Flavonoids in fruits and vegetables after thermal and nonthermal processing: A review

Consumers currently demand more nutritious food, which is minimally processed and naturally produced. Flavonoids are one of the major plant metabolites found throughout the plant kingdom, especially in fruits and vegetables. Flavonoids exert tremendous positive effects on health and protect against various diseases. Fruits and vegetables are difficult to store for a long period, owing to their perishable nature even at low temperatures. Therefore, processing is necessary to prolong their shelf lives and increase nutritional values. Thermal processing has been used in the food sector since ancient times. However, nonthermal processing has become more attractive to consumers and product developers recently, owing to the retention of beneficial health properties after nonthermal processing. The present review will address the effects of thermal and nonthermal processing methods such as blanching, drying, high-pressure processing, ultrasound, pulsed electric field, and ultraviolet irradiation on total and individual flavonoid content in fruits and vegetables. In addition, this text will elucidate the stability characteristics as well as bioavailability, cytotoxicity, and transformations of flavonoids during thermal and nonthermal treatments.