Food Chemistry: X最新文献

Total antioxidant capacity (TAC) is an important indicator for assessing the merit of natural plants and foods. Herein, a visual TAC assay is developed based on the oxidase-like activity of nitrogen-doped carbon nanotubes loaded with Fe nanoparticles (FeNPs@NCNT), which is prepared via high-temperature pyrolysis of metal-organic framework precursors and can catalyze the oxidation of colorless o-phenylenediamine (OPD) to colored 2,3-diaminophenazine (DAP). The addition of antioxidants (e.g., quercetin) impedes the formation of DAP, diminishing the color change, which can be analyzed via the RGB values obtained with a smartphone color-recognition APP, "Color Picker". The change of the optical signal can also be analyzed in the fluorescence mode. These two detection modes yield consistent TAC analysis of actual plant samples, in accord with results from the standard ABTS method. Results from this study highlight the unique potential of nanozymes in the development of effective TAC analysis platforms for natural plants and food.

Herein, Adinandra nitida leaf polysaccharides (ANPs) were isolated, identified, and used as a particle emulsifier to stabilize Pickering emulsions. ANP was identified as a polysaccharide with a weight-average molecular weight of 383.10 ± 8.57 kDa that was mainly composed of galacturonic acid (43.94 ± 3.63 mol%), arabinose (17.44 ± 1.06 mol%), glucose (8.53 ± 0.65 mol%), and rhamnose (4.88 ± 0.32 mol%). The main glycosidic linkages included t-Ara(f)-(1→, →4)-Gal(p)-(1→, and →4)-Gal(p)-UA-(1→, with molar percentage ratios of 8.97 %, 19.68 %, and 47.05 %, respectively. ANP possessed a reducing power and ABTS radical scavenging ability. ANP could also reduce the interfacial tension between medium-chain triglycerides (MCT) and water in a concentration-dependent manner, demonstrating its emulsifying role. When the addition amount (c) ≥ 3 %, ANP could stabilize the O/W-type MCT-based Pickering emulsion gel with an oil-phase volume fraction of 70 %, and c was proportional to mechanical parameters such as gel strength, macroscopic viscosity index, and elastic index.

Steam explosion (SE) and cellulase treatment are potentially effective processing methods for Dictyophora indusiata by-products, for use in high-value applications. The treatment conditions were optimized by response surface methodology, increasing the soluble dietary fiber (SDF) yield by 1.52 and 1.16 times after the SE and cellulase treatments, respectively. The both treatments did not affect the functional groups and crystal types of the polysachharides, but both reduced the crystallinity. The SDF had a porous microstructure, which would increase the specific surface area and facilitates the adsorption of water and glucose, thereby improving its functional properties. SE and cellulase treatment significantly improved the hydration capacity of SDF; the glucose adsorption capacity increased by 1.15 and 1.07 times, respectively. Overall, the modified SDF showed different degrees of advantages in terms of yield, physicochemical and functionality. This study demonstrated that SE and cellulase are effective modification methods for SDF made from D. indusiata by-products.

Herein, the miniaturized thermal purge-and-trap (MTPT) device combined with self-calibration colorimetric/surface-enhanced Raman spectroscopy (SERS) dual-model optical sensors were designed for effective analysis of sulfur dioxide (SO₂) in wine. The SO₂ can be rapidly separated from wine and enriched by MTPT device, ensuring colorimetric/SERS dual-model optical sensing based on Karl Fischer reaction. The high separation efficiency of miniaturized MTPT device combined with self-calibration of dual-model optical sensors significantly alleviate matrix interference and improve the detection accuracy. The satisfactory linear range of 0.1-200.0 mg/L and 0.1-500.0 mg/L with limit of detection of 0.03 mg/L can be obtained. Finally, the MTPT-colorimetric/SERS method was applied to determine the content of SO₂ in different kinds of wine to verify the practicality. These results provide an ideal strategy in construction of MTPT device combined with self-calibration dual-model optical sensors for quantification of gaseous hazards in complex food samples with high rapidity, anti-interference and accuracy.

Metronidazole (MNZ) is one of the most commonly used antibiotics in the food industry. High levels in food can lead to the development of antimicrobial resistance in humans, so it is important to monitor its levels in food. In the context of legal proceedings, it is frequently necessary to re-examine samples after an extended period of time. It is therefore crucial to ensure that the analytes in question do not degrade during the storage period. In this study, HPLC-MS/MS approach was validated and used to analyze levels of MNZ and its hydroxy metabolite in chicken eggs during storage in the refrigerator (+4 °C) and in the freezer (-20 °C) for 3 months. An analyte solution was administered to hens to obtain eggs containing MNZ and hydroxymetronidazole (MNZ-OH). The dependence of the analyte content in eggs as a function of time after sampling was also investigated.

Food spoilage causes significant economic losses and endangers human health. Developing novel antimicrobial agents and preservatives is urgently needed for anti-foodborne diseases and improving food storage. Zhen Zhu Cai (Lysimachia) species are well-known edible plants among the East Asian populace that clear heat and anti-aging. Here, 70 fractions of ten Lysimachia species were compared, among which the bioactive fraction (KBZZC-05) was characterized and isolated to evaluate its antimicrobial activity, and compounds 21 and 23 were obtained under bioactive guidance. The KBZZC-05, 21, and 23 inhibited both spoilage organisms and foodborne pathogens (MICs = 2-256 μg/mL) better than potassium sorbate (MIC >256 μg/mL). It removed biofilms, causing surface morphology changes in bacteria. Additionally, KBZZC-05 (128 μg/mL) extended food shelf life through its antioxidant (P < 0.01 vs CK) and resistance to spoilage microorganisms. This study indicates that bioactive KBZZC-05 is a potentially non-toxic and eco-friendly botanical microbicide and preservative that can be used to treat foodborne diseases and for food storage.

The corn starch-protein complexes before postharvest ripening (JD-0) and after postharvest ripening (JD-40) were subjected to protease treatment, and the influence of protein on starch retrogradation was studied. Kinetic studies of starch retrogradation showed that protein reduced the retrogradation rate constant (k) of starch by 25.46 % (JD-0) and 7.48 % (JD-40), respectively. This was mainly reflected in the inhibition of short-range order, relative crystallinity and helix structure formation in the retrogradation process. In addition, low field strength nuclear magnetic resonance (LF-NMR) analyses also revealed that proteins inhibited starch retrogradation by isolating the precipitation of free water during retrogradation, causing the decrease in the viscoelasticity and firmness of the starch gel. Therefore, the inhibitory effect of proteins on starch retrogradation before postharvest ripening of corn-based food products was more relevant.

This study aimed to estimate the effects of chitosan/ corn starch (CH/ CS equal 62:38) film in combination with nettle essential oil nanoemulsions (0.41 wt% NEONEs) and starch nanocrystals (6 wt% SNCs) on the microbial and qualitative characteristics of the Eleutheronema tetradactylumfillets during refrigeration storage (4 ± 1 °C). The fillets were covered by biopolymeric films (CH/CS, CH/CS/SNCs, CH/CS/ NEONEs, CH/CS/SNCs/NEONEs). The qualitative analysis of refrigerated fillets was performed on days 1, 7, and 10. The incorporation of NEONEs and SNCs into CH/CS made an active film with antimicrobial effects. The decrease in pH (5.89 %), PV (44.72 %), FFA (10.41 %), TVB-N (35.01 %), TBA (27.07 %) and increase in moisture (5.38 %) were observed in the covered fillets by CH/CS/SNCs/NEONEs film in compared to uncovered fillets at 4 °C on day 10. The results revealed that incorporating SNCs (6 %) and NEONEs (0.41 %) into CH/CS could increase the storage time of the refrigerated fish fillets.

Flavor components largely depend on microbial activity and environmental conditions during traditional fermented food production. However, the microbial and abiotic contributions to the flavor of Chinese strong-aroma Baijiu (SAB) remain poorly understood. In this study, the composition and functional profiles of the fungal and bacterial communities changed significantly after fourteen days of grain fermentation. Acetilactobacillus jinshanensis, Issatchenkia orientalis and Kazachstani humilis became the dominant species as fermentation proceeded. Pathways related to lipid, protein and secondary metabolite metabolism were enriched during the middle and later stages of grain fermentation. Ethyl caproate, hexyl caproate, and ethyl lactate were identified as the main volatile components in fermented grain. Lactobacillus species were significantly related to volatile components. Compared with fungi, bacterial diversity accounted for 96 % of the variation in volatile components coupled with temperature, acidity and reducing sugar. This work provides insights into the production optimization and flavor enhancement of SAB by optimizing abiotic factors and microbial compositions.

Specialty coffee, typically lightly roasted, is valued for its unique fruity aroma. However, the fermentation process poses a risk of contamination with ochratoxin-producing fungi. This study aimed to select wild yeast strains capable of contributing distinctive flavor profiles while inhibiting the growth of ochratoxin-producing fungi. Coffee pulp served as a substrate to simulate yeast growth during coffee fermentation, allowing for the evaluation of yeast metabolites potential to inhibit spore germination in ochratoxin-producing fungi (Aspergillus niger). The findings demonstrated that the Saccharomyces cerevisiae strain effectively inhibited spore germination in A. niger. High-performance liquid chromatography (HPLC) analysis indicated that citric acid is likely the primary organic acid responsible for inhibiting A. niger spore germination. These results suggested that S. cerevisiae has potential applications in enhancing the food safety of coffee.