Amino acid digestibility studies of autoclaved rapeseed meals using an in vitro enzymatic procedure

Abstract

An investigation of in vitro enzymatic amino acid digestibility of autoclaved rapeseed meals using the enzyme pronase is presented. A correlation coefficient of 0.991 was obtained when comparing in vitro "available" lysine with "Silcock available" lysine. Autoclaving of rapeseed meal for periods of 15, 30, 60, 120 and 180 min at 103 kPa and 120°C caused the following chemical changes. Lysine, methionine and cysteine in vitro digestibilities were markedly decreased as to a lesser extent were the other amino acids. Conversion of methionine to methionine sulphoxide occurred. Deactivation of trypsin inhibitor from 3.8 units of trypsin inhibitor/mg rapeseed for the non-autoclaved meal to zero for the 15 min autoclaved meal was observed. The in vitro enzymatic method described shows considerable promise as a technique to measure amino acid availability.

Effect of the thermal processing on the protein value of double-low rapeseed products. 1. Effect of toasting temperature on protein value of rapeseed oil meal for pigs

“…Thus, increasing toasting temperature from 90 to 100°C, after high moisture conditioning of the seeds, induced much more damage to total and available lysine than toasting at 120°C with lower moisture of seeds. This is in agreement with the earlier observations in which the moisture and height of temperature were found to play essential role in decreasing lysine concentration and availability in RSM (Josefsson, 1975;Rayner and Fox, 1976;Craig and Broderick, 1981;Pickard et al, 1986;Katzer and Minkowski, 1989). \ Laboratory studies (Raczyhski and Buraczewski, 1973;Hurrell and Carpenter, 1977) also clearly showed that decrease of lysine availability in heated protein is associated with an increase of moisture, in particular in the presence of reducing sugars.…”

Availability to pigs of amino acids in cereal grains

“…As in the present experiment, they found that in vitro digestibility values of protein were closely related to in vivo values. Rayner & Fox (1976 found that pronase was also effective in releasing amino acids from rapeseed meal and beef muscle, and that the amount of lysine released was related to the amount of chemically reactive lysine. In the present study, grains of known true ileal digestibility of N and availability of amino acids were used as reference standards.…”

“…Consequently, the in vitro values were of little meaning by themselves as relative indices of digestibility and rely on calibration using standard relationships with values that are biologically meaningful. For example, there would be little value in using chemically reactive lysine values to calibrate in vitro digestibility values for grains, as Rayner & Fox (1976 have done for rapeseed meal and meat, since reactive-lysine content is not necessarily related to available lysine content of cereals . Saunders &Kohler (1972) related in vitro N digestibility andfaecal N digestibility.…”

Impact of technologically processed rapeseeds on the content of glucosinolates

“…Технічним способом теж вдається значно покращити якість ріпакового шроту (тостурування, екструзія, мікронізація і ін.). Однак недоліком останнього є необхідність дії високих температур, які призводять до зниження розчинності протеїну та доступності амінокислот [9].…”