The composition of kibbled and spent carob was determined by a gravimetric analysis and confirmed by an alternative colourimetric method. Kibbled carob comprised: 62% ethanol soluble material, 14% water soluble material, 14% lignin, 5.5% cellulose and 6.6% hemicellulose. The composition of spent carob was 11.3% ethanol soluble material, 28% water soluble material, 35% lignin, 14% cellulose and 11% hemicellulose. The suitability of using spent carob in slurry fermentations with Aspergillus niger M1 was examined. A number of nitrogen sources were tested in 2% spent carob slurries. Ammonium sulphate was chosen for further studies and the optimum concentration of this nitrogen source was sought. Evidence is presented for carbohydrate starvation in 2% spent carob slurries when the nitrogen source was not limiting. Protein production was low, with a maximum yield of 10g protein/100g spent carob, the residue containing 15% protein. Attempts to render the spent carob more assimilable to the fungus by ball milling and alkali-swelling were unsuccessful. Trichoderma koningii M223 was used in a solid substrate fermentation of spent carob producing a residue containing only 8% protein. Trichoderma koningii was shown to produce a cellulase. When Aspergillus niger M1 was used to ferment slurry fermentations of kibbled carob, very high yields were obtained. Eleven grams protein/100g substrate were produced, and the residue contained 27% protein. Combinations of carob concentrations from 2 to 18% and ammonium sulphate concentrations of 0.35% - 2% were examined for their effect on the yield of protein. The tannic content of spent and kibbled carob was found to be 2.2% and 1.3% respectively. Autoclaving the carob was shown to increase the apparent tannin content. The future of the project is discussed.
|Date of Award||1974|