柠檬果汁超声辅助果胶酶澄清工艺研究

利用超声辅助果胶酶法对柠檬果汁进行澄清。以柠檬汁的透光率、果胶含量为考察指标,在单因素实验的基础上,通过正交试验对柠檬汁的澄清工艺参数进行了优化。结果表明,柠檬果汁澄清的最佳工艺:果胶酶的添加量0.05%,超声功率90W,温度40℃,超声时间10min。此时所得到的柠檬汁中果胶含量为2.2%,透光率为76.9%。与酶处理相比,超声波辅助果胶酶可显著降低果汁中的果胶含量,柠檬汁的透光率略有降低。     

红柠檬果汁澄清工艺的优化

选用红柠檬作为研究对象,以透光率为指标来研究果胶酶、复合酶、壳聚糖、膨润土和硅藻土这5种澄清剂对红柠檬汁的澄清效果,并探讨其中澄清效果较好的澄清剂对澄清后果汁品质的影响。通过单因素试验和Box-Behnken试验设计对红柠檬汁澄清工艺进行优化。结果表明,膨润土和硅藻土对红柠檬汁几乎没有澄清作用,果胶酶、复合酶和壳聚糖澄清效果都比较好。综合经济、方便和澄清后红柠檬汁品质3个方面考虑,最后选择果胶酶作为红柠檬汁的澄清剂。利用响应面优化试验得到了澄清型红柠檬汁的最优工艺,其条件为果胶酶用量0.22 g/100mL、处理温度50.3℃、pH 4.3和时间62 min,在此条件下,红柠檬汁透光率为93.8%。     

山楂果汁澄清工艺研究

利用单因素实验方法,研究了壳聚糖、果胶酶对山楂果汁澄清效果的影响。通过均匀实验设计,得到壳聚糖、果胶酶复合澄清的回归模型,并确定了最佳工艺条件:壳聚糖添加量0.18g/L、果胶酶添加量1.36U/mL,在50℃下处理1.7h。比较不同超滤膜对山楂浸提汁的超滤结果,PES-30膜的超滤透过液透光率超过93%,而且色度下降较小,保持了山楂特有的鲜艳红色。     

不同澄清方式对石榴果汁澄清效果的比较

研究以果汁透光率为指标,比较膨润土、果胶酶、壳聚糖三种澄清方式对石榴果汁澄清效果,结果表明,果胶酶澄清效果最好,壳聚糖次之,膨润土最差,果胶酶澄清后的果汁稳定性最好,壳聚糖和膨润土澄清后的果汁稳定性较差。通过比较三种澄清方式对石榴果汁中主要物质含量的影响发现,果胶酶对果汁中的蛋白质、果胶及酚类物质去除能力最高,壳聚糖次之,膨润土最差。通过比较三种澄清方式对果汁色差的影响发现,果胶酶处理后的果汁L值最大,壳聚糖次之,膨润土最小。通过正交试验优化石榴果汁澄清工艺,结果表明,当果胶酶用量为0.08%,酶解时间为1.5 h,酶解温度为50℃时,果汁澄清效果最好。     

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。     

冷冻与酶解相结合澄清芦柑果汁的工艺研究及质量评价

研究冷冻法与果胶酶酶解法相结合对芦柑果汁的澄清作用,同时探讨此澄清方式对果汁品质的影响。实验以新鲜芦柑果肉为原料,先进行冷冻预处理,自然解冻榨汁、离心后再用果胶酶对果汁进行澄清。结果表明,芦柑果肉冷冻预处理的最佳温度为—20℃、时间为60 min,得到的果汁透光率和出汁率分别为80.57%、82.86%;果胶酶酶解的最优工艺参数为:酶添加量0.05 g/L、酶解温度45℃、酶解时间0.5 h,酶解处理后果汁的透光率和出汁率分别达到94.16%、90.38%;经冷冻与酶解相结合处理后汁液的Vc含量由26.77 mg/100 g降为25.48 mg/100 g,可溶性固形物及总糖下降较多,分别由9.6%、10.2 g/100 mL降为8.4%、7.8 g/100 mL,果胶和可溶性蛋白质几乎被完全分解;澄清汁储存稳定性良好。因此,该复合澄清工艺合理可行,可为芦柑果汁的深加工提供理论依据。     

枸杞山楂复合果汁的澄清工艺条件研究

研究了使用果胶酶澄清枸杞山楂复合果汁的工艺条件,结果显示,在果胶酶用量5g/L、果汁pH3.2、酶解温度50℃、酶解时间2.5h的工艺条件下澄清的枸杞山楂复合果汁,透光率可达94.8%。果胶酶能有效地去除枸杞山楂复合果汁中的果胶物质。     

超滤和果胶酶处理对澄清型红葡萄汁质量的影响

采用国产超滤膜和果胶酶生产葡萄汁，试验结果表明，利用０．０２％￣０．０４％的果胶酶处理，超滤前用微波加热到７０℃进行预澄清处理，利用７０ｋｕ的超滤膜进行超滤，可以制得透光率在９０％以上的澄清型红葡萄汁。     

超滤法处理桉木CTMP制浆废液的初步研究

采用截留相对分子质量为1000～30000的4种超滤膜对桉木CTMP制浆废液(包括化学预处理段及磨浆段)进行了超滤处理,找出了最佳处理效果的膜孔径,并用该孔径的膜对4种不同工艺的废液进行超滤处理,使废液的污染负荷大幅度降低,滤过液的生物可处理性明显提高。超滤浓缩液的固形物含量达到可蒸发、浓缩及烧却的要求。超滤膜清洗后,膜通量可恢复99%。     

中空纤维超滤膜澄清蓝莓果汁工艺研究

采用中空纤维膜超滤技术研究蓝莓果汁澄清工艺条件。在单因素试验的基础上,采用Box-Benhnken响应面分析对影响蓝莓果汁超滤的关键因素(操作压力、温度、料液流速)进行优化,拟合得到二次多项式回归方程的预测模型,并确定最优条件为:压力0.08MPa、料液流速1.3L/min、温度35℃。超滤处理后的蓝莓果汁透光率为97.8%,膜通量为36.59mL/(m2·min),处理后蓝莓果汁的澄清度明显提高,但对糖、酸等含量变化无明显影响。     

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.     

ALTERNATIVE PRETREATMENT METHODS TO ENZYMATIC TREATMENT FOR CLARIFICATION OF MOSAMBI JUICE USING ULTRAFILTRATION

A series of pretreatment methods to mosambi juice were undertaken and results were compared to pectinase treatment for clarification of the treated juice using ultrafiltration. The pretreatment methods attempted were centrifugation, centrifugation followed by addition of gelatin, centrifugation followed by addition of bentonite, centrifugation followed by fining using both bentonite and gelatin and enzymatic treatment, using pectinase as the enzyme. A systematic study was undertaken to select the operating centrifugation speed and time. The permeate flux and quality of the permeate were comparable to the enzyme‐treated juice.     

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.     

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.     

果胶酶澄清枸杞汁最佳工艺条件研究

选用果胶酶对枸杞汁进行澄清,在最适pH和不调pH条件下、以及最适温度和常温作用下比较了果胶酶对枸杞汁澄清效率及可溶性固形物含量的影响效果。结果表明:果胶酶的澄清效果受温度的影响较大,调节pH值对澄清度的影响则表现不明显。且酶处理不增加枸杞汁的可溶性固形物含量。正交试验证明:最佳澄清工艺条件为:pH4.0,酶解温度55℃,作用时间6h,酶剂量40mg/kg。     

一株低产甲醇的果胶酶菌种选育及产酶工艺优化

红枣加工过程中,由于红枣较普通水果含果胶物质高,用普通果胶酶进行酶解后枣汁中的甲醇含量过高,对人体健康有害。实验筛选出产甲醇低的果胶酶产生菌黑曲霉A11,其产甲醇含量比市售果胶酶低3.63%,并通过响应面试验得到A11发酵产酶的最佳工艺条件为发酵液中果胶的添加量2.99%,pH值6.00,温度36℃,接种量为0.5%,发酵时间48h,酶活力7.72U/mL。     

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.     

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.     

壳聚糖固定化果胶酶在枇杷果汁澄清中的应用

以戊二醛为交联剂,壳聚糖为载体固定化果胶酶,对其在枇杷果汁澄清中的应用进行研究。结果表明:固定化果胶酶澄清枇杷果汁的工艺条件为:固定化酶浓度为50 g/L(果汁),果汁pH值为3.8,果汁体积分数为60%,酶解温度和时问分别是50℃和2 h。固定化果胶酶比游离酶处理枇杷果汁的澄清效果好,固定化酶酶解后果汁的糖度没有变化,酸度略有下降,渣汁分层速度加快,果汁色泽由褐色转变为黄色,冷热稳定性也提高了。