Nutritional Value and Safety Characteristics of Processing By-Products from Different Tea Types in Guizhou Province

This study systematically evaluated the nutritional composition and safety characteristics of processing by-products from major tea types in Guizhou Province, aiming to explore their potential for feed utilization. A total of 40 samples of processing by-products from different tea types (black tea, white tea, green tea, oolong tea) and tea beverage processing (tea residue) in Guizhou Province were collected and analyzed. The conventional nutritional components, amino acid composition, biochemical components, and heavy metal contents were determined, and the category characteristics were analyzed by ANOVA difference analysis and cluster analysis. The results showed that the green tea processing by-products had significantly higher contents of tea polyphenols, total catechins, and crude protein than those of other tea processing by-products (P<0.05); the oolong tea processing by-products had a prominent theanine content, which was 4.1 times that of green tea processing by-products, and a lower lead (Pb) content; the tea residue had high contents of neutral detergent fiber and calcium, but the contents of heavy metals chromium (Cr) and lead (Pb) posed potential feed safety risks. Green tea processing by-products can be used as high-quality feed protein sources and natural antioxidants, oolong tea processing by-products are suitable for functional feed development, and special attention should be paid to the heavy metal content when utilizing tea residue. This study provides a scientific basis for the classified feed application and safety control of tea by-products.