THE APPLICATION OF THE DYE-BINDING METHOD FOR MEASURING PROTEIN DENATURATION OF RAPESEED MEALS CAUSED BY AUTOCLAVE OR OVEN HEAT TREATMENTS FOR VARYING PERIODS OF TIME

Publisher Website
Google Scholar
Abstract
Laboratory-prepared rapeseed meals (RSMs) with moisture contents ranging from 2 to 40% of the meal were heated in an autoclave or an oven at 121 °C from 15 min to 4 h. The degree of protein denaturation of the RSMs was estimated by nitrogen solubility (NS) in water and by dye-binding capacity of the protein (DBCP) with Acid Orange 12. The NS study indicated that heating RSM for 15 min to 1 h in an autoclave produced more severe denaturation than heating RSM at a similar temperature for the same periods of time in an oven. When heating in the autoclave was prolonged, the nitrogen solubility increased. The ability of the RSM protein to bind Acid Orange 12 was more severely affected by the autoclave treatment than by oven heating. In this regard, the DBCP of the RSMs was at the lowest after 2 h of heating in the autoclave and after 4 h of heating in the oven. Since the NS values for the RSMs include both protein and non-protein nitrogen while DBCP values measure mainly basic amino acids, the latter values are likely to be more valid for estimating the nutritive value of RSM. The higher correlation coefficient between DBCP and available lysine than between NS and available lysine (0.90 vs. 0.63) would seem to support this conclusion.