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.     

Influence of gas sparging on clarification of pineapple wine by microfiltration

A microfiltration process with a tubular ceramic membrane was applied for clarification of pineapple wine. The process was operated with the membrane pore size of 0.2 μm at transmembrane pressure of 2 bar and crossflow velocity of 2.0 m/s. The effects of gas sparging on permeate flux, fouling and quality of clarified wine were studied. It was found that a relatively low gas sparging rate could increase permeate flux up to 138%. Further increase of the gas sparging rate did not improve permeate flux compared with that without gas sparging. Gas sparging affected the density of cake layer. Increasing gas sparging rate led to an increase in specific cake resistance. It was observed that increasing gas sparging rate could reduce reversible fouling rather than irreversible fouling. The turbidity of pineapple wine was reduced and a clear product with bright yellow color was obtained after microfiltration. The negative effect of gas sparging which caused a loss of alcohol content in the wine was also observed.     

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.     

Clarification of passion fruit juice by microfiltration: Analyses of operating parameters,study of membrane fouling and juice quality

In this study, the performance of two membranes were compared – tubular ceramic and hollow fiber poly(imide) – under transmembrane pressure of 0.5 and 1 bar, for the clarification of passion fruit pulp pre-treated by centrifugation and enzymatic treatment at the concentrations of 150 and 300 ppm. Nutritional and sensorial qualities of the clarified juice obtained were evaluated. Thus, it was possible to observe that the most adequate condition for the clarification of passion fruit pulp was with enzymatic treatment at 150 ppm and its posterior microfiltration at the ceramic tubular membrane of 0.3 μm with transmembrane pressure of 0.5 bar. The fouling mechanism was identified by estimation of model parameters according to a nonlinear regression by Bayesian inference. Analysis of the fouling mechanism results revealed that hollow fiber membrane is controlled by a cake filtration mechanism, and internal pore blocking fouling mechanism controls ceramic tubular membrane.     

Physiochemical, antioxidant and whitening properties of extract from root cortices of mulberry as affected by membrane process

Extract from root cortices of mulberry (Morus alba, L.) was separated into permeate and retentate fractions using a membrane system equipped with either a microfiltration membrane or one of four molecular weight cut-off ultrafiltration membranes. The effects of membrane process at volume concentration ratio (VCR)=4 on the physiochemical characteristics, the contents of active compounds, antioxidant ability, and whitening capability (tyrosinase inhibitory activity) in permeate and retentate were evaluated. The clarification degree, antioxidant effects, and whitening capability of the permeates increased as compared to those of feed. In addition, permeate treated with a 0.45 μm microfiltration membrane exhibited less fouling layer and specific resistance (αpC_B=622.8 m⁻²×10⁻⁶) and thus had a higher permeate flux than treated with other ultrafiltration membranes (αpC_B=786.1-1025.3 m⁻²×10⁻⁶). A higher content of active compounds, such as chlorogenoic acid and p-hydroxybenzoic acid may explain higher antioxidant and whitening capabilities in permeate of extracts from root cortices of mulberry.     

ANALYSIS OF THE FOULING MECHANISM IN MICROFILTRATION OF ORANGE JUICE

The purpose of this work is theoretical and experimental evaluation of fouling effects on flux performance in clarification of freshly squeezed orange juice by cross-flow microfiltration. To identify optimum operating conditions to minimize fouling effects, juice was microfiltered on a laboratory scale plant varying axial velocity and transmembrane pressure difference. The observed flux decay was modeled using a modified form of the differential equation used to describe classical dead-end filtration processes. The mechanism of fouling during cross-flow microfiltration was identified by estimation of the model parameters according to a nonlinear regression optimization procedure. Analysis of the results revealed that the separation process is controlled by a cake filtration fouling mechanism as the juice is fed at relatively low velocity (i.e., Re = 5000) and the system is operated at low transmembrane pressure difference. In these operating conditions the permeate flux decays within the first 20–30 min to gradually achieve a limit value. At higher Reynolds number (Re = 15,000), an increase in applied transmembrane pressure (i.e., from 0.3 to 1 bar) allows the limit permeate flux to increase by a factor of about 4. In these conditions the filtration process is controlled by a complete pore blocking fouling mechanism, and the permeate flux becomes approximately invariant with respect to time, and a negligible decay may be observed. Evaluation of specific energy consumption involved in the filtration process is reported.     

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.     

Identification of optimal membrane morphological parameters during microfiltration of mosambi juice using low cost ceramic membranes

In this work, experimental investigations were carried out for the identification of optimal membrane morphological parameters (pore size distribution, average pore size and porosity) during microfiltration (MF) of mosambi juice using low cost ceramic membranes. Four different low cost ceramic membranes with different pore diameters (d_m) and porosities (?) were subjected to MF studies to evaluate the effect of d_m and ? on permeation characteristics (permeate flux and juice quality) of centrifuged mosambi juice (CJ) and enzyme treated centrifuged mosambi juice (ETCJ). Subsequently, a convenient factor namely effective permeable area factor (?_md_m²) was evaluated to provide greater insights in the fouling phenomena. Various physio-chemical properties such as colour, clarity, pH, citric acid content, density, total soluble solid (TSS) and alcohol insoluble solids (AIS) were measured for both feed and permeate juice samples to evaluate the effect of ?_md_m² on juice quality. Typical permeate fluxes were observed to vary from 5.78 × 10⁻⁶ to 13.45 × 10⁻⁶ m³/m² s for CJ and 14.07 × 10⁻⁶ to 60.64 × 10⁻⁶ m³/m² s for ETCJ at 82.7 kPa (ΔP) for different membranes whose ?_md_m² varied from 0.249 to 0.783 μm². Among different membrane pore blocking models, flux decline by cake filtration was found to be the best fitted model. The cake filtration model constant (k_c) was found to vary with ΔP and ?_md_m² and was empirically correlated. Phenomenological models were proposed to illustrate the dependency of total hydraulic resistance of membrane on ?_md_m², ΔP and time (t). Based on experimental as well as theoretical investigations, membranes with ?_md_m² up to 0.443 μm² for CJ and 0.294 μm² for ETCJ and a ΔP of 82.7 kPa were recommended for MF of mosambi juice.     

Fluid dynamic gauging of microfiltration membranes fouled with sugar beet molasses

Fluid dynamic gauging (FDG) was used to track the thickness of the cake layer formed during the microfiltration of a 45° Brix molasses solution using a 1.5 μm polysulphone membrane. A simultaneous measure of flux and deposit thickness throughout the full membrane operating cycle is reported. Asymptotic fouling thicknesses of ca. 100 μm are developed after 30 min of filtration. Accordingly, flux declines are severe at ca. 93%. Permeate line closed (PLC) operation leads to the complete removal of the deposit layer, and the recovery of 60% of the flux. However, permeate line open (PLO) operation leads to only a 50% flux recovery and an asymptotic deposit thickness of 10 μm. An initial increase and subsequent reduction in flux during chemical cleaning has also been recorded for both acid and alkali cleaning regimes. Effective cleaning regimes for membranes fouled by molasses require an alkali stage followed by an acid stage.     

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.     

Mathematical modeling of crossflow microfiltration of diluted malt extract suspension by tubular ceramic membranes

The practical application of microfiltration in brewing industry is hindered by severe membrane fouling and subsequent permeate flux decline. A theoretical and experimental study on the effect of operating parameters, which influence the crossflow microfiltration of beer and beer quality was performed. A mathematical model is developed to better understanding of the fouling layer characteristics. The experiments were conducted for different ranges of pressures, temperatures and shear rates. An optimum transmembrane pressure of 1.1 bar is suggested to maximize both the steady state and average permeate fluxes. The results of numerical simulation were in a good accordance with the experimental data.     

基于红糖生产的蔗汁陶瓷膜过滤工艺技术

采用孔径为8、50 nm及500 nm的陶瓷膜对蔗汁进行过滤澄清生产红糖,解决传统红糖制作利用上浮撇泡方式处理蔗汁清净效果差导致成品糖品质低的问题.对比不同孔径陶瓷膜过滤蔗汁渗透通量大小、清净效果及能耗高低,结合红糖生产工艺需求,得出孔径为50 nm的陶瓷膜最适用于蔗汁过滤澄清生产红糖.在适合的操作条件下,考察孔径为5...     

Clarification of apple juice by electroflotation

Apple Juice industry is in search of a simplified technology which enables a quick clarification and stabilisation of apple juice. This study aimed to evaluate the potential of electroflotation as an alternative for the clarification of apple juice. Clarification of apple juice by electroflotation was first done at various current densities (10, 20 and 40 mA/cm²) with and without addition of gelatin (200 mg/l). Afterwards, the electroflotation treatments were done at a current density of 20 mA/cm² with various concentrations of added gelatin (0, 50, 100 and 200 mg/l). It was shown that electroflotation treatments alone was efficient to reduce the tannin and protein contents of apple juice. However, the decrease in the protein content was in large part due to the use of pectinases prior to the electroflotation treatments. The use of gelatin in combination with the electroflotation aided in the clarification process. The highest gelatin concentration used in this study (200 mg/l) resulted in a better reduction of tannin and protein levels, while a current density of 20 mA/cm² was found to be optimal. Turbidity observed in the juices clarified with electroflotation treatments was in average lower than 10 NTU but higher than 2 NTU which is generally required to produce a stable clarified juice. Brix degree and pH of the apple juice was not affected by the electroflotation treatments while the color was improved.

Industrial relevance

The production of clarified and stable apple juice is a subject of interest for the beverages industries. The clarification step which remained long and discontinuous implied the addition of a large quantity of pectolytic enzyme and of clarifying agents (such as gelatin) to the freshly pressed juice to induce the precipitation of proteins and other suspended matter in 15–20 h. Fining treatments were followed by a separation step usually consisting of decantation and classical filtration on filter-press, or flotation by dispersed gas. The development of membrane separation processes to replace the traditional approach has enabled the automation of the whole production resulting in lower labor requirement and a considerably shorter process time than the traditional process.However, the performance of membrane separation processes is influenced by the declining permeate flux with time, which is due to membrane fouling. In some instances, permeate flux decline makes membrane separation processes unattractive for the clarification of apple juice. To our knowledge, we are the first research group to use electroflotation (EF) for clarification of apple juice. It was shown that EF treatments alone were efficient to reduce the tannin and protein contents of apple juice. In addition, the use of gelatin in combination with the EF aided in the clarification process. Turbidity observed in the juices clarified with EF treatments for 30 min was in average lower than 10 NTU. Brix degree and pH of the apple juice were not affected by the EF treatments while the color was improved.When compared to the values reported in the literature for flotation by dispersed gas, it seems that EF shows better efficiency than flotation in decreasing the juice turbidity (99% decrease for EF as compared to 90% decrease for flotation). In addition, for experiments carried out by conventional flotation larger amount of fining agent are used (70–150 mg of gelatin/l, 400–800 mg/l of silica sol and 200–500 mg/l of bentonite). For these reasons, the new process we propose is advantageous when compared to the traditional flotation approach and it should have a measurable impact on the advancements in the production of clarified apple juice. If used as a pre-treatment to ultrafiltration clarification, it is expected that it would reduce membrane fouling resulting in higher productivity.     

Microfiltration of mosambi juice using low cost ceramic membrane

This work reports on microfiltration (MF) studies of mosambi juice using low cost ceramic membrane prepared from locally available inorganic precursors. Characterization of the prepared membrane was done by SEM analysis, porosity determination and pure water permeation experiments. The average pore diameter, total porosity and hydraulic resistance of the membrane were evaluated as 0.285 μm, 23.6% and 9.26 × 10¹¹ m²/m³, respectively. Dead-end MF experiments were performed for both centrifuged mosambi juice (CJ) and enzyme treated centrifuged mosambi juice (ETCJ). It was observed that after MF, important properties like TSS, pH, acidity and density of both CJ and ETCJ were almost unaffected. However, significant improvement in juice colour, clarity and AIS was observed. It was also observed that the clarified juice can be stored in refrigerated condition for more than 30 days without significant change in juice quality. Different membrane pore blocking models were used to analyze the observed permeate flux decline.     

Filtration of milk fat globule membrane fragments from acid buttermilk cheese whey

The proteins and polar lipids present in milk fat globule membrane (MFGM) fragments are gaining attention for their technological and nutritional properties. These MFGM fragments are preferentially enriched in side streams of the dairy industry, like butter serum, buttermilk, and whey. The objective of this study was to recover MFGM fragments from whey by tangential filtration techniques. Acid buttermilk cheese whey was chosen as a source for purification by tangential membrane filtration because it is relatively rich in MFGM-fragments and because casein micelles are absent. Polyethersulfone and cellulose acetate membranes of different pore sizes were evaluated on polar lipid and MFGM-protein retention upon filtration at 40°C. All fractions were analyzed for dry matter, ash, lipids, proteins, reducing sugars, polar lipid content by HPLC, and for the presence of MFGM proteins by sodium dodecyl sulfate-PAGE. A fouling coefficient was calculated. It was found that a thermocalcic aggregation whey pretreatment was very effective in the clarification of the whey, but resulted in low permeate fluxes and high retention of ash and whey proteins. By means of an experimental design, the influence of pH and temperature on the fouling and the retention of polar lipids (and thus MFGM fragments), proteins, and total lipids upon microfiltration with 0.15 μM cellulose acetate membrane was investigated. All models were highly significant, and no outliers were observed. By increasing the pH from 4.6 to 7.5, polar lipid retention at 50°C increased from 64 to 98%, whereas fouling of the filtration membrane was minimized. A 3-step diafiltration of acid whey under these conditions resulted in a polar lipid concentration of 6.79 g/100 g of dry matter. As such, this study shows that tangential filtration techniques are suited for the purification of MFGM fragments.     

The effect of ultrasound waves on the efficiency of membrane clarification of pomegranate juice

Pomegranate juice has a turbid appearance, which poses difficulties in its concentration process. Membrane clarification can be used to clarify pomegranate juice; however, membrane fouling reduces the permeate flux, limiting its effectiveness. Ultrasound at 30 kHz was used to reduce membrane fouling. Results were compared with the data obtained for membrane clarification without ultrasonic treatment at the same temperature. Results showed that permeate flux increased with ultrasonic treatment. Evaluation of different membrane fouling characteristics showed that the total membrane resistance fell due to the reduction in irreversible fouling and cake resistance. However, ultrasound did not affect the thick caking produced in membrane processing at low feed‐flow rates. Evaluation of the physicochemical properties of pomegranate juice showed that ultrasound can decrease antioxidant activity due to the reduction in total anthocyanin content. Also, total soluble solid content and acidity of pomegranate juice changed with ultrasonic treatment.     

膜分离技术在菠萝汁澄清中的应用研究

采用超滤膜和微滤膜对菠萝汁进行膜分离澄清实验,研究了不同操作参数(如压力、温度和时间)对膜分离效率及膜的清洗的影响,并对膜分离效果进行评价。结果表明,膜分离菠萝汁的最佳工作条件为:操作压力为0.06MPa,温度45℃;PVDF微滤膜的抗污染能力比PS超滤膜强,清洗后膜透水速率的恢复率达到了97.8%;膜分离可基本保留菠萝汁中的营养成分,有效去除果汁中的大分子物质、微生物和部分色素,大大改善了菠萝汁的外观品质和微生物指标。     

A physicochemical investigation of membrane fouling in cold microfiltration of skim milk

The main challenge in microfiltration (MF) is membrane fouling, which leads to a significant decline in permeate flux and a change in membrane selectivity over time. This work aims to elucidate the mechanisms of membrane fouling in cold MF of skim milk by identifying and quantifying the proteins and minerals involved in external and internal membrane fouling. Microfiltration was conducted using a 1.4-μm ceramic membrane, at a temperature of 6 ± 1°C, cross-flow velocity of 6 m/s, and transmembrane pressure of 159 kPa, for 90 min. Internal and external foulants were extracted from a ceramic membrane both after a brief contact between the membrane and skim milk, to evaluate instantaneous adsorption of foulants, and after MF. Four foulant streams were collected: weakly attached external foulants, weakly attached internal foulants, strongly attached external foulants, and strongly attached internal foulants. Liquid chromatography coupled with tandem mass spectrometry analysis showed that all major milk proteins were present in all foulant streams. Proteins did appear to be the major cause of membrane fouling. Proteomics analysis of the foulants indicated elevated levels of serum proteins as compared with milk in the foulant fractions collected from the adsorption study. Caseins were preferentially introduced into the fouling layer during MF, when transmembrane pressure was applied, as confirmed both by proteomics and mineral analyses. The knowledge generated in this study advances the understanding of fouling mechanisms in cold MF of skim milk and can be used to identify solutions for minimizing membrane fouling and increasing the efficiency of milk MF.     

The effect of pre-treatment on the anthocyanin and flavonol content of black currant juice (Ribes nigrum L.) in concentration by reverse osmosis

Reverse osmosis process for the concentration of black currant juice was carried using AFC-99 tubular membrane at 30 °C and 45 bar. The contents of selected flavonols and anthocyanins were analyzed after centrifugation; enzyme treatment by Panzym Super E and by Rohapect berry followed by centrifugation; and ultrafiltration black currant juices and juice concentrates. The total soluble solid (TSS) content of the juices increased from the initial 17.6–17.9 °Brix to 24–24.8 °Brix in the case of the centrifuged juice in the concentration process. Similarly, it increased from 14.5–15.5 °Brix to 23.1–23.4 °Brix for the Panzym Super E treated juice, and from 16.1–16.9 °Brix to 22.5–23.1 °Brix for the Rohapect berry treated black currant juices. The ultrafiltered juice had the lowest initial TSS content between 14.1 and 14.9 °Brix and it increased to 22.1–23.1 °Brix. The average permeate fluxes during the concentration process were 7.3 L m⁻² h⁻¹ for the centrifuged juice, 11.9 L m⁻² h⁻¹ for the Panzym Super E treated juice, 9.2 and 13.1 L m⁻² h⁻¹ for the Rohapect berry treated and ultrafiltered juice, respectively. Analysis indicated that the enzymatic treatment resulted in the increase of anthocyanin and flavonol content of the juices. The centrifugation process decreased the amount of anthocyanins and flavonols to some extent. The juice clarified by ultrafiltration had significantly lower concentrations of anthocyanins and flavonols, while the juices treated by Panzym Super E had the highest levels of these flavonoids. This study recommends enzymatic pre-treatment by Panzym Super E, since it improves the permeate flux in reverse osmosis during the concentration process, and results in a juice concentrates highest in anthocyanins and flavonols.     

Storage quality of pineapple juice non-thermally pasteurized and clarified by microfiltration

Microfiltration (MF) is classified as a non-thermal process for the fruit juice industry. It could provide a better preservation of the phytochemical property and flavor of the juice. This work aimed to study the stability of phytochemical properties including vitamin C, total phenolic content, antioxidant capacity (2-Diphenly-1-picrylhydrazyl: DPPH, free radical scavenging capacity and Oxygen Radical Absorbance Capacity: ORAC assays), microbial and chemical–physical (color, browning index, pH and total soluble solid) properties of MF-clarified pineapple juice during storage at various temperatures (i.e. 4, 27, and 37 °C). The juices were clarified by microfiltration using hollow fiber module. The results showed that most of the phytochemical properties and soluble components were retained in the juice after microfiltration. No microbial growth was detected after 6 months of storage. The storage time and temperature did not affect total soluble solids and pH (P > 0.05). The color (L^*) of clarified juice stored at 4 °C was lighter than the juices stored at higher temperature levels (P < 0.05). The phytochemical properties and total phenol content of the juice significantly decreased as storage time and temperature increased (P < 0.05). Vitamin C content was the attribute that affected storage time and temperature most as indicated by reaction rate constant and activated energy. Storage of non-thermally pasteurized and clarified pineapple juice at 4 °C was the most suitable since it allowed the best quality preservation.