Water Holding Capacity of Hemicelluloses from Fruits, Vegetables and Wheat Bran

The water-holding capacities of freeze-dried bean, cabbage, lettuce, onion, peach, pear, pumpkin, tomato, wheat bran and their hemicelluloses were determined by the centrifugation method. Cabbage had the greatest water-holding capacity at 35.8g of water per gram of dry food; bran the lowest at 5.2g water per gram. The waterholding capacity (WHC) of the hemicelluloses from fruits and vegetables varied considerably from 3.3 g/g in beans to 12.0 g/g from cabbage. Hemicelluloses extracted from wheat bran showed a marked increase in WHC from 5.2 g/g of water per gram of‘whole’bran to 22.8 g/g for hemicellulose. This decreased to 15.3g of water bound by hemicellulose that had been extracted after chlorite delignification. WHC of hemicelluloses from wheat bran and cabbage may account for their ability to increase stool weight.     

果蔬食品体外抗氧化方法研究进展

食用果蔬食品可以有效降低多种疾病的发生率,抗氧化能力是重要原因.抗氧化物质清除自由基的机制主要有氢原子转移(HAT)和单电子转移(SET)2种.本文具体介绍了ORAC法、TRAP法、PCL化学发光法、β-胡萝卜素亚油酸体系、LDL低密度脂蛋白氧化方法、福林酚法、ABTS清除自由法、DPPH清除自由基法、FRAP法.并结合实例介绍果蔬食品体外抗氧化方法研究进展,对抗氧化方法的标准化进行了展望.     

Natural Occurrence of Undecaenes in Some Fruits and Vegetables

1-(E,Z)-3,5-undecatriene and 1-(E,Z,Z)-3,5,8-undecatetraene were isolated under enzyme inhibition from edible parts of peach, passion fruit, and kiwi; the triene only was found in celery, parsley, mandarine, apple and pear. Capillary gas chromatography, sniffing-capillary gas chromatography, and combined “live”-capillary gas chromatography-mass spectrometry of the concentrated liquid-liquid extracts were used to establish their identity. Owing to their ultra-low odor detection thresholds and the proposed biogenesis, these trace compounds may be “character impacts” in a wide variety of food flavors of plant origin.     

Water-Holding Capacity and Textural Acceptability of Precooked, Frozen, Whole-Egg Omelets

Precooked, frozen omelets were analyzed for moisture loss, expressible moisture, shear-force, and sensory evaluation to determine water-holding capacity and- textural acceptability. Addition of 0.1% xanthan gum, application of moist heat in cooking, and cryogenic freezing with liquid carbon dioxide or nitrogen minimized moisture loss and shear force. Sodium. carboxymethylcellulose (CMC), pre-gelatinized tapioca starch and sodium tripolyphosphate additives performed satisfactorily, but omelets containing xanthan gum were consistently rated highest in sensory evaluation of several treatments, including fresh and untreated control omelets. Steaming omelets for five minutes combined with cryogenic freezing produced a desirable- omelet, requiring no additives. Steamed omelets were rated comparable to baked omelets in most sensory parameters.     

蓝莓等10种果蔬提取物体外抗氧化活性的比较

采用铁离子还原/抗氧化力测定法(ferric reducing/antioxidant power assay,FRAP)、邻苯三酚法、水杨酸法,比较猕猴桃、龙眼、蓝莓、大枣、南瓜、冬瓜、菠菜、芹菜、苦瓜、木耳10种果蔬提取物的总抗氧化力、清除超氧阴离子(O2-·)及清除羟自由基(·OH)能力.结果显示,上述10种果蔬提取物的总抗氧化力按由强到弱的排序依次为:蓝莓>大枣>龙眼>南瓜>苦瓜>木耳>猕猴桃>芹菜>菠菜>冬瓜;清除超氧阴离子(O2-·)的能力依次为:龙眼>南瓜>菠菜>蓝莓>大枣>芹菜>冬瓜>苦瓜>木耳>猕猴桃;清除羟自由基(·OH)的能力依次为:猕猴桃>蓝莓>芹菜>菠菜>木耳>大枣>龙眼>冬瓜>苦瓜>南瓜.     

一些果蔬对活性自由基和亚硝酸盐的消除作用

对29种新鲜水果和蔬菜的一般营养成分和过氧化物酶、过氧化氢酶活性以及对H_2O_2和NaNO_2的消除能力进行了测定。结果表明,在模拟胃液条件下,各种供试的新鲜果蔬对活性氧自由基和亚硝酸盐均具有不同程度的消除能力,其消除量与新鲜果蔬中的蛋白质含量呈极显著正相关。谷胱甘肽、还原型辅酶Ⅰ、维生素E、维生素C和半胱氨酸等还原性食品成分对NaNO_2和H_2O_2都有良好的线性消除关系。煮沸处理后,有机酸含量高的果蔬对NaNO_2和H_2O_2的消除能力增强,有机酸含量低时,其消除能力下降。提示果蔬对活性氧自由基和亚硝酸盐的消除能力取决于果蔬中还原性食品成分的种类、含量及其氧化还原特性。     

Explosion Puffing of Fruits and Vegetables

Explosion puffing is a processing system which facilitates hot air drying of fruits and vegetables. Explosion puffed foods are easily rehydrated and have excellent sensory properties. The process costs are similar to the cost of conventional hot air drying. Previous publications have reported the results relevant to carrots, potatoes, apples, and blueberries. Sufficient research has been done on other fruits and vegetables to establish that they, too, can be satisfactorily explosion puffed and dried to yield a good product. The processing conditions for explosion puffing of mushrooms, celery, onions, peppers, rutabagas, beets, yams, pears, pineapples, strawberries, and cranberries are presented.     

ABTS法体外测定果蔬类总抗氧化能力的研究进展

ABTS法作为一种用于体外测定物质总抗氧化能力的新方法,在国内报道甚少,文中就该方法在国外的发展、在果蔬中的应用以及存在的问题进行了概述和分析,为该方法在国内的应用提供理论依据。     

欧盟果蔬食品安全标准体系研究

欧盟已经建立了一套比较完善的技术法规和标准体系，该体系以颁布技术法规为主，辅之以技术标准的制定。欧盟制定果蔬食品安全标准的相关机构有欧盟委员会、欧共体理事会和欧洲标准化委员会（CEN）。欧盟果蔬食品安全标准体系包括果蔬食品卫生标准，果蔬食品试验、检验、检疫方法标准，果蔬食品安全控制与管理技术标准，果蔬食品包装标签、标识标准，特定食品产品标准。     

Osmotic Dehydration of Tropical Fruits and Vegetables

Because of the microstructural complexity of plant tissue, osmotic dehydration cannot simply be explained as a pure osmotic process in which cell membranes act as a semipermeable barrier allowing water to pass through. Instead, osmotic dehydration is considered a process in which many simultaneous mechanisms, acting at different levels, are responsible for mass transport. Different compositional and structural profiles are induced in fruits and vegetables, depending on process variables and the tissue microstructure. Compositional-structural profiles that are developed with gas-liquid exchanges in the tissue during osmotic process have a significant impact on physical (optical), textural and chemical properties (e.g., flavour profile) of the final product, which is in part influenced by the differences in the number of cells that are altered and unaltered during the treatment. This review focuses on changes in the physical, chemical, and cellular structure of fruits and vegetables, some technologies commonly applied to increase mass transfer during osmotic dehydration (OD), potentials and industrial applications of OD, and the challenges of osmo-drying technology.     

Gloss Evaluation of Curved-surface Fruits and Vegetables

Gloss measurements are used to evaluate the quality and appearance of a product, especially in cases where esthetic appearance is of importance. Most commercial glossmeters are designed for measuring products of flat surface and therefore are not suitable for food products because of their uneven, curved surface. A new generation of commercial glossmeters is recently available for confined areas, curved surfaces, and surfaces that are not uniform. This article provides a brief review of gloss measurement principles and methods for fresh fruits and vegetables. It reports on the gloss measurement of apples and other fresh products using a commercial glossmeter and a specially designed spectrometer-based gloss measurement prototype integrated with imaging and automatic sample positioning capabilities. Results showed that the prototype had a nonlinear relationship with standard gloss measurements. With the new setup, the gloss of apples was measured with the repeatability for 90% of the measurements being better than 16%, calculated as the ratio of the difference between maximum and minimum gloss values to the mean value in percent. Further research is needed to simplify the imaging/mechanical configuration and improve the coordinate calculation algorithm to achieve more accurate, repeatable gloss measurements.     

Protein Nutritional Quality of Traditional and Novel Cowpea Products Measured by In Vivo and In Vitro Methods

Effect of processing on nutritional quality of cowpea meal protein was determined by in vivo and in vitro methods. Uncooked meal and meal which had been extruded at various temperatures and moistures; slurried, steamed, and drum-dried (SDP); and hydrated to a paste and deep-fat fried (akara) were studied. PER values of extrudates (1.81–1.97), and akara (1.89) were higher than those of raw meal (1.44) or steamed, drum-dried paste (1.63). The saturation kinetics model showed similar trends but differences were not significant. In vitro digestibility was highest for extrudates (83–85%), intermediate for akara and SDP (82.8%, 81.2%), and lowest (77.8%) for raw meal. C-PER/DC-PER gave differing and contradictory results.     

HACCP体系在果蔬保鲜处理过程中的应用

为了确保果蔬食用的安全性、有效延长保鲜期,通过对果蔬保鲜处理过程中的各个环节可能潜在的危害进行生物性、化学性和物理性分析得出关键控制点。应用HACCP七个步骤确定果蔬保鲜过程中的关键控制点及关键限值,制定相应纠偏措施和关键控制点的监控方法,有效地预防了潜在危害对果蔬的污染,最大程度地确保产品的安全与卫生,从而为HACCP在果蔬加工生产中的应用提供了有力的参考依据。     

常见果蔬的抗氧化方法研究进展

综述了常见果蔬的抗氧化机理以及果蔬中抗氧化物质的测定方法,通过研究果蔬的抗氧化能力找到优良的抗氧化物质。     

Determination of Lysozyme in Raw Fruits and Vegetables

Several fresh fruits and vegetables were tested for lysozyme activity. The produce was weighed, diced, blended for 2 min and filtered through a cheesecloth. The filtrate was centrifuged at 2,000 x G for 15 min. The supernatant juice was clarified and stored frozen until the spectrophotometric assay was completed. Crystalline eggwhite lysozyme was used as a standard. Average lysozyme concentrations per ml of the juice were: cauliflower 32.5 μg, rutabaga 13.0 μg, papaya 5.0,μ cabbage 2.7μ, kohlrabi 2.4 μg, and red radish 2.2 μg Lysozyme (0.5-1.8 μg) was also detected in white radish, turnip, parsnip, and broccoli. Other vegetables and fruits tested showed no detectable lysozyme.     

果蔬保鲜剂特克多的合成

果蔬生产有很强的地域性和季节性，有很多果蔬在加工、储运过程中常常发生霉变、腐烂、鲜度下降。因此开发果蔬保鲜剂以提高果蔬品质、延长上市周期的研究备受人们关注。     

果实和蔬菜中的过氧化物酶

介绍了果实和蔬菜中过氧化物酶催化的反应 ,过氧化物酶的底物、最适 p H和最适温度 ,过氧化物酶的热失活与酶的恢复和再生 ,过氧化物酶的化学物质抑活。     

我国有机果蔬产业发展问题及对策

<正>中国是世界果蔬产品的生产大国,但其出口量却始终未能名列世界前茅。另外,中国的水果产品参与国际化贸易的水平较低。出口量仅占产量的2％, 远低于国际9％-10％的平均水平。欧美的市场准入与认证制度、重重绿色贸易壁垒,使中国刚刚蕴育的有机果蔬产品在出口方面遭遇雪雨风霜;而国内市场     

Response of the Phenomena of Extract-Release Volume and Water-Holding Capacity to Irradiated Beef

SUMMARY— Beef irradiated at levels from 0.3 to 2.4 Mrads with cobalt-60 showed much greater changes in extract-release volume than water-holding capacity measured by the filter paper press method. The difference was even greater after storage at 5°C for 30 days. This difference appears to be a consequence of the greater amount of meat shrinkage after irradiation. Meat shrinkage increased both with increased levels of radiation and time of holding.     

A Critical Review of Dehydrofreezing of Fruits and Vegetables

Freezing is a very well established food preservation process that produces high-quality nutritious foods that offer the advantage of a long storage life. However, freezing is not suitable for all foods, and freezing does cause physical and chemical changes in many foods that are perceived as reducing the quality of the thawed material. Many innovative freezing processes are currently being researched and developed throughout the world to overcome these problems. One of these is dehydrofreezing. Dehydrofreezing is an adjunct to freezing in which a food is first dehydrated to a desirable moisture content and then frozen. It is particularly suited to fruits and vegetables. Since fresh fruits and vegetables contain more water than meat, and their cellular structure is less elastic, they are prone to more damage during freezing than meat. Removing some of the water prior to freezing theoretically allows the ice crystals to form and expand without damaging the cellular structure. Reducing the water content prior to freezing also has the potential to reduce the freezing time, the initial freezing point, and the amount of ice formed within the product. Despite being often cited as a new, novel or emerging technology, the concept of dehydrofreezing was developed in the 1940s. However, it has remained a niche process being commercially applied to products such as potatoes, carrots, and onions. In recent years there has been renewed interest in dehydrofreezing, and this review looks at the most recent innovations in dehydrofreezing research.