Effect of Moisture Content on some Quality Parameters of Mechanically Expressed Neem Seed Kernel Oil

Abstract

The effect of moisture content on some quality parameters of mechanically expressed neem seed kernel oil was investigated. The quality parameters include saponification value, iodine value, fatty acid, acid value and colour. They were determined according to standard methods and were determined in three replicates. Matured neem seed kernels were obtained and the initial moisture content determined. The neem seed kernels were then preconditioned to the following moisture content values: 6.3, 8.1, 13.2 and 16.6 % (wet basis), based on reported values for oil seeds meant for oil extraction; the seed kernels were then subjected to oil extraction using an oil expeller. The oil obtained at the different moisture contents was then subjected to standard tests to determine the effect of these moisture contents on the quality parameters of the oil. New Duncan’s Multiple Range Test (DMRT) was used to determine the differences in the mean treatment effect of moisture content on the different quality parameters. From the results obtained, highest saponification value of 262.46 was obtained with Moisture content at 8.1%, thereafter the saponification value decreased as the moisture content was increased. Iodine values increased as the moisture content increased from 6.1% to 8.1%, decreased sharply at 13.2% and then increased sharply at 16.6%. Moisture content seems to have increasing, decreasing, and then increasing effect on the values of the free fatty acid. Moisture content has an upward and downward effect on acid value. It was observed that moisture contents at higher levels affected the colour of the oil, which changed from brown to dark brown. From the foregoing, it can therefore be deduced that moisture content has an effect on the quality parameters of neem seed kernel oil.