30B-20 |
Effect of chilling temperature on the polyphenol oxidase activity, color and phenolics in banana skin |
E. CÓRDOVA-DELGADO and E. Mercado-Silva. Departamento de Investigación y Posgrado en Alimentos, Universidad Autónoma de Querétaro, Centro Universitario, Cerro de las Campanas s/n, Querétaro, Qro., 76010, Mexico Banana fruit is an important product in the world, but their conservation is limited due to chilling injury symptoms when is stored under 12°C. The skin browning is the principal symptom and it is attributed to the PPO acting on the phenolics compounds. However, there are few correlation studies about the PPO activity, color development and phenolics content. The objective was to find correlations between de PPO activity and phenolics content with the development of browning in the banana skin. Banana fruit were stored five days at 5, 10 and 20°C, daily samples were taken and analyzed immediately and others were transferred at 20°C for additional three days. Hue and chroma values were measured with a spectrophotometer Minolta C2002, peeling, the skin was freeze drying and used to analyze PPO activity measuring the absorbance changes, using cathecol as substrate, total phenolics content by Folin-phenol reagent, and the leakage ions by a conductivity meter and expressed as percent. On day three the PPO activity was 12271 UA/g FW at 10°C and 13571 UA/g FW when the samples were transferred at 20°C. At 15°C it was 11616 and 14 271 UA/g FW in the samples transferred. The leakage ions was higher in the samples stored at chilling temperatures and transferred at 20°C (55% y 62%) than the samples stored at 20°C (33.1%). The phenolics content increased from 3.5 mg at 20°C to 5.3 mg cumaric acid/ g FW in the samples at 10°C indicating a synthesis process. The PPO activity and phenolics behavior were correlated inversely with Hue value and directly with chroma. The browning process was correlated with the PPO activity but also during the process there are synthesis of phenolics and lost membrane permeability that contribute at development of the changes in color.
Session 30B, Fruit & Vegetable Products: Sensory, Product Development, Fresh-Cut, and Storage
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