Green extractions of bioactive compounds from citrus peels and their applications in the food industry

Citrus peel is the largest waste by mass of citrus fruit mass in the food industry, and it is specifically composed of valuable bioactive components such as phenolic compounds (naringin and hesperidin, predominantly), dietary fibers, essential oils like limonene and carotenoids. Green extraction methods, which refer to environmentally friendly techniques that minimize solvent use and energy consumption, are beneficial for achieving high efficiency in extracting these bioactive compounds. Therefore, it is critical to extract the bioactive components using ultrasound-assisted, microwave-assisted, enzyme-assisted, CO₂ assisted, high intensity pulsed electric field, and so on. Moreover, not only the health benefits of the bioactive components such as anti-inflammatory, anti-cancer, anti-aging, cholesterol reduction effects, but also their potential to be used in functional foods thanks to the functional properties such as gelling agent, emulsifier, pigment and flavor enhancer, antioxidant agent are currently being investigated in the literature. In this review, the extraction of citrus fruits such as lemon, grapefruit, mandarin, orange and pomelo by various green extraction methods and food application studies with their functional properties in recent years have been discussed.