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Nitrogen application modified the effect of mycorrhization on strawberry fruit quality.

Organic acids of wine, in addition to ethanol, have been identified as stimulants of gastric acid secretion. This study characterized the influence of other wine compounds, particularly phenolic compounds, on proton secretion. Forty wine parameters were determined in four red wines and six white wines, including the contents of organic acids and phenolic compounds. The secretory activity of the wines was determined in a gastric cell culture model (HGT-1 cells) by means of a pH-sensitive fluorescent dye. Red wines stimulated proton secretion more than white wines. Lactic acid and the phenolic compounds syringic acid, catechin, and procyanidin B2 stimulated proton secretion and correlated with the pro-secretory effect of the wines. Addition of the phenolic compounds to the least active white wine sample enhanced its proton secretory effect by 65 ± 21% (p < 0.05). These results indicate that not only malic and lactic acid but also bitter and astringent tasting phenolic compounds in wine contribute to its stimulatory effect on gastric acid secretion.

Red wine is enriched in resveratrol, trans-3,5,4'-trihydroxystilbene, a compound in grape skin that inhibits the development of pre-neoplastic lesions in mouse mammary tumor cells in culture and inhibits cancer cell proliferation in vitro. Grapes also contain other bioactive compounds including flavonoids, flavans, and anthocyanins. The estrogenic activities of extracts prepared from one white (Freie Weingärtner Wachau, Grüner Veltliner, Austria) and two red wines (Woodbridge, Cabernet Sauvignon, California; and Lenz Moser Prestige, Blaufränkisch Barrique, Austria) were examined and compared with those induced by estradiol (E(2)) and trans-resveratrol. First, the estrogenic activity of the wine extracts was evaluated in a yeast estrogen screen (YES) assay, in which yeast express copper-inducible estrogen receptor alpha (ERalpha) and an estrogen-response-element (ERE)-driven beta-galactosidase reporter. In YES, the white wine extract showed no estrogenic activity. In contrast, both of the red wine extracts showed estrogenic activity equivalent to that of 0.2 nM E(2). Similarly, the white wine extract showed no transcriptional activity with either ERalpha and ERbeta in transiently transfected CHO-K1 cells. In contrast, both red wine extracts stimulated ERE-reporter activity in a concentration-dependent manner that was inhibited by 4-hydroxytamoxifen (4-OHT), indicating that the observed transcriptional activity was ER-mediated. The red wine extracts showed significantly higher ERbeta versus ERalpha agonist activity. Resveratrol showed no agonist activity in YES but activated ERalpha and ERbeta in CHO-K1 cells in a concentration-dependent manner that was inhibited by 4-OHT. This indicates that resveratrol requires mammalian cell components that are absent in yeast for estrogen agonist activity, whereas the estrogenic activity of wine extracts is directly through ERalpha and does not require mammalian cell factors such as coactivators. The estrogenic activity in red wine found by using YES indicates that estrogenic compounds other than resveratrol are present. Chemical analysis clearly showed that the trans-resveratrol content of the red wine extracts was 1 order of magnitude below the detection limit for YES assay.

No abstract

Highlights► Glycosidases of Oenococcus oeni are able to release terpenes from natural substrates. ► Bacterial glycosidases have a high capacity to release both primary and tertiary terpene alcohols. ► Both glucosidase and arabinosidase from O. oeni are more active in grape juice than glycosidases from Aspergillus niger. ► Riesling mash was treated with O. oeni glycosidases before alcoholic fermentation. ► Wines produced with the glycosidases from O. oeni received positive ratings by a professional panel.

No abstract

␣-L-Rhamnosidases play an important role in the hydrolysis of glycosylated aroma compounds (especially terpenes) from wine. Although several authors have demonstrated the enological importance of fungal rhamnosidases, the information on bacterial enzymes in this context is still limited. In order to fill this important gap, two putative rhamnosidase genes (ram and ram2) from Pediococcus acidilactici DSM 20284 were heterologously expressed, and the respective gene products were characterized. In combination with a bacterial ␤-glucosidase, both enzymes released the monoterpenes linalool and cis-linalool oxide from a muscat wine extract under ideal conditions. Additionally, Ram could release significant amounts of geraniol and citronellol/ nerol. Nevertheless, the potential enological value of these enzymes is limited by the strong negative effects of acidity and ethanol on the activities of Ram and Ram2. Therefore, a direct application in winemaking seems unlikely. Although both enzymes are members of the same glycosyl hydrolase family (GH 78), our results clearly suggest the distinct functionalities of Ram and Ram2, probably representing two subclasses within GH 78: Ram could efficiently hydrolyze only the synthetic substrate p-nitrophenyl-␣-L-rhamnopyranoside (V max ‫؍‬ 243 U mg ؊1 ). In contrast, Ram2 displayed considerable specificity toward hesperidin (V max ‫؍‬ 34 U mg ؊1 ) and, especially, rutinose (V max ‫؍‬ 1,200 U mg ؊1 ), a disaccharide composed of glucose and rhamnose. Both enzymes were unable to hydrolyze the flavanone glycoside naringin. Interestingly, both enzymes displayed indications of positive substrate cooperativity. This study presents detailed kinetic data on two novel rhamnosidases, which could be relevant for the further study of bacterial glycosidases.␣-L-Rhamnosidases (EC 3.2.1.40) catalyze the hydrolysis of a wide spectrum of natural glycosides containing terminal Lrhamnose. The biotechnological interest in rhamnosidases includes the debittering of citrus fruit juices (naringinase and hesperidinase), the release of flavonoids from rhamnosylated precursors, and the production of L-rhamnose as starting material for chemical synthesis (52). Further, rhamnosidases may play a crucial role in wine making due to their contributions to releasing grape-derived aroma compounds (mainly terpenes and terpenic alcohols). Depending on the grape variety, rutinosides (␣-L-rhamnopyranosyl-␤-D-glucopyranoside) constitute 6 to 13% of the terpenic glycosides found in wine (29). The combination of ␤-D-glucosidase and ␣-L-rhamnosidase allows the sequential release of volatile compounds from these precursors (18). Several authors (9, 32, 46) have demonstrated the enological value of fungal (Aspergillus sp.) rhamnosidases. Based on their adaptation to the harsh wine milieu and their general hydrolytic abilities toward different glycosides (16,17,50), wine-related lactic acid bacteria (LAB) have attracted much interest as a potential source of novel glycosidases (34).Consequently, several (intracellular) glycosid...