Nutrition, Safety, and Utilization of Tea By-products in Fujian

Objective  Safe utilization of by-products from the tea processing industry in Fujian Province was evaluated.

Method  Forty samples of by-products from the vast varieties of tea products manufactured in the province were collected from different regions to analyze the chemical compositions of nutritional substances, amino acids, functional ingredients, and heavy metals in them. Potential applications of the material for animal feeds were evaluated.

Result Of all specimens, the by-products of green tea had significantly higher contents of polyphenols, catechins, and crude protein (P＜0.05), while those of oolong tea were lower on Pb and more prominent in theanine with a content 4.3 times of green tea. Tea dregs, or residues from processing or brewing tea, contained high levels of neutral detergent fiber and calcium as well as Cr and Pb that exceeded significantly the safety standards on heavy metals. The samples collected from different regions in the province varied significantly in crude fat, gallic acid, epigallocatechin, catechin, epigallocatechin gallate, epicatechin, arsenic, and cadmium contents (P＜0.05).

Conclusion The tea by-products in the province could potentially be utilized to formulate forage for animal husbandry. For instance, green tea by-products could be used as a protein and antioxidant supplement, and oolong tea by-products as a functional additive. On the other hand, the high heavy metal content of tea dregs might present a safety concern in application.