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BACKGROUND: Citrus juices can be cold‐concentrated by crossflow microfiltration (CMF) in order to obtain functional foods enriched in carotenoids, flavonoids and pectins. The work aimed to characterize the organoleptic quality of this type of micronutrient‐dense foods through their aroma profile and sensory analysis. Two citrus concentrates with and without a diafiltration step were compared. RESULTS: Both citrus products were very different, linked to aroma compound, sugar and organic acid contents. Due to its sugar/acidity balance and its better aromatic profile responsible for the citrus–floral flavour, the concentrate without diafiltration was preferred by the sensory panel. Thanks to a simple transfer model, we showed that retention of volatiles clearly varied from one aroma compound to another. The terpene hydrocarbons were the most retained by the membrane during CMF, probably because they were strongly associated with insoluble solids by adsorption. CONCLUSION: Even though the process modified their organoleptic profiles, both citrus‐based products were well rated and can be consumed directly as pleasant functional drinks. © 2022 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Abstract: Cashew apple fibrous residue is a by-product of the cashew juice industry. After pressing using a helical type continuous press followed by crossflow microfiltration, an aqueous extract was obtained from these cashew apple fibres. It was characterised by an intense yellow colour due to carotenoid pigments. Carotenoids were identified and quantified in the cashew apple before extraction, in its aqueous extract and in the concentrate obtained by microfiltration. Cashew apple aqueous extract and its concentrate presented a carotenoid profile with 11 carotenoids, most of them were tentatively identified by HPLC-DAD–MS and are xanthophylls present under an esterified form. Auroxanthin and β-cryptoxanthin represented around 50% of total carotenoids. Concentration of the extract by microfiltration led to epoxy-furanoxy rearrangement of violaxanthin and antheraxanthin. The process allowed an increase of 10 times total carotenoid content compared with initial cashew apple. Total carotenoid content of the final concentrated extract reached 54mg/kg. [Copyright &y& Elsevier]

The açai juice is an Amazonian product that has been exported to various countries around the world. Its main characteristic is the presence of antioxidant compounds especially anthocyanins. Nanofiltration is a membrane separation process that has the ability to separate compounds of low molar weight. Açai juice clarified by microfiltration was used as feed to evaluate nanofiltration membranes of different manufacturers regarding the permeate flux and the retention of anthocyanins. All the evaluated membranes were efficient in retaining the anthocyanins from the açai juice. NF 270 membrane, a composite membrane composed by a polyamide top layer and a polysulphone microporous support, presented the highest water permeability before and after the nanofiltration of açai juice. In addition, this membrane also presented the highest value of permeate flux in the nanofiltration process of açai juice as well as the anthocyanins retention above 99%. The effect of fouling for this membrane was approximately 28%. The observed results showed the potential of nanofiltration on the recovery of anthocyanins from açai fruit. [ABSTRACT FROM AUTHOR]

Crossflow microfiltration was implemented to enrich a clementine/pink grapefruit juice in carotenoids, flavonoids and pectins modulating its sugar content thanks to an added diafiltration step. Using tubular ceramic membrane with pore diameter of 0.2 μm at 30–40 °C, a crossflow velocity of 5 m‧s−1 and a transmembrane pressure of 2.6 bar, the impact of the process was assessed focusing on bioactive compounds and physical characteristics of the concentrates. With permeate flux above 30 kg‧h−1‧m−2, the process resulted in an increase of 8–10 times in the content of provitamin A carotenoids (33 mg‧kg−1 in the final products), lycopene (43 mg‧kg−1), hesperidin (3.2 g‧kg−1) and pectin (5.5 g‧kg−1) giving a unique and interesting composition profile. Moreover, diafiltration divided the sugar content by 3. This can be relevant for the product to be recommended as part of a reduced sugar diet for diabetic people. By modelling the retention of bioactive compounds, we showed that it was possible to modulate sugar, flavonoids, carotenoids and pectin contents in the concentrate that could be a key issue for the biological activity of this potential functional citrus-based food. • Modulation of citrus bioactive compounds through crossflow microfiltration. • A citrus-based food enriched 8-fold in carotenoids, flavonoids and pectins. • Diafitration allowed to divide by 3 sugar content of the citrus-based food. • Modelling useful to find operating conditions, for a targeted composition profile. [ABSTRACT FROM AUTHOR]

This work aimed to evaluate an eco-friendly process based on microfiltration with a diafiltration stage in order to concentrate and purify the main carotenoids and flavonoids in citrus juices. Pilot plant scale trial parameters were: tubular ceramic membranes with 0.2 μm pore diameter, 40 °C and 3 bar of transmembrane pressure. Different operating conditions were tested varying volumetric reduction ratio (VRR) from 2.5 to 10 and diavolume (DV) up to 1.7. Permeate flux ranged from 20 to 100 L h − 1 m − 2 according to the VRR. The concentration was multiplied by 5 to 10 for carotenoids and hesperidin but only by 2 to 3 for narirutin. Diafiltration increased the purity of carotenoids and hesperidin from 8 to 20 times. A model was validated for prediction of the concentration and purification factors vs. VRR and DV and the retentions were 100%, 97% and 63% for carotenoids, hesperidin and narirutin. [ABSTRACT FROM AUTHOR]

This work focused on an eco-friendly process to concentrate carotenoids from a citrus juice formulated with clementine and pink grapefruit. It is based on crossflow microfiltration associated with enzymatic liquefaction, diafiltration and pasteurization. The aim was to evaluate the impact of the main operating conditions on the process performance and on the nutritional quality of the final concentrate taking into account the bioaccessibility of β-carotene, β-cryptoxanthin and lycopene. First, the best enzyme/pressure/membrane combination was chosen in order to maximize permeate flux during microfiltration (>100 kg.h−1.m−2 at 2.6 bar with tubular inorganic membranes). Second thanks to a Plackett-Burman experimental design applied to the whole process, we showed the enzymatic dose was the most impacting parameter on carotenoid bioaccessibility and it decreased it. An optimal dose of enzyme had to be defined in order to obtain a good compromise between the process performance and the nutritional quality of the citrus concentrate. • Process combining enzyme liquefaction, microfiltration, diafiltration, pasteurization. • The most influential step on carotenoid bioaccessibility was the enzyme treatment. • Low enzymatic dose ensured high process performance without reducing bioaccessibility. • No correlation between particle size, viscosity and carotenoid bioaccessibility. • In optimal conditions, the whole process multiplied the bioaccessible carotenoid content by 4.8. [ABSTRACT FROM AUTHOR]

Abstract An integrated process coupling crossflow micro and ultra or nanofiltration was applied to separate the betacyanins in cactus pear juice (30 °C). Four microfiltration ceramic membranes (0.1–0.2 μm, 1.8–3.3 bar) and 4 ultra/nanofiltration organic membranes (0.2–4.0 kDa, 5–30 bar) were tested. Microfiltration was a first step to remove insoluble solids with low retention of soluble solids. By coupling with enzymatic liquefaction, permeate flux Jp was increased by 2 and the retention of betacyanins was limited. Ultra/nanofiltration was then used for solute separation. Retentions of solutes could be modulated by varying membrane/pressure combinations that favor rather the concentration of all the solutes or rather the purification of the betacyanins with respect to the total dry matter. Retention of individual betacyanins could be a little different which also made possible fractionation. Simulations using simple models allowed to evaluate the interest of the process for concentrating, purifying and fractionating betacyanins with a possible diafiltration step. Industrial relevance Betacyanins are natural colorants that can be obtained from cactus pear juice, a crop of increasing interest for its agricultural potential in Sahelian regions. The aim of this study was to evaluate a new integrated process based on membrane separation allowing to concentrate or separate betacyanins from other solutes at low temperature and with a limited environmental impact. This process associates a first step to clarify the cactus pear juice by microfiltration after enzymatic liquefaction and a second step to concentrate or purify betacyanins by ultra or nanofiltration. By choosing different membrane/transmembrane pressure combinations in the 2nd step, solute retentions could be modulated in order to favor rather the concentration of all solutes or rather the separation of betacyanins from total soluble solids or even rather the fractionation of betacyanins themselves. Highlights • Coupling micro and ultra/nanofiltration to separate betacyanins in cactus pear juice • Microfiltration with enzymatic liquefaction for clarifying with low solute retention • Ultra/nanofiltration for concentrating or purifying betacyanins • Separation pattern modulated thanks to different membrane/pressure combinations [ABSTRACT FROM AUTHOR]

The concentration of thermosensitive bioactive compounds remains an important challenge. A gentle integrated process including enzymatic maceration, crossflow microfiltration, diafiltration and centrifugation was applied to watermelon juice to obtain a natural extract enriched with lycopene. Microfiltration was performed using ceramic membranes with different pore diameters (0.2 to 1.4 μm), transmembrane pressures (50 to 200 kPa) and temperatures (50 °C and 60 °C). Using the best operating conditions during microfiltration, the permeate flux was close to 110 L·h − 1 ·m − 2 , and the lycopene concentration increased 11-fold in the retentate. Diafiltration allowed for the purification of lycopene up to 25-fold. Centrifugation enhanced the lycopene concentration up to 4-fold. cis -Isomerization remained low and similar to that of raw juice. This integrated process obtained a natural extract of lycopene that was 41 times more concentrated and 34 times purer than the initial juice, yielding an extract with up to 2% all- trans -lycopene on a dry basis. [ABSTRACT FROM AUTHOR]

Despite the several advantages of microfiltration, applications of this separation technique in fruit juice industries have been challenged by its low economical productivity due to membrane fouling. Although several studies aimed to identify operating conditions (e.g. juice pretreatment, crossflow filtration mode, etc.) to achieve acceptable performances, only few studies focused on the fouling propensity of fruit juices and on the identification of their foulant compounds. The aim of this work was to evaluate the fouling behavior of two orange juices and focused on the identification of relevant size-classes of foulant particles. Lab-scale filtration tests were carried out in conjunction with juice size-fractionation with the aim of quantifying the resistance to filtration of the juices. Based on a resistance-in-series approach, size-cartographies of foulant particles that are juice and membrane-specific were built. These cartographies were provided for two mineral membranes M 1.2 and M 0.2 with different average pore diameters (1.2 and 0.2 μm). M 1.2 results showed that the fouling is mainly external for both juices and due to particles larger than 2 µm. In contrast, results concerning M 0.2 filtration tests showed that four different size-classes of fruit juices compounds are involved in different fouling mechanisms. Moreover, the hydraulic reversibility of the fouling mechanisms was evaluated through the impact of shear rate on the measured resistances. It was seen that the fouling was mainly reversible when M 1.2 was used for both juices filtration while it was not the case when juices were filtered with M 0.2 . This information would be interesting to choose the appropriate strategy in order to enhance the microfiltration of these juices at large scale. Moreover, the proposed size-cartography strategy would greatly satisfy the industrial demand for practical tool to identify the different size-classes of compounds governing the overall membrane fouling. [ABSTRACT FROM AUTHOR]

Cross-flow microfiltration has replaced conventional fining methods for clarifying fruit juices, resulting in the combination of clarification and preservation in one single continuous operation. However the performance of this process is limited by the fouling mechanism during the filtration operation, related to the fruit juice fouling propensity. The aim of this work was to study the possibility of predicting the fruit juices filterability, according to some of their intrinsic characteristics. Therefore, 9 different commercial orange juices were chemically and physicochemically characterized (17 characterization parameters) and laboratory scale filtration tests, in an agitated and pressurized filtration module, were carried out at constant transmembrane pressure (1.5 bar). Fruit juices filterability was evaluated from the permeate flux evolution during the filtration operation. Partial Least Squares (PLS) method was particularly used for the analysis of relationship between the fruit juices filterability and the juice studied characteristics. PLS was initially performed using the whole set of predictor variables. The aim of this first analysis was to highlight the most important juice characteristics among the 17 studied ones; a simplified PLS model was performed using model-wise method and PLS–VIP method as important variable selection procedure. It was possible to predict satisfactorily ( R 2 > 0.9) fruit juices filterability according to only 5 physicochemical characteristics, reflecting the different phases of the studied juices (dry matter, total soluble solids, pH, conductivity, and surface area average diameter). [ABSTRACT FROM AUTHOR]

Abstract: In this study, roselle extract was cold sterilized by crossflow microfiltration. At laboratory scale the optimal operating conditions at volumetric reduction ratio (VRR) 1 cannot be generalized when VRR is greater than 1. Indeed, at VRR 1 the optimal transmembrane pressure was 2.5bar with a permeate flux of 185Lh−1 m−2, while at VRR 20 optimal pressure was 3.7bar with a permeate flux of 95Lh−1 m−2. A simple model that allowed to represent the effect of VRR and transmembrane pressure on the permeate flux was adjusted with the experiments done at laboratory scale. This model used to predict the permeate flux using a semi-industrial pilot scale equipment gave a good match between the experimental and calculated performances. Permeate was collected aseptically and stored at 4, 20 and 37°C for 90days. A roselle extract storage at 4 and 20°C was appropriate for consumption after a 3month shelf life. [Copyright &y& Elsevier]

This work aimed to further investigate microfiltration with diafiltration to obtain a rich carotenoid extract from the solid by-product of cashew apple (Anacardium occidentale L.) juice processing. This solid residue called cashew fibers is rich in bioactive compounds, especially carotenoids. After mixing with water and pressing, an aqueous suspension was obtained and processed by crossflow microfiltration (40 °C) using tubular ceramic membrane with 0.2 μm pore diameter. Permeate flux, which increased with transmembrane pressure, could be maintained above 100 L·h−1·m−2 at high volume reduction ratio by coupling mechanical extraction with enzyme liquefaction. The concentration step led to an increase of the carotenoid content by up to 19-fold and the diafiltration step allowed the carotenoid purity to be multiplied by 5. The impact of the process on the retentate characteristics was assessed using a model based on simple assumptions. This calculation tool can easily be implemented and is helpful for choosing the operating conditions, to minimize water consumption as well as effluent production. • Integrated extraction-filtration process of cashew fibers with enzyme liquefaction. • Total carotenoid retention during concentration and purification by microfiltration. • High permeate flux at a volume reduction ratio of up to 20. • Carotenoid purity multiplied by 5 using diafiltration. • Modelling to forecast purification rate minimizing effluent volume and water consumption. [ABSTRACT FROM AUTHOR]