Abstract:Freshness is an important evaluation index of fresh food in the process of storage, transportation and sales. Conventional food packaging fails to meet the requirements of consumers for food freshness monitoring. The emergence of intelligent packaging technology makes it possible to detect freshness. Intelligent packaging technology uses indicators and sensors to monitor the physical, chemical and biological changes of food at storage to reflect the state of packaged food or the environment during transportation and storage. This paper introduces the principle, key technology and research progress of intelligent packaging technology in the freshness detection during the storage and transportation of fresh food from the indicators and sensors. The problems of intelligent packaging technology are finally summarized and the future development is prospected.

Abstract:Metrological traceability is very important for ensuring data validity of food safety inspection. The validity of inspection results was evaluated according to the contribution of different traceability factors based on the establishment of traceability system for food safety inspection. The appropriate control level was established and the quantitative traceability model was proposed in the fields of food physics and chemistry, microbiology and molecular biology. According to the traceability model, the important traceability elements, such as reference material, important equipment, and hierarchy schemes were assessed, analyzed and studied on the common inspection parameters/items and method standards used in the food safety inspection laboratories, forming a metrological traceability data frame and constructing the software system platform of the food safety testing measurement traceability. It's expected to provide a data-sharing platform for food safety inspection laboratory and establish a scientific and systematic metrological traceability system of food safety inspection.

Abstract:In this paper, the antioxidant capacity of loach protein polypeptide was studied by antioxidant experiments. Experiments showed that loach protein polypeptide in vitro has a certain ability to antioxidant. In the antioxidant experiment in vivo, SOD activity in high-dose group was increased by 36.6%, 28.1% and 22.3%, GSH-Px activity was increased by 43.2%, 132.2% and 92.5%, respectively, while MDA level was decreased by 16.2%, 18.3% and 26.2%, respectively. The experiment showed that loach protein polypeptide could improve the activities of SOD and GSH-Px in serum, liver and heart tissue of mice, and reduce the level of MDA in tissue. Liver tissue section showed that loach protein polypeptide had a certain effect on mice liver from oxidative stress damage. The experimental results showed that loach protein polypeptide could inhibit the damage caused by oxidation to a certain extent, and improve the antioxidant capacity of the body. The results provided reference for loach protein and its deep processing products.

Abstract:Fast, efficient and accurate molecular biological detection is very important in pathogen detection. Nucleic acid extraction is the basis of molecular detection. At present, the commonly used magnetic bead method, which takes many operating steps, is time-consuming and inconvenient for rapid detection on site. Microfluidic technology has the characteristics of rapidness, integration and miniaturization, which can provide an effective platform for rapid nucleic acid extraction and rapid detection. Based on the magnetic bead nucleic acid extraction method in the principle of solid phase extraction, a microfluidic chip for DNA extraction from various food-borne pathogens was designed. The chip mainly included a lysis chamber, a cleaning chamber, an elution chamber, a suction hole, a vent, a pneumatic valve, a capillary valve and other accessories, which could complete operations such as the extraction and purification of nucleic acid and the sequential loading of food-borne pathogens. In order to increase the concentration of nucleic acid extraction, the hydrophilization treatment of chip channel, the incubation time, magnetic bead mixing times and elution time during extraction process were optimized. The results showed that the best incubation time on the chip was 9 min, the best mixing times was 9 times, and the best elution time was 20 min. The nucleic acid concentration of ，Escherichia coli, Salmonella and Listeria monocytogenes extracted on the chip was high and could be used for PCR amplification and gel electrophoresis detection. This method has the advantages of low reagent consumption and low probability of contamination, and could be used for preparation of integrated chip for nucleic acid extraction and amplification.

Abstract:Based on Au@PDA core-shell nanoparticles (NPs) and the fluorescence quenching toward quantum dots, a dual-signal readout mode lateral flow immunoassay strip (LFIA) was fabricated for qualitative or quantitative determination of tebuconazole in fruits and vegetables. The effects of the preparation of Au@PDA and Au@PDA-antibody complex, the load of sensing elements and buffers of the strip were investigated on the strip sensitivity. Under the optimal conditions, the qualitative detection limit of tebuconazole by the naked eyes was 1 μg/mL in colorimetric mode and 100 ng/mL in fluorescent detection mode. The developed strip was applied in the tebuconazole detection in cucumber samples. And the results showed the interference of sample matrix could be eliminated by an appropriate dilution of cucumber sample extract. The limit of detection for tebuconazole in cucumber was 0.8 mg/kg, meeting the limit requirement of national safety standard.

Abstract:To make full use of the nutritional components of red jujube and wolfberry, a kind of soaked wine was made by using red jujube and wolfberry through cold soaking in distilled wine. The nutritional components and antioxidant capacity of red jujube wolfberry-soaked wine were detected and analyzed in vitro. The results indicated that the soaked wine was rich in polyphenol, flavonoids, free amino acids, organic acids, fatty acids, mineral elements and other bioactive components. The content of free amino acids was 1.66 g/L, and the enriched organic acids were lactic acid, succinic acid and adipic acid. The soaked wine has a strong scavenging ability of DPPH radicals, hydroxyl radicals, superoxide anion radicals and ABTS radicals. In this study, multi-type nutritional components were obtained in the red jujube wolfberry-soaked wine via a simple and convenient processing method compared with the distilled wine, providing a new idea for the comprehensive utilization of jujube and wolfberry.

Abstract:For investigating the effects of pH on the binding between protein and polyphenols. The binding energy and binding mechanism between epigallocatechin gallate(EGCG) and β--lactoglobulin at pH 2, 5 and 8 were respectively studied using molecular docking and molecular dynamics simulation. EGCG mainly bound to 3 sites of β--lactoglobulin. The docking site with the highest binding energy was used for 150 ns molecular dynamics simulation. It was found that the fluctuation of small molecules was larger than that of protein, especially at pH 2, however, the fluctuation of small molecules did not affect the stability of protein structure. The hydrophobic surface area, the content of α-helix and β--sheet of protein were lowest at pH 5. The highest binding free energy of small molecules to protein was detected at pH 5, while the lowest at pH 8. The highest value was mainly due to the strongest hydrophobic force, hydrogen bond and van der Waals force at pH 5. The difference of pH would affect the surface structure of protein, especially the binding site, thus affecting the binding energy, binding site, and binding posture between protein and small molecule.

Abstract:The emulsifying properties of egg yolk (EY) are easily affected by processing factors. Soy protein isolate (SPI) assisted with ultrasonic treatment was used to improve its emulsification. The emulsifying properties of EY and the properties of yolk protein improved by SPI were explored under different ultrasonic power. The results showed that the addition of SPI in EY significantly improved the emulsifying activity index (EAI) and emulsifying stability index (ESI) of EY( P<0.05). Ultrasonic power further improved the emulsification of EY-SPI. Under 150 W ultrasonic treatment, the ESI of EY-SPI emulsion was significantly higher than that of other groups( P<0.05), and the particle size and emulsification index were significantly decreased( P<0.05). The interfacial protein adsorption capacity was significantly increased( P<0.05), and the electrostatic repulsion was significantly increased( P<0.05). The emulsion droplets were more evenly distributed. Therefore, ultrasound-assisted SPI could effectively improve the emulsification of EY.

Abstract:A strain of Bacillus subtilis JD-014 with aerobic denitrification function was isolated and screened out from a river course in this study to treat and remove the nitrogen pollutants in food industrial wastewater in a green and environmentally friendly way. The aerobic denitrification pathway within this strain was verified by the gaseous nitrogen production, the nitrogen balance calculation and the functional enzymatic activity measurement during the nitrogen removal process. The effect of different environmental factors on its nitrogen removal performance was investigated as well. The results showed that the nitrogen removal rate of JD-014 was 0.56 mg/（L·h） when sodium nitrate (50 mg/L) was used as the sole nitrogen source. The strain was found to partly transfer the NO₃^--N into N₂ accompanied by the detection of related functional enzyme activity. The optimal conditions for JD-014 to achieve the best nitrogen removal performance were carbon source of sodium succinate or sodium citrate, C/N ratio of 10 to 25, temperature of 37 ℃, shaking speed of 150 to 200 r/min, and salinity of less than 1%. Moreover, JD-014 had great nitrite tolerance, and the nitrogen removal efficacy could be kept within 46.62%~99.92% when the concentration of NO₂^--N was 10~200 mg/L. These results suggested that the aerobic denitrifying B. subtilis JD-014 had great potential in the biological treatment of nitrogen pollution in food processing wastewater.

Abstract:The magnetic covalent organic framework was synthesized quickly and easily by the co-precipitation method and characterized by Fourier transform infrared spectroscopy and transmission electron microscopy. A new method for the determination of benzo[a]pyrene (BaP) in roast meat by magnetic solid phase extraction-high performance liquid chromatography was developed based on the optimization of experimental conditions such as adsorbent dose, extraction time, desorption solvent, desorption time and volume. The linear range of the method was 0.5~100.0 μg/L (R²=0.999 8), the limit of detection (S/N=3) and the limit of quantitation (S/N=10) were 0.14 μg/L and 0.47 μg/L, respectively. The relative standard deviations (RSDs) of the intra-day (n=5) and inter-day(n=5) were 3.5% and 3.9%, respectively. On this basis, this method was successfully applied to the determination of BaP in roast meats (grilled fish, beef and mutton) and BaP was detected in all three samples. The recoveries were in the range from 76.0% to 123.4% at three spiked concentrations (10.0, 20.0, 30.0 ng/g) by standard addition method, and the relative standard deviation was 1.7%~ 10.6%.

Abstract:The difference between the volatile components in the muscles of grass carp fed with spearmint stems and leaves and the control grass carp was distinguished. In this experiment, fresh spearmint (Mentha spicata L.) stems and leaves in the fish-flower (mint) symbiosis closed-loop system were fed to grass carp at 10% of the fish body mass together with the conventional feed. The fingerprint and qualitative analysis of volatile organic compounds of grass carp fed with spearmint and peppermint and control grass carp were conducted using gas chromatography-ion mobility spectrometry technology. 129 kinds of VOCs could be detected in the stems and leaves of spearmint, and 30 kinds identified VOCs were mainly alcohols, ketones and aldehydes. Among them, the content of the leaves was relatively high. 83 kinds of VOCs were detected in mint feeding and control grass carp, and 45 kinds of VOCs could be qualitatively identified. From the fingerprint and qualitative analysis, it was found that the contents of dipentene, phenethyl alcohol and linalool in mint feeding grass carp were higher than those of the control. The contents of odorous o-cresol, seawater and fishy trans-2-pentenal were greatly reduced. Moreover, linalool and isovaleraldehyde in 6 kinds of VOCs were detected in peppermint and significantly transferred to the feeding grass carp, which greatly reduced the original ethyl 2-methylbutyrate and 2-ethylfuran content in the control grass carp. It was further confirmed by principal component analysis that the VOCs difference between the mint feeding and the control grass carp was significant, and could be grouped into one category. The content of VOCs in the leaves of spearmint was much higher than that in the stems. The content of VOCs in the grass carp fed with mint was much higher than that in the control grass carp. The transfer of linalool with woody and floral characteristics and isovaleraldehyde with the characteristics of apple and peach flavor to the grass carp fed with mint was observed and their contents increased, which reduced some fishy smell substances affected the flavor of grass carp such as o-cresol and trans-2-pentenal. It could provide a theoretical basis for the scientific and directional utilization of medicinal and edible plants of mint and the improvement of volatile flavor substances of aquatic products.

Abstract:The samples of Potentilla anserine L. from seven different producing areas in Qinghai were used to study the differences, principal component analysis and quality comprehensive evaluation of nutritional components, providing a basis for the development and utilization of Qinghai Potentilla anserina L. as food raw material or product excipients. SPSS 19.0 was used to conduct principal component analysis and multiple comparative analysis of nutrients of Potentilla anserina L. from seven different producing areas in Qinghai, and the index components contributing greatly to the quality of Potentilla anserina L. were comprehensively evaluated. In addition, the differences of key nutrients between Potentilla anserina L. from Qinghai and other foods were compared and analyzed. The results showed that there were differences in the index nutrients among the samples, but with the characteristics of 'high protein, high dietary fiber, low fat, very low sodium, rich in amino acids and fatty acids, rich in nutrition and various mineral elements'. Compared with nutrients in other foods, it was found that the contents of dietary fiber, vitamin B₂, vitamin C, Ca, K and Na in Potentilla anserina L. were high, while the contents of fat, starch and energy were low. The top three Potentilla anserina L. were from Nangqian county in Yushu tibetan autonomous prefecture, Guinan county in Hainan tibetan autonomous prefecture and Huangyuan county in Xining city. It was found that the differences of nutrient mass fraction in Potentilla anserina L. from varied producing areas in Qinghai were related to the local altitude, and was closely related to the climatic factors corresponding to different altitudes. It might also be related to the varieties, breeding, genetic improvement and ecological adaptability. This study indicated that Potentilla anserina L. from Qinghai had favorable nutritional value and development prospect, which could provide a basis for its quality control.