6-α-glucosyltransferase has catalytic activities of exo-hydrolysis towards α-1,4-glucan and transglycosylation, and can produce the α-glucan which links α-1,6 glycosidic bonds on the nonreducing end through transglycosylation activity.Therefore, it can be used to produce cyclic alternating sugars and their branched derivatives, as well as cycloisomaltooligosaccharide, which can be used as new functional sugar.To expand the application of 6-α-glucosyltransferase in the food industry, the 6-α-glucosyltransferase from Bacillus globisporus N75 was expressed heterologously in the food safety strain Bacillus subtilis, and the expression level of recombinant protein increased by selecting the host strain and optimizing fermentation condition.These results indicated that the host WHS9 was more beneficial for the recombinant expression of 6-α-glucosyltransferase and the total soluble enzyme activity could achieve 2.11 U/mL at 20 ℃, including intracellular and extracellular.After adding 20 mmol/L trehalose, the total enzyme activity could reach 2.21 U/mL at 25 ℃ for 48 h.Then the fermentation period was optimized, and it was found that the highest enzyme activity could reach 3.14 U/mL at 36 h, which was 196 times higher than in WHS9 before optimization.This study firstly achieves recombinant expression of 6-α-glucosyltransferase in B.subtilis.

The production of 1,6-hexanediamine as the synthetic monomer of nylon 66 is mainly monopolized by foreign countries, and the traditional chemical synthesis of hexanediamine contains highly toxic cyanide, high technical barriers, long production process, how to use the biological method to make innovative breakthroughs in the context of carbon neutrality has become a challenge.However, up to now, no natural hexanediamine synthesis pathway has been reported.In this study, 6-aminohexanoic acid, a widely available substrate, was used to construct a synthetic pathway for hexanediamine through component-adapted assembly, and fermentation enhancement was combined to increase the yield of hexanediamine in engineered strains.Finally, excellent carboxylic acid reductase MAB CAR L342E, single transaminase HATA, and double transaminase combination PatA/VFTA were obtained through screening, and the initial hexanediamine yields of the engineered strains after combination could reach 3.01 mg/L (DAH4) and 8.50 mg/L (DAH37), respectively.On this basis, the fermentation conditions were optimized, and the yields of 1,6-hexanediamine reached 64.33 mg/L and 153.93 mg/L, which were 20.37 times and 17.11 times higher than those before optimization, respectively.This study has successfully constructed a pathway for the synthesis of hexanediamine by biological method, which provides technical support for the breakthrough of domestic chemical products.

To explore the protective effect of component from Poria cocos polysaccharide (PCP) on freeze-drying of compound lactic acid bacteria, purified component from Poria cocos polysaccharide was prepared successfully and its structure was characterized, studying its protective effect and mechanism on freeze-drying of compound lactic acid bacteria.Results showed that PCP-1 with total sugar content of (96.21±0.39)% was obtained after isolation and purification, and the weight average molecular weight of PCP-1 was 11 732 Da.PCP-1 is mainly composed of glucose and glucuronic acid, with the molar ratio of 0.989∶0.011.Moreover, there are hydroxyl groups and both α and β glycosidic bonds in PCP-1.Adding PCP-1 into the basic protective agent increased the freeze-dried survival rate of compound lactic acid bacteria by 11.29% when compared with PCP.The surface of lactic acid bacteria powder with PCP-1 was denser by observed with scanning electron microscope.Furthermore, the activities of Na⁺-K⁺-ATPase and lactate dehydrogenase of compound lactic acid bacteria were significantly enhanced by adding PCP-1 to the basic protective agent, which increased by 0.66 U/mg prot and 1.46 U/mg prot, respectively.The cell membrane integrity of the compound lactic acid bacteria added with PCP-1 was better maintained after double staining with propidium iodide and fluorescein diacetate.In conclusion, PCP-1 may reduce the freeze-drying damage of compound lactic acid bacteria by forming hydrogen bonds through the existence of hydroxyl groups, and improve the freeze-drying survival rate of compound lactic acid bacteria.

Since 15%-20% sucrose is usually added in a small baked bun, it is necessary to reduce the sucrose content and develop a non-sucrose small baked bun.Maltol, fructooligosaccharides, isomaltooligosaccharides, and galactooligosaccharides were used to replace sucrose to prepare sucrose-substituted small baked bun, and their effects on the quality of small baked bun were investigated, the reasons for the differences were discussed from the aspects of embryogenic properties and micro-state of starch and protein in small baked bun.Results showed that the effect of sucrose substitute on the color and taste of small baked buns was related to its properties and the influencing factors on taste are relatively complex.The hardness and specific volume of the small baked bun were 1 138.82 g and 1.81 mL/g, the hardness of fructooligosaccharides, isomaltooligosaccharides, and galactooligosaccharides group increased to 1 998.31, 1 956.79, and 1 426.21 g, respectively, and the specific volume decreased to 1.48, 1.49, and 1.29 mL/g.Further analysis showed that different sucrose substitutes had different abilities of hydrogen bond formation, which led to different distributions of water in embryogenesis, and then affected the rheological properties and formation difficulty of embryogenesis.The hardness of a small baked bun was positively correlated with the final viscosity of starch gelatinization and negatively correlated with the short-range ordering of starch, fructooligosaccharides, and isomaltooligosaccharides increased the final viscosity by 11.3% and 8.1%, respectively, and decreased the short-term order of starch by 17.3% and 12.1%.The specific volume of a small baked bun was negatively correlated with the gelatinization viscosity of starch and positively correlated with the thermodynamic termination temperature and the content of protein β-folding.The galactooligosaccharide group had higher gelatinization viscosity, lower termination temperature (72.90 ℃), and lower content of protein β-fold (38.36%), which resulted in slower gas expansion and earlier thermal solidification, the stability of the protein network was decreased and its specific volume was 1.29 mL/g.

Deep eutectic solvent (DES), emerging as a novel generation of green solvents, due to their simple preparation process, minimal toxicity, biodegradability, and other advantageous characteristics, can overcome the limitations of traditional organic solvents.Consequently, DES serve as excellent alternatives to conventional organic reagents.This paper presents a comprehensive review of the most recent research findings in the field of DES, including the composition categorization, preparation techniques, performance parameters, and its advancements in natural product extraction, food testing and analysis, as well as catalytic reaction media.This review summarizes the concerned issues currently associated with DES, while also prognosticating potential future applications.This work offers a valuable reference for further exploration of the biochemical characteristics of green solvent systems and their practical applications.

Cherry tomato, a kind of climacteric fruit, is easily affected by ethylene after harvest to accelerate its respiration, thereby promoting ripening and seriously shortening its shelf life.Therefore, developing novel packaging materials and technology for removing ethylene from the postharvest environment of cherry tomatoes shows important practical significance in reducing the economic losses caused by ethylene-induced ripening of postharvest fruits.This study used a calcination method to prepare a kind of photocatalyst of Fe-doped titanium dioxide nanoparticle (Fe-TiO₂) which might show photocatalytic activities under visible light irradiation.Compared with pure TiO₂ nanoparticles, the band gap width of Fe-TiO₂ decreased, the recombination rate of photogenerated electron-hole pairs decreased, and the ethylene degradation rate significantly increased under LED light irradiation.This study applied this technology of photocatalysis in the postharvest preservation of cherry tomatoes by detecting the variation of key indicators of fruit surface color to determine the postharvest ripening process and explored the effect of Fe-TiO₂ loaded by polyvinyl alcohol (Fe-TiO₂/PVA) and coated on fruit surface on cherry tomato postharvest ripening under LED light irradiation.The results showed that compared with the control group, the Fe-TiO₂/PVA coating treatment could effectively control the changes in fruit color from green to red, delaying about 4 days, and delaying the postharvest ripening process of the fruit.This study preliminarily demonstrated the application prospect of photocatalytic.

This paper systematically reviews the classification, metabolic characteristics, and advantages of sweeteners, with a particular focus on exploring the relationship between various sweeteners and human health.Sweeteners can be classified into two main categories based on their sources and chemical structures:natural and artificial, each exhibiting distinct metabolic characteristics.Studies indicate that excessive consumption of artificial sweeteners may be associated with risks of obesity, diabetes, and other diseases, while natural sweeteners such as sugar alcohols and steviol glycosides may possess beneficial effects such as modulating gut microbiota, anti-inflammatory, antioxidant, and hepatoprotective properties.This paper provides a reference for subsequent sweetener processing directions, particularly serving as a theoretical basis for research on the relationship between sweeteners and human health.

Inhibiting the activity of acetylcholinesterase (AChE) is beneficial to the elevation of acetylcholine levels thereby alleviating cognitive impairment and memory decline in the elderly.In this study, the active ingredients in soymilk and fermented soymilk were extracted by ethanol solvent, and the AChE inhibitory activity of the two extracts was measured.Then, ultra-performance liquid chromatography quadrupole time of flight mass spectrometry was used to identify the extracts in the chemical components.The differential components with significant content changes before and after fermentation were screened by SIMCA software.After that, molecular docking technology was used to screen the active ingredients among the differential components, and their binding ability and interaction forces with AChE were explored.Results showed that lactic acid bacteria fermentation can significantly (P<0.05) improve the AChE inhibitory activity of soymilk, and its IC₅₀ value decreased from 3.24 mg/mL to 2.55 mg/mL.A total of 84 components were identified from soymilk and fermented soymilk extracts, of which 19 components had significant content changes before and after fermentation.The molecular docking results showed that 13 components were able to tightly bind with AChE.These active ingredients mainly interact with amino acid residues in AChE active sites through hydrogen bonding and hydrophobic interactions, thereby inhibiting AChE activity.

Triacetic acid lactone (TAL) is a promising platform polyketide with broad applications, especially it can be used as a precursor for the synthesis of various organic compounds.This study characterized the repeating sequences on the yeast genome to integrate the TAL biosynthesis pathway into these sites for enhanced gene expression and TAL production by Saccharomyces cerevisiae.Firstly, this study used the green fluorescent protein as the reporter to characterize multi-copy integration by the Delta1 site.It showed that truncating the promoter of a selection marker gene (for geneticin or hygromycin B) or increasing the antibiotic concentration, were effective in improving the integration efficiency and copy numbers.The highest copy number of multi-copy integration was obtained when truncating the antibiotic gene promoter to 15 bp, and using an antibiotic at 160 μg/mL.The optimization system was subsequently used to characterize the second multi-copy integration site, Delta2, with similar results.Then, the optimized multi-copy integration system was applied to introduce the TAL biosynthesis pathway into S.cerevisiae.The highest pathway copies using Delta1 and Delta2 sequences were 10 and 7, respectively, with Delta1 slightly better than Delta2.After 48 h fermentation in YTD medium, TAL titers of the Delta1-integration strain and the Delta2-integration strain were 1.50 mmol/L and 1.17 mmol/L, respectively, 460% and 337% higher than the single-copy integration strain.This study demonstrates that the multi-copy integration system is an efficient approach to introducing heterologous pathways into S.cerevisiae to improve biocatalytic efficiency.

Compounding different amylose/amylopectin starch and non-thermal processing treatments are effective means to change the physicochemical properties of starch.In order to explore the effect of high hydrostatic pressure treatment on the compounding system of high amylose corn starch and waxy corn starch, the physicochemical properties and structural changes of different proportions of the compounding starch before and after high hydrostatic pressure (600 MPa/30 min) treatment were investigated.The results showed that the solubility, viscosity, and pseudoplasticity of the compounding starch increased with the increase of the proportion of waxy maize starch;the storage modulus and loss modulus of the compounding starch increased after high hydrostatic pressure treatment;and the pasting temperatures of the systems with high amylose∶Waxy starch of 0∶5 and 2∶3 decreased by 15.82 ℃ and 17.62 ℃ after high hydrostatic pressure treatment, respectively;the relative crystallinity and short-range degree of compounding starch were reduced after high hydrostatic pressure treatment;among which the waxy corn starch granules were seriously damaged, but the high amylose corn starch granules were relatively complete;in vitro digestion results demonstrated that high hydrostatic pressure treatment reduced the resistant starch content and significantly elevated the slowly digestible starch content.Therefore, compounding corn starch with different amylose contents and treating them with high hydrostatic pressure treatment might be utilized as a method of physical modification of starch, which could be of high value for its application in the field of starch-based gels.

Curcumin is a natural polyphenolic substance extracted from ginger plant.Adding curcumin into foods can make them have unique color, produce special flavor, and provide people with certain health care functions.Moreover, curcumin has significant medicinal value, such as improving human immunity and accelerating body metabolism.Specifically, curcumin has many physiological functions, for example, it can act as an anti-inflammation agent, antibacterial agent, antioxidant, lipid-lowering agent, and gallbladder enhancer.Curcumin has been widely used in the fields of food, pharmacy, and animal production, but its poor water solubility and stability limited its application.In this paper, the physicochemical properties, extraction, functional properties, application, and solubilization technology of curcumin were reviewed, providing a reference for further research on curcumin.

Enzymes of Daqu are one of the key factors affecting the quality of Daqu and Baijiu.Understanding the enzymes is of great significance for optimizing the Daqu-making technology and revealing the mechanism of Baijiu fermentation.In this study, advanced technologies for investigating the enzymes of Daqu were introduced, and their advantages and disadvantages were discussed.Additionally, known functional enzymes in typical Daqu were summarized.High-throughput sequencing and metaproteomics could be used to analyze the composition and function of enzymes in Daqu from the perspective of genome, transcriptome, and proteome.Currently, the key functional enzymes involved in the pathways of saccharification and ethanol fermentation in low-temperature Daqu, medium-temperature Daqu, and high-temperature Daqu have been identified by using the above technologies.However, because the above technologies have difficulties in detecting enzymes with lower content in Daqu, the functional enzymes involved in the pathways of flavor compound metabolism in Daqu cannot be fully identified at present.There is an urgent need to upgrade relevant technologies to promote the research on the enzymes in Daqu.

The effects of Clavispora lusitaniae CP-1 (CP-1) on total polyphenols (TPs), total flavonoids (TFs), main flavonoids and antioxidant activities of ethanol extracts from Citri Reticulatae Pericarpium (CRP) were studied.The contents of the main flavonoids were determined by HPLC.The antioxidant activity was measured by DPPH assay, ABTS assay, FRAP assay and ORAC assay.The transformation conditions of CP-1 on hesperidin were optimized by orthogonal design.The results showed that the contents of TPs and TFs increased by 42.22% and 9.46%, respectively, after CP-1 transformation for 24 h.With the extension of transformation time, hesperitin content increased 7.52 times.The contents of naringenin and hesperitin-7-O-glucoside reached the maximum value at 8 h, and then gradually decreased.The contents of narirutin, hesperidin, nobiletin and tangeretin were decreased by 85.10%, 88.86%, 72.13%, and 81.82%, respectively.α-L-rhamnosidase and β-D-glucosidase involved in transformation mainly exist in intracellular enzymes and cell fragments.CP-1 also enhanced the antioxidant activity of ethanol extract of CRP, increasing DPPH value, ABTS value and FRAP value by 20.66%, 9.73%, and 9.84% respectively, while decreasing ORAC value by 3.30%.The transformation condition of CP-1 on hesperidin was optimized.The optimal conditions were as follows:pH 6.5, yeast concentration 4.9×10⁹ CFU/mL and hesperidin concentration 2.5 mmol/L.The results of this study provide a theoretical basis for studying the mechanism of microbial transformation of citrus flavonoids, and have important significance for high-value utilization of citrus peel residues by-products.

Squid belongs to the cephalopod class of mollusks, with short survival time, fast reproduction speed, comprehensive nutrition, high protein content, low-fat content, and low-calorie content.Squid skin accounts for 8%-13% of squid processing waste, and full utilization of squid skin can prevent resource waste.This article reviewed the nutritional components, peeling methods, extraction methods of collagen and gelatin from squid skin, as well as the preparation methods of squid skin collagen peptides with antioxidant activity, anti-hypertension, anti-skin aging, anti-tumor activity, and anti-freezing activity.The application of squid skin collagen products in industries such as food, medicine, cosmetics, and cosmeceuticals was also introduced.This article provided a systematic introduction to the research progress in the processing and utilization of squid skin, aiming to provide a theoretical basis for the deep processing of squid skin and promote the sustainable and healthy development of China’s aquatic product processing industry.In the future, the research should focus on optimizing the extraction process of squid skin collagen, improving the targeting of its target peptide screening, and conducting active clinical validation studies, to provide reference for the development and high-value utilization of squid skin.

Gamma-aminobutyric acid (GABA) is the main inhibitory neurotransmitter in the human central nervous system.GABA has many effects such as relieving anxiety, insomnia, and anti-aging, etc.Therefore, appropriately intaking of GABA from diet is essential for human health, and grains are one of those food sources.Germinated grains are green, flavorful, natural health foods and they are rich in GABA.During the process of grain germinating, GABA is metabolized through the GABA shunt and polyamine metabolic pathway.This paper described these metabolic pathways of GABA synthesis.Enzyme activities, gene expression levels and external factors have different impacts on the accumulation of GABA.GABA is rapidly accumulated during grain responses to abiotic stress.The different factors which affecting the GABA accumulation metabolism were reviewed.We summarized the recent research on GABA accumulation and mechanism with the goal of providing a review of GABA in grains.

Compared to model microorganisms, the food-safety grade industrial bacteria Bacillus licheniformis has a serious lack of standardized genetic tools for synthetic biology, such as plasmid vectors, which limits its use in research and applications.Using a technique we developed for assessing plasmid characteristics in Bacillus licheniformis, we were able to identify and obtain extremely effective replication primordia in this work.A variety of artificial replication origins were logically created based on the additional analysis of the molecular process by which the stem-loop structure in the replication origin influences plasmid copy number and stability.According to the findings, the replication origin ORIT5 from B.subtilis had a copy number that was 2.15 times larger and more stable than the endogenous replication origin pHY300 (up to 40.2).With the addition of a TCCGCC stem-loop at the 3′ end, pT1, an artificial replication origin, enhanced stability by 36% and raised copy number to 62.2.The maximal enzyme activity of the recombinant bacterial fermentation bearing the pT1 replication origin was 8 726.7 U/mL, which was 43.9% greater than that of the starting strain, using malt oligosaccharide-based alginate synthase as the reporter protein.The creation and use of the artificial replication origin set the stage for Bacillus licheniformis′s expression system to be enhanced and perfected.

‘Cuixiang’ kiwifruit are usually hard when purchased and need to be stored to soften before they can be eaten.However, kiwifruit are respiratory leaps that are prone to concentrated ripening, and the uncontrollable evolution of kiwifruit fruit quality during home storage can lead to a poor consumer experience and a reduced desire to buy.In this paper, the evolution of fruit quality of ‘Cuixiang’ kiwifruit under home storage conditions was systematically analyzed based on the dimensions of physicochemical characteristics, organoleptic quality, and aroma characteristics.In terms of physicochemical characteristics, titratable acid content and hardness of kiwifruit decreased significantly during home storage, while the content of total soluble solids, sugar-acid ratio, and weight loss tended to increase significantly.Based on the correlation of the above indexes, hardness was chosen to establish a zero-level kinetic shelf-life prediction model, and the model had good accuracy and reliability.Meanwhile, the artificial sensory evaluation showed that, except for the appearance score, which continued to decrease during the storage period, the scores of other sensory indexes, such as color, aroma, taste, texture, etc., increased significantly and peaked on the 11th day.Therefore, the total artificial sensory scores of ‘Cuixiang’ kiwifruit were the highest on the 11th day of home storage, which was the most suitable for consumption at this time.Gas chromatography-mass spectrometry was used to evaluate the aroma profile of kiwifruit, and a total of 513 volatile organic compounds were detected, with ester concentrations accounting for the highest percentage of kiwifruit samples at different stages of home storage, and terpenes showing the highest percentage of species.On the 1st day and the 7th day, the volatiles were more abundant and the aroma was more complex, with the highest content of aldehydes and a prominent herbaceous note.On the 11th day, the proportion of esters in the total volatiles was significantly higher than that on the 1st day and the 7th day, and the fruity and sweet flavors were more intense.

The raw materials and degree of fermentation affect the growth and metabolism of fermented Pu-erh tea microbiota, which ultimately affects the quality of fermentation.This study used 16S rRNA and ITS amplicon sequencing to study the effect of the raw materials and degree of fermentation on the fermented Pu-erh tea's microbiota differences and quality.Results showed that the abundance and diversity of the prokaryotic microbiota of high-fermented Pu-erh tea were significantly higher, but the abundance of eukaryotic flora decreased significantly.Compared to light-fermented teas, the high degree of fermentation was more conducive to increasing the content of soluble polysaccharides, lignin, total flavonoids, proteins, and theabrownin in Pu-erh tea.The fermentation of tea stems significantly increased Pseudomonas (86.78%) abundance and decreased protein content.Adding honey significantly increased Aspergillus (87.47%) abundance and increased the content of theabrownin.Fermentation of yellow tea-leaf comprehensively increased the abundance of Aspergillus (31.90%), Thermomyces (41.91%), Rhizomucor (20.09%), Pseudomonas (40.46%), and Bacillus (21.44%), and increased the content of soluble polysaccharides.The predictions of PICRUSt2 function revealed that the degree of fermentation had a greater effect on the microbiota of fermented Pu-erh tea than the fermented raw material.Redundancy analysis revealed that free amino acids, lignin, cellulose, and theabrownin were significantly associated with eukaryotic microbiota, while proteins and soluble polysaccharides were significantly associated with prokaryotic microbiota.This study provides a theoretical basis for the strain improvement of the fermentation process of Pu-erh tea.

In this study, the mycelia of Ganoderma sessile were used to prepare mycelium base composites (MBCs), C-MBCs (corn stalks), and H-MBCs (hemp stalks), respectively.To obtain more active mycelium seeds, the liquid cultivation conditions were optimized.The study included the effects of carbon sources, nitrogen sources, initial pH, temperature, G.sessile content, liquid volume, and rotating speed on the mycelial biomass of fermented products.Both C-MBCs and H-MBCs were measured for scanning electron microscope, compressive strength, and thermogravimetric characteristics.Results showed that the best mycelium cultivation medium was 25 g/L corn flour, 14 g/L soybean powder, 3 g/L KH₂PO₄, and 3 g/L 7H₂O·MgSO₄.The optimized fermentation conditions were fermentation temperature at 28 ℃, initial pH 5.5, G.sessile content with 5%, liquid volume 150 mL/500 mL flask, and rotating speed 180 r/min.Under the optimized conditions, the mycelial biomass in the cultural broth was 18.73 g/L, which increased by 34%, compared with those before optimization.The compressive strength and thermogravimetric characteristics of C-MBCs and H-MBCs were both better than expanded polystyrene.It’s concluded that this result will provide a reference for the application of MBCs instead of foam plastics in cushioning packaging.

Astaxanthin is widely used in industries such as cosmetics, feed additives, and healthcare due to its antioxidant, coloring, and health-promoting properties.The traditional production process of astaxanthin mainly includes natural extraction and chemical synthesis.However, they cannot meet the growing market demand and consumer demand for natural products.With the rapid development of synthetic biology, the synthesis of astaxanthin by microbial fermentation is a more efficient way.Many naturally occurring sources of astaxanthin, such as Xanthophyllomyces dendrorhous and genetically engineered yeasts such as Saccharomyces cerevisiae, Yarrowia lipolyticus, and Kluyveromyces marxianus, have been isolated and constructed.To improve the efficiency of astaxanthin production through industrial yeast fermentation, researchers used a variety of strategies such as mutagenesis, genetic modification, and fermentation regulation, and explored ways to synthesize astaxanthin using different cheap substrates.Therefore, this study systematically reviews the research progress of yeast astaxanthin synthesis, analyzes the main factors affecting astaxanthin synthesis from the metabolic pathway of yeast and the current status of astaxanthin synthesis using different raw materials, and proposes methods and strategies for yeast to produce astaxanthin.