Changes in the content and antioxidative activity of β-carotene and its metabolite vitamin A during gastrointestinal digestion and absorption and optimisation of HPLC-based detection

The β-Carotene (BC), an important precursor of vitamin A (VA), possesses antioxidant activity but is fat-soluble and has low bioavailability. In previous in-vitro assays evaluating antioxidant and 2,2′-azobis(2-amidinopropane) dihydrochloride (AAPH) free radical scavenging, both BC and VA showed a strong ability to scavenge radicals and protected cells from oxidative stress. Here, we used artificially simulated gastrointestinal digestion and Caco-2 cell absorption models to evaluate the bioavailability of the BC during gastrointestinal digestion and absorption using high-performance liquid chromatography (HPLC) analysis. We observed high absorptive and transfer rates of BC and detected retinol metabolites (Vitamin A). Therefore, BC can be detected in the acidic gastrointestinal environment using HPLC. Optimised method provided better separation of BC and VA in the column, improving the accuracy of the test results.     

Profiles and concentrations of heterocyclic aromatic amines formed in beef during various heat treatments depend on the time of ripening and muscle type

Heterocyclic Aromatic Amine (HAA) profiles and concentrations depended on several factors. The largest changes in the HAA profile were observed in meat ripened (chill stored) for 5–10 days. Amines whos concentration varied most prominently included: Phe-P 1, harmane, AαC, IQ, IQx, PhIP, MeAαC, and MeIQx. HAA concentrations were strongly correlated with concentrations of the above compounds. Time of storage significantly affected the HAA profile and concentration. The profile changed dynamically for storage times up to 10 days. For longer times the profile stabilized, only the HAA content increased.A novel, highly precise and accurate HAA analytical method was developed for this study. Results may help to optimize meat processing technology from the point of view of reducing concentration of HAA formed during heat treatment, including the most carcinogenic; IQ, IQx, MeIQx and PhIP amines.     

兜唇石斛发酵多肽Asp-Asp-Asp-Tyr和Asp-Tyr- Asp-Asp对LPS诱导RAW264.7细胞的抗炎作用

为了研究兜唇石斛发酵多肽Asp-Asp-Asp-Tyr（DDDY）、Asp-Tyr-Asp-Asp（DYDD）对LPS诱导的RAW264.7巨噬细胞抗炎活性。以合成的兜唇石斛发酵多肽为研究对象,采用噻唑蓝法筛选增殖活性最高的发酵多肽浓度,通过中性红吞噬实验和倒置显微镜观察发酵多肽对细胞的吞噬作用和分化形态变化,使用ELISA试剂盒测定细胞中NO及细胞因子IL-1β、IL-6、IL-10和肿瘤坏死因子TNF-α的分泌量。结果表明：12.5、25、50和100 μg/mL四组质量浓度的发酵多肽对细胞无毒性并有增殖作用;100 μg/mL的DDDY和DYDD和1 μg/mL的LPS处理可以激活细胞,增强细胞吞噬能力,相对吞噬率为2.05%、1.97%和2.19%;构建LPS诱导的RAW264.7细胞炎症模型,发现两种发酵多肽处理有效抑制细胞分化,使细胞恢复正常形态;抑制细胞NO分泌能力,100 μg/mL DDDY和DYDD处理组的NO分泌能力降低到LPS组的0.41倍和0.49倍;并且对抑炎细胞因子分泌能力的提高和促炎细胞因子的降低有显著效果,均表现出剂量反应关系。由此可知,DDDY和DYDD对LPS诱导的RAW264.7巨噬细胞炎症反应具有抗炎作用,为后面探究发酵多肽的炎症机制提供理论支持。     

Changes in polyphenol fractions and bacterial composition after in vitrofermentation of apple peel polyphenol by gut microbiota

The changes in polyphenol fractions after in vitro fermentation of apple peel polyphenol (APP) by gut microbiota as well as the effects of APP on the growth, pH value, short-chain fatty acids (SCFAs) production and intestinal flora composition of gut microbiota fermentation were firstly explored in this study. The relative abundance of Lactobacillus in the APP group was 49.55% with an increment of 49.40% compared with the blank group, while that of Bifidobacterium was 13.32%. Moreover, the flora produced 37.093 ± 0.478 mM of SCFAs including acetic acid, propionic acid, butyric acid and valeric acid during the process of fermentation, thus reduced the environmental pH value. In addition, polyphenol fractions in APP were altered by gut microbiota fermentation to some extent, for example, glycosides were hydrolysed to aglycones. These findings suggested APP as a potential prebiotic agent to alleviate the disorder of intestinal flora.     

Effects of methyl cellulose-based coating on physiochemical properties and chemical hazards of Chinese fried dough cake during storage

Coating has been used as a practical method to ensure the physiochemical properties and reduce the chemical hazard of fried foods. Methyl cellulose (MC) was used as a coating material to pretreat Chinese fried dough cake (CFDC) before frying. The results showed that the water content, hardness and L* value of the 1% MC coated sample were 31.67%, 848.54 g and 51.62, respectively, at the seventh day at 25 °C. Coating contents 1% MC could reduce the oil content, hardness, and extent of browning and improve the physiochemical properties of CFDC on 7 days of storage. Coating contents 1% MC also reduced the acid value, peroxide value, p-anisidine value, malondialdehyde content, 4-hydroxy-2-(E)-hexenal content, 4-hydroxy-2-(E)-nonenal content, acrylamide content and glycidyl ester content in CFDC on 7 days of storage. Our work contributes to the control of the oil content and chemical hazards for fried food during storage by applying an edible coating.     

Formation of malondialdehyde, 4-hydroxy-hexenal and 4-hydroxy-nonenal during deep-frying of potato sticks and chicken breast meat in vegetable oils

The present work investigated the formation of three toxic aldehydes, malondialdehyde (MDA), 4-hydroxy-hexenal (HHE) and 4-hydroxy-nonenal (HNE), during deep-frying of different foods in corn oil (CO), rapeseed oil (RO) and linseed oil (LO). Besides, their contents in French fries (FF) and fried chicken breast meat (FCBM) were also explored. Results showed that the MDA/HHE/HNE levels in frying groups were all lower than those in control, indicating the incorporation into the fried foods. Apart from the different levels, MDA/HHE/HNE in FF and FCBM possessed similar variation tendencies, revealing the matrix-mediated distribution. The combined exposure assessment based on the threshold of toxicological concern (TTC) levels was conducted, and risks of exceeding the limitation values (1.5 μg kg bw⁻¹ day⁻¹) for HNE in CO and HHE in LO were exhibited. The consumption of both FF and FCBM should be regulated, considering the levels of MDA, HHE and HNE these fried foods may contain.     

HPLC–MS validation of QualisaFoo® biosensor kit for cost-effective control of acrylamide levels in Italian coffee

Acrylamide is a carcinogenic and mutagenic compound found in many industrially processed foods and beverages, including coffee. The aim of this work is to determine the acrylamide level in some Italian coffees by using a mass spectrometry method and an enzymatic test kit. Comparison of average values in four Italian coffees determined using the two methods permitted us to validate the results obtained with the kit, hence the kit itself, showing that acrylamide is present in low amount.The amount of acrylamide was also determined in other foods, by using the kit. This work shows that there is a correspondence between the two methods and that the kit provides a cost-effective method to determine the amount of acrylamide in food.     

Role of lipid deterioration on the quality of aquatic products during low-temperature storage: a lipidomics-based study using large yellow croaker (Larimichthys crocea)

This work investigated the effects of different storage periods (0 day, 90 days, 120 days) on the quality of large yellow croaker oil. The lipomics of large yellow croaker oil was quantitatively detected by GC-MS, the content of triglyceride in large yellow croaker oil reached 52.56% at 0 day. With the extension of storage time, the content of large yellow croaker oil components decreased gradually. Differential lipid histogram clearly indicates that the extension of the storage period will affect the change of fish oil, due to the rise in the temperature of large yellow croaker oil; the color of the hot map is bright from the dark. Additionally, the fatty acid composition and volatile components were measured. At 120 days, the decomposition rate of lipid molecular in large yellow croaker oil is increased by oxidation of unsaturated fatty acids, and its oxidised metabolite produced small substance such as aldehydes, ketones, alcohols, and acids. During storage, the waxy, fat, and floral flavour in the oil aroma of large yellow croaker oil decreased gradually, while the yeast flavour and oil flavour increased gradually. These results provide insights for the study of lipid transformation and quality of large yellow croaker oil during different storage.     

白酒酿造中杂醇油调控技术的研究进展

白酒承载了中国特色文化,其品质与酒中的风味物质密切相关。在白酒酿造过程中,杂醇油的生成是必然的。适量的杂醇油会使酒体更为协调;过多的杂醇油会引起酒后“上头”,给饮用舒适感带来一定影响。该文概括了酿酒酵母中杂醇油的形成机制,总结了白酒酿造过程中杂醇油控制技术的研究进展,为白酒发酵过程中杂醇油控制技术体系的建立提供借鉴。