The performance evaluation of a continuous vegetable cooker

Summary A continuous vegetable cooker was evaluated and shown to produce improved quality-cooked vegetables under more hygienic conditions as compared to batch type conventional cooking. The operating parameters for 85  ±  3% degree of cooking as optimal were determined for green peas, carrot, kohlrabi, and radish. The final product was evaluated in comparison to conventional cooking in terms of the degree of cooking and product quality (retention of chlorophyll, vitamin C and carotenoids; microbial analysis). The thermal efficiency of the cooker and specific energy consumption were compared with published data for steam blanchers.     

基于成熟值理论的蒜薹油炒过程品质变化动力学

油炒在中式烹饪中占主导地位,为考察在不同油温下食品品质随烹饪时间的变化规律及其动力学特性,采取油浴模拟油炒过程,对蒜薹的过热品质(维生素C、水分含量和红度值)进行反应动力学测定与分析。结果表明:蒜薹油炒中维生素C和红度值-a*变化均遵循一级动力学,水分含量变化遵循零级动力学;维生素C和红度值-a*的z值分别为76.92、83.33℃,水分含量在一级动力学下z值为62.50℃,均大于油炒蒜薹成熟的z值,满足烹饪优化前提;并指出水分对温度最为敏感,是烹饪工艺优化中的重要指标。本实验证明了蒜薹烹饪过程存在优化空间,为蒜薹油炒和中式烹饪过程优化处理提供了必要的动力学参数。     

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.     

Rice degree of milling effects on hydration,texture, sensory and energy characteristics. Part 1. Cooking using excess water

The purpose was to assess the effect of degree of milling (DOM) on cooking kinetics, sensory attributes, and energy requirements when cooking rice in excess water. Commercial milling equipment was adjusted to produce parboiled and non-parboiled rice samples that were milled to varying DOMs, including brown rice lots having no milling. Surface lipid content (SLC) ranged from 0.15% to 0.55% for non-parboiled rice and from 0.40% to 0.95% for parboiled rice. The percentage gelatinized kernels, moisture content, peak force and sensory attributes were determined as a function of cooking duration for all samples. The cooking duration required to attain ‘well-cooked’ rice was determined, after which the energy required for cooking was measured. Within the SLC range tested, DOM did not affect cooking kinetics, texture and flavor of rice. Non-parboiled brown rice required the most energy, expressed as energy per unit mass of uncooked rice, to be cooked, followed by parboiled brown, parboiled milled and non-parboiled milled rice.     

Cooking evaluation of crayfish (Procambarus clarkia) subjected to microwave and conduction heating: A visualized strategy to understand the heat-induced quality changes of food

The evaluation of food cooking process is an important way to understand the heat-induced quality changes and optimize the heating process. To understand the quality changes in crayfish tail heated by microwave (MW) and boiling water (BW), the protein denaturation, cooking uniformity and overheating degree of tails were visually evaluated based on the theories of reaction kinetics and maturity value in this work. Protein denaturation analysis showed that heat-induced protein denaturation in crayfish tails heated by MW and BW followed first-order reaction kinetics and had similar one-dimensional denaturation patterns and temperatures, but their distributions were non-uniform and with reverse trends. Moreover, strong correlations between protein denaturation degree and heat-induced qualities changes were observed in crayfish tail during heating. The cooking uniformity and overheating degree of crayfish tail heated by MW and BW were evaluated by the maturity value (M_v) and overheating value (O_v), respectively. Evaluations showed that the profiles of M_v and O_v in the crayfish tail were non-uniform and with reverse trends, and there was lower ΔM_v and ${\overline{\mathrm{O}}}_{\mathrm{v}}$ for crayfish tail heated by MW than by BW, but higher O_v occurred in the centre, which corresponded to the texture of crayfish tails heated by MW was more susceptible than by BW when proteins had completely denatured.Industrial relevanceThe general patterns of cooking process in crayfish tail during microwave heating and boiling have been visually evaluated and compared based on the theories of reaction kinetics and maturity value, which enriched the knowledge for the application of microwave in the industrial thermal processing of crayfish and reaction kinetics in the analysis of cooking (especially microwave heating). Furthermore, the theory of maturity value was introduced into the evaluation of the cooking uniformity and overcooked degree in crayfish tail during the heating, which provided a new strategy for the cooking evaluation of food.     

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.     

常见蔬菜的黄酮含量及烹饪对其含量的影响

本实验目的在于了解我国辽宁省地区常见蔬菜的黄酮类物质含量及黄酮类物质在不同烹饪方式下的变化情况,为进一步估算膳食中黄酮类物质的摄入水平提供依据。结果表明,叶菜中黄酮类物质含量较高,花、果类和根、茎类次之。萝卜缨、韭菜、芹菜中黄酮类物质含量较高,分别达到39.18,36.26和32.20mg/100g。经过烹饪后,大部分蔬菜中黄酮类物质含量均有所增加,其中,中火炒制的烹饪方式使蔬菜中的黄酮含量增加得较为显著,增加幅度在12.11%～166.38%之间。增加绿叶蔬菜的摄入量,可获得充足的黄酮类物质,采用中火炒制的烹饪方式有利于黄酮类物质的释放。     

Effects of Cooking in Solutions of Varying pH on the Dietary Fiber Components of Vegetables

To study the effect of pH on dietary fiber components of vegetables, beans, cauliflower, potatoes, peas and corn were cooked in buffers of pH 2, 4, 6, and 10. Water-soluble pectin and hemicellulose, water-insoluble pectin and hemicellulose, cellulose and lignin were quantitated in raw, cooked vegetables and cooking medium. Tenderness and pH of raw and cooked vegetables were determined. Texture varied with cooking medium. Cooked vegetables were most firm at pH 4 and softest at pH 10. Dietary components found in cooking medium reflected these textural changes. Vegetables which showed greater pH effects exhibited greater changes in fiber components.     

典型环境高镉地区常见蔬菜中镉的生物可及性及健康风险评估

为研究种植于典型环境高镉（Cadmium,Cd）地区的蔬菜对人体的健康风险,使用电感耦合等离子体质谱（ICP-MS）对种植于该区域的9种常见蔬菜中的元素（Mg、K、Ca、Cu、Zn）及重金属Cd进行检测,并研究蔬菜的烹调方式、消化过程和主要金属元素含量对Cd生物可及性的影响。同时,采用健康风险值（THQ）对膳食消费蔬菜暴露Cd的风险进行评估。结果表明,蔬菜样品中重金属Cd的平均含量范围为0.02~0.30 mg/kg。水煮可显著降低蔬菜中的Cd含量（P<0.05）,而生炒对蔬菜中的Cd含量未有显著影响（P>0.05）。对于生物可及性,水煮可显著提高蔬菜中Cd的生物可及性（P<0.05）,而生炒则无显著影响（P>0.05）。利用相关分析可知,Cd的生物可及性与K和Cu之间存在负相关关系（P<0.05）。若将Cd生物可及性纳入健康风险评估,仅高消费生菜人群的THQ大于1,提示当地居民消费蔬菜引起的健康风险较小。然而,仍需关注环境高镉地区其他膳食途径暴露Cd的慢性健康危害。因此,当地居民应选择消费低于Cd限量标准的蔬菜,并进行合理烹调以降低健康风险。     

Field Incurred Endosulfan Residues in Fresh and Processed Vegetables and Dietary Intake Assessment

Mitigation in endosulfan residues was determined in spinach, cauliflower, potato, brinjal, tomato, and okra by using different techniques. The endosulfan residues were determined in 66 samples of different vegetables, and it was found that the highest endosulfan residues (mg kg^?1) were at the raw stage in okra (1.71), brinjal (1.50), and spinach (1.16), respectively. The residue of endosulfan was lowest in potato (0.130) mg kg^?1. Washing reduced the endosulfan residue from 15 to 28%, peeling reduced it from 60 to 67%, and cooking further lowered it from 18 to 31% in all vegetables. Dietary intake assessment revealed that only samples of okra exceeded the maximum permissible intake value at the raw stage, whereas all the other samples were below maximum permissible intake value, although some were exceeding the maximum residue limits at the raw stage.     

Kinetics of hydration properties of meat emulsions containing various fillers during smokehouse cooking

The cooking kinetics of meat emulsions containing various fillers was determined by monitoring changes in hydration properties such as cooking loss and water-holding capacity during smokehouse cooking. Press juice, consumer cook test and emulsion stability of cooked product were also determined. The fillers used were buttermilk powder, corn starch, microcrystalline cellulose, modified corn starch, modified wheat flour, soy-protein concentrate and whey-protein concentrate. The cooking process was modelled using reaction kinetics and Eyring's absolute reaction rate theory. Enthalpy and entropy changes of activation were calculated for various properties and fillers.     

Steam Assisted Hybrid Cooking Behavior of Semitendinosus Muscle: Heterocyclic Amines Formation,Soluble Protein Degradation,Fat Retention,Surface Color,and Cooking Value

Beef (Semitendinosus muscle) was cooked in natural convection, forced convection and steam assisted hybrid oven and saturated steam oven at different oven temperatures until the geometric center of samples reached different end temperatures. Heterocyclic amine (HCA) compounds formation, soluble protein degradation kinetics, cook value, changes in fat content, surface colour and overall acceptance of cooked beef were determined. Soluble protein degradation of beef was considered as first order reaction kinetics and the reaction rate constants, k, were determined in the range of 0.014-0.052 min^?1. In steam assisted hybrid oven had higher reaction rate constants compared to that of the convection ovens. The effect of cooking temperature on soluble protein degradation for natural convection, forced convection and steam assisted hybrid oven followed the Arrhenius type of equation with activation energies of 12.45, 14.57 and 60.16 kJ/mol, respectively. Lower HCAs contents, shorter cooking times, lower cook values and lower fat retention were obtained by steam assisted hybrid oven cooking. Steam assisted hybrid cooking could be considered as an alternative cooking method to obtain a healthier product without compromising the eating habits of conventional methods due to better appearance (moderate burned surface) than saturated steam oven samples and a product retaining the most of the nutritional values.     

三种烹饪方式对蔬菜中维生素C含量的影响研究

目的:比较3种烹饪方式对8种蔬菜中维生素C含量的影响。方法:选取8种常见蔬菜,分别采用较新型烹饪方式(不锈钢炒锅加盖密闭式)、模拟传统烹饪方式(不锈钢炒锅不加盖)与传统烹饪方式(铁锅急火快炒不加盖)进行烹调,不添加食盐仅添加烹调油,严格控制其它烹饪条件。采用GB/T 5009.86—2003 2,4—二硝基苯肼法测定烹饪前后8种蔬菜中维生素C含量的变化。结果:相同条件下,采用3种不同烹饪方式对同种蔬菜进行烹调的结果显示,不同烹调方式都会造成蔬菜中维生素C损失,且维生素C含量与烹饪前相比,差异具有统计学意义(P<0.05)。新型烹饪方式与传统烹饪方式相比,蔬菜中维生素C含量较高,且据有显著性差异(P<0.05),新型烹饪方式组蔬菜中维生素C保存率最高(8种蔬菜分别为58.52%、73.21%、85.14%、68.66%、87.17%、82.78%、44.54%、74.91%);传统烹饪方式组蔬菜中维生素C保存率最低(对应上述8种蔬菜分别为29.26%、61.91%、52.58%、38.53%、43.58%、59.60%、24.66%、40.62%)。结论:不同烹饪方式对蔬菜中维生素C损失影响不同,新型烹饪方式对蔬菜中维生素C损失最小,保存率最高。     

Effect of steamable bag microwaving versus traditional cooking methods on nutritional preservation and physical properties of frozen vegetables: A case study on broccoli (Brassica oleracea)

The effect of steamable bag microwaving on the nutritional value and physical properties of frozen vegetables was studied and compared to that of traditional cooking methods (i.e., steamer steaming and traditional microwaving) for the first time. Broccoli was chosen for this study since it is one of the most consumed frozen vegetables. Titration, oxygen radical absorbance capacity assay, colorimetry (L*, a*, b*, hue angle, and total color difference) and texturometry were used for evaluation. The results show that steamable bag microwaving performs better than traditional microwaving and is equal to steamer steaming in retaining ascorbic acid content and increasing antioxidant activity compared to thawed frozen broccoli. Steamable bag microwaving tenderizes frozen broccoli faster, and better maintains the broccoli lightness and yellowness than steamer steaming and traditional microwaving. These findings show that steamable bag microwaving is a more appropriate cooking method for frozen broccoli than traditional cooking methods.Industrial relevanceSteamable bag microwaving is an emerging cooking technology for frozen vegetables. While steamable bag microwaving provides consumers with convenience and safety compared to other cooking technologies (i.e., traditional microwaving, steaming, and boiling), there is no information on the effect of steamable bag microwaving on nutritional and physical changes of frozen vegetables. Our findings show that steamable bag microwaving is more appropriate than traditional cooking methods and satisfies current consumers' needs better (i.e., high nutritional content, fresh-like produce, and time savings).     

Effect of water cooking on free phytosterol levels in beans and vegetables

Plant sterols (phytosterols) are known to decrease plasma cholesterol, mainly the atherogenic LDL cholesterol. In an earlier study, the thermal stability of phytosterols in vegetable oils was reported. The aim of this present work was to investigate the potential effect of cooking (30 min in boiling water), for eight plant products (broad bean, celery, cabbage, courgette, carrot, cauliflower, onion, pepper), on the free phytosterol level. Sitosterol was the most abundant sterol, followed by campesterol. After cooking, the level of total sterols was higher in all vegetables than that before cooking, if dry matter is considered. Acid hydrolysis (active for glycosylated phytosterols) yielded a higher sterol value than alkaline hydrolysis alone (active for esterified phytosterols). This indicated that studied vegetables contained appreciable amounts of steryl glycosides. Their cooking induced higher values of free phytosterols. Cooked vegetables could give better protection against cardiovascular diseases thanks to higher phytosterol levels.     

Effect of different cooking methods on the antioxidant activity of some vegetables from Pakistan

The effects of different cooking methods (boiling, frying and microwave cooking) on the antioxidant activity of some selected vegetables (peas, carrot, spinach, cabbage, cauliflower, yellow turnip and white turnip) were assessed by measuring the total phenolic contents (TPC), reducing power and percentage inhibition in linoleic acid system. TPC (gallic acid equivalents g/100 g of dry weight) and reducing power of the methanolic extracts of raw‐, microwaved‐, boiled‐ and fried vegetables ranged 0.333–2.97, 0.52–2.68, 0.48–2.08, 1.00–2.02 and 0.391–2.24, 0.822–1.10, 0.547–1.16, 0.910–4.07, respectively. The level of inhibition of peroxidation ranged 71.4–89.0, 66.4–87.3, 73.2–89.2 and 77.4–91.3%, respectively. Antioxidant activity of the vegetables examined was appreciably affected because of varying cooking treatments. TPC of vegetables, generally, decreased by boiling, frying and microwave cooking. There was a significant (P < 0.05) increase in reducing power as a result of frying. However, boiling and microwave cooking did not affect reducing power. Inhibition of peroxidation increased by boiling and frying, whereas, in contrast it was decreased by microwave cooking. The results of the present investigation showed that all the cooking methods affected the antioxidant properties of the vegetables; however, microwave treatment exhibited more deleterious effects when compared with those of other treatments. Thus an appropriate method might be sought for the processing of such vegetables to retain their antioxidant components at maximum level.     

High Performance Liquid Chromatographic Determination of Carbohydrates in Raw and Cooked Vegetables

The soluble sugar contents of 17 raw and cooked vegetables were determined by TLC and HPLC. In general, the soluble carbohydrate content of vegetables is low. For raw materials the highest content was found in carrot, red cabbage, egg plant, green bean and leek. Upon cooking the glucose, fructose and total sugar contents decrease and this diminution is more drastic in the case of frying. The amount of sucrose, except in the case of carrot, egg plant and green bean, increases with cooking. The maltose content of the broad bean increases in the culinary process.     

Kinetics of pH and colour of meat emulsions containing various fillers during smokehouse cooking

The cooking kinetics of meat emulsions containing various fillers was determined by monitoring changes in pH and colour during smokehouse cooking. The fillers used were buttermilk powder, corn starch, microcrystallline cellulose, modified corn starch, modified wheat flour, soy-protein concentrate and whey-protein concentrate. The cooking process was modelled using reaction kinetics and Eyring's absolute reaction rate theory. Enthalpy and entropy changes of activation were calculated for various properties and fillers.     

Nitrate and nitrite contents of some fresh and processed Egyptian vegetables

The nitrate and nitrite contents of sixteen fresh vegetables, widely consumed in Egypt, were determined. The highest values of nitrate were observed in leafy vegetables, followed by root vegetables and then pulses. Of the leafy vegetables, spinach, roquette and chard contained the highest concentration of nitrate. Nitrite concentrations were detected at low levels in a few samples, while the others were free of nitrite.Cooking had the effect of lowering the levels of nitrate in all types of fresh vegetables studied; no nitrite was formed during cooking.Storage of frozen vegetables for six months decreased the levels of nitrate, while nitrite was formed at low levels after storage for three or four months.     

烹制方法对猪肉脂质氧化和挥发性风味物质的作用研究

研究对比了4种烹制方法(煮制、烤制、微波及油炸制(大豆油、花生油和葵花油))对猪肉脂质氧化及挥发性风味成分的影响。结果表明:烹制能够促进猪肉的脂质氧化,经不同方式烹制后,熟制猪肉的过氧化值(POV)和硫代巴比妥酸值(TBA)显著增加(P0.05)。不同熟制猪肉之间脂质氧化程度存在显著性差异(P0.05),其中烤制猪肉的脂质氧化程度最高,其次为微波和水煮,而炸制猪肉的氧化程度最低。气相色谱-质谱(GC-MS)联用技术从熟制猪肉中共分离鉴定出68种挥发性风味成分,主要包括醛类、脂肪烃类、醇类、酮类、酯类等,总挥发性风味化合物含量在221.09(大豆油炸制猪肉)-1084.61 AU×106/g(煮制猪肉)之间。醛类是主要的化合物,占总挥发性风味成分的73.78(葵花油炸制猪肉)-78.79%(烤制猪肉),而己醛是最主要的醛类物质。TBA值与醛类、醇类及总挥发性风味物质呈显著正相关(p0.05),而POV值与挥发性风味物质的相关性不显著(p0.05)。主成分分析法(PCA)能够很好地区分经不同烹制方法得到的熟猪肉。