Effects of new packaging solutions on physico-chemical, nutritional and aromatic characteristics of red raspberries (Rubus idaeus L.) in postharvest storage

Abstract

Postharvest life of raspberries (Rubus idaeus L.) is limited due to their high respiration rate, loss of firmness and freshness and susceptibility to fruit rot. The aim of this research was to evaluate the effects of various packaging solutions on physico-chemical, nutritional and aromatic properties of raspberries during storage at +4°C up to 7 days. Plastic materials with low (LDPE) and high (LDPE/EVOH/LDPE) gas barrier, a biopolymeric film (PLA) with medium gas barrier and micro perforated stretch film (PVC) were used. The packaging material modified the composition of the atmosphere in the package, which depended on the combined action of the respiration activity of the fruit and the permeability of the material. Results showed that the most sensitive parameters for the assessment of raspberry decay were percentage of damaged berries, weight loss, fruit softening and the aromatic profile development, evaluated by an electronic nose; these parameters showed significant changes during storage and were influenced by the packing material. All samples showed a clear loss of firmness after 4 days of storage, which was maximally reduced in the case of LDPE/EVOH/LDPE and PLA packages. Raspberries stored in PVC packaging material had an aromatic development similar to the control, whereas berries stored in the medium and high barrier materials showed important changes in the aromatic profile, reflecting anaerobic metabolism of fruit. Soluble solids, pH, total phenolics and ascorbic acid did not change significantly; changes in colour and total anthocyanins were observed, with differences depending on the kind of packaging.