Microfiltration and Ultrafiltration Comparison for Apple Juice Clarification

Unpasteurized raw apple juice processed by microfiltration (MF) or ultrafiltration (UF) was evaluated for quality and the methods compared for process efficiency. Juice permeate was analyzed for total solids, soluble solids, color, turbidity, pH and acidity. Apple juice processed by MF was significantly (p < 0.05) darker, more turbid, contained higher total and soluble solids than juice processed with UF, and was preferred by a taste panel. MF processed more permeate per unit time than UF under similar operating conditions with no noticeable difference in power consumption (watt-hr/L).     

Clarification of Apple Juice Using Polymeric Ultrafiltration Membranes: a Comparative Evaluation of Membrane Fouling and Juice Quality

The aim of this study was to evaluate the performance of three different commercial polymeric ultrafiltration (UF) membranes during clarification of raw apple juice, comparatively. The influence of membrane pore size, roughness, and hydrophobicity on flux profile and fouling was investigated. The initial flux was simultaneously decreased at the beginning of the process, and quite steady flux was obtained in the membranes with rougher surface and more hydrophobic nature. As the pore size and hydrophobicity increased, the reversible fouling became the major resistance, while cake formation was more prominent for the membranes with narrower pore size. The overall quality results revealed that the main quality characteristics of the raw juice can be better retained by using the membranes that have higher resistance to fouling.     

Microfiltration and Ultrafiltration Ceramic Membranes for Apple Juice Clarification

Depectinized control (CTJ) and ascorbic acid treated (AAJ) apple juices were filtered through microfiltration (MF, 0.2 m) and ultrafiltration (UF, 0.02 m) ceramic tubular membranes. Under optimal conditions (8 m/s, 414 kPa and 50°C), the UF membrane resulted in higher steady state flux and less fouling than the MF membrane for both juices. AAJ produced by addition of AA at milling had lower flux for both MF and UF. The chemical, physical and sensory properties of apple juices from MF and UF membranes were similar and changes during storage were comparable.     

Improved Ultrafiltration for Color Reduction and Stabilization of Apple Juice

Polyphenols that are responsible for haze-formation and browning during storage of clear apple juice and concentrates could be selectively removed by an ultrafiltration process using membranes of polyether sulfone and polyvinylpyrrolidone. Results were compared with those from commercial UF membranes made out of regenerated cellulose acetate. The effects of laccase treatment on removal of polyphenols and color in apple juice were also investigated. Custom membranes were effective to reduce the amount of polyphenols. A remarkable desired color removal of apple juice could also be achieved using these membranes. Resulting products were stable in color and clarity at 50°C up to 6 wk. Laccase treatment increased the percentage removal of polyphenols from apple juices. However, laccase treated samples were more susceptible to coloration and haze-formation during storage.     

Production of Apple Juice by Single Pass Metallic Membrane Ultrafiltration

A new process utilizing single pass metallic membrane ultrafiltration (UF) was developed to produce apple juice. Pureed whole apples were treated with cellulase and pectinase at 50°C for 2 hr, resulting in a 60% decrease in viscosity. To obtain clarified juice, enzyme treated puree was pumped through a single-pass, tubular membrane system consisting of a metallic oxide membrane formed-in-place on the porous structure of sintered stainless steel tubes. Juice yields of 80–85% were obtained with a single pass, and gas chromatographic profiles of ultrafiltered juice were nearly identical to that of the original apple puree. Permeabilities and sugar rejection characteristics of the UF system were dependent on tube diameter.     

Production of Microbiologically Stable Apple Juice by Metallic Membrane Ultrafiltration

The potential for production of microbiologically stable apple juice by metallic membrane ultrafiltration was assessed. Thermal sterilization treatments caused no detectable changes in membrane performance. Sterile membranes were challenged with approximately 3 × 10⁶ colony forming units per gram of each of three organisms, Pseudomonas diminuta, Bacillus coagulans, and Saccharomyces cerevisiae, suspended in apple puree or peptone. Reductions achieved by ultrafiltration of peptone at operating pressure were 5.1, 7.6, and >9.0 logs for the three organisms, respectively. Reductions of organisms in apple puree were at least 1.5 logs greater. Metallic membranes eliminated yeasts and molds from juice. Apple juice produced from uninoculated apple puree was stable at 20–25°C for 1 yr.     

Solute and Enzyme Recoveries in Apple Juice Clarification using Ultrafiltration

Enzyme treated apple juices, obtained after pressing on a commercial processing line, were clarified by UF using a plate and frame system. The 50,000 molecular weight cut-off membranes operated at 50°C and 5 bar pressure yielded average recovery of 99.6% and 99.3% soluble solids and titratable acids, respectively, in the permeate and rejected 36.3% of the residual pectinase activity which was available for possible reuse. Proper membrane cleaning to maintain high flux was very important in UF clarification; a 1% Ultrasil solution was more efficient than a 0.1% NaOH solution and reduced need for centrifugation and/ or vacuum filtration prior to UF.     

Adsorptive Removal of Patulin from Apple Juice Using Ca‐Alginate‐Activated Carbon Beads

This study aimed to investigate the adsorption of patulin from apple juice by Ca‐alginate‐activated carbon (Ca‐alginate‐AC) beads. The capacity of patulin was determined by high‐performance liquid chromatography. The results showed that Ca‐alginate‐AC beads have significant ability to reduce patulin from contaminated apple juice. Furthermore, the adsorption process did not affect the quality of apple juice. The effects of contact time, initial patulin concentration, adsorbent dose, and temperature were assessed. The removal percentage of patulin increased with contact time, adsorbent dose, and temperature. A reduction was also noted to bind patulin at increased levels of contamination. The equilibrium data were fitted to Langmuir, Freundlich, and Temkin isotherm models and the isotherm constants were calculated at different temperatures. The adsorption equilibrium was best described by the Freundlich isotherm (R² > 0.990). The pseudo 1st‐order model was found to describe the kinetic data satisfactorily. Thermodynamic parameters such as standard Gibbs free energy (ΔG??), standard enthalpy (ΔH?), and standard entropy (ΔS?) were evaluated. The results showed that the adsorption was spontaneous and endothermic nature.     

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.     

Ultrafiltration of Banana (Musa acuminata) Juice Using Hollow Fibers for Enhanced Shelf Life

Banana juice was clarified by cross flow ultrafiltration using a hollow fiber module under total recycle mode. Three surface-modified polysulfone-based membrane cartridges with molecular weight cut-offs 10, 27, and 44 kDa were used to identify the most suitable membrane. The effects of operating conditions—namely, transmembrane pressure drop and cross flow rate on the permeate flux and permeate quality, have been investigated. The quality of the clarified juice was evaluated in terms of viscosity, clarity, color, alcohol insoluble solids, total soluble sugar, pH, protein, and polyphenol content. The results showed that the membrane of molecular weight cut-off 27 kDa was suitable. The permeate flux depended strongly on the transmembrane pressure drop, but its variation on cross flow rate was insignificant. The clarified juice had high clarity and no pectineous materials (in terms of alcohol insoluble solids). It contained significant amount of polyphenol and protein. The storage study indicated that the juice could be successfully stored for 1 month without any additive and preservative, keeping its natural nutritional qualities, taste, and flavor intact.     

Pasteurisation of Apple Juice by Using Microwaves

Exposure of Escherichia coli to microwave treatments results in a reduction of the microbial population in apple juice. This research determined the effect of pasteurisation at different power levels (270-900 W) on the microbial quality of apple juice, using a home 2450 MHz microwave. Data obtained were compared with conventional pasteurisation (83 °C for 30 s). Apple juice pasteurisation at 720-900 W for 60-90 s resulted in a 2-4 logs population reduction. Using a linear model, the D -values ranged from 0.42±0.03 min at 900 W to 3.88±0.26 min at 270 W. The value forz was 652.5±2.16 W (58.5±0.4 °C). These observations indicate that inactivation of E. coli is due to heat.     

陶瓷膜超滤净化石灰法制糖清汁

对孔径为0.04?μm的陶瓷超滤膜进一步净化石灰法制糖的清汁进行研究,在跨膜压差0.45～0.50?MPa、膜面流速4.0～4.5?m/s、过滤温度75～97?℃的条件下过滤甘蔗汁30?h,膜渗透通量从350.6?L/（m2·h）降低至160.2?L/（m2·h）,平均通量为177.8?L/（m2·h）,能满足工业化生产的需求。甘蔗汁经陶瓷膜过滤后品质被进一步提升,简纯度可提高2.01?个单位,色素去除率为20.20%,澄清度从79.18%提升至99.98%。研究膜污染形成发现,陶瓷膜过滤甘蔗汁会在膜表面形成一层污染层,膜污染物的主要成分为有机物（多糖、蛋白质、酯类及酚类等物质）,同时还含有少量的Na、Mg、Al、Si、P、Cl、K、Ca及Fe等无机成分。污染膜依次采用工业净水、1%?NaOH-0.5%?NaClO混合溶液、0.5%?HNO3溶液清洗,膜通量恢复率均高于95.5%,重复性较好,是一种有效的膜清洗方法。     

Kiwifruit Juice Processing Using Heat Treatment Techniques and Ultrafiltration

Heat treatment of kiwifruit juice caused formation of a heavy protein precipitate. Celite filtration removed the precipitate giving a clear, heat-stable juice which could be readily concentrated and reconstituted. Hollow fibre ultrafiltration was used to clarify and nonthermally sterilize kiwifruit juice. Virtually all the soluble proteolytic enzyme, actinidin, remained in the retentate although there was some loss of enzymatic activity. Some sedimentation was observed in both conventionally prepared and ultrafiltered juices prepared in the 1980 season, but not in 1981. A procyanidin: protein haze formed immediately in certain clarified kiwifruit juice: apple juice blends.     

固定化果胶酶提高苹果出汁率的研究

采用固定化果胶酶处理红富士苹果浆,在苹果浆pH值、固定化果胶酶水解温度、固定化果胶酶使用质量和固定化果胶酶水解时间对苹果浆出汁率的影响等单因素试验的基础上,采用响应面法分析,探索固定化果胶酶提高苹果浆出汁率的最佳条件。最佳工艺条件为苹果浆适宜pH3.43、固定化果胶酶与苹果浆质量比为1:15、酶促反应温度49.4℃、酶促反应时间3.50h。固定化果胶酶反复使用10次时,苹果浆的出汁率为62.421%,与对照组相比仍提高约13%。     

Inactivation of in Apple Juice by Radio Frequency Electric Fields

ABSTRACT: Heat pasteurization may detrimentally affect the quality of fruit and vegetable juices; hence, nonthermal pasteurization methods are actively being developed. Radio frequency electric fields processing has recently been shown to inactivate yeast in water at near-ambient temperatures. The objective of this study was to extend the radio frequency electric fields (RFEF) technique to inactivate bacteria in apple juice. A converged-field treatment chamber was developed that enabled high-intensity RFEF to be applied to apple juice using a 4-kW power supply. Finite element analyses indicated that uniform fields were generated in the treatment chamber. Escherichia coli K12 in apple juice was exposed for 0.17 ms to electric field strengths of up to 26 kV/cm peak over a frequency range of 15 to 70 kHz. The population of E. coli was reduced by 1.8 log following exposure to an 18 kV/cm field at an outlet temperature of 50 °C. Raising the temperature increased inactivation. Intensifying the electric field up to 16 kV/cm increased inactivation; however, above this intensity, inactivation remained constant. Radio frequencies of 15 and 20 kHz inactivated E. coli better than frequencies of 30 to 70 kHz. Inactivation was independent of the initial microbial concentration between 4.3 and 6.2 log colony-forming units (CFU)/mL. Applying 3 treatment stages at 50 °C increased inactivation to 3 log. The electric energy for the RFEF process was 300 J/mL. The results of the present study provide the 1st evidence that RFEF processing inactivates bacteria in fruit juice at moderately low temperatures.     

Molecular Weight Cut-off of Ultrafiltration Membranes and the Quality and Stability of Apple Juice

The quality and stability of apple juice clarified using 10,000 (10K), 50K, 100K, and 500K daltons molecular weight cut-off (MWCO) hollow fiber membranes were examined . Ultrafiltered juice was tested for initial stability, starch presence, pH, total acidity, total solids, soluble solids, turbidity, browning, Hunter color, total phenols, and sensory attributes. Turbidity, browning, total phenols, and sensory color were different depending upon the MWCO used. Samples were stored at 18°C and 43°C for 6 months and evaluated monthly. At 18°C, there were no significant changes but initial differences due to membranes remained. At 43°C, the increase in turbidity, browning, and chroma, as well as the decrease in lightness and hue with time, were significant. Reaction rates were all the same independent of the MWCO except for chroma.     

Enhanced Anthocyanin Extraction from Red Cabbage Using Pulsed Electric Field Processing

Abstract: This study was conducted to evaluate the effect of pulsed electric field (PEF) treatment on anthocyanin extraction from red cabbage using water as a solvent. Mashed cabbage was placed in a batch treatment chamber and subjected to PEF (2.5 kV/cm electric field strength; 15 μs pulse width and 50 pulses, specific energy 15.63 J/g). Extracted anthocyanin concentrations (16 to 889 μg/mL) were determined using HPLC. Heat and light stabilities of the control and PEF-treated samples, having approximately the same initial concentrations, were studied. PEF treatments enhanced total anthocyanin extraction in water from red cabbage by 2.15 times with a higher proportion of nonacylated forms than the control (P < 0.05). The heat and light stabilities of the PEF-treated samples and control samples were not significantly different (P > 0.05). Practical Application: An innovative pretreatment technology, pulsed electric field processing, enhanced total anthocyanin extraction in water from red cabbage by 2.15 times. Manufacturers of natural colors can use this technology to extract anthocyanins from red cabbage efficiently.     

Commercial-Scale Pulsed Electric Field Processing of Orange Juice

Effects of commercial‐scale pulsed electric field (PEF) processing on the microbial stability, ascorbic acid, flavor compounds, color, Brix, pH, and sensory properties of orange juice were studied and compared with those of thermal processing. Freshly squeezed orange juice was thermally processed at 90 °C for 90 s or processed by PEF at 40 kV/cm for 97 ms. Both thermally processed and PEF‐processed juices showed microbial shelf life at 4 °C for 196 d. PEF‐processed juice retained more ascorbic acid, flavor, and color than thermally processed juice (P<0.05). Sensory evaluation of texture, flavor, and overall acceptability were ranked highest for control juice, followed by PEF‐processed juice and then by thermally processed juice (P<0.01).