Objective To establish an analytical mehod for the determination of nicotinamide mononucleotide (NMN) and nicotinamide adenine dinucleotide (NAD⁺) in health food by high performance liquid chromatography. Methods Determination was performed on Waters BEH-Amide column with mobile phase consisting of 0.1% phosphoric acid solution-acetonitrile (gradient elution). The flow rate was 1.0 mL/min, and the sample size was 2 μL. The column temperature was 35 ℃, and the detection wavelength was set at 263 nm. Health food was extracted with 60% methanol solution in ultrasonic water bath for 10 min. The extract was filtered through micoron filter, and analyzed by high performance liquid chromatography. Results The results showed that NMN and NAD⁺ exhibited excellent linear relationships, the correlation coefficient (r) was over 0.999 in the range of 10-1000 μg/mL. The method limit of quantitation was 0.50 g/kg. Recoveries were ranged from 95.9% to 98.8%, and relative standard deviations were ranged from 1.19% to 3.05%. Conclusion This method is accurate and suitable to determine NMN and NAD⁺ in health food.

Objective To develop a highly sensitive detection method suitable for accurate qualitative and quantitative analysis of monosaccharide composition in edible fungi polysaccharides. Methods Four kinds of edible fungus polysaccharides samples: Lentinus edodes, Pleurotus eryngii, Hypsizygus marmoreus and Auricularia auricula were selected, after hydrolyzing with trifluoroacetic acid, and deriving with acetic anhydride, the sample was analyzed by gas chromatography-mass spectrometry (GC-MS/SIM). The specificity, precision, linear range, limits of detection (LOD) and limits of quantification (LOQ) of this method were investigated with mixed standards of 7 kinds of monosaccharides. At different m/z, the best linear relationship was used as the standard to select the most suitable quantitative ion for each monosaccharide. The stabilities and recoveries of the method under selected ion monitoring (SIM) mode were investigated using edible fungus polysaccharide samples. Results The results showed that m/z 115, m/z 103, m/z 115, m/z 115, m/z 115, m/z 115 and m/z 103 were selected as the characteristic quantitative ions of the corresponding derivatives of ribose, rhamnose, arabinose, xylose, mannose, glucose and galactose, respectively. The separation of each monosaccharide was greater than 1.2, and the linear relationship between each monosaccharide in SIM mode was good between 10.00-50.00 μg/mL, and the correlation coefficient (r²) was greater than 0.998. The LOD and LOQ were 5.75-22.23 ng/mL and 17.26-66.67 ng/mL, respectively. Using monosaccharide mixed standard and lentinan as sample matrix, it was proved that this method had good precision and stability, and the average recovery of each monosaccharide was between 94.4% and 101.3% under different standard adding levels. And the rationality of selecting the above characteristic ions was discussed by mass spectrometry analysis. Conclusion This method has good separation, precision and stability, and its sensitivity is higher than most similar detection methods reported so far. It is suitable for the detection of monosaccharide composition in various edible fungi polysaccharides.

Objective To screen the crop varieties with low accumulation of heavy metal Cd suitable for cultivation in Qinghai and evaluate of their agricultural product safety. Methods Through field experiments, 9 crops, including barley, oilseed rape and broad bean, were planted in heavy metal-contaminated arable land in a field trial to analyze the Cd content in the roots, plants, seeds and corresponding soils of different crops. Cd content of different crop samples was measured by inductively coupled plasma atomic emission spectrometer (ICP-OES) after digestion in a graphite furnace. The enrichment capacity of each tissue and organ of the crop was analyzed by the enrichment coefficient method, and the non-carcinogenic health risk of Cd in crop seeds was evaluated by the target hazard quotient (THQ) method. Results The soil Cd content of barley and wheat exceeded the standard, but the seed Cd content of all crops met the national standard; the Cd enrichment capacity of wheat roots and plants was lower than that of the other crops, and the lowest soil Cd enrichment capacity of crop seeds was found in oats and wheat; there was no health risk for adults due to the intake of Cd from the edible parts of the 6 kinds of crops, and there was a health risk for children due to the intake of Cd from the edible parts of barley and potatoes. Conclusion Oilseed rape and oats is a kind of Cd low-accumulating crop suitable for local cultivation, which can ensure the safe utilization of local farmland. Therefore, this study can provide a scientific basis for screening crop varieties with low Cd accumulation and applying them on a large scale to polluted croplands in Qinghai.

Supercritical carbon dioxide extraction technology, as a unique, clean, efficient, and energy-saving separation method, can solve many defects in traditional extraction techniques such as the use of toxic organic reagents, high energy consumption, and low extraction yield. Therefore, it has good application prospects in food processing. As one of the 3 kinds of major nutrients of human body, oil not only maintains the normal physiological function of human body, but also has many beneficial physiological functions, which is of great value to improve human health and prevent diseases. Therefore, this article focused on supercritical carbon dioxide extraction technology, systematically summarized supercritical carbon dioxide extraction's concept, mechanism, process flow, characteristics and influencing factors, as well as the research status in recent years regarding its application in plant oils such as wheat germ oil, rice bran oil, and soybean germ oil, as well as animal fats like fish oil and insect oil, aimed to provide a theoretical reference for the scientific research and food processing applications of supercritical carbon dioxide extraction technology.

Food safety is a major strategic content related to people's livelihoods and achievement of the modernization of national governance. After the extensive scientific research and regulatory practice, many iconic academic achievements have been achieved, and the relatively systematic theoretical systems, methodological standards and regulatory strategies for food safety have been established. The traditional food safety mainly relies on the methodological development, safety detection and risk monitoring, depends on the laws, regulations, and standards as regulatory basis, utilizes propaganda, education, service and popularization of science as auxiliary means, and combine the rectification and improvement. Due to the complex interactions between humans and food, there are many characteristics involved in food safety like uncertainty, relativity and regionalism. At present, the connection between the food safety research and regulation is not close enough, and the food safety work still needs a lot of innovative exploration, practice and the new quality productivity empowerment. Based on the author's recent research, teaching, investigation, and regulatory practices in food safety, this paper started from the root causes of food safety issues, summarized and discussed the main challenges faced in the current food safety work from the perspective of the risk prevention and control throughout the entire process, and proposed the directions that could be focused on the food safety research, teaching and regulation in future, which would help achieving the precise prevention and control of food safety across the entire region.

Starch as an important component of edible films, has many advantages such as safety, degradability, low cost, and wide availability. Chitosan is widely used in food packaging films due to its good biodegradability, antioxidant, antibacterial, and good film-forming properties. The application of chitosan in starch based edible films and the development of packaging materials with good biodegradability and safety is a research hotspot in the food packaging industry. This paper reviewed the structure, film-forming properties, and biological activity of chitosan, and elucidated the film-forming mechanism of chitosan starch based edible films and the film-forming properties of chitosan in different types of starch matrices, discussed the application of chitosan-starch composite edible film in meat, fruits, vegetables, and other foods. With the deepening of research, chitosan starch based edible packaging film has broad development prospects in the future. This paper provides a basis and direction for the application of chitosan in starch based edible film, and provides a good theoretical basis for its application in new food packaging.

Objective To achieve accurate and non-destructive detection of Zea mays L. seed maturity by applying hyperspectral imaging technology combined with multimodal fusion methods. Methods Hyperspectral images of high and low maturity Zea mays L. seeds were acquired. The cascade algorithm of bootstrapping soft shrinkage and successive projections algorithm (BOSS-SPA) was used for feature wavelength extraction, while the gray-level co-occurrence matrix method (GLCM) was used for image texture feature extraction. Five feature parameters—energy, entropy, correlation, homogeneity and contrast were selected to integrate the spectra with the image data in a feature level fusion. Results The partial least squares-discriminant analysis (PLS-DA) and least squares support vector machine (LS-SVM) were used to establish a Zea mays L. seed maturity classification model. The use of Savitzky-Golay convolution smoothing-standard normal variable transformation (SG-SNV) was identified as the best spectral preprocessing method, and the 11 wavelengths extracted using the BOSS-SPA method showed good modelling performance, and the overall recognition accuracies of the model test set based on the fused data of the spectral images all reached over 95%. Conclusion Hyperspectral technology combined with multimodal feature fusion method is expected to provide a practical reference method for non-destructive detection of Zea mays L. seed maturity.

Objective To study the effect of n-3 polyunsaturated phosphatidylserine on the anti-apoptotic ability of rat hippocampal neuron cells (RHNC). Methods An apoptosis model using RHNC as the target and phorbol acetate (PMA) as the inducer was established. Using docosahexaenoic acid (DHA)/eicosapentaenoic acid (EPA) phosphatidylserine (DHA/EPA-PS) as a protective agent, the morphology of cells at different stages of apoptosis was observed under a laser confocal microscope after staining with acridine orange. The effect of n-3 polyunsaturated phosphatidylserine, represented by DHA/EPA-PS, on the anti-apoptotic ability of RHNC was studied at the cellular level through the Annexin V-FITC/PI double staining experiment. Results An RHNC apoptosis model with a PMA concentration of 10.0 mg/L and an action time of 24 hours was established. The 15.0 mg/L DHA/EPA-PS showed the best cell pre protection effect, with an apoptosis rate of 11.46%±4.11%. Early and mid-stage apoptotic cells were fewer and did not produce late stage apoptotic cells. Cells pre protected with 15 mg/L DHA/EPA-PS exhibited intact morphology and nuclear membrane, and their protrusions were not affected by PMA. Conclusion n-3 polyunsaturated phosphatidylserine, represented by DHA/EPA-PS, has certain anti-apoptotic ability against RHNC. The study provides good data support for future research on the biological activity of phosphatidylserine.

Objective To study the difference of meat quality between adult and young Xueduo yaks. Methods Healthy adult and young castrated Xueduo yaks were selected to analyze the composition and content of conventional nutrients, edible meat quality, amino acids, fatty acids, vitamins and minerals in longissimus dorsi muscle. Results The moisture content of adult Xueduo yak meat was 72.89%, which was lower than that of young Xueduo yak meat. The crude protein, crude fat and crude ash contents of adult Xueduo yak meat were 4.99%, 86.67% and 38.54% higher than those of young Xueduo yak meat, respectively. Therefore, adult Xueduo yak meat had higher nutritional value. The edible meat quality of young Xueduo yak meat was excellent, and the color, taste and tenderness were better than those of adult Xueduo yak meat. Both adult and young Xueduo yak meat were high-quality protein sources. The contents of essential amino acids and total amino acids in young Xueduo yak meat were 5.95% and 14.00%, which were significantly higher than those in adult Xueduo yak meat, but adult Xueduo yak meat tastes more delicious. The fatty acid composition of young Xueduo yak meat was slightly better than that of adult Xueduo yak meat. In terms of vitamin and mineral composition and content, vitamin A in young Xueduo yak meat was significantly higher than that in adult Xueduo yak meat. The iodine content of adult Xueduo yak meat was significantly higher than that of young Xueduo yak meat. Conclusion The meat quality of young Xueduo yak is better than that of adult Xueduo yak. The growth cycle of young Xueduo yak is short, which can create higher economic value under limited forage resources. At the same time, it can improve the market competitiveness of yak meat and provide scientific and effective guidance for yak breeding in pastoral areas.

Objective To establish a solution for fungal culturomics in food by comparing the performance of 3 fungal culture media and optimising fungal culturomics techniques. Methods The 24 food samples and 2 proficiency test samples were tested using commonly used fungal culture media for food testing, including potato dextrose agar (PDA), rose Bengal agar, and a novel Pan Fungi medium (PF). The cultured fungi were isolated and identified using matrix assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). Results Yeast phase fungi could grow well on all 3 kinds of media, and the colony growth rate, colony morphology size and colony numbers had no significant difference. Filamentous fungi were able to grow well on the 3 kinds of medias, but growth rate and colony morphology were significantly different. There were 12 kinds of fungal species identified in the 24 samples, including 2 kinds of yeast phase fungi and 10 kinds of filamentous fungi. Conclusion With excellent accuracy and stability and self-limited growth of cultured colonies, PF fungal medium is favourable for isolation and identification of single colonies, and can be used as a supplement to the commonly used fungal medium for fungal culturomics studies in food.