橙汁混浊稳定性的研究进展

橙子榨汁后,果肉颗粒、细胞壁碎片、橙油微滴、橙皮苷结晶、细胞色素及一些无定形物质不均匀的分散于水中,使橙汁呈现特殊的不透明或混浊状态,即"橙混浊态"。橙混浊态能提供橙汁的大部分味道、颜色、质地、香气。若橙汁中颗粒过大,会导致橙汁沉降,产生橙汁混浊稳定态丧失现象。本文综述了橙混浊态主要组分,包括果胶、蛋白质、纤维素、橙皮苷等,还介绍了橙混浊态特性及影响橙汁混浊稳定性因素,包括果胶甲酯酶作用、甜橙品种与成熟度、酸度和钙离子、橙混浊态稳定剂。同时对在加工及贮藏过程中能够保持橙汁混浊稳定性相关方法,如添加果胶甲酯酶抑制剂及使用超高压均质、超声灭菌等"冷杀菌"技术进行全面综述。通过继续深入研究橙混浊态中各组分相互作用机制和橙汁加工新技术,可进一步改善橙汁在加工、贮藏过程中的混浊稳定性,使橙汁饮品在货架期保持较好状态。     

橙汁混浊态丧失机理的研究进展

橙汁混浊态的丧失是影响橙汁消费的重要原因。综述了果胶酯酶、橙汁混浊物等对橙汁混浊态影响的研究进展，旨在改善橙汁及其饮料的质量及为其它混浊汁研究提供一定理论依据。     

仙人掌橙汁复合饮料加工工艺的研究

以"米邦塔"仙人掌茎和橙汁为试材,进行淀粉酶和果胶酶处理提高仙人掌出汁率、仙人掌草腥味掩盖、仙人掌橙汁复合饮料稳定性和杀菌实验,探讨仙人掌橙汁复合饮料的加工工艺.结果表明:淀粉酶和果胶酶处理对混浊仙人掌汁出汁率的影响不明显;β-环状糊精对仙人掌的草腥味的掩盖无效果,而添加2倍于仙人掌汁的橙汁可以掩盖大部分的仙人掌草腥味;仙人掌橙汁复合饮料的稳定剂组合为0.20%CMC 0.20%海藻酸钠时其稳定性和口感最好;90℃维持2min杀菌,趁热灌装,常温下保质期达6个月以上.     

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。     

橙汁可溶性成分对橙汁混浊稳定态的影响研究

通过模拟体系,研究了橙汁中各可溶性成分对其混浊稳定性的影响,研究发现,橙汁可溶性成分对橙汁混浊态的影响程度为:柠檬酸>Ca2 >K >柠檬酸×Ca2 >蔗糖>柠檬酸×K >柠檬酸×可溶性果胶>可溶性果胶。     

橙汁可溶性成分橙汁混浊稳定态的影响研究

通过模拟体系,研究了橙汁中各可溶性成分对其混浊稳定性的影响,研究发现,橙汁可溶性成分对橙汁混浊态的影响程度为柠檬酸＞Ca2+＞K+＞柠檬×Ca2+＞蔗糖＞柠檬酸×K+＞柠檬酸×可溶性果胶＞可溶性果胶.     

水酶法提取菜籽油预处理工艺及酶复配研究

采用水酶法技术从双低油菜籽中提取油,在扫描电镜对菜籽颗粒微观结构进行分析的基础上,研究了不同预处理方式、酶品种对油脂提取率的影响.结果表明:脱皮菜籽先干法粗破碎,沸水处理10min.再用组织捣碎机粉碎后.用细胞壁多糖酶(聚糖酶+果胶酶)与蛋白酶先后作用于菜籽,油脂提取率最高,达到90.99%.     

某些酶制剂对葡萄酒稳定性的影响(文摘)

文章提出了用臭曲果胶素即果胶酶制剂与泡盛蛋白酶(酸性蛋白酶)来降低引起葡萄酒混浊重要物质的含量。葡萄酒用所述酶制剂处理后,观察到蛋白质降低15～30％,胶体降低20～30％,聚苯酚降低15～30％。随着试验的葡萄酒试料的化学组成改变的同时发生感官性质的改善,从而提高高浓度葡萄酒的稳定性。     

超高压处理对鲜榨橙汁品质的影响

研究比较超高压处理和热处理对鲜榨橙汁品质的影响。研究结果表明：鲜榨橙汁经处理后,其主要成分都呈现不同程度的损失,但超高压处理鲜榨橙汁效果较热处理好,且对色泽影响较小;鲜榨橙汁经处理后,其香气成分发生了变化,酯类、醇类、酮类总含量变化相对较小,醛类经热处理及超高压处理后与鲜榨橙汁比较有所降低,降低比例都在4倍以上;烃类及其它类物质含量与鲜榨橙汁比较也有所下降。     

亲水性胶体对橙汁饮料稳定性的影响

目的以30%橙汁饮料为对象,研究结冷胶、黄原胶、海藻酸钠等亲水性胶体对橙汁稳定性的影响。方法采用U8(88)均匀设计筛选出对橙汁稳定性影响最为显著的因素,再通过L9(34)正交设计进一步验证优化橙汁饮料中的胶体最佳复配方案。结果对橙汁沉淀影响最为显著的胶体是海藻酸钠、结冷胶、果胶、黄原胶,而瓜尔胶、阿拉伯胶和羧甲基纤维素钠(CMC)的影响不显著,其中结冷胶和黄原胶有利于橙汁的混浊稳定性,但是黄原胶和CMC的加入会促进橙汁的絮凝产生。海藻酸钠和结冷胶是影响橙汁稳定性的重要因素,一定用量的海藻酸钠和结冷胶复配能很好抑制产品沉淀,维持体系的混浊稳定性;黄原胶是引起产品絮凝的主要因素,适量的果胶和海藻酸钠可以防止絮凝形成。结论在海藻酸钠、结冷胶和果胶添加量分别为1.2‰、0.32‰和0.8‰时,橙汁具有最佳稳定性,产品的沉淀量最少,混浊稳定性最高,同时可最大程度防止絮凝。经过验证,在最优胶体复配条件下,其沉淀稳定性为98.52%,混浊稳定性达94.89%,产品无明显絮凝。     

Comparing equivalent thermal, high pressure and pulsed electric field processes for mild pasteurization of orange juice. Part I: Impact on overall quality attributes

Mild heat pasteurization, high pressure processing (HP) and pulsed electric field (PEF) processing of freshly squeezed orange juice were comparatively evaluated examining their impact on microbial load and quality parameters immediately after processing and during two months of storage. Microbial counts for treated juices were reduced beyond detectable levels immediately after processing and up to 2 months of refrigerated storage. Quality parameters such as pH, dry matter content and brix were not significantly different when comparing juices immediately after treatment and were, for all treatments, constant during storage time. Quality parameters related to pectinmethylesterase (PME) inactivation, like cloud stability and viscosity, were dependent on the specific treatments that were applied. Mild heat pasteurization was found to result in the most stable orange juice. Results for HP are nearly comparable to PEF except on cloud degradation, where a lower degradation rate was found for HP. For PEF, residual enzyme activity was clearly responsible for changes in viscosity and cloud stability during storage.

Industrial relevance

Development of mild processing technologies with a minimal impact on fruit juice can be considered as a true alternative of fresh fruit. The present work presents a fair comparison of mild heat treated, high pressure (HP) and pulsed electric field (PEF) processed orange juice as an alternative for thermal pasteurization. Orange juices were monitored during two months of storage.     

Stable Clouding Agent from Isolated Soy Protein

In a dilute suspension the stability of soy protein particles equalled or surpassed that of orange juice prepared from concentrate during short-term storage at 4°C. Soluble soy protein produced a stable cloud only when soluble pectin was present in the incubation medium as the particles were forming. In the absence of soluble pectin the nascent soy protein particles rapidly aggregated. This soy protein based clouding agent may provide a natural and healthy alternative to oil-derived clouding agents. The stabilization of such suspended soy protein particles also provides a model system that may be comparable to orange juice cloud for stability studies.     

An exploratory study on the influence of orange juice on gut microbiota using a dynamic colonic model

The aim of this research was to evaluate the influence of fresh orange juice (FOJ) and pasteurized orange juice (POJ) on gut microbiota using the Simulator of the Human Intestinal Microbial Ecosystem (SHIME®) in a long-term experiment. SHIME® vessels were used to investigate orange juice fermentation throughout the colon and to assess changes in microbial composition and fermentation metabolites (short-chain fatty acids, or — SCFA, and ammonium). Antioxidant activity of the SHIME® vessels and juice was also evaluated. The FOJ increased (p ≤ 0.05) Lactobacillus spp., Enterococcus spp., Bifidobacterium spp., and Clostridium spp. and reduced (p ≤ 0.05) enterobacteria. The POJ increased (p ≤ 0.05) Lactobacillus spp. and reduced (p ≤ 0.05) enterobacteria. The PCR-DGGE analysis showed a reduction in total bacteria population richness values. The FOJ and POJ increased (p ≤ 0.05) butyric, acetic, and propionic acid concentrations, whereas ammonium production was reduced. High values of antioxidant activity were observed as a result of the FOJ and POJ treatments. Principal component analysis indicated that both POJ and FOJ juices had a positive influence on gut microbiota. The FOJ and POJ were found to exhibit selective prebiotic activity, particularly in terms of gut microbiota. This finding is in agreement with increases in both SCFAs and commensal bacteria, as well as with decreases in ammonium levels, though total bacteria richness values were reduced.     

Apple Juice Clarification With the Use of Honey and Pectinase

The clarification of apple juice with the use of honey and enzyme separately and in combinations was studied. The results indicated the existence of a synergistic effect upon the time of initial flocculation when honey was combined with pectinase enzymes. Changes in the rate of flocculation appeared to be an additive effect of enzyme concentration and/or honey concentration. The combined treatment of honey and enzyme was found to induce flocculation very fast as compared to enzyme alone at cold as well as warm temperatures. When used alone, the honey treatment produced a clarified juice with a viscosity similar to cider.     

果胶酶制剂在澄清苹果汁加工中的应用研究

利用果胶酶制剂处理苹果(品种:国光)、果浆、果汁,结果表明:0.1％的Pectinex Ultra SP果胶酶处理可明显地提高出汁率、可溶性固形物和透光度;降低pH值和相对粘度,处理效果随作用时间增加而增加,对不同贮藏期的苹果处理效果不同。0.1％的TL-enzyme果胶酶与0.1％的纤维素酶结合处理的效果大于0.1％的TL-enzyme果胶酶单独处理的效果。在20～22℃,汁中添加不低于0.1％的黑曲霉(As 3.316)果胶酶或不低于0.001％的Ultrazym100G果胶酶,可分别在8小时和6小时内使果汁澄清;处理温度提高或酶浓度加大,澄清时间缩短。用Ultrazym100G果胶酶澄清的汁,其糖分、滴定酸含量没有明显变化,单宁物质含量降低,矿质元素和沉淀中粗蛋白含量发生变化。     

Optimization of Carrot Juice Color and Cloud Stability

Investigations were conducted on the effects of heating, acidification, and enzyme treatment on carrot juice color and cloud stability. Heating whole carrots to 93°C prior to milling and pressing improved juice color, but reduced juice yield compared to heating milled carrots to 93°C. Juice color was improved by acidification of milled carrots to pH 5 or 4 with citric acid prior to pressing. Juice from carrots heated before milling clarified quickly if not acidified before pressing. Acidification after juice extraction did not stabilize cloud. A commercial pectinase/hemicellulase preparation improved juice color, but not juice yield. Only 20% of potential β-carotene was extracted from carrots during pressing, and β-carotene was extracted to a greater extent than α-carotene.     

Survival of Escherichia coli O157:H7 during storage in pressure-treated orange juice.

The effect of a high-pressure treatment on the survival of a pressure-resistant strain of Escherichia coli O157:H7 (NCTC 12079) in orange juice during storage at 3 degrees C was investigated over the pH range of 3.4 to 5.0. The pH of shelf-stable orange juice was adjusted to 3.4, 3.6, 3.9, 4.5, and 5.0 and inoculated with 10(8) CFU ml(-1) of E. coli O157:H7. The orange juice was then pressure treated at 400 MPa for 1 min at 10 degrees C or was held at ambient pressure (as a control). Surviving E. coli O157:H7 cells were enumerated at 1-day intervals during a storage period of 25 days at 3 degrees C. Survival of E. coli O157:H7 during storage was dependent on the pH of the orange juice. The application of high pressure prior to storage significantly increased the susceptibility of E. coli O157:H7 to high acidity. For example, after pressure treatment, the time required for a 5-log decrease in cell numbers was reduced from 13 to 3 days at pH 3.4, from 16 to 6 days at pH 3.6, and from >25 to 8 days at pH 3.9. It is evident that the use of high-pressure processing of orange juice in order to increase the juice's shelf-life and to inactivate pathogens has the added advantage that it sensitizes E. coli O157:H7 to the high acid conditions found in orange juice, which results in the survival of significantly fewer E. coli O157:H7 during subsequent refrigerated storage.     

Calcium Supplementation and Processing Variable Effects on Orange Juice Quality

Untreated, pectinesterase treated, low pulp, and pectinase treated orange juices were fortified to 20% RDA of calcium with calcium carbonate or calcium phosphate/lactate (75/25). Neither calcium supplement adversely affected flavor, cloud density, settling pulp, or viscosity in untreated, low pulp, or pectinase treated juices. PME exposed orange juice held 4 hr before pasteurization and calcium supplementation had less cloudy density, increased viscosity and more settling pulp. Calcium carbonate fortified PME exposed and pectinase treated juices had lower flavor scores, while calcium phosphate suspensions caused slightly lower color scores of all juices.     

Quality degradation kinetics of pasteurised and high pressure processed fresh Navel orange juice: Nutritional parameters and shelf life

A kinetic study of post processing quality loss was conducted after high pressure processing (600 MPa, 40 °C, 4 min) or thermal pasteurisation (80 °C, 60 s) of fresh Navel orange juice. Selection of processing conditions was mainly based on pectin methylesterase inactivation. Ascorbic acid loss, colour, viscosity and sensory characteristics were measured during storage at different isothermal conditions (0–30 °C). Increased shelf life (based on ascorbic acid retention) was achieved for high pressurised compared to thermally pasteurised juice, ranging from 49% (storage at 15 °C) to 112% (storage at 0 °C). Activation energy values for ascorbic acid loss were 68.5 and 53.1 kJ/mol, respectively, for high pressurised and thermally treated juice. High pressure processing resulted in better retention of flavour of untreated juice and superior sensory characteristics compared to thermal pasteurisation. Colour change was linearly correlated to ascorbic acid loss for both types of processing. Slightly higher apparent viscosity values were determined for high pressurised juice.Industrial relevanceApplication of high hydrostatic pressure on orange juice industry. Fresh orange juice is a product of high commercial and nutritional value due to its rich vitamin C content and its desired sensory characteristics. High Hydrostatic Pressure (HHP) is an alternative non-thermal technology that has been proposed for application on orange juice. Such a treatment denaturates enzymes and eliminates microorganisms responsible for spoilage of orange juice without detrimental effects on the sensory and nutritional quality of juice. The effect of HHP on the stability of fresh orange juice has been studied by different research groups, while orange juices processed with the new technology have already been commercially available in Japan, U.S.A., Mexico and Europe. However, a systematic kinetic approach of the effect of HHP on different quality indexes (not only microbial spoilage) immediately after processing, as well as during a long term storage of the processed orange juice is needed, in order to achieve an optimal process design and a successful application of the new technology in orange juice industry. Such kinetic data for parameters related to the quality and nutritional value of fresh orange juice were gathered in the present work providing therefore industry with useful information for the HHP stabilization of orange juice and the production of a high quality product. Due to the great benefits of HHP compared to the conventional pasteurization that emerged from this work regarding the quality, shelf life and nutritional characteristics of fresh orange juice, HHP technology is an advantageous alternative process for high valued products like orange juice.