Effects of processing on the nutritional quality of canola meal

Two 10-day chick bioassays and two amino acid digestibility trials using cecectomized cockerels were conducted to assess the effects of steam heating and commercial processing on in vivo protein quality of canola meal. In vitro protein solubility measurements in 0.2 or 0.5% KOH were evaluated as predictors of in vivo protein quality. Commercial solvent-extracted canola meal autoclaved at 121 C and 105 kPa (international pressure units) for 0, 10, 20, 30, 40, 60, or 90 min, was fed to 8-day-old chicks in corn-canola meal diets containing 20% CP. Growth performance of chicks fed autoclaved canola meal decreased linearly (P 0.001) as autoclaving time increased. The analyzed lysine content in canola meal was reduced markedly by increased autoclaving time, with little or no effects observed for other amino acids. True digestibilities of indispensable amino acids decreased (P 0.05) as autoclaving time increased, with lysine providing the most notable change. The decreased digestibility of lysine was due both to reduced concentration digestibility of the analyzed lysine and to reduced digestibility of the analyzed lysine remaining after autoclaving. Protein solubility in 0.2 and 0.5% KOH decreased as autoclaving time increased. Use of 0.5% KOH provided a larger range in solubility values over autoclaving times. Four samples of canola from different stages of processing (full-fat seeds, flaked or conditioned meal, expeller meal, and solvent-extracted meal) were also evaluated. Protein solubility in 0.2% KOH decreased upon solvent extraction, but there were no significant changes in amino acid digestibility due to stage of processing