Influences of ripening stage on quality index in apricot for fresh market and processing

In this study the influence of maturity stage on chemical and physical parameters of fresh and processed apricot fruits (Prunus armeniaca L. cv. 'Portici') was investigated. Apricots were harvested at two commercial maturity stages respectively characterised by an average penetrometer reading of 8 and 10. 8 Kg/cm(2) and a soluble solids content of 13.6 and 11.9 Brix degrees. Fruits were stored at 20 degrees C and 70% RH. Soluble solids, polygalacturonase and carotenoid content increased during the apricot storage. A SDS-PAGE assay involving a specific staining of polygalacturonic acid was used to determine polygalacturonase activity. Fruit firmness decreased during the storage and a linear relationship was found with the polygalacturonase activity. An in vitro assay was used to determine the carotenoid bioavailability. This parameter increased with the carotenoid concentration and was correlated to fruit softening and polygalacturonase activity. Apricots were processed for puree production, yields increased with the maturity stage as well as the puree carotenoid content and bioavailability. The use of an enzymatic mixture during processing increased puree yields for both maturity stages. Enzyme treatment also improved the carotenoid content and bioavailability in the puree obtained from apricots at the higher maturity stage.