Abstract:Wheat-dependent exercise-induced anaphylaxis (WDEIA) is a rare but potentially severe IgE-mediated food allergy. The symptoms are not induced by the intake of wheat alone. However, if ingestion of wheat is accompanied by the triggering factors such as exercise, non-steroidal anti-inflammatory drugs, alcohol and infection, allergic symptoms are elicited, including pruritus, urticaria, vascular edema, dyspnea, hypotension and even anaphylaxis. To avoid serious allergic reactions, timely and accurate diagnosis is particularly important. However, diagnosis is often missed or delayed due to the lack of knowledge concerning WDEIA. This review focused on the epidemiology, pathogenesis, clinical symptoms, diagnosis and therapy of WDEIA, aiming to raise the awareness of WDEIA and to improve the early diagnosis and effective prevention and treatment.

Abstract:Benzo[a]pyrene is a kind of polycyclic aromatic hydrocarbon and widely found in high- temperature processed food. Moreover, incomplete combustion of fuel in industrial production and daily life also produce a huge number of benzo[a]pyrene, which further contaminates food through water, air and soil source. Epidemiological investigation shows that benzo[a]pyrene is closely related to colon cancer, colon inflammation and other intestinal diseases. Therefore, this paper summarized in detail the content of benzo[a]pyrene in different foods and the related molecular mechanisms of colonic toxicity that induce colon cancer, colon oxidative damage, colon inflammation and intestinal flora imbalance, aiming to fully reveal the colonic toxicity of foodborne benzo[a]pyrene and to provide a reference for its toxicity control and protection of human health.

Abstract:The increase of nanoparticles in food enhances the exposure possibility of human to nanoparticles by oral ingestion. Therefore, it is very important to accurately assess the safety of orally ingested nanoparticles. This review summarized the effects of the interaction of common nanoparticles in food with food matrices and gastrointestinal tract on the physicochemical properties and biological responses of nanoparticles, providing a reference for an accurate safety assessment of nanoparticles.

Abstract:Within goat casein micelles, part of β-casein is bound to the micelle skeleton through hydrophobic interaction. The protein hydrophobic bonds are weakened at low temperature,contributing to the dissociation of β-casein from the micelles. Goat skim milk was used in this study, and the effects of temperature, equilibration time, pH and the addition of NaCl, sodium citrate and CaCl2 on the dissociation of ββ-casein from casein micelles were investigated, based on the indicators such as HPLC, SDS-PAGE and ICP-MS. The results showed that low-temperature induced the dissociation of β-casein from micelles, reaching an equilibrium state at 120 min. The reduction in temperature and pH, as well as the addition of sodium citrate induced the dissociation of colloidal calcium, also increasing the proportion of β-casein bound by hydrophobic bonds within the micelles, thus further promoting the dissociation of β-casein from the micelles at low temperature. The optimal selective dissociation of β-casein from micelles was achieved after 120 min of incubation at 4 ℃ and pH 6.0. The dissociation rate of β-casein, κ-casein and α-casein reached 41.8%, 19.9% and 15.2%, with the proportions of the dissociated parts of the three caseins being 68.2%, 24.4% and 7.4%, respectively. The above results can be applied in process optimization of cold microfiltration for the goat β-casein fractionation.

Abstract:The in vitro antioxidant capacity of coriander and its preventive effects on blood pressure elevation in rats induced by high-fructose and high-salt diet were investigated. The in vitro antioxidant activity of coriander was evaluated by measuring the ability to scavenge DPPH free radicals and hydroxyl free radicals, as well as the reducing ability. The preventive potential of coriander on blood pressure elevation induced by high-fructose and high-salt diet was assessed by conducting a rat experiment. Male SD rats were randomly divided into four groups. Rats in normal control group (NC) were fed with normal feed and water. Rats in model group(M), low-dose coriander group (LP) and high-dose coriander group (HP) were fed with high fructose (60%) feed and 2% saline. One week after the experiment, rats in LP and HP groups were daily administered with lyophilized coriander powder of 1 g/（kg·d） and 2 g/（kg·d）, respectively. The blood pressure of rats was measured at a fixed time every week. The mean arterial pressure(MAP) was calculated at the end of experiment, and the level of total cholesterol(TC), triglycerides(TG), high density lipoprotein(HDL-C) and low-density lipoprotein(LDL-C) in serum were also detected. The ethanolic extract of coriander showed excellent in vitroin vitro DPPH radical scavenging ability, hydroxyl radical scavenging ability and reducing ability. The results of in vivo experiment in rats showed that the lyophilized coriander powder effectively alleviated the increment of body weight and blood pressure induced by high-fructose and high-salt diet. The MAP of rats in M group (21.2 kPa) was significantly higher than that of the normal rats (15.8 kPa). After intervention for 6 weeks with lyophilized parsley powder under high-dose and low-dose, the MAP values remarkably decreased to the normal level, i.e., 15.7 and 14.5 kPa, respectively. Additionally, coriander effectively antagonized the abnormal alterations in serum TC, TG, HDL-C and LDL-C contents induced by high-fructose and high-salt diet. Coriander possesses excellent antioxidant capacity in vitro, and can effectively prevent the elevation of blood pressure in rats induced by high-fructose and high-salt diet.

Abstract:Traditional burnt rice is widely desirable, however, the rice cooker program is not yet mature. Seven characteristic volatile flavor components of burnt rice, i.e., hexanal, methylpyrazine and etc., were identified by gas-mass spectrometry combined with odor activity value. Among them, pyrazines and thiazoles contributed to the burnt flavor, and aldehydes and phenols contributed to the fragrance flavor. The content of scorched flavor substances and associated harmful substances (5-hydroxymethyl-2-furaldehyde and acrylamide) gradually increased with the increase of temperature and time of stewing rice. The pyrazines in rice tended to be stable after heating at 175 ℃ for 20min, while the content of 5-hydroxymethyl-2-furaldehyde and acrylamide in rice were only 1.71 mg/kg and 0.08 mg/kg, respectively. The formation and accumulation of α-dicarbonyl compounds such as methylglyoxal promoted the production of characteristic flavor components of burnt aroma, and Amadori compounds were more likely to be transformed into harmful products at extremely high temperature(above 200 ℃). This study can provide a scientific basis for the directional regulation of the flavor of burnt rice and the reasonable design of cooking procedure of electric rice cooker.

Abstract:This paper systematically studied the changes of water content, water distribution, yeast content, gas production capacity and gas holding capacity of frozen waffle dough during frozen storage period, and clarified the mechanism of quality change of frozen waffle dough. The experiment showed that the frozen storage time of frozen waffle dough had a significant influence on the product quality. When the storage time was 3 months, the yeast content, gas production capacity and gas holding capacity decreased by 28%, 23% and 36%, respectively. The different types of modifier (gluten, xanthan gum, HPMC, gellan gum) affected the frozen dough quality during frozen storage. The proper addition of the modifier effectively improved the products quality. The gluten and xanthan gum remarkably reduced the ice crystal mechanical damage and improved the dough fermentation ability. Compared with the control group, gluten powder increased yeast content by 131% and fermentation capacity by 210%, while xanthan gum increased yeast content by 107% and fermentation capacity by 181%.

Abstract:In order to compare the effects of deproteinization methods on the composition, structure and antioxidant activity of the dried adductor muscle polysaccharides, four deproteinization methods were applied to the polysaccharides extracted by hot water-assisted ultrasound method, including enzymatic hydrolysis, dilute alkali pretreatment, trichloroacetic acid(TCA) method and D-glucono-δ-lactone(GDL) method. The polysaccharide content, monosaccharide composition, amino acid composition, triple helix, microstructure and antioxidant activity in vitro of the four deproteinization groups were compared. The results showed that the polysaccharide content of TCA group was the highest, reaching （74.83±0.57）%. The monosaccharide composition of polysaccharides in the four groups was mainly glucose. The total amino acid content, polar amino acid content and non-polar amino acid content were higher in the GDL group. The polysaccharides of alkali-enzyme group and GDL group were in triple helix structure. The polysaccharides of dilute alkali group were dense and smooth, while polysaccharides of the other three groups were loose and porous. Comprehensively, the polysaccharide content of alkali enzyme group was higher and the antioxidant activity was better. Different deproteinization methods could affect the composition and antioxidant activity of polysaccharides extracted from adductor muscle.

Abstract:Bird’s nest is a traditional nourishing food with rich nutritional value, however, there are few reports on its digestive characteristics. The gastrointestinal digestion of stewed bird’s nest was simulated through in vitro experiments in this research. The results showed that the solubility of protein, total sugar acid after the digestion of stewed bird’s nest increased from 13.85% to 47.23%, from 7.49% to 39.02%, and from 18.69% to 44.24%, respectively. For sialic acid, 17.41% existed in free form, 11.85% bound to glycan and 14.98% bound to protein. The degree of hydrolysis of bird’s nest protein was 11.54%, and 50% of the peptides were oligopeptides. Monosaccharide composition analysis showed that the solubility of O-type glycoprotein was lower than that of N-type glycoprotein. Glycoprotein staining showed that glycoproteins were hydrolyzed into several bands between 3.7×10⁴~1.5×10⁵, and the glycochain was tightly bound to the protein. The secondary structure of undissolved proteins during digestion was mainly β-fold and α-helix. The changes of chemical composition of the bird's nest during digestion process was comprehensively studied in this work, which could provide theoretical support for further development of new bird's nest products with high gastrointestinal digestion characteristics.

Abstract:To monitor the freshness of meat in real time, a pH colorimetric sensitive indicator was prepared by loaded hydroxyanthraquinone derivatives containing carboxyl and methyl groups synthesized by alkylation reaction on a filter paper and then coated with cellulose acetate. It was found that the substituent groups of hydroxyanthraquinone affected pH transition interval. The colorimetric indicator prepared by 1,4-dihydroxy-6-carboxyanthraquinone showed higher sensitive to butane diamine than other indicators. The mobility of the sensitive molecules was reduced by 40.6 % after coated with cellulose acetate, compared with the uncoated group. Placed in a meat package at room temperature after 36 h, the color change of the indicator was visible to the naked eye. This pH colorimetric sensitive indicator could monitor meat freshness conveniently and rapidly.

Abstract:In this study, 56 volatile compounds (VOCs) were identified from the pressed white tea in different years by gas chromatography-ion mobility spectrometry. Principal component analyses (PCA) and linear discriminant analysis(LDA) were used to screen 20 characteristic VOCs. The main VOCs were 2-acetylfuran, heptanal, E-2-octenal, limonene, 2-phenylethanol and isobutyric acid. The contents of limonene, 2-phenylethanol and isobutyric acid were in inverse proportion to the storage time, while the contents of 2-acetyl furan, heptanal and E-2-octenal showed positive correlation. The predictive model equations of storage time (y) and peak intensity response value of main VOCs were established by further regression analysis: y=-0.03x₁+0.038x₂-0.09x₃-0.012x₄+0.002x₅+0.004x₆+0.022x₇+0.019x₈-0.018x₉-0.011x₁₀+0.005x₁₁-0.011x₁₂+0.000x₁₃-0.042x₁₄-0.015x₁₅+0.017x₁₆+0.033x₁₇+0.008x₁₈+0.008x₁₉-0.124x₂₀ (x₁~x₁₃ were the unidentified VOCs, x₁₄~x₂₀ were 2-acetylfuran, limonene, 2-phenylethanol dimer, 2-phenylethanol monomer, 2-heptanone, e-2-octene aldehyde and isobutyric acid), R₂=0.929 and sig<0.05. In addition, the unique flavor characteristics of floral, aromatic herbs and nutty flavors in pressed white tea could be formed by the interaction between the characteristic VOCs of pressed white tea during storage. The storage life of pressed white tea could be scientifically distinguished by GC-IMS and stoichiometry, providing theoretical basis for standardizing the market of pressed white tea.

Abstract:Agrocybe praecox has a unique flavor style. The volatile components in pileus and stipe of Agrocybe praecox were determined by head-space solid phase microextraction combined with gas chromatography-mass spectrometry(HS-SPME-GC-MS). There were 48 and 47 volatile compounds identified from the pileus and stipe of Agrocybe praecox, respectively, 16 of which were the same components, accounting for 20.25% of the volatile components. These compounds were mainly alkanes, ketones, esters and acids, of which decamethylcyclopentasiloxane, 2-methyl-3-heptanone, dihydro-5-pentyl-2(3H)-furanone, 3-hydroxymandelic acid and benzeneacetic acid were the common components of pileus and stipe of Agrocybe praecox with relative high content. The volatile components in the Agrocybe praecox were systematically studied to provide theoretical support for further develop and utilization of the compoundsin Agrocybe praecox.

Abstract:An electrochemical detection method based on microfluidic chip was proposed to improve complex operation, low degree of automation and large reagent-consuming in the tea polyphenols detection. The microfluidic detection platform was established with 3D printed microfluidic chip as the detection channel and screen-printed carbon electrode as the electrochemical sensor. The effects of various buffer solutions, pH values, scan rates and feed rates on the oxidation peak current in cyclic voltammetry detection were studied using gallic acid (GA) as the test standard. This method was then applied to determine the tea polyphenols in samples from Pu'er tea. This method achieved a linear response in the range of 5～1 250 μmol/L GA under the optimal experimental condition. In addition, the detection limit was 6.9×10^-7 mol/L and the recovery rate was between 97.6%and 104.6%.The result was consistent with the Folin-Ciocaulteau method. The detection time decreased to 40 s and the dosage of reagent was 70 μL. The proposed method has the advantage of less sample consumption and shorter detection time. It can be applied to the rapid detection of tea polyphenols.