果胶制备方法的研究进展

果胶在食品，医药和其它行业应用非常广泛，市场需求量大，而传统的酸提醇沉的制备方法有许多缺点，本文就近年来的一些制备果胶的方法进行了总结。     

Utilisation of orange by-products—orange peel carotenoids

Carotenoids were extracted from fresh orange peel with various solvents. Acetone was the most efficient of the solvents tested. Two successive extractions with acetone after an initial washing with either acetone or methanol were adequate to remove 89% of the total carotenoids. The extracts were concentrated, the carotenoids transferred to hexane and a crude pigment concentrate was obtained by hexane evaporation. Water washings prior to acetone extraction eliminated the solvent-solvent transfer to hexane. The extraction residue was used for pectin recovery. Carotenoid removal from the peel did not affect the yield and quality of the pectin.     

新型尿素吸附剂——果胶铜凝胶球的吸附性能

用铜离子交联果胶制得果胶铜凝胶球,用红外光谱和扫描电镜初步表征其结构,并研究果胶铜凝胶球对尿素的吸附性能。分别考察了果胶浓度、铜离子浓度、吸附时间、温度和尿素浓度对吸附的影响。结果表明:303K时,果胶铜凝胶球对尿素的吸附反应在7h时达平衡,当果胶浓度为2.5%,氯化铜浓度为2.0%,尿素浓度为400mg/L时,吸附量为48.63mg/g。吸附等温线符合Freundlich方程,温度过高和过低对吸附均不利。     

紫薯中果胶提取工艺条件的研究

以紫薯为原料,由红外光谱分析确定紫薯提取物为果胶,考察提取时间、提取温度、酸碱度因素的影响,通过单因素试验和正交实验研究酸解法确定紫薯果肉中提取果胶的最佳优化工艺。实验结果表明,在p H值为2.50,提取温度为95℃,提取时间为1.0 h的条件下,果胶提取率最高为15.23%。将得到的紫薯果胶通过活性炭脱色、干燥处理,得到质量较好的果胶产品。     

Characterization of Cell Wall Enzyme Activities, Pectin Composition, and Technological Criteria of Strawberry Cultivars (Fragaria×ananassa Duch)

ABSTRACT: The effects of physical characteristics and cell wall enzymatic activities of several strawberry culti-vars were investigated for possible industrial use. The enzymes study showed that the softest varieties had the highest pectin methylesterase (PME) and polygalacturonase (PG) activities. Differences in alcohol-insoluble pectin, water-soluble pectin, and parietal residue compositions were observed between Darsanga ("firm fruit") and Senga sengana ("soft fruit"). Finally, the study of pectin composition of Darsanga and Senga sengana indicated that the softest fruit had the highest water-soluble pectin content. The measurement of fruit PME activity permitted a preliminary screening of fruit maturity characteristics.     

Quality-Related Enzymes in Plant-Based Products: Effects of Novel Food-Processing Technologies Part 3: Ultrasonic Processing

High-power ultrasound is a versatile technology which can potentially be used in many food processing applications including food preservation. This is part 2 of a series of review articles dealing with the effectiveness of nonthermal food processing technologies in food preservation focusing on their effect on enzymes. Typically, ultrasound treatment alone does not efficiently cause microbial or enzyme inactivation sufficient for food preservation. However, combined with mild heat with or without elevated pressure (P ≤ 500 kPa), ultrasound can effectively inactivate enzymes and microorganisms. Synergistic effects between ultrasound and mild heat have been reported for the inactivation of both enzymes and microorganisms. The application of ultrasound has been shown to enhance the rate of inactivation of quality degrading enzymes including pectin methylesterase (PME), polygalacturonase (PG), peroxidase (POD), polyphenol oxidase (PPO), and lipoxygenase (LOX) at mild temperature by up to 400 times. Moreover, ultrasound enables the inactivation of relatively heat-resistant enzymes such as tomato PG1 and thermostable orange PME at mild temperature conditions. The extent to which ultrasound enhances the inactivation rate depends on the type of enzyme, the medium in which the enzyme is suspended, and the processing condition including frequency, ultrasonic intensity, temperature, and pressure. The physical and chemical effects of cavitation are considered to be responsible for the ultrasound-induced inactivation of enzymes, although the dominant mechanism depends on the structure of the enzyme.     

Methods for the preparation of cell walls from potatoes

A group of new methods is described for preparing cell walls from potatoes and processed potato products. Starting from raw domestic potatoes, starch is degraded enzymatically after a very brief 100 °C gelatinisation step conducted after homogenisation to minimise the time required for heat transfer. Protein is removed by detergent and phenol extraction. This procedure (method 1) gave cell wall preparations containing <5% starch, with minimal degradation of wall polysaccharides. It did not, however, remove starch efficiently from industrial potatoes in which the starch content is much higher. A different procedure, method 2, was used in this case. In method 2 a 20 min starch gelatinisation step was used but the temperature was restricted to 70 °C and the pH to 4.0, with the aim of protecting pectins from depolymerisation. Method 2 and method 1A, which is a hybrid procedure involving the starch gelatinisation step from method 2 and other steps from method 1, gave low‐starch cell walls from industrial as well as domestic potatoes. These methods are suitable for a range of potato types and potato products and are either more efficient or more convenient than previous procedures for cell wall isolation. © 2002 Society of Chemical Industry     

火棘果实中油、色素及果胶的联产工艺研究

对火棘果实中油、色素及果胶的提取提出了联产工艺研究，火棘种了、果肉中的油脂利用超临界二氧化碳萃取技术萃取，水溶性火棘红色素、果胶利用溶剂法提取。并对实验结果进行分析。     

果胶制备的研究进展

介绍了果胶的化学结构及其原料，并结合国内外多年的研究成果，综述了果胶的提取、浓缩、沉淀和干燥的方法。     

Physicochemical,carbohydrate and sensory characteristics of highbush and rabbiteye blueberry cultivars

The chemical composition, colour and texture of fresh berries from three rabbiteye (‘Climax’, ‘Premier’ and ‘Tifblue’) and two highbush (‘Bluecrop’ and ‘Jersey’) blueberry cultivars were measured. Shear (482 vs 290 N), compression (6.50 vs 3.96 N) and puncture forces (1.48 and 0.85 vs 0.81 and 0.43 N) were higher (P ≤ 0.05) for rabbiteye than for highbush cultivars. Shear for ‘Bluecrop’ blueberries averaged 254 N, whereas for ‘Climax’ it was 565 N. The puncture force required to penetrate the skin was lower for ‘Bluecrop’ (0.78 N) and ‘Jersey’ (0.83 N) and higher for ‘Climax’ (1.71 N). However, sensory panellists found no differences (P > 0.05) in colour, flavour or skin toughness among the five cultivars. ‘Climax’ was rated lower in seediness. Rabbiteye cultivars contained more fibre and complex polysaccharides than highbush cultivars. These differences in complex carbohydrates that make up the cell wall layers may contribute to the toughness of rabbiteye cultivars and their possible longer fresh shelf‐life, though taste panellists did not find this toughness objectionable. Copyright © 2005 Society of Chemical Industry