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

Abstract

The effects of two main processing stages (cooking and toasting) in extraction plant on the nutritional value of double-low rapeseed products were studied. Raw seeds and cooked cake taken from the oil factory were defatted and compared with toasted rapeseed meal in N balance/growth performance experiment with rats and in growth performance experiment with brolier chickens. Moreover, the effect of temperature and time of heating in the laboratory (100 and 120°C for 10,20 or 30 min) on protein value of defatted expeller cake was also studied in N balance/growth perfomance experiment with rats.The toasting process had the most depressing effect on the content of total and available lysine and of glucosinolates as compared to their level in the seeds. The rats and chickens fed with diet containing toasted rapeseed meal performed better than those fed with diets containing non-heated defatted rape seeds or cooked and defatted cake. The toasting process reduced harmful effect of rape seed on (P^O.01) the thyroid and liver weights of rats and thyroid weight of chickens.Increasing temperature and time of laboratory heating resulted in linear decrease (P^ 0.001) in lysine, available lysine and glucosinolate contents as well as protein value of defatted cake for rats (TD, BV and NPU). However, the decrease in lysine content was much more dependent on the increase of temperature than on the prolongation of heating. The performance of rats (body weight gain, feed utilization) was influenced (P^O.01) by both factors. Feed intake and weight gain of rats decreasd as time of heating increased but only at higher temperature (120°C). The thyroid weight linearly deceased (P^O.01) as temperature increased.It seems that toasting of double-low RSM in mild conditions is necessary to eliminate the negative infuence of residual glucosinolates on the animal performance.

Effects of pressing technology of oil separation and heat treatment on the protein value of low-glucosinolate rapeseed cake for non-ruminants

“…The results of balance experiments with rats indicating for similar digestibility and biological value of the cake and meal protein, are consistent with the results of Grala et al (1994) and Rakowska and Ochodzki (1995).…”

“…It may be therefore assumed that similar feed intake and growth rate in animals fed on cake and on meal in our experiment are related to a rather small goitrogenic effect of evaluated cake (thyroid weight 14 vs. 10 mg/100g body weight in rats fed on cake and meal, respectively), smaller than that found by Grala et al (1994) (16.5 vs 7.5 mg/100 g body weight).…”

“…These results are in agreement with those of Jensen et al (1994) who found that prolongation of toasting of rapeseed meal in 100°C from 0 to 15, 30 and 60 min caused a slight decrease of TD without any effect on BV of protein, which was depressed only when the meal was toasted during 120 min. In the study of Grala et al (1994) reduction of BV of defatted cake was observed after 30 min of toasting at 100°C and 10 min at 120°C while TD of protein decreased when time of heating at 120°C was extended.…”

“…Negative effects of glucosinolates on feed intake, growth rate and thyroid functions were observed in many animal species (for review see Mawson et al, 1994 a, b). It is also well known that overheating may decrease total and available lysine content and impair protein utilization (Anderson-Hafermann et al, 1993;Grala et al, 1994;Jensen et al, 1994). Thus heating parameters such as temperature, duration and moisture should be carefully chosen to ensure the high protein value of processed rapeseed feeds.…”

Value of hydroalcoholic treatment of rapeseed for oil extraction and protein enrichment

“…After oil extraction, the rapeseed meal contains around 35-40% proteins, plus carbohydrates (30-35%), crude fiber (10-15%), minerals (5-10%), and up to 10% secondary plant metabolites (von der Haal et al, 2014;Carré et al, 2016). However, the current rapeseed oil production-line configurations limit the production of a digestible protein-rich meal (Grala et al, 1994;Adem et al, 2014;Mosenthin et al, 2016). The presence of anti-nutritional components (fibers, glucosinolates, phytates and phenolics) and the loss of protein solubility during the crushing process hinders further value recovery (Bell, 1993;Quinsac et al, 1994;Adem et al, 2014).…”