卷式反渗透膜浓缩番茄汁的实验研究

介绍了采用卷式反渗透膜浓缩番茄汁的工艺,研究了工艺中的温度、压力、流速、浓度与膜通量的关系。同时也研究了卷式反渗透膜在浓缩过程中对有效成分的截留率,实验证明膜对有效成分的截留率大于98%,清洗方便。      

浓缩和酸化对番茄汁质量的影响

本文研究了不同热破碎温度和时间对番茄汁粘度的影响，及浓缩过程中番茄汁色泽和粘度的变化，给出了浓缩时间、浓缩番茄汁的可溶性固形物含量和浓缩番茄汁的ａ／ｂ值间的回归方程；并探讨了酸化保存番茄汁的可能性。     

卷式膜超滤浓缩猪血浆工艺研究

以猪血浆液为研究对象,比较截留分子量（MWCO）为20000D、10000D和5000D的卷式超滤膜对血浆浓缩效果的影响,研究超滤血浆过程中,超滤压力、超滤温度、血浆蛋白浓度、pH值和时间对超滤膜效果的影响。结果表明,MWCO=5000D膜更适合用于超滤浓缩血浆液,超滤压力和蛋白浓度对通量影响更加显著。综合考虑猪血浆蛋白加工实际情况,获得最佳工艺条件为：在1．5MPa压力下,将分离血浆液（pH值7．0—7．5、蛋白浓度7．5％～8．0％、温度13～15℃）,连续超滤40min。     

管式反渗透浓缩牛奶的实验研究

介绍了采用管式反渗透膜浓缩牛奶的工艺,研究了工艺中的压力、温度、浓度和浓缩过程与牛奶中有效成分的截留率之间的关系,同时也研究了压力、温度、浓度在浓缩过程中与膜通量之间的关系。实验结果证明,管式反渗透膜对有效成分的截留率接近100%。     

采用正渗透技术浓缩番茄汁

采用正渗透技术浓缩了番茄汁,研究了不同温度下,NaCl汲取液浓度对番茄汁浓缩速率的影响。实验结果表明:渗透速率随着温度升高而加快,当温度超过一定值时,渗透速率反而降低,随着NaCl溶液浓度的升高,渗透速率增加,浓缩时间大大缩短,最后浓缩番茄汁糖度可达到32°Brix。     

蛤肉预煮液反渗透膜浓缩工艺研究

以蛤肉预煮液为原料,经非热力浓缩--反渗透膜(RO膜)处理达到理想料液浓缩度.通过选择RO膜种类以及对操作压力、操作温度和进料流速三因素的L9(34)正交试验,确定二级反渗透浓缩的最佳工艺条件.结果表明:选用三醋酸纤维素RO膜效果最好;二级RO膜浓缩的最佳工艺条件为压力3.5 MPa、温度38℃、流速1.5 m/s;浓缩后料液浓缩度可达32.5°Bx.     

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。     

香菇多糖反渗透浓缩工艺的研究

采用反渗透膜浓缩工艺对香菇多糖提取液进行浓缩,分析进膜压力、料液浓度和进膜温度对浓缩工艺的影响,并比较了反渗透浓缩和真空浓缩两种方法的差异.结果表明,在进膜压力20 MPa、多糖浓度6.48 mg/mL、进膜温度30℃时能取得较好的浓缩效果.反渗透膜浓缩粗多糖得率较真空浓缩高,且DPPH自由基清除能力优于真空浓缩的产品...     

反渗透浓缩籽瓜汁的实验研究

采用反渗透技术对籽瓜汁进行浓缩,分别研究了膜通量、压力、料液温度、籽瓜汁浓度等参数之间的关系,结果表明:反渗透膜对籽瓜汁有效成分的截留率接近100%,对无机盐截留率大于98%,籽瓜汁的最终浓缩浓度为20Brix;其它条件不变的情况下,膜通量与压力、料液温度成正比关系,与料液浓度成反比关系。      

Application of osmotic membrane distillation process in red grape juice concentration

The osmotic membrane distillation process was applied in dehydration of red grape juice (Most de Raïm Concentrat Negre) of different concentrations (5–20 °Brix). Experiments were performed using polytetrafluoroethylene (PTFE) hydrophobic membranes of different nominal pore diameter. Red grape juice solution and concentrated calcium chloride solution (50 wt.%) were used as feed and stripping solutions, respectively. The permeate flux, the initial and the final juice concentration, the total phenolic content (TPC) and the antioxidant activity (TEAC) were measured for each single experiment.     

Coupling reverse osmosis and osmotic distillation for clarified pomegranate juice concentration: Use of plasma modified reverse osmosis membranes for improved performance

In this study, a low pressure nitrogen plasma (LPNP) activation was implemented to modify the surface characteristics of a commercial thin film composite (TFC) polyamide reverse osmosis (RO) membrane. The free energy of interaction (ΔG_iwi) results showed that the hydrophobic nature of untreated TFC RO membrane became considerably hydrophilic with the effect of LPNP treatment. Among various plasma powers and exposure times tested, a general decreasing trend was observed for the water contact angle with increasing plasma duration, reaching a minimum of 13.2 ± 0.8° for 90 W at 15 min. A remarkable increase in water flux of the LPNP modified RO membrane was observed throughout the RO process, which promoted higher soluble solids content (SSC) values in the concentrated juice at the same period of time with the plain one. The higher SSC values achieved by the modified RO membrane enabled 30% time-saving during further osmotic distillation process.     

High concentration of skim milk proteins by ultrafiltration: Characterisation of a dynamic membrane system with a rotating membrane in comparison with a spiral wound membrane

The purpose of this work was to characterise the ultrafiltration of skim milk with a dynamic system with a rotating membrane regarding flux in milk protein concentration. The flux of the dynamic system showed a maximum at medium rotational speeds, probably due to the permeate backpressure or a shift in the deposited particle size range to smaller particles above a critical rotational speed. The flux increased almost linearly up to a transmembrane pressure (TMP) of 100 kPa. At higher TMP, the curves levelled off, especially at higher protein concentrations. The dynamic system was less limited by the increasing retentate viscosity and reached significantly higher volume reduction ratios (VRR) as compared with a spiral wound module (SWM). SWM are suitable to achieve VRR <5–6 before a dynamic system, possibly in combination with tubular ceramic membranes, could be used to achieve higher VRR >8.     

果汁和蔬菜汁的分离澄清新技术

<正> 人们对于天然食品的需求不断增加。就天然果汁的消费而言,苹果浊汁一直是需求强劲的产品。苹果浊汁的主要特点是色泽较淡,并具有较稳定的混浊度。采用带式压滤系统、加热系统和离心系统,可保持这些特性。本文将介绍压榨过滤新技术在果汁及蔬菜汁中的应用。     

果胶酶提高番茄出汁率的工艺研究

通过单因素和正交试验确定果胶酶提高番茄出汁率的最佳工艺条件,结果表明,果胶酶的添加量为0．18％,酶解时间为90min,酶解温度为50℃时番茄的出汁率最高,为75．5％,与未经果胶酶处理的番茄相比,出汁率可以提高19．7％。     

Clarification and concentration of melon juice using membrane processes

Melon juice obtained from fruits discarded by exporters was first clarified by crossflow microfiltration and then concentrated by osmotic evaporation (OE). The resulting clarified melon juice was highly similar to the initial juice, except for insoluble solids and carotenoids, which were concentrated in the retentate. Average permeation flux was relatively high (about 80 L h⁻¹ m⁻²), with continuous extraction of retentate at a volumetric reduction ratio of 3. After concentration of the clarified melon juice to as much as 550 g kg⁻¹ of total soluble solids using a continuous feed-and-bleed procedure of OE, we found that almost the entire composition of the product was preserved. This integrated membrane process permitted two valuable products to be obtained: a clarified concentrate of melon juice that had not undergone any thermal treatment, and a glowing-orange retentate that was enriched in provitamin A.Industrial relevanceThe increasing quality demand for fresh fruits results in an increase in rejected melons. Juice processing could overcome the product losses occurring but thermal sensitivity of melon juice flavour prohibits conventional thermal processing. Interestingly this paper attempts to use membrane processes for microbial stabilisation and concentration. The authors present a novel way of using permeate (clear juice) as well as retentate (pulpy juice). Enzyme activities in the products during and after processing may need some attention prior to industrial application of the process.     

Recovery and concentration of phenolic compounds in blood orange juice by membrane operations

Cross-flow ultrafiltration (UF) and osmotic distillation (OD) were implemented on laboratory scale to obtain formulations of interest for food and/or pharmaceutical industry starting from the blood orange juice produced in the Calabria region. The freshly squeezed juice, after a depectinization step, was submitted to an UF process in order to recover natural antioxidants, such as hydroxycinnamic acids, hydroxybenzoic acids, flavanones, flavan-3-ols, and anthocyanins. The UF permeate, with an initial total soluble solids (TSS) content of 10.5°Brix, was concentrated by OD up to a final concentration of 61.4°Brix.     

Circulation cleaning of a plate heat exchanger fouled by tomato juice

A diluted tomato paste, applied as evenly as possible to one side of plate heat exchanger plates, has been used to study the effect of three temperatures (20, 70 and 90°C) when using water as a circulation cleaning fluid. From the experimental results it would appear that 70°C is the optimum temperature for this duty. Increasing the temperature to 90°C caused protein denaturation of the deposited tomato soil and cleaning efficiency was reduced. The soiling technique used in this work was found to be simple and consistent in studying the cleaning-in-place of the plate heat exchanger, and the direct weighing method of measuring soil removal was found to be reproducible.     

A description of a flat geometry direct osmotic concentrator to concentrate tomato juice at ambient temperature and low pressure

A novel membrane module was developed for the purpose of concentrating tomato juice by direct osmosis at ambient temperature and low pressure. This stainless steel module was in the shape of a flat configuration consisting of two parts of a square flange screwed together, with a piece of flat membrane between them. The configuration resulted in the formation of two chambers of special morphology which allowed the flow of tomato juice and osmotic medium in the two respective sides of the membrane and enabled the osmotic transfer of pure water from the juice to the osmotic medium side.