柚皮苷酶脱苦工艺优化及对金桔汁品质的影响

为优化柚皮苷酶对金桔汁的脱苦工艺,试验采用单因素试验,考察了酶用量、pH、酶解温度和酶解时间对柚皮苷酶脱苦效果的影响。在此基础上采用响应面分析优化柚皮苷酶脱苦工艺条件,并通过VC、可溶性固形物、氨基酸等营养成分保留率,评价脱苦方法对金桔汁品质的影响。响应面法分析显示,各因素对脱苦率的影响均达到显著水平,但因素间的交互作用未达到显著水平,经优化的柚皮苷酶脱苦的最优工艺参数为:酶添加量0.6g/L, pH 4.2,酶解温度51℃,酶解时间93 min。在此条件下,脱苦率为81.74%。柚皮苷酶脱苦法处理30 d后的金桔汁,其VC含量下降25.9%,总氨基酸含量下降10.2%,可溶性固形物和总酸含量下降5%和3%。柚皮苷酶脱苦法对金桔汁营养成分影响较小。柚皮苷酶对金桔汁脱苦率影响高,对营养品质影响小,操作简单,是一种行之有效的脱苦方法。     

柚皮苷酶对琯溪蜜柚果汁脱苦效果工艺优化

以琯溪蜜柚果汁为对象,研究在不同条件下柚皮苷酶对蜜柚果汁的脱苦效果。采用HPLC 测定柚皮苷含量,通过单因素试验分别考察加酶量、温度、酶解时间及pH 值对柚皮苷酶酶解反应的影响,在单因素试验基础上以柚皮苷脱除率为指标进行正交试验,确定最佳工艺条件：酶解温度60℃,酶活7.4U/mL 柚汁,酶解时间100min,pH3.6。在此条件下琯溪蜜柚果汁的柚皮苷脱除率达97% 以上。     

5种柚汁中主要抗氧化成分含量及其抗氧化能力的比较

采用高效液相色谱法测定了5种柚汁中黄酮类物质、VC的含量.并用FRAP、DPPH及ABTS三种方法对其抗氧化能力做出评价.通过比较,得出佛柚汁中的柚皮苷含量、VC含量和总酚含量均为最高;除胡柚汁外,其他柚汁均未检测到橙皮苷和新橙皮苷;佛柚汁的抗氧化能力最强.酚类物质和VC则是柚汁中最主要的抗氧化物质.     

胡柚皮中柚皮苷的超声提取工艺研究

柚皮苷为芸香科柑橘属植物次生代谢产物,不仅具有较高的营养价值,而且具有极高的药用价值而成为食品和医学领域研究的热点问题.为建立柚皮中柚皮苷的提取工艺,本试验通过单因素试验考察了溶剂类型、溶剂体积分数、料液比、提取时间及提取功率5个因素对胡柚中柚皮苷提取率的影响,并在此基础上用正交试验进行工艺参数的优化.实验结果表明,从胡柚皮中提取柚皮苷的较佳条件为:用65%的甲醇溶液作溶剂,料液比1:20,提取时间40min,提取功率28W,在试验所得优化工艺条件下柚皮苷提取率为1.9%.对胡柚皮中的主要有效成分柚皮苷进行提取研究,不仅可使柚皮这一废弃物得到合理而有效的利用,也为柚皮苷的深度开发利用提供参考依据,具有重要的理论意义和实际应用价值.     

热处理与胡柚汁中柠檬苦素变化的相关性分析

采用高效液相色谱法进行定量分析,研究热处理温度及时间对胡柚汁中柠檬苦素含量的影响。结果表明:在热处理时间一定时,随着处理温度的升高,胡柚汁中柠檬苦素的含量呈较稳定上升趋势,但85～90℃时含量基本不变,90℃后又转而增加;在热处理温度一定时,随着处理时间的延长,柠檬苦素含量总体上升但增加速率逐渐变小,总含量趋于稳定。两因素四水平完全试验结果显示,处理时间是影响胡柚汁热加工中柠檬苦素含量变化的主要因素,加热温度次之;在较高处理温度(85～95℃)时,随着加热时间的延长,各个处理温度下柠檬苦素的含量有逐渐达到一个集中区域的趋势。     

超高压和热处理对胡柚汁理化品质的影响

研究了高压(200～600 MPa)、20～60℃处理15 min和热处理(90℃处理2 min及80℃处理30 min)对胡柚汁理化品质的影响.试验结果表明:经超高压和热处理后胡柚汁的平均粒径增大,而超高压处理对胡柚汁色泽的影响较小,对pH值和可溶性固形物含量无显著影响.经超高压处理的胡柚汁的L-抗坏血酸保留率在91.97%～98.29%之间,其中以200MPa压力下处理的保留率较高.超高压和热处理后胡柚汁的柚皮苷和新橙皮苷含量略有降低,果汁的抗氧化性略有提高.     

胡柚中3种主要黄酮类物质的含量测定

目的：建立常山胡柚3种主要黄酮类物质含量的测定方法,并比较常山胡柚中皮、肉、籽中该3种黄酮类物质含量的差异。方法：采用反相高效液相色谱法分离检测胡柚中柚皮苷、橙皮苷、新橙皮苷的含量;流动相为乙腈-水(23:77,V/V),柱温25℃,流速1.0mL/min,检测波长283nm。结果：柚皮苷在3.22～1030μg/mL、橙皮苷在0.59～380μg/mL、新橙皮苷在0.077～990μg/mL范围内,黄酮类物质的质量浓度与峰面积呈良好的线性关系;柚皮苷、橙皮苷、新橙皮苷的平均回收率分别为98.43%(RSD＝4.07%)、98.70%(RSD＝4.30%)、99.90%(RSD＝3.47%);并以柚皮苷、橙皮苷和新橙皮苷为标准比较胡柚副产物皮、籽与胡柚肉含量的差异,初步得出皮＞肉＞籽。结论：该方法简便、准确、可靠、重复性好,可用于常山胡柚的质量控制。     

琯溪蜜柚幼果中柚皮苷含量变化规律

为探明琯溪蜜柚幼果作为柚皮苷提取原料的最优时期,利用高效液相色谱分析研究种植地海拔、果实发育期、果实部位、贮藏时间及加热干燥对琯溪蜜柚幼果中柚皮苷含量的影响。结果表明：高海拔地区（668 m）种植的琯溪蜜柚幼果中柚皮苷含量高于低海拔地区（40 m）种植;随着发育期的增长,果实内部白囊与绿色表皮柚皮苷含量均呈下降趋势;同一时期采摘的幼果经贮藏由绿变黄的过程中柚皮苷含量不断升高;加热干燥处理会显著降低新鲜幼果柚皮苷含量。高海拔地区（668 m）种植的I期琯溪蜜柚幼果,经过贮藏完全变黄后柚皮苷含量最高,表皮和白囊柚皮苷质量分数分别达28.3%和26.5%。研究结果为科学利用琯溪蜜柚幼果为原料制备柚皮苷提供了实验依据,具有重要的参考价值。     

黑曲霉DB056柚苷酶制剂对琯溪蜜柚果汁的脱苦效果

采用高效液相色谱法测定琯溪蜜柚果汁中柚皮苷及其降解产物的变化,研究黑曲霉DB056柚苷酶制剂脱苦琯溪蜜柚果汁的优化条件;并且在此优化条件下,使用该柚苷酶制剂对琯溪蜜柚鲜柚汁、浑浊浓缩柚汁和澄清浓缩柚汁进行脱苦。结果表明：黑曲霉DB056柚苷酶制剂催化琯溪蜜柚果汁中柚皮苷水解成普鲁宁和柚皮素;该柚苷酶制剂在40～55℃、果汁自然pH值条件下对琯溪蜜柚鲜柚汁进行脱苦,酶用量90U/mL、处理时间80min,柚皮苷脱除率达到89%;处理不同浓缩程度的浑浊浓缩柚汁,脱苦率约为80%左右。结果说明黑曲霉DB056柚苷酶制剂对琯溪蜜柚果汁具有良好的脱苦作用。     

几种柑橘类果汁中主要苦味物在加工过程中含量变化的研究

目的:研究榨汁温度、热处理、过滤等加工技术对几种柑橘类果汁主要苦味成分的影响, 为脱苦工艺提供试验依据.方法:采用高效液相色谱法检测3种柑橘类果汁中柚皮苷和柠檬苦素类化合物的含量, 比较不同的预处理方式、加热温度、加热时间对其含量的影响.结果:不同品种的柑橘果汁的主要苦味物质含量差别较大, 果实预冷至4℃后榨汁可减少苦味,果汁苦味物随热处理温度的升高而增加, 同时柚皮苷和柠檬苦素类化合物的含量分别在加热至20 min和15 min时达到最大值.结论:榨汁温度、热处理、过滤等加工技术对柑橘类水果的苦味物质含量具有重要的影响,控制适宜的工艺参数有利于减少果汁中苦味物质的含量.该研究对于柑橘果汁的脱苦工艺具有重要的参考价值.     

果胶酶澄清柚子汁工艺条件研究

通过单因素试验和正交试验,研究了果胶酶对柚子汁的澄清工艺.单因素试验结果表明,果胶酶用量为0.08～0.10 g/L,pH值为3.0～4.0,温度为25～35℃,酶解时间为1.5～2.5h条件下,果胶酶对柚子汁澄清处理的效果较好,果汁中的可溶性固形物含量基本不变.正交试验得到的果胶酶澄清柚子汁的最佳工艺条件为果胶酶用量0.09 g/L,最适pH值为3.5,酶解温度25℃,酶解时间1.5 h.     

Quality of canned grapefruit juice produced in Cuba during four seasons

Canned single-strength grapefruit juice samples were collected biweekly from the main producing plant in Cuba during the 1980–81 to 1983–84 seasons. They were analyzed for °Brix, acid, naringin and limonin content and evaluated for sensory quality. Average values for each quality factor vary from season to season. Better sensory quality was found in samples with high Brix/acid ratio and lower bitter compounds content. No correlation relationship was found between Brix, Brix/acid ratio, naringin and limonin. The first 3 are the main quality factors related to grapefruit juice flavour.     

Treatment of Grapefruit Juice for Bitterness Removal by Amberlite IR 120 and Amberlite IR 400 and Alginate Entrapped Naringinase Enzyme

ABSTRACT: Treatment of grapefruit ( Citrus aurantium ) juice with Amberlite IR 400 resulted in 69.23% naringin removal after 5 min exposure with significant clarification and 89.41% tartness (acidity) reduction. Amberlite IR 120 removed only 9% naringin in 1 min with increased shelf life of the juice without any change in clarity, quality, and naringin content. Alginate entrapped naringinase treatment of the juice resulted in 83.84% naringin hydrolysis at 55°C and 220 rpm in 180 min with 1.98 enzyme units/mL of juice. The soluble enzyme hydrolyzed only 65.53% naringin under similar conditions. Kinetic constant values of the immobilized and soluble enzymes were found to be 9.75 mM and 20 mM, respectively.     

Evaluation of the Properties of Polystyrene Divinylbenzene Adsorbents for Debittering Grapefruit Juice

Various physical properties of polystyrene divinylbenzene adsorbents involved in the removal of the bitter compounds naringin and limonin from grapefruit juice were investigated in a series of batch reaction processes. The removal of naringin from model systems and, naringin and limonin from grapefruit juice increased with the degree of cross-linkage and surface area of the adsorbents which had a solid density higher than 1.2 g/mL (dry) to ensure complete submersion. The specific surface area appeared to be the major factor in the debittering process. Regeneration with 95% ethanol was found to be more efficient than warm water. Sensory evaluation tests showed that more than 65% of the panelists preferred the less bitter treated juice over the control.     

Relationship Between Limonin Concentration and Naringin Concentration in Commercial Single Strength Grapefruit Juice

The limonin and naringin content of commercial single strength grapefruit juice (Citrus puradisi) samples was measured by immunoassay. Results obtained from a Linear Regression Analysis of Variance showed that there was no correlation between limonin and naringin concentration. Therefore, to determine the total bitterness potential of the product, each of these two compounds would have to be determined.     

Contribution of response surface methodology to the modeling of naringin hydrolysis by naringinase Ca-alginate beads under high pressure

Naringin is the dominant flavonoid bitter principle in grapefruit juice. The aim of this work was the modeling of the enzymatic hydrolysis of naringin, with naringinase immobilised in Ca-alginate beads, under high pressure, in order to optimize this technique for removal of the bitter taste from juices, using response surface methodology (RSM). A central composite rotatable design (CCRD) was employed involving two variables (pressure and temperature) at five levels (−√2, −1, 0, +1, +√2). The second-order polynomial equations with R² values above 0.9 showed good agreement between experimental and predicted, respectively, naringinase activity, naringin conversion and naringenin formation. The higher naringin conversion of 81% was obtained using 205 MPa and 60 °C, during a process time of 30 min.It was found that pressure and temperature, as well as their interactions, had significant effects (p < 0.001) on naringin hydrolysis in model solutions (acetate buffer pH 4.0). Validation experiments carried out under selected conditions showed good correspondence between experimental and predicted naringinase activity, naringin conversion and naringenin formation, in model solutions and in grapefruit juice.These are promising results to optimize this technique for the removal of the bitter taste and, after future microbial studies to be addressed, as a sterilisation/pasteurization process of citrus juices.     

柚苷酶高产菌株选育及其产酶在蜜橘果汁脱苦中的应用

为了得到1株高产柚苷酶菌株并探究其工业应用价值,从发霉的柚子皮上筛选出1株塔宾曲霉(Aspergillus tubingensis)MN589840,采用紫外与常压室温等离子体(atmospheric room temperature plasma,ARTP)复合诱变技术,获得突变株UA13,其柚苷酶活力可达41.524 U/mL,是原始菌株的3.06倍。对酶解条件进行探究,其酶解最适温度为40~50℃,最适pH值为5.0。利用突变株UA13发酵产酶脱苦宜昌蜜橘果汁并进行理化指标检测,当酶解约50 min时,果汁中柚皮苷含量低于柚皮苷苦阈值;当酶解时间>75 min,果汁中仅剩下少量柚皮苷。使用高效液相色谱对脱苦结果验证检测,结果显示,突变株UA13产酶可有效水解果汁中的柚皮苷,且能提高果汁风味。因此,突变株UA13具有潜在的工业应用价值,为后续实验研究奠定基础。     

Investigation of citrus flavor adsorption during debittering of grapefruit juice using kinetic modeling and response surface methodology

Reconstituted grapefruit juice was debittered with XAD-7HP adsorbent resin in batch experiments and the adsorption rate constants of the bitter principal naringin and the volatile flavor compounds α-pinene, β-myrcene, dlimonene, α-terpineol, and β-caryophyllene were determined using a pseudo-first order kinetic model. The highest rate constants were observed consistently for the off-flavor α-terpineol, followed by naringin and the other flavor compounds. The rate constant of each substance was influenced significantly by temperature, ratio of adsorbent/juice, and, except for α-terpineol, by the interaction of both factors (p<0.05). Response surface methodology (RSM) was applied for the development of regression models to predict the adsorption rate constants of all substances. On the basis of the regression models for d-limonene and naringin, a factor combination that minimized loss of flavor and maximized bitterness reduction during the debittering procedure was determined to be a combination of low temperature (13.9°C) and high adsorbent/juice ratio (3.6%).     

Reduction of Bitterness and Tartness in Grapefruit Juice with Florisil

Treatment of commercial grapefruit juice with Florisil (activated magnesium silicate) simultaneously reduced the content of citric acid and the bitter compounds limonin and naringin. Ascorbic acid concentration and °Brix (total soluble solids) were not altered by the Florisil treatment. Experienced taste panelists were able to differentiate between the nontreated and Florisil-treated juice on the basis of bitterness and tartness (acidity). The panelists indicated a preference for the Florisil-treated juice.