果蔬加工中果胶甲基酯酶活性抑制的研究进展

果胶甲基酯酶（pectin methylesterase,PME）是一种广泛存在于高等植物、真菌和细菌的果胶降解酶,其残余活性会导致果蔬汁和鲜切果蔬等产品产生分层沉淀、析水结块、质构软化等品质劣变。因此,在果蔬加工过程中实现对PME活性的有效抑制是加工的重要目的。目前生产中对于PME活性的抑制主要以热加工方式为主,但这会对热敏性果蔬产品品质造成不可逆转的不良影响。随着人们生活水平和健康意识的提高,为了满足人们对更高品质产品的追求,一些新型热加工和非热加工技术以及PME抑制剂逐渐被研究并应用于PME活性的抑制。本文综述当前热、非热加工方式和抑制剂对于PME的抑制效果及其机理,并列举不同加工方式联合处理或加工手段与抑制剂联合处理在PME抑制方面的应用情况,以期为未来更高品质果蔬产品的加工提供理论指导。     

果胶甲酯酶的作用机理及在食品加工中的应用

该文综述食品加工中应用较为广泛的果胶酶的一个分类——果胶甲酯酶的作用机理及目前在果蔬汁澄清、果蔬制品改善、低酯果胶制备等食品相关行业中的应用现状,并进行总结,为果胶甲酯酶在食品加工中的深入研究开发及未来应用前景预测提供参考。     

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。     

柑桔属柠檬类果实果胶酯酶的活性分析

果胶酯酶（PE或PME）能催化果胶脱酯生成低酯果胶和果胶酸,属于一类果胶酶,广泛应用于食品特别是果品加工工业中。以新鲜柠檬为原料,采用NaCl-冷冻离心-盐析的方法提取柠檬果实中的果胶酯酶,pH-stat法对果胶酯酶进行活性分析。研究温度、pH、相对储藏度等因素对柠檬类果实果胶酯酶的活性影响,并探索该酶的最适温度、最适pH值,进而研究该酶的热稳定性;对柠檬果实中果胶含量进行测定。实验表明：58℃,pH=6.90时柠檬中的果胶酯酶的活力最高。     

酶制剂在果蔬汁澄清及加工中的应用研究进展

当前我国果蔬汁工业迅猛发展,因酶制剂可解决果蔬汁加工中出汁率低、澄清难、易褐变、风味物质易流失和苦味物质难去除等问题,在该领域中得到广泛的应用。目前在果蔬汁加工中应用的酶制剂主要有果胶酶、纤维素酶、淀粉酶、葡萄糖氧化酶、柚苷酶等。本文介绍了果胶酶、纤维素酶、淀粉酶等常见酶制剂在提高果蔬出汁率方面的作用机制及应用进展,比较了酶制剂与其他方法对果蔬汁澄清效果的差异,陈述了葡萄糖氧化酶、柚苷酶、β-葡萄糖苷酶等在改善果蔬汁感官品质方面的应用现状。在分析酶制剂在果蔬汁加工中存在问题的基础上,对酶制剂的应用前景和发展方向进行了展望,为酶制剂在果蔬汁行业的应用提供进一步的依据和参考。     

酶制剂在果蔬汁加工中的应用

酶制剂可以解决果蔬汁加工中存在的出汁率低、澄清难、风味难保持等问题。介绍果胶酶和纤维素酶等常见酶制剂在提高果蔬出汁率、澄清及改善感官方面的应用进展,对扩展酶制剂的发展方向和前景进行展望。     

提高向日葵低酯果胶质量的方法

果胶是一种食品添加剂,可做增稠剂、增粘剂,在食品加工部门作为组织构成物质被广泛使用。用向日葵低酯果胶还可以制取适合儿童。老人、肥胖病人和糖尿病人食用的低糖度低热量果酱、果冻食品。低酯果胶具有对铅、铜、锡、     

果胶基复合包装在果蔬保鲜中的应用

果胶是一种广泛存在于植物细胞壁中的天然高分子材料,因具有生物相容性、易修饰和改性、可降解等优点被逐渐应用于果蔬保鲜中。果胶基复合包装因其包装性能更佳、保鲜效果更好而打破了单一果胶包装在果蔬保鲜中的局限逐渐成为果蔬的主要包装方式。本文介绍了果胶的结构及成膜特性,从塑化剂、天然聚合物、生物活性物质和纳米材料四个方面阐述了果胶基复合包装制备的主要成分,并对果胶基复合薄膜和涂膜两种方式在果蔬保鲜中的应用进行了综述并提出了展望,以期为今后食品的保鲜贮藏和新型包装材料的发展提供技术借鉴。     

果胶酶在食品工业中应用的研究进展

果胶酶是一类分解果胶物质的酶的总称,其在自然界中分布很广。该文综述了果胶酶的特性及其在果汁澄清、提高果蔬汁的出汁率、提取生物活性功能成分以及改善酒的品质等食品领域中的应用,并提出了目前存在的问题及以后的研究发展方向。     

超高压与重组果胶甲酯酶抑制剂联合应用对鲜榨橙汁果胶甲酯酶活性及品质的影响

为了探究超高压与重组果胶甲酯酶抑制剂(recombinant pectin methylesterase inhibitor,rPMEI)联合处理对鲜榨橙汁中果胶甲酯酶(pectin methylesterase,PME)活性及品质的影响,研究了超高压(400、500和600 MPa,5 min,20 ℃)与重组果胶甲酯酶抑制剂对橙汁微生物、PME酶活、色泽和V_C含量的影响。结果表明:超高压处理条件为500 MPa/5 min,rPMEI添加浓度为0.06 mg/mL时,橙汁中的菌落总数、霉菌与酵母菌数均能达到农业行业标准《NY/T 434-2016绿色食品、果蔬汁饮料》所规定的要求,同时PME被完全钝化;橙汁色泽变化显著小于热处理组(ΔE*=1.22<2.26);V_C保留率为85.1%,显著高于热处理组(保留率=8.33%)。     

Pectins in Processed Fruit and Vegetables: Part I—Stability and Catalytic Activity of Pectinases

ABSTRACT: Pectinases catalyze numerous pectin conversion reactions strongly impacting on the quality of fruits, vegetables, and the related intermediate and end products. The effect of processing on the stability and catalytic activity of pectinases is of prime importance to food processors since desirable and/or deleterious reactions can be tailored (accelerated or inhibited) meeting specific quality targets. Of the multiple endogenous enzymes involved in the modification and degradation of pectin, pectinmethylesterase (PME), and polygalacturonase (PG) have been widely investigated in the context of fruit and vegetable processing. This review covers the stability and catalytic activity of endogenous plant PME and PG including the quantitative approaches applied in inactivating and/or boosting the catalytic activity of the enzymes in purified and real food systems. This will be discussed in the context of both traditional and novel food processing technologies.     

Tomato Product Quality from Transgenic Fruits with Reduced Pectin Methylesterase

Juice from transgenic tomato (Lycopersicon esculentum cv Rutgers) fruits with reduced levels of pectin methylesterase (PME) activity due to the expression of a PME antisense gene exhibited improvement in quality. The percentage increase in juice from transgenic fruits over that of juice from wild type Rutgers ranged between 5.1–5.3 for total solids, 3.8–6.1 for soluble solids, 70–80 for efflux viscosity, 180–220 for serum viscosity and about 50 for precipitate weight ratio. Time of harvest had no effect on quality of juice. Ketchup prepared from transgenic fruit juice had a lower Bostwick value, reduced serum separation and high serum viscosity compared to ketchup from parental Rutgers.     

Kinetics of Tomato Pectin Methylesterase Inactivation by Temperature and High Pressure

ABSTRACT: In this study we investigated the inactivation of endogenous pectin methylesterase (PME) in tomato juice during combined high-hydrostatic pressure (ambient to 800 MPa) and moderate temperature (60 to 75 °C) treatments under isobaric and isothermal processing conditions. PME inactivation rates increased with increasing processing temperature, with the highest rate obtained during processing at 75 °C and ambient pressure. Inactivation rates were dramatically reduced as soon as processing pressure was raised. High inactivation rates were again attained when processing pressure exceeded a value of about 700 MPa. Such a behavior was described by considering two parallel mechanisms of inactivation, each one following first order kinetics with its own kinetic parameters.     

In vitro oral processing of raw tomato: Novel insights into the role of endogenous fruit enzymes

During consumption of fruits, the breakdown of the fruit tissue due to oral processing (chewing, mixing with saliva) may activate or increase the rate of endogenous enzyme activities via the disruption of the cell wall, cellular decompartmentalization, and particle size reduction allowing the enzymes to reach their substrates. The aim of this study was to investigate the activity of one such endogenous fruit enzyme (pectin methylesterase [PME] [E.C. 3.1.1.11]) during in vitro oral processing of raw tomatoes and associated changes in viscosity and microstructure. Oral processing of tomatoes purees was examined in the presence of artificial saliva (AS) at 37°C. in vitro oral processing was followed using immunofluorescence microscopy, apparent viscosity measurements, spectrophotometric, and titrimetric techniques. The results demonstrated that PME had slight but significant activity in the tomato fruit during in vitro oral processing generating methanol as a function of oral processing time, which was further evidenced using immunolabeling techniques to detect methylated pectin epitopes. A significant shear‐thinning behavior of the tomato puree was observed due to dilution and/or endogenous fruit enzyme activity. These results suggest that activity of other fruit enzymes, such as polygalacturonase, which catalyzed the depolymerization of unmethylated pectin chains, might have resulted in a decrease in viscosity, which compensated for the increased potential for gel formation (if any) caused by PME. These interesting insights into the role of endogenous fruit enzymes might pave the way to the understanding of fruit viscosity modification occurring in the mouth and help in rational design of new fruit‐based products.     

Pectins in Processed Fruits and Vegetables: Part III—Texture Engineering

ABSTRACT: Current interest in controlling the textural and rheological properties of processed fruit and vegetable products has stimulated research on the biochemistry of the cell wall, with particular reference to pectin and its degradation. This review covers the literature over the last decade with respect to pectin engineering in the field of fruit and vegetable processing. Several applications, illustrating that refined manipulation of chemical and/or enzymatic pectin degradation can be used as a tool to improve the texture/rheology of thermally processed and frozen fruit and vegetable products, are described. The discussion includes an evaluation of the role of novel technologies such as high‐pressure processing in pectin engineering of processed fruits and vegetables. Furthermore, the possible role of pectin‐related enzymes other than pectin methylesterase (PME) and polygalacturonase (PG) and of the nontraditional, ferulic acid‐mediated cross‐linking process is discussed. Finally, new trends, challenges, and suggestions for future pectin engineering research are covered in this review.     

Reassessment of Some Fruit and Vegetable Pectin Levels

Several reviews of pectin as a soluble fiber have included unreliable tables of pectin content for fruits and vegetables. Values given for ranges of pectin content in the fresh, edible portion are actually presented in original reports variously as peel pectin content, dry weight values, soluble rather than total pectins, and some values have been for unripe fruit. This has resulted in reporting pectin levels for some products that may be 2-10 times higher than other published data on the same product. This report examines the original sources and errors of such data and, when available, provides other more substantiated published values.     

非热加工技术对果蔬类胡萝卜素生物利用度的影响研究进展

类胡萝卜素是一类广泛存在于果蔬食品中的脂溶性天然色素,具有多种生理功能.通常果蔬中类胡萝卜素的生物利用度较低,不同加工方式对类胡萝素的释放和生物利用度会有不同的影响,通过科学的手段提高果蔬中类胡萝卜素的生物利用度成为果蔬加工领域研究的热点.本文简述了不同非热加工技术(高压均质技术,超高压技术,超声波技术,高压脉冲电场技...     

喷雾干燥条件对果蔬粉加工特性影响研究进展

果蔬粉加工是果蔬综合利用的重要方法之一。果蔬因富含糖类和热敏性成分,普通干燥无法制备性能优良的果蔬粉产品。喷雾干燥因效率高,出风温度低,产品性能好,是目前果蔬粉常用方法。喷雾干燥中,不同干燥条件对果蔬粉产率、品质有着重要影响。该文综述进风温度、助干剂种类和添加量、进料浓度、进料流量、热空气流量对果蔬粉产率和品质的影响,分析果蔬粉产率、性质变化的原因,以期为喷雾干燥法制备果蔬粉提供参考。