Browning is one of the most common postharvest changes in button mushrooms, which often results in economic losses. Phenolic compounds, which are associated with browning, were extracted from the nonbruised and bruised skin tissue of various button mushrooms with a sulfite-containing solution and analyzed with UHPLC-PDA-MS. In total, 34 phenolic compounds were detected. Only small differences in the total phenolic content between bruising-tolerant and -sensitive strains were observed. The contents of γ-L-glutaminyl-4-hydroxybenzene (GHB) and γ-L-glutaminyl-3,4-dihydroxybenzene (GDHB) correlated with bruising sensitivity; for example, R(2) values of 0.85 and 0.98 were found for nonbruised brown strains, respectively. In nonbruised skin tissue of the strains with brown caps, the GHB and GDHB contents in sensitive strains were on average 20 and 15 times higher, respectively, than in tolerant strains. GHB and GDHB likely participate in the formation of brown GHB-melanin, which seemed to be the predominant pathway in bruising-related discoloration of button mushrooms.

The human sweet taste receptor is a heterodimer comprised of the class C G protein‐coupled receptor (GPCR) subunits TAS1R2 and TAS1R3. A wide collection of sweet tasting compounds and modulators of sweet taste interact with this receptor. Although TAS1R2/TAS1R3‐mediated signaling is well‐studied, the molecular basis for its desensitization remains unclear while such knowledge would signify a profound step forward in understanding the mechanism behind sweet taste perception and taste modulation. In this work, the possible involvement of β‐arrestin in downstream signaling was investigated. A stable clonal Human Embryonic Kidney (HEK)‐derived cell line containing the PathHunter™ GPCR technology was developed, in which β‐arrestin‐mediated endosomal receptor internalization can be monitored by ligand‐induced enzyme complementation of β‐galactosidase (β‐gal). Stimulatory responses and antibody‐specific receptor detection indicated that the TAS1R2/TAS1R3 receptor is endogenously expressed in this clonal cell line. Natural sugars (including fructose, glucose, sucrose, maltose, maltitol and mannitol) and artificial sweeteners (acesulfame‐K and sucralose) stimulated enzyme complementation activity in a concentration dependent manner. Besides, we observed that the assay detected modification of sugar induced cell responses by sweetness enhancers. These results combined implicate that TAS1R2/TAS1R3 receptor desensitization by internalization is most likely mediated by β‐arrestin‐induced endocytosis. This assay approach, making use of naturally expressed TAS1R2/TAS1R3 receptors and required co‐factors, further allows effective screening for and development of novel high potency non‐caloric sweeteners, sweet taste modulators or optimal blends with enhanced sweet taste.

Approximately 70% of birch pollen allergic patients in Europe experience hypersensitivity reactions to Immunoglobulin E (IgE) cross-reactive food sources. This so-called pollen-food syndrome (PFS) is defined by allergic symptoms elicited promptly by the ingestion of fruits, nuts, or vegetables in these patients. So far, in the literature, less attention has been given to Bet v 1 cross-reactive symptoms caused by pear (Pyrus communis). In the Netherlands, pears are widely consumed. The primary objective of this study was to measure the type and severity of allergic symptoms during pear challenges in birch pollen allergic patients, with a positive history of pear allergy, using two different pear varieties. Fifteen patients were included, skin prick test (SPT), prick-to-prick test (PTP), specific Immunoglobulin E (sIgE), and single-blind oral challenges were performed with two pear (Pyrus communis) varieties: the ‘Cepuna’ (brand name Migo®) and the ‘Conference’ pears. All patients were sensitized to one or both pear varieties. A total of 12 out of 15 participants developed symptoms during the ‘Cepuna’ food challenge and 14/15 reacted during the ‘Conference’ challenge. Challenges with the ‘Cepuna’ pears resulted in less objective symptoms (n = 2) in comparison with challenges with ‘Conference’ pears (n = 7). Although we did not find significance between both varieties in our study, we found a high likelihood of fewer and less severe symptoms during the ‘Cepuna’ challenges. Consequently selected pear sensitized patients can try to consume small doses of the ‘Cepuna’ pear outside the birch pollen season.