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

Abstract

The effect of toasting process in the industrial conditions at 90,95, 100 (Plant 1) and 120°C (Plant 2) on protein value of a double-low rapeseed meal (RSM) for pigs was studied in two experiments. In Experiment 1, the ileal digestibility of RSM was evaluated, and in Experiment 2, the N balance and growth performance trial was carried out.It was found that raising of toasting temperature from 90 to 95 and 100°C in Plant 1 decreased the total and available lysine contents (5.20, 4.85, 4.33 and 4.28, 3.84, 3.00 g/16 g N, respectively). The apparent ileal digestibility of protein and, in particular, lysine was also reduced (63.7, 65.5, 57.6 and 66.6, 66.8,49.6, respectively). Feed intake, body gain, feed utilization and N utilization by pigs were decreased (P^O.01) as toasting temperature increased from 90 to 100°C. The nutritional value of RSM was not reduced when it was toasted at 120°C in Plant 2 and was comparable to the nutritional value of RSM toasted at 90°C in Plant 1.It was concluded that protein value of RSM for pigs obtained from Polish oil factories using solvent extraction, is highly dependent on the toasting temperature. But other parameters of rape seed processing such as moisture and duration of heating may also affect the nutritional value of RSM for pigs.

Effect of thermal processing on the protein value of double-low rapeseed products. 2. Effect of processing stages in the oil plant and of toasting in laboratory conditions

“…These results confirmed findings obtained in the study by Grala et al (1994) who showed that increasing toasting temperature from 90 to 100°C markedly decreased protein value of RSM, especially the content of total and available lysine as well as the apparent ileal digestibility of protein and amino acids, N utilization and pig performance. In the present study the protein quality (TD, BV, NPU) and growth performance of rats (FC, BWG) decreased as lysine and available lysine contents in protein was reduced.…”

“…The protein value of seeds and cake was not directly dependent on total or available lysine concentrations in protein, in contrast to those samples which were heated (autoclaved) in the laboratory (Expt. 3) or to RSM toasted in the oil plant (Grala et al, 1994). Similarly to our study, other authors also showed that mild hydro-thermal treatment of double-low rape seeds increased their biological value (Slomiriski et al, 1985;Rakowska et al, 1987;Rotkiewicz, 1991).…”

“…Jantar) and their processed products were obtained from the same oil factory where the samples of rapeseed meal were taken for previous study by Grala et al (1994).…”

“…The autoclaved defatted cake was named as "heated cake". Temperature of 100 and 120°C was chosen, since such toasting temperatures were applied in the oil plant (Grala et al, 1994).…”

“…Previous studies by Grala et al (1994) showed that the toasting temperature was not the only technological parameter which should be modified to improve the protein value of double-low rapeseed meal produced by Polish oil industry. It was found that protein value of rapeseed meal was negatively influenced by the increase of temperature in one plant, while toasting at even higher temperature in another one did not decrease protein value or pig performance.…”