Storage Performance of University of Arkansas Peach and Nectarine Genotypes Harvested At Different Maturities and Subjected to Pre-Storage Treatments

The University of Arkansas peach breeding program focuses on diverse flesh types in peaches and nectarines. Breeding has led to firm-melting and non-melting genotypes that are firm when well-mature, intended to allow for fruit to be picked at a higher quality state than melting-flesh genotypes. However, no postharvest evaluations have been conducted. Fruit from 30 genotypes with flesh types including non-melting, standard-melting, and firm-melting were sampled. Genotypes also varied for low- to standard-acid flavor, pit adherence, soluble solids content (SSC), and flesh color. Fruits were harvested at two maturity stages, minimum maturity (commercial ripe) and well-mature (tree ripe). After harvest, fruit were conditioned for 24 hours at ~20 °C and then exposed to 2 min of ~1 °C hydro-cooling with 100 ppm chlorine, a 2 min hot water dip at ~50 °C, or rinsed with ~20 °C water. Fruit were then stored at ~1 °C for 4 weeks and sampled weekly.  Prior to evaluation, fruit were warmed at ~20 °C for 24 hours. SSC, pH, skin quality and color, flesh color, flavor, and flesh browning were evaluated. A three-way interaction for maturity, genotype, and storage length was found for the variables. After 4 weeks of cold storage, both melting and non-melting fruit harvested at the well-mature level showed greater reductions in flesh and skin color quality, skin condition, and taste, and had more flesh browning than fruit harvested at minimum maturity. The standard melting, white genotypes picked at the well-mature level had poorer flesh and skin color, skin condition, and taste compared to standard yellow melting genotypes picked at the same well-mature stage. This trend was not found in the firm-melting or non-melting types. After 2 weeks of storage, the melting genotypes showed higher levels of flesh browning and diminished flesh and skin color, quality, and taste over non-melting types. The firm-melting genotypes had improved skin quality, skin color, and taste after 2 weeks of storage and maintained higher skin quality with reduced incidences of flesh browning after 4 weeks compared to melting types. After 4 weeks of cold storage, the firm-melting genotypes had the least browning of all types and the non-melting genotypes had superior skin quality and skin and flesh color over all other types. SSC differences were not observed. The pH of 67% of the genotypes increased during 4 weeks of storage. No significant difference was observed in storage performance among pre-storage treatments.