Circular economy of Castanea henryi: high-value utilization and processing technologies advances

Castanea henryi (Ch) is an underexploited chestnut, has a higher starch content (47.58-56.94%) than other nuts (including C. mollissima, pine nuts, etc.) and is abundant in bioactive substances. Thus, Ch is expected to safeguard human health while relieving arable land pressure. However, there is a lack of a consolidated overview of health benefits and potential applications of Ch and its by-products. The Ch kernel is abundant in resistant starch (65.4% of starch) and polyphenols (1.03-1.07 mg/g), and has lipid-lowering, anti-diabetes, anti-inflammatory, and anti-cancer benefits, enabling it to develop functional products. Notably, severe kernel damage and browning deteriorate its quality during processing. In addition, numerous Ch by-products (such as shells, leaves, flowers, and wood) are often regarded as waste. However, Ch shells and leaves contain rich nutrients, such as polyphenols, flavonoids, proteins, and carbohydrates, which can directly produce functional products, plant substrates, and feedstuff. Meanwhile, the wasted Ch by-products can also indirectly produce some mushrooms, herbs, or animal products. This review integrates advanced knowledge on product development and processing of fleshy fruits, proposing innovative and practical strategies to achieve high-value utilization of Ch kernels and providing insights for the waste utilization of by-products, thereby unlocking their full industrial and health potential.