True ileal amino acid digestibility and digestible amino acid scores (DIAASs) of the cruciferin and napin fractions of rapeseed: Impact of processing.

Processes are being developed to exploit proteins from the residue of rapeseed oil extraction. Two main fractions of proteins can be purified: cruciferin and napin. The present work was carried out to characterize the nutritional quality of these fractions, while exploring the effect of the extraction conditions (neutral or acid), and that of the post extraction process (heating 1 h, 120 °C). The true ileal digestibility (TID) of their amino acids (AA) was measured in minipigs, to calculate the digestible indispensable amino acid score (DIAAS). The TID of cruciferin was high (95 %) compared to that of napin (87 %). The extraction process and the heat treatment had no effect on the TID of napin. The DIAAS for adults was 117 % for cruciferin, and 82-89 % for napin (branched-chain AA being the limiting AA). Improving the TID of napin would enable this interesting source of cysteine and lysine to be better exploited in human nutrition.