Application of Cross-Flow Filtration Technique in Purification And

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Article Application of Cross-Flow Filtration Technique in Puriﬁcation and Concentration of Juice from Vietnamese Fruits

Huynh Cang Mai

Department of Chemical Engineering and Processing, Nong Lam University, Ho Chi Minh City 700000, Viet Nam; [email protected]

Academic Editor: Karen Smith Received: 1 July 2017; Accepted: 26 August 2017; Published: 4 September 2017

Abstract: This study is to offer a 1st insight in the use of membrane process for the purification and concentration of Vietnamese fruit juices: cashew apple (Anacardium occidentale Line.), dragon fruit (Cactus hémiépiphytes), pineapple (Ananas comosus), pomelo (Citrus grandis L.), and gac aril oil (Momordica cochinchinensis Spreng.). On a laboratory scale, the effect of different operating parameters such as trans-membrane pressures (TMP), temperature and membrane pore sizes on permeate flux was determined in order to optimize process conditions that would ensure acceptable flux with adequate juice quality. The quality of the samples coming from the ultrafiltration (UF) process was evaluated in terms of: total soluble solids (TSS), suspended solids (SS), and vitamin C. For example, the purification process of cashew apple juice by cross-flow filtration was optimized at 0.5 µm membrane pore size, 2.5 bars TMP, and 60 min filtration time. Besides, this technique was applied to enhance carotenoids concentration from gac oil. Optimum conditions for a high permeate flux and a good carotenoids retention are 5 nm, 2 bars, and 40 ◦C of membrane pore size, TMP, and temperature, respectively. Carotenoids were concentrated higher than that in feeding oil.

Keywords: cross-ﬂow ﬁltration; gac oil; cashew apple; dragon fruit; pineapple; pomelo

1. Introduction Membrane filtration is one of the widely used techniques in food industry (fruits juices clarification, protein standardization in dairy industry, fractionation of milk fat, beer filtration, and stabilization ... ). Cross flow filtration (also known as tangential flow filtration) is a filtration technique in which the starting solution passes tangentially along the surface of the filter. The application of crossflow ultrafiltration in clarification or concentration fruit juice has been studied on kiwi, orange, melon, cantaloupe, and umbu juice [1–5]. To our knowledge, this has not been studied and applied on processing of fruit juice in Vietnam. Cashew apple (Anacardium occidentale Line), a pseudo fruit, is a by-product of the cashew nut industry. Viet Nam produces more than 600.000–700.000 tons of cashew apple per year [6]. Although highly nutritious and full of vitamin C [7], most of Vietnam’s cashew apples are disposed at harvest and not utilized in the country. This study will highlight the opportunities for a processing of the cashew apple juice by ultrafiltration. Dragon fruit (Hylecereus polyhizus) is well known for its rich nutritional contents and is commercially available worldwide for improving many health problems. Its origin is from Central America and then it was introduced in Vietnam in the early twentieth century by the French. Dragon fruit is rich in nutritional values such as fibers, vitamin C, potassium, protein, fiber, sodium, calcium, and minerals [8]. It has relatively high antioxidant activity when compared to that of the other subtropical fruits. Mostly fleshed varieties are used for fresh consumption. Processed dragon

Beverages 2017, 3, 44; doi:10.3390/beverages3030044 www.mdpi.com/journal/beverages Beverages 2017, 3, 44 2 of 15 fruit products are rarely available in local markets and very little work has been done on processing of dragon fruit in Vietnam. Pineapple (Ananas comosus (L.) Merr), is the edible member of the Bromeliaceae family. Pineapple is known for its good aroma, flavor, juiciness, sweetness, and its various nutritional and health benefits, as it contains a considerable amount of calcium, potassium, fiber, vitamin C, phenolic, fiber, and minerals [9]. Moreover, pineapple is the best-known source of endopeptidase bromelain [10]. Pineapples can be consumed fresh or processed as condiments, sweets, savories, cakes, pastries, yoghurt, and punches. Clarification of pineapple juice by cross-flow filtration has not been done in Vietnam. Pomelo (Citrus grandis L.) is a subtropical citrus tree and also a very cultivated fruit in Vietnam. The total amount of pomelo production is 50.000 tons per year [11]. Pomelo has a high nutritional value to human health as it is rich in vitamin C and other mineral elements [12]. Gac (Momordica cochinchinensis Spreng.) fruit, a traditional fruit in Vietnam is extremely good for health. Oil extracted from gac aril has high content in carotenoids, mainly β-carotene and lycopene [13]. Carotenoids concentration and purification by cross-flow filtration has been simple than the conventional chemical process because of their advantages, such as low energy consumption, operation at mild temperatures, and the absence of addition of chemical products [14]. Membrane blockage (fouling) is major difficulty of the filtration process that needs to be controlled. This phenomenon is caused by different contributions, including polarization concentration, gel formation, particle adsorption, and pore blockage [15]. In the filtration process, the membrane pore size, temperature, and transmembrane pressure are important factors that need to be optimized in order to increase the filtration yield [16]. The application of membranes technology for tropical fruits processing in Vietnam has not been reported in literature. Using this technology to concentrate and purify the juice can improve the quality of products and increase economic value of Vietnamese fruits. The purpose of this study is to offer the 1st highlight of application of crossflow ultrafiltration on Vietnamese fruit juice processing. This work will study the impact of the operational conditions (transmembrane pressure, membrane pore size, and temperature) on permeate flux and quality of product. The resistance of process will be also analyzed.

2. Materials and Methods

2.1. Materials Fresh fruits (dragon fruit, pineapple, pomelo, and gac fruit) were purchased from Co.op Mart supermarket in Ho Chi Minh, Viet Nam. Cashew apple was purchased from Long Khanh, Dong Nai province. The maturity of fruits had to be controlled as these significantly affect the characteristics of juices. A ripe dragon fruit will have a bright and vibrant coloration and a smooth surface. It takes the dragon fruits about 50 days to reach maturity after flowering. The time from flowering to mature fruit is about 60–70 days, 190–210 days, 90–100 days, and 80–90 days for cashew apple, pomelo, pineapple, and gac fruit, respectively. Gac fruit itself becomes a dark orange color upon ripening, and is typically round or oblong, maturing to a size of about 13 cm in length and 10 cm in diameter. Its exterior skin is covered in small spines while its dark red interior consists of clusters of fleshy pulp and seeds. Fruits were manually washed in water and then peeled, obtaining the flesh of the fruit. Fruit juices were obtained by juice presses, model Panasonic MJ-DJ01S (Osaca, Japan). Gac aril oil was obtained by screw oil presses, model Anyang 6YL-68 (AGICO Co., Anyang, China). The juice and oil were pre-filtered by cloth and cellulose acetate membrane filter before the processing of ultrafiltration (UF). Cellulose acetate membrane was from Sartorious Company, Germany with 5 µm of membrane pore size. The antioxidant agent (Butylated Hydroxytoluene, BHT, 0.1% v/v) was added into the juice and oil before storage. The juice and oil were stored in the fridge (<10 ◦C) during the experiment. Chemical agents such as BHT, n-hexane, acetone, sodium hydroxide (NaOH), methanol, and other analytic reagents were purchased from Merck Ltd. and India supplied by Bach Khoa Chemical Company, 334 Tô Hien Thanh street, District 10, Ho Chi Minh City, Viet Nam. Beverages 2017, 3, 44 3 of 15 Beverages 2017, 3, 44 3 of 15

2.2.analytic Chemical reagents and Physical were Analysis purchased from Merck Ltd. and India supplied by Bach Khoa Chemical Company, 334 Tô Hien Thanh street, District 10, Ho Chi Minh City, Viet Nam. Physiochemical characterization of juice and oil (both of feeding and ﬁnal product) was evaluated by measuring2.2. Chemical their and viscosity, Physical Analysis pH, and their nutritional compositions (protein, carbohydrates, lipid, total solid content (TSC), total soluble solids (TSS), and total carotenoids content (TCC). The total carotenoid Physiochemical characterization of juice and oil (both of feeding and final product) was content (TCC) was measured using a Thermo Spectronic model Genesys 20 (Thermo Scientiﬁc, evaluated by measuring their viscosity, pH, and their nutritional compositions (protein, Waltham, MA, USA) at a wavelength of 473 nm following the procedure presented by Tran [17]. carbohydrates, lipid, total solid content (TSC), total soluble solids (TSS), and total carotenoids content Other parameters were measured by using methods as in Table1. (TCC). The total carotenoid content (TCC) was measured using a Thermo Spectronic model Genesys 20 (Thermo Scientific, Waltham, MA, USA) at a wavelength of 473 nm following the procedure Table 1. Method for physiochemical analysis. presented by Tran [17]. Other parameters were measured by using methods as in Table 1.

Parameter Method Table 1. Method for physiochemical analysis. pH Standard methods (AOAC, 1990) [18] TSCParameter Abbe refractometer (Atago Co., Tokyo, Japan)Method Acid indexpH ISOStandard 660:2009 methods [18] (AOAC, 1990) [18] PhospholipidsTSC ColorimetricAbbe refractometer method (Atago of Stewart Co., Tokyo, [19] Japan) ViscosityAcid index UsingISO 660:2009 capillary [18] viscometer according to the Hagen-Poiseuille law [18] GranulometryPhospholipids ParticuleColorimetric Size method Distribution of Stewart Analyzer [19] LA-920—Horiba (Horiba Scientific, Tokyo, Japan) ColorViscosity CIEUsing L*a*b* capillary with viscometer Minolta Chroma according Meter to the CR-400 Hagen (Konica,‐Poiseuille Minolta, law [18] USA) GranulometryTSS RefractometersParticule Size Distribution Atago HSR-500 Analyzer (Atago LA‐ Co.,920—Horiba Tokyo, Japan) (Horiba Scientific, Tokyo, Japan) CarbohydratesColor FAP/WHO,CIE L*a*b* with 1998 Minolta [18] Chroma Meter CR‐400 (Konica, Minolta, USA) ProteinTSS AOARefractometers C 945.01 [18 Atago] HSR‐500 (Atago Co., Tokyo, Japan) CarbohydrateCarbohydrates AOACFAP/WHO, 920.39 1998 [18 ][18] Protein UV/VISAOA C 945.01 Spectrophotometric [18] method using GenesysTM 20 Visible Spectrophotometer Turbidity Carbohydrate (ThermoAOAC 920.39 Fisher [18] Scientific, Waltham, MA, USA) UV/VIS Spectrophotometric method using GenesysTM 20 Visible Spectrophotometer Turbidity 2.3. Ultrafiltration Experimental(Thermo Fisher Setup Scientific, Waltham, MA, USA) 2.3.The Ultrafiltration filtration experiments Experimental were Setup carried out in a laboratory pilot unit (Figure1), equipped by: The filtration experiments were carried out in a laboratory pilot unit (Figure 1), equipped by: - A 10-liter stainless steel feed tank. - ‐ A feedA 10 pressure‐liter stainless pump, steel motor feed Luckytank. Pro MRS/4 water pump (flow range: 16.7 to 100 L/min) - ‐ A tubeA feed and pressure shell heat pump, exchanger motor Lucky circulated Pro MRS/4 with water water, pump this was (flow used range: to maintain16.7 to 100 the L/min) constant ‐ temperatureA tube and of shell the feedheat oil.exchanger circulated with water, this was used to maintain the constant temperature of the feed oil. 2 - 2 pressure gauges (0–10 kgf/cm , by graduation 0.2) located at the inlet (Pin) and outlet (Pout) of ‐ 2 pressure gauges (0–10 kgf/cm2, by graduation 0.2) located at the inlet (Pin) and outlet (Pout) of the membrane. the membrane. - ‐ OneOne ceramic ceramic membrane membrane (characteristics (characteristics of of these these membranes membranes are are presented presented in in Table Table2) 2) is setis set in in the filtrationthe filtration module module for each for experiment.each experiment.

8 9 10

1 7

5 4 3 2

FigureFigure 1. Filtration1. Filtration pilot pilot (1—Feed (1—Feed tank; 2—Feed 2—Feed removing removing valve; valve; 3—Feed 3—Feed pump; pump; 4—Inlet 4—Inlet valve; valve; 5— 5—InletInlet pressurepressure gauge;gauge; 6—Permeate6—Permeate exit; 7—Membrane; 7—Membrane; 8—Outlet 8—Outlet pressure pressure gauge; gauge; 9—Outlet 9—Outlet valve; valve; 10—Heat10—Heat exchanger). exchanger).

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Table 2. Characteristics of experimented ceramic membranes.

Type Ceramic Pore size 20 nm, 50 nm, 100 nm, 500 nm and 1000 nm Origin Pall Schumasiv, Belgium Composition ZrO2–TiO2 Filtration area (m2) 0.0055 (Outer/Inner) diameter (mm) 10/7 Length (mm) 250 Maximum pressure (kPa) 1500 Maximum temperature (◦C) 200

2.4. Filtration Processing In the filtration process, the solution that passes along the membrane surface and back to the feed reservoir is the retentate. Solution that passes across the membrane is the permeate. In this study, to clarify juices of cashew, apple, dragon fruit, pineapple, and pomelo, membrane process was used and the desired products were permeate. At the same time, the membrane process was also applied to concentrate the carotenoids and to eliminate the phospholipids and free fatty acid in gac oil, and as the result, the desired product was retentate. Filtration experiments were realized by two modes of operating: total recycle mode and batch concentration mode. In total recycle mode, permeate and retentate were totally recycled in the feed tank. This experiment is to determine optimal operating hydrodynamic condition. In batch mode, only retentate was recycled to feed tank. This process is to determine the filtration yield and product quality. This process is operated at the optimal conditions identified by total recycle model. The following parameters were used in filtration process:

• Permeate flux (J, L/h/m2): measures the volume (l) of permeate obtained on function of time (h) per filtration area (m2). • Coefficient of retention (R, %): measures the retention rate of determined solute by the membrane during filtration: C R = 100 × 1 − P (1) CF

where CP and CF are the concentration of the solute in permeate and feeding, presented in Kg/m3, respectively.

• Transmembrane pressure (TMP,bar): The total hydraulic resistance corresponds RT = RM + RP + RF, where RM, RP, RF is membrane resistance, concentration polarization resistance and fouling resistance, respectively. These three parameters were evaluated experimentally.

3. Statistical Analysis Each of experiments was carried out in triplicate. All of the data were examined for the analysis of variance (ANOVA) and regression models using Statgraphics v.7.0 (Statpoint Technologies, Inc., Warrenton, VA, USA). Multiples range test and LSD (Least Signiﬁcant Differences) were used for comparing means in an analysis of variance. All the statistical tests were realized with a conﬁdence interval of 95% (p < 0.05).

4. Results and Discussion

4.1. Fruit Juice Clariﬁcation

4.1.1. Effect of Membrane Pore Size on Permeate Flux and Turbidity of Juice The effect of membrane pore size, transmembrane pressure, and the temperature on the permeate ﬂux was carried out according to the total recycle mode. In Figures2–13, the effects of these parameters BeveragesBeverages2017 2017, 3, ,3 44, 44 55 of of 15 15

parametersBeverages 2017 on, 3 , the44 permeate flux, in the UF treatment of cashew apple, dragon fruit, pomelo5 of ,15 and onpineapple the permeate juice are flux, reported. in the UF treatment of cashew apple, dragon fruit, pomelo, and pineapple juice areparameters reported.Figures 2on–5 theshow permeate the permeate flux, in theflux UF decline treatment curves of cashew during apple, UF processing dragon fruit, of pomelo,cashew andapple, dragonpineappleFigures fruit,2 –juice 5pomelo show are reported. the, and permeate pineapple flux declinejuice in curveswhich duringtemperature UF processing and TMP of cashewwere maintained apple, dragon at a fruit,constant pomelo,Figures value and 2–5(30 pineapple °Cshow and the 2 juicebars, permeate inrespectively) which flux temperature decline while curves the and membrane during TMP were UF pore processing maintained size was of at changedcashew a constant apple,(100 value nm, (30500dragon◦ Cnm and and fruit, 2 1000 bars, pomelo, nm). respectively) Results and pineapple show while that thejuice permeates membrane in which flux temperature pore increase size was wit andh changed membrane TMP were (100 poremaintained nm, size. 500 Permeate nm at anda constant value 0(3 °C and 2 bars, respectively) while the membrane pore size was changed (100 nm, 1000flux nm).value Results obtained show of dragon that permeates fruit juice flux is relative increasely with smaller membrane due to its pore high size. viscosity. Permeate The flux permeate value 500 nm and 1000 nm). Results show that permeates flux increase with membrane pore size. Permeate obtainedflux during of dragon the filtration fruit juice decreases is relatively rapidly smaller at duethe initial to its high stage viscosity. (from 15 The to permeate 25%) and flux gradually during flux value obtained of dragon fruit juice is relatively smaller due to its high viscosity. The permeate thethereafter filtration (more decreases than rapidly40%). Rapid at the flux initial decline stage is (from attributed 15 to 25%)to the and growth gradually of a polarized thereafter layer (more during than flux during the filtration decreases rapidly at the initial stage (from 15 to 25%) and gradually 40%).thethereafter first Rapid stage (more flux and decline than fouling 40%). is deposition attributed Rapid flux to indecline thethe growthsecond is attributed ofstage. a polarized to This the growthis in layer agreement of during a polarized thewith firstlayer the stage duringresults and of foulingpreviousthe first deposition studies stage and [ in20, thefouling21] secondthat deposition showed stage. Thisthe in permeatethe is in second agreement flux stage. change with This the isover in results agreementmembrane of previous with pore the studiessize. results It [is20 ofwell,21 ]- thatknownprevious showed that studies thethe permeatemembrane [20,21] fluxthat pore changeshowed size overisthe one permeate membrane of the fluximportant pore change size. impactover It is membrane well-knowns on membrane pore that size. thefouling. It membrane is well Many‐ poreresearchesknown size is that explain one the of membrane thethat important the influence pore impacts size of is membrane one on of membrane the poreimportant size fouling. on impacts the Many permeate on researchesmembrane flux is attributedfouling. explain Many that via the the influencechangeresearches of of fouling membrane explain resistance. that pore the size influence on the of permeate membrane flux pore is attributedsize on the viapermeate the change flux is of attributed fouling resistance. via the changeTheThe turbidityturbi of foulingdity ofof resistance. permeate varies varies with with membrane membrane pore pore size size (Table (Table 3).3). Membrane Membrane pore pore size size of of500 500nm nmis highly isThe highly turbidity recommended recommended of permeate for for variesthe the juice with juice clarification membrane clarification objective.pore objective. size (Table The The e 3).ffect effect Membrane of ofmembrane membrane pore size pore pore of size 500 size on onmajor majornm isnutritional highly nutritional recommended components components for of theofeach each juice kind kind clarification of ofjuice juice need objective. needss to tobe beThe exa examined meffectined of in membrane infurther further study. pore study. size on major nutritional components of each kind of juice needs to be examined in further study. Permeate flux of cashew apple on time 600 Permeate flux of cashew apple on time 600 1000 nm 500 nm 100 nm 1000 nm 500 nm 100 nm 400 400

L/h/m2) 200

( J, J, ( Flux Flux 00 0020 2040608010012040 60 80 100 120 TimeTime (min) (min) FigureFigureFigure 2. 2.Permeate 2.Permeate Permeate ﬂux flux flux of of of cashew cashew cashew apple apple apple juice juice on on time timetime withwith with different different membrane membrane membrane pore pore pore sizes sizes size (Ts ( T=(T 30= = 30 °C;30◦ °CC;; transmembranetransmembranetransmembrane pressure pressure pressure (TMP) ( TMP(TMP)) = = = 2 2 2 bars). bars).bars).

PermeatePermeate flux of dragondragon fruit fruit juice juice on on time time 600600 10001000 nm nm 500500 nm nm 100100 nm nm

400400

200 L/h/m2) 200 L/h/m2) ( J,

( J,

Flux 0 Flux Flux 0 0 20406080100120 0 20 40 Time60 (min) 80 100 120 Time (min) FigureFigure 3. Permeate 3. Permeate ﬂux flux of of dragon dragon fruit fruit juice juice on on time time withwith different membrane membrane pore pore sizes sizes (T ( T= 30= 30°C;◦ C; Figure 3. Permeate flux of dragon fruit juice on time with different membrane pore sizes (T = 30 °C; TMPTMP = 2 = bars). 2 bars). TMP = 2 bars).

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PermeatePermeate flux flux of of pomelo pomelo juice juice on on time time 600600 10001000 nm nm 500500 nm nm 100100 nm nm

400400 L/h/m2) L/h/m2) 200200 Flux (J, Flux (J,

00 00 2020 4040 6060 8080 100100 120120 TimeTime (min) (min) FigureFigure 4. 4. Permeate PermeatePermeate flux flux ﬂux of of of pomelo pomelo pomelo juice juice juice on on ontime time time with with with different different different membrane membrane membrane pore pore pore sizes sizes sizes ( T(T = = 3 (3T00 °C =°C 30; ;TMP TMP◦C; TMP== 2 2 bars). bars). = 2 bars).

PermeatePermeate flux flux of of pineapple pineapple juice juice on on time time 600600 10001000 nm nm 500500 nm nm 100100 nm nm

400400

L/h/m2) 200 L/h/m2) 200 J , J , Flux ( Flux Flux ( Flux 00 00 2020 4040 6060 8080 100100 120120 TimeTime (min) (min) Figure 5. Permeate flux of pineapple juice on time with different membrane pore sizes (T = 30 °C; FigureFigure 5.5. PermeatePermeate ﬂuxflux ofof pineapplepineapple juicejuice onon timetime withwith differentdifferent membranemembrane porepore sizessizes ((TT= = 3030 ◦°CC;; TMP = 2 bars). TMPTMP = = 22 bars).bars).

Table 3. Effect of membrane pore size on turbidity of juice. TableTable 3. 3.Effect Effect ofof membranemembrane pore pore size size on on turbidity turbidity of of juice. juice. MembraneMembrane Pore Pore Size Size (nm) (nm) CashewCashew Apple Apple Juice Juice DragonDragon Fruit Fruit Juice Juice PomeloPomelo Juice Juice PineapplePineapple Juice Juice Membrane Pore100100 Size (nm) Cashew0.2540.254 Apple ± ± 0.0 0.0 Juice11 a a Dragon0.3450.345 Fruit ± ± 0.0Juice 0.022 a a Pomelo0.3370.337 Juice± ± 0.01 0.0155 a a Pineapple0.2360.236 ± ± 0.0 0.0 Juice22 a a b b b a 100500500 0.2540.3480.348± ± 0.01± 0.01 0.01a22 b 0.3450.4200.420± 0.02 ± ± 0.02 0.02a 22 b 0.3370.2580.258± 0.015 ± ± 0.0 0.0a11 b 0.2360.2250.225± ± ±0.02 0.0 0.022a a c c c b 10005001000 0.3480.7520.752± ±0.012 ± 0.02 0.025b5 c 0.4200.8430.843± 0.022 ± ± 0.03 0.03b 33 c 0.2580.657±0.657±± 0.01 0.0 0.0b33 c 0.2250.7200.720± ± ±0.02 0.0 0.033 a b c c c b DifferentDifferent1000 letter letter superscripts superscripts 0.752show show± significant significant0.025 differences differences0.843 ± 0.033 among among the the men men0.657 values values± 0.03 in in the the same same0.720 column. column.± 0.03 Different letter superscripts show significant differences among the men values in the same column. 44.1.2..1.2. Effect Effect of of Transmembrane Transmembrane Pressure Pressure (TPM) (TPM) on on Permeate Permeate Flux Flux and and Turbidity Turbidity of of J Juiceuice 4.1.2. Effect of Transmembrane Pressure (TPM) on Permeate Flux and Turbidity of Juice FigureFiguress 66––99 indicateindicate thatthat thethe permeatepermeate fluxflux increasesincreases withwith TMPTMP upup toto aa limitinglimiting valuevalue whichwhich dependsdependsFigures on on the6 the–9 physical indicatephysical properties thatproperties the permeate of of the the suspension suspension flux increases. .The The withpermeate permeate TMP flux flux up tovalues values a limiting at at initial initial value conditions conditions which (withdepends(with purepure on water)water) the physical asas compacompa propertiesredred withwith of the the applied suspension.applied TMPTMP The werewere permeate alsoalso evaluated.evaluated. flux values ResultsResults at initial showshow conditions thatthat anyany (withincreaseincrease pure inin water)TMPTMP doesdoes as compared notnot bringbring with anyany beneficial thebeneficial applied effecteffect TMP onon were productionproduction also evaluated. raterate, , becausebecause Results excessiveexcessive show that energyenergy any inputincreaseinput doesdoes in TMP notnot does helphelp not toto bring increaseincrease any beneficial inin productionproduction effect on rate,rate, production membranemembrane rate, fouling becausefouling becomes excessivebecomes energyincreasinglyincreasingly input importantdoesimportant not help, , andand to the increasethe fluxflux decline indecline production isis accelerated.accelerated. rate, membrane ThisThis resultresult fouling isis inin becomes accordanceaccordance increasingly withwith membranemembrane important, theorytheory and, , andtheand fluxwith with decline further further isreport report accelerated.ss of of Kartika, Kartika, This Cassano resultCassano is and inand accordance Ushikubo Ushikubo [ with[1,1,55,22,22 membrane]]. .The The viscosity viscosity theory, of of dragon anddragon with fruit fruit further juice juice isreportsis muchmuch of higherhigher Kartika, thanthan Cassano thatthat of andof otherother Ushikubo fruitsfruits, , [ 1causecause,5,22s].s a Thea hihigher viscositygher pressurepressure of dragon demanddemand fruit for juicefor UFUF is process. muchprocess. higher TheThe reasonablethanreasonable that of pressure otherpressure fruits, for for UF causesUF processing processing a higher of of pressure cashew cashew demandapple, apple, dragon dragon for UF fruit, process.fruit, pomelo pomelo The, reasonable ,and and pineapple pineapple pressure juice juice for is is 1.5UF1.5 bars, processingbars, 3 3 bars, bars, of 1.5 1.5 cashew bars bars, ,and and apple, 2 2 bars, bars, dragon respectively. respectively. fruit, pomelo, The The impact andimpact pineapple of of TMP TMP on juiceon turbidity turbidity is 1.5 bars, of of permeate permeate 3 bars, 1.5 is is bars,also also remarkedandremarked 2 bars, ( (TableTable respectively. 4) 4). .A A higher higher The TMP TMP impact cause cause ofss TMPa a fouling fouling on turbidity and and has has occurred ofoccurred permeate more more is intensively. intensively. also remarked This This (Tablecake cake can 4can). Abebe higherconsidered considered TMP as causesas the the 2nd 2nd a fouling membrane membrane and has filtration. filtration. occurred more intensively. This cake can be considered as the 2nd membrane filtration.

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EffectEffect ofof TMPTMP onon fluxflux permeatepermeate ofof cashewcashew appleapple juicejuice 20002000

500500 nmnm 15001500 WaterWater 500500 nmnm

10001000

500500 Flux (J, Flux (J, L/h/m2) Flux (J, Flux (J, L/h/m2) Flux (J, Flux (J, L/h/m2) 00 00 0.50.5 11 1.51.5 22 2.52.5 33 3.53.5 44 4.54.5 55 TMP (bar) TMPTMP (bar(bar)) Figure 6. Effect of TMP on flux permeate of cashew apple juice (T = 30 °C; membrane = 500 nm). FigureFigureFigure 6. 6.6.Effect EffectEffect of ofof TMP TMPTMP on onon ﬂux fluxflux permeate permeatepermeate of ofof cashew cashewcashew apple appleapple juice juicejuice ( T ((TT= == 30 3300◦ °CC;°C;;membrane membranemembrane= == 500 505000 nm). nnm).m).

EffectEffect ofof TMPTMP onon permeatepermeate fluxflux ofof dragondragon fruitfruit juicejuice 20002000 10001000 nmnm WaterWater 10001000 nmnm 15001500 ) ) ) 10001000 h/m2 / h/m2 h/m2 / /

500500 Flux (J, L Flux (J, L Flux (J, L

00 00 0.50.5 11 1.51.5 22 2.52.5 33 3.53.5 44 4.54.5 55 TMP (bar) TMPTMP ((barbar)) ◦ FigureFigureFigure 7. 7.7.Effect EffectEffect of ofof TMP TMPTMP on onon permeate permeatepermeate ﬂux fluxflux of ofof dragon dragondragon fruit fruitfruit juice juicejuice ( T ((TT= == 30 3300 °CC;°C;;membrane membranemembrane= == 1000 10010000 nm). nnm).m).

EffectEffect ofof TMPTMP onon permeatepermeate ofof pomelopomelo juicejuice 20002000 500500 nmnm WaterWater 500500 nmnm 15001500

10001000 L/h/m2) L/h/m2) L/h/m2) J , J , J , 500500 Flux ( Flux Flux ( Flux Flux ( Flux

00 00 0.50.5 11 1.51.5 22 2.52.5 33 3.53.5 44 4.54.5 55 TMPTMP ((barbar))

Figure 8. Effect of TMP on permeate ﬂux of pomelo juice (T = 30 ◦C; membrane = 500 nm). FigureFigure 8.8. EffectEffect ofof TMPTMP onon permeatepermeate fluxflux ofof pomelopomelo juicejuice ((TT == 3300 °C°C;; membranemembrane == 505000 nnm)m)..

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Effect of TMP on permeate flux of pineapple juice 2000 Effect of TMP on permeate flux of pineapple juice 2000 500 nm 500 nm Water 500 nm 1500 Water 500 nm 1500

10001000 L/h/m2) L/h/m2)

, 500

J , 500 J (

Flux Flux ( Flux 0 0 000.511.522.533.544.550.5 1 1.5 2 2.5 3 3.5 4 4.5 5 TMP (bar) TMP (bar) ◦ FigureFigureFigure 9. 9.Effect 9.Effect Effect of of TMPof TMP TMP on on on permeate permeate permeate ﬂux fluxflux of of pineapple pineapple juice juice juice ( T(T = =30 30 3 0°C; °CC; membrane;membrane membrane = =500 = 50050 nm).0 nm).nm) .

Table 4. Effect of transmembrane pressure on turbidity of permeate. TableTable 4. 4.Effect Effect ofof transmembranetransmembrane pressure pressure on on turbidity turbidity of of permeate. permeate. Transmembrane Pressure (Bar) Cashew Apple Juice Dragon Fruit Juice Pomelo Juice Pineapple Juice Transmembrane Pressure (Bar) Cashew Apple Juice Dragon Fruit Juice Pomelo Juice Pineapple Juice Transmembrane Pressure0.5 (Bar) Cashew0.392 Apple ± 0.02 Juice a Dragon FruitND Juice Pomelo0.328 ±0.02 Juice a 0.299 Pineapple ± 0.01 Juice a a a a 0.50.5 1 0.3920.3920.387± ± ±0.02 0.00.012a a 1.155ND ±ND 0.042 a 0.3280.2870.328± ±0.02 0.01 ±0.0a b2 0.2550.2990.29 ± ±0.0159 ±0.01 0.0 b a1 a a b b 11 1.5 0.3870.3870.352± ± ±0.01 0.00.011a b 1.1551.155±ND0.042 ± 0.04 a 2 0.2870.2550.287± ±0.01 0.04± 0.0b b1 0.2600.2550.255 ±± 0.01 ±0.015 0.01 b b5 b b b 1.51.5 2 0.3520.3520.348± ±0.01 0.0250.01 b b 0.843ND ±ND 0.025 b 0.2550.2580.255± ±0.04 0.01± 0.0 b4 b 0.2250.2600.260 ±± 0.05 ±0.01 0.0 c 1 b b b b c 22 2.5 0.3480.3480.336± ± 0.025 ±0.02 0.025 bb 0.8430.843±ND0.025 ± 0.02 5 b 0.2580.2500.258± ± 0.010.015 ± 0.0 b1 b 0.2100.2250.225 ±± 0.02 ±0.05 0.0 c 5 c 2.5 ± b ND ± b 0.210 ± 0.02 c 2.5 3 0.3360.336 ND±0.02 0.0 2 b 0.822 ND± 0.03 b 0.2500.250ND0.015 ± 0.015 b 0.210ND ± 0.02 c 3 ND 0.822 ± 0.03 b ND ND 3 4 NDND 0.7560.822 ± ± 0.04 0.03 c b NDND NDND 4 ND 0.756 ± 0.04 c ND ND c c 54 5 NDNDND 0.7220.7220.756± ±0.02 ± 0.02 0.0c 4 NDNDND ND NDND 5 ND 0.722 ± 0.02 c ND ND ND:ND: not not detected. detected.Different Different letter letter superscripts superscripts show show significant significant differences differences among among the men the values men in values the same in the column same. ND:column. not detected. Different letter superscripts show significant differences among the men values in 4.1.3.the Effect same of column. Temperature on Permeate Flux 4.1.3. Effect of Temperature on Permeate Flux Figures 10–13 show the impact of temperature on flux of permeate. The viscosity of juice varies 4.1.3. EffectFigures of T10–13emperature show the on impact Permeate of temperature Flux on flux of permeate. The viscosity of juice varies with operating temperature. At a higher temperature, a reduction of the feed viscosity and an increase withFig ureoperatings 10–1 3temperature. show the impact At a ofhigher temperature temperature, on flux a reductionof permeate. of the The feed viscosity viscosity of juice and variesan of diffusion coefficients of macromolecules were noticed. The effect of these two factors helps to withincrease operating of diffusion temperature. coefficients At ofa macromoleculeshigher temperature were ,noticed. a reduction The effect of theof these feed two viscosity factors helpsand an enhance mass transfer and then increase the permeate flux. These two factors result in an increase increaseto enhance of diffusion mass transfer coefficients and then of macromolecules increase the permeate were flux.noticed These. The two effect factors of these result two in an factors increase helps of massof mass transfer transfer and and permeate permeate flux flux [2 [2].]. The The membrane membrane fouling at at a a higher higher operating operating temperature temperature to enhance mass transfer and then increase the permeate flux. These two factors result in an increase occursoccurs relatively relatively slower slower than than that that at at lower lower temperature. temperature. IncreasingIncreasing temperature temperature also also influences influences the the of mass transfer and permeate flux [2]. The membrane fouling at a higher operating temperature destructiondestruction and/or and/or oxidation oxidation of of the the heat-sensitive heat‐sensitive components in in the the juice, juice, such such as as vitamin vitamin C Cand and occurs relatively slower than that at lower temperature. Increasing temperature also influences the carotenoids.carotenoids. The The optimum optimum temperature temperature for for UF UF processing processing of cashew apple, apple, dragon dragon fruit, fruit, pomelo, pomelo, and and destruction and/or oxidation of the heat-sensitive components in the juice, such as vitamin C and pineapplepineapple juice juice is 50 is 50◦C, °C, 40 40◦C, °C, 50 50◦ C,°C, and and 50 50◦ °C,C, respectively.respectively. carotenoids. The optimum temperature for UF processing of cashew apple, dragon fruit, pomelo, and pineapple juice is 50 °C, 40 °CEffect, 50 of°C temperature, and 50 °C on, respectively. permeate flux of cashew apple juice 600 Effect of temperature on permeate flux of cashew apple 30C 40C 50C 500 juice 600 400 500 30C 40C 50C 300

400L/h/m2)

J 200 ( 300 100 Flux L/h/m2)

J , 200 0 0 20406080100120

Flux ( Flux 100 Time (min) 0 Figure 10. Effect of temperature0 on permeate20 flux40 of cashew60 apple juice80 (TMP=100 1.5 bars; membrane120 = 500 nm). Time (min)

Beverages 2017, 3, 44 9 of 15 BeveragesBeverages 2017 2017, 3, ,3 44, 44 9 9of of 15 15 Figure 10. Effect of temperature on permeate flux of cashew apple juice (TMP= 1.5 bars; membrane = FigureFigure 10. 10. Effect Effect of of temperature temperature on on permeate permeate flux flux of of cashew cashew apple apple juice juice (TMP= (TMP= 1.5 1.5 bars; bars; membrane membrane = = Beverages 2017500 ,nm).3, 44 9 of 15 500500 nm). nm). Effect of temperature on permeate flux of dragon fruit Effect of temperature on permeate flux of dragon fruit Effect of temperature on juicepermeate flux of dragon fruit 600 juice 600600 juice 30C 40C 50C 500 30C 40C 50C 500500 30C 40C 50C 400 400400 300 300300 L/h/m2)

, L/h/m2)

L/h/m2) J , 200

( ,

J 200 ( J 200

(

Flux 100

Flux 100 0 0 0 0 20406080100120 0 20406080100120 0 20406080100120Time (min) Time (min) Time (min) Figure 11. Effect of temperature on permeate flux of dragon fruit juice (TMP = 3 bars; membrane = FigureFigure 11. 11. Effect Effect of of temperature temperature on on permeate permeate flux flux of of dragon dragon fruit fruit juice juice (TMP (TMP = = 3 3 bars; bars; membrane membrane = = Figure1000 11. nm).Effect of temperature on permeate flux of dragon fruit juice (TMP = 3 bars; membrane = 1000 nm). 10001000 nm). nm). Effect of temperature on permeate flux of pomelo juice EffectEffect of of temperature temperature on on permeate permeate flux flux of of pomelo pomelo juice juice 600 600600 30C 40C 50C 500 30C30C 40C40C 50C50C 500500 400 400400 300 300 L/h/m2) 300

, L/h/m2)

L/h/m2) J ,

( , 200

J ( J 200

( 200

Flux 100 Flux Flux 100100 0 0 0 0 20406080100120 0 20406080100120Time (min) 0 20406080100120Time (min) Time (min) Figure 12. Effect of temperature on permeate flux of pomelo juice (TMP = 1.5 bars; membrane = 500 nm). FigureFigureFigure 12. 12. 12.Effect Effect Effect of of of temperature temperature temperature onon on permeate permeate flux flux flux of ofof pomelo pomelo juice juice juice (TMP (TMP (TMP = = 1.5 = 1.5 1.5 bars; bars; bars; membrane membrane membrane = =500 500 = nm). 500 nm). nm) . Effect of temperature on permeate flux of pineapple juice EffectEffect of of temperature temperature on on permeate permeate flux flux of of pineapple pineapple juice juice 600 600 600 30C 40C 50C 500 30C30C 40C40C 50C50C 500500 400 400400 300 300300 L/h/m2)

, L/h/m2)

L/h/m2) J , 200 ( ,

J 200 ( J

200 (

Flux 100

Flux 100 Flux 100 0 0 0 0 20406080100120 00 20406080100120 20406080100120Time (min) Time (min) Time (min) Figure 13. Effect of temperature on permeate flux of pineapple juice (TMP = 2 bars; membrane = 500 nm). FigureFigureFigure 13. 13. 13.Effect Effect Effect of of of temperature temperature temperature on on on permeatepermeate permeate flux flux of of of pineapple pineapplepineapple juice juice (TMP (TMP (TMP = = 2 = 2 bars; 2bars; bars; membrane membrane membrane = = 500 500 = 500nm). nm). nm).

4.2.4.2. Gac Gac Oil Oil Concentration Concentration 4.2.4.2. Gac Gac Oil Oil Concentration Concentration 4.2.1.4.2.1. Effect Effect of of Membrane Membrane Pore Pore Size Size on on Permeate Permeate Flux Flux and and Coefficient Coefficient of of Retention Retention of of TCC TCC in in Retentate Retentate 4.2.1.4.2.1. Effect Effect of Membraneof Membrane Pore Pore Size Size on on Permeate Permeate Flux and and Coefficient Coefficient of of Retention Retention of TCC of TCC in Retentate in Retentate Figure 14 shows the permeate flux decline curves during gac fruit oil filtration, which is FigureFigure 1414 showsshows thethe permeatepermeate fluxflux declinedecline curvescurves duringduring gacgac fruitfruit oiloil filtration,filtration, whichwhich isis increasedFigure 14 with shows membrane the permeate pore size. flux The decline effect curves of membrane during gacpore fruit size oil on filtration, the coefficient which of is retention increased increasedincreased with with membrane membrane pore pore size. size. The The effect effect of of membrane membrane pore pore size size on on the the coefficient coefficient of of retention retention with membrane pore size. The effect of membrane pore size on the coefficient of retention of TCC is presented in Table5. Coefficient of retention of TCC decreases when membrane pore size increases. Membrane pore size of 50 nm is acceptable as its high permeate flux and high coefficient of retention of TCC. Beverages 2017, 3, 44 10 of 15

of TCC is presented in Table 5. Coefficient of retention of TCC decreases when membrane pore size

Beveragesincreases.2017, 3, 44Membrane pore size of 50 nm is acceptable as its high permeate flux and high coefficient10 of 15 of retention of TCC.

Permeate flux of gac oil on time with different membrane pore size 25 100 nm 50 nm 20 nm

15 L/h/m2)

10 , J (

5 Flux

0 0 20406080100120 Time (min)

FigureFigure 14. Permeate14. Permeate flux flux of gacof gac oil oil on on time time with with different different membrane membrane pore sizes ( (TT == 30 30 °C;◦C; TMP TMP = 2 = bars). 2 bars).

Table 5. Effect of membrane pore size on coefficient of retention of TCC in retentate. Table 5. Effect of membrane pore size on coefficient of retention of TCC in retentate. Membrane Pore Size (nm) Coefficient of Retention of Carotenoids (%) Membrane Pore Size100 (nm) Coefficient15 of ± Retention 0.05 a of Carotenoids (%) 50 80 ± 3.5 b 100 15 ± 0.05 a 20 88 ± 2.2 c 50 80 ± 3.5 b Different letter20 superscripts show significant differences among the men 88 ± values2.2 c in the same column. Different letter superscripts show significant differences among the men values in the same column. 4.2.2. Effect of Transmembrane Pressure on Permeate Flux and Coefficient of Retention of TCC in Retentate 4.2.2. Effect of Transmembrane Pressure on Permeate Flux and Coefficient of Retention of TCC in RetentateFigure 15 shows the permeate flux values at a steady state (10 first min) versus TMP different. As TMP is driving force of a filtration process, its increase leads to a higher permeate flow rate Figure 15 shows the permeate flux values at a steady state (10 first min) versus TMP different. through the membrane. Generally, at stable operating conditions, permeate flux increases with TMP As TMP is driving force of a filtration process, its increase leads to a higher permeate flow rate through until a threshold, then since this is the peak value, it becomes relatively stable or decreases slightly. the membrane.This TMP limiting Generally, depends at stable on the operating physical properties conditions, of the permeate oil feed fluxand flow increases rate of with feed. TMP This result until a threshold,is according then since with this membrane is the peak theory value, and it becomeswith previous relatively reports stable [1,5,22]. or decreases Change slightly. of the retention This TMP limitingcoefficient depends of onTCC the with physical TMP propertiesis presented of in the Table oil feed 6. Results and flow show rate that of feed. the retention This result coefficient is according of withTCC membrane is related theory to TMP. and TMP with at previous three bars reports is applied [1,5 ,for22]. further Change experiments. of the retention coefficient of TCC with TMP is presented in Table6. Results show that the retention coefficient of TCC is related to TMP. TMPBeverages at three Table2017 bars, 3 ,6. 44 isEffect applied of TMP for on further coefficient experiments. of retention of total carotenoids content (TCC) in retentate. 11 of 15 Transmembrane Pressure (bar) Coefficient of Retention of Carotenoids (%) Effect of transmembrane pressure on permeate flux of 1 84 ± 2.6 a 400 gac oil 2 50 nm 85 ± 2.5 a 3 Water 50 nm 90 ± 3.6 b 300 4 92 ± 3.5 c 5 95 ± 3.2 d 200 Different letter superscripts show significant differences among the mean values in the same column. L/H/M2)

, J ( 100 FLUX 0 012345 TMP (BAR) FigureFigure 15. Effect15. Effect of transmembrane of transmembrane pressure pressure on on permeate permeate ﬂux flux of of gacgac oiloil (T = 30 °C;◦C; Membrane Membrane pore pore size = 100 nm). size = 100 nm). 4.2.3. Effect of Temperature on Permeate Flux and Coefficient of Retention of TCC in Retentate Generally, an increase of temperature results in an increase of permeate flux caused by a decrease of viscosity of oil feed (Figure 16). This phenomenon can be attributed to a reduction of feed viscosity and to an increase of the diffusion coefficient of macromolecules. The effect of these two factors is to enhance mass transfer and to increase permeate flux [1]. The results in Table 7 show that the change of temperature has an inversely proportional effect of coefficient of retention of TCC. The temperature might also reduce phospholipids micelle size in solution because the molecules of phospholipids did not aggregate together at high temperatures [23] that lead to pass through the membrane quickly and to minimize the fouling deposition. Through this experiment result, the maintenance of temperature at 40 °C is highly recommended for the gac oil filtration process because of its high flux permeates and relatively high effective retention of TCC.

Table 7. Effect of temperature on retention coefficient of TCC in retentate.

Temperature (°C) Retention Coefficient of TCC 30 95 ± 3.8 a 40 90 ± 3.6 b 50 88 ± 3.0 c Different letter superscripts show significant differences among the men values in the same column.

40 Effect of temperature on permeate flux of gac oil 30C 40C 30

20 L/h/m2)

, J ( 10 Flux

0 0 20406080100120 Time (min) Figure 16. Effect of temperature on permeate flux of gac oil (TMP = 3 bars; Membrane pore size = 100 nm).

4.3. Resistance Analysis

Table 8 shows the total resistance (RT), intrinsic membrane resistance (Rm), polarization concentration resistance (Rp) and fouling resistance (RF). Generally, Rm represents the smallest

Beverages 2017, 3, 44 11 of 15

Effect of transmembrane pressure on permeate flux of 400 gac oil 50 nm Water 50 nm 300

200 L/H/M2)

, J ( 100 FLUX Beverages 2017, 3, 44 0 11 of 15 012345 TMP (BAR) Table 6. Effect of TMP on coefficient of retention of total carotenoids content (TCC) in retentate. Figure 15. Effect of transmembrane pressure on permeate flux of gac oil (T = 30 °C; Membrane pore size Transmembrane= 100 nm). Pressure (bar) Coefficient of Retention of Carotenoids (%) 1 84 ± 2.6 a 4.2.3. Effect of Temperature2 on Permeate Flux and Coefficient of Retention 85 ± 2.5 ofa TCC in Retentate b Generally, an increase3 of temperature results in an increase90 of± permeate3.6 flux caused by a ± c decrease of viscosity of 4oil feed (Figure 16). This phenomenon can be 92 attributed3.5 to a reduction of feed 5 95 ± 3.2 d viscosity and to an increase of the diffusion coefficient of macromolecules. The effect of these two factors is toDifferent enhance letter mass superscripts transfer show and significant to increase differences permeate among flux the mean [1]. values The results in the same in column.Table 7 show that the change of temperature has an inversely proportional effect of coefficient of retention of TCC. The 4.2.3.temperature Effect of Temperaturemight also reduce on Permeate phospholipids Flux and micelle Coefficient size in of solution Retention because of TCC the in Retentatemolecules of phospholipidsGenerally, an did increase not aggregate of temperature together results at high in temperatures an increase of [23] permeate that lead flux to caused pass through by a decrease the of viscositymembrane of quickly oil feed and (Figure to minimize 16). This phenomenonthe fouling deposition. can be attributed Through to this a reduction experiment of feedresult, viscosity the maintenance of temperature at 40 °C is highly recommended for the gac oil filtration process because and to an increase of the diffusion coefficient of macromolecules. The effect of these two factors is to of its high flux permeates and relatively high effective retention of TCC. enhance mass transfer and to increase permeate flux [1]. The results in Table7 show that the change of temperature has anTable inversely 7. Effect proportional of temperature effect on retention of coefficient coefficient of of retention TCC in retentate. of TCC. The temperature might also reduce phospholipids micelle size in solution because the molecules of phospholipids did not aggregate together at highTemperature temperatures (°C) [23Retention] that lead Coefficient to pass throughof TCC the membrane quickly and 30 95 ± 3.8 a to minimize the fouling deposition. Through this experiment result, the maintenance of temperature 40 90 ± 3.6 b ◦ at 40 C is highly recommended for50 the gac oil filtration process88 ± 3.0 c because of its high flux permeates and relatively highDifferent effective letter superscripts retention show of TCC. significant differences among the men values in the same column.

40 Effect of temperature on permeate flux of gac oil 30C 40C 30

20 L/h/m2)

, J ( 10 Flux

0 0 20406080100120 Time (min) FigureFigure 16. 16.Effect Effect of of temperature temperature on on permeate permeate flux of gac oil oil (TMP (TMP = = 3 3bars; bars; Membrane Membrane pore pore size size = 100 = 100 nm). nm) .

4.3. Resistance Analysis Table 7. Effect of temperature on retention coefficient of TCC in retentate. Table 8 shows the total resistance (RT), intrinsic membrane resistance (Rm), polarization ◦ concentration resistanceTemperature (Rp () C)and fouling resistance Retention(RF). Generally, Coefficient Rm ofrepresents TCC the smallest a 30 95 ± 3.8 40 90 ± 3.6 b 50 88 ± 3.0 c Different letter superscripts show significant differences among the men values in the same column.

4.3. Resistance Analysis

Table8 shows the total resistance ( RT), intrinsic membrane resistance (Rm), polarization concentration resistance (Rp) and fouling resistance (RF). Generally, Rm represents the smallest portion of the RT. The total resistance is mainly contributed by RP, following by RF. During the ﬁltration process, small particles tend to be rejected by the membrane and they are deposited on the surface, contributing to a polarized layer formation that causes a high-polarized layer resistance. Beverages 2017, 3, 44 12 of 15

High RF caused by fouling due to blockage of pore, adsorption and gel layer particles. Compressibility of fouling cake need to be determined in further study.

Table 8. Resistance during ﬁltration process.

Cashew Apple Juice Dragon Fruit Juice Pomelo Juice Pineapple Juice Gac Oil TMP (bar) 1.5 3 1.5 2 3 Pore size (nm) 500 1000 500 500 50 Temperature ◦C 50 40 50 50 40 −1 a a a a a RT (m ) 346.54 ± 7.25 756.4 ± 13.55 425.4 ± 4.55 653.7 ± 9.72 434.8 ± 9.15 −1 b b b b b Rm (m ) 105.5 ± 4.52 125.6 ± 5.50 120.0 ± 4.25 143.6 ± 5.44 108.7 ± 4.66 −1 c b c c c RP (m ) 125.7 ± 6.25 256.9 ± 6.25 176.8 ± 6.30 224.5 ± 7.65 132.9 ± 5.87 −1 b c d d c RF (m ) 122.5 ± 5.00 352.6 ± 7.42 155.5 ± 6.32 202.5 ± 8.28 131.9 ± 6.25 Different letter superscripts show signiﬁcant differences among the men values in the same column.

4.4. Physiochemical Analysis The physiochemical properties of juice and gac oil (both of feeding and final product) are presented in Table9. At the operating conditions of the UF process (TMP, membrane pore size and temperature) obtained in total recycle mode, the batch mode was experimented to determine the physiochemical properties of final product. The results are presented in Table9 and compared with that of feeding juice and oil. The results show that the chemical composition of the product was not significantly modified by the process, and that the purified juice’s nutritional components were very close to those of the feeding juice. These results are in accordance with the results in other studies carried out with other different fruit juices [24,25]. A significant change in Lightness (L*) was also observed. The purified juice color became brighter than that of the feeding oil. The free fatty acids and phospholipids of gac oil are almost removed after the filtration process. TCC in retentate is 6 times higher than that of the feeding oil. Color of the concentrated oil is deeper than that of the feeding oil. This result is according with Fabrice [3] who indicated that the color of retentate was deeper orange caused by an increase of 3.3 times of carotenoids content after the melon juice filtration process. These results are also correlated to those of Gale [4], who showed that carotenoids remained in the fouling and the filter pads during the clarification of melon juice. Beverages 2017, 3, 44 13 of 15

Table 9. Physiochemical measurement of feeding vs permeate (fruit juice) and retentate (of gac oil).

Parameters Cashew Apple Juice Dragon Fruit Juice Pineapple Juice Pomelo Juice Gac Oil Feeding Permeate Feeding Permeate Feeding Permeate Feeding Permeate Feeding Retentate pH 3.9 ± 0.15 a 3.89 ± 0.1 a 4.5 ± 0.25 b 4.32 ± 0.2 c 3.8 ± 0.25 d 3.55 ± 0.1 e 2.8 ± 0.15 f 2.52 ± 0.12 g ND Viscosity (Pa.S) 0.012 ± 0.005 a 0.009 ± 0.0005 a 0.02 ± 0.005 b 0.015 ± 0.005 b 0.017 ± 0.005 c 0.012 ± 0.002 c 0.018 ± 0.005 d 0.015 ± 0.005 d 0.05 ± 0.002 e 0.25 ± 0.01 f Protein (g) 0.101 ± 0.005 a 0.098 ± 0.005 a 0.144 ± 0.005 b 0.120 ± 0.005 b 0.55 ± 0.03 c 0.22 ± 0.02 d 0.6 ± 0.05 e 0.455 ± 0.02 f ND Carbohydrate (g) 9.08 ± 0.52 a 8.78 ± 0.55 b 8.5 ± 0.72 c 7.55 ± 0.45 d 12.5 ± 0.45 e 10.55 ± 0.62 f 8.4 ± 0.44 g 7.22 ± 0.42 h ND TSC (%) 0.19 ± 0.01 a 0.1 ± 0.005 b 0.39 ± 0.01 c 0.22 ± 0.01 d 0.33 ± 0.01 e 0.20 ± 0.01 f 0.3 ± 0.01 g 0.25 ± 0.02 g 0.04 ± 0.005 h 0.20 ± 0.005 i TSS (◦Brix) 13.2 ± 0.75 a 11.5 ± 0.62 b 11.85 ± 0.65 c 10.52 ± 0.6 d 12.7 ± 0.5 e 10.64 ± 0.7 f 9.5 ± 0.52 g 8.22 ± 0.55 h 86.2 ± 5.25 i 98.56 ± 6.55 j Vitamin C (mg/100 g) 172 ± 9.55 a 155.7 ± 8.45 b 9.9 ± 0.55 c 8.22 ± 0.52 d 45.5 ± 3.66 e 40.55 ± 3.52 f 35.5 ± 2.45 g 32.7 ± 2.00 h ND Acid index (mg KOH/g) ND ND ND ND 2.25 ± 0.12 a 0.05 ± 0.002 b Phospholipids (%) ND ND ND ND 14. 3 ± 0.5 a 2.2 ± 0.15 b TCC (mg/ml) ND ND ND ND 7.55 ± 0.45 a 65.28 ± 4.22 b Color (L*) 47.35 ± 2.50 a 47.4 ± 2.00 a 52.65 ± 3.20 a 55.78 ± 2.50 b 67.69 ± 3.40 c 75.35 ± 4.25 d 72.3 ± 3.75 e 78.5 ± 2.55 f 45.2 ± 2.64 g 36.3 ± 2.25 h ND: not detected; Different letter superscripts show signiﬁcant differences among the men values in the same row for different fruit. Beverages 2017, 3, 44 14 of 15

5. Conclusions Cashew apple, dragon fruit, pomelo, and pineapple juices were clarified by the UF process at different operating conditions. Membrane pore size, TMP, and the temperature of processing have influence on the permeate flux and turbidity. Membrane pore size of 500 nm is highly recommended for juice clarification objectives. The reasonable pressure for UF processing of cashew apple, dragon fruit, pomelo, and pineapple juice is 1.5 bars, 3 bars, 1.5 bars, and 2 bars, respectively. The optimum temperature for UF processing is 50 ◦C, 40 ◦C, 50 ◦C, and 50 ◦C, respectively. The impact of these factors on other nutritional components should be further exanimated in order to control the quality of the final product. Carotenoids in gac oil can be concentrated by using the ultrafiltration membrane at the operating conditions. Membrane pore size of 50 nm is acceptable because of its high permeate flux and high coefficient of retention of TCC. TMP of 3 bars and temperature of 40 ◦C are highly recommended for gac oil filtration process because of its high flux permeates and relatively high effective retention of TCC. The total resistance is mainly contributed by RP, followed by RF. Compressibility of fouling cake needs to be determined in further study.

Acknowledgments: The researches were funded by Nong Lam University. Conﬂicts of Interest: The author declares no conﬂict of interest.

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