Bitterness in brussels sprouts (Brassica oleracea L. var. gemmifera): The role of glucosinolates and their breakdown products

The bitterness associated with certain cultivars of Brussels sprouts has been shown to be linked to the presence of the glucosinolates, sinigrin and progoitrin. Whereas the former compound is bitter per se, the bitterness associated with the latter compound is due to its decomposition product, the goitrogen (-)5-vinyloxazolidine-2-thione. A method is described for the screening of cultivars of this, and other, Brassica vegetables for potential bitterness.     

The chemical composition,the nutritive value and the functional properties of malt sprout and its components (acrospires,rootlets and husks)

The components of malt sprouts were effectively separated by manual winnowing into acrospires (15·3%), rootlets (40·1%) and husks (43·7%). The bitter taste was located in the acrospires. Percent recovery of protein and fibre was, respectively, 95·2 and 87·2 of malt sprouts. The acrospires were rich in protein (30·3%) and sugars (45·7%) but low in calcium (1·94 g kg⁻¹), fibre content (4·6%) and essential amino acids. They had moderate functional properties. The rootlets were rich in calcium (19·9 g kg⁻¹) and in protein (31·9%), which had a good nutritive value (low in phytic acid and polyphenols content). They had a moderate fibre content (10·7%). Consequently, they had the highest water absorption, oil absorption and emulsification capacities. The rootlets had relatively low foam capacity but the highest foam stability. The husks were rich in fibre content (25%) but moderate in protein content (12·4%), which was rich in essential amino acids. The husks were relatively low in calcium (11·83 g kg⁻¹) and phosphorus (6·53 g kg⁻¹) contents and in vitro protein digestibility (68·9%). Their functional properties were influenced by high fibre and moderate protein contents. The first limiting amino acids were sulphur-containing ones in the malt sprouts, the acrospires and the rootlets, but it was leucine in the husks. © 1997 SCI.     

The glucosinolate content of the leaf and stem of fodder kale (Brassica oleracea L.), rape (Brassica napus L.) and radicole (Raphanobrassica)

The glucosinolate content of three fodder kales, one fodder rape, one semi-artificial rape and one radicole were determined. The major glucosinolates (mmol kg^?1 dry matter) were: in kale leaf, glucobrassicin (3.21) and sinigrin (3.12); in kale stem, sinigrin (5.82); in rape leaf, gluconapin (3.14) and progoitrin (13.99); in rape stem, gluconapin (3.29) and progoitrin (20.18); in semi-artificial rape leaf, gluconapin (25.64) and progoitrin (9.00); in semi-artificial rape stem, gluconapin (35.33) and progoitrin (12.08); in radicole leaf, progoitrin (4.74) and glucobrassicin (3.28); and in radicole stem, gluconapin (3.26) and progoitrin (5.53). The implications for plant breeding are discussed.     

Glucosinolates in brassica vegetables. Analysis of 22 varieties of brussels sprout (Brassica oleracea var. gemmifera)

The glucosinolate content of 22 cultivars of Brussels sprout have been determined. The levels of total glucosinolates, determined by methods based on glucose release and gas chromatography, were substantially higher than those reported by other workers for cabbage and Chinese cabbage. The major glucosinolates in Brussels sprout leaf material were identified as gluconapin, progoitrin, sinigrin and glucobrassicin, with the latter two generally predominating. Detailed analysis of the material from five different growing sites has shown considerable variation in the total content but surprisingly little difference in the relative proportions of the individual glucosinolates within each cultivar. The glucosinolates of the corresponding seed material differ significantly from that in leaf; in particular glucobrassicin is found in trace amounts only, and glucoerucin, glucotropaeolin and neoglucobrassicin are all present, in addition to sinigrin, progoitrin and gluconapin.     

Glucosinolate content of brassica vegetables: Analysis of twenty-four cultivars of calabrese (green sprouting broccoli,Brassica oleracea L. var. botrytis subvar. cymosa Lam.)

The contents of glucosinolates in twenty-four cultivars of calabrese, green sprouting broccoli, have been determined using glucose release and high performance liquid chromatographic methods. The levels of total glucosinolates (range, 42·1–94·5 mg 100 g⁻¹ fresh weight; mean, 62·3 mg 100 g⁻¹ fresh weight) were comparable with those reported previously for cauliflower, but lower than those found in cabbage and, especially, Brussels sprouts. Analysis of the individual components revealed the main species to be 4-methylsulphinylbutyl glucosinolate (glucoraphanin) and, particularly, glucobrassicin and neoglucobrassicin, containing 3-indolylmethyl and 1-methoxy-3-indolylmethyl side chains, respectively. The individual glucosinolate contents of calabrese and cauliflower are compared and differences are considered in the context of biosynthetic pathways. The consequences of these findings for the flavour and biological properties of calabrese are briefly discussed.     

In vitro protein digestibility and mineral availability of green beans (Phaseolus vulgarisL) as influenced by variety and pod size

Three varieties of green beans (Cleo, Strike and Sentry) were harvested and sorted into four fractions according to pod size (diameter <7 mm; 7–8·5 mm; 8·6–10 mm and >10 mm). Ash content and dietary fibre increased significantly as pod size increased mainly in Cleo and Strike beans. Strike showed the highest fibre content (378·0 g kg⁻¹) but the lowest carbohydrate (364·6 g kg⁻¹) and ash (68·4 g kg⁻¹) values. Mean values for Fe and Mg content were higher in Cleo beans (70·9 and 27·1 mg kg⁻¹, respectively), Zn, Cu and Mg were higher in Strike beans (48·7 mg kg⁻¹, 22·4 mg kg⁻¹ and 3·15 g kg⁻¹, respectively) while Na and Ca values were maximum in Sentry (459·1 mg kg⁻¹ and 7·11 g kg⁻¹, respectively). Trypsin inhibitor was negatively related to in vitro protein digestibility but no relationship was found between this last parameter and phytic acid content. This antinutrient, together with dietary fibre, and a negative influence on in vitro mineral dialysability of green beans. © 1998 SCI     

Rocket salad (Diplotaxis and Eruca spp.) sensory analysis and relation with glucosinolate and phenolic content

BACKGROUND: Salad crops of the Brassicaceae family, such as Diplotaxis tenuifolia and Eruca vesicaria, commonly referred to as ‘rocket salads’, have attracted considerable interest as culinary vegetables because of their strong flavour and their content of putative health‐promoting compounds. Among such compounds, glucosinolates and phenolics are well‐known phytochemicals with an important role also in determining the characteristic flavour of these species. In this study, to identify potentially high‐value rocket salads, 37 cultivated types were examined for sensory characters and their relations with glucosinolate and phenolic contents, which ranged from 0.76 to 3.03 g kg^?1 dry weight (DW) and from 4.68 to 31.39 g kg^?1 DW, respectively. RESULTS: The perception of bitter taste was significantly affected by specific glucosinolates, namely progoitrin/epiprogoitrin and dimeric glucosativin. Aroma intensity was negatively related to glucoalyssin content, whereas pungency was significantly related to total glucosinolate content. Kaempferol‐3‐(2‐sinapoyl‐glucoside)‐4′‐glucoside was positively and significantly related to all flavour trait perceptions. Aroma intensity, pungency, crunchiness and juiciness were positively related to typical rocket salad flavour perception through a prominent direct effect. CONCLUSION: Aroma intensity, pungency, crunchiness and juiciness were strong determinants of overall rocket salad flavour perception. Visual traits also characterised sensory components. Bitterness, usually considered a negative flavour trait, was moderately perceived in the examined material, without negatively affecting typical flavour perception. In the range of the examined material, glucosinolate content did not contrast with typical flavour, demonstrating that good taste and putative health‐promoting properties may coexist. Copyright © 2011 Society of Chemical Industry     

Wet Milling Comparison of Quality Protein Maize and Normal Maize

Quality protein maize (QPM) experimental hybrids and normal maize possessing different physical and chemical properties were studied as the raw material for wet milling. Maize samples were steeped for 36 h in a 600-ml solution containing 15 g kg⁻¹ lactic acid and 0·5 g kg⁻¹ SO₂ followed by 12 h in a second 600-ml solution containing 5 g kg⁻¹ lactic acid and 1 g kg⁻¹ SO₂. The steeped grain was then wet milled and the yields and purity of fractions were analysed. Water-soluble solids, kernel size, quality protein, total dietary fibre and ash content were higher in QPM samples than in normal maize. Water-soluble solids were positively correlated to kernel size ( r =0·97, P< 0·05), test weight ( r =0·83, P< 0·05) and density ( r =0·57, P< 0·05). Total fraction recovery for the five hybrids tested ranged from 921 to 955 g kg⁻¹, with the highest values corresponding to QPM hybrids. QPM hybrids yielded slightly higher starch content than normal maize. Gluten yields of QPM-HO (high oil) presented the highest values. The lysine contents of kernel, gluten and milling solubles were highest for QPM hybrids. QPM contained more palmitic acid than the other hybrids. The H-137 normal maize and QPM yellow dent-HO contained more oleic and linolenic acids than the other samples, and the QPM white-C (corneous) contained more linoleic acid than QPM-HO and normal maize.     

Chemical characterisation and ruminal nutrient degradability of hulled and hull-less oats

The objectives of this study were to determine the chemical and ruminal nutrient degradability characteristics of two hulled (Calibre and AC Mustang) and one hull-less (AC Belmont) oat varieties. Ruminal nutrient degradability characteristics of the oat varieties were determined relative to barley using one ruminally fistulated cow. Neutral (NDF) and acid (ADF) detergent fibre levels were higher (P < 0·05) in hulled than hull-less oats. Hulled AC Mustang had higher (P < 0·05) NDF and ADF content than hulled Calibre. Starch content was higher (P < 0·05) in AC Belmont (590 g kg⁻¹) than Calibre (457 g kg⁻¹) and was higher in Calibre than AC Mustang (415 g kg⁻¹). Crude protein was higher (P < 0·05) in hull-less than hulled oat. Both hulled varieties had similar CP content (average 124 g kg⁻¹). Estimated digestible energy value was highest (P < 0·05) for AC Belmont (16·94 MJ kg⁻¹), intermediate for Calibre (14·18 MJ kg⁻¹) and lowest for AC Mustang (13·34 MJ kg⁻¹). Ruminal dry matter and NDF degradability were higher (P < 0·05) in hull-less than barley and was higher in barley than hulled oats. Ruminal starch degradability exceeded 900 g kg⁻¹ for all tested feeds and had the order AC Belmont = barley > Calibre = AC Mustang. It was concluded that oat varieties used in this study varied considerably in their chemical composition and ruminal degradability. When compared with barley, hulled oats had lower while hull-less oats had higher ruminal degradability. © 1998 SCI.     

Heat treatment of Brussels sprouts retains their ability to induce detoxification enzyme expression in vitro and in vivo

Abstract: The bioactive metabolites of glucosinolates, such as isothiocyanates, contained in cruciferous vegetables have been shown to reduce the risk of cancers through the induction of detoxification enzymes. However, cruciferous vegetables are commonly processed before consumption, significantly altering the phytochemical composition of these vegetables. Compared to freeze‐dried Brussels sprouts, oven‐dried Brussels sprouts contain low concentrations of glucosinolates (22.14 and 0.85 μmol/g, respectively) and isothiocyanates (3.68 and 0.15 μmol/g, respectively). The effect of oven‐dried Brussels sprouts on the expression of detoxification enzymes was evaluated in vitro and in vivo. Treatment of immortalized human hepatoma cells with the aqueous extract from oven‐dried Brussels sprouts significantly increased quinone activity (0.5 and 1.5 mg/mL) and the activity of the antioxidant response element (EC50 = 2.39 mg/mL) and xenobiotic response element (EC50 2.92 mg/mL). C3H/HeJ mice fed a diet containing 20% oven‐dried Brussels sprout diets for 2 wk demonstrated significantly higher expression than animals fed a nutrient‐matched control diet of CYP1A1, CYP1A2, and epoxide hydrolase in the liver and CYP1A1, CYP1A2, CYP1B1, epoxide hydrolase, UGT1A1, thioredoxin reductase, and heme oxygenase in the lungs. The low concentrations of glucosinolates and isothiocyanates in oven‐dried Brussels sprouts suggest that other compounds, such as the Maillard reaction products that are produced during heating, are responsible for the induction of detoxification enzymes in vitro and in vivo. Practical Application: The manner in which cruciferous vegetables are processed prior to consumption has significant effects on what compounds people are exposed to. The presence of glucosinolates or isothiocyanates can be a good indicator of the ability of cruciferous vegetables to induce detoxification enzymes. However, the data presented here demonstrate that while heat processing of Brussels sprouts greatly reduced the concentrations of glucosinolates and isothiocyanates, their ability to induce detoxification enzymes in vitro and in vivo was retained.     

Identification of 1-cyano-2,3-epithiopropane in volatiles of a model system from brussels sprouts (Brassica Oleraceae L var Bullata subvar Gemmifera DC)

Volatiles produced in model systems consisting of a crude enzyme preparation from Brussels sprouts (Brassica oleraceae L var bullata subvar gemmifera DC), sinigrin, ascorbic acid and 2-mercaptoethanol were investigated using gas chromatography-mass spectroscopy. 2-Propen-1-yl isothiocyanate was the only breakdown product of sinigrin in the absence of 2-mercaptoethanol but in its presence 1-cyano-2,3-epithiopropane and small amounts of 2-propen-1-yl cyanide also were formed. The identification of the 1-cyano-2,3-epithiopropane was confirmed by comparison with a standard produced by autolysis of Crambe abyssinica L seed and with published mass spectra. The presence of 1-cyano-2,3-epithiopropane in volatile extracts of unblanched, frozen stored Brussels sprouts is also reported.     

Nutrient contents,rumen protein degradability and antinutritional factors in some colour- and white-flowering cultivars of Vicia faba beans

Six colour-flowering (Scirocco, Alfred, Carola, Condor, Tina and Herz Freya) and six white-flowering (Caspar, Albatros, Gloria, Tyrol, Vasco and Cresta) cultivars of Vicia faba were studied. The crude protein contents of colour- and white-flowering cultivars were 267±13·6 and 283±18·8 g kg⁻¹, respectively, which did not differ significantly at P<0·05. The levels of lipids, crude fibre, starch and ash varied from 14 to 22 g kg⁻¹, 88 to 143 g kg⁻¹, 407 to 485 g kg⁻¹ and 32 to 42 g kg⁻¹, respectively. The calculated organic matter digestibility (OMD) and metabolisable energy (ME) of the white-flowering cultivars were significantly higher (P<0·001) than those of the colour-flowering cultivars (OMD: 889·1±26·6 g kg⁻¹ vs 797·5±17·1 g kg⁻¹; ME: 13·97±0·49 vs 12·30±0·34 MJ kg⁻¹). In all cultivars, sulphur amino acids were lower than adequate concentration when compared with recommended amino acid pattern of FAO/WHO/UNO reference protein for a 2–5-year-old child. The in vitro rumen nitrogen degradability of colour-flowering cultivars was significantly lower (P<0·01) compared to that of white-flowering cultivars (71·4±9·3% vs 88·0±11·1%). Amongst colour-flowering varieties, the contents of total phenols (TP), tannins (T) and condensed tannins (CT) were highest in Alfred (28·3, 21·0 and 35·4 g kg⁻¹, respectively). The contents of TP and T were similar (about 15 and 10 g kg⁻¹, respectively) in Carola, Tina and Herz Freya, and the CT were in the order: Condor>Herz Freya>Carola. The CT were not detected in white-flowering varieties, T were virtually absent and TP were extremely low (4·0–4·9 g kg⁻¹). The activities of other antinutritional factors (white- and colour-flowering cultivars, respectively: trypsin inhibitor activity 3·05±0·34 and 1·85±0·09 mg trypsin inhibited g⁻¹; lectin 27·2±9·4 and 27·1±5·1 mg ml⁻¹ assay medium producing haemagglutination; phytate 15·0±2·7 and 16·6±2·3 g kg⁻¹) were very low. A strong negative correlation (r=-0·92, P<0·001) between tannins and in vitro rumen protein degradability was observed which suggested that tannins have adverse effect on protein degradability. Similarly negative correlations between tannin levels and metabolisable energy (r=-0·89; P<0·001) and organic matter digestibility (r=-0·89; P<0·001) were observed. The correlation coefficient between trypsin inhibitor activity and tannins was negative and highly significant (r=-0·88, P<0·001), whereas between tannins and saponins it was significantly positive (r=0·96, P<0·001). ©1997 SCI     

The effect of village processing techniques on the content of aflatoxins in corn and peanuts in Zambia

The effect of village processing techniques on the aflatoxin content of corn and peanut products was investigated. In 30 trials, corn kernels were dehulled (bran removal), soaked for 24 h, washed and dried before grinding into flour and boiling in water to a thick consistency (Nshima). Shelled peanuts were either dry-roasted as whole kernels or ground into peanut meal and cooked. Dehulling, following by 24-h soaking (steeping) and subsequent washing significantly (P<0·05) reduced the aflatoxin B₁ content of corn flour from 900 to 150 μg kg⁻¹, and similarly that of aflatoxin G₁ from 929 to 114 μg kg⁻¹. Preparation of Nshima did not result into a substantial reduction in aflatoxin content, neither did extension of the cooking duration of 2 h afford any further decontamination. Whereas boiling peanut meal yielded a moderate reduction in the content of aflatoxins B₁ and G₁, roasting whole peanut kernels greatly reduced (P<0·001) the concentrations of the toxins from that in raw kernels (AFB₁= 8600 μg kg⁻¹ and AFG₁=6200 μg kg⁻¹) to 1300 and 1200 μg kg⁻¹, respectively. These results indicate that specific processing techniques carried out in Zambian villages are effective in reducing aflatoxin carry-over into edible fractions, while others are not. © 1998 SCI.     

Purification of major glucosinolates from Brassicaceae seeds and preparation of isothiocyanate and amine metabolites

Consumption of Brassica vegetables containing glucosinolates is associated with decreased risk of cancer at several tissue sites. Studies of the relative potency and metabolism of the major dietary isothiocyanates have been hindered by limited availability of high‐purity isothiocyanates and their glucosinolate precursors. We describe a simple procedure for the preparation of glucosinolates sinigrin, gluconapin, progoitrin, glucoiberin, glucoraphanin, glucoalyssin and gluconasturtiin from vegetable seeds. Glucosinolates were extracted from the seeds of mustard, oilseed, broccoli, cauliflower and winter cress. Purification by preparative anion exchange and reversed‐phase column chromatography gave the pure glucosinolates. Good separation was achieved without using ion‐pair reagents. Related isothiocyanates and amine degradation products were prepared by myrosinase‐catalysed hydrolysis of the corresponding glucosinolate and by organic synthesis, respectively. The compounds were characterized by analytical HPLC, ¹H NMR, ¹³C NMR, elemental analysis and mass spectrometry. Optimized conditions for detection and quantitation of these glucosinolates and metabolites by LC‐MS/MS are also given. Large‐scale glucosinolate preparation could be performed, giving amounts suitable for pharmacological evaluation in vivo. These methods will facilitate studies of the pharmacological activity and metabolism of dietary glucosinolates. Copyright © 2006 Society of Chemical Industry     

Sensory quality of turnip greens and turnip tops grown in northwestern Spain

In Galicia (northwestern Spain), Brassica rapa var. rapa L. includes turnip greens and turnip tops as vegetable products that are characterized by a particular sulfurous aroma, pungent flavor, and a bitter taste. In this work, 12 local varieties grown as turnip greens and turnip tops were evaluated to define the sensory attributes, to relate them with secondary metabolites, and to select those sensorial traits that better describe these crops. Results showed differences in the sensory profiles of B. rapa varieties. Turnip greens were significantly different regarding aroma intensity, leaf color, and salty taste, while turnip tops were for color and firmness of leaves, moistness and fibrosity in mouth, sharpness, and bitter taste. Secondary metabolites as glucosinolates in turnip greens and phenolic compounds in turnip tops were highly correlated with texture and flavor. Glucosinolates, especially progoitrin (in turnip greens) and gluconapin (in turnip tops), showed correlation with bitter taste and aftertaste persistence. Correlation between sensory traits showed highest values between leaf firmness and stalk firmness (R = 0.94**), leaf firmness and fibrosity (R = 0.92**), aftertaste persistence and bitterness (R = 0.91**), and between bitterness and moistness (R = −0.89**).     

Dietary fibre content of thirteen apple cultivars

Fibre composition of the following 13 apple cultivars was studied: ‘Cortland’, ‘Empire’, ‘Fuji’, ‘Golden Delicious’, ‘Gala’, ‘Granny Smith’, ‘Jonagold’, ‘Mutsu’, ‘McIntosh’, ‘Delicious’, ‘Rome’, ‘Stayman’ and ‘York’. Fruit samples from each of these cultivars were analysed for non-starch cell wall materials (NSCWM) and non-starch polysaccharides (NSP). NSCWM was further fractionated into soluble and insoluble fibre fractions. Both NSCWM and NSP content were found to be significantly influenced by cultivar. NSCWM content ranged from 19·1 g kg⁻¹ apple flesh in ‘Fuji’ to 36·2 g kg⁻¹ in ‘York’. Mean(±SD) NSCWM content of all the cultivars was 23·1±4·5 g kg⁻¹. NSP content of apple flesh ranged from 13·8 g kg⁻¹ in ‘McIntosh’ to 28·7 g kg⁻¹ in ‘York’ with the overall mean for all cultivars being 17·9±4·2 g kg⁻¹. Relative amount of monosaccharides found in the hydrolysates of apple fibre also varied among cultivars. The greatest difference was observed in galactose content. ©1997 SCI     

Induction of Detoxification Enzymes by Feeding Unblanched Brussels Sprouts Containing Active Myrosinase to Mice for 2 Wk

Abstract: In cruciferous vegetables, myrosinase metabolizes the relatively inactive glucosinolates into isothiocyanates and other products that have the ability to increase detoxification enzyme expression. Thus, maintaining myrosinase activity during food preparation may be critical to receiving the maximum benefit of consumption of Brussels sprouts or other cruciferous vegetables. To test the importance of maintaining myrosinase activity for maximizing bioactivity, experimental diets containing 20% unblanched (active myrosinase) or 20% blanched (inactivated myrosinase) freeze-dried Brussels sprouts and a nutrient-matched control diet were evaluated in vitro and in vivo for their ability to induce detoxification enzymes. Treatment of immortalized HepG2 human hepatoma cells with the unblanched Brussels sprout diet caused a greater increase quinone activity compared to the blanched Brussels sprout diet. C3H/HeJ mice fed the unblanched Brussels sprout diets for 2 wk had significantly higher plasma sulforaphane concentrations. Liver expression of CYP1A1 and epoxide hydrolase, measured using real-time PCR, was correlated with the plasma concentration of sulforaphane. In the lung, expression of epoxide hydrolase, thioredoxin reductase, UDP glucuronosyltransferase, quinone reductase, heme oxygenase, CYP1A1, CYP1A2, and CYP1B1 were also correlated with the plasma concentration of sulforaphane. Together these data demonstrate that, as predicted by the in vitro experiment, in vivo exposure to Brussels sprouts with active myrosinase resulted in greater induction of both phase I and phase II detoxification enzymes in the liver and the lungs that correlated with plasma sulforaphane concentrations.     

Effects of intraruminal infusions of propionate and butyrate with two different protein supplements on milk production and blood metabolites in dairy cows receiving grass silage-based diet

Four cows were used in a balanced 4×4 Latin square with 2 week experimental periods to investigate the effects of intraruminal infusions of volatile fatty acids and protein source on milk production and blood metabolites. The four treatments in a 2×2 factorial arrangement were isoenergetic intraruminal infusions of propionate (500 g day⁻¹) or butyrate (417 g day⁻¹) each given with isonitrogenous protein supplementation of fish meal (FM) or barley protein (BP). The cows were fed restrictively with 9 kg dry matter day⁻¹ of formic acid treated grass silage and 8 kg day⁻¹ of concentrate. Propionate infusion increased milk yield (24·9 vs 23·4 kg day⁻¹; P<0·05), milk protein yield (832 vs 778 g day⁻¹; P=0·05) and milk lactose content (44·7 vs 43·5 g kg⁻¹; P<0·05) and yield (1113 vs 1023 g day⁻¹; P<0·01), whereas butyrate infusion was associated with a higher milk fat content (44·7 vs 39·4 g kg⁻¹; P<0·01) and yield (1033 vs 974 g day⁻¹; P<0·01). FM tended (P<0·10) to increase milk yield, but had no significant effects on milk composition or milk component yields compared with BP. Butyrate infusion increased blood ketones, plasma non-esterified fatty acids and glycine relative to propionate infusion. The concentrations of ammonia N in rumen fluid and urea in plasma and milk were similar for both protein supplements. The profile of amino acids in plasma was similar for both protein supplements except for the higher concentrations of phenylalanine, proline and tyrosine with BP. The results show that protein utilisation can be improved by increasing the supply of propionate from rumen fermentation in cows given a grass silage-based diet. © 1998 SCI.     

Comparison of HPLC and GLC methodologies for determination of glucosinolates using reference material

 The reference material rapeseed of known glucosinolate composition, was analysed by HPLC and GLC and two commercially available glucosinolates (glucotropaeolin and sinigrin) were used as internal standards. The HPLC method enabled determination of 11 different glucosinolates (as desulphoglucosinolates) that occur in the rapeseed. Only seven glucosinolates (as trimethylsilylated desulphoglucosinolates) were separated by GLC. The latter method did not allow the determination of methylsulphinylalkyl glucosinolates (glucoiberin, glucoraphanin and glucoallysin) and did not separate optical isomers of 2-hydroxy-3-butenyl glucosinolate (progoitrin and epi-progoitrin). Statistical evaluation of data (t-test, F-test) revealed no significant differences between the tested methods at the 95% confidence level. The advantages and disadvantages of both widely used chromatographic methods are discussed. Received: 26 May 1997 / Revised version: 11 July 1997     

Glucosinolates in Brassica vegetables. Analysis of twenty-seven cauliflower cultivars (Brassica oleracea L. var. botrytis subvar. cauliflora DC)

The glucosinolate content of 27 cultivars of commercially grown cauliflower have been determined. The levels of total glucosinolates (<120 mg 100 g^?1 fresh wt) were comparable with those previously reported for cabbage, but much lower than those found in Brussels sprouts. The major individual glucosinolates were identified as those possessing prop-2-enyl-, 3-methylsulphinylpropyl-, 3-indolylmethyl- and 1-methoxy-3-indolylmethyl- side chains. Smaller amounts of but-3-enyl-, 2-hydroxybut-3-enyl-, 3-methylthiopropyl-, 4-methylthiobutyl-, 2-phenylethyl-, pent-4-enyl-, 2-hydroxypent-4-enyl- and 5-methylthiopentyl-glucosinolates were also measured in some cultivars, the last three compounds not previously having been reported in cauliflower. Environmental effects, determined for the cultivars Wallaby, Coolabah, Barrier Reef and Snowy River were much less than previously found in Brussels sprouts.