Nutritional Evaluation of Low-Glucosinolate Rapeseed Meals Obtained by Various Processes

Abstract

Defatted meals were prepared from two new varieties of rapeseed, the ‘high-glucosinolate’ variety, Brassica napus, Lesira, and the ‘low-glucosinolate’ variety, Brassica napus, Erglu, by each of the following processes: (1) defatting of the ground seed with hexane; (2) extraction of the myrosinase-deactivated ground seed with 70% aqueous acetone for the removal of glucosinolates followed by defatting with pure acetone, and (3) autolysis of the ground seed for the decomposition of glucosinolates followed by defatting and simultaneous removal of the decomposition products with hexane. The defatted meals obtained after extraction with aqueous acetone or autolysis contain very little glucosinolates and their degradation products as compared to those obtained by defatting with hexane only. The contents of available lysine and of phytates in the meals are, to some extent, affected by the treatment for the removal of glucosinolates. The rapeseed meals were fed at different levels to protein-depleted chicks and weanling rats. The animals fed low-glucosinolate meals prepared both from high-glucosinolate and low-glucosinolate varieties of rapeseed gave superior performance with regard to the feed conversion and protein efficiency ratio as compared to the animals fed the corresponding meals which were obtained simply by defatting the seeds with hexane. The levels of thyroxine (T₄)and triiodothyronine (T₃) in the serum of rats fed low-glucosinolate meals indicated normal function of the thyroid, whereas those in rats fed high-glucosinolate meals revealed hypo-thyroidism of the animals.

Rapeseed: Constituents and protein products. Part 3. Nutritional value of protein‐enriched products

“…Seed meal from a combined extraction of harmful substances and oil after previous autolysis of the seed is likewise improved in nutritional value [127] but does not achieve the quality of acetone-extracted seed meal (PER value 1.76 compared to 2.59).…”

Proteins from double-zero rapeseed

“…Rapeseed and related cruciferous oilseed crops are a rich source of protein (Finlayson, 1976) glucosinolates (Ballester et al, 1970; Bhatty and Sosulski, 1972; Kozlowska et al, 1972;Mukherjee et al, 1979) and preparation of protein concentrates (Eapen et al, 1969;Jones, 1979;Ohlson and Anjou, 1979;Thompson et al, 1976Thompson et al, ,1982 and protein isolates (Owen et al, 1971;Kodagoda et al, 1973; Gillberg and Tornell, 1976a; Aman and Gillberg, 1977; El Nockrashy et al, 1977; Blaicher et al, 1983). Rapeseed meals and protein concentrates as well as isolates prepared therefrom contain unusually high levels of phytic acid (Jones, 1979;Blaicher et al, 1983), which can cause deficiency of certain minerals, especially zinc, that must be compensated by suitable supplementation (Jones, 1979).…”