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.

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.

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.

Recombinant collagen is a biopolymer with broad potential applications in various fields, such as biomedicine and tissue engineering.The triple-helix structure of collagen imparts unique biological functions and biocompatibilit but also increases the complexity of its expression in microbial systems.In this study, bacterial collagen V-B was used as a model protein to promote the expression of recombinant collagen in Corynebacterium glutamicum through optimization of expression elements.Firstly, the most efficient promoter tac-R0 was obtained through promoter screening and fermentation duration optimization.Subsequently, the RBS calculator was used to design a mutation library for ribosome binding sites (RBS) and aligned spacing (AS).The RBS and AS with the highest strength were identified, which increased the yield of V-B to 514 mg/L.Furthermore, through the tandem combination of multi-gene expression cassettes, the final yield of V-B increased by 8.4-fold compared to the initial level, reaching 697 mg/L.This study lays a foundation for the industrial production of recombinant collagen.

‘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.

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.

Diacetyl is one of the most important substances in dairy products and contributes to buttery flavor in cheese.Based on the biosynthesis pathway of diacetyl, 23 strains of lactic acid bacteria were screened according to the ability to produce diacetyl, activities of acetoin reductase, α-acetolactate decarboxylase, and diacetyl reductase for adjunct culture, the growth ability in ripening environment of cheddar cheese, and autolysis degree.The impact of the selected adjunct culture on the properties of cheddar cheese was evaluated with a rapid ripening model.The ripening experimental results showed that the addition of adjunct cultures did not result in significant difference in the physical and chemical indicators, proteolysis, and texture of cheddar cheese except the flavor profile.Compared to the other groups, diacetyl content and buttery flavor was higher in the cheddar cheese prepared with CCFM 601, and the decline of diacetyl was slower during ripening.Therefore, the addition of adjunct cultures in cheddar cheese with high production ability of diacetyl could enhance the milky flavor of cheddar cheese during ripening.

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.

To improve the texture and edible quality of bamboo shoots in pouches with different fruit pieces, the effects of ultra-high pressure (UHP) and thermal processing (TP) on the hardness, viscosity, and pH of soup, relative conductivity, microstructure, cellulose and lignin content, pectin content, and esterification degree of different fruit pieces, such as half-striped, filamentous, sliced and diced samples were investigated.Results showed that the hardness of half-striped, filamentous, sliced, and diced fruit pieces decreased by 3.2%, 8.6%, 14.7%, 23.5% and 37.4%, 46.2%, 52.4%, 64.8% after UHP and TP, respectively.The viscosity and pH of canned juice after processing increased with the decrease of the volume of fruit pieces, and the viscosity of TP juice was much higher than that of UHP.The microstructure showed that the cell arrangement was more compact after UHP, while the cell gap increased after TP, and the relative conductivity of TP was much higher than that of UHP, with the smaller the volume of the fruit pieces, the more serious the cell breakage and the larger the relative conductivity after processing.Compared with TP, UHP bamboo shoots had higher chelator soluble pectin (CSP) and sodium carbonate soluble pectin (NSP) and lower water soluble pectin (WSP).The smaller the size of the fruit pieces, the lower the CSP and NSP, and the higher the WSP.Cellulose and lignin contents of different fruit pieces did not change significantly after UHP/TP, and the esterification degree of UHP pectin was significantly lower than that of TP, and there was no significant difference in the esterification degree between different fruit pieces.In conclusion, the texture retention effect of bamboo shoots from different fruit pieces after processing was in the order of half-stripes > filaments > slices >dices, and UHP could better retain the texture of bamboo shoots compared with TP.

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 recent years, global warming has led to an increase in the sugar content of grapes, which has led to a gradual increase of ethanol content in wine.The high ethanol content will affect the flavor characteristics of wine and human health.Therefore, how to effectively reduce the ethanol content in wine has attracted more and more attention.It is of great significance to deeply study the regulation mechanism of ethanol metabolism in Saccharomyces cerevisiae, and to select low-yield ethanol S.cerevisiae, in order to solve the wine quality problems caused by high alcohol content in wine.In order to provide a reference for obtaining excellent low-yielding ethanol strains and achieving precise regulation of ethanol content in wine.The metabolic pathways and key regulatory genes of ethanol in S.cerevisiae were reviewed firstly.Furthermore, the molecular mechanism of S.cerevisiae in regulating ethanol production is analyzed.Finally, the common methods in the selection and breeding of low-yielding ethanol strains are summarized.

The bioreactor serves as the fundamental equipment in the biomedicine and biotechnology industry, with the global market witnessing continuous growth year after year.It is poised to become a pivotal driver of expansion within the realm of equipment manufacturing.With the rapid advancements in synthetic biology and artificial intelligence technology, high-throughput and miniaturized bioreactors have been implemented for process development and optimization, while large-scale bioreactors are evolving towards low energy consumption and intelligent operation.The intricate flow field structure within a bioreactor poses a significant challenge to scaling up biological processes, necessitating comprehensive research on factors such as mixing, mass transfer, shear stress, among others.To enhance the, techniques like artificial intelligence and machine learning are indispensable for data acquisition and optimization purposes.In the future, highly integrated intelligent bioreactors expertise from various domains including biotechnology, information technology, and control technology will find extensive applications across multiple fields.

The alluring aroma of jasmine is adored by people worldwide.Benzyl acetate, a key component of the scent of jasmine, is a valuable aromatic ester compound and extensively used as flavor and fragrance in food, cosmetics, and pharmaceutical industries.However, its current production heavily relies on chemical synthesis.In this study, a de novo synthesis pathway of benzyl acetate was established in Escherichia coli strains, and benzyl acetate was successfully synthesized by microbial fermentation.Firstly, to construct the synthesis pathway of benzyl acetate, nine functional enzymes were co-expressed in BL21 (DE3) using a modular strategy.The resulting strain BZ04 produced (85.55±10.85) mg/L benzyl acetate by two-phase in situ extractive fermentation.Subsequently, the production of benzyl acetate was enhanced through the optimal screening of key acyltransferase derived from various sources and optimization of various flask culture conditions including the screen of carbon sources, the addition of solubilizer, and the increase of oxygen supply.Under optimal fermentation conditions, the final strain of BZ05 produced (592.22±36.95) mg/L benzyl acetate from glycerol in shake flasks, which was seven times compared to original production of benzyl acetate.This study provides an eco-friendly and sustainable approach for benzyl acetate production.

Research in the realm of type 2 diabetes mellitus (T2DM) has recently highlighted highland barley as a promising dietary intervention due to its low glycemic index and high fiber content.This study investigated the effects of highland barley juice and its lactic acid-fermented derivative on glucose and lipid metabolism, as well as their influence on gut microbiota in db/db mice.Over a four-week period, 25 db/db mice received these barley-based interventions, with subsequent assessments of body weight, glycemic biomarkers, and microbial diversity.The findings revealed distinct mechanisms by which highland barley juice and its lactic acid-fermented counterpart modulate blood glucose and lipid profiles.The fermented beverage, in particular, demonstrated significant glycemic control, alongside improvements in lipid metabolism indicated by reduced triglyceride and total cholesterol levels.Additionally, it was associated with an increase in beneficial gut microbial populations.In essence, this study elucidated the differential impact of highland barley juice and its fermented version on metabolic parameters in T2DM, suggesting a beneficial role in disease management.The results advocated for further exploration into the use of highland barley-based products as a dietary strategy for improving T2DM outcomes.This work not only contributes to the understanding of functional foods in glycemic regulation but also underscores the potential synergistic relationship between diet, metabolic health, and gut microbiota composition.

Wolfberries in China are mainly distributed in the northwest region, divided into red, black, and yellow wolfberry.Wolfberry is a medicinal food homologous food rich in nutrients and active ingredients, therefore, wolfberry shows some functional properties, such as lowering blood sugar, lowering blood lipids, resisting oxidation, resisting ageing, regulating immunity, relieving asthenopia, resisting tumors, protecting the nervous system, and regulating intestinal flora, etc.Due to the difficulty in preserving and transporting fresh wolfberries, they are often processed into beverage products, dried wolfberries, and other foods.At present, 80% of wolfberries on the market are still sold as dried wolfberries, and beverage products have become the main products of the new wolfberry consumer market, and other foods are mostly in the research and development stage.This article reviewed the variety classification, nutritional characteristics and mechanism of action, and the development status of food products of wolfberry, which would provide a basis for further research on the nutritional components and active ingredients of wolfberry and the deep processing of food and look forward to the future research and development of wolfberry industry to provide a theoretical basis for the research and application of wolfberry functional characteristics and food development and application.

Rice bran peptides were extracted by high-pressure homogenization-assisted enzymatic extraction technology from three varieties of indica rice bran and three varieties of japonica rice bran.The peptides in the enzymatic hydrolysate were separated, purified and identified to investigate their anti-aging mechanism.Results showed that the optimal extraction conditions for rice bran peptides based on peptide content and reducing power when the homogenization pressure was 60 MPa, the material-to-liquid ratio was 1∶15 (g∶mL), enzyme dosage was 3 200 U/g, enzymolysis time was 2 h, pH was 10, and enzymolysis temperature was 55 ℃.The protein hydrolysate with the highest antioxidant activity has been identified.Totally sixty peptides with good activity were obtained through ultrafiltration, Sephadex G-25 separation and purification, and LC-MS/MS analysis.The results of molecular docking showed that the peptide YGGGY had the lowest binding free energy, and it interacts with the active site of the CD38 protein (NAD⁺ degrading enzyme) through hydrogen bonding, van der Waals forces, salt bridges, etc.This suggested that it had the potential function of inhibiting the activity of the NAD⁺ degrading enzyme so that the organism could provide sufficient NAD⁺ content against oxidative stress and slow down aging.It provides a scientific basis for analyzing and interpreting the antioxidant mechanism of rice bran peptide and for the development of whole grain products.

The combination of meal and wine has always been one of people’s pursuits for a better life.The academic community’s interest in the study of meal and wine pairing is rapidly growing, but there is still a lack of scientific empirical evidence.For the first time, this study adopted a within-subjects design and used correlation analysis, ANOVA and other methods to explore consumer preferences for taste and Baijiu pairings.Results showed that four typical Baijiu (elegant-flavor Baijiu, chi-flavor Baijiu, strong-flavor Baijiu, and sauce-flavor Baijiu) could significantly weaken sweet and sour taste.In addition, strong-flavor Baijiu could weaken bitter taste, while sauce-flavor Baijiu could weaken umami taste.Consumer preferences for different types of Baijiu and taste pairings were significantly different, and preferences were significantly related to taste intensity changes, purchase intention, and recommendation.Four types of Baijiu had the highest preference for pairing with a sour taste, but there were differences in other tastes suitable for different types of Baijiu.In addition to the sour taste, the combinations of chi-flavor Baijiu and elegant-flavor Baijiu with sweet and salty taste were more satisfactory, while strong-flavor Baijiu and sauce-flavor Baijiu were more suitable for sweet and umami taste.In this study, a taste solution was used to induce a basic taste experience and to explore the matching preference between it and different types of Baijiu, which laid the foundation for further research on meal and wine pairing.

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.