Objective To establish a method for the simultaneous detection of hypoxanthine, guanine, xanthine, and adenine in edible fungi by high performance liquid chromatography, and use this method to the analysis of commercially available edible fungi. Methods The purines (hypoxanthine, guanine, xanthine, and adenine) from edible fungi were extracted by using acid hydrolysis. The chromatographic column was selected based on the resolution and peak shape of the 4 kinds of purines. Detection conditions, including the mobile phase ratio, flow rate, column temperature, and injection volume, were optimized, and the methodology was validated. Results The results showed that using Insert Sustain AQ-C₁₈ column with a mobile phase consisting of 50 mmol/L ammonium acetate solution (pH 4.0) and methanol (V:V=97:3), at a flow rate of 0.6 mL/min and the column temperature of 30 ℃, with an injection volume of 10 μL and detected at 254 nm, the 4 kinds of purines could be completely separated with good peak shapes. And the methodological validation results showed that this method exhibited a good linear relationship within the detected range. Conclusion A high performance liquid chromatography method is established through the optimization of detection conditions, which effectively differentiates and simultaneously detects the 4 kinds of purines in edible fungi. The content of hypoxanthine and xanthine (uric acid precursor substances) are very low or undetectable in the detected edible fungi. Based on the purine intake guidelines in the Encyclopedia of Chinese nutritional science, the dietary intake of the currently available commercial edible mushrooms is determined.

Objective To achieve rapid and non-destructive detection of lactic acid and total acidity during the fermentation process of sour meat. Methods Utilizing hyperspectral imaging technology, spectral reflectance images in the range of 408 to 1049 nm were collected to obtain spectral information of sour meat at different fermentation stages. After extracting the reflectance spectra from the regions of interest in the images, the kennard-stone algorithm (KS) was employed to divide the data into training and testing sets. The raw data underwent preprocessing through standard normal variate transformation (SNV) and multivariate scatter correction (MSC), followed by model establishment using partial least squares regression (PLSR). Feature wavelengths were extracted using the successive projection algorithm (SPA), competitive adaptive reweighted sampling (CARS), and uninformative variable elimination (UVE). Models were developed based on PLSR and compared with full-wavelength prediction models. Results The optimal prediction model for lactic acid in sour meat was SNV-CARS-PLSR, with a coefficient of determination (R²) of 0.9113 and a root mean square error of cross-validation (RMSECV) of 0.7236 for the training set, while the testing set yielded an R² of 0.9104 and RMSECV of 0.7342. The MSC-CARS-PLSR model for total acidity demonstrated the best predictive performance, with training set R² and RMSECV values of 0.9307 and 0.6782, respectively, and prediction set R² and RMSECV values of 0.8682 and 0.6907. Conclusion The models constructed using hyperspectral imaging technology have the potential to enable rapid and non-destructive detection of lactic acid and total acidity in sour meat, indicating significant application value.

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 establish an analytical method for determining γ-amino butyric acid content in foods of plant origin by high performance liquid chromatography. Method Foods samples were pre-column derivatized with 4-dimethylamino-azobenzene 4-sulfonyl chloride, orthogonal experiments were designed and methodological verification was carried out based on extraction solvent, solid-liquid ratio, extraction method and extraction time. The results of γ-amino butyric acid were analyzed by detecting different plant-derived foods and comparing with instruments. Results The results showed that the optimal conditions were determined as 60% ethanol solution, which was extracted by water bath (40 ℃) or ultrasonic for 30 min at 1:25 (g:mL) solid-liquid ratio. The separation of γ-amino butyric acid was achieved on C₁₈ column (250 mm×4.6 mm, 5 μm) using acetonitrile+sodium acetate solution (20:80, V:V) as the mobile phase at a flow rate of 1.0 mL/min. The absorption wavelength of γ-amino butyric acid was 436 nm and column temperature was set at 30 ℃, respectively. The linear range of γ-amino butyric acid was 1.092-131.064 μg/mL. The relative standard deviation of γ-amino butyric acid was all less than 5.0% in pitaya (white heart), tomato, and malt. The average recovery rate of γ-amino butyric acid was between 95.80%-104.36%, indicating that the method had good precisions and high recoveries. Conclusion The method established in this study has good repeatability and high accuracy, and can accurately quantify the content of γ-amino butyric acid in foods of plant origin.

Objective To establish a rapid identification model for 5 different types of vegetable oils (Camellia oil, soybean oil, corn oil, sunflower seed oil and peanut oil) and adulterated Camellia oil, using attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) and chemometrics methods such as cluster discriminant analysis. Methods The 99 samples of 5 different types of vegetable oils, including Camellia oil, soybean oil, corn oil, sunflower seed oil, and peanut oil were collected. According to the mass percentage of 5%-95%, soybean oil, sunflower seed oil, corn oil, 1:1 corn soybean oil, and palm oil was mixed into the Camellia oil, and 196 samples of the adulterated Camellia oil were obtained. Their infrared spectrum were collected in 600‒4000 cm^‒1 region. The models for partial least squares discriminant analysis (PLS-DA), principal component analysis discriminant analysis (PCA-LDA), K-nearest neighbor (KNN), and data driven soft independent modeling of class analogy (DD-SIMCA) were established and compared to determine the optimal recognition model. Results The infrared spectra of each sample group had similar characteristic peaks, peak positions, and peak shapeswere with slight differences. The discriminant model established by DD-SIMCA could completely separate Camellia oil samples from those of other types of vegetable oil. By comparison of PLS-DA, PCA-LDA, and KNN models, it was found that the predicted values of each sample in the training and testing sets of the classification of 5 types of edible vegetable oils samples using PLS-DA and PCA-LDA models were accurate and reliable. Except for peanut oil, the recognition and prediction accuracy of the training and testing sets of other edible vegetable oils were both 100.0%. The quantitative analysis of Camellia oil adulteration using ATR-FTIR combined with PLS could be accurately carried out, which could be used for qualitative and quantitative analysis of adulterated soybean oil, corn oil, sunflower seed oil, etc. The results were reliable, and the lowest limit of detection could reach 5%. Conclusion Adulterated Camellia oil can be determined accurately and efficiently based on ATR-FTIR combined with chemometric methods.

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.

In recent years, bioactive peptides with potential edible values have received widespread attention as consumer demand for functional foods grows. The bioactive peptides in fermented soybean foods (FSF) have attracted much attention because of their safe and non-toxic properties. Nowadays, a large number of FSF peptides have been identified through isolation and purification, which not only contain rich nutritional value, but also have a variety of physiological activities such as hypoglycemia, hypotension, antioxidant and antimicrobial activities, and have a good prospect for development in the field of food and health care products. This paper systematically classified and analyzed the biological activities of the active peptides in FSF in the light of the research progress of FSF in recent years, summarized the separation and purification methods of FSF peptides, and summarized the hypoglycemic mechanism of the active peptides in FSF, in order to provide ideas for the deeper study of FSF, and to provide theoretical foundations and support for the production of FSF active peptides and their development and application in the field of functional foods in the future.

Houttuynia cordata, known as a dual-use plant for both medicine and food, contains various functional components such as flavonoids and polysaccharides. It exhibits multiple bioactivities, including antibacterial, antiviral, anti-inflammatory, antioxidant, anticancer, and immune-regulating effects. The mechanisms underlying its bioactivities are complex and involve the regulation of multiple biological signaling pathways. Currently, Houttuynia cordata is widely used in traditional medicine, functional foods, and cosmetics. Its diverse bioactivities and complex mechanisms suggest a broad application potential. However, further in-depth studies are necessary to elucidate its specific mechanisms of action and ensure safety, thereby promoting its applications in the fields of medicine and health care. This article reviewed the biological activity and mechanism of action of Houttuynia cordata, and summarized the current application status of Houttuynia cordata in medical and healthcare fields, in order to provide reference for further development of Houttuynia cordata.

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.

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.