Polyphenols in Food Industry: Enhancing Quality and Nutritional Value<i></i>

Polyphenols are known as secondary metabolites, which are crucial bioactive compounds that enhance human health. Chromatographic methods typically identify polyphenols after food extraction. The extraction methods are fundamental; however, they can be used with any differences, including extractant type, according to the food. Polyphenols are mostly found in some foods, including grapes, olives, cherries, and apples. Foods have divergent polyphenols, which differentiate according to the food types. Moreover, they have flavonols, flavanols, flavones, flavanones, isoflavones, and anthocyanins as various subgroups of polyphenols that can change in terms of quantity and quality with several factors, including types, growing region, germination time, and harvest season of food. The consumption of polyphenols is crucial for human health owing to their anti-cancer effect, anti-tumor effect, anti-inflammatory effect, cardiometabolic risk management, antimicrobial effect, immunomodulatory activity, and antioxidant activity. These are given attention by researchers who detect the effects of polyphenols. In the valorization of polyphenols, the consumption dose is also important to effectively benefit from the polyphenols of plant-based foods. Several in vitro and in vivo studies have tested the polyphenols’ digestion ability and preservation ability in gut microbiota and their effect on the microbiota to determine the benefits and effects of polyphenols in several areas. According to these studies, polyphenols can be used to fight against the disease. In addition, divergent applications, including encapsulation and polyphenol coating, are used to stabilize, preserve, and improve the bioaccessibility of the polyphenols. Even though polyphenol-rich foods are consumed for nutrition in daily life, they are also used as nutritional ingredients in the food industry to produce functional foods, and functional foods are enriched with food by-products to enhance their nutritional value, especially in terms of polyphenols. Especially, waste food by-products are used to enrich the functional foods, which are preferred in healthy life diets, especially because of the diversity and amount of bioactive ingredients, including polyphenol types of the waste food by-products. Furthermore, polyphenols also provide the preservation ability of storage and improve the bioaccessibility of bioactive ingredients in the digestion of functional foods.