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.     

Facilitation of cleaning of alumina surfaces fouled with heat-treated bovine serum albumin by ozone treatment

Facilitation of cleaning of alumina (A12O3) particles fouled with heat-treated bovine serum albumin (BSA), which contains sulfhydryl groups on the molecule, by gaseous ozone was studied. With increasing temperature of heat treatment, the amount of adsorbed BSA onto A12O3 surfaces increased, whereas the rate of BSA desorption during alkali cleaning decreased markedly, resulting in the larger amounts of BSA remaining on 12O3 surfaces. No significant amounts of BSA were removed from A12O3 surfaces by alkali cleaning alone when treated at temperatures above 120 degrees C. Before alkali cleaning, the heat-treated, BSA-fouled AI2O3 at 150 degrees C were treated with 0.05 to 0.30% (vol/vol) gaseous ozone at room temperature. Ozone pretreatment markedly accelerated the rate of BSA desorption during subsequent alkali cleaning. The effect of ozone pretreatment on BSA removal depended on the concentration of ozone and treatment time and hence on the total amount of ozone supplied. The molecular weight (MW) of desorbed BSA during alkali cleaning without ozone pretreatment coincided with the MW of the native BSA, whereas the MW of desorbed BSA during the combined ozone-alkali cleaning was lower than the MW of the native BSA. This indicated that the heat-treated BSA molecules adsorbed on A12O3 were partially decomposed into some fragments by ozone pretreatment, resulting in the facilitation of the removal of BSA during alkali cleaning.     

固定化乳酸菌发酵番茄饮料工艺研究

以番茄汁为主要原料,研究了用海藻酸钠包埋乳酸菌发酵番茄饮料的最佳工艺.研究结果表明,固定化乳酸菌发酵番茄饮料的最佳工艺条件为:海藻酸钠溶液浓度为1.5%,胶珠直径2～3mm;接种量6%,发酵温度33℃,番茄汁初始pH5.0,发酵时间36h,接着添加7%白砂糖、0.005%黄原胶和0.02%CMC-Na,以使感官指标达到最佳.连续发酵结果表明,固定化乳酸菌发酵番茄饮料可连续使用7次.     

Viscoelastic properties of tomato juice

Tomato is one of the most important vegetables for the food industry. Rheological characterization of tomato products is important for products, equipments and unit operations design and evaluation. It is necessary for process optimization and high quality products assurance. However, the works in literature present variable data, and some rheological characterization, as viscoelastic properties are still scarce. The present work has evaluated the viscoelastic properties of tomato juice, as well as the applicability of the Cox-Merz rule. The obtained data are potentially useful for future studies on food properties and process design.     

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。     

Carbon nanotube-polytetrafluoroethylene nanocomposite coating for milk fouling reduction in plate heat exchanger

Cleaning of milk fouling on plate heat exchanger surface causes intermittent downtime to milk processing industry. Fouling occurrence during milk pasteurization potentially reduces the heat transfer rate of plate heat exchanger (PHE), leading to serious energy deficiency. In this study, the development of milk surface foulant was successfully inhibited by superhydrophobic nanoparticulate coating of PHE surfaces. Full dispersion of multiwalled carbon nanotubes (MWCNTs) in hydrophobic polytetrafluoroethylene (PTFE) matrix was completed using ultrasonication and high temperature annealing techniques. Nanomorphology and surface structure of PTFE and CNT-PTFE films on stainless steel surface were interpreted by field emission scanning electron microscope (FESEM). To validate the hydrophobicity of the developed CNT-PTFE nanocomposite coated surface, a water contact angle (WCA) using a simplified sessile drop method, correspondent surface energy, foulant mass, and energy efficiency after milk pasteurization were estimated and compared with stainless steel 316 and polytetrafluoroethylene (PTFE) coated surfaces. Static contact angles for the control, PTFE-coated and CNT-PTFE surfaces increased from 71.2 to 119.6 and 141.1°, respectively. By application of CNT-PTFE nanocomposite coating, the estimated surface energy of heat exchanger surface decreased by 97.0% of its original value. After continuous milk pasteurization for 5 h, the mass of foulant on CNT-PTFE coated heat exchanger surface was 70.3% less than that of the uncoated surface; thus, total energy consumption of test PHE unit also dropped down by 10.2%. Developed CNT-PTFE nanocomposite coated surface will potentially reduce the risk of under-processed milk and decrease the frequency of the routine cleaning-in-place (CIP) program.     

Antioxidant properties of tomato juice as affected by heating

The changes in the overall antioxidant properties of tomato juice samples and model solutions as a consequence of heat treatments were studied. The antioxidant properties were evaluated both through the measurement of the chain breaking and the oxygen scavenging activities. While a decrease in the antioxidant potential was found for short heat treatments, a recovery of these properties was measured by prolonging heating times. Results suggested that the initial reduction in the overall antioxidant activity can be attributed not only to the thermal degradation of naturally occurring antioxidants but also to the formation of early Maillard reaction products (MRP) with pro‐oxidant properties. The gain in antioxidant activity coincided with the formation of brown MRP. © 1999 Society of Chemical Industry     

Degradation kinetics of tomato juice quality parameters by ozonation

Tomato juice samples were ozonated with control variables of ozone concentration (1.6–7.8 %w/w) and treatment time (0–10 min). Effects of ozone processing variables on quality parameters of pH, ^oBrix, titratable acidity (TA), cloud value, non-enzymatic browning, colour values ( L *, a *, and b *) and ascorbic acid (AA) content were determined. No significant changes ( P  > 0.05) in pH, ^oBrix, TA, cloud value and Non enzymatic browning (NEB) ( P  ≤ 0.05) were found with ozonation. L *, a * and b * colour values were significantly affected by ozone concentration and treatment time. A significant reduction of AA (96 %) was observed at an ozone concentration of 7.8%w/w and a treatment time of 10 min. Results presented in this study indicate that visual colour and nutritional quality is significantly affected during ozone processing. Thus, the effects of ozonation on the nutritional properties of tomato juice should be considered by processors prior to its adoption as a preservation technique.     

新型底锥型螺旋板式热交换器特点简介

节能清淤是每一个方便面生产厂家最关注的问题。入世以后，特别是２００１年下半年以来，方便面制造业无论产量、品质都有了明显的提高和发展。据统计２００１年方便面生产产值达到２６０亿，是历年来最高峰。如此大的行业其能源消耗和油炸介质（棕榈油）的洁净问题成为大家最关注的敏感点，新型底锥型螺旋板热交换器就是为同时改善上述两个问题的工作状况而专门设计的。特点一采用整板卷制、无中心隔板焊缝工艺，解决了传统工艺换热器容易泄漏的问题。其结构决定了换热介质与物料全逆流的交换途径，大大提高了换热效率。特点二传统螺旋板式…     

饮料灭菌设备--板式换热器成套系统的设计与选用

从实际设计者与使用者的角度，结合实例阐述简单实用的换热器设计方法及过程，通过了解设计者的意图，合理地选用设备。     

番茄汁酸奶的研制

用保加利亚乳杆菌（L.bulgaricus）与嗜热链球菌（S.thermophilus）按1：1比例混合作发酵剂，用新鲜优质牛乳为原料，加入0.2%-0.3%的稳定剂，经90-95℃加热处理5min，冷却至45℃左右，加入经杀菌后的新鲜蕃茄汁8%，按2%-3%比例加入发酵剂，装瓶于39-43℃培养2-2.5h，冷藏可制得风味纯正，营养价值高的酸奶。     

Clarification of tomato juice by cross‐flow microfiltration

Clarification of fruit and vegetable juice is one of the integrated parts of modern industrial juice processing. This paper describes the clarification of tomato juice through microfiltration process. In this regard, the influence of transmembrane pressure (1, 2 and 3 bar), cross‐flow velocity which corresponds with Reynolds number (300, 1500 and 2500) and temperature (30, 40 and 50 °C) on permeate flux and some properties of clarified juice such as colour, turbidity, density, viscosity, pH and total soluble solid have been studied. The results revealed that the investigated parameters had an increasing effect on the permeate flux and colour and the greatest effect on the permeate flux and colour was supplied by cross‐flow velocity. The other permeate properties did not significantly change with variations of the operating parameters. Eventually, the statistical analysis indicated that the interactional effect of cross‐flow velocity and TMP on the permeate flux was significant.     

Effect of ozone pretreatment on alkali cleaning of alumina fouled with bovine serum albumin

Pretreatment of alumina particles fouled with bovine serum albumin (BSA) by 0.3% (v/v) gaseous ozone markedly accelerated the removal of BSA during alkali cleaning through partial decomposition of the BSA molecule. The results suggest that ozone pretreatment can reduce the NaOH concentration required for adequate alkali cleaning by at least one order of magnitude.     

Preservation of tomato juice under acid conditions

A technique for preserving tomato juice and crushed tomatoes under acid conditions has been developed. This eliminates the need for the usual processing time of 55 min in boiling water for 650 ml glass bottles, which would result in considerable savings in energy requirements by the tomato processing industry. The ketchup prepared from the acidified tomato juice and crushed tomatoes (after neutralisation) was rated by the panelists to be as good as a commercial tomato ketchup sample.     

The sorption of aroma components from tomato juice by food-contact polymers

The sorption of some aroma components from tomato juice by polyethylene terephthalate (PET) was shown to be less than the sorption of the same components by polyethylene (PE) and wet ethylene/vinylalcohol copolymer (EvOH) polymers. Furthermore, sorption by PET was less influenced by pH than sorption by the PE and EvOH polymers. The amounts of aroma compounds extracted from the polymers varied with type of polymer, type of aroma compound, pH and time of storage.     

Comparative study on color,viscosity and related enzymes of tomato juice treated by high-intensity pulsed electric fields or heat

The effects of high intensity pulsed electric fields (HIPEF) processing (35 kV/cm for 1,500 μs using bipolar 4-μs pulses at 100 Hz) on color parameters and viscosity, as well as peroxidase (POD), pectin methylesterase (PME) and polygalacturonase (PG), were evaluated during 77 days of storage at 4 °C and compared to thermal treatments at 90 °C for 1 min or 30 s for unprocessed tomato juice. HIPEF-treated tomato juice showed higher values of lightness than the thermally processed and the untreated juice throughout storage time (P < 0.05). Viscosity of HIPEF-treated tomato juice was also greater than both thermally treated and untreated for the first 35 days of storage. POD of HIPEF-treated tomato juice was inactivated by 97% whereas in the case of the thermally treated, 90 and 79% inactivation was achieved after 1 min and 30 s, respectively. The highest PME inactivation in tomato juice was obtained by PEF (82%) and heat treatment at 90 °C for 1 min (96%). PG of PEF-treated tomato juice was inactivated by 12% whereas thermal treatments at 90 °C for 1 min or 30 s achieved 44 and 22%, respectively. Despite the low rates of PG inactivation obtained, the pattern followed in the residual activity along the storage time was similar in the tomato juice treated by HIPEF than the thermally processed.     

Physicochemical parameters that influence carotenoids bioaccessibility from a tomato juice

In vitro digestion models have been developed to estimate carotenoid bioavailability but most do not consider that their diffusion from fruit matrix to the lipid phase of the bolus could be a limiting step. Therefore we designed a model in which tomato juice is mixed with oil or oil/water emulsions, and the carotenoids diffusing to oil are measured by spectrometry. Temperature, pH and tomato juice/peanut oil ratio were evaluated for their influence on carotenoid diffusion. When oil/tomato ratio was between 0.11 and 1, extraction of lycopene was limited by the saturation of the oil phase. With a large excess of oil, diffusion was also limited, as only 31 ± 1% of lycopene could be extracted from the juice. Diffusion did not vary significantly with pH but doubled when temperature rose from 10 °C to 37 °C.     

西瓜番茄胡萝卜汁的研制

西瓜、番茄、胡萝卜营养丰富,具有一定的保健功能。通过实验确定了西瓜番茄胡萝卜汁的最佳配方,并对稳定剂、杀菌条件及生产环境进行了探讨。     

芹菜、番茄、胡萝卜复合蔬菜汁的研制

研究了芹菜汁、番茄汁、胡萝卜汁的提取方法。通过正交试验确定生产复合蔬菜汁的最佳配方,并较好地解决了蔬菜汁的沉淀及特有风味的保留等问题。