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。     

柑桔汁反渗透浓缩的研究

对超滤分离后的柑桔汁进行反渗透浓缩研究。实验找到了适合柑桔汁浓缩的反渗透膜RO-1,同时确定反渗透浓缩的适宜工作条件为:p=4.5MPa,T=40,S=1m/s,柑桔汁可浓缩到23°Bx。分别用0.1%NaOH和0.5%U10溶液清洗反渗透膜,其膜通量能完全恢复。通过分析比较柑桔原汁和浓缩汁的营养成分得出结论:膜分离技术浓缩柑桔汁切实可行。     

Passion Fruit Juice Concentration by Ultrafiltration and Evaporation

Passion fruit juice was pretreated with pectinase, centrifugation, and pasteurization. The resulting juice was processed by Ultrafiltration (UF) to 20°Brix. The UF permeate was concentrated by evaporation to 70°Brix and combined with the UF retentate to form the final concentrated product at 40°Brix. The pretreatments caused approximately 20% flavor losses, but accomplished more than 50% flux increases. The UF recovered many important flavor constituents, and improved the rate of evaporation. The final concentrated product contained more than 30% of juice flavor. Results of sensory evaluation indicated that flavor of the reconstituted juice was inferior to fresh juice, but the two juices were not significantly different in overall acceptance.     

Flavor Losses in Orange Juice during Ultrafiltration and Subsequent Evaporation

Losses of volatile compounds in orange juice during ultrafiltration and subsequent evaporation were studied. Alcohols and esters predominated in the permeate, while terpenes (d-limonene and valencene) and nonpolar aldehydes (octanal and decanal) were distributed in the retentate from the ultrafiltration (UF) system. Fractions of some flavor compounds were lost during ultrafiltration process. An aqueous phase essence was recovered from the permeate during evaporative concentration. No oil phase was observed. When whole juice was concentrated, both oil and aqueous phases were recovered. Essence recovery efficiency of individual compounds was 3 to 13% when concentrating permeate and <5% when concentrating whole juice.     

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.     

柑桔汁超滤传质过程机理的研究

以"凝胶层阻力"及"渗透压阻力"理论为基础,根据柑桔汁在超滤过程中的通量变化规律,求出柑桔汁超滤过程的传质方程式,同时研究了操作压力对膜通量的影响,分析了造成传质阻力的主要因素,探讨了柑桔汁超滤过程的传质机理.     

赣南脐橙橙汁浓度的快速测定

采用紫外分光光度法对赣南脐橙橙汁浓度进行快速测定,结果表明,赣南脐橙橙汁含量不同的样品有不同的紫外吸收曲线;在273 nm下有特征吸收峰;橙汁浓度在0~5%范围内,相关性良好,y=1.738 7ln(x)+2.518,相关系数为0.963 8。     

Flow Properties of Low-Pulp Concentrated Orange Juice: Effect of Temperature and Concentration

Three 65° Brix low-pulp concentrated orange juice (COJ) samples, between −19 and 30°C were shear-thinning (pseudoplastic) fluids with negligible magnitudes of yield stress. The simple power law model fit welt the shear rate-shear stress data. For one sample, the Powell-Eyring model also described the data well. The Arrhenius model described the effect of temperature on the apparent viscosity and the consistency index of the power law model. The activation energy of flow (E_a) was 10.7 ± 0.2 kcal/g mole. The models of Harper and El Sahrigi and Christiansen and Craig were suitable for describing the combined effect of temperature and shear rate. The magnitude of E_a decreased with decrease in concentration. Apparent viscosity and K increased exponeitially with concentration.     

Stabilization of Anthocyanins of Blood Orange Fruit Juice

The stability of the red color of pigmented orange fruit juice was somewhat improved by pasteurization with microwaves and addition of tartaric acid and gluthathione as mildly acidic and antioxidant agents, respectively. Highest stability was obtained through the formation of complexes between anthocyanins and phenolic compounds, such as rutin and caffeic acid.     

血橙果汁贮藏过程中品质变化研究

通过血橙原汁成分分析,对血橙原汁低温贮藏过程中与品质相关的几项指标的变化进行监测,以探讨低温贮藏对血橙果汁品质的影响。结果表明：血橙汁富含花色苷(68.84mg/L)、黄酮类物质(0.18mg/mL)、抗坏血酸(0.63mg/mL)、氨基酸(43.012mg/mL)、糖类(128.3mg/mL)等物质,还含有Ca、Mg、Zn、Fe、Cu 等丰富的人体必需微量元素;同时HPLC 分析显示血橙汁含有的可溶性糖主要是蔗糖(7.4g/100mL)、果糖(2.2g/100mL)、葡萄糖(2.1g/100mL)。在血橙汁贮藏过程中,随着花色苷含量的下降橙汁鲜艳的红色也逐渐褪色成浅黄褐色,抗坏血酸含量明显下降,贮藏40d 后含量下降约52%;而还原糖含量变化缓慢,总酸含量平缓增加。     

Influence of Carotenoids and Pulps on the Color Modification of Blood Orange Juice

The causes of color modification in blood orange juice due to the heating concentration process were investigated. A Not From Concentrate (NFC) juice and a Reconstituted From Concentrated (RFC) juice, arising from the same stock of pigmented oranges, appeared very different in color although they had the same content of anthocyanins. CIE (Commision Internationale des Enclarages)-Lab measurements showed a slight decrease of L* and a* values and a very large increase of b* and hue values in RFC juice. Different distribution of carotenoids between serum and pulps and modification of pulp size appeared to be responsible for color modification.     

Quality of Retail Florida-Packed Frozen Concentrated Orange Juice as Determined by Consumers and Physical and Chemical Analyses

Six commercial Florida-packed frozen concentrated orange juice samples drawn from the U.S. retail market on a monthly basis for 1 yr were evaluated for sensory attributes, color (by colorimeter), Brix, acid, and bottom pulp. Consumers rated flavor “like moderately” on a 9-point hedonic scale for every sample. The degree of sweetness and tartness of samples was “just right;” bitterness was somewhat excessive and color was somewhat too light (P < 0.05). Generally, as the °Brix to % acid ratio increased, the flavor improved, and the closer to “just right” was the degree of sweetness, tartness, and bitterness. A significant amount of bitterness was perceived as tartness or lack of sweetness (P < 0.01). Plant-to-plant variation was found in ratings of flavor and colorimeter color and °Brix to % acid ratios.     

高压微射流技术对红枣汁理化性质的影响

以红枣汁为研究对象,研究高压微射流对红枣汁理化性质的影响。将红枣汁分别采用不同压力（40、80、120、160、200 MPa）和不同处理次数（1、2、3、4 次）处理,分析高压微射流处理对红枣汁的ζ电位、平均粒径、色差、透光率、非酶褐变程度和可溶性固形物含量的影响。结果表明：在不同压力条件下的红枣汁的平均粒径、可溶性固形物、澄清度、非酶褐变程度和色差值有显著性差异（P＜0.05）,160 MPa条件下处理4 次的红枣汁平均粒径最小,是对照组平均粒径的16.8%;160 MPa条件下处理2 次的红枣汁透光率达到最佳,为77.6%;120 MPa条件下处理4 次的红枣汁可溶性固形物含量达到最高,较对照组增加了29.6%;160 MPa条件下处理1 次的红枣汁非酶褐变程度最低,与对照组之间差异性不显著性（P＞0.05）,160 MPa条件下处理1 次的红枣汁色差值L*最大。不同处理次数的红枣汁之间的电位有显著性差异（P＜0.05）。表明高压微射流可以改善红枣汁的理化性质,能够为消费者提供高质量的果汁。     

加工单元操作对血橙汁香气成分的影响

以塔罗科血橙汁为研究对象,对手榨汁、精滤汁、杀菌汁和还原汁采用顶空固相微萃取-气相色谱-质谱联用法测定了橙汁香气成分。结果表明,4 种血橙汁分别检出47、55、51 种和14 种香气成分,总含量分别为459.21、1 436.16、1 194.25、118.72 mg/kg,精滤汁比手榨汁多检出莰烯、丁酸甲酯、壬醇、癸醛等物质,杀菌后果汁多检出壬醛,压榨过滤和加热有助于香气的形成,但要控制副作用物质如α-松油醇等的增加,浓缩还原后橙汁香气最差,在生产中可利用回填方式提高产品品质。     

鲜榨锦橙汁香气成分的固相微萃取-气质联用分析

采用固相微萃取-气质联用法对鲜榨锦橙汁的香气成分进行分析,并比较不同萃取头对鲜榨橙汁香气成分的萃取差异。结果表明:从鲜榨橙汁中共鉴定出53种香气成分,包括烯烃类、酯类、醇类、醛类和酮类,其中的主要香气化合物为柠檬烯、β-月桂烯、芳樟醇、α-松油醇、4-松油烯醇、丁酸乙酯、辛醛、α-蒎烯、β-水芹烯等物质。     

Preparation and Chemical Composition of Orange Oil Concentrates

Flavor and color concentrates were prepared by a vacuum distillation process from cold pressed Valencia and midseason orange oils and were analyzed quantitatively by gas chromatography. Twenty-five major and minor constituents were identified by mass spectrometry. The influence of the concentration process on oxygenated flavor compounds, primarily aldehydes and alcohols, was evaluated. Aldehydes and color values were determined by chemical and spectrophotometric methods. When compared with midseason orange oils, 25–35% higher concentration of oxygenated flavor compounds and of total aldehydes were found in Valencia orange oils. Midseason oils had 20–30% higher color values when compared with Valencia oils. Cold pressed oils concentrated to 25-fold had an increase in color value of 20-fold, while the concentration of oxygenated flavor compounds increased about 10 times.     

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).