Detannying in Cashew Apple Juice (Anacardium occidentale L.) by Chemical Agents

Abstract

Vietnam is the leading exporter of cashew nuts globally; however, the cashew apple, constituting 75% of the total harvest from cashew trees, remains underexploited despite its rich nutrient content. The main reason is that cashew apple contains high amount of tannin which causes astringency. Consequently, this undesired compound poses a significant challenge for food product development. Thus, tannin removal is critical in cashew apple juice processing to improve sensorial characteristic and produce a nutritious beverage from cashew apple. Gelatin, modified cassava starch (MCS), and polyvinyl polypyrolidone (PVPP) are the most recommended agents for tannin reduction. This study evaluated the efficacy of these clarifying agents based on agent concentration, processing time, and juice pH. Results indicated that gelatin at 2 g/L for 30 min at pH 3 reduced tannin by 34.31%; MCS removed 41.34% of tannins at 3 g/L for 30 min at pH 3; and PVPP achieved tannin removal of 32.45% at 4 g/L for 30 min at pH 4. All chemical treatments decreased nutritional values, including vitamin C, sugars, polyphenols, and antioxidant activity. While MCS demonstrated the highest tannin removal efficiency, the sensory quality of the treated juice requires further enhancement due to low pH.