Effect of thermal treatment on glucosinolates and antioxidant-related parameters in red cabbage (Brassica oleracea L. ssp. capitata f. rubra)

The effects of various thermal processing treatments (blanching, boiling and steaming) of red cabbage, Brassica oleracea L. ssp. capitata f. rubra cv. ‘Autoro’, were assessed for the levels of glucosinolates (GLS), total phenols (TP), total monomeric anthocyanins (TMA), l-ascorbic acid (L-AA) and soluble sugars, as well as for the antioxidant potential by the ferric reducing ability power (FRAP) and oxygen radical absorbance capacity (ORAC) assays. Individual native GLS were determined by ion-pair HPLC-MS/DAD. There were significant (p < 0.05) losses in blanched red cabbage: TP, 43%, TMA 59%, FRAP 42%, ORAC 51%, L-AA 48% and soluble sugars 45%. Boiling gave less extensive reductions: TP 16%, TMA 41%, FRAP 17%, ORAC 19%, L-AA 24% and soluble sugars 19%. Steaming caused no losses for TP, ORAC, FRAP or soluble sugars. However, significant reductions were found for TMA and L-AA, with 29% and 11%, respectively. In general losses were accounted for in the processing waters; however, TMA was not fully recovered, indicating degradation. Total GLS were severely affected by processing, with reductions of 64%, 38% and 19% in blanched, boiled and steamed red cabbage, respectively. Total aliphatic and indole GLS were similarly affected. Lost GLS were partially recovered in the processing water.     

Analysis and metabolite profiling of glucosinolates,anthocyanins and free amino acids in inbred lines of green and red cabbage (Brassica oleracea L.)

We profiled and quantified glucosinolates (GSLs), anthocyanins and free amino acids in thirty-seven inbred lines green and red cabbage. Analysis of these distinct cabbages revealed the presence of 8 GSLs, 13 anthocyanins and 12 free amino acids. GSL contents were varied among the different lines of cabbage. The maximum levels of glucoraphanin (14.91 μmol/g DW) and glucobrassicin (12.37) were found in FX 1-28 and FX 1-32 lines, respectively. Total GSLs in red cabbage lines were 50% higher than those of green cabbage. Anthocyanin contents in red cabbage were ranged from 4.11 to 6.81 mg/g DW in FX 2-3 and FX 1-34 lines, respectively. Among the 13 anthocyanins, both cyanidin 3-(feruloyl) (sinapoyl)diglucoside-5-glucoside and cyanidin 3-(sinapoyl) (sinapoyl)diglucoside-5-glucoside levels were the highest amounts. The amounts of total free amino acids were ranged from 523.5 to 1308 mg/100 g fresh weight (FW) in green cabbage and 484.8 to 1271 in red cabbage, respectively. In red cabbage lines, 9.4% of the total free amino acids accounted essential amino acids such as valine, threonine, isoleucine, leucine and lysine. Thus, the amounts of GSLs, anthocyanins, and amino acids varied widely, and the variations in these compounds between the lines of cabbage were significant.     

Partial characterization of white cabbages (Brassica oleracea var. capitata f. alba) from different regions by glucosinolates, bioactive compounds, total antioxidant activities and proteins

Glucosinolates (GLS), antioxidative compounds, total radical scavenging activities (TRSAs) and proteins of white cabbage samples derived from different regions of Europe, collected in the spring and autumn, were studied. Glucobrassicin and sinigrin were the dominating GLS in all analyzed cabbage samples. Depending on origin, these two GLS accounted for ∼30% to ∼70% of the total. The total GLS content ranged from 3.3 to 7.7 μmol/g dw in lyophilized vegetables. Assays based on electron transfer [total phenols by Folin-Ciocalteu reagent (FCR), 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid)] radical cation (ABTS) and 1,1-diphenyl-2-picrylhydrazyl (DPPH)] were used to compare the TRSAs and the main bioactive compounds in cabbage. Total polyphenols varied from 2.4 to 4.9 GAE/g dw. The TRSAs ranged from 2.7 to 8.2 μmol TE/g dw in ABTS test and from 2.4 to 5.4 μmol TE/g dw in DPPH assay. The maximum amount of polyphenol compounds, antioxidant activity, as well as total GLS content, were recorded in Belgian cabbage harvested in the autumn and the lowest ones were found for Poland 2 cabbage harvested in the spring. In extracted and separated by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) proteins from cabbage leaves only in samples from England and Belgium some differences in patterns were found in the regions of 60 and 97 kDa. The calculated correlations between antioxidative potency and the abundance of bioactive compounds were highly statistically significant. This suggests that TRSA could serve as a means of standardization of natural mixtures, at least in the case of cabbage, necessary to compare results of biological studies carried out for vegetable derived samples.     

Processing (blanching, boiling, steaming) effects on the content of glucosinolates and antioxidant-related parameters in cauliflower (Brassica oleracea L. ssp. botrytis)

Five different varieties of cauliflower (Brassica oleracea L. ssp. botrytis); two white (cv. ‘Aviso’, ‘Dania’), one purple (cv. ‘Grafitti’), one green (cv. ‘Emeraude’) and one romanesco/green pyramidal (cv. ‘Celio’) cultivar have been studied. All samples were thermally processed and the effects on the levels of glucosinolates (GLS), total phenols (TP), total monomeric anthocyanins (TMA), l-ascorbic acid (l-AA) and antioxidant capacities (FRAP and ORAC) were investigated. Processing methods applied were: blanching (3 min), boiling (10 min) and steaming (10 min). Total GLS were significantly (p < 0.05) affected by processing with the highest losses, 55 and 42% on average, occurring for boiled and blanched samples, respectively. Significant effects were also noted for steaming, but to a lesser extent, i.e. 19% average reduction. Antioxidant-related parameters were similarly affected with average losses of 27, 33, 36 and 46% in boiled cauliflower and 16, 21, 22 and 28% in blanched for TP, FRAP, l-AA and ORAC, respectively. Blanching and boiling reduced TMA in purple cauliflower by 38 and 53%, respectively. Steaming affected the antioxidant-related parameters the least for all cultivars. l-AA was significantly reduced by 14% in all cultivars by steaming. Some differences in behaviour between cultivars were noted, especially between white and coloured cultivars for TP, FRAP and l-AA, but also for some GLS. The main losses were caused by leaching into the processing water.     

Effect of water content and temperature on glucosinolate degradation kinetics in broccoli (Brassica oleracea var. italica)

The effect of water content and temperature on glucosinolate thermal degradation in broccoli (Brassica oleracea var. italica) was investigated. Broccoli was freeze dried obtaining batches with water content between 13% and 82% (a_w from 0.32 to 0.99). These samples were heated at different temperatures (from 60 to 120 °C) and glucosinolate levels were monitored. To rule out enzymatic breakdown, myrosinase was inactivated prior to heating. Degradation could be described by first-order kinetics for all glucosinolates and all water contents. In the temperature range 60–100 °C the sample with 13% showed the lowest degradation rate, whereas at 120 °C the degradation rate increased with the water content. This particular behavior was reflected by the high activation energy value of the driest sample. Several hypotheses to explain the observed behavior are discussed.     

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.     

Glucosinolates, l-ascorbic acid,total phenols,anthocyanins, antioxidant capacities and colour in cauliflower (Brassica oleracea L. ssp. botrytis); effects of long-term freezer storage

Blanching and one year freezer storage were performed on one purple, two white and two green varieties of cauliflower (Brassica oleracea L. ssp. botrytis) to assess the effects on several health-related phytochemicals. Blanching, prior to freezing, reduced total aliphatic and indole glucosinolates (GLS) by 31% and 37%, respectively. l-ascorbic acid (L-AA), total phenols (TP), anthocyanins, FRAP and ORAC were on average reduced by 19, 15, 38, 16 and 28%, respectively. The colour measured as CIELAB parameters was partly affected by blanching: lightness was significantly reduced in the white cultivars and in a romanesco type cultivar. Chromaticity was reduced in the coloured cultivars with a twice-as-large reduction in the purple cultivars. Hue increased for all samples, except for the purple cultivar where a decrease was found. Long-term freezer storage did not affect total aliphatic and indole GLS in cauliflower in a major way. Freezer storage did result in an average L-AA decrease of 24% for all but the purple cultivar. Some reductions in the TP levels were also found but not to the extent found for L-AA. When an effect was found in the FRAP and ORAC values, the reductions occurred towards the end of the storage period and were 15% and 37%, on average, respectively. Long-term freezer storage did not affect the anthocyanin content and only minor effects were found for the colour parameters.     

Variation of glucosinolates in 62 varieties of Chinese cabbage (Brassica rapa L. ssp. pekinensis) and their antioxidant activity

Glucosinolate (GSL) and antioxidant activity in 62 varieties of Chinese cabbage (Brassica rapa L. ssp. pekinensis) were determined by HPLC and DPPH, HRSA, and FRAP assays. Five aliphatic GSLs: progoitrin, sinigrin, glucoalyssin, gluconapin, and glucobrassicanapin; four indolyl GSLs: 4-hydroxyglucobrassicin, glucobrassicin, 4-methoxyglucobrassicin, and neoglucobrassicin; one aromatic GSL: gluconasturtiin were identified. Glucobrassicanapin and gluconapin documented the most abundant (average 4.52 and 3.72 μmol/g DW, respectively). The contents of total GSLs varied extensively among 62 varieties (range from 2.83 to 48.53 μmol/g DW). Comprehensive differences in total and individual GSL contents have also been observed among different varieties. Indolyl and aromatic GSL together accounted 26% of the total GSLs; but there are few differences among varieties. FC7 and FI17 could be good candidates for future breeding programs since they had a high quantity of glucobrassicin (2.10 and 1.66 μmol/g DW, respectively). Most of the Chinese cabbage varieties showed significant antioxidant activities when compare with positive control. However, three antioxidant assays were not significantly correlated with total GSLs. The presence of significant quantities of glucobrassicin in some varieties should be studied more extensively, since GSL is the precursor of indole-3-carbinol, a potent anticancer isothiocyanate.     

Glucosinolates profile of Brassica rapa L. subsp. Sylvestris L. Janch. var. esculenta Hort

Glucosinolates in different ecotypes of Brassica rapa L. subsp. sylvestris L. Janch. var. esculenta Hort. widely distributed in Southern Italy and locally known as “friariello” and “cima di rapa”, were characterized and their glucosinolate composition was compared with that of broccoli (Brassica oleracea L. var. italica).     

Characterisation of the pigment components in red cabbage (Brassica oleracea L. var.) juice and their anti-inflammatory effects on LPS-stimulated murine splenocytes

To determine anti-inflammatory effects of pigments from red cabbage, red cabbage (Brassica oleracea L. var.) juice was prepared, characterized by UV–vis absorption spectra, partially purified by Sephadex LH-20 column, analyzed by HPLC, and administered to lipopolysaccharide (LPS)-stimulated murine splenocyte cultures. The study showed that red cabbage juice (RC) exhibited anti-inflammatory effects against LPS-induced inflammation of splenocytes via increasing anti-inflammatory cytokine interleukin (IL)-10 and decreasing pro-inflammatory cytokine IL-6 secretions. The maximum absorption peaks of RC and its heated products, but not activated charcoal-adsorbed products, appeared at 280 nm with a small shoulder around 310–330 nm while there existed a minor peak at 560 nm (range from 480 to 630 nm), reflecting red cabbage juice included phenolics, flavonoids, and anthocyanins. The lyophilized powder of chromatographic fractions F2, F3, and F4 through Sephadex LH-20 column were rich in phenolics (5.9 ± 0.2%, 4.4 ± 0.0%, and 3.9 ± 0.0%, respectively) and flavonoids (1.8 ± 0.3%, 1.8 ± 0.3%, and 1.1 ± 0.3%, respectively). The results suggest that anti-inflammatory pigment compounds in red cabbage juice were heat stable. Further analysis of chromatograms from HPLC suggests malvidin glycosides including malvidin 3-glucoside (oenin), malvidin 5-glucoside and malvidin 3,5-diglucoside in red cabbage juice could inhibit IL-6 secretion of LPS-stimulated splenocytes.     

Nutrient contents of kale (Brassica oleraceae L. var. acephala DC.)

Fructose, glucose and sucrose, as the major soluble sugars and citric and malic acids, as the major organic acids, were identified and determined in kale (Brassica oleraceae L. var. acephala DC., black cabbage) leaves. Fructose was the predominant sugar (2011 mg 100 g⁻¹ dry wt) identified, followed by glucose (1056 mg 100 g⁻¹ dry wt) and sucrose (894 mg 100 g⁻¹ dry wt). The contents of citric and malic acids were at 2213 and 151 mg 100 g⁻¹ dry wt in the leaves. The 16:0, 18:2n − 6 and 18:3n − 3 fatty acids were the most abundant fatty acids in the leaves. Considering the level of these fatty acids, 18:3n − 3 was found to be the highest (85.3 μg g⁻¹ dry wt), contributing 54.0% of the total fatty acid content. Linoleic acid (18:2n − 6), being the second most abundant fatty acid was present at 18.6 μg g⁻¹ dry wt, contributing 11.8% of the total fatty acid content. In the seed oil of kale, 22:1n − 9 was the most abundant fatty acid (4198 μg g⁻¹ dry wt, 45.7%), with 18:2n − 6 (1199 μg g⁻¹ dry wt, 12.3%) and 18:1n − 9 (1408 μg g⁻¹ dry wt, 14.8%) being the second next most abundant fatty acids. The most abundant amino acid was glutamic acid (Glu) which was present at 33.2 mg g⁻¹ dry wt. Aspartic acid, which was the second most abundant amino acid, was present at 27.6 mg g⁻¹ dry wt and accounted for 10.2% of the total amino acid content of kale leaf. The amino acid content was assessed by comparing the percentages of the essential amino acids in kale leaf versus those of a World Health Organization (WHO) standard protein. The protein of kale leaf compares well with that of the WHO standard. Only one amino acid, lysine, had a score that fell below 100%; the lysine score of kale leaf was 95%. This study attempts to contribute to knowledge of the nutritional properties of the plant. These results may be useful for the evaluation of dietary information.     

西兰花茎叶肽的酶法制备及其降血脂功能研究

本文以西兰花茎叶为原料,用煮沸法从中提取蛋白。蛋白粗提物经酶解制备,得到西兰花肽后用Valflow50超滤、Sephadex G-15分离纯化,通过细胞实验进行降血脂功能筛选,最后通过动物实验对其降血脂功能进行评价。结果表明,西兰花蛋白粗提物的蛋白质含量为49.6%,酶解可以增强西兰花蛋白的降血脂活性,分离组分G15-Ⅱ的体外降血脂功能最强。以400、200 mg/kg灌胃的大鼠血液总胆固醇(TC)和甘油三酯(TG)含量水平降低(P<0.01),同时400 mg/kg组的HDL-C含量提高(P<0.05),表明G15-Ⅱ具有降血脂作用。此研究可为西兰花的深度开发和综合利用提供基础数据和科学参考。     

Changes in carbohydrate and glucosinolate composition in white cabbage (Brassica oleracea var. capitata) during blanching and treatment with acetic acid

The effect of blanching and treatment with white vinegar containing acetic acid on dietary fibre, low-molecular-weight carbohydrates and glucosinolates was studied in two cultivars of white cabbage (Heckla and Predikant). The total content of dietary fibre and low-molecular-weight carbohydrates was similar in both cultivars (24 and 60 g/100 g DM, respectively), while the distribution between soluble and insoluble fibre differed (19% was soluble in Heckla versus 26% in Predikant, P < 0.01). Further, Heckla contained higher amounts of glucose and sucrose, while the content of fructose and total glucosinolates was lower than in Predikant. The content of individual glucosinolates differed between the two cultivars. During blanching there was a loss of dry substance (30–34 g/100 g DM), where low-molecular-weight carbohydrates primarily explained the loss (82–90%), but some of the loss was also dietary fibre (about 8%), both soluble fibre containing uronic acids (mainly Predikant) and insoluble ones containing glucose (mainly Heckla). The glucosinolate levels decreased substantially in both cultivars, although the total loss was higher in Predikant (74%) than in Heckla (50%). The individual glucosinolates were affected to different degrees (15–91%). During souring with acetic acid, the content of dietary fibre (primarily insoluble ones) decreased further, while the content of low-molecular-weight carbohydrates was less affected. The total content of glucosinolates was not affected in Heckla but was further reduced in Predikant. There was, however, a substantial increase in 4-methoxyglucobrassicin in both cultivars. It is concluded that blanching and souring decrease the content of carbohydrates and glucosinolates to a great extent and both cultivars behaved similarly. However, individual components were affected differently in the two cultivars.     

Antioxidant activity and phenolic compounds of fractions from Portulaca oleracea L.

Portulaca oleracea fractions obtained from the crude extract of the plant by reversed-phase separation were investigated for their antioxidant activities and phenolic compounds content. Five fractions were classified based on optical absorption between the wavelength range of 200–400 nm. Fraction 3 displayed higher absorption than the other fractions. The total amount of quantified phenolics in this fraction was found to be quite high compared to that of crude extract. Chlorogenic, caffeic, p-coumaric, ferulic and rosmarinic acids were the free phenolic acids, and quercetin and kaempferol were the free flavonoids detected in Fraction 3. IC₅₀ value of crude extract was found to be 511.8 μg/ml whereas Fraction 3 exhibited an IC₅₀ value of 154.1 μg/ml. TEAC of Fraction 3 was found to be almost four times higher than that of the crude extract. Fraction 3 was also found to show the highest lipid peroxidation inhibiting capacity, determined by TBARS assay.     

Anthocyanin composition of cauliflower (Brassica oleracea L. var. botrytis) and cabbage (B. oleracea L. var. capitata) and its stability in relation to thermal treatments

Violet cauliflower and red cabbage were analysed for their anthocyanin profiles before and after thermal treatments. Anthocyanins are well-noted as healthy compounds due to their antioxidant properties. Samples were analysed for total anthocyanin content by using a spectrophotometric differential pH method. An MS-based method, combining high-performance liquid chromatography (HPLC) with quadrupole tandem mass spectrometry (HPLC–MS/MS) was developed, aimed to separate, identify and quantify the main anthocyanin forms. The procedure involves a rapid and efficient pre-treatment of the samples by solid-phase extraction, followed by selective determination of all compounds in a single run analysis using HPLC–MS/MS. Structural information for the identification of compounds was obtained from their fragmentation patterns (MS/MS spectra). The compounds were separated by HPLC and detected in the multiple reaction monitoring mode (MRM), which provides a high level of selectivity for targeting the analytes in vegetables. Cauliflower and red cabbage showed differences in their anthocyanin profiles: cyanidin-3,5-diglucoside was absent in cauliflower, while it was well represented in red cabbage, together with the characteristic anthocyanin of Brassica genus, cyanidin-3-sophoroside-5-glucoside. The p-coumaryl and feruloyl esterified forms of cyanidin-3-sophoroside-5-glucoside were predominant in cauliflower, while the sinapyl one was mostly present in red cabbage. Besides, the stability of cauliflower’s anthocyanin profile was evaluated in relation to thermal pre-treatments. All thermal treatments, except microwave heating, drastically reduced total cauliflower anthocyanin content. The amount of individual anthocyanins was expressed as the percentage with respect to total anthocyanin amount, spectrophotometrically measured. Significant individual changes were observed after different thermal treatment with an isomer formation.     

Impact of different drying trajectories on degradation of nutritional compounds in broccoli (Brassica oleracea var. italica)

This work concerns the degradation of the nutritional compounds glucoraphanin (GR) and vitamin C (Vc), and the inactivation of the enzyme myrosinase (MYR) in broccoli (Brassica oleracea var. italica) during drying with air temperatures in the range of 30–60 °C. Dynamic optimization is applied to find the optimized temperature trajectories that minimize degradation and inactivation. Simulation and experimental results for optimized temperature trajectories are compared to constant inlet air temperature drying at 40 and 50 °C. The results show that with the optimized temperature trajectories the retention of GR, MYR and Vc improved significantly. Moreover, the experiments show that degradation and inactivation during drying is slower than expected from kinetic studies. The deviation is explained from the difference in the physical state of the samples used in the drying experiments, i.e. original plant tissue versus the grounded state of the plant tissue used in the experiments for the kinetic studies. The results indicate that besides temperature and moisture content the physical state is also an important aspect in the degradation of nutritional compounds and enzymes.     

A rapid quantitative determination of phenolic acids in Brassica oleracea by capillary zone electrophoresis

A simple and rapid capillary zone electrophoresis method to quantitatively determine the phenolic acid contents in brassica vegetables is described. Phenolic compounds were extracted from broccoli, broccolini, Brussels sprouts, cabbage and cauliflower and the main hydroxycinnamic acids (sinapic, ferulic, p-coumaric and caffeic acids) were isolated by solid phase extraction with C18 cartridges. Using an optimised method, the four analytes were separated in less than 7 min in a 50 μm × 60 cm capillary with a 15 mM borate buffer (pH = 9.13) and a separation voltage of 30 kV at 30 °C. A linear relationship was observed for the method (r = 0.9997–0.9999) with detection limits ranging from 1.1 to 2.3 mg/kg of vegetables for the analytes. This method demonstrated good reproducibility with coefficients of variation of less than 5% for peak area and less than 1% for migration time (n = 7). The method was successfully applied to quantitatively determine the phenolic acid contents in a range of brassica vegetables and the results were in good agreement when compared to those from high performance liquid chromatography analysis.     

The use of glucosinolates for cultivar identification in swede,Brassica napus L var napobmssica (L) peterm

A quantitative study of the glucosinolates in the seed, cortex and medulla (peeled root) from nine cultivars (cvs) of swede, Brassica napus L var napobrassica (L) Peterm using high performance liquid chromatography was undertaken to see whether such characteristics could be used as a biochemical index of cultivar identity. All nine cultivars could be distinguished following an analysis of medulla glucosinolates, but the analysis of seed and cortex glucosinolates yielded no such useful information.