Effect of heating time on yield and quality of soybean meal and oil

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The effect of pre-heating time and number of presses of soybean on the percentage yield and quality of soybean oil and cake were investigated in this study. Pre -heat treatment does not only reduce or denature some anti nutritional factors but it also helps in the process of oil extraction. Pre-heat treatment increased the levels of protein and minerals which can be used in diets to prevent some mineral deficiencies. Ro asting is one of the common ways used to pre-heat soybeans before extraction. The soybean oil extraction parameters examined were percentage yield, free fatty acid (FFA), acid value, peroxide, saponification and ester value. Proximate analysis and percent age cake yield of soybean cake were also studied. The cold pressed (control) single pressed soybean cake (SPSC) had the highest cake yield of 87.17% followed by 86.25%, 85.85%, 84.52% and 82.50% which were pre-heated for 20, 35, 45 and 55 minutes respectively. The corresponding double pressed soybean cakes (DPSCs) had lower yields than their single pressed soybean cakes (SPSCs). Single pressed soybean oil obtained after pre-heating for 35 minutes had an oil yield of 11.35%. Acid value, FFA, ester value, peroxide value and saponification values increased as heating time increased. Double pressed soybean oils (DPSOs) had higher parameters than single pressed soybean oils (SPSOs) of the same pre-heated soybean sample.
A thesis submitted to the Department of Agricultural Engineering in partial fulfilment of the requirements for the degree of Master of Science in Food and Post Harvest Engineering