Temperature and water loss affect ADH activity and gene expression in grape berry during postharvest dehydration.

Abstract

Clusters of Aleatico wine grape were picked at 18°Brix and placed at 10, 20, or 30°C, 45% relative humidity (RH) and 1.5m/s of air flow to dehydrate the berries up to 40% of loss of initial fresh weight. Sampling was done at 0%, 10%, 20%, 30%, and 40% weight loss (wl). ADH (alcohol dehydrogenase) gene expression, enzyme activity, and related metabolites were analysed. At 10°C, acetaldehyde increased rapidly and then declined, while ethanol continued to rise. At 20°C, acetaldehyde and ethanol increased significantly with the same pattern and declined at 40%wl. At 30°C, acetaldehyde did not increase but ethanol increased rapidly already at 10%wl. At the latter temperature, a significant increase in acetic acid and ethyl acetate occurred, while at 10°C their values were low. At 30°C, the ADH activity (ethanol to acetaldehyde direction), increased rapidly but acetaldehyde did not rise because of its oxidation to acetic acid, which increased together with ethyl acetate. At 10°C, the ADH activity increased at 20%wl and continued to rise even at 40%wl, meaning that ethanol oxidation was delayed. At 20°C, the behaviour was intermediate to the other temperatures. The relative expression of the VvAdh2 gene was the highest at 10°C already at 10%wl in a synchrony with the ADH activity, indicating a rapid response likely due to low temperature. The expression subsequently declined. At 20 and 30°C, the expression was lower and increased slightly during dehydration in combination with the ADH activity. This imbalance between gene expression and ADH activity at 10°C, as well as the unexpected expression of the carotenoid cleavage dioxygenase 1 (CCD1) gene, opens the discussion on the stress sensitivity and transcription event during postharvest dehydration, and the importance of carefully monitoring temperature during dehydration.

• Authors: Marco Cirilli, Andrea Bellincontro, Diana De Santis, Rinaldo Botondi, Maria Chiara Colao, Rosario Muleo, Fabio Mencarelli
• Journal: Food chemistry (Food Chem) Vol. 132 Issue 1 Pg. 447-54 (May 01 2012) ISSN: 1873-7072 [Electronic] England
• PMID: 26434314 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: Copyright © 2011 Elsevier Ltd. All rights reserved.

Chemical References

• Water
• Ethanol
• Alcohol Dehydrogenase
• Acetaldehyde
• Acetic Acid

Topics

• Acetaldehyde (analysis)
• Acetic Acid (analysis)
• Alcohol Dehydrogenase (genetics, metabolism)
• Desiccation (methods)
• Ethanol (analysis)
• Food Handling (methods)
• Fruit (chemistry, enzymology)
• Gene Expression
• Oxidation-Reduction
• Temperature
• Vitis
• Water (analysis)