Viscosity Reduction and Reformation of Structure in Orange Concentrate as Affected by Homogenization within Commercial Taste Evaporators

Experiments were undertaken to determine, if homogenization would reduce viscosity of bulk orange concentrate during commercial production and if a structure built-up during storage. Homogenizers, installed within two Taste evaporators at separate citrus processing plants, were cycled “on” for homogenized samples and “off” for controls. In four replicates, homogenization significantly reduced viscosity 19% average. Samples were stored 6 months under tank farm conditions. Structure increased in 5 of 8 samples, but homogenized samples remained significantly lower in viscosity. This confirmed earlier pilot plant results under commercial operations.     

Storage Stability of Orange Juice Concentrate Packaged Aseptically

Orange juice concentrates were packaged aseptically by a “Dole” aseptic canning machine using 6 oz metal cans. The final juice products (11°, 34°, 44°, 58° Brix) were stored between ?18° and 36°C and tested periodically for nonenzymatic browning, ascorbic acid destruction, furfural and sensory changes. Nonenzymatic browning, the main deterioration phenomena in these products, was satisfactorily retarded at 12°C or lower. Ascorbic acid destruction rate constant was dependent on temperatures between 5 and 25°C, and was affected by degree of juice concentration. Furfural accumulation in juice was higher than that in 58° Brix concentrate. Orange juice concentrate of 58° Brix did not show flavor changes after storage at 5°C or 12°C for 17 or 10 months, respectively, when evaluated after reconstitution to 11° Brix.     

浓缩橙汁贮藏过程中非酶褐变的研究

研究了浓缩橙汁在不同贮藏条件下与非酶褐变有关的主要物质的变化及其与褐变的关系。通过相关性分析和通径分析,探求引起浓缩橙汁褐变的主要原因。实验表明,抗坏血酸的氧化降解,类胡萝卜素的降解,酚类物质的氧化缩合是引起褐变的主要因素,美拉德反应对褐变的影响较小。     

基于PCR-CE技术的NFC橙汁与FC橙汁鉴别

摘 要：以特洛维塔、早金、哈姆林3 种甜橙为原料,按照市售橙汁的主要生产工艺,模拟制备非复原（not from concentrated,NFC）橙汁和复原（from concentrated,FC）橙汁。针对甜橙叶绿体成熟酶K蛋白基因（maturase K,matK）和烟酰胺腺嘌呤二核苷酸脱氢酶基因（nicotinamide adenine dinucleotide dehydrogenase,ndhF）,共设计8 对引物用以扩增得到不同长度的目标条带,结合聚合酶链式反应（polymerase chain reaction,PCR）和毛细管电泳（capillary electrophoresis,CE）技术分析了鲜榨、均质、巴氏杀菌、浓缩、二次巴氏杀菌关键加工工艺,对特洛维塔橙汁叶绿体matK和ndhF基因的DNA降解变化的影响,探讨NFC橙汁与FC橙汁DNA降解程度的差异,筛选出NFC橙汁和FC橙汁的特征差异性片段组,建立基于PCR-CE技术的NFC橙汁与FC橙汁鉴别方法。该方法适用于分析货架期内的NFC橙汁与FC橙汁,且同样适用于早金和哈姆林甜橙为原料的NFC橙汁与FC橙汁的鉴别。应用该方法对市售NFC橙汁进行检测,发现市售NFC橙汁存在标签不符的现象。本研究建立的基于PCR-CE技术的NFC橙汁与FC橙汁定性鉴别方法可以为果汁行业的有效监管提供技术支撑。     

Preparation and Storage of 72° Brix Orange Juice Concentrate

Each year, thousands of tons of citrus concentrate are stored and transported throughout the world at 62° Brix. Increasing this concentration to 72° Brix can result in substantial savings. Fresh orange juice, treated mechanically or with pectic enzymes to reduce its viscosity, was concentrated to 72° Brix in a commercial processing plant, then samples were stored in barrels in a tank farm at ?7 or at 4°C. At monthly intervals, samples were blended to make 41.8° Brix Frozen Concentrated Orange Juice. The enzyme-treated samples had lower viscosity than those mechanically treated. Vitamin C retention levels were > 94% after 6 months storage at 4°C. Taste evaluations rated the product ‘very good’ and furfural levels were well below that which indicates off flavors. Browning tended to increase with storage time and temperature.     

碳水化合物对浓缩橙汁的玻璃化转变温度和粘度的影响

研究了浓缩橙汁中的碳水化合物组成以及它们对产品的玻璃化转变温度和粘度的影响 .由压榨工艺和酶法工艺制备的浓缩橙汁在含量较少的大分子碳水化合物的组成上存在明显差异 ,而在含量占优势的低分子量化合物的组成上却很相似 .两种橙汁的玻璃化转变温度相近 ,但酶法工艺所制得橙汁的粘度明显高于前者 .添加平均相对分子质量为 3 60 0的麦芽糊精M0 4 0能提高浓缩橙汁的玻璃化转变温度 ,但幅度不大 ,而产品的粘度却能显著上升 .     

Pilot Plant Production of an Edible Alfalfa Protein Concentrate

This paper reports the development of a pilot plant scale wet fractionation process to obtain an edible leaf protein concentrate from alfalfa juice by the fractionated recovery of the chloroplastic and cytoplasmatic proteins. The green pigmented fraction is recovered at room temperature by employing an organic polyelectrolyte, while the edible white proteins are coagulated by acidification to pH 4.0. The pilot plant and working conditions are described together with the chemical composition of the final products. Some functional properties of cytoplasmatic protein concentrate are also reported. Since the whole process takes place at room temperature the cytoplasmatic protein concentrate shows good functional properties especially with regard to its nitrogen solubility.     

Frozen Concentrated Orange Juice (FCOJ) Processed by the High Pressure Homogenization (HPH) Technology: Effect on the Ready-to-Drink Juice

The high pressure homogenization (HPH) process can be used to reduce the consistency of frozen concentrated orange juice (FCOJ), which is highly desirable in industrial processing due to the reduction in energy costs. The production of FCOJ is almost entirely destined to obtaining the reconstituted (ready-to-drink (RTD)) juice. Consequently, this study aimed to evaluate the effect of the HPH processing on the ready-to-drink juice. FCOJ (66°Brix) was processed by HPH up to 150 MPa and then diluted to 11°Brix for evaluation. The RTD juice was evaluated by pulp sedimentation, instrumental colour, turbidity (serum cloudiness), rheological properties and sensorial perception. The HPH process decreased the absorbance of the serum phase, which was related to the disruption of the suspended particles. Further, the process slightly reduced the RTD juice viscosity. However, the HPH showed no effect on the product colour, pulp sedimentation behaviour and sensorial perception (visual aspect, odour, flavour, viscosity, overall liking). Therefore, it was concluded that the HPH process can be used to promote desirable effects on FCOJ, without affecting the RTD juice properties.     

Flow Properties of Low-Pulp Concentrated Orange Juice: Serum Viscosity and Effect of Pulp Content

65° Brix serum samples from four concentrated orange juice (COJ) samples, between -19 and 30°C, were mildy shear-thinning fluids with negligible yield stress. The power law model described well the flow data. For one sample, the Powell-Eyring model also described the data. The activation energy of flow (E_a) for the samples was between 11.2–13.6 kcal/gmole. The power law parameters were determined for a 65°Brix sample as a function of pulp content (0–11%) between −19 and 30°C. At a fixed temperature, the apparent viscosity and the consistency index increased exponentially with pulp content. E_a decreased with increase in pulp content and reached a constant value of about 10.2 kcal/gmole. Data on a high-pulp (21.2%), 65° Brix, sample indicated the presence of yield stress, particularly at low temperatures. The Mizrahi-Berk model predicted reliable values of the yield stress.     

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.     

高效液相色谱法测定柑橘汁糖的组成

研究了柑橘汁中糖组成的高效液相色谱测定方法。采用固相萃取小柱预分离干扰成分,以AgilentZorbaxCarbohydrate(4.6×250mm,5μm)糖分析柱为固定相,80%乙腈为流动相,柱温25±2℃。本方法的相对标准偏差0.83%～1.71%,标准回收率96%～103%。该方法简便快速,结果准确可靠,为果汁中糖组成分析提供了一种高效快速的测定方法。     

利用顶空固相微萃取/气相色谱-质谱法检测脐橙汁中柠檬烯香气成分

本实验研究了顶空固相微萃取(HS-SPME)对橙汁中柠檬烯成分的分析,并且对SPME纤维头、萃取温度、萃取时间、盐效应等因素进行了实验。结果表明应用PDMS(聚二甲基硅氧烷)100μm萃取头,加入饱和电解质NaCl(0.3g/ml),在50℃萃取30min,柠檬烯萃取和检测效果最好。对方法加标回收率、线性范围、重复性进行研究,表明方法灵敏性和重现性好。该方法快速简便,可作为橙汁中柠檬烯检测的一种依据。     

Estimation of Microbial Populations in Orange Juice by Bioluminescence

Bioluminescent measurement of microbial ATP was compared to plate counts of orange juice on orange serum agar and plate count agar plus chloramphenicol and chlortetracycline. Bioluminescent values correlated well (r = 0.92) with plate counts of reconstituted juices with active microbial populations. A correlation of 0.58 was found for bioluminescent values to plate counts for orange juice samples immediately after reconstitution from concentrate. Centrifugation and resuspension of samples in 0.1M Tris-HCl buffer, pH 8.0, was utilized to provide adequate pH adjustment and concentration of microorganisms for bioluminescent measurement.     

用中空纤维超滤膜法澄清橙汁

对中空纤维超滤膜法澄清橙汁(Citrus sinensis)进行了研究。试验着重研究了操作压力、温度、物料浓度和进料流速对膜透过速率的影响,并测定了超滤(?)中的营养成分的保存率。还探讨了超滤作为膜蒸馏浓缩预处理的可能性。结果表明,超滤法澄清橙汁是可行的．对果汁营养成分及风味无显著影响。由于超滤除去了果胶等固形物,因此能提高膜蒸馏过程的蒸馏通量。     

Hyperfiltration of Tomato Juice: Pilot Plant Scale High Temperature Testing

A two-stage tubular hyperfiltration (reverse osmosis) pilot plant equipped with 15.6 m² of aromatic polyamide thin film composite membrance (ZF 99) was studied with tomato juice (4–6% natural tomato soluble solids [NTSS]). It was operated over 100 hr in recirculation and single pass modes. The single pass mode was operated at33–38 bar (feed inlet pressure) and 70–93°C for 18.2 hr. Stage 1 flux was 48 to 34 Lm^?2hr^?1. Stage 2 flux was 30 to 20 Lm^?2hr^?1. Concentration went to 7.4–9.0% NTSS at 8.6 L/min, and to 6.3–6.4% NTSS at 18.6 L/min. NTSS rejection was >98%. Of permeate samples tested none showed detectable levels of sugars; only 25% showed detectable levels of organic acids.     

高效液相色谱法测定柑橘汁中类胡萝卜素

用正己烷、丙酮、乙醇混合溶剂提取宽皮柑橘大叶尾张中类胡萝卜素,10%KOH的甲醇溶液皂化12h,比较了hypersilODS2和YMCC30两种不同的色谱柱的分离效果。结果表明C30色谱柱分离效果优于hypersilODS2色谱柱。通过类胡萝卜素典型的特征吸收峰,结合在线的PAD检测器,初步判断在C30色谱柱分离的类胡萝卜素有18种。     

Effect of Oxygen on Taste, Ascorbic Acid Loss and Browning for HTST-Pasteurized, Single-Strength Orange Juice

Single-strength orange juice with dissolved oxygen levels of 0.6, 1.8, 6.5, and 10.1 ppm was pasteurized at 85°C for 7 sec using a pilot-scale, high temperature-short time, tubular, heat exchanger. The product was aseptically bottled under nitrogen and stored for 5 months at 22°C. Browning and loss of ascorbic acid were linearly related to the initial oxygen concentration. Based on the results of sensory evaluation, reducing the initial dissolved oxygen concentration by 94% did not extend the shelf-life of single-strength orange juice. Therefore, based on taste, deaeration will not extend the shelf-life of this product.