Comparison of different methods of tannin extraction from the leaves of Iranian walnut (Juglans regia L.) and their effects on chemical composition and fermentative parameters in vitro

The aim of this study was to determine the chemical composition and evaluation of extraction methods of tannin from leaves of Iranian walnut (Juglans regia L.) and estimation of fermentative parameters by gas production technique. Mentioned methods include maceration method, boiling method, percolation method, and Soxhlet method. The results showed that the number of tannins in all the processing methods was reduced significantly compared to the control treatment (p<0.05). Crude protein, crude energy, natural detergent fiber and acid detergent fiber were also increased to compare to other treatments, significantly (p<0.05). Soaking Process compared to other treatments increased significantly cumulative gas production, the fermentable fraction (b) of gas production and also increased insignificantly the parameters of rate (c) of gas production, metabolizable energy, and digestibility of organic matter. Therefore, by comparing the chemical composition and fermentative characteristics of the processed products, it can be concluded maceration method and use distilled water compared to ethanol, is a suitable method for the extraction of tannin and its use in ruminants' feedstuff.