Effects of pressing technology of oil separation and heat treatment on the protein value of low-glucosinolate rapeseed cake for non-ruminants
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Mildola Oy, Fin-02401 Kirkonummi, Finland
The Kielanowski Institute of Animal Physiology and Nutrition, Polish Academy of Sciences, 05-110 Jabłonna near Warsaw, Poland
Publication date: 1996-07-09
J. Anim. Feed Sci. 1996;5(3):235-248
The effects of two pressing methods vs solvent extraction, and of different heat treatment of the press cake on the nutritional value of rapeseed protein were studied. Rapeseed cake contained more fat (9-12 vs 4-5% DM) and less protein (31-33 vs 36% DM) than solvent extracted meal while digestibility and biological value of cake and meal protein for rats did not differ significantly (80.9 vs 79.2 and 86.1 vs 83.5, respectively). The incubation of seeds prior to pressing aiming at activation of endogenous enzymes had variable effects. The first batch of the pre-incubated cake had lower lysine content (4.91 vs 5.76g /16g N), ileal digestibility of lysine in pigs (57.8 vs 72.3%) and biological value of protein for rats (78.8 vs 86.8) as compared with solvent meal. The second batch evaluated in rats had lower biological value of protein (81.9 vs 86.1) only as compared with cake from nonincubated seeds. Heat treatment of the cake on pilot scale (autoclaving or toasting and heat - moisture treatment at 120 and 140°C) reduced glucosinolate content from 22.9 to 9.1 µm/g fat-free DM and tended to decrease protein digestibility (from 80.4 to 76.6) but not its biological value. Each step of the industrial technology of pressing (pre-pressing, full pressing, toasting, heating) resulted in lower glucosinolate content (decrease from 13.7 to 5.8 µm/g fat-free DM) and thyroid weight of rats (from 20 to 11 mg/100 g BW) while growth performance of animals and nutritional value of the cake protein were not affected. It was concluded that properly heated rapeseed press cake may have similar protein value for non-ruminants as solvent extracted meal.
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