Effects of harvests date and conditions of storage of 'Hayward' kiwifruits on contents of L-ascorbic acid

Abstract

There is a great interest in the nutritional value of food in order to understand the contribution of an individual food product to the daily nutritional needs and harvest time and how preservation technologies affect nutritive composition. Kiwifruit (Actinidia deliciosa) can be considered a highly nutritional product because of its high vitamin C concentration and strong antioxidant capacity. In order to evaluate the effect of harvest maturity stage of 'Hayward' kiwifruit and storage in normal atmosphere (NA) and controlled atmosphere (CA) on L-ascorbic acid (AA) content of kiwifruit was studied. A procedure for the quantitative analyses of AA in Hayward kiwifruit using high performance liquid chromatography (HPLC) was described. For the storage experiment 'Hayward' kiwifruits were harvested at different maturities according to their soluble solids content (SSC) at 4.5-5.5%, 5.6-6.5%, 6.6-7.5% and 8.5-9.5%. Harvested fruit were stored under static CA (5% CO2 + 2% O-2) and NA condition at 0 degrees C and 85-90% relative humidity (RH) for 5 months. AA content of 'Hayward' kiwifruit varied depending on harvest time SSC. Storage conditions and harvest maturity stage according to SSC of kiwifruits affected the AA content changes at 0 degrees C during 5 month storage. In general NA stored fruit had a higher content of AA compared fruits under CA storage. NA storage suppressed degradation of AA content during five months in NA. In contrast, CA storage reduced AA, especially in early harvested fruits, more than in late harvested fruits. All results showed that harvest maturity according to SSC of 'Hayward' kiwifruits and storage conditions had an important effect on the AA content during storage. These results suggest that the best harvest maturity of 'Hayward' kiwifruit for long-term storage is the third or fourth period (6.6-7.5% and 8.5-9.5%, SSC content) and NA storage is better to conserve AA content during long storage.