Fresh-cut melons in many consumer-ready packages are notorious for “wetting” and accumulation of standing juices. These conditions likely create undesirable flavor and aroma changes. We initiated a study to investigate flavor changes in stored fresh-cut cantaloupe. One objective was to optimize solid phase microextraction (SPME) to evaluate organoleptic compounds. Static head-space SPME analyses were performed on fresh-cut cantaloupe cubes (≈2.5 mm, 5 mm, or 2.5 cm), expressed juice, and homogenized slurries. SPME fiber (100 μm PDMS vs. 75 μm Carboxen/PDMS) exposure time (5, 7.5, 10, 12.5, 15, 17.5, 20 min) was evaluated at 40 °C with various head-space: product ratios, plus or minus NaCl to produce typical chromatograms. Fibers were desorbed in an HP5890 GC with a DB-624 or DB-5 column for 45-min runs and an HP6890 GC (DB-5) equipped with a 5973 MS detector for 35-min runs. Albeit qualitative, the best chromatograms were obtained with 7-ml slurries, stirred with NaCl, exposed to a 10 0μm PDMS SPME fiber for 12.5 min. The 100 μm PDMS fiber produced better chromatograms considering the fact that many important flavor volatiles are low-molecular-weight polar esters and alcohols. These conditions were subsequently used to analyze numerous fresh-cut cantaloupe samples stored various times (0 to 9 days). Over 100 peaks were identified, many of which changed through storage and some are suspected as probable agents responsible for undesirable flavor changes. Our analyses are progressing in an attempt to authenticate compounds associated with flavor-related changes in numerous fresh-cut cantaloupe varieties from various growing regions.
John C. Beaulieu, Allison K. Rausch, and Elaine T. Champagne
John C. Beaulieu, Karen L. Bett, Elaine T. Champagne, Daphne A. Ingram, James A. Miller, and Ralph Scorza
Many consumers do not buy peaches due to the fuzzy skin and seed stone and because out-of-season peaches do not possess optimum tree-ripe flavor. The feasibility of using a non-browning freestone peach to deliver high-quality fresh-cut products was investigated. Changes in fresh-cut flavor, texture, and postharvest attributes of commercial-ripe (CR) vs. tree-ripe (TR) harvested and shipped `Bounty' peach was assessed. Fresh-cut CR wedges had an initial firmness of 20.9 N, whereas TR wedges had 11.2 N. On day 2, firmness decreased roughly 3% to 12% and 35% to 45% for CR and TR wedges held at 1 °C, respectively. By day 5, CR wedges hardened (24.5 N) whereas TR did not return to their initial firmness; increasing marginally through day 7. Sensory panel hardness for CR did not change through storage, but with TR wedges, hardness decreased through day 2 then increased until day 7. Little variation was noted in the initial soluble solids for CR vs. TR wedges (11.7, vs. 11.4 °Brix, respectively). After 7 days storage, °Brix decreased 7.5% to 12% in CR and 4.5% to 12% in TR wedges. Yellow flesh color (b*) decreased in all CR and TR treatments through storage. Flavor compounds in expressed juice were analyzed by solid phase microextraction with GC-MS. Several peaks were identified that may be associated with flavor-related changes that occurred during storage. For example, low molecular weight acetates and 6C compounds almost disappeared during storage, whereas short chain fatty acids, lactones, and palmitic acid increased markedly through storage. In TR, the “fruity” descriptor decreased throughout storage and “sweet aromatic” increased slightly (day 2) then decreased through day 7.