increased in comparison to the control, with improvements of 60.77 %, 118.64 %, 77.02 %, and 32.82 %, respectively. The OAV flavor profile showed rich floral, fruity, and citrus aromas. The contents of tartaric acid and quinic acid decreased from 16 °C to 28 °C, whereas lactic acid was the opposite. Except for phenethyl acetate and ethyl decanoate, the contents of acetate and ethyl esters exhibited a decline at elevated temperatures, whereas isopentanol and phenylethyl alcohol increased. The contents of esters and phenols at 16 °C increased significantly, whereas those of alcohols decreased. This contributed to banana, floral, fruity, orange peel, and spices aromas to the fermentation aromas. The difference in organic acid profiles between PA3 and PA1, PA2 were obvious, the contents of acetic acid and citric acid in PA3 decreased significantly, whereas those of tartaric acid, L-malic acid, and lactic acid increased. The contents and proportions of acetate and medium-chain fatty acid ethyl esters decreased from PA1 to PA3, while the ethyl esters resulted from esterification reactions increased, and the contents of alcohols and acids constituents were different between the three years. The contents of esters, phenols, and total volatiles increased significantly, while the aging aroma was markedly enhanced in PA3. It can be concluded that the Glu + Rha + GSH pretreatment, fermentation at 16 °C, and aging for three years exhibited the great aroma potential of perry, which enhanced the flavor intensity through the regulation of varietal, fermentation, and aging aromas.

Ya'an Tibetan tea, a dark tea with a rich historical heritage, is typically processed using two primary piling fermentation methods: wet piling with rolled leaves (moisture content around 60%) and dry piling with sun-dried or baked green tea leaves (moisture content below 30%). This study employed sensory evaluation, targeted and non-targeted metabolomics, and fungal Internal Transcribed Spacer (ITS) sequencing to investigate changes in quality components and fungal composition in Tibetan tea processed by both wet and dry-piling methods. The results revealed that 3,7-Dimethyl-1,5,7-octatriene-3-ol and D-limonene were identified as key volatile metabolites contributing to the aroma variations between the dry and wet-piled teas. More pronounced differences were observed in non-volatile components, with 407 differential metabolites identified between the wet- and dry-piled teas. Linear discriminant analysis effect size (LEfSe) identified Rhizomucor, Aspergillus, Thermomyces, Setophoma, and Debaryomyces as the key fungal genera with significant differences between the two piling methods, also dominating in abundance and playing a crucial role in the fermentation process of Tibetan tea. Correlation analysis between microbial communities and differential metabolites showed that Debaryomyces, Thermomyces, and Setophoma were significant contributors to the aroma differences between the teas produced by the two piling methods, while Rhizomucor and Aspergillus had a greater influence on non-volatile metabolites. Since Rhizomucor and Aspergillus were the most dominant fungi in the wet (63.05%) and dry-piled (68.70%) samples, respectively, and showed opposite correlations with major non-volatile differential metabolites, they may underlie the flavor differences between the two piled teas, such as mellowness, thickness, and sweet aftertaste. This study sheds light on the chemical and fungal mechanisms underlying the quality formation of Ya'an Tibetan tea processed by wet and dry piling methods, providing theoretical guidance for the improvement, standardization, and potential enhancement of production efficiency of Ya'an Tibetan tea production.

Green is no longer the only color used to describe tea leaves. As tea plants with different leaf colors-white, yellow, and purple-yield significant economic benefits, scholars are growing increasingly curious about whether these differently colored leaves possess unique aromatic characteristics. Headspace solid-phase microextraction (HS-SPME) combined with GC-MS was used to analyze the volatile metabolites of buds and leaves from 7 white-leaf tea plants, 9 yellow-leaf tea plants, 4 purple-leaf tea plants, and 7 normal (green) tea plants. A total of 125 aroma metabolites were identified. The aroma compounds of heterochromatic tea leaves and green-leaf tea were compared separately. It was found that white-leaf tea had the most upregulated compounds (63 up), mainly floral and fruity aromas, including nerol, Z-isogeraniol, and E-3-hexen-1-yl acetate. Purple-leaf tea had the most downregulated compounds (31 down), including β-myrcene, benzyl alcohol, and methyl salicylate, which are related to fresh and fruity aromas. According to variable importance in projection (VIP > 1) and a p-value < 0.05, a total of 40 differential compounds were detected, among which Z-3-hexenol, 1-nonanol, 2,4-di-tert-butylphenol, and 2,6,10,15-tetramethyl-heptadecane were common in all heterochromatic tea. The random forest model constructed using differential metabolites screened out five aroma metabolites, including Z-3-hexenyl isobutyrate, E-3-hexen-1-yl acetate, 2,4-di-tert-butylphenol, Z-jasmone, and Z-isogeraniol. These metabolites demonstrated high accuracy in the model (AUC = 1) and have the potential to serve as characteristic aroma compounds for distinguishing tea leaf colors.

With the increasing prevalence of diabetes, the search for natural compounds with potential anti-hyperglycemic effects has become a key focus in food and nutrition research. L-theanine (THE) and epigallocatechin gallate (EGCG) from tea are gaining attention due to their antioxidant and metabolic regulation properties. Although they have been shown to have an effect on glucose metabolism, their synergistic effect on starch digestive properties and the mechanism remain unclear. Here, we explored that THE and EGCG synergistically regulated starch digestive properties in ultrasound treatment through two different perspectives. At specific THE/EGCG ratios (THE/EGCG_1:1), maize starch granules exhibited significant aggregation and densification. THE promoted the ordered arrangement of starch molecular chains through hydrogen bonding, and the polyphenolic structure of EGCG further stabilised this ordered structure, thus enhancing the crystallinity and short-range ordering of starch. It meant that THE and EGCG further reduced starch digestibility by synergistically modulating the multi-scale structure of starch. In addition, THE and EGCG exhibited significant synergistic inhibition of α-amylase activity (1.6 mM THE and 0.05 mg/mL EGCG). The multi-spectral results showed that the addition of THE and EGCG enhanced the conformational change of the enzyme, leading to the change of the secondary structure, and the synergistic effect might originate from the multiple interactions of THE and EGCG with different amino acid residues in the digestive enzyme (e.g., THR-163, GLN-63, ASP-197, etc), which strengthened the inhibition, and the molecular dynamics simulations further supported the findings. This work promotes the further development and utilisation of endogenous substances in tea and provides some references for the development of food ingredients with potential hypoglycaemic functions.

The effect of an in vitro gastrointestinal assay on the characteristics of nanoparticles from food additives TiO₂ (E171) and SiO₂ (E551) present in confectionaries was determined by spICP-MS. No significant differences were detected in particle size distribution regardless of the phase of the in vitro stage and the confectionary products, with particles present as aggregates/ agglomerates. The percentage of TiO₂ as nanoparticle form was found to be less than 50 % during the in vitro gastrointestinal digestion process, whereas SiO₂ nanoparticles could not be detected due to the high LOD in size obtained (142 nm). The bioaccessible fractions of intestinal extracts showed a 5 % content for both particle types, suggesting their limited absorption in the body. MTT cytotoxicity assay with Caco-2 cells exposed to gastrointestinal extracts from confectionery products revealed an average cytotoxic effect of 40 % for all products tested which was attributed to the food matrix components rather than (nano)particles.

This study explored how setting conditions affect the gel properties of shrimp surimi from Solenocera crassicornis using a two-step heating process with varying temperatures (30, 40, 50 °C) and durations (0-120 min). At 30 °C, increased hydrogen bonds and cross-linking promoted macromolecular polymer formation, with optimal elasticity achieved at 15-30 min, but longer times led to gel aggregation and uneven structure. At 40 °C, macromolecular polymer decreased, while sulfhydryl groups increased, leading to disulfide bond formation, which disrupted hydrogen bonds and increased hydrophobic groups. Gel strength decreased over setting time, with a soft and smooth texture observed after 15-30 min. Setting at 50 °C disrupted chemical bonds, exposed hydrophobic groups, and resulted in less significant changes in storage modulus and loss modulus. After high-temperature gelation at 90 °C, disulfide bonds were further disrupted, reducing the stability of gel properties. Moreover, an increase in the setting temperature affected the internal water distribution within the shrimp surimi gel. A shorter setting time promoted the absorption of water molecules by starch in the gel, thereby reducing the free water content. However, when the setting time exceeded 60 min, the proportions of bound water and immobile water decreased, gradually transforming into free water. This transformation increased the drip loss and softened the texture of gel. In summary, setting conditions significantly influenced moisture distribution, viscoelasticity, and chemical forces in shrimp surimi gels.