INFLUENCE OF THE STORAGE TIME AND PACKAGING MATERIAL ON THE NUTRITION QUALITY OF GRAPE JUICE IN TERM OF ANTIOXIDANT CAPACITY AND PHENOLS CONTENT

Nowadays, consumers are more and more interested in healthy food and technologies with low environmental impact. Grape is a widespread fruit widly used in juice industries and it is reported to contain a variety of phenolic compounds with antioxidant and anti-inflammatory properties, including anthocyanins, tannins, flavonoids and phenolic acids. The wine company "Cascina Belmonte" fully reflects the consumer demand by adopting the organic production protocol for grape juice production. Moreover, in order to preserve color, flavor and nutritional values, including anti-oxidative components and properties, the company has stabilized the grape juice with a high hydrostatic pressure (HHP) treatment, replacing the traditional pasteurization. Besides, a PLA (polylactic acid) bottle for grape juice was tested as a substitute for the PET packaging. The Polylactic acid (PLA) is a biopolymer easily available, not expensive, biodegradable and it is produced with low environmental impact techniques. The aim of this work is the evaluation of the storage stability of organic grape juice during four months of shelf life at 4 °C. The analysis of fruit juice stability is of certain interest not only for the juice production but also for the development of the best materials for packaging. Therefore, antioxidative capacity and concentrations of juice polyphenols are determined in order to provide useful information concerning product storage stability. The results show a general increase of the phenols content after HHP treatment and a loss of most of the phenol compounds during shelf-life, mainly in samples packaged with PLA.