Effect of membrane clarification on the physicochemical properties of pomegranate juice

Pomegranate juice (PJ) has a turbid appearance which can be clarified by membrane processing. The effect of membrane processing with hydrophilic polyvinylidene fluoride with pore sizes of 0.22 and 0.45 μm and mixed cellulose esters (MCE) with pore sizes of 0.22, 0.1, and 0.025 μm on physicochemical properties of PJ were evaluated. Turbidity, suspended solids, acidity, total soluble solids, total phenolic content and antioxidant activity decreased after passing through the membrane at the same rate for all membranes tested. Total soluble solids content (with mean rejection factor = 20.8%) and antioxidant activity (Efficient concentration 50 was duplicated) had the smallest and the greatest reduction in all membranes, respectively. Also, five important anthocyanins identified by LC/MS decreased after PJ clarification at the same rate for all membranes. Pelargonidin 3‐glucoside had minimum reduction (mean rejection = 7.7%). Ellagic acid also decreased for all membranes. However, MCE 0.025 μm membrane resulted in a greater decrease than did the other membranes (mean rejection = 24.3%).     

Modelling the membrane clarification of pomegranate juice with computational fluid dynamics

The fluid behaviour of pomegranate juice—specifically, its velocity and pressure distribution form—can affect yield during the clarification process. This study used computational fluid dynamics (CFD) to predict velocity and pressure patterns in the membrane module during the clarification of pomegranate juice. Module geometry was plotted using GAMBIT software, and the problem was solved using FLUENT 6.2. The results showed that declines in velocity in the feed channel before fouling creation were greater than after fouling creation. Also, maximum value for velocity at the start of the process was lower than at the final stages. Moreover, the feed entrance and retentate exit must have a parallel pattern with the membrane surface to avoid membrane damage from high pressure at the feed entrance. Establishing this parallel pattern allows all surfaces of the membrane to be used for effective clarification.     

Study on the development of pomegranate juice processing technology: clarification of pomegranate juice

The effects of clarification agents and methods on pomegranate juice quality were studied. Fruits were pressed as whole, and extracted juice was clarified with gelatin, polyvinylypolypyrrolidone (PVPP) and natural sedimentation. In order to determine the effects of these clarifying techniques on product quality, pH, total phenolic substances (TPS), anthocyanin, turbidity, and total colour density tests were applied to each sample. In clarification, the main purpose was to reduce the amount of phenolic substances. Phenolic substances were controlled in each clarification method. The most effective method was the application of 1 g/L gelatine for clarification. Sensory evaluation also applied for clarified juices and gelatin application was selected by panelists to be superior.     

酶法澄清石榴果汁的研究

探讨了果胶酶添加量、温度、时间、果汁稀释倍数对石榴汁澄清的影响,在单一因素基础上,果胶酶用量1830￣2550U/mL、酶促反应温度为40￣55℃、澄清时间1.5￣2.5h、稀释倍数0￣5,透光率达59.1%。进行正交实验确定最佳条件,结果表明:石榴果汁中果胶酶用量1830U/mL、澄清时间2h、温度50℃、稀释倍数0,可达到最好的澄清效果。     

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.     

陶瓷膜在苹果汁澄清中的应用研究

采用国内研制的陶瓷膜进行苹果汁的澄清实验研究.实验结果表明氧化锆陶瓷膜可有效地澄清苹果汁,澄清果汁的各项指标达到出口果汁指标;并与国外陶瓷膜设备作同期运行对比,其澄清效果、通量的稳定性等方面均达到或超过国外陶瓷膜的处理结果.同时实验还对湍流促进器强化无机膜微滤过程以及膜清洗方法进行了考察,确定了无机陶瓷膜膜过滤苹果汁合适的操作参数.     

Combined use of hydrocolloids in pomegranate juice and their effects on clarification and copigmentation

Pomegranate juices (PJs) were clarified using hydrocolloids [albumin (A), casein (C), chitosan (CH) and xanthan gum (XG)] and in combination with each other. The lowest turbidity was observed in PJs clarified with ‘CH+XG’ and ‘A+C+CH’. Unlike ‘CH+XG’, effects of albumin and its combinations on clarity were mainly related with the contents of ellagic acid (r = −0.861), α-punicalagin (r = −0.761), rutin (r = −0.734), β-punicalagin (r = −0.730) and total punicalagin (r = −0.713). ‘CH+XG’ caused the highest phenolic (602 mg L⁻¹) and anthocyanin (449 mg L⁻¹) contents, and the second highest A_max (0.811 ABS), resulting from copigmentation of delphinidin-3-glucoside and delphinidin-3,5-diglucoside with CH. Since A showed moderate copigmentation effect, A had lower hyperchromic effect than CH. Moreover, C reduced A_max, anthocyanin content and colour density when combined with other hydrocolloids. As a result, ‘CH+XG’ would be the best combination to obtain high clarity, maintain phenolics and anthocyanins and provide high copigmentation effect in PJ.     

Changes in blocking mechanisms during membrane processing of pomegranate juice

The effect of pressure, velocity, pretreatment, membrane type and pore size on fouling mechanisms were evaluated. Pomegranate juice was treated with polyvinylidene fluoride (PVDF) 0.22 μm and mixed cellulose ester (MCE) 0.1 μm at different pressures. Cake formation which was the dominant mechanism was formed in the first stages of process and, as the filtration proceeded, intermediate, standard, and complete blocking, respectively occurred at higher pressure (5 kPa). At lower pressure (0.5 kPa) the last mechanism did not occur. Results showed that cake formation was the only mechanism in MCE 0.22 μm, however, others occurred with MCE 0.1 μm and PVDF 0.22 μm. Using MCE 0.22 μm prior to MCE 0.025 μm can reduce the role of cake formation in pore blocking. Evaluation of the impact of velocity showed that at the higher velocity (0.53 m s⁻¹) the complete blocking occurred faster than at the lower velocity (0.09 m s⁻¹).     

Application of sepiolite in clarification of pomegranate juice: changes on quality characteristics during process

In this study, for the first time, the function of acid‐activated sepiolite clay was evaluated for clarification of pomegranate juice. The optimum conditions of clarification process were achieved using response surface methodology based on juice turbidity as a response. After that, under optimal condition, efficiency of sepiolite, bentonite and combination of these fining agents with gelatin and kieselgel was compared for clarifying pomegranate juice. The results showed that the best conditions for juice clarification were 0.05% (w/v) clay concentration, temperature of 50 °C and time of 2 h. The results revealed that treatments of bentonite–gelatin–kieselgel and sepiolite–gelatin–kieselgel were the most active fining agents that their use led to a reduction of 99.7% in turbidity of pomegranate juice. Kinetic study for different features was performed, and the results indicated that rate of changes in turbidity, viscosity, total phenolic contents and colour with time followed first‐, first‐, zero‐ and zero‐order kinetic models, respectively.     

石榴汁膜除菌工艺研究

以新疆和田酸石榴为原料制作石榴汁,用不同孔径的陶瓷膜对石榴汁进行除菌过滤,对比不同孔径膜的膜通量、除菌效率、成分截留率等参数,确定适于石榴汁膜除菌的膜孔径;并研究了石榴汁陶瓷膜除菌最佳工艺。结果表明,用于石榴汁除菌陶瓷膜的孔径为0.22μm;最佳工艺参数为压力0.20MPa、温度20℃。通过陶瓷膜过滤,可以有效去除石榴汁中的悬浮物和有害微生物,同时保留了其中的营养成分,避免了加热杀菌过程中的褐变、营养成分损失等问题。     

Evaluation of the fouling phenomenon in the membrane clarification of black mulberry juice

Mixed cellulose ester (MCE) flat membranes were used to clarify black mulberry juice, the yield of which was limited by fouling. The effects of membrane pore size (0.025, 0.1 and 0.22 μm), transmembrane pressure (0.5, 1, 1.5 and 200 kPa), and cross‐flow velocity (0.1, 0.2, 0.3 and 0.4 m s^?1) on membrane fouling were evaluated; the results showed that fouling increased with increased pore size and pressure, and decreased with increased velocity. Analysis of different resistances showed that both reversible and irreversible fouling resistances have an important role in fouling‐resistance changes. There is no cake resistance in all processes. Microstructure analysis of membrane using scanning electron microscopy confirmed the theory that intermediate blocking was the dominant fouling mechanism in MCE 0.025 μm, and standard blocking was the dominant mechanism in MCE 0.1 and 0.22 μm.     

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。     

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.     

Study of different fouling mechanisms during membrane clarification of red plum juice

In this study, the flux decline mechanisms were identified during membrane clarification of red plum juice at several processing parameters, including pore size, membrane type, transmembrane pressure, temperature and velocity. The results were used to investigate the effect of changes in operating conditions on the intensity of membrane fouling. Also, scanning electron microscopy (SEM) was used for analysing fouling‐layer morphology. These results showed that the main mechanism responsible for membrane fouling was cake formation (over 95% fitness) occurring in the first stage of the process. Intermediate, standard and complete blockings were formed during most of the runs as filtration proceeded. The results also indicated that increasing the temperature from 30 to 40 °C was the most effective factor in decreasing cake‐layer fouling, reducing it by about 66.7%. Furthermore, an increase in processing velocity of up to 0.5 m s^?1 had the greatest effect on intermediate blocking, reducing it by about 86.1%. Also, increasing pressure up to 2.9 bar completely eliminated standard blocking and complete blocking. Finally, microstructure analysis of membrane using SEM confirmed that cake formation had the greatest impact on membrane fouling.     

酿酒葡萄汁的静置澄清

法国葡萄酒历史悠久,闻名遐尔,其酿造工艺、技术非常精湛,对每个工艺过程研究都很详细而深入。在如何提高葡萄酒质量方面他们有着独到的见解。他们将影响白葡萄酒质量的因素及其所占比重划分为5个方面:压榨40%澄清20%温度15%酵母10%贮存15%由此可见,看似简单的“澄清”工艺占有不小的比重,是提高葡萄酒质量不可忽视的环节。下面将法国葡萄名种——霞多丽葡萄汁的静置澄清工艺作以介绍,谨供参考借鉴。1 葡萄汁澄清原理加SO2处理后的葡萄汁在澄清罐中的主要转化形式:(1)果胶的降解果胶经葡萄本身含有的果胶酶产生果胶降解物(解聚作用)注:这…     

Mathematical modelling of mass transfer in the concentration polarisation layer of flat‐sheet membranes during clarification of pomegranate juice

Evaluation of membrane clarification of pomegranate juice showed that a cake layer is created at the beginning of the process. This evaluation was used as the basis for modelling the solute concentration in the concentration polarisation layer to control the fouling of the membrane. The model of changes in concentration as a function of time and distance (in its dimensionless form) was solved numerically using the Forward‐Time/Central‐Space (FTCS) method. Programming was performed using MATLAB software, and the predicted concentration on the membrane surface was compared with experimental data; the prediction fit well with the experimental data. The model showed that the solute concentration increased as distance to the membrane surface decreased, time increased, transmembrane pressure increased and velocity decreased. Also, the model matched the experimental data in that it showed the cake layer to be created in the early stages of the membrane clarification process.     

保健型石榴清汁饮料的研制

水果中的佳品石榴,种植广泛,营养丰富,石榴的保健功能显著。经榨汁、澄清处理后,加入双歧因子(异麦芽低聚糖)、蜂蜜等经科学调配后,酸甜适口,清澈透明无沉淀,是一种具有开发潜力的新型保健饮料。