Soybean quality loss during constant storage conditions
A modified method for determining free fatty acid (FFA) in crude and refined soybean oils from 0.3 to 6.0 g oil sample size was developed. Good correlation between the modified and official methods was established for crude and refined soybean oils with R2 of 0.9995 and 0.997, respectively. The slopes were 1.01 and 0.99 for the crude and refined oil, respectively.;The number of days soybean lost 0.5 and 1.0% dry matter, for low and high harvest moisture content (MC) soybeans both mechanically and manually harvested, were determined. Soybeans manually harvested at 20% MC deteriorated the (26.2 days) while machine harvested at the same MC were more than 50% faster. At optimum harvest MC (13-14%), 0.5% dry matter was lost in 22.5 days.;Preserved soybeans generally have a higher rate of deterioration during storage than fresh one. The rate declined linearly at 0.21 day/week of preservation during storage for the 9% MC soybeans. There was no change in the 22% MC sample.;The effects of preservation on %FFA and damaged kernels total (DKT) during storage was also evaluated. Soybeans preserved at 22% MC at -18°C temperature exhibited a linear increase in the rate of %FFA content during storage with a slope of 0.2. No significant increase in the 9% preserved sample was observed. %DKT during the storage of 22 and 9% preserved samples were not influenced by preservation.;A relationship between %FFA content and DKT with dry matter loss (DML) during storage were also established. FFA and DKT increased at 0.72 and 3.53% per unit DML, respectively. The combination of the DKT and FFA models as a function of DML characterized grades 1 and 2 soybeans to have less than 0.8% FFA and between 1 and 2% for grades 3 and 4.