Abstract:Photodynamic antimicrobial technology (PDT), as a non-thermal physical bactericidal method, has received increasing attention due to its high efficiency, low residue, and lack of resistance induction. Natural pigments, as food-grade photosensitizers exhibit excellent optical responsiveness and biocompatibility. Studies have shown that curcumin, chlorophylls, and porphyrin-based pigments exhibit favorable photodynamic antimicrobial efficacy in various food matrices including fruits, vegetables, meat, and drinking water. The author summarizes the photodynamic antimicrobial mechanisms of representative natural pigments, and analyzes the effects of light parameters, photosensitizer concentrations, and food matrices on photodynamic antimicrobial efficacy. Furthermore, the recent progress of PDT applications in fruit and vegetable surface disinfection, drinking water sterilization, and smart packaging is reviewed, with a focus on the role of nanocarriers and composite films in enhancing photodynamic antimicrobial performance. Finally, the industrial application potential of natural pigment-mediated PDT in food processing is discussed, along with the challenges regarding photosensitizer stability and process standardization. Future research directions are proposed, emphasizing synergistic antimicrobial mechanisms and the development of functional materials for practical implementation.

Abstract:Gelatinization of dairy products has long been a common problem caused by heat-resistant protease contamination. Despite the high-temperature sterilization process, heat-resistant proteases secreted by Pseudomonas spp. can survive under extreme conditions. These enzymes can break down the peptide bonds of proteins in milk, resulting in the bitter taste and gelatinization of milk, which seriously affects the quality and shelf-life of dairy products. In view of the complex gelatinization mechanisms of dairy products and the lack of in-depth investigation, the author systematically outlined the characteristics, enzyme activity detection methods, and influencing factors of Pseudomonas spp. proteases, delved into the mechanisms underpinning the protease-induced gelatinization of dairy products, and summarized the control measures and novel regulatory strategies in the production process. The review is expected to provide a reference for the rapid identification of heat-resistant proteases and the inhibition of gelatinization of dairy products due to protease residues.

Abstract:Aflatoxin (AF), a notorious contaminant, has been a persistent challenge to the safety of edible oils. Prolonged exposure to low doses or acute consumption of high amounts of AF may induce serious health issues. Currently, no method can completely eliminate AF from edible oils. Therefore, it is crucial to explore strategies for reducing AF levels in edible oils. The measures to degrade AF from edible oils were reviewed, mainly including physical methods (such as high-temperature treatment, ray irradiation, and adsorption), chemical methods (such as ammonia fumigation and ozone oxidation), and biological methods (such as microbial degradation). In addition, this paper analyzed and discussed the principles, advantages, shortcomings, and safety of various degradation methods. Furthermore, it made an outlook on the development trend of AF degradation technology.

Abstract:Ellagic acid, a natural polyphenol, exists widely in plants and fruit tissue. It is mainly absorbed in the stomach and small intestine and produces multiple urolithins such as urolithin M5 and urolithin M6 under the metabolism of intestinal flora. With antioxidant, anti-inflammatory, anti-tumor, anti-aging, antimicrobial, blood glucose-lowering and other pharmacological effects, ellagic acid have important application and research value in the fields of functional food and medicine. The extraction methods, metabolism mechanisms, and pharmacological effects of ellagic acid and its application in functional food were reviewed. The difficulties in the application of ellagic acid in functional food were elucidated, and the future research focus was put forward. This review aims to provide a theoretical basis for the development and application of ellagic acid in functional food.

Abstract:[Objective] This study aims to determine the optimal solid-state fermentation conditions for the removal of zearalenone (ZEN) from corn gluten feed by Aspergillus niger (A. niger) FS10. [Method]With the removal rate of ZEN as the indicator, single-factor experiments and response surface method were employed to optimize the key fermentation parameters (inoculation volume-to-mass ratio, fermentation temperature, fermentation duration, and solid-to-liquid ratio). Furthermore, changes in mass fractions of key nutritional components in corn gluten feed before and after solid-state fermentation under the optimal conditions were analyzed. [Result] The optimal fermentation conditions were established as follows: an inoculation volume-to-mass ratio of 120 μL∶1 g, a fermentation temperature of 26 ℃, fermentation duration of 5.5 d, and a solid-to-liquid ratio of 1 g∶1.4 mL. Under these conditions, the removal rate of ZEN reached (70.04±1.88)%. The mass fraction of crude protein in corn gluten feed increased from (19.92±0.20)% before fermentation to (21.94±0.42)% after fermentation, while the mass fraction of total amino acids rose from (16.240±0.165)% to (18.510±0.034)%. [Conclusion]A. niger FS10 not only efficiently removes ZEN from corn gluten feed but also enhances its nutritional value as animal feed. The findings provide a scientific basis for the sustainable utilization and exploitation of corn gluten feed despite ZEN contamination.

Abstract:[Objective] To address the challenge of controlling harmful bacteria during the fermentation process of sausages, this study optimized the biofilm formation conditions of Lactiplantibacillus plantarum (L. plantarum) JB1 to enhance its competitive advantage in the low-temperature fermentation environment of sausages. Furthermore, this study systematically evaluated the regulatory role of the biofilm-forming L. plantarum JB1 in the quality and safety of sausages, aiming to provide process parameters and a theoretical basis for the development of high-stability probiotic formulations. [Method]Single-factor and orthogonal experiments were conducted to quantify the effects of the interactions between temperature, pH, carbon source, nitrogen source, metal ions, and buffer salts on the biofilm-forming L. plantarum JB1. A sausage fermentation model was employed to evaluate the effects of free-cell and biofilm-forming L. plantarum JB1 on microbial communities, biogenic amines, free protein hydrolysis, and sensory indicators of sausages. [Result] The optimal conditions for the biofilm formation of L. plantarum JB1 were a temperature of 37 ℃ and pH 6.5. The optimal culture medium was composed of 35 g/L maltose, 5 g/L peptone, 0.2 g/L Mn²⁺, and mass fraction 1.0% K₂HPO₄. Under these conditions, the biofilm formation of L. plantarum JB1 increased by 43.9% compared with that in the control group using the original MRS medium (P<0.05). In the 4 d fermentation of sausages, compared with the free-cell L. plantarum JB1, the biofilm-forming L. plantarum JB1 increased the lactic acid mass fraction by 8.5%, reduced the Enterobacteriaceae count by 16.5%, and decreased the total biogenic amine mass fraction by 7.7%. Moreover, it enhanced protein hydrolysis, resulting in increased mass fractions of small peptides and free amino nitrogen. In addition, the biofilm-forming L. plantarum JB1 increased the redness and decreased the lightness and yellowness of sausages. [Conclusion] Multi-factor synergistic regulation is key to the biofilm formation of L.plantarum JB1. Biofilm technology can specifically address safety risks during the fermentation stage, providing a new solution for the development of functional fermented meat products.

Abstract:[Objective] In view of the possible illegal addition of rose flavors (citronellol and geraniol) to Yunnan black tea, a method was established for rapid detection of citronellol and geraniol based on QuEChERS-gas chromatography-mass spectrometry (QuEChERS-GC-MS). [Method] >The procedure involved extracting Yunnan black tea samples with acetonitrile following water wetting. The extract was purified by QuEChERS dispersed solid phase extraction. It was detected under the selected ion monitoring (SIM) mode and quantified by the external standard method. [Result] Good linear relationships were observed for citronellol and geraniol within the mass concentration range from 0.05 to 5.00 μg/mL, with correlation coefficients (R²) greater than 0.999 for both compounds. The recovery rates under the spiked concentrations of 0.5, 1.0, 5.0, and 10.0 mg/kg fell within the range of 95.7% to 106.4%, with relative standard deviations (RSD) ranging from 0.77% to 6.58%. The method exhibited the limits of detection (LOD) of 0.22 mg/kg and 0.10 mg/kg and the limits of quantification (LOQ) of 0.74 mg/kg and 0.32 mg/kg. The method was then employed to analyze 29 suspected Yunnan black tea samples. The results showed high mass fractions of citronellol and geraniol in suspected samples, with the highest mass fractions recorded at 53.40 mg/kg and 68.33 mg/kg, respectively, which indicated illegal addition of flavors in Yunnan black tea. [Conclusion] It is a straightforward, reproducible, and precise method suitable for the rapid detection of citronellol and geraniol in Yunnan black tea.

Abstract:[Objective] This study aims to establish an efficient selenium biofortification strategy based on the liquid culture of Tremella aurantialba (T. aurantialba) mycelia to enhance its selenium enrichment capacity. [Method] The changes of growth phenotype, metabolic behavior, and selenium enrichment characteristics of T. aurantialba mycelia were analyzed during the Na₂SeO₃-induced selenium biofortification process in liquid culture. [Result] Addition of 5 mg/kg and 10 mg/kg Na₂SeO₃ promoted mycelium growth, whereas Na₂SeO₃ with the mass fraction exceeding 10 mg/kg significantly inhibited the growth of T. aurantialba mycelia, with the inhibitory effect intensifying as Na₂SeO₃ mass fraction increased. Therefore, 5 mg/kg and 10 mg/kg of Na₂SeO₃ were selected. With the selenium-enrichment level and the bioconcentration factor (BCF) of the T. aurantialba mycelia as the primary indicators, single factor and orthogonal experiments were conducted to optimize the selenium biofortification parameters. The results demonstrated that in the case of the Na₂SeO₃ mass fraction being 5 mg/kg, the optimal culture conditions for T. aurantialba mycelia were Na₂SeO₃ addition on the 4th day, inoculum volume fraction of 2.25%, pH 6, and rotational speed of 150 r/min. In the case of the Na₂SeO₃ mass fraction being 10 mg/kg, the optimal culture conditions were Na₂SeO₃ addition on the 3rd day, inoculum volume fraction of 2.25%, pH 7, and rotational speed of 125 r/min. Under these optimized conditions and the Na₂SeO₃ mass fractions being 5 mg/kg and 10 mg/kg, T. aurantialba mycelia achieved selenium-enrichment levels of 148.24 mg/kg and 239.47 mg/kg, respectively, representing increases by 26.45% and 38.71% compared with those before optimization. Furthermore, the BCF reached 68.42% and 51.05%, which indicated improvements by 53.89% and 55.31%. Additionally, the analysis of the nutrient composition of selenium-enriched T. aurantialba mycelia revealed that proteins were the primary binding agents for selenium (>60%). The addition of selenium not only preserved the nutritional value of T. aurantialba mycelial protein but also enhanced the levels of umami amino acids (aspartate and glutamate). Moreover, SeMet was found to be the predominant selenium form in T. aurantialba mycelia. [Conclusion] This study provides a reference for future endeavors in enriching selenium in T. aurantialba for both edible and medicinal purposes and developing natural dietary supplements containing selenium.

Abstract:[Objective] This study explores the nutritional quality of germinated rice, aiming to develop its medicinal value. [Method] Five varieties of rice ('Shuijing 3''Zhiyou 151''Chunyou 167''9 You 418', and 'Ningxiangjing 9') were treated with ultrasonic waves, and then lactic acid bacteria and fermentation liquid were used instead of water as the culture medium for rice germination. The effects of combined ultrasonication and lactic acid bacteria treatment on the levels of total starch, amylose, resistant starch, and soluble protein of rice during the germination process were investigated. The structural changes were analyzed by Fourier transform infrared spectroscopy and scanning electron microscopy, and the estimated glycemic index (eGI) was measured by in vitro simulated digestion experiment.[Result] The five varieties of rice reached a micro-germination state after 96 h of treatment, with the bud lengths ranging from 1.403 cm to 1.847 cm. The mass fractions of total starch, amylose, and resistant starch of five varieties of rice all showed a downward trend with the extension of germination time. After 96 h of germination, the mass concentrations of soluble protein of 'Zhiyou 151' and 'Ningxiangjing 9' were significantly lower than those before germination, while the mass concentrations of soluble protein of other varieties of rice showed no significant difference compared with those before germination. The Fourier transform infrared spectroscopy results showed that the infrared spectra of the five varieties of rice presented the same overall trend in five stages before and after germination. The absorption peak intensity at 3 500 cm^-1 of rice among different germination stages varied greatly and gradually decreased with the extension of germination time. The scanning electron microscopy results showed that with the extension of germination time, the smooth surface of rice gradually became rough and uneven. The results of the in vitro simulated digestion experiment showed that the eGI of five varieties of rice germinated for 96 h were all lower than 55, indicating that germinated rice was low-glycemic index (GI) food.[Conclusion] Germinated rice can effectively replace polished rice to address its high-GI concerns, and the germinated rice grains become softer, which is beneficial for the development and utilization of subsequent products.

Abstract:[Objective] This study was designed to elucidate the microbial community succession dynamics of rice straw and high-temperature Daqu at distinct stages of fermentation, investigate the associations between differential metabolites and dominant microorganisms, and preliminarily predict the sources and contribution of microorganisms in high-temperature Daqu. [Method] High-throughput sequencing combined with liquid chromatography-mass spectrometry (LC-MS) was used to analyze the variation patterns of microbial communities and metabolites during the fermentation of high-temperature Daqu. [Result] Pantoea and Pseudomonas were the dominant bacterial genera, while the dominant fungal genera were Mrakia and Nigrospora in new rice straw (XC). For mother rice straw (MC), Bacillus and Saccharopolyspora were identified as the dominant bacterial genera. At various fermentation stages, the dominant fungal genera were Thermomyces and Aspergillus, whereas the dominant bacterial genera were Saccharopolyspora, Acinetobacter, Bacillus, and Thermoactinomyces. LEfSe revealed no significant differences in the dominant bacterial taxa between high-temperature Daqu and rice straw. In contrast, a total of six differential fungal taxa were collectively identified through co-analysis. Among them, Alfaria and Myriococcum were recognized as the marker fungal specific to rice straw, while Pichia、Saccharomyces、Monascus, and Kodamaea were the representative marker fungal in high-temperature Daqu. Source Tracker-based source tracking analysis indicated that the bacterial contribution of rice straw to high-temperature Daqu was negligible across different stages, whereas the fungal contribution varied among stages. Notably, the second-turn rice straw (EFC) exerted the highest fungal contribution to the detached Daqu (CQQ). Metabolomic profiling revealed 197 differential metabolites between rice straw and high-temperature Daqu. The correlation network between these differential metabolites and dominant microorganisms underpinned the fundamental biological regulatory mechanisms governing the fermentation process. [Conclusion] This study establishes a foundation for subsequent investigations into the fermentation mechanism of high-temperature Daqu and for enhancing the controllability of traditional fermentation processes.

Abstract:[Objective] This study aims to investigate the effect of the energy blending formula with caffeine as the major component on mood improvement. [Method] A total of 240 participants were assigned into an experimental group and a control group, with 120 participants in each group. The experimental group consumed the drink containing energy blending formula with caffeine as the major component, and the control group consumed the same flavor drink without this energy blending formula. The Profile of Mood States (POMS) scale was used to assess mood states. Participants completed the scale at four time points: before consumption and at 30, 60, and 90 min post-consumption. [Result] The experimental group exhibited a significant increase in vigor and a notable reduction in fatigue and tension at 30 min post-consumption, showing improved overall mood state (P<0.05). The depressive mood was reduced in the experimental group at 60 min post-consumption (P<0.05). [Conclusion] The energy blending formula with caffeine as the major component significantly improves mood states, which provides theoretical basis for the development of functional beverage formulas.

Abstract:[Objective] This study aims to explore the quality and umami changes of Ruditapes philippinarum during cooking. [Method] The cooking loss rate, texture, amino acid nitrogen, free amino acids, flavor nucleotides, glycogen, and sensory quality of Ruditapes philippinarum were measured after cooking (at 85, 90, 95, and 100 ℃ for 1, 2, 3, 4, and 5 min). [Result] At the same cooking temperature, the cooking loss rate and hardness of Ruditapes philippinarum increased with the increase in cooking time. At the cooking temperatures of 90 and 95 ℃, the mass fractions of amino acid nitrogen in Ruditapes philippinarum generally presented a decreasing trend as the cooking time increased within 1 to 5 min. At the same cooking temperature, the mass fractions of umami amino acids in Ruditapes philippinarum generally showed a decreasing trend as the cooking time increased within 1 to 4 min. When the cooking time was the same, the mass fractions of umami amino acids and the equivalent umami concentration (EUC) in Ruditapes philippinarum generally exhibited a decreasing trend with the rise in cooking temperature. When cooked for 2 min, the glycogen was fully degraded, leading to a relatively high mass fraction of succinic acid and a good umami presentation. The total sensory evaluation score of Ruditapes philippinarum reached its highest, and the umami score was comparatively high after cooking at 90 ℃ for 2 min. [Conclusion] Based on results of taste and quality, it was determined that the best umami of Ruditapes philippinarum was achieved when cooked at 90 ℃ for 2 min. The findings provide a theoretical basis for the processing quality and umami retention in freshly cooked Ruditapes philippinarum.

Abstract:[Objective] This study explored the effects of steaming/boiling time and cutting size on the color, texture, starch structure, and anthocyanin mass fraction of red and purple potatoes before and after cooking, aiming to provide a theoretical basis for the processing of colored mashed potatoes. [Method] Red and purple potatoes were taken as the research objects. They were cut into three different sizes (30 mm×30 mm×10 mm, 20 mm×20 mm×10 mm, and 16 mm×16 mm×10 mm) and steamed or boiled for five time periods (0, 3, 5, 7, and 10 min). The color parameters (including surface brightness L^*, red-green value a^*, and yellow-blue value b^*), texture properties (hardness, viscosity, chewiness, and adhesiveness), starch structure, and anthocyanin mass fraction were measured before and after steaming/boiling. The effects of steaming/boiling time and cutting size on the texture, starch gelatinization, and anthocyanin mass fraction of mashed potato were analyzed. [Result] Steaming/boiling time and cutting size had significant effects on the color, especially the L^*, a^*, and b^* values, of red and purple potatoes. With the extension of steaming/boiling time, the hardness, viscosity, chewiness, and adhesiveness of red and purple potatoes of all three cutting sizes showed a downward trend. Compared with steaming, boiling was more likely to cause the declines of these texture indicators. For potatoes with a cutting size of 30 mm×30 mm×10 mm, their texture indicators were significantly higher than those of smaller blocks (20 mm×20 mm×10 mm and 16 mm×16 mm×10 mm) under the same steaming/boiling time. For the blocks that could be made into mashed potato, steaming/boiling time and cutting size had greater impacts on the viscosity and chewiness of red mashed potato, but had no significant effect on those of purple mashed potato. Extending the steaming/boiling time to 10 min accelerated the starch gelatinization process, disrupted the starch structure, and caused a decrease in anthocyanin mass fraction. [Conclusion] The optimal processing conditions for colored potatoes are as follows: boiling for 7 min and cutting into blocks of 16 mm×16 mm×10 mm. The colored mashed potato prepared under these conditions has the best color and texture and can meet the quality requirements for the processing of colored mashed potato.

Abstract:[Objective] This study aimed to investigate the effects of different freezing preservation techniques on the quality of sea buckthorn (Hippophae rhamnoides) leaves. [Method] A low-voltage electrostatic field (LVEF) pretreatment was applied during the freezing process of sea buckthorn leaves, and its effects on freezing characteristics and bioactive compound retention were evaluated. Field strengths at 0, 20, 40, and 60 cm from the discharge plate were compared with conventional freezing in terms of freezing rate, water loss rate, bioactive compound retention rate, and antioxidant activity of sea buckthorn leaves. The optimized and conventionally frozen leaves were subsequently used to prepare sea buckthorn leaf yogurt, with plain yogurt (NY) as the control. Physicochemical indexess of the yogurt samples were determined. [Result] LVEF treatment at a distance of 20 cm shortened the freezing time by 16.6% and reduced the moisture loss rate to 12.07% compared with conventional freezing. The retention rates of flavonoids and polyphenols reached 85.27% and 90.97% of those in fresh leaves, respectively. In addition, the treated samples also exhibited strong DPPH and ABTS radical scavenging activities at low concentrations and promoted the conversion of free water into bound water, mitigating ice crystal damage. The yogurt prepared with LVEF-treated leaves (LY) showed increases of 10.60% and 15.70% in flavonoid and polyphenol content, respectively, compared with that prepared from conventionally frozen leaves (FY), along with enhanced antioxidant activity (P<0.01). [Conclusion] LVEF-assisted freezing effectively preserves the bioactive compounds and improves the freezing quality of sea buckthorn leaves, providing theoretical support for their industrial-scale preservation.

Abstract:[Objective] This study aims to assess the quality of Tieguanyin oolong tea during the baking process. [Method] Near-infrared spectroscopy was used for non-destructive detection of Tieguanyin oolong tea during the baking process and chemometrics was employed to analyze the changes in the intrinsic quality of the Tieguanyin oolong tea. Spectral preprocessing and dimensionality reduction were conducted for the near-infrared spectral data. Support vector machine (SVM) and back propagation neural network (BPNN) were adopted to construct discrimination models for the baking degree of Tieguanyin oolong tea. Combining the near-infrared spectral data with intrinsic quality data, partial least squares regression (PLSR) was employed to build quality prediction models. [Result] According to the changes in intrinsic quality and sensory evaluation results, the baking degree of Tieguanyin oolong tea can be graded into under baking, moderate baking, and over baking. Under the full-spectrum spectral data model, with preprocessing as multiple scatter correction (MSC) and the discriminant model as BPNN, the discriminant effect was the best, and the accuracy rate of the test set was 100.00%. When predicting the four intrinsic quality properties, the prediction model combining the successive projections algorithm (SPA) with PLSR had the best accuracy. The determination coefficients of prediction (RP2) of the best prediction model for free amino acids, tea polyphenols, catechins, and caffeine were 0.949 6, 0.944 3, 0.950 8, and 0.740 0, respectively. [Conclusion] This study realized the accurate discrimination of the baking degree and the rapid prediction of quality of Tieguanyin oolong tea, providing a theoretical foundation for the accurate discrimination and control of oolong tea baking.

Abstract:[Objective] This study aims to achieve the efficient biosynthesis of 4-hydroxyisoleucine (4-HIL) in Corynebacterium glutamicum (C. glutamicum). [Method] The isoleucine (Ile) inducible promoters (P_brnFEN) of varying strengths were used to dynamically upregulate the expression of the isoleucine dioxygenase (IDO) gene ido and the Vitreoscilla hemoglobin (VHb) gene vgb. On this basis, constitutive promoters of different strengths were employed to enhance the expression of the phosphoenolpyruvate carboxylase (PEPC) gene ppc and the pyruvate carboxylase gene pyc. [Result] Among the recombinant strains harboring different P_brnFEN promoters, strain C. glutamicum SN-I₇V₇ (SN-I₇V₇) was selected. After 144 h of fermentation with this strain, the concentration of 4-HIL reached (109.14±1.03) mmol/L, representing a 46.69% increase compared with the control strain C. glutamicum SN02 (SN02). Subsequently, overexpression of ppc with the strong promoter P_tacM led to the development of strain C. glutamicum RS-MP (RS-MP), an elite 4-HIL producer. This strain achieved a 4-HIL concentration of (145.76±6.04) mmol/L, a 33.55% improvement over the control strain SN-I₇V₇. [Conclusion] The screened P_brnFEN combinations and the ppc overexpression strategy provide a theoretical basis for the efficient biosynthesis of 4-HIL in C. glutamicum.