Clarification of Pear Juice by Hollow Fiber Ultrafiltration

Hollow fiber ultrafiltration was successfully applied to obtain a clear, amber-colored pear juice. For the three hollow fiber membrane cartridges tested (50,000, 30,000, and 10,000 dalton molecular weight cut-off), the process parameters were optimized and found to be similar. The permeate flux increased with increased transmembrane pressure and then declined. Flux reached a maximum at an average transmembrane pressure of 157 kPa with an average feed stream velocity of 0.15 meters/set at 50°C. Higher flux was obtained at higher temperatures within the temperature limitations of the membrane. Flux decreased linearly with the logarithm of the concentration.     

Optimization of Apple Juice Production by Single Pass Metallic Membrane Ultrafiltration

Apple puree was treated with various amounts of commercial liquefaction enzyme (0%– 0.066%) for 2 hr at 50°C. To produce clarified juice purees were pumped through a metallic oxide membrane ultrafiltration system, consisting of 3.27 ft² (0.304 m²) of membrane coated internally onto a l–1/4 inch (i.d.) × 10 ft (3.12 cm × 3.04 m) sintered stainless steel tubing. All enzyme treatments reduced viscosity 70–80% within 1 hr but steady state flux increased with higher concentrations of enzyme. Alcohol insoluble solids (AIS) and total pectins of the apple puree after enzyme treatment decreased as enzyme concentration increased to 0.044%. A large scale system, l–1/4 inch (i.d.) × 120 ft (3.12 cm × 36.48 m), was operated at 86% juice yield with minimal pressure drops as predicted by a mathematical model.     

EFFECT of pH and ENZYMATIC TREATMENT ON MICROFILTRATION and ULTRAFILTRATION of TANGERINE JUICE

Tangerine (Citrus reticulata blanco) juice clarification by crossflow microfiltration and ultrafiltration using polysulphone flat sheet membranes with nominal molecular weight cut off of 25,000, 50,000, 100,000 and 0.1 μm, 0.2 μm pore sizes was studied. the juice was pretreated by polygalacturonase and pH adjustment. the treated juice was clarified with a laboratory scale filtration unit with effective filtration area of 14 cm². Filtration conditions were transmembrane pressure of 93 to 194 kPa, crossflow velocity of 0.96 to 3.5 m/s and 25°C. Membrane performance was evaluated in terms of volume flux and clarity (% transmittance) of the permeate. Pretreatment of the juice by polygalacturonase and adjustment to pH 2 with HCl resulted in a clearer supernatant than enzyme treatment alone. Maximum flux was obtained with the 0.1 μm microfiltration membrane. Flux increased with transmembrane pressure and crossflow velocity. Flux at 194 kPa and 3.5 m/s was 69 L per square meter per hour. Permeate clarity was better at higher transmembrane pressure and lower velocity, due to the effect of the polarized/fouling layer of solute on the membrane surface, which acted as a secondary “dynamic” filter.     

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.     

Possible nutritional and health‐related value promotion in orange juice preserved by high‐pressure treatment

Effects of high‐pressure treatment on the orange juice carotenoids (β‐carotene, α‐carotene, zeaxanthin, lutein and β‐cryptoxanthin) associated with nutritional (vitamin A) and health‐related (radical‐scavenging capacity) values were investigated. Various high‐pressure treatments (50–350 MPa) combined with different temperatures (30 and 60 °C) and times (2.5, 5 and 15 min) of treatment were assayed. The carotenoid content of the orange juice was analysed by HPLC‐UV, the vitamin A value was determined as retinol equivalents (RE) and the free radical‐scavenging capacity was evaluated using the DPPH (2,2‐diphenyl‐1,1‐picrylhydrazyl) radical model system. A storage study was carried out at refrigeration temperature (4 °C). High‐pressure treatments at 350 MPa produced significant increases of 20–43% in the carotenoid content of fresh orange juice (from 3.99 to 4.78–5.70 mg l^?1). A non‐uniform behaviour of high‐pressure treatments was detected. An increase in time (beyond 5 min) or temperature (above 30 °C) of treatment did not improve the amount of carotenoids extracted. Owing to better extraction of carotenoids, an increase in vitamin A value from 164 to 238 RE l^?1 (45%) was achieved with the 350 MPa/30 °C/5 min treatment. No correlation was found between the increase in carotenoid amount extracted and the free radical‐scavenging activity. © 2002 Society of Chemical Industry     

浓缩胡萝卜汁加工工艺研究

以胡萝卜为原料加工成浓缩胡萝卜汁,研究浓缩胡萝卜汁加工工艺。结果表明,胡萝卜果实榨汁时,用150mg/kg 果胶酶在50℃下酶解处理果浆50min,可提高出汁率20%。通过正交试验,确定了闪蒸真空浓缩最佳工艺参数值：浓缩温度50～55℃、真空度9.33 × 104～10.0 × 104Pa、蒸汽压力7.5 × 104～8.0 × 104MPa、果汁流量6.0 × 103～6.5 × 103L/h;贮存温度≤－ 18℃,产品pH 值、总酸和β- 胡萝卜素基本无变化。     

Selection of Process Conditions for High Pressure Pasteurization of Sea Buckthorn Juice Retaining High Antioxidant Activity

Sea buckthorn berries juice is a nutritious beverage, rich in vitamin C and carotenoids with high antioxidant activity. The main requirements for a freshly squeezed sea buckthorn juice production are the cloud stability and antioxidant activity retention after processing. Appropriate process technologies and conditions have to be applied in order to inactivate pectin methyl esterase (PME), responsible for cloud loss, while maintaining the nutritional characteristics and antioxidant activity of the juice. The objectives of the present work were to study and model the effect of thermal treatment and high pressure (HP) processing on the inactivation kinetics of endogenous PME and on total antioxidant activity alteration. Thermal treatment significantly affected PME inactivation and residual antioxidant activity. Processing even at mild process conditions (60 °C for 1 min) resulted in 2.5-fold antioxidant activity reduction and 50 % PME inactivation compared to untreated sample. Pressure and temperature acted synergistically for PME inactivation that followed first-order kinetics with a residual PME activity at all pressure–temperature combinations used (200–600 MPa and 25–35 °C). The effect of temperature and pressure on the inactivation rate constants was expressed through the activation energy and activation volume, respectively. Values of 163 kJ/mol and ?17 mL/mol at reference pressure of 600 MPa and reference temperature of 35 °C were estimated, respectively. Antioxidant activity of the samples was expressed through the determination of the effective concentration (EC₅₀). A slight increase in sea buckthorn antioxidant activity when applying pressures (200–600 MPa) at ambient temperature (25 °C) was observed compared to the corresponding value of untreated juice. Processing at higher temperatures did not significantly alter the total antioxidant activity of sea buckthorn juice. For sample treated at 600 MPa–35 °C for 5 min, a 5 % reduction of total antioxidant activity was observed. These conditions are proposed as effective process conditions for sea buckthorn juice cold pasteurization, based on the higher antioxidant activity retention and simultaneous PME inactivation.     

不同高压均质条件对罗望子浊汁稳定性及抗氧化活性的影响

为提高罗望子浊汁物理稳定性和抗氧化活性,该实验研究了均质压力、进料温度和均质次数对罗望子浊汁稳定性和抗氧化活性的影响。结果表明,一定范围内随均质压力(0～25 MPa)的增加、进料温度(30～50℃)的提高和均质次数(1～3次)的增加,浊汁的粒度减小,稳定性提高。过高的进料温度(60～70℃)和均质次数(4～5次)导致浊汁稳定性下降。浊汁多糖含量对均质条件的变化不敏感,适当的均质压力(0～15 MPa)可以提高浊汁中总酚、黄酮含量、DPPH自由基和羟自由基清除能力。进料温度升高和均质次数增加导致浊汁中总酚、黄酮含量和ABTS自由基清除能力相比对照组显著降低(P <0. 05)。浊汁总酚和黄酮含量与3种自由基清除能力间呈现较好相关性。正交实验得到最优工艺条件为进料温度50℃、均质压力25 MPa、均质次数2次,此条件下,浊汁离心沉淀率为1. 18%、上清液浊度为435. 50NTU,显著优于对照组,可用于生产。     

Kinetic model of sugar diffusion from sugar beet tissue treated by pulsed electric field

Extraction of sugar from sugar beet slices was studied following various pulsed electric field (PEF) treatments (intensities from 300 to 800 V cm^?1 and number of pulses varying between 50 and 1000). Slices treated by PEF were immersed in water at ambient temperature at a liquid/solid ratio of 3. A significant increase in extraction yield was observed. This enhancement was due to permeabilisation of the cellular membrane and to the additional quantity of juice appearing on the surface of slices after PEF treatment being extracted rapidly by convection. The optimal conditions of PEF treatment were an intensity of 670 V cm^?1 and 250 pulses. The extraction kinetics was studied on the basis of two approaches: Fick's diffusion equation and a two‐exponential kinetic model. The coefficient of diffusion was only slightly influenced by the conditions of PEF treatment. The two‐exponential model successfully described both the rapid and prolonged stages of extraction. By heating the solution at mild temperatures of 30–50 °C, the coefficient of diffusion was increased and the kinetics of extraction was enhanced. The quality of cellular juice obtained after PEF treatment was higher than that of juice obtained after thermal pretreatment at 75 °C. Copyright © 2004 Society of Chemical Industry     

陶瓷膜在哈密瓜汁微滤除菌工艺中的应用研究

哈密瓜汁对热敏感,为了减少因热处理导致的营养成分和风味物质的损失,采用无机陶瓷膜对哈密瓜汁进行微滤除菌。通过研究三种孔径膜的膜通量、微滤前后哈密瓜汁营养成分的变化及除菌效果,选择最适的膜孔径,并在此基础上选择最适的操作压力和进料温度,从而确定最佳的微滤除菌工艺参数。结果表明:最佳的工艺参数为膜孔径0.2μm,操作压力0.2MPa,进料温度25℃。在此条件下处理的哈密瓜汁透光度可达98.8%,浊度为2.61NTU,菌落总数为13CFU.mL-1,其中大肠菌群、霉菌、酵母菌均未检出。     

Analysis of the fouling mechanisms during cross-flow ultrafiltration of apple juice

The purpose of this work was to study the fouling mechanisms of a Carbosep^® M8 membrane during the cross-flow ultrafiltration of apple juice. A new fouling model has been developed that simultaneously considers membrane blocking within the pores, at the pore mouths and by cake formation at the membrane surface. Membrane fouling by apple juice was due to internal pore blocking as well as cake formation. When operating ultrafiltration at a transmembrane pressure of 150 kPa and a cross-flow velocity of 7 m/s, fouling was minimal with a gradual decrease of the relative contribution of cake formation; however, transmembrane pressure still exceeds critical pressure. The fouling model predicts no cake formation at a cross-flow velocity of 7.4 m/s and a transmembrane pressure of 150 kPa or at a cross-flow velocity of 7.0 m/s and a transmembrane pressure of 120 kPa. Under these conditions, internal membrane blocking would be the only mechanism responsible for the decrease of permeate flux.     

Effect of membrane property and operating conditions on phytochemical properties and permeate flux during clarification of pineapple juice

The effects of membrane property on the permeate flux, membrane fouling and quality of clarified pineapple juice were studied. Both microfiltration (membrane pore size of 0.1 and 0.2 μm) and ultrafiltration (membrane molecular weight cut-off (MWCO) of 30 and 100 kDa) membranes were employed. Membrane filtration did not have significant effects on the pH, reducing sugar and acidity of clarified juice whereas the suspended solids and microorganism were completely removed. The 0.2 μm membrane gave the highest permeate flux, total vitamin C content, total phenolic content and antioxidant capacity as well as the highest value of irreversible fouling. Based on these results, the membrane with pore size of 0.2 μm was considered to be the most suitable membrane for the clarification of pineapple juice. The optimum operating conditions for the clarification pineapple juice by membrane filtration was a cross-flow velocity of 3.4 ms⁻¹ and transmembrane pressure (TMP) of 0.7 bar. An average flux of about 37 lm⁻² h⁻¹ was obtained during the microfiltration of pineapple juice under the optimum conditions using batch concentration mode.     

Inactivation kinetics of polygalacturonase in tomato juice

The inactivation kinetics of polygalacturonase (PG) in tomato juice was studied during thermal and high-pressure/thermal processing. In the temperature range of 55–70 °C the thermal inactivation of polygalacturonase in tomato juice followed a fractional conversion model, with a thermostable fraction of approximately 14%. Under conditions of combined high-pressure/thermal processing, 200–550 MPa/5–50 °C, PG inactivation presented first order kinetics. A mathematical model to describe the inactivation rate constant as a function of pressure and temperature was formulated. Industrial relevance: Polygalacturonase is responsible for the decrease of viscosity in tomato-based products. However, little research on thermal and high pressure/thermal inactivation kinetics of tomato Polygalacturonase has been reported. This research clearly shows that it is possible to selectively inactivate PG by high pressure/thermal processing without applying high temperatures. This leads to tomato-based products with improved functional properties while other quality attributes (color, flavor, nutritional value) are maintained.     

Cross-flow Microfiltration with Gas Backwash of Apple Juice

Cross-flow microfiltration (MF) was applied for clarification of commercially pressed depectinized apple juices and pectin containing artificial apple juice suspensions under continuous low pressure inlet conditions (35 kPa - 209 kPa). Periodic gas backwash (air or N₂) removed solids from exteriors of 0.2 μm cut-off hollow fiber polypropylene membranes. Flux and nephelos turbidity units (NTU) of filtrates for both commercial juices and artificial juices were evaluated. Commercial juices after vacuum filtration and MF had 100–110 L/m²/hr flux during 2 hr operation. Low pectin (1%) artificial juices had ～70 L/m²/hr flux during 1.5 hr. NTUs of filtrates from all treatments were <0.69. All filtrates were commercially sterile.     

Combinatorial optimality of membrane morphology and feedstock during microfiltration of bottle gourd juice

The combinatorial optimality of membrane morphology and process parameters during dead end microfiltration of bottle gourd juice have been addressed in this article. Saw dust and kaolin based low cost ceramic membranes with varied morphology have been chosen to evaluate upon their microfiltration performance. For the chosen membranes, fresh, paper filtered and centrifuged juice samples were considered along with transmembrane pressure differential as process parameters. Combinatorial optimality was based on flux decline trends, fitness of fouling models, irreversible and reversible fouling data, irreversible permeation resistance and nutritional analysis of the permeate samples. An interesting feature of the article had been with respect to feed constitution playing a critical role in influencing the optimal choice of membrane morphology and transmembrane pressure differentials. Among all cases, paper filtered bottle gourd juice, 0.75 μm membrane and 137.9 kPa transmembrane pressure were found to be the best choice in terms of minimal irreversible fouling, lowest protein content, good clarity, good polyphenol and antioxidant activity in the permeate and appropriate flux.     

CONSEQUENCES of FOULING and MACROMOLECULE ADSORPTION ONTO ULTRAFILTRATION MEMBRANE FOR PINEAPPLE JUICE PROCESSING

Pineapple juice samples were ultrafiltrated using a polysulfone 10,000 molecular weight cut-off (MWCO) membrane. However, to facilitate operations, the ultrafiltration experiments were preceeded by fractionation of juice samples using sequentially Microfiltration/Diafiltration and Ultrafiltration/Diafiltration with 8 μm; 0.4 μm; 0.2 μm and 0.1 μm membranes, using three specific experimental procedures. the 10,000 MWCO membrane was cleansed using a 40°C IN NaOH solution for a minimum of 30 min, to restore optimal membrane water permeation flux. the effects of selective fractionation processes, pretreatments (using antifoaming agent, hemicellulase, and ammonium sulfate saturation), on permeation rates, concentration levels, protein rejection and protein yields were determined. Water permeation fluxes, measured before and after each UF operation showed a dramatic flux drop from 313 L/hm² to 91 L/hm² within seven successive 10,000 MWCO membrane experiments. This occurred inspite of suitable membrane washing conditions, pretreatments and selective fractionation processing of samples. the modification, mainly due to fouling, of the integrity of the 10,000 MWCO membrane relative to concentration level was investigated.     

均质对毛酸浆果汁稳定性的影响及其粒径形态表征

研究均质条件对毛酸浆果汁粒径分布及果汁稳定性的影响。在均质压力、温度、次数对果汁稳定系数、离心沉淀率影响的单因素试验基础上,采用正交试验对高压均质条件进行优化。结果表明：均质压力20 MPa、均质温度45 ℃、均质2 次时,毛酸浆果汁稳定系数为0.798,离心沉淀率为2.10%。在该工艺条件下,利用纳米粒度仪对毛酸浆果汁均质前后粒径大小分布进行比对,均质前果汁粒径分布在0.260 1～4.96 μm范围,含量为100%,平均粒径为4.561 μm;均质后粒径分布则为1.018～4.548 μm（含量为96.5%）和0.138 7～0.793 5 μm（含量为3.5%）,平均粒径为1.963 μm。同时,对均质前后果汁颗粒形态进行扫描电镜观察,可见均质后果汁细胞碎片明显增多,呈分散状态。     

超滤法澄清西番莲果汁的研究

以寻求提高西番莲原汁超滤时的渗透通量为目的，用国产芳香聚酰胺膜平板超滤器进行试验，对超滤操作条件，果汁预处理，膜的清洗进行研究。结果表明，西番莲原汁超滤时渗透通量最高的操作压力为0．15MPa，最佳进料速度为22mL/s，操作温度为室温；原汁经海藻酸钠—碳酸钠澄清剂预处理后可以明显增大渗透通量；超滤处理后。原汁的西番莲固有滋味和品质得到较好保留。采用超滤澄清法生产高质量的西番莲原汁是可行的。     

Evaluation of spray drying conditions on properties of microencapsulated oregano essential oil

Response surface methodology (RSM) was employed to investigate variations in powder characteristics with respect to spray drying operating parameters including both feed rates (L min^?1) and inlet temperatures (°C). Inlet temperatures around 180 °C provided the lowest values for moisture. Powder recovery was significantly affected (P < 0.10) by inlet air temperature and feed rate, where a raise in inlet temperature and feed rate resulted in higher powder recovery. No significant difference (P > 0.05) was observed for water activity, solubility and hygroscopicity between treatments. Regarding oil retention, the results showed a significant (P < 0.05) interaction between the two studied factors. A tendency for higher values of oil retention was observed when using combinations of high inlet temperatures/low feed rates and low inlet temperatures/high feed rates. Particle size distribution averaged 2.0, 8.1 and 18.3 μm for D₁₀, D₅₀ and D₉₀, respectively. The morphology of particles showed no cracks in most capsules. The results indicate that high temperature (185 °C) and moderated feed rate (0.63 L min^?1) are the best spray drying conditions.     

Chicory juice clarification by membrane filtration using rotating disk module

Clarification is the first step of inulin production from chicory juice, and membrane filtration as an alternative can greatly simplify this process, increase juice yield, improve product quality, and reduce the cost and waste volume. In this study, a rotating disk module (RDM) was used to investigate the clarification of chicory juice by four micro- and ultrafiltration membranes. Compared with dead end filtration, the RDM had a much higher permeate flux and product quality. High rotating speeds produced high permeate fluxes and reduced flux decline, because of the strong back transport of foulant from fouling layer to feed solution. At high rotating speeds of 1500–2000 rpm, the permeate flux increased with membrane pore size and transmembrane pressure (TMP), while at low rotating speeds (<1000 rpm), permeate flux was independent of membrane type and TMP due to a thick deposited fouling layer as a dominant filtration resistance, while carbohydrate transmission decreased at higher TMP because of denser cake layer as an additional selective membrane. The highest carbohydrate transmission (∼98%) and desirable permeate turbidity (2.4 NTU) was obtained at a TMP of 75 kPa and a rotating speed of 2000 rpm for FSM0.45PP membrane. With the RDM, the Volume Reduction Ratio (VRR) could reach 10 with a high permeate flux (106 L m⁻² h⁻¹) in the concentration test, and permeate was still rich in carbohydrate and well clarified. Chemical cleaning with 0.5% P3-ultrasil 10 detergent solution was able to recover 90% water flux of fouled membrane.