Optimal Harvest Maturity for Melting and Non-Melting Flesh Subtropical Peach Varieties Ripened Immediately After Harvest or Following Storage

Traditional melting-flesh (MF) peaches ripen and soften quickly at ambient temperature. Thus they have to be harvested at the “firm-ripe” stage, which minimizes mechanical injuries but compromises flavor. Non-melting flesh (NMF) peach fruit potentially have a longer postharvest life since they soften gradually and thus retain texture longer after harvest. The optimum harvest maturity stage is unclear for peach fruit that will be ripened following different storage conditions. A two year study was conducted to identify the optimal harvest maturity of subtropical peach varieties based on quality characteristics determined after immediate ripening and ripening after 2 weeks of refrigerated storage. Two MF cultivars, ‘Tropic Beauty’ and ‘Flordaprince’, and two NMF cultivars, ‘UFSun’ and ‘Gulfking’, were harvested three times during the season. For each harvest, a 50-fruit sample was sorted according to ground color and fruit diameter, assuming that the sampled peaches accurately represented the maturity distribution in the true population; fruit firmness and flesh color (FC) were measured at harvest on 10-fruit samples. The remaining fruit were divided into two groups of 20 for two storage treatments. The first group was ripened at 20 °C for 5 days (S1) and the second group was stored at 0 °C for 14 days, and then ripened at 20 °C for 5 days (S2). Ripe fruit were analyzed for peel ground color (GC) and blush color, FC, flesh firmness, soluble solids content (SSC), total sugars (TS), titratable acidity (TA), pH, and weight loss. In both seasons, MF peaches lost more than 90% of their initial firmness in both storage treatments, whereas NMF fruit lost around 50%.  For both MF and NMF peaches, the SSC, TS, and pH did not change significantly in S1 or S2.  TA decreased with advancing harvest maturity and decreased slightly in S1 and S2. The FC a-value increased with maturity and was higher in S2 than S1. In Season 2, the results indicated that both MF and NMF peach fruit could be harvested at more advanced maturity stages for S1 than for S2 in order to attain minimum acceptable eating quality. Furthermore, NMF cultivars could be harvested at even more advanced maturity stages than MF cultivars for both storage experiments. This study indicates that NMF cultivars may have the potential to increase peach consumption since they can be harvested at a ‘tree-ripe’ stage and still maintain desirable postharvest qualities during marketing.