超滤在荔枝汁澄清中的应用

首次采用聚砜中空纤维膜对荔枝汁进行超滤澄清处理 ,超滤后果汁澄清透明 ,透光率达 99.5% ,无混浊现象 ,较好地保持了原汁的营养成分与风味 ,试验还探讨了超滤工艺参数对膜透过速率的影响     

Recovery of bioactive compounds in kiwifruit juice by ultrafiltration

Food quality is not only a function of nutritional values but also of the presence of bioactive compounds exerting a positive effects on human health.This research was undertaken to study the influence of the ultrafiltration (UF) on the composition of some bioactive compounds of the kiwifruit juice in order to develop a natural product which can be used to fortify foods and beverages. At the same time the effect of transmembrane pressure (TMP) and temperature on the permeate flux was also investigated in order to identify the optimal operating conditions for the processing of the juice. An optimal TMP value occurred at 0.6–0.65 bar in different conditions of cross flow velocities. Steady-state permeate fluxes increased linearly with temperature in the range 20–30 °C.The kiwifruit juice was clarified in optimal operating conditions, according to the batch concentration mode, up to a final volume reduction factor (VRF) of 2.76.The analyses of flux decay according to fouling models reported in the literature revealed that the formation of a cake layer covering the entire surface of the membrane is the main cause of the membrane fouling.Most bioactive compounds of the depectinised kiwifruit juice were recovered in the clarified fraction of the UF process. The rejection of the UF membrane towards total phenolics was 13.5%. The recovery of glutamic, folic, ascorbic and citric acids, in the clarified juice, with respect to the initial feed, was dependent on the final VRF of the UF process: an increase of the VRF determines an increase of these compounds in the clarified juice. The rejections of the UF membrane towards these compounds were in the range 0–4.3%.

Industrial relevance

Among different substances contained in the kiwifruit a primary role, in the safeguard of the human health, is carried out by some bioactive compounds such as ascorbic, folic, citric, glutamic acids and polyphenols.This research was undertaken to study the influence of ultrafiltration on the composition of these compounds in order to develop a natural product which can be used to fortify foods and beverages.     

Deacidification of passion fruit juice by ultrafiltration and ion-exchange processes

Deacidification of passion fruit juice by a combination of ultrafiltration (UF) and ion-exchange was studied. Prefiltering the juice by UF facilitated the ion-exchange process. At a feed rate of 700 ml h⁻¹, weakly basic resins removed nearly 95, 80 and 50% titrat-able acids from five, seven and twelve bed volumes of UF permeate, respectively, and did not cause significant sugar losses. UF retentate can be added back to the deacidified UF permeate to restore the suspended solids and some flavour components.     

陶瓷膜超滤净化石灰法制糖清汁

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

Effect of previous enzymatic recirculation treatment through a tubular ceramic membrane on ultrafiltration of model solution and apple juice

The process of ultrafiltration of a model solution and 12% soluble solids apple juice containing pectins through tubular membranes of 100 and 300 kDa (1 and 3 channels) was studied. Furthermore, in order to obtain a higher permeate flow, the fluids were previously treated with pectinolytic enzymes recirculating through a tubular membrane at different concentrations and treatment times. The permeate flow was analyzed with respect to time and the influence of enzymatic treatment on different parameters: viscosity, density, absorbance at 420 nm, reducing sugars, °Brix, color and pH. Depectinization increased the permeate flow for the model solution and apple juice with 67.52% and 53.11% when the pectinolytic enzyme preparation re-circulated across the tubular membrane. Using the lowest concentration of enzyme treatment and the longest recirculation treatment, an increase in permeate flow was obtained leading to a more favourable clarification process and economic benefits.     

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。     

EFFECTS OF CO-IMMOBILIZATION OF PECTINASE AND AMYLASE ON ULTRAFILTRATION OF APPLE JUICE SIMULATE

In view of its possible application in apple juice clarification, the potential of co‐immobilized pectinase/amylase by physical adsorption on a polysulfone ultrafiltration hollow fiber was examined. Solutions containing different concentrations of pectin and starch were used. The effect of various operational parameters on the production of reducing compounds, mainly galacturonic acid and maltose, was investigated. Results indicated that relative permeate flux, during ultrafiltration of starch‐pectin solutions, was up to 35% higher when commercial pectinase and amylase were co‐immobilized on a hollow fiber membrane. Although the concentration of reaction products increased up to 50% with the pectin concentration, the same was not verified when the starch content changed from 3.85 to 5.00 mg/mL. However, the reference permeate flux was improved when starch was added to substrate, independently of its concentration. Considering the size of an average starch granule, this increase in permeate flux was attributed to the removal of pectin gel by dragging. Permeate fluxes were comparable for both batch and permeate recycling operations.     

膜分离技术及其在果汁加工中的应用

介绍了应用于果汁加工中的膜分离过程(微滤、超滤、纳滤、反渗透、电渗析、膜蒸馏)及其分离性能。由渗透通量和截留率表征,在果汁加工中,膜分离技术可用于果汁的澄清、浓缩、脱气、脱苦、脱酸、脱色等。     

Effects of pretreatment and various operating parameters on permeate flux and quality during ultrafiltration of apple juice

The central composite design with a quadratic model was used to investigate the effect of temperature (20–40 °C) and transmembrane pressure (TMP) (100–300 kPa) as well as pretreatment with gelatin and bentonite (0:0–300:1500 mg L^?1) on permeate flux and fouling resistance during ultrafiltration of apple juice. The changes in some physicochemical properties were also investigated. Pretreatment of apple juice with gelatin and bentonite and an increase in the temperature and TMP significantly improved the permeate flux. In general, physicochemical properties of apple juice other than polyphenolics were not affected by the applied parameters. Using 150 mg L^?1 of gelatin and 750 mg L^?1 of bentonite for fining significantly reduced the total phenolic content and so did the fouling resistance. Fouling resistance also decreased with increasing temperature, and increasing pressure increased the fouling resistance.     

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.     

Short communication: utilization of sheep's milk cheese whey in the manufacture of an alkylphenol flavor concentrate

The recovery of species-related conjugated sheep-like flavored alkylphenols from Manchego-type cheese whey by ultrafiltration was investigated. Concentrations of conjugated alkylphenols were similar in the various fractions of whey permeate collected during ultrafiltration, and this was interpreted as a reflection of their high water solubility. About 49 and 62% of conjugated 3- and 4-ethylphenols and p- and m-cresols in sheep's milk cheese whey, respectively, were recovered in the permeate after ultrafiltration with a volume concentration factor of 5.4. Cheese whey retentate correspondingly contained 38 and 28% of conjugated 3- and 4-ethylphenols and p- and m-cresols from the original whey, respectively. Permeate fractions from sheep's milk cheese whey were combined, concentrated by vacuum evaporation, and lactose was partially removed by crystallization and filtration to obtain an aqueous sheep-like flavor precursor concentrate.     

A Process to Produce Light Colored Protein Isolate from Defatted Glandless Cottonseed Flour

Light colored protein isolates could be produced from aqueous protein extract (at pH 9.0) of defatted cottonseed flour by filtering through an ultrafiltration membrane with 100,000 MWCO (molecular weight cut off) pore size and then spray-drying the retentate. The yield of this protein fraction was approximately 68% of the extracted solid. About 15% of the extracted solid was recovered with the low molecular fraction (50,000 daltons) when the permeate of 100,000 MWCO was applied to 50,000 MWCO membrane. Most of the color-causing pigments were associated with the low molecular fraction.     

EFFECTS OF PECTINASE IMMOBILIZATION DURING HOLLOW FIBER ULTRAFILTRATION OF APPLE JUICE

The immobilization of commercial pectinases by physical adsorption on hollow fiber ultrafiltration (HFUF) membranes was studied in view of its possible application in fruit juice clarification. The optimal pH during immobilization and washing was investigated, as well as the effects of enzyme and pectin concentrations and retentate flow on the operation. Results indicated that permeate flux was not initially increased when pectin solution or apple juice was ultrafiltred through pectinase immobilized on HFUF membranes. However, enzyme immobilization greatly extended the membrane operation, by keeping permeate flux constant during prolonged periods at a reasonable yield.     

Effect of membrane property and operating conditions on phytochemical properties and permeate flux during clarification of pineapple juice

The effects of membrane property on the permeate flux, membrane fouling and quality of clarified pineapple juice were studied. Both microfiltration (membrane pore size of 0.1 and 0.2 μm) and ultrafiltration (membrane molecular weight cut-off (MWCO) of 30 and 100 kDa) membranes were employed. Membrane filtration did not have significant effects on the pH, reducing sugar and acidity of clarified juice whereas the suspended solids and microorganism were completely removed. The 0.2 μm membrane gave the highest permeate flux, total vitamin C content, total phenolic content and antioxidant capacity as well as the highest value of irreversible fouling. Based on these results, the membrane with pore size of 0.2 μm was considered to be the most suitable membrane for the clarification of pineapple juice. The optimum operating conditions for the clarification pineapple juice by membrane filtration was a cross-flow velocity of 3.4 ms⁻¹ and transmembrane pressure (TMP) of 0.7 bar. An average flux of about 37 lm⁻² h⁻¹ was obtained during the microfiltration of pineapple juice under the optimum conditions using batch concentration mode.     

用中空纤维超滤膜法澄清橙汁

对中空纤维超滤膜法澄清橙汁(Citrus sinensis)进行了研究。试验着重研究了操作压力、温度、物料浓度和进料流速对膜透过速率的影响,并测定了超滤(?)中的营养成分的保存率。还探讨了超滤作为膜蒸馏浓缩预处理的可能性。结果表明,超滤法澄清橙汁是可行的．对果汁营养成分及风味无显著影响。由于超滤除去了果胶等固形物,因此能提高膜蒸馏过程的蒸馏通量。     

Effect of Ultrafiltration on Anthocyanin and Flavonol Content of Black Currant Juice (Ribes nigrum L.)

This paper evaluates the efficiency of ultrafiltration and the effects of processing on the total anthocyanin and flavonol contents of black currant juice at chosen operational conditions. Ultrafiltration of black currant juices was carried out using Biomax 100?kDa polyethersulfone membrane. Ultrafiltration was used to process the juice prior concentration by reverse osmosis; with the aim to enhance the efficiency of the concentration process in terms of permeate flux. To avoid the fouling of the membrane, the juices were depectinized with Panzym Super E liquid enzyme preparation. The ultrafiltration was carried out at a transmembrane pressure of 2?bars and the operating temperature of 25?°C. The effect of processing on the valuable anthocyanin and flavonol content of the juices was evaluated based on the results of high-performance liquid chromatography analyses. The article includes detailed analyses of anthocyanin and flavonol compounds of the enzyme treated and ultrafiltered juice as compared with the original juice. The results indicate that, due to the enzymatic treatment, the valuable compound content of the juice increases. However, the ultrafiltration process resulted in a significant loss of a valuable content; 54% of total flavonol and 50% of total anthocyanins maintained in ultrafiltered juice when compared to the feed samples.     

The quality of orange juice processed by coupling crossflow microfiltration and osmotic evaporation

Crossflow microfiltration (CFM) and osmotic evaporation (OE) were implemented on a semi‐industrial pilot scale to obtain clarified orange juice concentrates at 450 and 620 g kg^?1 of total soluble solids. The characteristics of the juice were then assessed and compared with fresh juice and commercial concentrates. With CFM, most aroma compounds and vitamin C remained in the permeate while the more apolar compounds such as terpenic hydrocarbons and carotenoids were strongly retained by the membrane. With OE, significant losses of vitamin C and aroma compounds occurred at first, with losses progressively decreasing during treatment. Pre‐conditioning the membrane and cold regeneration of the brine reduced losses drastically, with the aroma composition tending towards that of the initial juice. The quality of pulp, a blend of the CFM retentate and OE concentrate, was high and much closer to that of the initial fresh juice than to the commercial thermal concentrate.     

不同预处理方式对柠檬果汁超滤澄清效果和膜污染情况的影响

利用超声辅助果胶酶法和超滤技术相结合对柠檬果汁进行澄清。以柠檬汁的透光率、果胶含量为指标,讨论不同预处理方式对柠檬果汁超滤澄清效果和膜污染情况的影响。结果表明,采用切割分子量为50 kDa的聚丙烯腈(PAN)超滤膜澄清果汁,不同预处理方式对超滤膜的稳定通量大小的影响规律是酶+超声处理>酶处理>未经酶+超声处理,其稳定通量分别为30、33.5和13 L·m-2·h-1左右。较优的操作压力可确定为0.1 MPa,此时柠檬汁的果胶含量为0.5%,透光率约99.6%,处理效果较好。超声辅助果胶酶法澄清果汁,有利于提高果汁的透光率,并且在后续膜处理过程中,对于提高超滤膜的通量和缓解膜污染都有显著的效果。     

浓缩苹果清汁加工过程中色值稳定性研究

分别以富士及秦冠苹果为原料,研究了果胶酶PA和PP联合使用对两种浓缩苹果清汁加工过程中色值稳定性的影响,并对加工中超滤通量、树脂运行时间的影响进行了分析。实验结果表明:与单一使用PA果胶酶相比,复合果胶酶可以有效提高超滤、灌装工艺后苹果清汁的色值。确定了复合果胶酶的适宜添加量为PA为25 mL/t,PP为10 mL/t,适宜酶解时间为60 min。此工艺下,超滤清汁色值(T₄₄₀)提高2.2%,灌装前后产品色值变化在3%以下,4 ℃下贮藏的日褐变量在0.05%以下;且每周期超滤平均通量及树脂有效运行时间均提高10%以上。PA和PP的联合使用是解决浓缩苹果清汁加工过程中色值下降且提高其贮藏稳定性的有效技术手段。     

Recovery and concentration of phenolic compounds in blood orange juice by membrane operations

Cross-flow ultrafiltration (UF) and osmotic distillation (OD) were implemented on laboratory scale to obtain formulations of interest for food and/or pharmaceutical industry starting from the blood orange juice produced in the Calabria region. The freshly squeezed juice, after a depectinization step, was submitted to an UF process in order to recover natural antioxidants, such as hydroxycinnamic acids, hydroxybenzoic acids, flavanones, flavan-3-ols, and anthocyanins. The UF permeate, with an initial total soluble solids (TSS) content of 10.5°Brix, was concentrated by OD up to a final concentration of 61.4°Brix.