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Ara h 1 is one of the major allergens existed in peanut, peptides formed in the digestion process of Ara h 1 could induce allergic symptoms and cause local inflammatory. The mechanism of intestine epithelial immune has not been clarified yet. Here we explored the effect of digestion on the immunoreactivity and proinflammatory properties of recombinant Ara h 1 (rAra h 1). rAra h 1 was treated (or untreated) with heat, digested by pepsin. According to the results, in the early period of digestion, both native and heated rAra h 1 were degraded. Q-PCR and Western-blot results revealed that the NF-κB pathway was involved in the cytokine secretion. The proinflammatory effect were less pronounced in the samples treated with heat, demonstrating that digestion, instead of thermal process, could modify the proteins and peptides, which could then play a significant role in the activation of Caco-2 cells via the NF-κB pathway. [ABSTRACT FROM AUTHOR]

Food processing affects the bioavailability and immunoreactivity of allergens. However, there was a lack of the combined study of the influence of the processing and gastrointestinal digestion on peanut matrix. Digestibility of peanut matrices was assessed by using an in vitro digestion model and monitored by SDS-PAGE, immunoblotting with polyclonal antibody and serum from peanut-allergic patients. The IgE-binding ability of digested samples will be assessed by immunoassay. Peanut proteins were digested by pepsin after only 2 min which was accompanied by a loss of high molecular weight proteins and enrichment in polypeptides with molecular weight lower than 10 kDa. Ara h 1 and Ara h 3 were partly proteolysis, and Ara h 2/6 containing a digestion-resistant fragment. All soluble fractions after 120 min gastric digestion reduced a higher IgE-binding ability than that after 10 min. Our findings provide a more realistic picture, considering the role of food processing and food matrix. [ABSTRACT FROM AUTHOR]

Ara h 1 is a key peanut allergen and its activity is significantly affected by protein intrinsic structure which is found to be regulated by heat treatment, although the molecular basis for this regulation has remained largely unknown. Here, we explored the effect of boiling on the structure and allergenicity of recombinant peanut protein Ara h 1 (rAra h 1). rAra h 1 was purified from E. Coli BL21(DE3) plysS cells and structurally studied. According to the results, rAra h 1 undergoes degradation during the heating process, and the aggregation of fragments happened after 20 min of heating. An increased surface hydrophobic index and a decreased content of α-helixes were found in rAra h 1, indicating a looser protein structure of rAra h 1 caused by heat treatment. Destroyed epitopes during protein degradation and aggregation could be a mechanism of reducing the allergenic nature of rAra h 1 by heat treatment. [ABSTRACT FROM AUTHOR]

A novel method for the determination of five carbamate pesticides (metolcarb, carbofuran, carbaryl, isoprocard and diethofencard) in watermelon and tomato samples was developed by dispersive liquid–liquid microextraction (DLLME) coupled with high performance liquid chromatography-diode array detection (HPLC-DAD). Some experimental parameters that influence the extraction efficiency were studied and optimised to obtain the best extraction results. Under the optimum conditions for the method, the calibration curve was linear in the concentration range from 10 to 1000 ng g−1 for all the five carbamate pesticides, with the correlation coefficients (r) varying from 0.9982 to 0.9992. Good enrichment factors were achieved ranging between 80 and 177, depending on the compound. The limits of detection (LODs) (S/N = 3) were ranged from 0.5 to 1.5 ng g−1. The method has been successfully applied to the analysis of the pesticide residues in watermelon and tomato samples. The recoveries of the method fell in the range between 76.2% to 94.5% with RSDs less than 9.6%, indicating the feasibility of the DLLME method for the determination of the five carbamate pesticides in watermelon and tomato samples. [ABSTRACT FROM AUTHOR]