76C-23 |
Gloss evaluation of coated mandarins cv.‘Fortune’ by sensory and instrumental techniques |
C. Rojas1, M. B. PÉREZ-GAGO1, and M. A. del Río. (1) Postharvest, Instituto Valenciano de Investigaciones Agrarias, Ctra Moncada-Naquera km4.5, 46113 Moncada, Spain Citrus are waxed to replace natural waxes lost during washing, conferring shine and creating a barrier to moisture and gases. Resin-coatings provide high gloss but, due to its high gas barrier, they can induce off-flavors when are applied at high resin levels or total solid content (TSC). Plasticizers can be added to minimize off-flavors by decreasing gas barrier. Instrumental techniques can be used to measure fruit gloss. However, these values may differ from human perception. The objective of this work was to compare sensory and instrumental gloss of mandarins coated in solutions having different plasticizer level or TSC. Edible coating (EC) materials consisted on locust bean gum, beeswax, Tween-80, shellac and glycerol. Three solutions were tested: F4, F4-[50%] and F4-p. Uncoated or dip-coated mandarins were stored at 20ºC for 14 days or at 9ºC for 28 days. F4 and F4-[50%] coatings differed on TSC: 5.2% and 2.6%, respectively. F4 and F4-p coatings had 5.2% TSC and the shellac/glycerol ratio was 6/1 and 3/1, respectively. Gloss was measured with a micro-gloss 60º and by a trained panel who ranked mandarins from highest to lowest gloss. Weight loss and ethanol content were also determined. Gloss of coated mandarins at high TSC (5.2%) was significantly higher than coated mandarins at low TSC or uncoated mandarins. No gloss differences were detected by sensory evaluation when EC differed on shellac/glycerol ratio; however, discrimination was possible instrumentally. Weight loss of coated mandarins was not different when EC had high TSC. The highest ethanol content detected when low plasticizer level was used suggests that this coating is not appropriate for long-term storage. EC solutions with higher plasticizer ratio would be more desirable to minimize off-flavor risk. Controlling plasticizer level and TSC of EC solutions is necessary to optimize coating functional properties, such as gloss and barrier properties.
Session 76C, Fruit & Vegetable Product: Fresh Fruits and Vegetables
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