原果胶酶提取桔柚皮中果胶的研究

利用微生物原果胶酶酶法提取果胶，可克服工业酸法生产的诸多不足并得到质量稳定的果胶产品。将Aspergillus sp XZ-131菌株振荡培养3d，过滤得到原果胶酶粗酶液。将其处理桔柚皮，研究不同反应时间、温度、pH值、料液比对原果胶酶作用原果胶，释放果胶的影响。研究结果表明：最佳条件是25℃、pH3．0、料液比1：2和反应5h。在此反应条件下果胶产率达35．7％。     

果胶酶及其在果蔬汁加工中的应用

果胶酶普遍存在于细菌、真菌和植物中，是分解果胶类物质的多种酶的总称，在果蔬加工、饲料、纺织和造纸工业中应用非常广泛。介绍了果胶的组成和结构，论述了果胶酶的分类、作用机制及酶活测定方法，并对果胶酶在果蔬汁加工中的应用等方面进行综述。     

果胶酶在果蔬加工中的应用

果胶酶是指分解果胶类物质的多种酶的总称。通常包括原果胶酶、果胶甲酯水解酶、果胶酸酶。果胶酶普遍存在于细菌、真菌和植物中,在果蔬加工、饲料、纺织和造纸业中应用非常广泛。本文对果胶酶的来源、分类、作用机制及其在果蔬加工中的应用等方面进行综述。     

果胶酶在果蔬汁加工中的应用研究进展

果胶酶是一种能够分解果胶物质的复合酶。作为世界四大酶制剂之一,果胶酶已被广泛应用于果蔬汁加工、酿酒以及天然产物的提取等食品行业中。在收集和整理相关资料的基础上,介绍了果胶的组成和结构,论述了果胶酶的分类及其作用机理,着重对近年来果胶酶在果蔬汁加工中的应用研究进展作了较为全面的综述,并对国内果胶酶的生产存在的问题以及未来的研究方向进行了讨论,以期为今后的研究以及实践提供参考。     

微生物果胶酶的研究进展

果胶酶是一类分解果胶质的酶的总称。果胶酶分布很广，主要存在于高等植物和微生物中。在果胶酶中，原果胶酶、聚半乳糖醛酸酶、裂解酶和果胶酯酶得到了广泛深入的研究。果胶酶在当前的生物工程领域中起着非常重要的作用。主要论述了果胶酶的分类、结构、检测方法以及物理化学和生物学特性，并且简要概述了其在工业生产中的应用。     

碱性果胶酶的应用进展

碱性果胶酶分解复杂的果胶成小分子如半乳糖醛酸。碱性果胶酶在茶和咖啡发酵、纺织和植物纤维加工、油提取、含果胶工业废水处理等领域具有广泛应用。最近有些有关碱性果胶酶应用于造纸、植物病毒纯化、诱导植物抗病、家禽饲料、洗涤剂等领域的报道。综述了碱性果胶酶在各个领域中的应用。     

果胶酶在葡萄酒生产中的应用

近几十年，葡萄酒生产者开始深入研究，采取许多人为控制条件，以加速生产过程，提高产品质量。在研究中发现葡萄的成熟、乙醇的生成、苹果酸——乳酸的发酵以及葡萄汁、葡萄原酒的澄清等都是由许多酶作用的结果，酶影响着葡萄酒酿造中各个重要环节。因而，近十几年果胶酶的开发与应用给葡萄酒生产带来许多有益之处。1．果胶酶的作用机理如其它水果一样，葡萄中存在着大量果胶，它们起着细胞粘合剂的作用。果胶是由半乳糠醒组合的大分子，并与不同的多糖连在一起，果胶物质与纤维素、半纤维素以及木质素是细胞壁最重要的构成物质（见图2）。…     

微生物果胶酶的研究进展

果胶酶(pectinases)是指能协同分解果胶质的一组酶的总称,主要包括聚半乳糖醛酸酶(PG)、果胶裂解酶(PL)和果胶酯酶(PE)等,广泛应用于食品工业、饲料工业、造纸工业和纺织工业.近年来,随着我国国家政策和产业结构的调整,果汁和果酒行业得到迅猛发展.果胶酶作为果汁加工的重要酶制剂,市场需求量巨大.果胶酶生产普遍采用微生物发酵法,本文主要概述并比较了国内外微生物发酵法生产果胶酶的研究和应用情况.对国内果胶酶生产菌种的选育、微生物产果胶酶的发酵工艺及培养条件等进行了重点阐述,并简要介绍了微生物果胶酶的酶学性质和果胶酶的固定化情况.旨在发现当前我国果胶酶研究和开发中存在的问题,明确今后我国果胶酶研究中的前进方向,为研究和开发出同国际接轨的新型、高效果胶酶提供参考.     

果胶酶活性的测定方法

果胶酶活性的测定方法□孙越果胶是以原果胶、果胶和果胶酸三种不同形态存在果实组织中。未成熟的果实中的果胶物质大部分以原果胶的形式存在，不溶于水，与纤维素等将细胞与细胞紧紧地结合在一起，果实显得坚实脆硬。随着果实的成熟，原果胶在原果胶酶的作用下，分解成为...     

果蔬贮藏保鲜过程中果胶酶变化的研究进展

果胶是植物细胞壁胞间层的主要成分,果胶酶存在于天然植物组织中,可以催化果胶分解,进而破坏细胞壁的完整性,使得果蔬硬度下降。在贮藏过程中影响果蔬软化的因素主要有乙烯、Ca2+及温度等。常见的果蔬保鲜技术包括有物理、化学及生物保鲜技术,不同的保鲜技术对果蔬软化的机制不同。本介绍了果胶的结构及果胶酶的分类,同时总结了影响果胶酶活性的主要因素及其常见贮藏保鲜技术对果胶酶的影响,为果蔬贮藏保鲜过程中抑制软化的研究奠定理论基础。     

Effect of different pre-fermentation treatments on polyphenols,color, and volatile compounds of three wine varieties

Wines produced by three different grape varieties were treated with seven pre-fermentation techniques to analyze their variation in polyphenolic compounds, color parameters, and aromatic components. For polyphenolic compounds and color parameters, a better result was obtained after the grape pulp treatment, with the maximum impact observed after joint treatment with thermovinification and pectolytic enzymes, followed by thermovinification and cold soak, while pectolytic enzymes treatment alone was ineffective, resulting in almost no effect. On the contrary, the application of thermovinification and cold soak treatments before crushing the whole juice led to a dramatic decline in most indexes. For aromatic components, the joint treatment of thermovinification and pectolytic enzymes on grape pulp significantly affected its amount and type, in addition to giving the wine a mellow aroma.     

Regulation of the expression of endopolygalacturonase gene PGU1 in Saccharomyces

Previous work in our laboratory has shown that Saccharomyces bayanus strain SCPP is the only reported yeast expressing the three types of pectolytic enzymes: pectin esterases, pectin lyases and polygalacturonases. One of these enzymes, the endopolygalacturonase (endoPG), hydrolyses plant-specific polysaccharide pectin. The endoPG encoding gene (PGU1) is also present in Saccharomyces cerevisiae. It has been shown that this endoPG is required for the development of pseudohyphae. Using genomic DNA, the PGU1-1 and PGU1-2 promoters of these strains have been amplified and used to construct gene fusions with the beta-galactosidase gene. On the basis of beta-galactosidase measurements, we compared the expression of both promoters in different environmental conditions in order to identify their modulation. We have shown that the PGU1 gene is upregulated by the presence of the pectin and the product resulting from endopolygalacturonase activity. Moreover, expression of the PGU1 is also enhanced under respiratory and filament formation conditions.     

Effect of UV-LED irradiation processing on pectolytic activity and quality in tomato (Solanum lycopersicum) juice

The aim of this research was to analyze pectolytic activities (pectinmethylesterase “PME” and polygalacturonase “PG”) and physical qualities in tomato juice treated by UV-LED, Hot Break (HB), and Cold Break (CB) processing. Tomato juice treated by UV-LED (117 mJ/cm²) obtained a residual PME activity similar to that of CB, and tomato juice treated by UV-LED (351 mJ / cm²) had a residual PME activity 28.3% lower than HB (p < 0.05). The effect of UV-LED on PG activity was similar to HB and 49% lower than CB (p < 0.05). Furthermore, UV-LED processing caused a decrease in pH and total acidity and a significant increase in total lycopene content. Antioxidant activity and viscosity for UV-LED processing were similar to CB, total polyphenol content and °Brix were similar to HB (p > 0.05). Therefore, this study provides a promising application of UV-LED technology for controlling enzymatic activity in tomato juice, and an alternative to heat treatment.Industrial relevanceNowadays, the tomato industry uses heat treatments to inactivate pectolytic enzymes. UV-LED technology could have an industrial appreciation, as it was efficient in decrease the activity of these enzymes, in addition, preserved and increased some bioactive compounds. Therfore, it is proposed as an efficient method for processing fruit and vegetable juices. Nevertheless, further studies are needed to clarify the effect of this technology on pectolytic enzymes and quality parameters in liquid fruit and vegetable foods.     

Influence of processing on the rheological properties of tomato paste

This paper deals with the influence that some processing variables (sieve pore size and breaking temperature) and tomato variety exert on the linear viscoelastic properties of tomato paste. With this aim, 16 tomato paste samples from four different varieties (with different contents of the pectolytic enzymes polygalacturonase and pectin methylesterase) have been manufactured at different breaking temperatures (65–85 °C) and screen sizes (0.8–2.2 mm). From the experimental results obtained, we conclude that tomato paste behaves as a weak gel, showing a wide plateau region in its linear relaxation spectrum. The linear viscoelastic properties of tomato paste depend dramatically on water‐insoluble solids content and particle size, which may be greatly influenced by processing variables. Nevertheless, the specific action of the above‐mentioned pectolytic enzymes must also be taken into account. © 2002 Society of Chemical Industry     

Immobilisation of pectinases into PVA gel for fruit juice application

In this study, for the first time, the use of polyvinyl alcohol gel in the form of LentiKats^® to immobilise pectinase was investigated and its application in fruit juice clarification was evaluated. Six pectolytic enzymes were tested for their polygalacturonase (PG) and pectin lyase (PL) activities. Panzyme YieldMASH and Panzyme Smash XXL exhibited maximum PG and PL activity, respectively (P < 0.05), in free and immobilised forms. The immobilised enzymes revealed a good adaptability to an acidic solution like fruit juice. Moreover, the immobilised Panzyme YieldMASH and Panzyme Smash XXL retained about 60% and 74% residual activity, respectively, in the second cycle and more than 30% during the third cycle. After that, both immobilised enzymes retained about 20% of their initial activity after repeating eight times without a significant decrease in the observed activity. The best result in terms of turbidity reduction was obtained in apple juice with immobilised Panzyme YieldMASH (about 80%), and the same % of turbidity reduction was successfully retained in the two following uses.     

Evaluation of pectolytic activities of enological interest in industrial enzyme preparations

 The purpose of this research was to determine the activity of several pectolytic enzymes, such as pectin methyl esterase, endopolymethylgalacturonase, endopolygalacturonase, exopolymethylgalacturonase, endopolygalacturonase, pectin transeliminase and pectic acid transeliminase, from within preparations that are available on the Portuguese market. The selected preparations were as follows: 15 pectolytic enzyme preparations, one hemicellulolytic preparation and one glucanase preparation. The measurements of enzyme activity were carried out using model solutions with 50 mg·l^–1 SO₂, pH 3.2, 25°C, with and without 12% ethanol (v/v), and a 24-h incubation period. Quantitatively, the results proved to be heterogeneous, significantly varying from preparation to preparation: all pectolytic enzyme activities in the 17 preparations analysed in this study were significantly different. The presence of ethanol reduced the enzymatic activity, apart from that of endopolymethylgalacturonase, and, in general, an increase of enzyme concentration raised the pectolytic enzyme activity. Received: 17 March 1997 / Revised version: 11 June 1997     

Evaluation of pectolytic activities of enological interest in industrial enzyme preparations

 The purpose of this research was to determine the activity of several pectolytic enzymes, such as pectin methyl esterase, endopolymethylgalacturonase, endopolygalacturonase, exopolymethylgalacturonase, endopolygalacturonase, pectin transeliminase and pectic acid transeliminase, from within preparations that are available on the Portuguese market. The selected preparations were as follows: 15 pectolytic enzyme preparations, one hemicellulolytic preparation and one glucanase preparation. The measurements of enzyme activity were carried out using model solutions with 50 mg·l^–1 SO₂, pH 3.2, 25°C, with and without 12% ethanol (v/v), and a 24-h incubation period. Quantitatively, the results proved to be heterogeneous, significantly varying from preparation to preparation: all pectolytic enzyme activities in the 17 preparations analysed in this study were significantly different. The presence of ethanol reduced the enzymatic activity, apart from that of endopolymethylgalacturonase, and, in general, an increase of enzyme concentration raised the pectolytic enzyme activity. Received: 17 March 1997 / Revised version: 11 June 1997     

Degradation of polysaccharides by immobilized depolymerizing enzymes

Polysaccharides in fruit and vegetable juices can be efficiently degraded using co-immobilized amylolytic and pectolytic enzymes combined with naringinase. The enzymes were immobilized on silica carriers for use in fining procedures to remove cloudiness.     

Cloning, sequence analysis and overexpression of a Saccharomyces cerevisiae endopolygalacturonase-encoding gene (PGL1)

Only a few yeast strains produce pectin-degrading enzymes such as pectin esterases and depolymerases (hydrolases and lyases). Strain SCPP is the only known Saccharomyces strain to produce these pectinases. One of these pectolytic enzymes. PGL1-encoded endopolygalacturonase (EC 3.2.1.15), hydrolyses the alpha-1,4-glycosidic bonds within the rhamnogalacturonan chains in pectic substances. This paper presents the cloning and sequencing of the first S. cerevisiae gene involved in pectin degradation. Few differences were found between the two deduced amino acid sequences encoded by PGL1-1 from a pectolytic (PG+) strain (SCPP) and PGL1-2 from a non-pectolytic (PG-) strain (X2180-1B). Similarities were found with other polygalacturonases from plants and other microorganisms. Of the two S. cerevisiae genes, only the one isolated from strain SCPP was able, by overexpression, to confer endopolygalacturonase activity to a laboratory strain of S. cerevisiae. Overexpression of PGL1-1 gene in a non-pectolytic strain resulted in halo formation on polygalacturonic acid-containing agar plates stained with ruthenium red.     

A study on the effects of sample pre-treatment on the amount of sesquiterpene lactones found in chicory (Cichorium Intybus L.) by ELISA and by HPLC

 The effects of sample preparation on the amount of some sesquiterpene lactones, i.e. bitter compounds, extracted from chicory (Cichorium intybus L.) have been studied. Sample preparation was performed using water or a citric acid solution both with and without cellulolytic and pectolytic enzymes. The concentrations of sesquiterpene lactones in the samples were measured by enzyme-linked immunosorbent assay (ELISA) and by high-performance liquid chromatography (HPLC). The greatest amounts of sesquiterpene lactones were obtained by treatment of the chicory samples in water in the presence of the enzymes. Evidence was obtained that both free and glucosylated sesquiterpene lactones are measured in the specific ELISAs. Received: 28 February 1996/Revised version: 10 June 1996