CHEMICAL AND SENSORY QUALITY OF BROCCOLI (BRASSICA OLERACEA L. VAR ITALICA)

Five cultivars of broccoli (Brassica oleracea L. var. italica) were analyzed for individual glucosinolates, S-methylcysteine sulfoxide (SMCSO), aroma volatiles and sensory quality. Total glucosinolate content ranged from 47 to 93 μmol μmol·g dry weight¹, and SMCSO ranged from 22 to 57 μmol μmol·g dry weight¹. A total of 11 glucosinolates were identified in the broccoli cultivars. The major glucosinolates were: progoitrin, glucoiberin, glucoraphanin, glucobrassicin and neo-glucobrassicin and they accounted for more than 95% of the total content. Glucoiberin was only found in appreciable amounts in purple-headed broccoli. Pentanol, pentanal, hexanal, heptanal and nonanal were the most abundant higher boiling volatiles isolated from cooked broccoli using dynamic headspace trapping on Porapak and solvent desorption with diethyl ether. Sensory analysis by a trained panel showed that scores for cooked vegetable odor (‘hay’ and ‘green peapod’) were significantly different between cultivars. In contrast, scores related to Brassica odor (‘cauliflower’ and ‘mustard’) were not significantly different. The content of individual glucosinolates, SMCSO and higher boiling volatiles in the cultivars is discussed in relation to the sensory quality of the cooked product.     

Total and individual glucosinolate contents in inflorescences of eight broccoli cultivars grown under various climatic and fertilisation conditions

Total aliphatic, indolic and aromatic glucosinolates were evaluated in the edible portions of fresh harvested inflorescences of five commercial and three experimental broccoli (Brassica oleracea L var italica) cultivars grown under various climatic and agronomic conditions, ie early (winter) or late (spring) season with poor (15 kg ha^?1) or rich (150 kg ha^?1) sulphur fertilisation, in an attempt to identify differences due to genetic and agronomic factors. The predominant glucosinolates in all broccoli cultivars were 4‐methylsulphinylbutyl‐glucosinolate (glucoraphanin), 3‐indolylmethyl‐glucosinolate (glucobrassicin) and 1‐methoxy‐3‐indolylmethyl‐glucosinolate (neoglucobrassicin). The results showed no significance differences in total glucosinolates between rich and poor fertilisation, whereas total glucosinolates were detected more significantly in the late than in the early season. All broccoli cultivars showed a higher content of indolic glucosinolates than aliphatic glucosinolates. Clear advantages were detected in the analysed commercial cultivars, as the experimental cultivars yielded lower concentrations of these compounds. © 2003 Society of Chemical Industry     

Potential bioactive compounds in health promotion from broccoli cultivars grown in Spain

Glucosinolates, phenolic compounds and vitamin C were evaluated in two commercial and 12 experimental cultivars of broccoli (Brassica oleracea L var italica) grown under uniform cultural conditions. The predominant glucosinolates in all broccoli cultivars were 4‐methylsulphinylbutyl glucosinolate (glucoraphanin) and 3‐indolylmethyl glucosinolate (glucobrassicin). Other glucosinolates such as 4‐OH‐glucobrassicin and N‐methoxyglucobrassicin were detected in lower amounts. The total glucosinolate concentration ranged from 3.0 µmol g^?1 dw (dry weight) in Pentathlon (experimental cultivar) to 28.3 µmol g^?1 dw in I‐9905 (experimental cultivar). Flavonoids, caffeic acid derivatives and sinapic acid derivatives were quantified in methanol extracts. The largest content of flavonoids was found in the commercial cultivars Marathon and Lord, around 60 mg kg^?1 fw (fresh weight). The vitamin C content of broccoli ranged from 43.1 mg per 100 g fw in Lord (commercial cultivar) to 146.3 mg per 100 g fw in SG‐4515 (experimental cultivar). © 2002 Society of Chemical Industry     

Consumer Acceptability and Sensory Profile of Cooked Broccoli with Mustard Seeds Added to Improve Chemoprotective Properties

Broccoli, a rich source of glucosinolates, is a commonly consumed vegetable of the Brassica family. Hydrolysis products of glucosinolates, isothiocyanates, have been associated with health benefits and contribute to the flavor of Brassica. However, boiling broccoli causes the myrosinase enzyme needed for hydrolysis to denature. In order to ensure hydrolysis, broccoli must either be mildly cooked or active sources of myrosinase, such as mustard seed powder, can be added postcooking. In this study, samples of broccoli were prepared in 6 different ways; standard boiling, standard boiling followed by the addition of mustard seeds, sous vide cooking at low temperature (70 °C) and sous vide cooking at higher temperature (100 °C) and sous vide cooking at higher temperature followed by the addition of mustard seeds at 2 different concentrations. The majority of consumers disliked the mildly cooked broccoli samples (70 °C, 12 min, sous vide) which had a hard and stringy texture. The highest mean consumer liking was for standard boiled samples (100 °C, 7 min). Addition of 1% mustard seed powder developed sensory attributes, such as pungency, burning sensation, mustard odor, and flavor. One cluster of consumers (32%) found mustard seeds to be a good complement to cooked broccoli; however, the majority disliked the mustard‐derived sensory attributes. Where the mustard seeds were partially processed, doubling the addition to 2% led to only the same level of mustard and pungent flavors as 1% unprocessed seeds, and mean consumer liking remained unaltered. This suggests that optimization of the addition level of partially processed mustard seeds may be a route to enhance bioactivity of cooked broccoli without compromising consumer acceptability.     

Influence of blanching and freezing broccoli (<Emphasis Type="Italic">Brassica oleracea</Emphasis> var. <Emphasis Type="Italic">italica</Emphasis>) prior to storage and cooking on glucosinolate concentrations and myrosinase activity

Glucosinolates contribute to the chemoprotective effects of Brassica vegetables. The influence of blanching and freezing broccoli, followed by storage or cooking, on its glucosinolate concentration and myrosinase activity was investigated. Myrosinase activity was reduced by 93%, while glucosinolate concentration was unaltered after blanch-freezing broccoli. Blanch-frozen Brassica retained the glucosinolate content of its fresh counterpart after storage at T = −20 °C for up to 90 days. Fresh or blanch-frozen broccoli was stir-fried, boiled, boiled and kept hot for 2 h, or left uncooked. Stir-frying retained the highest glucosinolate concentration and myrosinase activity, regardless of pre-cooking. Boiling and keeping blanch-frozen broccoli hot completely denatured myrosinase and decreased glucosinolate concentration by 42%. Aromatic and indole glucosinolates were reduced to a larger extent than aliphatic glucosinolates, especially when boiled broccoli was kept hot. The final concentration of glucosinolates in Brassica is influenced by cooking, while the myrosinase activity is modified by pre-treatment and subsequent cooking.     

ASSESSMENT OF GLUCOSINOLATES IN BROCCOLI BY THREE DIFFERENT METHODOLOGIES

ABSTRACT Three different methodologies were used to assess the glucosinolate content in four broccoli cultivars. The assessment was performed by the thymol, enzyme immobilization and gas liquid chromatography (GLC) techniques. The cultivars used were Green Valiant, Green Duke, Marathon and Samurai. The three techniques demonstrated that Samurai and Green Valiant were the cultivars with the highest content of glucosinolates. It was also evident that, compared to stem and leaves, the floret of the four cultivars exhibited in general the highest amount of this component. Of the tested methodologies, the GLC technique showed the lowest data variability, although this technique was unable to estimate all the glucosinolates present in the broccoli samples because of its poor performance for the quantitation of indole and sulfinyl glucosinolates. In conclusion, the thymol technique appeared the most adequate procedure for the assessment of glucosinolates in broccoli samples.     

Genotypic variation of glucosinolates in broccoli (Brassica oleracea var. italica) florets from China

Five main cultivars from China and 143 parent materials grown in a greenhouse were used to investigate the glucosinolates in broccoli florets. Eight aliphatic glucosinolates, four indole glucosinolates, and one aromatic glucosinolate were identified and quantified using high-performance liquid chromatography (HPLC). The results showed that glucoraphanin, glucobrassicin, 4-methoxyglucobrassicin and neoglucobrassicin were present in all samples. However, the predominant type of glucosinolate was different among pure lines. The anti-cancer glucoraphanin concentration ranged from 0.06 to 24.17 μmol/g in pure lines and from 1.57 to 5.95 μmol/g in commercial cultivars. The progoitrin concentration in commercial cultivars varied from 1.77 to 6.07 μmol/g with a mean value of 3.20 μmol/g. Significant variations were observed in the concentration of individual glucosinolates and in each class of glucosinolates among broccoli populations. Dozens of specific lines with altered glucosinolate profiles, as well as ten good candidates for breeding high-chemoprotective glucosinolate cultivars, were obtained according to the putative glucosinolate pathway in broccoli.