No abstract

A rapid distillation procedure for the estimation of fat oxidation in food using the 2-thiobarbituric acid test has been developed. The apparatus generates steam rapidly and allows high sample throughput while minimizing cleaning of glassware. Using the standard compound, tetramethoxypropane (TMP), and a number of food samples spiked with standard, the recovery of malondialdehyde was determined and suitable operating conditions selected. Levels of TMP equivalent to TBA numbers between 1 and 10 were used. Recovery of standard increased from 25.3% at 20 ml to 81.6% at 120 ml, and recoveries at different TBA numbers were similar. After consideration of various factors, 50 ml was chosen as the distillate volume and was collected in about 4 min. With food samples, the recovery varied depending on the composition of the food and, in order to determine TBA number, it was necessary to calculate recoveries from each type of sample. In the reaction of distillate with thiobarbituric acid, colour development was found to be extremely temperature sensitive, and careful temperature control of the heating bath was required.