Abstract:Due to the increasing number of cancer patients and the decreasing effectiveness of conventional drugs on drug-resistant cancer cells, there is a growing demand for new anti-cancer drugs in the medical field. Some bioactive peptides (BAPs) have good anti-cancer activity and are known as anti-cancer peptides (ACPs). They are widely available and have potential medical application prospects. Cancer cells, due to their unique metabolic pathways, create a microenvironment different from normal tissue and develop immune escape abilities. ACPs exhibit anti-cancer activity by disrupting cancer cell membranes, regulating cancer cell growth and proliferation, and other pathways. However, due to their small molecular weight and exposed structure, ACPs are difficult to maintain stability in the complex environment of the body, and thus their effectiveness is inevitably lost, which poses certain difficulties for developing efficient products and requires a certain degree of combination or protection. The author introduces the food sources of ACPs and explains the anti-cancer activity and molecular mechanisms of ACPs. Considering the effectiveness of ACPs in directly attacking or indirectly hindering cancer cells, the author summarizes the usage and development potential of ACPs in new anti-cancer drug matrices, providing a reference for the application of food-derived ACPs in the medical field.

Abstract:[Objective] With Streptomyces noursei GX6 (S. noursei GX6) as the starting strain, strain breeding was carried out to increase the yield of ε-poly-lysine (ε-PL) and solve the problem of sporulation ability degradation of the mutant strain. Then, pH regulation of fermentation was employed to further increase the ε-PL yield of the mutant strain.[Method] Ion implantation mutagenesis combined with multi-antibiotic resistance screening was carried out for S. noursei GX6, and high-yield mutant strains of ε-PL were screened. Then, the components and their mass concentrations of various culture media were optimized for cultivating the high-yield strain, and the sporulation was observed. Finally, fermentation experiments with constant pH and pH shocks were carried out in a 5 L fermenters.[Result] The high-yield mutant strain S. noursei T9 obtained through breeding had a ε-PL yield of 2.97 g/L in shake flasks. The use of the MGY medium (containing soybean powder, mannitol, glucose, yeast extract, and CaCO₃) effectively restored the sporulation ability of S. noursei T9. Moreover, this strain maintained genetic stability after 10 passages. During the fed-batch fermentation with constant pH 4.0 in the fermenter, the ε-PL yield of S. noursei T9 reached 56.8 g/L, which was 20.3% higher than that (47.2 g/L) of S. noursei GX6. When the pH shock strategy was further adopted, a single shock increased the ε-PL yield to 62.1 g/L, with an increase of 9.3%, while two pH shocks further increased the ε-PL yield to 69.5 g/L, with the production efficiency reaching 0.006 3 g/(g·h).[Conclusion] This study provides practical strategies for addressing the insufficient sporulation capacity and increasing the ε-PL yield of S. noursei in industrial production.

Abstract:[Objective] To explore the covalent modification effects of 2-enal and dienal derived from the oxidation of docosahexaenoic acid (DHA) on bovine serum albumin (BSA) and their influences on the protein structure. [Method] The formation of aldehyde-protein adducts was analyzed by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The level of protein carbonylation was determined by 2,4-dinitrophenylhydrazine (DNPH) colorimetry. The changes in protein secondary structure were analyzed by Fourier transform infrared spectroscopy (FT-IR) and ultraviolet-visible absorption spectroscopy. [Result] The adducts formed by dienal with histidine and lysine residues in BSA were significantly more than those formed by 2-enal. With the increase in aldehyde concentration, the carbonylation level of BSA rose significantly. Aldehyde modification led to reduced α helices and increased β folds of BSA. The ultraviolet-visible absorption spectrum showed a hyperchromic effect, indicating that the protein underwent unfolding and intermolecular cross-linking. [Conclusion] The aldehydes derived from the oxidation of DHA can induce structural disorder and oxidative damage of BSA through covalent modification. This study provides a theoretical basis for improving the oxidative stability of protein carriers in polyunsaturated fatty acid preparations and has important reference value for understanding the quality deterioration mechanism of foods rich in polyunsaturated fatty acids during processing and storage. In addition, it provides data support for the development of strategies to inhibit protein oxidation and extend the shelf life of food.

Abstract:[Objective] This study aimed to explore the probiotic properties of Lactiplantibacillus plantarum (L. plantarum) ALAC-G2 and the inhibition mechanism of its antifungal peptide AFP against Candida albicans(C. albicans). [Method] The probiotic properties of L. plantarum ALAC-G2 were evaluated by in vitro experiments, including self-aggregation ability, cell surface hydrophobicity, acid tolerance, bile salt tolerance, and artificial gastrointestinal fluid tolerance. The inhibition mechanism of AFP against C. albicans was analyzed by determining the minimum inhibitory concentration (MIC), growth curve, cell wall and membrane permeability, hyphal phase transition, and biofilm formation of C. albicans. [Result] L. plantarum ALAC-G2 had a self-aggregation ability of 59.70% and a surface hydrophobicity of 21.43%, and it showed good tolerance to acid, bile salt, and artificial gastrointestinal fluid, showcasing good probiotic potential. The MIC of AFP against C. albicans was 16 mg/mL. AFP not only effectively inhibited the growth and reproduction of C. albicans but also caused damage to integrity of the cell wall and cell membrane, weakened the ability of transforming into the hyphal form, and significantly inhibited the adhesion and biofilm formation of the fungus. [Conclusion] This study clarified the probiotic functions of L. plantarum ALAC-G2 and the inhibition mechanism of the antifungal peptide AFP it produces, providing important technical support for the innovative application of this strain in food preservation and the development of intestinal microecological regulators.

Abstract:[Objective] This study aimed to optimize the formulation and investigate the flavor profile of composite lotus root juice, addressing the limitations of monotonous flavor and physical instability (precipitation). [Method] The composite lotus root juice was prepared with lotus root juice as the primary ingredient and supplemented with Dendrobium officinale leaf juice, apple juice, white granulated sugar, and xanthan gum. On the basis of single-factor experiments, a multi-index evaluation system was constructed through the analytic hierarchy process and the entropy weighting method. The formulation was optimized via response surface methodology coupled with a genetic algorithm. Furthermore, multi-dimensional flavor characterization was performed by gas chromatography-ion mobility spectrometry (GC-IMS), electronic nose, and electronic tongue. [Result] The optimal formulation for the composite lotus root juice was composed of 24% (mass fraction) Dendrobium officinale leaf juice, 0.14% (mass fraction) xanthan gum, and 6% (mass fraction) white granulated sugar. The comprehensive sensory score of the composite lotus root juice prepared with the optimal formulation reached 0.947±0.028, with a high degree of consistency between the predicted and experimental values. Flavor analysis indicated that compared to the control group, the optimized formulation exhibited significant increases in the proportions of key volatile flavor compounds, particularly aldehydes and ketones. Electronic sensor and electronic tongue confirmed that the optimized group possessed a fresh and harmonious aroma with reduced pungent odors. Additionally, bitterness was effectively suppressed, while umami and richness were significantly enhanced. [Conclusion] The optimized formulation achieves the synergistic improvement in aroma enhancement, bitterness reduction, and physical stability.

Abstract:[Objective] This study prepared full-length and fragment antibodies of bovine immunoglobulin G (IgG) with a mammalian cell recombinant expression system and screened high-affinity nanobodies that specifically recognize bovine IgG based on phage display technology, aiming to provide new antibody tools for the detection and functional study of bovine IgG. [Method] By retrieving the bovine IgG gene sequences, the CH fragment, Fc fragment, CH3 fragment, and CL fragment of bovine IgG were cloned into the pTT5 eukaryotic expression vector and efficiently expressed in Expi293F cells. With natural bovine serum and recombinant Fc fragment as coating antigens, three rounds of biopanning were performed to screen for the nanobodies that specifically bound bovine IgG from a phage-displayed nanobody natural library. Positive clones were induced for expression in Escherichia coli Rosetta, and their specificity to IgG of other species as well as binding sites were determined. [Result] The expression vectors for the CH fragment, Fc fragment, CH3 fragment, and CL fragment of bovine IgG were constructed, and efficient recombinant expression of full-length bovine IgG as well as heavy and light chain fragments was achieved in Expi293F cells. The specific nanobodies recognizing bovine IgG were successfully screened from a phage-displayed natural nanobody library through biopanning with natural bovine serum as the target and prepared. [Conclusion] On the basis of phage display technology, two nanobodies with high specificity targeting bovine IgG were screened through a three-round biopanning strategy, and their recombinant expression and activity verification were successfully completed. This can provide a reference for subsequent adulteration detection in milk or beef products.

Abstract:[Objective] To uncover the risk of rice mildew and ensure cereal security, this study compared the surface and endophytic fungal community characteristics in rice under granary storage and simulated storage with high humidity in Zhejiang to explore the predominant fungi and potential toxigenic fungi under the two storage conditions. [Method] Cultivable molds in rice samples were identified by plate culture, morphological observation, and ITS sequencing, and fungal community diversity of rice was investigated by high-throughput sequencing. [Result] Compared with that at the early storage stage, the mold number of samples during late stage of granary and simulated storage increased by 7.05% and 12.03%, respectively. Although Ascomycota was a dominant phylum in rice under the two storage conditions, the predominant cultivable molds were Curvularia (35.66%) and Penicillium (51.13%), respectively. The relative abundance difference of Penicillium reached 42.7%. Alternaria was a common predominant genus of surface fungi and endophytic fungi in rice under granary storage, and the relative abundance of endophytic Alternaria (39.85%~91.51%) was higher than that of surface ones (14.33%~30.53%). In the rice under simulated storage, Alternaria (<32.32%) was the common predominant genus of surface fungi and endophytic fungi at the early storage stage, while Aspergillus (<15.01%) was the predominant genus after storage for 3 months, which indicated an alteration of predominant fungi during storage. In addition, the relative abundance of Fusarium solani secreting deoxynivalenol (DON) decreased by 3.10% and 2.46% in rice under granary and simulated storage over time, respectively. In addition, Hypocrea, Sarocladium, and Alternaria were identified as marker genera in rice under granary storage, while Wallemia and Aspergillus might be used as marker genera in rice under simulated storage rice at different stages. [Conclusion] The mold number of rice under storage significantly increased, and Alternaria was identified as a predominant genus in rice under both storage conditions. The high humidity increased the relative abundance of Aspergillus in both surface and endophytic fungi. The potential toxin-producing fungi Alternaria and Aspergillus were the two marker genera in rice under the two storage conditions, respectively. The findings provide a theoretical basis for controlling rice mildew and toxin accumulation.

Abstract:[Objective] This study aimed to determine the optimal fermentation conditions for sweet potato kombucha and analyze changes in functional components and in vitro antioxidant activity of the product. [Method] Defined-strains-mixed fermentation was implemented with a consortium composed of Acetobacter xylinus, Zygosaccharomyces bailii, and Lactiplantibacillus plantarum. Single factor experiment and response surface methodology were employed to optimize the fermentation process. Physicochemical indices, functional components, and in vitro antioxidant activity were determined to evaluate the enhancement effects of defined-strains-mixed fermentation. [Result] The optimum fermentation process:fermentation with a strain volume ratio of 2∶1∶1 and an inoculum volume fraction of 6.8% at 31.1 ℃ for 32 h. The total phenol mass concentration of 325.68 μg/mL and total flavonoid mass concentration of 99.61 μg/mL, representing 1.14-fold and 1.42-fold increases over the pre-fermentation levels, respectively. The DPPH, ABTS⁺, and hydroxyl radical scavenging activities reached 2.21 μmol/mL, 10.08 μmol/mL, and 8.30 μmol/mL, respectively, all of which were significantly enhanced compared with the pre-fermentation levels, with the hydroxyl radical scavenging activity showing the greatest increase. [Conclusion] Defined-strains-mixed fermentation effectively elevates the mass concentrations of functional components and antioxidant capacity in sweet potato kombucha. This study provides data support for the value-added utilization of sweet potato resources and the development of novel kombucha products.

Abstract:[Objective] This study investigated the microbial community structure changes during the natural fermentation process of sour rice noodles, a traditional fermented food from Guiyang City, Guizhou Province and screened and isolated lactic acid bacterial strains with excellent acid-producing capacity and safety profiles, aiming to support the standardized production of sour rice noodles. [Method] The microbial community structure was analyzed through high-throughput sequencing technology. Strains were isolated, purified, and identified through morphological observation, physiological and biochemical assays, and 16S rRNA gene sequencing. The identified strains underwent acid production capacity measurement, hemolysis tests, and antibiotic susceptibility testing, on the basis of which the performance and safety of the strains were evaluated. [Result] High-throughput sequencing revealed that microbial diversity peaked during the soaking stage, with a stable community dominated by the genus g_Limosilactobacillus. Two lactic acid bacterial strains—Limosilactobacillus fermentum (L. fermentum) and Limosilactobacillus reuteri (L. reuteri)—were successfully identified from the samples. The two strains exhibited strong acid-producing capabilities, reducing the pH to 3.80 within 48 h in a rice substrate. Regarding safety, both strains demonstrated γ hemolysis in hemolysis tests, while antibiotic susceptibility testing indicated L. fermentum was relatively safe, and L. reuteri required a more comprehensive safety assessment. [Conclusion] In summary, L. fermentum selected in this study exhibits excellent fermentation and safety properties, being suitable for the standardized and industrial production of Guiyang sour rice noodles.

Abstract:[Objective] Carotenoid cleavage dioxygenases (CCDs) catalyze the degradation of β-carotene. However, due to the hydrophilic nature of CCDs, a system that provides biphasic enzymatic reactions is necessary to facilitate the enzymatic degradation of β-carotene. [Method] Hollow mesoporous silica-dihydromyricetin (HMS-DMY) composite nanoparticles were synthesized and used as the emulsifier to form the oil-in-water Pickering emulsion loaded with β-carotene and CCDs (HMS-DMY-E). The particle size and structure of HMS-DMY were characterized, and their influences on the particle size, microstructure, and rheology of HMS-DMY-E were investigated. Additionally, changes in the content of aroma compounds after enzymatic degradation were analyzed. [Result] HMS-DMY exhibited a particle size of 197.81 nm, a polydispersity index of 0.31, and a three-phase contact angle of 88.14°, showcasing favorable interfacial wettability for oil-water interface adsorption. HMS-DMY-E had a small particle size of 21.43 μm, which enhanced the contact area between β-carotene and CCDs, thereby promoting enzymatic degradation. The mass fractions of key aroma compounds such as β-ionone, β-cyclocitral, and dihydroactinidiolide were significantly increased after enzymatic degradation of HMS-DMY-E. [Conclusion] The Pickering emulsion prepared in this study serves as an efficient microreactor promoting the enzymatic degradation of β-carotene by CCDs and increasing the mass fractions of aroma compounds.

Abstract:[Objective] To address the issue of oxidation and degradation of chia seed oil (CSO) during its preservation and to meet the demand for its sustained release, the author utilized the high specific surface area and porosity of the metal-organic framework ZIF-8 to construct CSO-loaded ZIF-8 nanoparticles (CSO@ZIF-8) and developed an intelligent active film with the dual functions of extending the shelf life of fish meat and real-time monitoring of freshness. [Method] Chitosan (CS) was used as the film-forming matrix, blueberry anthocyanin (BA) as the pH indicator, and CSO@ZIF-8 as the functional active component. The film (CS/BA/CSO@ZIF-8) was prepared by the casting method. [Result] Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), and X-ray diffraction (XRD) analysis confirmed the successful loading of CSO onto ZIF-8. CSO@ZIF-8 and BA increased the antioxidant rate of the film to 86.46%. Compared with pure CS film, the CS/BA/CSO@ZIF-8 film exhibited superior mechanical properties. Additionally, the CS/BA/CSO@ZIF-8 film demonstrated good pH responsiveness, showing a color change from deep red to blue-purple to yellow-green as pH increased. It was then applied to the freshness detection of fish meat. The sensory analysis and measurements of pH, volatile basic nitrogen, and total colony count showed that the film could respond to the pH decrease caused by fish meat spoilage and trigger the release of active components to slow down the deterioration of fish meat, extending the shelf life to 6 d.Conclusion] The CS/BA/CSO@ZIF-8 film has a promising application prospect in monitoring the freshness of aquatic products.