Protein enrichment of orange wastes by filamentous fungi.
2007
Biniyam Yalemtesfa(Researcher)
Orange peel and pulp are rich in carbohydrates but poor in protein and account for approximately 55 to 60% of the weight of the raw/whole fruit. Their high cellulose and low protein content prevents them from being used as non-ruminant feedstuff while their high moisture content leads to difficulty in storage. However, the orange waste is highly susceptible to hydrolysis by mixtures of cellulytic and pectinolytic enzymes which makes it attractive potential feedstock for biological conversion to value added products. To this effect, two fungal species namely, Aspergillus niger (KA-06) and Chaetomium spp (KC-06) were used to enrich the orange wastes with protein in solid state fermentation. The mycelial biomass of KC-06 was found to have 37.64% protein and KA-06 had 34.2% protein when grown in malt extract broth. The effect of various process parameters were studied in solid media of orange pulp. The optimum duration of fermentation was found to be 5 days and 4 days for KC-06 and KA-06 respectively. The optimum conditions for the enrichment process were found to be moisture content 40%; temperature 25% and substrate load 10 g for both KC-06 and KA-06. pH 7 gave highest protein yield by KA-06 whereas pH 5.5 was optimum for KC-06. Inoculum concentration 108 spores/ml was the best dose for KC-06 as 106 spores /ml was for KA-06. Among the nitrogen supplements studied, (NH4)2SO4 gave the highest protein yield by both fungal species. The growth of KC-06 on orange waste has improved the protein content up to 39.64% and KA-06 was able to enrich the feed with 34% protein.
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