Graduation date: 2006
The objectives of this project were to determine the effects of harvest maturity, packaging, and storage conditions on subsequent fruit quality of Actinidia arguta ‘Ananasnaya’ and to investigate the use of edible coatings to improve fruit quality and storage life. The influences of harvest maturity (6.0, 8.7, 9.1, and 15.1% average soluble solids content (SSC)) and storage conditions (22±1 ºC and 45% RH, or 2 °C and 88% RH for three weeks followed by a ripening period at 22±1 ºC and 45% RH) on the physicochemical, sensory, and nutritive qualities of ‘Ananasnaya’ hardy kiwifruit were investigated. The effects of refrigeration depended largely on maturity of the fruit at harvest. Chroma values of refrigerated fruit ranged from 16.4-19.1 and were similar to vine-ripened fruit (15.1% SSC). Hue angles ranged from 75.4-97.5; the only significant (p<0.05) difference found was for refrigerated fruit harvested at 9.1% SSC, which had lower hue angles than all other treatments. Refrigeration significantly reduced titratable acidity and increased SSC of ripened fruit, regardless
of harvest maturity, and reduced firmness of fruit harvested at 6.0 and 8.7% SSC. However, storage conditions had no effect on firmness of fruit harvested at 9.1% SSC. Free-choice profiling revealed that panelists perceived significant differences between refrigerated and room-stored samples in aroma and flavor descriptors as well as differences between harvest maturity treatments. Refrigerated fruit harvested at 6.0 and 8.7% SSC measured highest in total phenolics with over 2 mg gallic acid equivalents/g fresh weight. Antioxidant activity ranged from 1.6-2.3 ascorbic acid equivalents/g fresh weight with no significant effect of treatment. The postharvest physiology of fruit was monitored for three consecutive seasons, from 2003 to 2005. Fruit were packaged in low- or high-vent plastic containers and stored under room or refrigerated conditions. Calcium caseinate, chitosan, PrimaFresh™, and Semperfresh™ edible coatings were investigated for their potential to enhance the quality and extend the storage life of the fruit. Packaged fruit were exposed to an ethylene-rich environment in the third season to determine the effect of the coatings on ethylene-induced ripening. Semperfresh™-coated and uncoated fruit were evaluated by a sensory consumer panel using a hedonic scale in the third season. Low-vent packaging significantly (p<0.05) reduced weight loss. Refrigerated storage delayed ripening and extended storage life by four weeks. Coatings provided an attractive sheen to the fruit surface and did not impair ethylene-induced ripening. The consumer test indicated that both coated and uncoated fruit were well liked by consumers. These results demonstrated that quality of ripened hardy kiwifruit can be optimized through identification of ideal harvest date for this Actinidia species and by controlling storage
conditions. The results also provide important information regarding the ripening physiology of hardy kiwifruit and indicate that edible coatings may be an alternative to costly low-vent packaging for reducing moisture loss and extending storage life of fresh fruit.