Thiamin content of chicken muscle and effect of purification variables on determined values

Experiments were conducted to investigate 1) effects of selected purification variables [flow rate, temperature, and volume of eluent using two resins, Decalso and Bio-Rex 70 (Bio-Rad Laboratories, Richmond, CA)] on the determined thiamin values of fried chicken and 2) effects of cooking methods on thiamin content of fast food-fried chicken breast muscle using a modified Association of Official Analytical Chemists method. With Decalso, a flow rate of less than 1 mL/min produced satisfactory recovery of thiamin in a standard solution of more than 94%; the use of a faster flow rate of more than 1.5 mL/min resulted in a low recovery value (around 82%). Hot eluent temperature significantly increased thiamin recovery from 90.1 to 99.4%. Thiamin recovery from the Bio-Rex 70 was affected minimally by eluent flow rate, eluent temperature, and eluent volume. A recovery value of about 97% was obtained from the Bio-Rex 70 at all flow rates, with the highest value at 1.5 mL/min. Generally, the use of Bio-Rex 70 resulted in slightly lower determined thiamin values for fried chicken meat but higher and more consistent recovery of a standard thiamin solution than the use of Decalso. The thiamin contents of chicken breast muscles cooked by the two methods were not significantly different (pressure-fried chicken, .207; open vat-fried chicken, .239 mg/100 g on a moisture and fat-free basis).