Comparison of glucosinolate levels in commercial broccoli and red cabbage from conventional and ecological farming

Broccoli heads and red cabbage of both conventional and ecological origin were purchased from the market at monthly intervals over a 1-year period. After freeze-drying of the samples the glucosinolates were extracted, enzymatically desulphated and analyzed by HPLC-UV. Glucoraphanin, glucobrassicin and neo-glucobrassicin turned out to be the predominant glucosinolates in broccoli. Red cabbage contained similar amounts of glucoraphanin and glucobrassicin but, in addition, appreciable amounts of glucoiberin, progoitrin, sinigrin, gluconapin and glucoerucin, while neo-glucobrassicin occurred at trace levels only. No significance was found comparing the contents of glucoraphanin in the two cultivation groups for either broccoli or red cabbage. Organic broccoli and red cabbage both contained significantly higher amounts of glucobrassicin than their conventionally grown counterparts. Conventional crops of red cabbage yielded significantly higher quantities of gluconapin than ecological crops. Broccoli imported from Spain and Italy during the winter months yielded levels of glucosinolates similar to those of the home-grown products available in summer and autumn.

Effects of N6-Benzyladenine and Storage Temperature on Shelf-Life and Quality of Raw and Cooked Broccoli (Brassica oleracea L. var. italica)

Fresh broccoli heads were dipped in solutions containing 20 ppm N⁶-benzyladenine (BA) with 0.1% Tween-20 or water with 0.1% Tween-20 for 30 sec then stored for 5 wk at 2° and 5°C. Broccoli heads receiving BA treatments maintained higher subjective quality ratings for color, turgidity, aroma, flavor, and texture throughout the 5-wk period. Gardner color measurements and total chlorophyll were significantly higher for samples treated with BA and stored at 2°C than for controls. Samples stored at 2°C had lower shear resistance than those kept at 5°C. The content of hot water insoluble materials (fiber) was much less in broccoli heads treated with BA than in untreated heads. Maintenance of good quality by BA treatment and 2°C storage was reflected in all parameters of sensory evaluations for cooked broccoli. Loss of color and reduction of quality were observed in raw and cooked broccoli during 4 wk of storage. Evaluations of quality parameters and color measurements were greatly influenced by the turgidity factor.     

EFFECT OF ATMOSPHERE ON BROCCOLI SENSORY ATTRIBUTES IN COMMERCIAL MAP AND MICROPERFORATED PACKAGES1

Broccoli was packaged using 2 microperforated (cross-micro, SM60®) and 3 modified atmosphere packages (MAP) (polyethylene MAP, broccoli MAP, lettuce MAP). Packaged broccoli was stored 9 days at 2C and an additional 1, 3, 4 and 6 days at 13C, for a total storage 10, 12, 13 and 15 days, respectively. Concentrations of CO₂ and O₂ were determined after 12 days. Sensory analyses were conducted after 10, 12, 13, and 15 days. Broccoli quality was evaluated for ten sensory attributes by eight trained judges. Analysis of variance and principal component analysis were used to determine the effect of packaging and storage time. Broccoli packaged in lettuce MAP was most anaerobic (3.9% CO₂, 1.2% O₂) and developed sauerkraut-like odors/flavors after 10 days of storage. The microperforated wraps did not alter the gas composition of the packages (16.3% O₂, 0.2% CO₂) and broccoli became yellow and limp after 15 days. In contrast, broccoli packaged in the polyethylene and broccoli MAP packages modified the CO₂ and O₂ concentrations and maintained the broccoli quality for the duration of the experiment (15 days).     

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.     

Different postharvest strategies to preserve broccoli quality during storage and shelf life: Controlled atmosphere and 1-MCP

Broccoli (Brassica oleracea var. italica) is a vegetable that requires the application of postharvest techniques to extend its marketability. Controlled atmosphere and 1-MCP treatments are most used to extend the shelf life of broccoli and reduce post-harvest deterioration. The aim of this study was to evaluate the visual, physicochemical and functional changes of broccoli head samples stored at 1–2 °C and 85–90% relative humidity (RH) in air (Control samples), under controlled atmospheres (10% O₂ and 5% CO₂) (CA samples) and treated with 1-MCP (0.6 μL/L). After storage all samples were maintained at 20 °C for 2 and 4 days, in order to assess their shelf life. The most suitable postharvest treatment to extend broccoli quality during storage and shelf life, in terms of maintaining the visual quality and reducing loss of health-promoting compounds, was achieved by storage under controlled atmosphere conditions. The use of 1-MCP reduced the loss of green colour and chlorophyll pigments, but only during cold storage not during shelf life at 20 °C.     

Glucose,fructose and sucrose content in broccoli,white cabbage and Portuguese cabbage grown in early and late seasons

Consumption of Portuguese cabbage and white cabbage is very high in Portugal, but diets including broccoli have been highly recommended owing to recognition of the health‐protective effects of secondary plant metabolites. Broccoli production is generally concentrated in the summer/winter season, but the demand for a fresh product throughout the year requires production in other seasons. Sugars might affect flavour and the acceptance of broccoli by consumers. This study reports the free fructose, glucose and sucrose content in primary and secondary inflorescences of 11 cultivars of broccoli, one white cabbage and four Portuguese cabbages grown in early (March–July) and late (August–January) seasons in the northern region of Portugal. On average the results show that the total free sugar content in the broccoli cultivars, except for cv Marathon, is significantly (P < 0.05) lower than in the other cabbages. Fructose was the major sugar in the three types of Brassica, representing between 48.8 and 56.9% of the total sugar content in broccoli cvs Marathon and Senshi respectively and between 48.7% (cv Mirandela) and 53.8% (cv Murciana) in the other cabbages. Glucose was the second major sugar, while sucrose represented a maximum of 20.5% in broccoli cv Shogun and 11.1% in cv Murciana. The growing season influenced the free sugar content, with generally higher levels in the spring/summer than in the summer/winter season in broccoli, while an opposite tendency was noted in the other Brassica species. In broccoli the sugar levels in the primary inflorescences were generally lower than in the secondary inflorescences, except for sucrose. © 2001 Society of Chemical Industry     

Influence of light on health‐promoting phytochemicals of broccoli sprouts

BACKGROUND: Broccoli (Brassicaceae) is a rich source of phytochemicals (glucosinolates and phenolic compounds) and micronutrients (vitamins and minerals). Germinated broccoli sprouts contain much higher levels (10–100 times) of aliphatic (glucoraphanin) and indolic glucosinolates than the inflorescences. This quality characteristic of broccoli sprouts plays an important role in human health and disease prevention. Although it is known that genetic and environmental factors can affect the composition of broccoli inflorescences, the influence of such factors on the seeds and sprouts has not been widely reported. Therefore the aim of this study was to determine the effect of light versus dark growth conditions on the phytochemical composition (vitamin C, phenolic compounds and glucosinolates) of broccoli sprouts. RESULTS: Broccoli sprouts grown in the light were found to have much higher concentrations of vitamin C (by 83%), glucosinolates (by 33%) and phenolic compounds (by 61%) than those grown in the dark. During a 7 day period there was a clear and analogous trend in both treatments, with a general reduction in concentrations over time. Among the different organs studied (seeds, cotyledons, stems and roots), the cotyledons contained the highest levels of bioactive compounds, while the roots contained the lowest. CONCLUSION: Light treatment of sprouting broccoli seeds increased their concentration of health‐promoting phytochemicals, mainly during the first 3–5 days of development. Therefore the younger broccoli sprouts are a better source of bioactive compounds for the consumer than the inflorescences. Copyright © 2008 Society of Chemical Industry     

The effects of cooking method on selected quality traits of broccoli and green asparagus

Broccoli and green asparagus were cooked using boiling water, steam, microwave oven and combi oven with overheated steam and combination of hot air with overheated steam (only broccoli). Vegetables were analysed for chlorophylls a and b, carotenoids, total polyphenols, antioxidant activity, colour parameters and sensory properties. Cooking in the combi oven with overheated steam was an effective method to achieve the highest levels of polyphenols and antioxidant activity, but it negatively influenced the contents of chlorophylls in both vegetables and carotenoids in asparagus. Boiling and cooking in the combi oven with overheated steam or hot air and steam ensured the best and comparable sensory properties of broccoli. Asparagus showed a lower susceptibility to heat treatments than broccoli as none of the treatments applied caused significant differences in colour redness and yellowness, polyphenol content and sensory properties of this vegetable.     

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.     

Retention of Phytochemicals in Fresh and Processed Broccoli

Our objective was to determine whether steam blanching, storage and preparation affected concentrations of sulforaphane (SF), sulforaphane nitrile (SFN), cyanohydroxybutene (CHB), iberin (I) or iberin nitrile (IN) in fresh and frozen broccoli. Broccoli (var. “Arcadia”) was grown in St. Charles, IL over three seasons. Samples were steam blanched (2 min at 93 ± 5°C) within 24h of harvest, frozen and stored at ?20°C up to 90 days, and fresh broccoli was stored at 4°C up to 21 days. Samples were analyzed uncooked or microwave cooked. SF, SFN, I, IN and CHB were determined by GC in dichloromethane extracts from lyophilized samples. Rates of loss for CHB and SF were similar during storage of fresh broccoli. Blanching, storage, and microwave cooking decreased (p < 0.01) concentrations of each compound in fresh and frozen broccoli.     

Effect of modified atmosphere packaging on visual quality and glucosinolates of broccoli florets

Broccoli (Brassica oleracea var. italica) florets were packaged in polyethylene bags with no holes (M₀), two microholes (M₁), and four macroholes (M₂), and then stored at 4 or 20 °C. The effects of modified atmosphere packaging (MAP) treatments on visual quality and glucosinolate contents were determined by comparing with non-wrapped florets. The results showed that MAP treatments, especially with M₀ and M₁, extended the shelf life and reduced the postharvest deterioration of broccoli florets stored at 4 and 20 °C. All three MAP treatments reduced the decreasing concentration rates of individual, total aliphatic and indole glucosinolates in broccoli florets when compared to those in the control, with M₀ being the most significant, followed by M₁ and M₂ during 23 days of storage at 4 °C or 5 days of storage at 20 °C. Broccoli florets with M₀ treatment maintained the visual quality and glucosinolate contents for 13 days at 4 °C and 3 days at 20 °C.     

SENSORY ATTRIBUTES AND NUTRIENT RETENTION IN SELECTED VEGETABLES PREPARED BY CONVENTIONAL AND MICROWAVE METHODS

Sensory characteristics and retention of vitamin C, vitamin B₆, calcium, and magnesium were determined in vegetables cooked by conventional and microwave methods. Fresh broccoli, cauliflower, and potatoes and frozen corn and peas were cooked by boiling, steaming, microwave boiling and microwave steaming to equivalent tenderness as measured by a shear press. The sensory analysis of the vegetables cooked by the four methods indicated that some differences existed in color, flavor, texture, and moistness of the vegetables. No one method resulted in vegetables with optimum sensory characteristics. The nutrient retention was highest in foods cooked by microwave steaming, followed by microwave boiling, followed by steaming, and then by boiling. Generally vegetables cooked by microwave techniques retained higher percentages of the U. S. Recommended Daily Allowances for the nutrients than those cooked by conventional methods.     

Electron-beam irradiation of fresh broccoli heads (Brassica oleracea L. italica)

Broccoli is a popular item in the diet of the US population, commonly found in salads ready-to-eat. The recent recalls of fresh produce due to contamination with Escherichia coli and other pathogens emphasize the need to find effective means to treat minimally processed fresh foods. Our study assessed the effect of ionizing radiation using electron beams on the shelf-life, physicochemical properties, and consumer acceptability of broccoli florets. One-hundred broccoli heads were irradiated at 1, 2, and 3 kGy with a 10 MeV linear accelerator at 22 °C. We monitored pH, color, texture, respiration rate, weight loss, chlorophyll, total carotenoids, and vitamin C of irradiated and non-irradiated samples at 5-day intervals up to 14 days at 4 °C and 95% RH. Fifty consumer panelists scored the samples using a nine-point hedonic scale.Irradiation did not affect color, firmness, pH, and weight loss of the samples. Both irradiated samples and controls showed a slight change in color during storage, though the effect was not dose-dependent. Irradiation affected (P < 0.05) the respiration rates on the first 5 days of storage (higher CO₂ levels) but all samples, including the controls, attained the same equilibrium value. Vitamin C content of all samples decreased (P < 0.05) with storage time. Chlorophyll and total carotenoids content followed the same trend. In terms of overall acceptability, color, odor, and texture, all irradiated samples were highly accepted by the panelists with scores of 5 and above. By the end of shelf-life, only the controls showed significant quality decline (yellow color, off-odor) due to microbial spoilage. In summary, electron-beam treatment up to 3 kGy maintains the overall quality of fresh broccoli.     

Impact of UV-B irradiation on chlorophyll degradation and chlorophyll-degrading enzyme activities in stored broccoli (Brassica oleracea L. Italica Group) florets

UV-B irradiation was applied to broccoli florets to investigate its effect on chlorophyll degradation and chlorophyll-degrading enzyme activities in stored broccoli. Broccoli florets were irradiated with UV-B doses at 4.4, 8.8, and 13.1 kJ m⁻² and then kept at 15 °C in darkness. We found that a UV-B dose of at least 8.8 kJ m⁻² efficiently delayed the decrease of the hue angle value and the contents of chlorophylls a and b. Chlorophyllide a and 13²-hydroxychlorohyll a gradually decreased with senescence. Pheophorbide a and pyropheophorbide a levels were significantly higher in broccoli without UV-B treatment. Chlorophyllase and chlorophyll-degrading peroxidase activities with UV-B treatment were suppressed, as well as the activity of Mg-dechelatase. Mg-dechelating substance activity was also suppressed with this treatment. We concluded that UV-B treatment effectively suppressed chlorophyll degradation in broccoli florets during storage, suggesting that the effect could be due to the suppression of chlorophyll-degrading enzyme activities.     

Effects of stir-fry cooking with different edible oils on the phytochemical composition of broccoli

ABSTRACT:  Numerous epidemiological studies indicate that Brassica vegetables in general and broccoli in particular protect humans against cancer; they are rich sources of glucosinolates and posses a high content on flavonoids, vitamins, and mineral nutrients. The contents of total intact glucosinolates, total phenolics, vitamin C, and minerals (potassium, sodium, calcium, magnesium, iron, manganese, zinc, and copper) in the edible portions of freshly harvested broccoli (florets), which was subjected to stir-frying treatments, were evaluated. In the present work, the stir-fry cooking experiments were carried out using different edible oils from plant origin (refined olive oil, extra virgin olive oil, sunflower oil, peanut oil, soyabean oil, and safflower oil) known and used worldwide. Results showed that during stir-frying, phenolics and vitamin C were more affected than glucosinolates and minerals. Stir-fry cooking with extra virgin olive, soybean, peanut, or safflower oil did not reduce the total glucosinolate content of the cooked broccoli compared with that of the uncooked sample. The vitamin C content of broccoli stir-fried with extra virgin olive or sunflower oil was similar to that of the uncooked sample, but greater than those samples stir-fried with other oils.     

不同质构特性西蓝花对口腔加工行为和米饭餐饱腹感的影响

为探究同样原料不同质构蔬菜对口腔加工行为、食物摄入和饱腹感的影响,以两种熟西蓝花为研究对象,分析健康受试者同时食用西蓝花与米饭或先食用西蓝花、后食用米饭时的口腔加工行为,并测定食物摄入量及餐后饱腹感相关指标。结果表明：与同时进食软西蓝花和米饭相比,先进食硬西蓝花、后进食米饭的处理可增加44%的咀嚼次数、34%的口腔感官暴露时间、57%的单位质量咀嚼次数,进食速率和米饭摄入量分别降低25%和20%,并有效抑制餐后饥饿感。结论：较硬西蓝花可通过促进口腔加工效应从而降低食物摄入并抑制餐后饥饿感,而这种效应在先进食西蓝花时表现得更为显著。     

Combined Post-harvest Treatments for Improving Quality and Extending Shelf-Life of Minimally Processed Broccoli Florets (<Emphasis Type="Italic">Brassica oleracea var. italica</Emphasis>)

Broccoli is an important source of many nutritional and bioactive compounds. However, its shelf-life is very short due to physicochemical losses and microbiological degradation. This study was undertaken to implement treatments that could improve the quality of ready-to-eat (RTE) broccoli during storage by evaluating the effect of pre-treatment with calcium chloride (CaCl₂) and alginate coating on the physicochemical and microbial properties of RTE broccoli. Broccoli florets were pre-treated with three different concentrations of CaCl₂ (1, 2.5, and 4 g L^?1), then coated with an alginate formulation (13 g L^?1) and stored at 4 °C for 24 days. Texture, color, weight loss, respiration rate, and total mesophilic flora (TMF) counts were evaluated at days 0, 3, 7, 14, and 24 of storage. The obtained results in this study showed that combining pre-treatment with calcium and alginate coating led to reducing the weight loss and respiration rate of broccoli, maintaining its color and texture as well as extending its shelf-life by 6 days. These results not only allowed reducing post-harvest losses resulting in the loss of the product but also have a major impact on the environment and resources involved in the production process.     

Influence of the season on the relationships between NMR transverse relaxation data and water‐holding capacity of turkey breast meat

In the last few years the poultry industry has seen a significant deterioration in meat quality properties during the summer season. The objective of this study was to evaluate the seasonal effect (summer and winter) on turkey meat quality assessed by both conventional and low‐resolution nuclear magnetic resonance (LR‐NMR) analysis. Eighty‐eight breast muscle samples (35 winter and 53 summer) from BUT‐Big 6 turkeys belonging to 16 different flocks, were randomly collected from a commercial processing plant. The samples were analysed for transverse relaxation times (T₂) by LR‐NMR and for initial pH (15 min post mortem), ultimate pH (24 h post mortem) and pH after cooking, temperature at 15 min post mortem, water‐holding capacity (WHC, drip loss, filter paper press wetness and cooking loss) at 24 h post mortem, colour of raw and cooked meat and chemical composition (moisture, lipids and proteins). The results indicate that, during the summer season, turkey breast meat undergoes a relevant WHC decrease. Cluster analysis of the raw LR‐NMR data evidenced the presence of two groups corresponding to samples harvested in each different season. Correlations between the LR‐NMR signal and the conventional parameters measuring WHC were obtained by a recently proposed type of principal component regression (PCR) termed relative standard deviation PCR. Copyright © 2004 Society of Chemical Industry     

Innovative Cooking Techniques for Improving the Overall Quality of a Kailan-Hybrid Broccoli

The microbial, physical, sensory and nutritional quality of boiled (vacuum and conventional), steamed, pressure cooked, sous vide, microwaved (sous vide and conventional), deep-fried (vacuum and conventional) and grilled kailan-hybrid broccoli (Bimi®) after cooking was studied. Sous vide microwaving greatly decreased microbial counts, achieving very low psychrophilic and enterobacteria counts (1.1 and 0.2 log CFU g^?1, respectively). Vacuum boiling and sous vide reduced the stem broccoli firmness by approximately 54–58 %, reaching a pleasant and moderate softening. Sous vide, grilling and steaming induced the lowest stem colour changes. Generally, all cooking treatments showed a good overall sensory quality. The total phenolic content (1,148 mg CAE kg^?1 fw) usually increased after cooking, with microwave and grilled treatments registering the highest increases up to 2-fold. Commonly, the total antioxidant capacity (296.6 mg AAE kg^?1 fw) increased after cooking by sous vide, microwaving and frying treatments registering the highest increments, by approximately 3.6-fold. Generally, the cooking process reduced the initial vitamin C content, with vacuum and conventional boiling showing the lowest and highest losses with 27 and 62 %, respectively, while vacuum deep frying preserved the initial value (1,737 mg kg^?1 fw). As a main conclusion, the studied grilling and vacuum-based cooking treatments resulted in better microbial quality, colour, stem firmness and sensory quality than the remaining ones. This maintained or even improved the total antioxidant content of the new kailan-hybrid broccoli studied.