In this study, we aimed to explore the effect of anaerobic treatment on the contents and functions of bioactive components such as γ-aminobutyric acid (GABA) in yellow tea and to analyze the mechanism by which anaerobic treatment promotes GABA enrichment using metabolomics. We also analyzed the changes in related metabolism pathways. The results showed that the content of GABA in yellow tea was increased to 3.3 mg/g after anaerobic treatment, and the contents of the upstream and downstream amino acids related to GABA were changed correspondingly. Moreover, anaerobic treatment significantly increased the contents of total phenolics and total flavonoids in yellow tea. In vitro bioactivity evaluation showed that anaerobic treatment improved the free radical scavenging capacity, total antioxidant activity and inhibitory effect on the formation of glycosylation products of yellow tea, but had little effect on the ability of yellow tea to inhibit starch digestion enzymes. A total of 218 differential metabolites between fresh and GABA-rich tea, including amino acids, organic acids, flavonoids, nucleotides, and sugars. Pathway enrichment analysis demonstrated that the amino acid biosynthesis, tryptophan metabolism, flavonoid biosynthesis, and butyrate metabolism pathways were significantly regulated. Anaerobic treatment could regulate the GABA content in yellow tea by affecting the L-glutamate and succinic semialdehyde pathways. This study can provide a reference for the research and development of GABA-rich tea.

At present, the incidence of food allergy is increasing worldwide. Food allergy has become a food safety and public health issue of growing concern. In addition to genetic factors, dietary factors are important factors causing increased risks of food allergy, and the intestinal microbiota plays an important mediating role between diet and the immune system. In view of this, this article systematically reviews recent studies on dietary risk factors for food allergy by summarizing the immunological mechanisms of action of different risk factors and the results of cohort studies and intervention experiments and by providing an in-depth discussion on the role of the intestinal flora in this regard. This review will provide references and new ideas for researchers to develop strategies for the prevention and control of food allergy, as well as understand the mechanism of food allergy using the intestinal microbiota as a target and develop regulatory strategies.

Cutaneous exposure to food allergens through a disrupted skin barrier is recognized as an important cause of food allergy, and the cutaneous sensitized mouse model has been established to investigate relevant allergic disorders. However, the role of different genetic backgrounds of mice on immune responses to food allergens upon epicutaneous sensitization is largely unknown. In this study, two strains of mice, i.e., the BALB/c and C57BL/6 mice, were epicutaneously sensitized with ovalbumin on atopic dermatitis (AD)-like skin lesions, followed by intragastric challenge to induce IgE-mediated food allergy. Allergic outcomes were measured as clinical signs, specific antibodies and cytokines, and immune cell subpopulations, as well as changes in intestinal barrier function and gut microbiota. Results showed that both strains of mice exhibited typical food-allergic symptoms with a Th2-skewed response. The C57BL/6 mice, rather than the BALB/c mice, were fitter for establishing an epicutaneously sensitized model of food allergy since a stronger Th2-biased response and severer disruptions in the intestinal barrier and gut homeostasis were observed. This study provides knowledge for selecting an appropriate mouse model to study food-allergic responses associated with AD-like skin lesions and highlights the role of genetic variations in the immune mechanism underlying pathogenesis of food allergy.