Methods for determining thioglucosides in<i>Crambe abyssinica</i>

McGhee, J. E.; Kirk, L. D.; Mustakas, G. C.

doi:10.1007/bf02541187

Cited by 40 publications

(13 citation statements)

References 6 publications

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“…Van Etten et a1. 16 and McGhee et al 30 have devised methods for determination of released sulphate, which will be further discussed below. Bauer & Holle31 determined sulphate in acid hydrolysates of white mustard extracts.…”

Section: Discussionmentioning

confidence: 99%

Method for quantitative determination of isothiocyanates and oxazolidinethiones in digests of seed meals of rape and turnip rape

1967

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A method has been developed for the quantiitative determination of isothiocyanates and oxazolidinethiones in enzymic digests of seed meals of rape (Br,issica napus) and turnip rape (B. campestris). Good precision has been obtained; relative standard deviation was *2% when the method was applied with macro-(1 g) as well as on micro-amounts (10 mg) of seed meal.In order to obtain optimum yields from the same digests, the seed and meal were treated with hot air and hot buffer solution, respectively. The time,'temperature/moisture relationship of seed treatment necessary to inactivate the myrosinase in rape seed is presented.The results obtained with this method demonstrate that the content of progoitrin in rape seed is considerably higher than that obtained by application of an earlier widely used method, e.g. 4.8 % in defatted seed meal of Matador winter rape, compared with an earlier figure of 3 . 1 %.Introduction Defatted meals of rape and similar cruciferous seed crops have a high protein content and a reasonably well balanced amino acid composition? However the large amounts of thioglucosides present, which yield isothiocyanates and oxazolidinethiones upon enzymatic hydrolysis, limit their use as feed. Plant breeding projects to obtain varieties with the lowest possible content of such compounds have been initiated.2 With Wetter's method39 for the assay of these products of hydrolysis, problems in reproducing the results on oxazolidinethione content in a given seed sample on different occalsions were experienced. Several authors have reported a broad pH optimum at 7 for the action of myrosinase on purified thiogluc0sides5.~ whereas Wetter found a pH optimum at 4 for isothiocyanate formation in the presence of rapeseed meals. Preliminary experiments showed a higher rate of isothiocyanate release from a seed meal slurry at pH 4 than at 7 whereas in aqueous solutions of methanol extracts of the same meal the rate was higher at pH 7 than at pH 4. Thus, it was considered essential that studies on the conditions for the release of isothiocyanates and oxazolidinethione from the parent thioglucosides should be undertaken. Furthermore, a less time-consuming method, adaptable to micro-quantities was desired. The results of these studies are presented in the present paper. A preliminary report covering the principles of this new method has been published elsewhere.7Structure of thioglucosides and various split products in rape and turnip rape seeds Through degradation of two natural thioglucosides, sinigrin and sinalbin,8 and total synthesis of another naturally occurring thioglucoside, glucotropaeolin,g Ettlinger & Lundeen provided conclusive evidence for the thioglucoside structure depicted in Fig. 1. The major thioglucosides in rape and turnip rape are gluconapin and p r~g o i t r i n .~ For gluconapin the R in Fig. 1 corresponds to CH2 = CH -CH2 -CHz -; for progoitrin it is CH2 = CH-CH(OH)-CHZ-. FIG. 1. Enzymatic hydrolysis of thioglucosides at pH 7Hydrolysis of pure thioglucosides at neutral pH by an enzyme preparat...

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Section: Discussionmentioning

confidence: 99%

Method for quantitative determination of isothiocyanates and oxazolidinethiones in digests of seed meals of rape and turnip rape

1967

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“…Total glucosinolate, thioglucoside, was determined by the sulfate method of McGhee, et al, (6). Glucosinolate precursors of volatile isothiocyanates were determined by the method of Wetter (18), and epi-progoitrin glucosinolate was determined by enzymatic conversion to goitrin.…”

Section: Methodsmentioning

confidence: 99%

“…The feeding value of the meal is greatly impaired, however, by the presence of undesirable compounds known as glucosinolates. These compounds have been extensively investigated at the Northern Laboratory (5,6).…”

Section: Introductionmentioning

confidence: 99%

Crambe seed processing: Removal of glucosinolates by water extraction

Mustakas

Kirk

Griffin

et al. 1976

J Americ Oil Chem Soc

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A method is reported for removingepi‐progoitrin, the major glucosinolate, from crambe seed meal. Defatted meal was cooked and water extracted or treated with soda ash and then water extracted. Although soda ash aided destruction and removal of glucosinolate factors, there was a 28% reduction in total lysine. In animal feeding tests designed to reflect differences due to toxic factors, soda ash treated and water extracted meals gave the best results. No toxicity was apparent in rats and chicks fed these meals in nutritionally adequate diets. The rat diet included 30% crambe meal for 90 days; the chick diet, 20% crambe meal for 4 weeks. Pathological examinations in both series showed no organ damage.

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“…A developing effort on replacement vegetable oils like Crambe abyssinica (ca. 52-57% erucic acid content) (6,9,10)could materialize in time to afford the U.S. sufficient quantities of erucic acid, or (after hydrogenation) the C-20, 22 (behenic) and 24 saturated fatty acids; but polyunsaturated fish oils can be counted on only for the saturatedC-20, 22 and 24 acids (with hydrogenation).…”

Section: Fatty Acid Composition Changes In Raw Materials Vegetable Oilsmentioning

confidence: 99%