Influence of Cold Storage on Quality of Croatian Traditional Apple Cultivars

Abstract

The aim of this work was to investigate the influence of cold storage at 2 °C for 180 days on water content, total acids, reducing and total sugar, antioxidant activity, polyphenol oxidase activity, and polyphenol profile of three Croatian traditional apple cultivars ('Kanadska Reneta', 'Ilzer Rosenapfel', 'Wagener'). A significant variation in polyphenol profile of apple cultivars under investigation was noted. The most represented polyphenols in all apple cultivars were procyanidin B2 followed by chlorogenic acid, epigallocatechin, epicatechin, and phloridzin. After storage, the content of procyanidin B2 and chlorogenic acid was higher, while content of epigallocatechin after storage was lower in all investigated apple cultivars. Water content before storage ranged between 79.17 and 80.76 %, and after storage between 75.62 and 78.56 %. Total acids, polyphenol oxidase activity, and flavonoids had decreased during storage, while reducing and total sugar content was higher after storage. Moreover, after storage, cultivar 'Kanadska Reneta' had the highest antioxidant activity measured by both ABTS and DPPH methods, 1.65 and 0.70 mmol trolox kg −1 , respectively. A significant variation in polyphenol profile of apple cultivars under investigation was noted. The most represented polyphenols in all apple cultivars were procyanidin B2, followed by chlorogenic acid, epigallocatechin, epicatechin, and phloridzin. After storage, the content of procyanidin B2 and chlorogenic acid was higher, while content of epigallocatechin after storage was lower in all investigated apple cultivars. Overall, it can be concluded that investigated apple cultivars, after storage, preserved most of the antioxidants and functional properties.

Influence of Polyphenols on the Resistance of Traditional and Conventional Apple Varieties to Infection by Penicillium expansum during Cold Storage

“…The stability of polyphenols depends on various parameters such as temperature, metal ions, proteins, enzymes, oxygen, pH, light or interactions with other food components. The result of decreasing stability is a change in the structures and a decrease in the biological activities of the polyphenols [30,31]. The basis for maintaining the stability of the polyphenols and the quality of the fruit during storage is the reduction of the storage temperature, which increases the shelf life and maintains the quality of the apple [30].…”