Bioconversion of rubber seeds to produce protein and oil-rich biomass using black soldier fly larva assisted by microbes

Abstract

A co-conversion process using black soldier fly larvae (Hermetia illucens) and microbes was studied to convert rubber seeds into prepupal biomass from May to November 2016. De-oiled rubber seeds from West Bandung, Indonesia (cake to shell ratio of 2.5 wt%) was mixed with water (water to biomass ratio of 1.5-2.3 wt%) and pre-treated with two types of microbes; a liquid culture of Aspergillus niger (107 spore/ml) and a Biotaff solution containing consortium of microbes (107 cell/ml). Black soldier fly larvae were reared in rearing containers with a feeding rate of 68 mg/larvae/d and subjected with different shade rate (50-100%). The highest prepupal biomass productivity of 124.2 g/m2.d on a dry basis with an assimilation efficiency of 28.7% and efficiency of conversion of digested feed of 25.9% was obtained when the larvae were cultivated using shade rate of 100% and fed with a substrate that had been pre-treated with a Biotaff solution containing 107 cell/ml. At this condition, the prepupal biomass has a protein content of 28.6 wt% and a fat content of 28.3 wt% which mainly consists of lauric acid (24.6%), oleic acid (24.5%), linoleic acid (19.3%) and palmitic acid (18.4%).