柑橘皮中果胶酯酶的生物学特性研究

研究了柑橘皮中的果胶酯酶的生物学特性。用盐析法从新鲜柑橘皮中提取果胶酯酶粗酶液,用pH-stat法测定果胶酯酶的活力。结果表明,该柑橘皮中的果胶酯酶的最适温度在50℃左右,且对热稳定性好,其最适pH在8左右。     

果胶及果胶分解酶对果蔬组织软化的影响

果胶分高酯、低酯果胶两种。高酯果胶上要用于果酱 果冻、凝胶软糖果馅芯及乳酸菌饮料等的稳定剂。低酯果胶主要用于冷冻甜点 色拉调味酱,冰淇淋、酸奶等的稳定剂。果胶与果汁生产时,果汁的粘度、清浊度有关。果蔬成熟时和热加工时组织的软化,与果胶的可溶性变化密切相关。引起果蔬中果胶分解溶化的主要酶是果胶酯酶(以下简称PE)和聚半乳糖醛酸酶(以下简称PG)。     

果胶酶在葡萄酒酿造中的作用及其实践应用

果胶酶是现代葡萄酒酿造中的重要辅料,大多数是由黑曲酶（Aspergillus niger）经特殊工艺制成的液体果胶酶或固体果胶酶。葡萄酿酒中常用的果胶酶通常是复合果胶酶,含有果胶裂解酶（Pectinlyase,PL）,果胶酯酶（Pectin esterase,PE）和聚半乳糖醛酸酯酶（Polygalacturonases,PG）等。     

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。     

两个品种桃蒸馏酒中甲醇含量差异性研究

为探究两个品种的桃蒸馏酒中甲醇含量的差异性,分别取不同采摘时期的两个桃子品种进行蒸馏酒的制作,采用气相色谱（GC）法测定桃蒸馏酒中的甲醇含量;并测定了两个品种桃果实的基本理化指标、多聚半乳糖醛酸酶（PG）活性、果胶酯酶（PE）活性及果实中的果胶含量;分别分析了甲醇含量与PG活性、PE活性及果实中果胶含量的相关性情况;并采用模拟发酵试验的方法进一步探究果胶含量及果胶酶含量对甲醇含量的影响。结果表明,两个品种桃蒸馏酒中甲醇含量差异大的原因主要与果实的PG活性、PE活性及果实中的可溶性果胶含量和原果胶含量显著相关（P＜0.01）,与果胶总含量无显著相关性（P＞0.05）;且模拟发酵试验证明了果胶含量和果胶酶活性是甲醇产生的重要途径之一。     

基于自由基介导的酚酸-柑橘果胶接枝共聚物制备及其理化特性

以柑橘果胶为研究对象，采用自由基介导的接枝方法制备酚酸-柑橘果胶接枝共聚物，并对接枝共聚物的结构和理化特性进行比较分析。结果表明：5 种酚酸-柑橘果胶接枝共聚物中接枝度最高的是丁香酸-柑橘果胶（74.2±1.38）mg/g，其次为龙胆酸-柑橘果胶（67.24±1.55）mg/g。与原果胶相比，接枝共聚物的分子质量分布向均一性转变并显著下降；龙胆酸-柑橘果胶、丁香酸-柑橘果胶接枝共聚物分子质量分别由（109.98±0.05）kDa下降至（65.11±0.02）kDa和（39.83±0.05）kDa；其酯化度由（51.62±1.46）%分别增加到（70.83±1.64）%和（72.73±2.18）%；半乳糖醛酸质量分数由（39.18±1.08）%分别增加到（52.42±1.36）%和（53.88±1.19）%；溶解度由（39.34±1.08）%分别增加到（54.40±1.36）%和（59.87±1.21）%。此外，通过傅里叶变换红外光谱和扫描电子显微镜等研究发现，酚酸-柑橘果胶接枝共聚物的单糖类型未改变，酚酸主要共价接枝于柑橘果胶链上，导致其热稳定性降低，并且由粗糙而致密的块状结构变成为表面相对光滑的片状结构。     

气调包装对草莓货架期延长保鲜内在品质的影响

植物组织或器官在衰老过程中常伴随细胞膜结构的破坏,导致组织结构和细胞区域化的丧失。研究经过气调包装(MAP)处理后草莓超微结构的变化,结果表明经过MAP处理能较好地维持草莓细胞形状。果胶酯酶(PE)活性是影响草莓货架期的内在因素之一。采用NaCl盐析法得到了草莓果胶酯酶粗提液,对草莓果胶酯酶的特性进行了探索。试验结果表明,氯化钙溶液对果胶酯酶的活性影响很大,植酸同样可抑制果胶酯酶的活性,以0.05%效果最好。     

柑橘酒酿造工艺研究

研究了柑橘酒发酵过程中甲醇含量的变化及其影响因素。结果表明,柑橘汁中添加果胶后发酵得到的柑橘酒甲醇含量更高;添加果胶的柑橘果汁中添加一定量果胶酶或蔗糖,甲醇含量也有所增加;添加金属离子,甲醇含量减少。正交试验结果表明果胶酶、CaCl2、蔗糖的含量分别为40mg/L、1.1g/L、180g/L时,柑橘酒中甲醇含量由150.48mg/L降低到15mg/L。     

试验温度对鲜橙汁果胶酯酶活性的影响

柑桔加工者都非常关心保持柑桔汁的混浊态。混浊态的丧失主要是由于果胶酯酶(PE)使果胶脱脂,产生果胶酸,后者与钙结合,形成不溶于水的果胶酸钙。据报道,钝化柑桔PE需90℃持续15秒以上的热处理。商品生产中,钝化PE是在蒸发器中浓缩柑桔汁期间完成的。但是,加热和抽真空导致了挥发性香味物质的损失。采用冷冻浓缩或反渗透浓缩,能在     

柑橘类果汁加工副产品综合利用研究进展

综述了柑橘类果汁加工主要副产品(包括香精油、柑橘果胶、桔皮色素、膳食纤维、黄酮类化合物和类柠檬苦素)的功能特性，以及国内外对这些副产品的综合开发利用情况。并对我国柑橘副产品的加工利用提出建议。     

高压脉冲电场杀菌技术在橙汁中的应用

食品冷杀菌技术是一类不用热能杀死微生物,不影响食品营养、质构、色泽和风味的新兴杀菌技术。主要阐述了高压脉冲电场杀菌（PEF）的基本原理和优点,讨论了其在橙汁中的应用,并对比了PEF处理和热处理（90℃,15s）对橙汁微生物的杀灭效果及橙汁理化指标的变化。     

现代分离技术与装备在橙汁加工中的应用

现代科技的发展以及人类社会对食品安全、营养与健康要求的提升,推动了果蔬汁加工技术由传统型向现代产业型转变的进程。现代的果蔬汁加工除应用流体与流体输送、热力学（传导与热交换）、生物学（酶制剂）、制冷技术等工程原理之外,已经扩展到高效榨汁、固液分离、蒸发浓缩、蒸馏与精馏、萃取、吸附与离子交换、膜分离等物理分离技术与装备的应用方面。在橙汁加工中,不仅要求去除对橙汁风味、品质构成不利影响的橙皮精油、橙皮苷物质,同时还要求最大限度减少热敏物质及维生素C等成分的损失。讨论了采用物理分离技术与装备同其他作业单元的完美组合,限制对橙汁品质构成不利影响物质的引入,降低营养成分的损失,使得橙汁获得色、香、味俱佳品质的方法;并对备受关注的橙汁加工副产品橙皮渣废弃物转化为新资源进行综合利用,提升新的经济增长点提出了建议。     

Low pH Inactivation of Pectinesterase in Single Strength Orange Juice

Frozen orange juice concentrate (63.8° Brix) was reconstituted with water to single strength juice and supplemented with a commercial citrus pectinesterase (PE) to give an activity of 1.5 PE units/mL juice. Reconstituted juice and freshly squeezed single strength orange juice were treated with a cation exchange resin. Resin treatment decreased the pH of the juice from 3.75 to 2.0 and completely inactivated PE. PE was also inactivated following acidification of the juice to pH 2.0 with concentrated hydrochloric acid. Very little cloud loss occurred in refrigerated (4°C) juice at pH 2.0 for approximately 12 wk; however, a loss (> 95%) of ascorbic acid resulted. Only microorganisms died-off rapidly (> 99.9%) in juices adjusted to pH 2.0 using ion exchange resin, but not in juices lowered to pH 2.0 with HCl.     

Influence of Pectinesterase Inhibitor from Jelly Fig (Ficus awkeotsang Makino) Achenes on Pectinesterases and Cloud Loss of Fruit Juices

ABSTRACT: Citrus and jelly fig achene pectinesterase (PE) (1 U/mL) activity was remarkably inhibited by PE inhibitor (PEI) (2 mg/mL) from jelly fig ( Ficus awkeotsang Makino) achenes, in the absence or presence of 0- to 500-mM salts or 0 to 30% of sugars. Changes in temperature (20 to 40 °C) apparently decreased the activity of citrus PE in PE-PEI reaction mixture. Enzyme-activity curves for jelly fig PE alone and for that in combination with PEI were parallel. Activity of crude PEs (1 U/mL) from tomato, apple, asparagus, and guava was reduced remarkably. Cloud loss of fresh tomato juice, apple juice, and papaya juice was greatly inhibited by PEI (1 mg/mL) during 12-wk storage.     

鲜牛乳橙汁复合饮料研发的响应面设计优化

以夏橙果汁和鲜牛乳为主要原料,采用Design-Expert7.0软件,通过单因素试验和Box-Behnken的中心组合试验设计以及响应面分析,对复合稳定剂配比以及鲜牛乳橙汁复合饮料原料配比进行优化研究。结果表明：复合稳定剂配比为：CMC-Na0.23%、海藻酸钠0.15%、果胶0.07%,此时复合饮料的离心率为2.86%,稳定性较优;原料配比为：鲜牛乳24.76%、橙汁21.06%、白砂糖5.22%、柠檬酸0.10%,在此配比方案下鲜牛乳橙汁复合饮料感官评分值为86.63分,可制作出质量和风味俱佳的鲜牛乳橙汁复合饮料。     

雪莲果防褐变技术的研究

从雪莲果块茎中提取多酚氧化酶(Polyphenol Oxidase,PPO),采用分光光度法对其最大吸收波长最适反应温度进行研究,还研究了VC、氯化钠、柠檬酸、柠檬汁、橘子汁对雪莲果PPO活性的影响。结果表明:雪莲果多酚氧化酶最大吸收波长为400nm,最佳反应温度为30℃。氯化钠、抗坏血酸、柠檬酸、柠檬汁、橘子汁都有抑制褐变的效果。组合抑制剂抑制褐变效果比单一抑制剂好且最佳组合抑制剂为1.5%氯化钠+0.5%抗坏血酸+1.5%柠檬酸+10%柠檬汁。     

Determination of phthalate ester congeners and mixtures by LC/ESI-MS in sediments and biota of an urbanized marine inlet

Phthalate esters (PEs) are a group of widely used commercial chemicals consisting of many different congeners. Concentrations of di(2-ethylhexyl) phthalate ester in the parts per million range have been observed in sediments from locations in North America and Europe. However, sediment and biota concentrations of other widely used PEs (i.e., dibutyl phthalate, diisononyl phthalate, and diisodecyl phthalate) are rare and often in doubt because of analytical difficulties. One of the problems is that commercial formulations predominantly consist of PEs with a specific molecular weight but include many isomers within each molecular weight class. Currently there are no analytical methods or required standards to fully separate PEs into the different molecular weight classes corresponding to the formulations from which they originate. Hence, ambient total and mixture-specific PE concentrations do not exist. This study presents a new method based on reversed-phase liquid chromatography/ electrospray ionization mass spectrometry (LC/ESI-MS) for the quantitative determination of individual PEs, including six congeners on the U.S. EPA Priority pollutant list and several commercial PE isomeric mixtures, in complex environmental matrixes. The method is applied to determine the composition of PE concentrations in sediments and fish in an urbanized marine ecosystem. PE fingerprints in sediments show a predominance of high molecular weight PEs and match per capita consumption levels of PEs. Fingerprints in fish tissue show a predominance of low molecular weight PEs and do not match per capita consumption levels. The findings indicate that the higher molecular weight PEs are less biologically available than the lower molecular weight ones.     

桔子果酒的发酵工艺优化

以四川桔为原料,对桔子果酒发酵工艺参数进行优化。比较两株果酒酵母的发酵性能,单因素试验基础上对发酵初始糖度、发酵温度、初始pH值和酵母菌接种量进行L9（34）正交试验。发酵性能结果表明果酒酵母菌株1为最佳发酵菌株,影响桔子果酒感官品质的各因素主次顺序为发酵温度〉酵母接种量〉初始糖度〉初始pH,结合酒精度和感官综合评分控制主发酵温度为21℃、酵母接种量为6%、初始糖度为20%和初始pH 3.4的条件下选用果酒酵母1发酵新鲜桔子全汁,可以获得口感、香气适宜的桔子果酒。     

Quality Parameters of Packaged Refrigerated Apple Cubes in Orange Juice

The quality of apple cubes (Red Delicious and Granny Smith) maintained in pasteurised or fresh orange juice with sucrose and chemical preservatives: acidulants (citric and ascorbic acids) and potassium sorbate or sodium benzoate, packaged in plastic films of different gaseous permeability (polyethylene (PE) and EVA-SARAN-EVA (ESE)), was analysed during storage at 10 °C. Surface colour, microbial growth and instrumental texture changes were measured. Microbial flora was identified, and its growth was mathematically modelled. Shelf-life values of 10d in polyethylene and higher than 25d in ESE film, maintaining acceptable quality attributes, were obtained for both apple varieties in pasteurised juices. For Red Delicious in unpasteurised orange juice with acidulants and potassium sorbate (0.125-0.250 g/kg), shelf-life values were 7.5-8.5d in PE and higher than 15 d in ESE film. For Granny Smith apples in unpasteurised juice without potassium sorbate, shelf-life values were 10 d in PE and higher than 15 d in ESE. Higher concentrations (0.375-0.50 g/kg) of potassium sorbate adversely affected colour. Sodium benzoate was discarded as preservative because it produced severe browning in both apple varieties. All the samples showed safe sanitary conditions; coliforms microorganisms did not grow in any of the tested conditions.     

USE OF AN ELECTRONIC NOSE TO STUDY THE CONTRIBUTION OF VOLATILES TO ORANGE JUICE FLAVOR

Ideal orange juice and orange juice from which the volatile compounds had been stripped were analyzed using an electronic nose. In the ideal juice, dlimonene was the volatile in highest concentration. The stripped orange juice contained less than 1% of the original d‐limonene and all other volatiles were reduced to below levels of detection as measured by gas‐chromatography analysis. The electronic nose was able to distinguish between the two orange juices, ideal and volatile stripped. Four commercial orange juice essences were added to the stripped orange juice at concentrations up to 2%. The differences, as measured by the electronic nose, between the original orange juice and the volatile stripped orange juice were reduced when orange essence was added to the volatile stripped juice. In orange juice flavor, α‐pinene, sabinene, β‐myrcene, and d‐limonene appear to play an important role.