Cultivated strawberry (Fragaria × ananassa) is a fruity vegetable of the Rosaease family and contains allergens which cause oral allergic syndrome (OAS). OAS is a type I allergy mediated by IgE, and as the symptoms appear in the oral cavity, hypoallergenic fruits are eagerly anticipated. The major allergen in strawberry OAS is Fra a 1—an ortholog of the birch pollen allergen Bet v 1. It is necessary to understand the characteristics of Fra a 1 in planta to properly regulate Fra a 1 accumulation and produce safe edible fruits. In this review, we summarize the Fra a 1 expression patterns in strawberries and this allergenicity in birch patients’ IgE. Additionally, we describe the cultivar differences and environmental responses of Fra a 1 and discuss the proper regulation of Fra a 1 in order to produce hypoallergenic fruits.

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Isothiocyanates (ITCs) are organosulfur compounds derived from cruciferous plants. An electrophilic ITC group (-N=C=S) reacts with some functional groups such as a hydroxyl ion, a thiol group and amine groups in proteins. It is known that ITCs are decomposed easily by the addition of a hydroxyl ion to the ITC group in aqueous solutions. In the intracellular behavior, the primary target of ITCs is a thiol group, which results in the formation of their dithiocarbamate conjugates. The reaction is considered to induce the health promoting and disease preventive effects of ITCs. ITCs also react with amine groups to form stable thioureas. This review offers a short summary of the stability and reactivity of ITCs and the plausible behavior of their dithiocarbamate- and thiourea-conjugates.

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Mulberry fruit is thought as a healthy sweetener because it contains iminosugars, such as 1-deoxynojirimycin (1-DNJ), fagomine and 2-O-α-D-galactopyranosyl deoxynojirimycin (GAL-DNJ), that inhibits α-glucosidase. In this study, we quantified iminosugars and glucose concentrations in Morus australis fruit foods and analyzed their inhibitory effects against the activities of α-glucosidase-related four enzymes, maltase, glucoamylase, sucrase, and isomaltase. By LC-MS/MS, the concentrations of 1-DNJ, fagomine, and GAL-DNJ of the M. australis fruit wine, juice, vinegar drink, vinegar, and jam were 1.76–32.5, 0.058–0.290, and 30.2–209 μg/mL, respectively. By high-performance anion-exchange chromatography with pulsed amperometric detection (HPAE-PAD), the glucose concentrations were 0 mg/mL for wine and 13.9–39.7 mg/mL for juice, vinegar drink, vinegar, and jam. The IC50 values of these five foods were 1.9–4.4 % v/v for maltase, 0.37-5.0 % for glucoamylase, and 0.28–1.2 % for sucrase, and 2.0% for isomaltase. Considering the 1-DNJ and glucose concentrations in these five M. australis fruit foods and the IC50 values of 1-DNJ and glucose for α-glucosidase, it was suggested that 1-DNJ is a main inhibitor for α-glucosidase in these foods, and glucose is involved in the inhibition except for wine.

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