Postharvest quality of cashew apple after hydrocooling and coold room

Abstract

Cashew (Anacardium occidentale L.) is composed of two distinct parts: the nut (fruit), which represents only 10% of the total weight of the harvested product, and the cashew apple (pseudo-fruit), usually known as cashew. This study aimed to determine the hydrocooling temperature of cashew apples and its effects on quality maintenance. Cashews were hydrocooled (HC) by immersion in chlorinated water at 1, 3, 5 and 7 °C. Fruit were cooled in a refrigerator at 5 °C as controls. After treatments, all the fruit were stored at 5 °C for 15 d, and cooling rate, color, freshness, visual assessment, weight loss, and thermal properties were evaluated. Fruit hydrocooled at 1 and 7 °C had lower visual quality and wilting, and greater weight loss, 3 °C was discarded by did not show evident results. A temperature of 5 °C was selected for further studies. Cashew apples were HC at 5 °C, and control treatment cooled in display cold room (CR) at 5 °C, and then fruit from both treatments were stored for 25 days. Samples were taken for physical, physico-chemical and enzymatic analyses at 5 days intervals. HC fruit showed greater freshness, higher firmness and acidity, and slower losses of fresh weight loss and vitamin C when compared with CR. Total phenolic contents decreased during storage, but little effect of treatment on the rate of decline was detected. However, activities of polyphenol oxidase and peroxidase were generally higher in cashew apples with CR than after HC. Red color loss of the cashew apples was constant during storage, regardless of the cooling method. Our study shows that 5 °C is the minimal temperature for hydrocooling of cashew apples, to decrease the risk of damage by cooling, and that this temperature is the optimal temperature for storage of cashew apples