A Review of the Bioactive Compounds of Kiwifruit: Bioactivity, Extraction, Processing and Challenges

Kiwifruit is widely consumed in many parts of the world. They contain a variety of bioactive substances that make them a valuable functional food source. For instance, kiwifruit contains vitamin C, polysaccharides, polyphenols (catechin, anthocyanin, chlorogenic acid, gallic acid), alkaloids (aconitine, safranin, actinidine), and terpenoids (ursolic acid, oleanolic acid), which are claimed to exhibit antioxidant, anti-inflammatory, and anticancer effects, as well as protecting against cardiovascular and cerebrovascular diseases. However, the potentially beneficial effects of most of these bioactive substances have still not been confirmed by clinical trials. This article reviews recent research on the type and physiological functions of the main bioactive components in kiwifruit. The techniques required to extract and characterize these components are discussed, as well as current challenges in kiwifruit processing. Several innovative extraction techniques have been utilized to extract bioactive substances from kiwifruits, including ultrasound- and microwave-assisted methods. Moreover, several non-thermal processing methods (such as sonication, high-pressure, and pulsed electric field processing) are being used to reduce the losses and increase the activity of bioactive substances, preserve the sensory qualities of the fruit, and reduce the allergenicity of kiwifruit.