Objective To explore the effects of glnA gene on the production of curdlan by Agrobacterium. Methods A glnA gene knockout strain ΔglnA was constructed in this paper. The growth and metabolism of ΔglnA strain and the changes in yield, gel properties and infrared structure of the obtained gum were analyzed, and the expression of genes related to the synthesis of curdlan was explored by quantitative real-time polymerase chain reaction. Results The amino nitrogen consumption of the ΔglnA strain during fermentation was consistent with that of CGMCC11546. In terms of sucrose consumption, there was no significant difference before 12 h, but there was a significant difference between the ΔglnA strain and CGMCC11546 after 15 h, and sucrose consumption was significantly reduced compared to CGMCC11546. The ΔglnA strain could produce approximately 4 g/L of natural gum, which was 60% lower than CGMCC11546. Conclusion The glnA gene does not affect bacterial growth or the structure of collagen, but it can reduce the synthesis of collagen. This study provides insights into the role of glnA in curdlan production and lays a molecular biological foundation for further efforts to enhance curdlan yield.

Objective To predict and control the fermentation process of Agrobacterium sp. A02 strain to produce curdlan, establish a time-varying model to simulate bacterial growth and obtain the kinetic changes of curdlan production and sucrose consumption. Methods The viable bacteria count, sucrose content and curdlan content during the batch fermentation process of Agrobacterium sp. A02 were measured, and the experimental values were fitted using Logistic equation, Luedeking-Piret equation and Luedeking-Piret-Like equation, respectively. Results The fitting results indicated that the 3 kinds of models were applicable to the growth kinetics of bacterial cells, the generation kinetics of pectin, and the consumption kinetics of sucrose. The R² were above 0.99, and the significance level was extremely significant. The errors between the fitted and experimental values were less than 10%, indicating a good fit. Conclusion The established bacterial growth kinetics model, sucrose consumption kinetics model and curdlan production kinetics model can predict and describe the dynamic metabolic changes of Agrobacterium sp. A02 during the fermentation process, providing theoretical support for describing the fermentation kinetics characteristics and industrial production of curdlan.

Objective To explore the differences in volatile aromatic substances of Marselan wine from the eastern foot of Helan Mountain production area during the aging periods of 0, 3 and 6 months. Methods Comprehensive two-dimensional gas chromatography-time of flight mass spectrometer (GC×GC-TOF MS) was used to detect the volatile aromatic substances in the wine. Key differential volatile substances were screened according to the variable importance in projection (VIP) value and orthogonal partial least squares-discriminant analysis (OPLS-DA). Results The types of volatile aromatic substances during the wine aging period mainly included alcohols, esters, acids, phenols, etc. A total of 1286 kinds of substances were detected in the 3 aging periods. The relatively high contents of volatile aromatic substances were alcohols, esters and hydrocarbons. With the increase of the aging period, the content of esters increased from 16.9% to 27.9%, and the content of hydrocarbons increased from 13.6% to 21.5%, both showing a significant upward trend. However, the content of alcohols decreased from 53.8% to 30.3%, showing a downward trend. Taking VIP≥1.22 and P<0.01 as the indicators, a total of 21 kinds of volatile aromatic substances with important contributions to the wine in different aging periods were determined, which were 2,6,6-trimethylcyclohexadiene-1-methanol, 2-propyl-1-heptanol, heptanal, 4-tert-butylbenzyl alcohol, (S)-1-phenylethanol, diethyl methylsuccinate, isoamyl propionate, acetal, methoxyacetaldehyde, 3-chloro-1-butene, 1,8-cyclopentadeca- 1,3-diyne, β-ionone, linalool, linalyl formate, 2-furanmethanol, rose oxide, hexahydro-1,3,5-trinitro-1,3,5-triazine, 4-ethyl-5- hydroxy-3,5-dimethylfuran-2(5H)-one, 2(5H)-furanone,4,5,5-trimethyl-3-(3-methyl-2-methylidenebutyl), N-methylhexylamine, and dimethyl disulfide. Conclusion This study, by analyzing the volatile aromatic substances in Marselan wine during different aging periods, provides a theoretical basis for the control of the flavor quality during the wineaging period.

Germinated brown rice, as a functional food ingredient, is widely used in food processing. Germinated brown rice is rich in nutrients, including γ-aminobutyric acid, γ-glutamine, dietary fiber, polysaccharides, glutathione, inositol, and octacosanol, among other bioactive substances. Germinated brown rice has a variety of physiological effects, such as anti-oxidation, lowering blood lipids, lowering blood pressure, preventing diabetes, preventing and treating cancer; it also has physiological functions such as improving memory, preventing senile dementia, sobering up, regulating emotions, improving skin, and enhancing gut microbiota. The staple food products processed with germinated brown rice as raw materials include Mantou, rice, noodles, bread, biscuits, etc. They can also be processed into germinated brown rice tea, fermented drinks, brown rice wine and other drinks; it can also be processed into germinated brown rice noodles, brown rice porridge, brown rice cake, brown rice vinegar and other foods. By improving the production technology of germinated brown rice, developing distinctive germinated brown rice food, the industrialization process can be accelerated. This article reviewed the nutritional characteristics, bioactive substances, physiological functions, and application research progress of germinated brown rice in the food industry, in order to provide reference for the promotion and application of germinated brown rice.

Cichorium intybus L. is a plant with high medicinal value and wide range of uses. The roots, stems, leaves and seeds of Cichorium intybus L. are highly nutritious and have a wide range of health benefits, such as regulating blood sugar, weight loss, combating malaria and preventing cardiovascular disease. Cichorium intybus L. root is rich in inulin, a polysaccharide composed mainly of fructose units, but also contains a small amount of monosaccharides, as well as chlorogenic acid and sesquiterpene lactones and other biologically active compounds, which have the function of regulating and improving gastrointestinal function, balancing blood glucose metabolism, improving lipid metabolism, lowering blood pressure, strengthening the immune system, antioxidant, anti-fatigue effects and other functions. Cichorium intybus L. can be processed into a variety of products, such as root tea, bread, functional foods, sugar substitutes and so on. This paper summarized the nutritional composition, functional characteristics, and research progress of Cichorium intybus L. in the food industry, and proposed solutions based on the problems existing in the application of Cichorium intybus L. in the food industry, which can provide reference for the development of the Cichorium intybus L. industry.

Objective To investigate the effects of light and air on the storage quality and volatile flavor compounds of rice bran. Methods Fresh and high temperature and pressure steam stabilized rice bran were used as raw materials to investigate the effects of light and air on the changes of acid value, peroxide value, γ-oryzanol content, chromaticity and other physicochemical indexes as well as volatile flavor compounds during storage. Results During the storage process, light and air exerted insignificant influences on the acid value and γ-oryzanol content of stabilized rice bran, and had limited effects on the chromaticity indices L^*, a^* and b^* values. However, they had a significant impact on the peroxide value. For the stabilized rice bran, the peroxide value could increase by up to 25 times in the presence of light and air. As the storage time extended, the types of volatile flavor substances in rice bran samples kept increasing. The treatments of avoiding light and vacuum could effectively prevent the generation of oxidation products such as aldehydes, ketones, and alcohols. In the presence of light and air, the concentrations of aldehydes and ketones in the stabilized rice bran increased by 6 times and 26 times. Conclusion The acid value of rice bran stabilized using high temperature and high pressure steam exhibits minimal changes when exposed to light and air during storage. However, the peroxide value and its oxidation products increases substantially, this indicates that avoiding light and vacuum treatment is the key to extending the shelf life of stabilized rice bran, providing a theoretical basis for its storage and industrial application.

Objective To explore the mixing ratio of different oil seeds in microwave-assisted blended cold pressing process, and develop polyunsaturated fatty acid balanced oil that meets the recommended dietary intake ratio. Methods The safflower seed and flaxseed were used as raw materials. The process parameters were optimized by single factor experiment (microwave treatment time, pressing temperature and moisture content of oil seed) and Box-Behnken response surface experiment. The oxidation characteristics of blended cold pressed oil were compared and analyzed. Results The mass ratio method determined that the blended mass ratio range was 1.8-2.4 (safflower seed:flaxseed, W_s:W_f). This method was simple and the results did not need to be verified, but it had the disadvantages of large demand for raw materials and low accuracy of boundary value. The mixing ratio range determined and verified by the fatty acid ratio method was 1.66-2.59 (W_s:W_f). This method had less raw material demand and high accuracy near the boundary value. However, due to the interaction of oil seeds, verification experiments needed to be carried out. Response surface methodology was used to optimize the process parameters of microwave-assisted blended cold pressing. The optimal extraction conditions were as follows: Microwave (800 W) treatment time 1.5 min, cold pressing temperature 64 °C, oil seed moisture content 6.7%, oil extraction rate 19.83%±0.21 %, which was 17.2% higher than that before optimization. The basic physical and chemical indexes of blended cold-pressed oil and traditional cold-pressed blend oil were compared and analyzed. The oil oxidation degree was lower under the condition of microwave-assisted blended cold-pressed process. Conclusion Microwave-assisted blended cold pressing oil has lower primary and secondary oxidation product indexes than traditional cold-pressed blended oil. The results can provide a theoretical basis for the preparation of polyunsaturated fatty acid equilibrium oil and the application of microwave-assisted blended cold pressing process in the field of grain and oil processing.

Objective To investigate the endogeneity and distribution characteristics of vanillin in different growth stages of Oryza sativa. Methods Longjing 46, Yanfeng, and Liaoxing were selected as the experimental materials. Samples were taken at different parts of Oryza sativa during its whole growth period. The vanillin content was determined by high performance liquid chromatography-tandem mass spectrometry method. Results Vanillin was present in Oryza sativa plants as early as the seedling stage. Its content in roots and leaves was 1100-1450 μg/kg and 596-972 μg/kg, respectively. During the growth process of Oryza sativa, the vanillin content in roots reached its peak at heading stage, with a content of 6560-8900 μg/kg. Subsequently, from full-heading stage to maturity stage, the vanillin content in roots gradually decreased, and at maturity stage, the content dropped to 2900-3230 μg/kg. The vanillin content in the leaves reached its peak at maturity stage. The vanillin in Oryza sativa grains started to accumulate continuously from the dough stage and reached its peak at maturity stage. In addition, at the late stage of reproductive growth, the vanillin content in the upper part of the plant (flag leaves and the upper part of the stem) was significantly higher than that in the lower part of the plant (lower leaves and the lower part of the stem), and the vanillin content in Oryza sativa husk was extremely significantly higher than that in the brown Oryza sativa. Conclusion This study confirms that vanillin has a natural background throughout the whole growth period of Oryza sativa, and vanillin is endogenously produced for the first time. Its content shows stage-specific and differential changes at different parts and growth stages. It is speculated that it may be a natural growth regulator of Oryza sativa.

Objective To establish a method for determining the volatile components of lubricating oil mixed in edible oil by headspace-gas chromatography-mass spectrometry. Methods The 1.0 g oil sample was directly taken into a 10 mL headspace bottle, then capped and sealed. Headspace-gas chromatography-mass spectrometry analysis was carried out at 90 ℃ equilibration for 20 min. Qualitative analysis was performed on 5 kinds of compounds: 4-methyl-2-pentanol, isooctanol, nonane, undecane and dodecane, while quantitative analysis was performed on isooctanol, nonane, undecane, and dodecane. Results The 4 kinds of quantitative compounds showed good linear relationships within the range of 0.5-8.0 mg/kg, and the correlation coefficients were all above 0.9980. Soybean oil was used as the sample for the spike recovery experiment. The recoveries of nonane, isooctanol, undecane, dodecane were 91.5%-98.2%, 81.9%-92.7%, 92.8%-94.6%, 89.3%-93.7% respectively and the relative standard deviations were all less than 10%. In the 5 kinds of edible oils: Soybean oil, peanut oil, rapeseed oil, corn oil and sunflower seed oil, the limits of detection of nonane, isooctanol, undecane, dodecane were 0.006-0.013 mg/kg, 0.016-0.045 mg/kg, 0.011-0.020 mg/kg, 0.020-0.036 mg/kg respectively. Conclusion This method has the advantages of simple operation and rapid detection, and does not have high requirements for the instrument, which can be carried out in general laboratories, and is suitable for the screening of trace lubricating oil contamination in edible oil.

Objective To evaluate the residual levels of tolfenpyrad and diafenthiuron in Brassica oleracea and assess the chronic dietary intake risk. Methods Brassica oleracea samples sprayed with 30% diafenthiuron·tolfenpyrad suspension concentrate were collected. The pesticide residues were detected using dispersive solid phase extraction coupled with ultra performance liquid chromatography-triple quadrupole tandem mass spectrometry. Based on the detection results, the chronic dietary intake risk was calculated using a risk probability formula, and a safety assessment was conducted. Results When 30% diafenthiuron·tolfenpyrad suspension concentrate was applied once at the maximum recommended dose of 180 g a.i./hm² with a 7-day pre-harvest interval, the residual concentrations of tolfenpyrad and diafenthiuron in Brassica oleracea were <0.01-0.39 mg/kg and 0.03-0.12 mg/kg, respectively. Both pesticide residues were below China’s maximum residue limits (MRLs) (0.5 mg/kg for tolfenpyrad and 2.0 mg/kg for diafenthiuron). Based on China’s pesticide registration and usage data, the national estimated daily intake of tolfenpyrad and diafenthiuron for the general population was 0.2215 mg and 0.0967 mg, respectively, with risk quotient of 58.6% and 51.2%, both below 100%. This indicated that the dietary intake risk was within an acceptable range. Conclusion When 30% diafenthiuron·tolfenpyrad suspension concentrate is applied at the recommended dose with a 7-day pre-harvest interval for controlling Plutella xylostella in Brassica oleracea, the pesticide residues in harvested Brassica oleracea comply with food safety standards. The long-term dietary intake risk for the general population is controllable, ensuring safe consumption.