Solid-state fermentation and formulation of non-sterile palm oil processing waste using Rhizopus azygosporus UICC 539

Abstract

This study reported the ability of Rhizopus azygosporus UICC 539 to utilize non-sterile slurry and palm kernel cake (PKC) through solid-state fermentation, preparation of the fungus and non-sterile waste mixture as a formula for animal feed, and analysis of nutrient content of the formula. Fungal culture in PSB at 30 and 40 °C for 5 days was prepared and wet weight biomass was used as inoculum for animal feed formula. Solid-state fermentation (SSF) was carried out on the mixtures of non-sterile slurry and PKC (3:1) at 30 and 40 °C for 5 days and the fermented waste mixtures were dried at 60°C for 5 days. The results showed that during SSF there were presence of colonies of other fungi and bacteria from the waste mixture besides R. azygosporus. The total cell number of R. azygosporus and other fungi were decreased after SSF. Changes in nutrient content in the formula were observed by comparing the treatment and control. Formula prepared at 40 °C showed an increase of carbohydrate content and total calorie, while formula prepared at 30 °C showed an increase only at carbohydrate content. A decrease of protein, water content, ash content, total fat, and energy from fat, was observed in formulas prepared at both temperatures.