The effect of cooking on Brassica vegetables

Assessing antioxidant intake requires a food antioxidant database. However, cooking may affect antioxidant content due to antioxidant release, destruction or creation of redox-active metabolites. Here, effects of boiling, steaming and microwaving of broccoli, cauliflower, cabbage and choy-sum (Chinese cabbage) were explored by measuring antioxidant contents of raw and cooked vegetables. Cooking water was also tested. For all cooked vegetables, antioxidant content was highest in steamed > boiled > microwaved, and decreased with longer cooking time, regardless of method. All steamed vegetables had higher antioxidant contents than had matching raw vegetables. Effects were variable for boiling and microwaving. Microwaving caused greater antioxidant loss into cooking water than did boiling. Marked losses of anitoxidants occurred in microwaved cabbage and spinach. To assess food antioxidant content/intake accurately, cooking effects need detailed study. Steaming may be the cooking method of choice to release/conserve antioxidants. The cooking water is a potentially rich source of dietary antioxidants.     

不同蒸制方式下太湖蟹感官评定及营养价值比较

对比明火蒸锅与电蒸箱两种蒸制工具对太湖蟹感官评定及营养价值的影响。通过失重率、水分和感官3个过程指标,确定电蒸箱和明火蒸锅蒸制太湖蟹的感官最佳时间;比较了两种蒸制方式的最佳条件下,太湖蟹蟹肉和蟹黄/膏的基本营养成分、维生素、氨基酸、脂肪酸和功能性成分。结果表明:两种蒸制方式下的太湖蟹的失重率随着蒸制时间的延长而上升,可食部的水分逐渐下降;电蒸箱和明火蒸锅蒸制的最佳感官时间分别为25,20min,在该条件下,电蒸箱蒸制蟹的基本营养成分和维生素含量均高于明火蒸锅蒸制;氨基酸总量、必需氨基酸和呈味氨基酸含量也优于明火蒸锅蒸制;电蒸箱蒸制蟹的单不饱和脂肪酸(MUFAs)所占比例显著高于明火蒸锅,且DHA(C_(22:6))和虾青素含量均为明火蒸锅的2倍以上。该研究对日常烹调和企业生产都具有一定的指导意义。     

Effect of Domestic Cooking Methods on Antioxidant Capacity of Fresh and Frozen Kale

The aim of this study was to evaluate the changes in the antioxidant capacity of fresh and frozen kale during domestic cooking methods (e.g., boiling, microwaving, and steaming). The antioxidant activities of the samples were measured using three in vitro assays (1,1-diphenyl-2-picrylhydrazyl assay, 2, 2’-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid assay, and ferric reducing antioxidant power assay). The steaming treatment was found to be the best cooking method to retain antioxidant compounds, followed by the microwaving and boiling treatments. The frozen uncooked samples exhibited a higher antioxidant capacity than the fresh, uncooked samples, indicating that the freezing process could enhance the antioxidant capacity of the kale.     

烹调方式及4℃模拟配送中青椒营养品质及亚硝酸盐含量变化

本实验通过测定同一烹调成熟度下我国主要烹调方式及模拟餐饮冷藏配送过程中青椒营养品质和亚硝酸盐含量的变化,确定青椒最佳冷藏配送时间以及准确评估我国居民营养素的摄入量。以青椒为原料,以硬度作为烹调成熟度的统一标准,以传统烹调方式炒制、蒸制、煮制、微波为烹调方法,研究青椒在烹调后及模拟4℃冷藏配送0、1、4、8、12、24 h复热青椒的营养品质及亚硝酸含量变化。结果表明:烹调使VC含量显著降低,烹调后其真实保存率为76.3%~84.0%;总酚含量和抗氧化活性烹调后显著增加,总酚含量的真实保存率、1,1-二苯基-2-三硝基苯肼自由基清除能力的真实保存率、铁离子还原能力的真实保存率分别为97.7%~130.6%、156.76%~203.79%、156.94%~172.53%;除煮制使青椒可溶性固形物含量显著降低22.06%,其他几种烹调方式可以很好地保存可溶性固形物。烹调还会使亚硝酸盐含量显著降低6%~18%,更利于人体健康。在统一烹调标准下,不同烹调方式对VC含量影响无显著差异,炒制较其他几种方式相比能更多地增加总酚含量,蒸制和煮制能更多地增加抗氧化活性,煮制可以更多地减少亚硝酸盐的含量。综合而言,蒸制处理的青椒能更好地保持青椒的营养品质,且显著降低亚硝酸盐含量,更利于人体健康,建议对青椒的食用以蒸制处理后食用为好。在24 h模拟配送过程中,烹调青椒的营养品质呈下降趋势,亚硝酸盐含量呈缓慢上升趋势;蒸制和微波处理的青椒品质变化相对缓慢,更适宜作为模拟冷配送的前处理过程;营养物质在前8 h内快速下降,亚硝酸盐含量在模拟配送24 h显著增加,建议以青椒为原料的餐饮冷藏配送时间不宜超过24 h,且应在前8 h内采取保护措施。     

The antioxidant capacity and polyphenol content of organic and conventional retail vegetables after domestic cooking

Vegetable consumption is associated with health benefits. Organic foods are thought to have higher contents of antioxidant substances. The objective of this work is to quantify soluble and hydrolyzable polyphenols, ascorbic acid, and the antioxidant capacity of fresh conventional and organic retail vegetables (potato, carrot, onion, broccoli, and white cabbage) while evaluating the effect of boiling, microwaving, and steaming on these parameters. The recovery rate for soluble and hydrolyzable polyphenols was variable according to the vegetable analyzed. However, soluble polyphenols resulted in lower recovery rates than did hydrolyzable phenolics after cooking. Organic vegetables showed higher sensitivity to heat processing than did conventionally grown vegetables. In general, cooking was found to lead to reductions in the antioxidant capacity for most vegetables, with small differences between the cooking methods applied. Even with the alterations in their content, polyphenols showed a positive correlation with antioxidant capacity in raw and cooked vegetables from both types of agriculture.     

不同烹调方式对蔬菜植物化学物及V_C的影响

目的:研究不同家庭烹调方法对紫薯、西兰花和青辣椒中的花色苷、硫苷、辣椒素和V C的影响。方法:三种蔬菜经过微波、蒸制、焯制和油炒等烹调后,以pH示差法测定花色苷,以高效液相色谱法测定硫苷和辣椒素,以2,6-二氯靛酚滴定法测定V C。结果:保存V C效果:蒸制>微波蒸制,焯制>油炒>微波煮制;保存花色苷效果:蒸制>微波蒸制,且蒸制使花色苷增加;保存总硫苷效果:油炒>焯制>微波煮制;保存辣椒素效果:微波煮制>焯制>油炒。结论:若控制烹调时间不过长,蒸制是最适宜保存蔬菜植物化学物及维生素的烹调方法。      

基于主成分分析法的熟化马铃薯品质评价

以‘紫花白’马铃薯为原料,研究汽蒸、水煮、微波、烘烤、Air-frying（无油）、Air-frying（加油）、油炸7 种熟化方式对其基本营养成分和核苷酸类鲜味物质、质构、色泽及感官品质的影响,并对其品质指标进行主成分分析。结果表明：汽蒸和微波可最大程度地降低马铃薯基本营养成分的损失;微波显著提升了马铃薯核苷酸类鲜味物质含量且含量最高;Air-frying（无油）显著影响马铃薯质构特性;Air-frying（加油）与油炸显著加深马铃薯色泽;水煮熟化后马铃薯感官评分最高;经主成分分析后,7 种熟化方式下马铃薯品质评价综合得分由大至小依次是：Air-frying（加油）＞微波＞油炸＞水煮＞烘烤＞汽蒸＞Air-frying（无油）。由此得出结论：汽蒸可作为马铃薯深加工前期熟化处理的较优选择;Air-frying（加油）可较好地保留其品质特性,微波可满足摄食低脂类食品消费者的需求。     

The influence of processing and preservation on the retention of health-promoting compounds in broccoli

ABSTRACT:  In this work the effects of common household practices such as chilling, freezing, and cooking on vitamin C retention in broccoli (Marathon cv.), as well as their influence on the release of sulforaphane upon enzymatic hydrolysis of glucoraphanin by the endogenous enzyme myrosinase, were investigated. When chilled at 6 °C and 95% R.H. for 35 d, broccoli showed a vitamin C and sulforaphane loss of about 39% and 29%, respectively, while storage at –18 °C for 60 d resulted in similar losses, but mainly due to the blanching step. Boiling, steaming, microwaving, pressure-cooking, and the combined use of pressure and microwaves were the cooking methods investigated. Boiling and steaming caused significant vitamin C losses, 34% and 22%, respectively, while with the other treatments more than 90% retention was observed. Sulforaphane was no more detectable after boiling or steaming, while pressure/microwave cooking did not cause any significant loss. The quantitative distribution of these moieties in the florets and stems of fresh and chilled broccoli was also investigated.     

烹饪方式对蔬菜营养、抗氧化能力及色泽影响的研究进展

烹饪是对食材加工处理,使食物更可口、更好看、更好闻的处理方式,不仅让人在食用时感到满足,而且能让食物的营养更容易被人体吸收。蔬菜作为一类常见食用食材,不论是在家庭还是餐馆,都是必不可少的。烹饪过程会对蔬菜进行加热,从而改变了蔬菜的营养成分和色泽。相比于其他烹饪方式,蒸制可能是一种最为健康的烹饪方式,可以保留较多的营养物质。本文对蒸、煮、微波、炒制等几种常用的家庭烹饪方式对于蔬菜中多种营养物质和抗氧化能力的影响,以及对色泽的影响进行了概述,以期为消费者选择合适的烹饪方法提供参考。     

Influence of Different Cooking Methods on the Concentration of Glucosinolates and Vitamin C in Broccoli

Broccoli belongs to the Brassicaceae family and the Brassica genus, also designated crucifers, which has been linked to reduced risk of certain diseases for their content of compounds like glucosinolates (GLS) and vitamin C. Isothiocyanates, nitriles, and thiocyanates are degradation products of glucosinolates, are substances that protect cells against oxidative stress, and present many other health benefits. Vitamin C also contains antioxidant properties that contribute to the beneficial effects that broccoli have for health. The present paper is an overview of the reduction of secondary plant products, such as GLS and vitamin C, by cooking. Nonetheless, these concentrations can be modified if the cell structure of the plant is disrupted, e.g., while cutting, chewing, or cooking. Myrosinase can come into contact with GLS and hydrolyze it to isothiocyanate sulforaphane or sulforaphane nitrile, depending on the environmental conditions, which produces changes in the composition and concentration of GLS. Thus, cooking induces many chemical and physical modifications in food, among which GLS and vitamin C content in broccoli can change. Vitamin C and GLS are water-soluble, which makes them more susceptible to loss during the cooking process. Despite some controversy, most reviewed studies show that conventional cooking methods (boiling, steaming, and frying) and nonconventional ones (microwaving) significantly lead to the degradation of vitamin C and GLS. Nonetheless, steaming is the conventional method that obtains the best result to better preserve these two compounds.     

Effect of different cooking methods on the content of vitamins and true retention in selected vegetables

This study evaluated the effect of different cooking methods including blanching, boiling, microwaving and steaming on the content of vitamins in vegetables. True retention was estimated using the yield expressed as a ratio of the weight of the cooked sample to the weight of the raw sample. The retention of vitamin C ranged from 0.0 to 91.1% for all cooked samples. Generally, higher retention of vitamin C was observed after microwaving with the lowest retention recorded after boiling. Cooked vegetables were occasionally higher contents of fat-soluble vitamins, including α-tocopherol and β-carotene, than that of their fresh counterparts, but it depends on the type of vegetables. Microwave cooking caused the greatest loss of vitamin K in crown daisy and mallow; in contrast, it caused the least loss of vitamin K in spinach and chard. Cooking may cause changes to the contents of vitamins, but it depends on vegetables and cooking processes.     

Effect of Different Cooking Methods on Minerals,Vitamins, and Nutritional Quality Indices of Rainbow Trout (Oncorhynchus mykiss)

In this study, the influence of four cooking methods (baking, boiling, microwaving, and frying) on the nutritional value of rainbow trout was determined. Proximate, fatty acid composition, vitamin, mineral contents, and nutritional quality indices of rainbow trout were investigated (i.e., before and after cooking treatments). In all samples, there was reduction of total n-3 than raw fish fillets. Considering overall nutritional quality indices, vitamin, and mineral contents; baking and boiling were the best cooking methods among other methods used in this study.     

Cooking method significantly effects glucosinolate content and sulforaphane production in broccoli florets

It is known that glucosinolate levels in Brassica vegetables can be affected during cooking but little is documented about the effect of cooking on isothiocyanate production. In this study, three cooking methods were evaluated for their effects on the contents in broccoli florets of the glucosinolates, glucoraphanin (GR), glucobrassicin (GB), neoglucobrassicin and progoitrin, as well as on sulforaphane (SF) and sulforaphane nitrile (SFN) production in broccoli florets. Two broccoli cultivars, ‘Marathon’ and ‘Booster™’, were analysed raw and after they were steamed, microwaved (with water) or boiled for 2 or 5 min. Residual cooking water from all treatments was collected and analysed for GR and GB to determine the extent of leaching of intact glucosinolates. Irrespective of time, steaming resulted in significantly greater retention of GR, GB and SF, while boiling and microwave cooking resulted in significant losses of GR, GB and SF in both varieties. Glucosinolate content in the residual cooking water was highest after boiling and microwaving. Loss of SF production was primarily due to both leaching of GR into cooking water and thermal inhibition of ESP and myrosinase once internal floret temperatures exceeded 70 °C. Cooking method can significantly alter content of potentially beneficial compounds in broccoli florets and optimal SF ingestion may be obtained by eating raw or lightly steamed broccoli florets.     

不同烹饪方式对西兰花中维生素C和硝酸盐含量及体外模拟胃肠消化的影响

为了探究易于西兰花消化吸收健康烹饪方式,采用体外模拟胃肠消化技术,探究了6种不同烹饪方式（蒸烤微一体机蒸制、烤制、微波、组合模式、电磁灶蒸制和电磁灶煮制）对西兰花中维生素C和硝酸盐保留率及吸收率的影响。结果表明,达到相同成熟度时,电磁灶煮制时间（1~3 min）最短,烤制时间（6~11 min）最长。另外,微波模式和蒸制（一体机蒸制和电磁灶蒸制）模式在维生素C的保留及消化方面较优,而烤制、组合模式及电磁灶蒸制的样品硝酸盐保留率及吸收率最好。因此,电磁灶蒸制模式（中高档蒸制）是最易于人体维生素C和硝酸盐消化吸收的西兰花烹饪方式。     

Induced changes in bioactive compounds of kailan-hybrid broccoli after innovative processing and storage

The glucosinolates, sulforaphane, vitamin C and lutein content after several industrial cooking methods on the new kailan-hybrid broccoli and their changes during storage for 45 days at 4 °C were studied. Boiling and sous vide induced the highest glucosinolate loss (80%), while low pressure (LP) steaming, microwaving (MW) and sous vide-MW showed the lowest (40%) loss. Glucoraphanin was the most thermostable glucosinolate. Throughout their commercial life, microwaved and grilled samples showed a decrease in total glucosinolates. Generally, myrosinase activity was completely inhibited after cooking with undetected sulforaphane contents. The initial total vitamin C dropped by up to 58% after cooking and progressively decreased during storage, with sous vide-MW (92%) and microwaving (21%) showing the highest and lowest decrements, respectively. LP steaming and microwaving were the best industrial cooking methods for maintaining the glucosinolate and vitamin C contents, and enhancing up to 7.5-fold the initial lutein content.     

不同烹饪方式对淮山结构和糊化性质的影响

本实验采用水煮、清蒸、热炒和微波4 种烹饪方式对淮山进行加工,通过对烹饪后的淮山进行质构分析、扫描电子显微镜观察以及傅里叶变换红外光谱、X射线衍射和糊化性质分析,研究烹饪方式对淮山质构、结构和糊化性质的影响。结果表明,经不同烹饪方式处理后,淮山样品硬度均显著降低（P＜0.05）;经微波烹饪处理后,淮山样品咀嚼性显著升高（P＜0.05）,而经清蒸和水煮烹饪处理的淮山样品咀嚼性显著降低（P＜0.05）。烹饪处理的淮山样品中淀粉呈现不同程度的糊化,晶体结构均出现不同程度破坏,微波烹饪处理的淮山中淀粉糊化程度最低,清蒸样品中淀粉颗粒分子有序程度和结晶度最低。不同烹饪方式对淮山糊化性质的影响差异明显,微波烹饪处理后糊化温度显著升高（P＜0.05）,而其他烹饪方式处理后糊化温度显著降低（P＜0.05）。综上,不同烹饪处理对淮山的结构和糊化性质影响不同,研究可为淮山科学烹饪提供理论依据。     

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.     

Phenolic compound contents in edible parts of broccoli inflorescences after domestic cooking

Total flavonoid and individual hydroxycinnamoyl derivative (sinapic and caffeoyl‐quinic acid derivative) contents were evaluated in the edible portions of freshly harvested broccoli (cv Marathon inflorescences) before and after cooking and in the cooking water. High‐pressure boiling, low‐pressure boiling (conventional), steaming and microwaving were the four domestic cooking processes used in this work. The predominant sinapic acid derivatives were identified as 1,2,2′‐trisinapoylgentiobiose and 1,2′‐disinapoyl‐2‐feruloylgentiobiose. In addition 1,2‐diferuloylgentiobiose and 1‐sinapoyl‐2,2′‐diferuloylgentiobiose were also identified in broccoli inflorescences. The results showed large differences among the four treatments in their influence on flavonoid and hydroxycinnamoyl derivative contents in broccoli. Clear disadvantages were detected when broccoli was microwaved, namely high losses of flavonoids (97%), sinapic acid derivatives (74%) and caffeoyl‐quinic acid derivatives (87%). Conventional boiling led to a significant loss of flavonoids (66%) from fresh raw broccoli, while high‐pressure boiling caused considerable leaching (47%) of caffeoyl‐quinic acid derivatives into the cooking water. On the other hand, steaming had minimal effects, in terms of loss, on both flavonoid and hydroxycinnamoyl derivative contents. Therefore we can conclude that a greater quantity of phenolic compounds will be provided by consumption of steamed broccoli as compared with broccoli prepared by other cooking processes. Copyright © 2003 Society of Chemical Industry     

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.     

烹饪过程对空心菜和卷心菜硝酸盐潜在安全风险的影响

研究4种烹饪（油炒、汽蒸、微波和水煮）过程对空心菜和卷心菜中硝酸盐、亚硝酸盐和抗氧化能力的影响,并通过抗氧化性/体内亚硝酸盐比（antioxidant/in vivo nitrite ratio,A/N）值评价其硝酸盐潜在安全风险。结果表明,油炒会同时提升叶类蔬菜的硝酸盐含量（28.03%～49.57%）和铁离子还原能力（108.88%～218.35%）,而水煮则相反。微波和汽蒸在降低蔬菜硝酸盐含量（31.25%～46.61%）的同时提升铁离子还原能力（76.35%～112.99%）。基于可食用性和A/N值评价结果,在烹饪2 min内空心菜和卷心菜分别选择水煮和油炒烹饪对硝酸盐潜在安全风险的控制效果更好。微波是两种叶类蔬菜相对安全的烹饪方式,但不宜超过4 min,而汽蒸更适宜长时间烹饪（>4 min）。