Abstract:Food safety is a vital matter for the national welfare and people's livelihood. Safe food is produced under the strict supervision. To reinforce food safety, strengthening the capability of food safety supervision construction is the key. The team of professional inspectors is the foundation and guarantee of food safety supervision, which can also make up for the problems related to insufficiency of supervisory staff and lack of professional competence. Foreign developed countries and regions pay high attention to the team construction of high-quality and highly-specialized food inspectors. However, the construction of food inspector teams in our country is still under exploration. As one of the regions with the best food safety system in the world, Canada has a complete system of food inspector management policies and regulations, with well-defined inspection basis, qualification management and classification, education and training, duties and tasks, inspection procedures, assessment and management. This could be a significant reference for the construction of our food inspector teams. This article mainly studies the relevant management policies and regulations of the Canadian food inspectors. Combined with the current situation in our country, several suggestions for improving the construction of our food inspector teams at the specific work level are proposed.

Abstract:Resistant starch(RS), as a new type of dietary fiber, cannot be digested and absorbed by human stomach and small intestine, but it can be fermented and utilized by intestinal flora in colon and has various physiological effects such as reducing blood sugar and fat, preventing cardiovascular disease and colon cancer. These characteristics make it possible for RS to prevent diseases related to dyslipidemia and insulin secretion, and to develop weight loss foods and dietary therapies to treat type 2 diabetes and coronary heart disease. However, the content of RS in most natural foods is too low to achieve the effect of controlling blood sugar balance. Therefore, how to prepare RS and apply it to food has become a research hotspot in the domestic and foreign food industry. The preparation methods and digestive characteristics of five types of RS were reviewed, and the current application of RS in grain cooking, baking, frying and functional foods was introduced. In addition, the future research directions of RS were summarized to provide references for in-depth research of RS and development of RS-rich foods.

Abstract:Among the known mycotoxins, aflatoxin B₁ (AFB₁) is the most toxic, and its impact on food safety has caused widespread concern. To explore the degradation mechanism of AFB1 by Aspergillus niger FS10, different fractions of A.niger FS10(suspension, fermentation, spores, mycelium) were used to degrade AFB₁. The effects of AFB₁ stimulation on the degradation of A.niger FS10 were studied and the morphological changes of A.niger FS10 mycelium during the degradation process were observed under scanning electron microscope. Finally, the possible mechanism of AFB₁ degradation was explored by transcriptome technology. The results showed that AFB₁ could be effectively degraded by A.niger FS10, and the removal rate of AFB₁ was 98.65% after 72 h treatment. The spores of A.niger FS10 insignificantly affected the AFB₁ removal, but the mycelium had a certain adsorption capacity for AFB₁ and the fermentation broth had obvious effect on the removal of AFB1. After the induced stimulation of AFB₁, the degradation effect of A.niger FS10 was significantly improved, indicating that AFB₁ treatment could significantly improve the degradation ability of A.niger FS10 to AFB₁. The microstructure analysis showed that AFB₁ treatment affected the morphology of A.niger FS10 to a certain extent, but this effect gradually decreased with the treated time. Moreover, the transcriptomic analysis showed that AFB₁ treatment decreased the levels of some energy metabolism-related genes, which might be a self-protection mechanism of A.niger FS10. And the up-regulation of methionine synthesis genes suggested that the degradation of AFB1 might be related to the methionine synthesis process.

Abstract:To investigate the effect of three wall breaking methods on the antibacterial properties of sexual propagule (ascocarp and ascospore) extracts of Eurotium cristatum, ultrasonic method, germination method and glass bead-beating method were used to prepare the aqueous extracts. The antibacterial activities of extracts against Staphylococcus aureus and Escherichia coli were determined by the disk diffusion test. The results suggested that the ascocarps were much more fragile and their aqueous extracts prepared by glass bead-beating method displayed stronger antibacterial activity than those of ascospores. The radius of inhibitory zone of ascocarp extracts against Escherichia coli and Staphylococcus aureus were 5.8 mm and 12.6 mm, respectively. The highest spore breakage rate was 94.8% when glass bead-beating method was applied to disrupt ascospores and the obtained extracts displayed strong antibacterial activity. However, the extracts obtained by the other two methods showed insignificant antibacterial activities. Therefore, glass bead-beating method was the best method to extract the antibacterial substances from Eurotium cristatum sexual propagules among the three methods.

Abstract:Blakeslea trispora (B. trispora), an important filamentous fungus, is used industrially in the mass production of carotenoids. The lack of a deep understanding of the genetic background of B. trispora and the shortage of genetic manipulation tools have hampered the genetic studies of B.trispora and the biological studies of carotenoid synthesis. For B. trispora, protoplast transformation rate is low and the spore cell wall is thick, which cause difficulty in introducing exogenous vectors into the cell. To solve this problem, this study constructed a transformation system mediated by Agrobacterium tumefaciens (A. tumefaciens) infecting protoplast, and cloned ku80 gene which was related with the non-homologous end joining repair pathways at the same time, and then applied the transformation system in the knockout of ku80. A recombinant knockout vector pDH-85H3 was constructed by inserting ku80 knockout frame into the binary vector pDHt-sk. And then the vector pDH-85H3 was introduced into A. tumefaciens LBA4404 by chemical transformation. Finally, the protoplast of B. trispora was transformed by A. tumefaciens-mediated method. By hygromycin screening and PCR analysis, there were 18 transformants in which the knockout box was inserted into the genome out of 20 transformants, and the transformation rate was 90%. Further analysis indicated that there were 2 transformants in which homologous recombination occurred and the knockout rate was 10%. The result indicated that A. tumefaciens mediated protoplast transformation in B. trispora was feasible.

Abstract:The soluble dietary fiber (SDF) of oat bran with good physical and chemical properties prepared by microwave modification was added to fermented milk to study the effects of modified oat bran SDF on the number and stability of live lactic acid bacteria, pH value and acidity, coagulation time, texture, sensory quality, storage modulus, loss modulus and antioxidant activity of fermented milk. The results indicated that 4% addition of modified oat bran SDF could significantly increase the number of living lactic acid bacteria in fermented milk, improve the texture properties (P<0.05), favor the formation of gel network structure and shorten the coagulation time, however, excessive addition would affect the taste and stability of fermented milk. When the addition of modified oat bran SDF was 4%, the highest water holding capacity of fermented milk was up to 94.82%, and the hardness, viscosity, adhesiveness, elasticity and cohesion were the best. The scavenging ability of fermented milk to DPPH radical, hydroxyl radical and superoxide anion radical increased with the increase of modified oat bran SDF, and reached as high as 39.97%, 62.30% and 75.51%, respectively, significantly higher than that of the control group (P< 0.05). Modified oat bran SDF could significantly improve the quality and antioxidant activity of fermented milk. This study may provide a theoretical basis for the application of oat bran SDF and the development of functional fermented milk.

Abstract:Molasses, a by-product of sugar industry, was used as the raw material in this study to improve the added value and utilization of molasses, and a feed grade fruto-oligosaccharide processing technology was developed through the dual-enzyme reaction to use the sucrose from molasses. The optimal conditions for enzymatic preparation method of fruto-oligosaccharides were determined by single-factor experiments. The results showed that the optimal reaction conditions were as follows: temperature of 55 ℃, pH value of 5.5, reaction ratio between pectinase and fructosyltransferase of 20∶1 and reaction time for 10 h. The conversion rate of fruto-oligosaccharides was up to 45%. In addition, the viscosity gradually decreased to a stable value with the increased reaction time, which was beneficial for improving the conversion rate and subsequent drying process.

Abstract:This study aimed to analyze and compare the differences of metabolites between Lycium ruthenicum< Murr. and Lycium barbarum L.. Liquid chromatography mass spectrometry technique (LC-MS) was adopted to analyze the metabolites. A total of 6 982 metabolites were detected, including 2 704 negative ions and 4 278 positive ions. Principle component analysis (PCA) displayed that Lycium ruthenicum Murr. and Lycium barbarum L. could be distinguished. Analysis of differential metabolites revealed a total of 501 differential metabolites. Among the top 50 differentially expressed metabolites, 7 were flavonoids, and 6 were amino acids and polypeptides. 11 metabolic pathways were significantly enriched, 4 of which were associated with amino acid metabolism. This study provided a basis for in-depth understanding of the biosynthesis of amino acid metabolism and the differential utilization of Lycium ruthenicum Murr. and Lycium barbarum L..

Abstract:Based on the characteristics of aroma production and promotion of laccase synthesis, a carotenoid-producing strain of Rhodotorula mucilaginosa YG14 was screened from tobacco stems. After solid-state fermentation of Ganoderma lucidum, Rhodotorula mucilaginosa YG14 and co-cultured mixed stalks. The contents of cell wall materials were measured, the neutral aroma components were determined, and the sensory quality evaluation was performed on the stalks. The results showed that the solid fermentation fermented silk of the two strains co-cultured had significant improvements in cell wall material degradation, neutral aroma content, and sensory absorption compared to those of two strains alone. After solid-state fermentation of the co-cultured mixed bacteria, the total cell wall material of stems degraded to 37.20%, and the neutral aroma components content (mass fraction) increased by about 20.44%. The sensory evaluation showed that the sweetness was significantly improved, the woody flavor was significantly improved, the aroma was improved to a certain extent, the burning sensation was significantly improved, and the aroma was more mellow. It can significantly improve the quality of tobacco stems and increase its utilization rate in tobacco.

Abstract:In order to reasonably and scientifically evaluate the flavor characteristics of different grades (i.e., the premium model (Zunxiang), the first-grade model (Lexiang) and the popular model (Zizhu)) of ‘Fo Tiao Qiang’, the content of flavor amino acids and nucleotides in the three different grades were determined，and their flavor differences were analyzed by electronic tongue and gas chromatography-ion mobility spectrometry(GC-IMS). The results of electronic tongue research showed that the taste of Zizhu ‘Fo Tiao Qiang’ was richer, and the intensity of its umami and umami aftertaste were significantly higher than those of the other two ‘Fo Tiao Qiang’, but at the same time, the intensity of bitterness and bitter aftertaste were also higher. This result was consistent with the results of amino acids, flavor nucleotides, and the equivalent umami concentration(EUC). A total of 36 compounds were identified through GC-IMS, including alcohols, aldehydes, ketones, esters and other categories. Among them, the threshold of aldehyde compounds was low, greatly contributing to the overall flavor of ‘Fo Tiao Qiang’. The total content of volatile substances in the Zunxiang ‘Fo Tiao Qiang’ was higher than that of the Lexiang or Zizhu ‘Fo Tiao Qiang’. By analyzing the characteristic peak areas and PCA diagrams of different ‘Fo Tiao Qiang’, three different levels of ‘Fo Tiao Qiang’ could be well distinguished. The research results on the taste and flavor of different grades of ‘Fo Tiao Qiang’ could provide ideas and theoretical basis for the production, processing and utilization of ‘Fo Tiao Qiang’, and provide valuable guidance for the construction of fingerprint map, database and classification of volatile substances in the ‘Fo Tiao Qiang’.

Abstract:The effects of initial total acid content, ratio of liquid to material, thickness of fillets and pickling time on the acidification of channel catfish fillets were evaluated by using pre-dried channel catfish fillets as raw material and the prepared kaili red sour soup as pickling solution. The acidification prediction model of fish fillets with pH value as response value was established by Box-Behnken experiment. The sterilization curves of acidified fish fillets at different temperatures (85, 88, 91, 93，95 ℃) were determined, and the safe F values at different sterilization temperatures were determined by heat preservation experiments. The effect of different sterilization temperature on the shearing force of fish fillets was compared under the safe F value. When the ratio of liquid to material was 2∶1, 3 mm fillets could be acidified in 25 g/kg acid soup after 12 h. The curing rate could be significantly improved by increasing the initial total acid content, while the curing rate could be significantly increased in the later stage by increasing the ratio of liquid to material. The acidification rate of thicker fillets was slower in the early stage of pickling, but it was almost the same as that of thin fillets in the later stage. The acidified channel catfish fillets reached the commercial asepsis state when F value was 5 min. The shearing force of channel catfish fillets was significantly reduced after sterilization at 85 ℃ and 88 ℃, respectively, the shearing force of channel catfish fillets could be better maintained after sterilization at 91, 93 ℃ and 95 ℃, respectively. After acidification and sterilization at 91~95 ℃, the texture quality of channel catfish fillets could be well maintained.

Abstract:In Japanese diet, the pungent condiments are mainly made from Eutrema wasabi , Armoracia rusticana and mustard, which are in the Brassicaceae family . Eutrema wasabi , Armoracia rusticana and mustard were quickly and accurately identified in the study by the internal transcribed spacer 2(ITS2) technology, providing a reference for the technology used in the quality control of pungent products. In this study, three plant materials, i.e., Eutrema wasabi, Armoracia rusticana and white mustard, were used as the experimental materials to extract the genomic DNA, and the ITS2 sequence was obtained by PCR amplification using the universal primer ITS2_S2. After sequencing, bioinformatics analysis was performed for species identification. MEGA7.0 (Molecular evolutionary genetics analysis 7.0) analysis of ITS2 sequence showed that the K2P genetic distance (Kimura 2-parameter) of Eutrema wasabi , white mustard and horseradish was between 0.088 and 0.171, which were all higher than 0.01, and there were 36 interspecies variation sites, preliminarily inferring that ITS2 sequence could be used to distinguish the three species of Eutrema wasabi , mustard and horseradish. In addition, ITS2 sequences of Eutrema wasabi and its close relatives, such as Eutrema edwardsii, Armoracia rusticana and mustard, were obtained from GenBank. MEGA7.0 was used to analyze the interspecies sequence, calculate K2P and build evolutionary tree by Neighbor-joining (NJ). Eutrema wasabi and Eutrema edwardsii were gathered into a large branch. In the meantime, brown mustard, white mustard, and black mustard were gathered into a large branch. And Armoracia rusticana was alone as a branch. ITS2 sequence analysis of Eutrema wasabi and its close relatives, such as Eutrema edwardsii, Armoracia rusticana and mustard, showed that the genetic distance of K2P between species was between 0.030 and 0.105, which were all higher than 0.01. This study showed that ITS2 technology could be used to identify the relative species such as Eutrema wasabi, Armoracia rusticana and mustard. This technology can be used to identify and quantify the specific raw material ingredients of pungent condiments, providing a scientific basis for food quality control and food safety.

Abstract:This study analyzed Fu brick tea, and the ‘Golden flower’(Eurotium cristatum ) as well as the tea base without ‘Golden flower’ isolated from Fu brick tea, detecting their volatile compounds by sensory evaluation, solid-phase microextraction-gas chromatography-mass spectrometry(SPME-GC- MS), odor active value(OAV) and chemometric methods to explore the key aroma compounds and their source in Fu brick tea. The result of sensory evaluation indicated that the characteristic aroma of Fu brick tea was formed by the combination of aroma compounds from the ‘Golden flower’ and the tea base without ‘Golden flower’, and neither was dispensable. In total, 59 volatile compounds were identified and quantified in samples. Alcohols and esters were the dominant volatiles in Fu brick tea and the ‘Golden flower’. However, alcohols and aldehydes dominated in the tea base without ‘Golden flower’. Among them, 16 volatile components were aroma compounds of Fu brick tea as identified by OAV analysis. Combined with the multivariable statistics analysis, 7 volatile aroma components with significant content difference were screened out in the tea base without ‘Golden flower’ and the ‘Golden flower’. Hexanal and(E,E )-2,4-Octadienal originated from the tea base without ‘Golden flower’ mainly contributed to the grassy flavor in Fu brick tea, while benzyl alcohol, linalool, cedrol, 1-octen-3-ol and methyl salicylate originated from the ‘Golden flower’ mainly contributed to floral, woody, and the smell of mushroom and wintergreen in Fu brick tea.