SENSORY, NUTRIENT AND CHLOROPHYLL CHANGES IN BROCCOLI FLORETS DURING CONTROLLED ATMOSPHERE STORAGE

Sensory (color, turgor, decay) and nutritional (vitamin C, β-carotene) quality of broccoli florets were evaluated during storage at 4C in air or under a controlled atmosphere containing 2% O₂+ 6% CO₂ (CA). Shelf-life, green color and chlorophyll retention were greater under CA than in air, although loss of stem turgor was accelerated. All samples stored in air had decayed sufficiently by the fourth week to be unfit for consumption, while samples stored under CA showed a few spots of decay after five weeks. However, CA was associated with browning at the cut surface of the stem. Retention of vitamin C was slightly greater in CA than in air, while β-carotene content increased at the end of CA storage. Returning the samples to ambient conditions for 24 h after storage under either conditions resulted in chlorophyll and vitamin C losses, whereas β-carotene content remained stable.     

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.     

采后青花菜花球抗氧化水平变化与衰老的关系

为研究采后青花菜花球抗氧化水平变化与衰老的关系,将采后青花菜花球贮藏于20℃条件下,连续4 d测定了花蕾衰老生理指标(叶绿素、蛋白质、丙二醛(MDA)含量)及抗氧化水平指标(抗坏血酸(AsA)和β-胡萝卜素(β-Car)含量、超氧化物岐化酶(SOD)、过氧化氢酶(CAT)、过氧化物酶(POD)和抗坏血酸过氧化氢酶(APX)活性)。结果表明:贮藏过程中,叶绿素和蛋白质含量逐渐减少,MDA含量逐渐增多;AsA和β-Car含量逐渐减少,SOD、CAT和POD活性逐渐升高,APX活性逐渐降低;这些抗氧化水平指标与衰老生理指标的线性相关性均在1%水平显著。说明采后青花菜花球的抗氧化水平变化与衰老密切相关。     

Changes in post-harvest phytochemical qualities of broccoli florets during ambient and refrigerated storage

The effect of ambient and refrigerated storage temperature on post-harvest phytochemical qualities of broccoli florets was investigated during storage. Fresh broccoli florets were packed in polypropylene (PP) micro-perforated film bags and stored, under open ambient storage conditions (15 ± 1 °C, 55 ± 2% RH), and laboratory refrigerated storage (4 ± 0.5 °C, 50 ± 2% RH) for a total period of 144 h. Quality of broccoli florets was evaluated in terms of physiological weight loss (PLW), ascorbic acid content, chlorophyll content, β-carotene and total antioxidant activity. Samples packed in PP micro-perforated film showed significantly (P < 0.05) lower losses of PLW, ascorbic acid, chlorophyll, β-carotene and total antioxidant activity (5.51%, 4.53%, 18.9%, 4.04% and 16.4%, respectively), during storage for up to 144 h under refrigerated conditions. For better phytochemical retention, the broccoli florets should be packed in PP micro-perforated film bags and stored under refrigerated conditions.     

NUTRIENT QUALITY OF SELECTED VEGETABLES PREPARED BY CONVENTIONAL AND COOK-FREEZE METHODS

Selected vegetables (spinach, broccoli, sweet potatoes, and collard greens) prepared in 2.27 kg (5 lb) quantities by boiling, were frozen and stored for six months at ?18°C. Zinc, iron, β-carotene, and ascorbic acid were determined on the raw vegetable immediately after cooking and after reheating in a microwave oven subsequent to 6 months frozen storage. The greatest nutrient loss occurred for water soluble nutrients during boiling. Nutrient comparison between cooked samples (conventional method) and samples microwaved after 6 months frozen storage (cook-freeze method) indicated that differences existed only in ascorbic acid content of spinach. Data indicated that vegetables prepared by cook-freeze, a method used by health care institutions, were generally equal in nutrient quality to conventionally prepared vegetables.     

VITAMIN C AND β-CAROTENE IN FRESH AND FROZEN GREEN BEANS AND BROCCOLI IN A SIMULATED SYSTEM

The reduced ascorbic acid and β-carotene contents of “retail market-fresh” (RMF) and “fresh-frozen” (FF) green beans and broccoli in a simulated handling system were determined. Changes in ascorbic acid content in the two vegetables during a retail market period and frozen storage followed different patterns. In green beans, ascorbic acid content decreased during refrigerated storage for up to 7 days, but in broccoli there was a significant increase. Blanching resulted in a loss of approximately 40% of the ascorbic acid in broccoli. Ascorbic acid content of FF green beans stored at-20C for 16 weeks was approximately twice that in RMF green beans, but in FF broccoli stored under the same conditions it was only about half that of RMF broccoli. β-carotene content of green beans and broccoli did not change during either the retail market simulation of frozen storage and did not differ from that of fresh.     

Influence of postharvest UV‐C treatment on refrigerated storage of minimally processed broccoli (Brassica oleracea var. Italica)

Minimally processed broccoli was treated with UV‐C light (8 kJ m^?2) and subsequently stored for 21 days at 4 °C. The UV‐C treatment delayed yellowing and chlorophyll degradation during storage. Treated broccoli florets displayed lower electrolyte leakage and respiratory activity, indicating higher tissue integrity. Treated samples showed higher phenolic and ascorbic acid contents as well as higher antioxidant activity than controls. Treated samples also had a higher content of soluble sugars, but no differences in the content of soluble proteins between control and treated samples were detected. The UV‐C treatment also affected bacterial and mould populations. After 21 days at 4 °C the number of colony‐forming units of both populations was lower in treated than in control broccoli florets. The results suggest that UV‐C treatment reduces tissue damage of minimally processed broccoli during storage at 4 °C, thus maintaining nutritional quality and reducing microbial growth. Copyright © 2007 Society of Chemical Industry     

Physiology and Quality Responses of Fresh-cut Broccoli Florets Pretreated with Ethanol Vapor

ABSTRACT:  The exposure of intact broccoli to 6 mL/kg ethanol for 5 h was effective in inhibiting the senescence of fresh-cut broccoli florets. During the 8 d of storage at 10 °C, the weight loss, protein, and chlorophyll degradation of the treated broccoli florets were significantly retarded. The ethanol content of the ethanol-treated broccoli rose sharply and then descended rapidly to a level close to that of the control broccoli stored at 10 °C after 8 d. The acetaldehyde level of the treated broccoli was higher than that of the control broccoli over the whole storage period. The alcohol dehydrogenase activity of the treated broccoli was significantly higher than that of the control after 6 d. There had been higher activities of peroxidase, superoxide dismutase, and catalase in ethanol-treated broccoli. Our study showed that the fresh-cut broccoli treated with ethanol maintained better quality during the storage. Ethanol vapor would be commercially a good candidate for extending the shelf-life of fresh-cut broccoli florets and reducing the loss in postharvest.     

Effects of processing and packaging on vitamin C and β-carotene content of ready-to-use (RTU) vegetables

High pressure liquid chromatographic methods were used for measurement of the concentration of vitamin C and β-carotene in broccoli and green pepper. The effects of processing, packaging and storage on the levels of these nutrients in both unprocessed and processed ready-to-use (RTU) vegetables were determined. Systems investigated included: (a) unpacked and pillow packaged broccoli, and (b) unpacked, pillow, partial vacuum, and total vacuum packaged green pepper. There was a statistically significant decrease in vitamin C over a 10 day storage period of unpacked and packaged vegetables including all four packaging systems (P<0.001, overall average decrease of 11%). The overall loss of β-carotene during the 10 day storage period was not statistically significant (P=0.14). Although there was a significant loss in vitamin C during storage, in most cases there was no difference in loss of vitamin C or β-carotene between the processed and unprocessed vegetables, and the packaging systems.     

Effect of freezing and storage on quality factors in Hamburg and leafy parsley

Two types of parsley — the Hamburg cv Berli ska and leafy type cv Paramount — were frozen and stored at temperatures of −20 and −30 °C for 9 months. One half of the material was blanched before freezing and the other half was non-blanched. In 100 g fresh leaves of Hamburg parsley there were 20.0 g of dry matter, 310mg of vitamin C, 7.5mg of β-carotene, 203mg of chlorophyll, 30.8 mg N---NO₃ and 0.078 mg N---NO₂. For the leafy type the corresponding values were 17.3 g, 257 mg, 9.4mg, 68.5mg, and 0.077mg. The material blanched before freezing showed significant losses in the contents of vitamin C (47–51%), nitrates (22–33%), and nitrites (43–55%) and distinctly smaller ones but also significant in the case of dry matter. During freezing and storage of frozen products there were losses in vitamin C, β-carotene, and chlorophyll while the levels of nitrates and nitrites were variable. Particularly great losses of vitamin C and β-carotene were observed in the non-blanched frozen leaves stored at −20 °C. After 9 months' storage, frozen products preserved 10–44% of vitamin C, 37–91% of β-carotene, 78–95% of chlorophyll, and 78–153% of nitrates. Of the types of parsley analyzed the Hamburg type was a better raw material for freezing because of a significantly higher content of vitamin C and chlorophyll and significantly less nitrates in frozen products. When the storage temperature was −30 °C, the blanching of leaves was not necessary, although it helped their pressing into cubes.     

Effect of hot air treatments on senescence and quality parameters of harvested broccoli (Brassica oleracea L var Italica) heads

Treatments with hot air were applied to broccoli (Brassica oleracea L) florets to investigate the effect on several quality and senescence parameters. To select the optimum treatment, florets were treated with different combinations of time/temperature ranging from 1 to 3 h and 37 to 50 °C and then placed in darkness at 20 °C. Most treatments delayed yellowing and loss of chlorophylls, except those performed at 37 °C, which accelerated senescence. Treatment at 48 °C for 3 h caused the highest delay in chlorophyll loss and was chosen to analyse its effect on quality and senescence. Non‐treated florets showed yellowing and reduced their chlorophyll content during storage. Heat treatment delayed the onset of chlorophyll catabolism by 1 day and slowed down the rate of degradation. Treated florets also showed lower losses of total sugars and proteins and an inhibition of protein solubilisation. Control heads showed an increment in CO₂ production, which was not detected in heat‐treated florets. Total antioxidants decreased and thiobarbituric acid‐reactive substances (TBARS) increased during storage. The treatment delayed the decrease in antioxidant content and inhibited the increment in TBARS. In conclusion, treatment at 48 °C for 3 h delayed broccoli senescence at 20 °C and contributed to maintaining an overall better quality of the product. Copyright © 2005 Society of Chemical Industry     

微酸性电解水对采后西兰花贮藏品质的影响

为了探究微酸性电解水（Slightly acidic electrolyzed water,SAEW）对采后西兰花贮藏品质的影响,本研究首先进行了微酸性电解水浓度的筛选,将西兰花切成均等的小花球,随机分成五组,以自来水浸泡15 min后晾干作为对照,以25、50、75和85 mg/L的微酸性电解水浸泡15 min后晾干作为不同处理组,置于15±1 ℃贮藏4 d,依据不同浓度微酸性电解水对采后西兰花外观品质、总叶绿素及丙二醛（MDA）含量的影响筛选最适宜的浓度。结果表明,与对照和其它浓度的SAEW处理相比,50 mg/L SAEW可更好地维持采后西兰花的外观品质及总叶绿素含量,并抑制其MDA含量的积累。进一步研究显示,与对照组相比,50 mg/L SAEW可有效维持采后西兰花的感官品质,抑制其菌落总数的升高,延缓其维生素C、可溶性糖、可溶性蛋白、可滴定酸、总硫苷和萝卜硫素含量的下降,并可有效抑制组织中亚硝酸盐含量的升高。这些结果表明50 mg/L SAEW可作为一种维持采后西兰花贮藏品质、延缓其衰老进程的有效处理方法。     

不同单色LED对低温贮藏西兰花的保鲜作用

为改善西兰花的采后贮藏品质,以期为蔬菜保鲜的实际应用提供新思路。本文研究了低温下不同波长的单色发光二极管(lighting-emitting diode,LED)对西兰花品质的保鲜作用。本研究采用了红光(642 nm)、黄光(591 nm)、绿光(519 nm)、蓝光(464nm)、紫光(435nm)不同波长的单色LED照射西兰花,光照时间24h/d,并从感官、理化、营养和微生物指标综合评价分析不同单色LED对西兰花不同贮藏时期品质的影响。结果表明:不同单色LED光照能延缓西兰花在贮藏过程中营养品质的下降。贮藏12 d后,绿光LED(519 nm)能够最大程度地保持西兰花的感官品质,抑制亮度L*的增加,延缓叶绿素、还原糖及可溶性固形物的降解,同时能够有效地抑制微生物的增长速度,延缓色相角度H值的降低、保持维生素C的含量。因此,绿光LED照射对于西兰花的低温贮藏品质的保持效果最佳,从而延长西兰花的贮藏期。     

Effects of traditional and modified technology,in the production of frozen cauliflower,on the contents of selected antioxidative compounds

The investigation concerned white and green cauliflowers: a traditional technology of freeze – blanched cauliflower, a modified technology of freeze – cooked cauliflower, and two temperatures of frozen storage at −20 and −30 °C for 0, 4, 8, and 12 months. Compared with the white cauliflower, the green variety was characterized by significantly greater contents of dry matter, vitamin C, carotenoids, β-carotene, polyphenols and a higher antioxidative activity at all the stages of evaluation. Depending on the investigated sample, after 12 months of refrigerated storage, cauliflower prepared for consumption retained 29–50% of vitamin C, 73–100% of carotenoids, 53–125% of β-carotene, 69–85% of polyphenols and 26–40% of antioxidative activity in comparison with the raw material. After a 12-month storage, the product obtained using the modified technology contained significantly more vitamin C and in general showed a higher antioxidative activity than did with the traditional product. The lower storage temperature resulted in significantly better retention of vitamin C and also – in some samples – a better retention of carotenoids, β-carotene, and polyphenols. A higher sensory quality was found in products of green cauliflower obtained according to the traditional technology.     

Antioxidant ability of broccoli flower buds during short-term storage

Some metabolic changes in broccoli heads stored under commonly-applied conditions were investigated. Freshly harvested broccoli of Lord cultivar were stored at 20°C and at 5°C for 3 and 7 days, respectively, either non-packaged or packaged in polymeric film samples. Short-term storage at room temperature induced accumulation of total phenols, especially in non-packaged broccoli. With low-temperature treatment, phenol content rose only after 7 day storage of non-packaged heads. Both low temperature and application of polymeric foil stopped losses of ascorbic acid. Total antioxidant activity increased considerably during storage in all treatments. Changes of fatty acids were manifested as a slight decrease in saturated fatty acids in cold storage and increase of polyunsaturated fatty acids in most treatments. Metabolism of fatty acids did not correspond to thiobarbituric acid-reactive substances (products of lipid peroxidation).     

EFFECT OF BLANCHING AND SULFITE TREATMENT ON THE QUALITY OF FROZEN CAULIFLOWER

The influence of blanching time and post-blanching sulfite treatment on the sensory quality and texture of frozen cauliflower were assessed after storage at -18°C for up to one year. The treated cauliflower florets, sealed in polyethylene bags, were placed in waxed paperboard cartons and frozen in a contact plate freezer at -35°C. Samples blanched for 3 min and dipped in a solution containing 1000ppm of SO₂ for 5 min gave a significantly (p<0.05) superior product even when stored for one year. The residual SO₂ content of 50 ppm found in these stored samples disappeared after a 3 min cooking in boiling water. Cauliflower texture was influenced by blanching time but the textural differences of blanched samples diminished following freezing and storage. After a 3 min cooking, the texture of all thawed samples were comparable to that of fresh cauliflower cooked for 10–12 min.     

Quality of broccoli as influenced by film wrapping during shipment

'Shogun' broccoli florets were film-wrapped and stored for 7 days at 1 °C to simulate a maximum period of commercial shipment. After cold storage, florets were kept for 2.5 days at 20 °C to simulate a retail sale period. For wrapping, polyvinyl chloride (PVC) 9 µm thickness and low-density polyethylene (LDPE) 11, 15, and 20 µm thickness were used. Soluble solids content, pH, titratable acidity, weight loss, physiological disorders, visual quality, and gas composition within packages were monitored. Gas composition (about 18% O₂ and 1% CO₂ during cold storage and about 16% O₂ and 2-3% CO₂ during shelf life), overall quality, and yellowing and browning of the florets were at similar levels among the films studied. However, weight loss was about sixty times lower for all LDPE films than for PVC film. After shelf life the best results were obtained by using 15 µm LDPE. This polymeric film could be a good alternative to PVC for wrapping broccoli for commercial shipment purposes, particularly to those countries where use of PVC has been forbidden.     

Snap Bean Quality Changed Minimally When Stored in Low Density Polyolefin Film Package

Snap beans packed in low density polyolefin film and stored at 5°C and 10°C were removed at days 0, 4, 8, 12, and 16 for quality evaluation. Chlorophyll content of beans stored at 5°C was not influenced by storage period. Pods stored at 10°C showed significant increase in chlorophyll after 4 days storage followed by a decline as time of storage increased. Hue angle and tristimulus a* corresponded more closely to chlorophyll content and were better indicators of snap bean color than chroma and tristimulus L* and b*. Weight loss, seed percentage and ascorbic acid were higher in pods stored at 10°C than in those stored at 5°C. Storage temperature and period had no influence on texture or soluble solids content.