title: Berry ripening, pre-processing and thermal treatments affect the phenolic composition and antioxidant capacity of grape (Vitis vinifera L.) juice.
abstract: BACKGROUND
  Grape juice is an important dietary source of health-promoting antioxidant molecules. Different factors may affect juice composition and nutraceutical properties. The effects of some of these factors (harvest time, pre-processing ethylene treatment of grapes and juice thermal pasteurization) were here evaluated, considering in particular the phenolic composition and antioxidant capacity.
  
  
  RESULTS
  Grapes (Vitis vinifera L., red-skinned variety Sangiovese) were collected twice in relation to the technological harvest (TH) and 12 days before TH (early harvest, EH) and treated with gaseous ethylene (1000 ppm) or air for 48 h. Fresh and pasteurized (78 °C for 30 min) juices were produced using a water bath. Three-way analysis of variance showed that the harvest date had the strongest impact on total polyphenols, hydroxycinnamates, flavonols, and especially on total flavonoids. Pre-processing ethylene treatment significantly increased the proanthocyanidin, anthocyanin and flavan-3-ol content in the juices. Pasteurization induced a significant increase in anthocyanin concentration. Antioxidant capacity was enhanced by ethylene treatment and pasteurization in juices from both TH and EH grapes.
  
  
  CONCLUSIONS
  These results suggest that an appropriate management of grape harvesting date, postharvest and processing may lead to an improvement in nutraceutical quality of juices. Further research is needed to study the effect of the investigated factors on juice organoleptic properties.
authors: Institute of Life Sciences, Scuola Superiore Sant'Anna, 56127, Pisa, Italy.
authors: Giuseppe
authors: G
authors: Genova
authors: Institute of Life Sciences, Scuola Superiore Sant'Anna, 56127, Pisa, Italy.
authors: Roberta
authors: R
authors: Tosetti
authors: Institute of Life Sciences, Scuola Superiore Sant'Anna, 56127, Pisa, Italy.
authors: Pietro
authors: P
authors: Tonutti
mesh_terms: D000975:Antioxidants / Q000032:analysis*; D001628:Beverages / Q000032:analysis*; D003373:Coumaric Acids / Q000032:analysis; D019587:Dietary Supplements; D005030:Ethylenes / Q000494:pharmacology; D005419:Flavonoids / Q000032:analysis; D005511:Food Handling / Q000379:methods; D005638:Fruit / Q000254:growth & development*; D006358:Hot Temperature; D061352:Pasteurization; D010636:Phenols / Q000032:analysis*; D059808:Polyphenols / Q000032:analysis; D027843:Vitis
chemical_list: D000975:Antioxidants; D003373:Coumaric Acids; D005030:Ethylenes; D005419:Flavonoids; D010636:Phenols; D059808:Polyphenols; C036216:ethylene
keywords: grape berries; harvest time; juice pasteurization; phenol compounds; postharvest ethylene; ripening stage