RT Journal Article
SR Electronic
T1 Effect of Reductive Pressing on the Content of Reduced Glutathione and Phenols in the Musts of Four Italian Cultivars
JF American Journal of Enology and Viticulture
JO Am. J. Enol. Vitic.
FD American Society for Enology and Viticulture
SP ajev.2014.13087
DO 10.5344/ajev.2014.13087
A1 Silvia Motta
A1 Massimo Guaita
A1 Maurizio Petrozziello
A1 Loretta Panero
A1 Antonella Bosso
YR 2014
UL http://www.ajevonline.org/content/early/2014/07/16/ajev.2014.13087.abstract
AB This research investigated the effect of pressing conditions (under air or nitrogen) on the color parameters and content of reduced glutathione (GSH), hydroxycinnamyl tartaric acids (HCTA) and polyphenols in the musts of four Italian white grape cultivars (Arneis, Cortese, Moscato bianco and Manzoni bianco). Grapes from different locations were pressed using a prototype press (500 kg capacity) under the same operating conditions of a commercial winery. The musts of the four cultivars were significantly different from one another according to the parameters observed. The trend of the measured GSH content in the musts was as follows: Moscato bianco < Cortese < Manzoni bianco < Arneis, without any significant interactions between cultivar and year. The intake of oxygen during pressing in air caused large decreases in GSH concentration, yet its complete exhaustion was only observed in a few trials. When present, the residual GSH content proved to be in proportion to the values observed in the respective trials pressed under nitrogen. The contact with air during pressing also lowered the amount of total polyphenols and catechins. The loss of catechins did not depend on the composition of musts in HCTA, GSH and HCTA/GSH, while color browning was influenced by the HCTA/GSH molar ratio. The color intensity of musts (A420) increased exponentially with the decrease of GSH content: A420 values higher than 0.2 u.a. were observed for GSH contents lower than 8 μM.