Quality characteristics of fresh-cut watermelon slices from non-treated and 1-methylcyclopropene- and/or ethylene-treated whole fruit
Maintaining the postharvest quality of fresh-cut fruit after processing and throughout distribution and marketing is a major challenge facing the fresh-cut fruit industry. Analytical quality characteristics of packaged fresh-cut watermelon slices from non-treated and 1- methylcyclopropene (1-MCP)- and/or ethylene-treated whole fruit were investigated. Freshly harvested seedless watermelon (‘Sugar Heart’) were stored 7–14 days in air before exposure to 0, 0.5 or 1.0 µLL−1 1-MCP for 18 h followed by 5 days exposure to 0 or 10 µLL−1 ethylene, all at 20 °C. Following treatment, fruit were processed into wedge-shaped slices, packaged into rigid trays sealed with a high oxygen transmission rate film overlap and stored 1, 6 or 12 days at 5 °C. During storage, fresh-cut watermelon slices from non-treated and 1-MCP- and 1-MCP + ethylene-treated whole fruit maintained similar respiration rates and internal atmospheres of CO2 and O2 and were of similar quality with total aromatic volatile concentrations decreasing and puncture firmness, soluble solids content (SSC), cut surface pH and color remaining relatively stable. In contrast, fresh-cut slices from fruit treated with ethylene alone had higher respiration rates and modified package atmospheres containing more CO2 and O2; lower firmness, SSC and chromaticity values; higher pH and an altered volatile profile compared to those of slices from non-treated and 1-MCP- and 1-MCP + ethylene-treated fruit. The 22 most abundant volatiles were various aldehydes, alcohols and ketones. During storage, many individual volatiles decreased in concentration but some increased including (Z)-6-nonen-1-ol, a volatile having a pumpkin-like aroma. The results indicated that low dosage 1-MCP treatments prior to ethylene exposure of whole watermelons prevented ethylene-mediated quality deterioration in fresh-cut slices stored under modified atmosphere conditions at 5 °C.