High-Pressure Processing of Orange Juice: Kinetics of Pectinmethylesterase Inactivation

ABSTRACT: A kinetic study of pectinmethylesterase (PME) inactivation in orange juice was conducted. Juice samples were subjected to combinations of high pressure (400, 500, 600 MPa) and thermal (25, 37.5, 50 °C) treatments for various time periods. PME inactivation followed a first-order kinetic model with a residual activity of pressure-resistant enzyme remaining. Calculated D-values ranged from 4.6 min to 117.5 min at 600 MPa/50 °C and 400 MPa/25 °C, respectively. Pressures in excess of 500 MPa resulted in sufficiently fast inactivation rates for economic viability of the process.     

橙汁混浊的稳定性

研究成熟度、制汁工艺、酶处理、贮藏条件对橙汁混浊稳定性影响。结果表明：随着成熟度增加,橙汁混浊度呈上升趋势;胶体磨细微化可以增加果浆中果胶、可溶性果胶的溶出,果胶含量显著增加(P ＜ 0.05);果胶酯酶(PE)活性影响橙汁混浊稳定性,应完全钝化;采用果胶酶酶解会破坏橙汁浑浊稳定性,木瓜蛋白酶酶解橙汁浑浊度的影响不明显;4℃和15℃贮藏对橙汁混浊度的影响不显著(P ＞ 0.05),25℃贮藏对橙汁混浊度降低影响显著(P ＜ 0.05),常温贮藏不利于保持橙汁混浊稳定性。     

High-Pressure Processing of Orange Juice: Combination Treatments and a Shelf Life Study

ABSTRACT: Several process alternatives for the stabilization of fresh orange juice at pressures between 500 MPa and 800 MPa and temperatures between 25 and 50 °C were evaluated. Processing at 800 MPa and 25 °C for 1 min and use of thermally pasteurized pulp yielded the lowest level of residual pectinmethylesterase activity (3.9%) and good cloud stability at 4 and 37 °C over a period of more than 2 mo. Ascorbic acid loss was less than 20% after storage for 3 mo at 4 °C or 2 mo at 15 °C. Color values were stable during storage at 4, 15, and 26 °C     

A Continuous High Pressure Carbon Dioxide System for Microbial Reduction in Orange Juice

ABSTRACT: A continuous high-pressure carbon dioxide system, run at ambient conditions, was tested on its performance in reducing both natural and inoculated microbial loads. The prototype system continuously processes orange juice with carbon dioxide (CO₂) at high pressures. A central composite design was originally used to examine the variables of pressure, residence time, and CO₂/juice ratio. For microbial reduction, residence time was the major factor followed by pressure. The CO₂/juice ratio showed no influence on microbial load, and in this equipment, was difficult to control. The unit was able to cause a 5-log reduction of the natural flora in spoiled juice, and could attain a 5-log decrease in numbers of pathogenic Escherichia coli O157:H7, Salmonella typhimurium , and Listeriamonocytogenes . No viable cells of E . coli O157:H7 orS. typhimurium were cultured after the treated juices were stored at room temperature (22 °C) for 14 d. Thus, non-thermal pathogen reduction is possible with this system.     

柑桔汁悬浮稳定机理的探讨

柑桔汁的混浊稳定机理研究 .结果表明 ,均质可以降低柑桔汁悬浮颗粒的大小 ,从而提高产品的稳定性 ,但是均质的压力高于 1 9.6MPa时 ,悬浮颗粒过小 ,贮存期间颗粒易合并而破坏混浊稳定性 .添加蔗糖可以增大柑桔汁的密度 ,稳定剂可以提高柑桔汁的粘度 ,从而降低了悬浮颗粒沉降速度 ,提高产品的稳定性 .研究还发现 ,复配稳定剂对柑桔汁稳定作用优于单一稳定剂 ,这是因为大分子之间产生协同作用所致     

Multiple Forms of Pectinmethylesterase from Citrus Peel and Their Effects on Juice Cloud Stability

Heparin chromatography of a dialysis supernatant fraction from total salt extractable proteins of Citrus sinensis (L.) Osb. var. Valencia fruit peel (flavedo plus albedo) resolved four peaks of pectinmethylesterase activity (PME 1–4). One of these was thermally tolerant (PME 3). Binding to concanavalin A suggested PME 3 was a glycoprotein. At 30°C and 5 U - mL1 PME 1, 2 and 3 destabilized the cloud of pasteurized FCOJ within 10 days. PME 1 caused the most rapid cloud loss (3d), followed by PME 3 and PME 2. PME 4 had no effect on juice cloud during this time period. At 4°C PME 3 caused the most rapid cloud loss (3d), followed by PME 1 (14d) and PME 2 (>14d). PME 4 had no effect on juice cloud stability after 10 days at 30°C or 14 days at 4°C.     

Effects of Carbon Dioxide in High-Pressure Processing on Pectinmethylesterase in Single-strength Orange Juice

ABSTRACT: High-pressure processing (HPP) in combination with added CO was examined for efficacy in inactivating Valencia orange juice pectinmethylesterase (PME). Noncarbonated juice and carbonated juice were subjected to a range of conditions from 200 to 600 MPa, 30 to 300 s dwell time at pressure, and 15 to 50 °C at final processing temperature. Processing pressure magnitude, temperature, and dwell time were significant factors (p < 0.001) in the inactivation of PME. At 600 MPa and 25 °C final processing temperature, the addition of 12 psig carbon dioxide resulted in a decrease of pressure processing time from 346 s to 111 s, while achieving an equivalent reduction in PME activity.     

Physical/Chemical Nature of Pectin Associated with Commercial Orange Juice Cloud

The cloud pectin content of two commercial orange juice concentrates was 4.7 and 4.3%. The cloud pectin was solubilized to varying degrees in 6% citric acid. pH 2.5; in 10M urea-6% citric acid, pH 2.5; by hydrolysis of cloud protein with protease; and in sodium oxalate; pH 4.5. Much of the urea-solubilized pectin reprecipitated upon dialysis. The binding of orange cloud to amino paramagnetic latex particles demonstrated a clear association of cloud pectin with cloud protein. Simulation of orange juice processing conditions indicated that some of the cloud pectin arises from the pulp during processing. About 60% of the cloud pectin is soluble pectin that has become associated with cloud protein, 25–30% is calcium pectate and 15% is protopectin.     

A Continuous High-Pressure Carbon Dioxide System for Cloud and Quality Retention in Orange Juice

ABSTRACT:  Orange juice (OJ) was treated with a continuous high-pressure carbon dioxide (HPCD) system, and the quality parameters pH, Brix, titratable acidity (TA), cloud, pectinesterase (PE) activity, color, and sensory attributes were determined. Treatment pressures were 38, 72, and 107 MPa, and CO₂/juice (w/w) ratios were from 0.40 to 1.18. Residence time was kept at 10 min. Cloud increased between 446% and 846% after treatments. There were no significant changes in pH and Brix (α= 0.05). TA of the treated juice was found to be significantly different from that of control (α= 0.01). PE was not completely inactivated. There was a small, but significant increase in juice L-value (α= 0.01) and a decrease in a-value for color. There was no significant change in b-values (α= 0.05). Statistical analysis for the sensory data showed no difference between fresh, frozen control juice and treated juice after 2 wk of refrigerated storage at 1.7 °C.     

超高压和高温短时杀菌对NFC橙汁品质的影响

本文对比了超高压(Ultral high pressure processing,HPP,600 MPa,1 min)和高温短时(High temperature short time,HTST,110 ℃,8.6 s)杀菌处理对非浓缩还原(Not from concentrate,NFC)橙汁处理前后及4 ℃、25 ...     

Effect of Thermal Processing and Carbon Dioxide-assisted High-pressure Processing on Pectinmethylesterase and Chemical Changes in Orange Juice

ABSTRACT: The effects of high-pressure processing (HPP), CO₂-assisted high-pressure processing (HPP + CO₂), and thermal processing on the chemical and physical properties of single-strength Valencia orange juice were evaluated over 4 mo of storage at 4 and 30 °C. The HPP + CO₂ juice had the greatest cloud stability and highest ascorbic acid retention. Volatile compound losses were lowest in the HPP juice and lower in the HPP + CO₂ juice compared to the thermally processed juice (p < 0.05). HPP + CO₂ produced a cloud-stable orange juice with more ascorbic acid and flavor volatiles than thermally processed juice (p < 0.05).     

超高压处理对鲜橙汁中果胶酶及过氧化物酶活性的影响

为推进国内非冷冻浓缩橙汁加工业的发展,对新型超高压杀菌技术对橙汁中酶钝化的效果进行研究,采用200～600MPa超高静压处理鲜榨橙汁,使用紫外分光光度法、滴定法分别测定鲜橙汁中过氧化物酶(POD)和果胶酶(PME)的活性,进行两种酶在常温下超高压钝化酶一级动力学拟合研究。结果表明：在常温条件下200MPa处理10min使两种酶轻微激活,在300～600MPa条件下,随压力和处理时间的增大,两种酶钝化反应明显,且符合一级动力学模型,且果胶酶对压力钝化更加敏感。     

超高压处理对脐橙汁中香气成分柠檬烯的影响

以脐橙汁为对象,采用Box-behnken 响应曲面设计,研究超高压处理对橙汁中柠檬烯香气成分的影响,实验参数选择压力(100～500MPa)、温度(20～40℃)、处理时间(10～20min),建立超高压处理下柠檬烯含量变化的二次多项数学模型。结果表明：模型的确定系数R2=0.9938,调整确定系数RAdj=0.9858,方差分析表明模型极度显著(P ＜ 0.0001),该模型可用于超高压处理橙汁中柠檬烯含量变化的分析与预测。     

Citrus Tissue Extracts Affect Juice Cloud Stability

Salt extractable proteins were isolated from hand expressed juice, rag and peel of Valencia oranges. Each tissue extract was divided into dialysis supernatant (DS) and precipitate (DP) (forms during dialysis). DP, DS and DS heated for 2 min at 80°C (HDS) were added to pasteurized, reconstituted frozen concentrated orange juice at 5 U · mL^?1 of pectinmethylesterase. Samples were incubated either at 25°C for 14 days or 4°C for 28 days and periodically sampled to determine the effects of tissue extracts on juice cloud stability. Tissue specific differences were observed for the rate of juice cloud precipitation and among the HDS, DS, and DP fractions of a given tissue. HDS fractions destabilized juice cloud more rapidly than DS or DP at both 25 and 4°C.     

超高压处理对橙囊胞香气成分的影响

为了了解橙囊胞经超高压处理后香气成分产生的变化及其原因,采用气相色谱-质谱联用分析法检测分析其中的香气成分。结果表明:橙囊胞的主要香气成分为柠檬烯、凡伦橘烯、人参烯、丁酸乙酯、葵醛、香芹酮、芳樟醇和松油醇,其中柠檬烯占62.68%,是最主要的香气成分。超高压处理后,香气成分发生变化,醇类质量分数变化相对较少,烯类和酯类的种类和数量都明显减少,其中柠檬烯经500 MPa高压处理5 min后质量分数下降了89.8%,而醛酮类则都增加,其中香芹酮经300 MPa处理15 min后质量分数增加了13倍,上述影响作用跟高压造成的温度升高有关,同时结果也表明,300 MPa超高压处理5 min的样品更接近对照样品的风味。     

High Pressure Inactivation Kinetics of Saccharomyces cerevisiae Ascospores in Orange and Apple Juices

High pressure inactivation kinetics (D and z values) of Saccharomyces cerevisiae ascospores were determined in fruit juices and a model juice buffer at pH 3.5 to 5.0. Approximately 0.5 to 1.0 × 10⁶ ascospores/mL were pressurized at 300 to 500 MPa in juice or buffer. D-values ranged from 8 sec to 10.8 min at 500 and 300 MPa, respectively. The range for z-values was 115 to 121 MPa. No differences (P≥0.05) in D (at constant pressure) or z-values among buffers or juices at any pH were determined, indicating little influence of pH in this range and absence of protective or detrimental effects of juice constituents.     

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%)。     

酶处理对橙汁混浊稳定性及微观结构的影响研究(英文)

橙汁因其均匀稳定混浊态的丧失而失去诱人外观。本文以橙汁为原料,采用果胶酶及蛋白酶处理,比较其混浊态稳定性及微观结构的变化。结果表明:果胶酶可加速橙汁的澄清,蛋白酶处理可减缓橙汁混浊态的丧失。经过酶处理后橙汁溷浊的微观结构发生了变化,用蛋白酶处理后的橙汁混浊体积较小,分布较均匀,呈筛状的网状结构;而用果胶酶处理后的橙汁形成了体积稍大的无定形物质且混浊成分之间有游离脂肪滴。脯氨酸是橙汁中含量最高的氨基酸,其可能与橙汁混浊中蛋白质的不溶有关。     

高压CO_2处理对西瓜汁的影响

以海南麒麟西瓜为原料,榨汁后进行HPCD(高压CO2)杀菌处理,处理温度为25℃,压力为20 MPa和30 MPa,处理时间分别为10、30和60 min,测定HPCD处理后西瓜汁的主要理化指标、细菌总数和PME酶(果胶甲基酯酶)活性变化。结果表明:HPCD处理后西瓜汁pH值降低0.3～0.7、可溶性固形物无明显变化、颜色更红、浊度增加,细菌总数降低可达到2个对数,果胶甲基酯酶活性可降低50%。