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.     

柑桔汁脱苦方法研究进展

对柑桔汁形成苦味的原因及目前柑桔汁脱苦方法的研究进展进行了综述,并提出了今后的研究方向。      

柑桔汁脱苦方法研究进展

对柑桔汁形成苦味的原因及目前柑桔汁脱苦方法的研究进展进行了综述,并提出了今后的研究方向。     

微生物与柑桔汁脱苦

对用于柑桔汁脱苦的微生物种类及其脱苦机理进行了综述,同时介绍了与脱苦有关的酶及微生物细胞的固定化在柑桔汁脱苦中的应用。     

天然亲水性胶体对甜玉米混汁悬浮稳定性的影响

研究不同天然亲水性胶体及其不同添加量对鲜嫩甜玉米混汁稳定性的影响。采用响应面法,将不同胶体按照设计添加量添加到玉米汁中,通过测定离心前后的吸光度得出稳定系数,以此判断甜玉米混汁的悬浮稳定性。结果表明：结合单因素试验和响应面法分析得出的最佳复配结果为瓜尔豆胶0.07%、亚麻籽胶0.07%、黄原胶0.07%,此时的稳定系数为87.91%。     

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。     

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。     

Cloud Stabilization of Orange Juice by High Pressure Processing

High pressure processing (HPP) was investigated as a means to preserve cloud in freshly squeezed orange juice. Cloud loss is a major quality defect in orange juice, and methods of preserving cloud without the extreme temperatures used in commercial pasteurization are desirable. Pressures from 500 to 900 MPa were investigated at dwell times of 1 sec, 1 min and 10 min. Higher pressures and longer processing times were more effective at preserving cloud, while all treatments yielded a microbially stable product. A 90-day shelf life under refrigeration conditions could be achieved using pressures of 700 MPa and higher combined with treatment times of 1 min.     

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.     

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.     

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.     

几种常用食品添加剂对橙汁饮料中V_C稳定性的影响

在一定的光、温度、O2和pH条件下,食品中常用的防腐剂、增稠剂、抗氧化剂、营养强化剂对VC稳定性有一定的影响。其中,山梨酸钾、EDTA-Na2、果胶、L-赖氨酸盐酸盐这4种常用的食品添加剂均对VC有一定稳定作用;而且同时使用这4种添加剂时,其稳定作用更显著,能明显降低VC-1%HCl溶液、橙汁模拟体系和鲜橙汁中VC的损失率。通过试验,发现其最佳组合是0.5g/kg的山梨酸钾、1.5g/kg的EDTA-Na2、1.5g/kg的果胶、0.5g/kg的L-赖氨酸盐酸盐。     

桔汁酿酒可行性研究

对以无核桔为原料生产桔子酒的可行性进行了研究。探讨了温度、时间、接种量等因素对酒体品质及风味的影响,并通过感官评定得出桔子酒的最佳生产工艺。结果表明：采用压榨取汁,主酵温度 23℃、酵母接种量 2× 106cfu/mL、主酵时间 5d、后酵温度 10℃、时间为 21d,所酿制的桔子酒果香浓郁、风味独特。     

橙汁饮料感官评定研究

用模糊数学法对三种橙汁饮料进行了感官评定,结果表明,206样品的评定级别为很好与好之间,561和392样品的评定级别为很好,但392比561稍好,三种橙汁饮料的评定级别从高到低依次为392﹥561﹥206。