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 fining treatment and storage temperature on the quality of clarified banana juice

The clarified banana juice was subjected to different treatment namely bentonite, combination of gelatin and bentonite and control and stored at 4, 25 and 37 °C for 24 weeks. The effects of fining treatment, storage temperature and storage time on turbidity, total polyphenol, browning index, microbiological, and sensory quality of clarified banana juice were evaluated during storage. Fining treatment, storage temperature and storage time had a significant (p<0.001) effect on turbidity, total polyphenol and browning index of clarified banana juice. Turbidity and browning index of juice were reduced by fining treatment with bentonite and a combination of gelatin and bentonite but increased with storage temperature and storage time. A significant decrease in total polyphenol content and increase in turbidity and browning index were detected for all juice samples during storage. However, it was noted that changes were significantly greater in control juice stored at higher temperature than in juice stored at 4 or 25 °C for up to 6 months. Sensory evaluation revealed that juices treated with bentonite or a combination of gelatin and bentonite and stored at 4, 25 or 37 °C were acceptable for up to six months, whereas untreated juice stored at 37 °C was only acceptable for up to 16 weeks.     

Effects of Chitosan Treatments on the Clarity and Color of Apple Juice

Acid-soluble and water-soluble chitosans as fining agents for apple juice were compared to conventional silica sol/gelatin/bentonite treatment. Both chitosans proved equally effective in reducing juice turbidity as compared to control treatments and slightly lighter juices resulted from chitosan treatments. Use of the one step chitosan treatment appeares an attractive alternative to conventional fining processes.     

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.     

红树莓果汁澄清剂的选择及澄清工艺的优化

以红树莓果汁为实验材料,选用壳聚糖、明胶、PVPP、果胶酶、皂土五种澄清剂对红树莓果汁进行单因素试验,以红树莓果汁的透光率为指标对比五种澄清剂的澄清效果;从中选择澄清效果较好的澄清剂,再通过正交优化试验筛选出红树莓果汁最佳的澄清工艺条件。结果表明,在单因素试验中,5种澄清剂对红树莓果汁都具有一定程度的澄清和脱色作用,壳聚糖和明胶的对红树莓果汁的澄清效果较好,PVPP和皂土次之,果胶酶的澄清效果不佳;通过正交优化试验和验证试验得出壳聚糖在质量浓度1.8 g/L、澄清温度40℃、澄清时间36 h的条件下澄清效果最佳,可以得到清澈透明且均一稳定,透光率达96.7%的红树莓果汁。该工艺可为红树莓资源的综合开发利用提供参考。     

澄清剂和温度对赤霞珠葡萄酒澄清效果的影响

为研究不同澄清剂和澄清温度对赤霞珠葡萄酒的澄清效果,本研究首先采用不同浓度梯度的皂土、明胶和海藻酸钠对2017年自酿赤霞珠葡萄酒进行澄清处理,以浊度、透光率、总酚含量和色度为评价指标,分别确定三种澄清剂的最佳使用量,筛选出两种澄清效果较好的澄清剂。此外,研究了筛选出的两种单一澄清剂(明胶:皂土)以1:1的配比组成的复合澄清剂,在不同温度(10、4、0和-4 ℃)下对赤霞珠葡萄酒澄清效果的影响,进而确定了赤霞珠葡萄酒澄清处理的最适温度。结果表明:单一澄清剂处理效果最佳的为明胶0.5 g/L,其次是皂土0.5 g/L、海藻酸钠0.25 g/L;复合澄清剂在4个温度处理条件下的澄清结果表明,前3 d的浊度、透光率、色度等各项指标随温度变化差异显著(p<0.05),5 d后趋于平稳,从处理7 d后的澄清指标与主要成分的变化来看,10 ℃处理澄清效果最佳,浊度为1.98 NTU,透光率96.60%,酒石酸1.32 g/L、多酚含量1105 mg/L和色度值1.09;4 ℃处理的效果次之,随着温度的降低(0 ℃和-4 ℃)其澄清效果逐渐降低,但各处理温度条件下各指标也有差异。因此,适宜的复合澄清剂(明胶:皂土=1:1)在10 ℃条件下对赤霞珠葡萄酒处理5~7 d可获得良好的澄清效果。     

不同澄清剂对石榴利口酒澄清效果的研究

比较了单一澄清剂和复合澄清剂对石榴利口酒澄清效果的影响。研究表明：单一使用壳聚糖6．0g／L和膨润土6．0g／L处理石榴利口酒均能起到较好的澄清效果;复合澄清剂对石榴利口酒澄清效果较之单一澄清剂有很大提高,同时确定其在石榴利口酒澄清中的最佳组合,即：明胶0．4g／L、壳聚糖6．2g／L、膨润土6．2g／L。     

Clarification of apple juice by electroflotation

Apple Juice industry is in search of a simplified technology which enables a quick clarification and stabilisation of apple juice. This study aimed to evaluate the potential of electroflotation as an alternative for the clarification of apple juice. Clarification of apple juice by electroflotation was first done at various current densities (10, 20 and 40 mA/cm²) with and without addition of gelatin (200 mg/l). Afterwards, the electroflotation treatments were done at a current density of 20 mA/cm² with various concentrations of added gelatin (0, 50, 100 and 200 mg/l). It was shown that electroflotation treatments alone was efficient to reduce the tannin and protein contents of apple juice. However, the decrease in the protein content was in large part due to the use of pectinases prior to the electroflotation treatments. The use of gelatin in combination with the electroflotation aided in the clarification process. The highest gelatin concentration used in this study (200 mg/l) resulted in a better reduction of tannin and protein levels, while a current density of 20 mA/cm² was found to be optimal. Turbidity observed in the juices clarified with electroflotation treatments was in average lower than 10 NTU but higher than 2 NTU which is generally required to produce a stable clarified juice. Brix degree and pH of the apple juice was not affected by the electroflotation treatments while the color was improved.

Industrial relevance

The production of clarified and stable apple juice is a subject of interest for the beverages industries. The clarification step which remained long and discontinuous implied the addition of a large quantity of pectolytic enzyme and of clarifying agents (such as gelatin) to the freshly pressed juice to induce the precipitation of proteins and other suspended matter in 15–20 h. Fining treatments were followed by a separation step usually consisting of decantation and classical filtration on filter-press, or flotation by dispersed gas. The development of membrane separation processes to replace the traditional approach has enabled the automation of the whole production resulting in lower labor requirement and a considerably shorter process time than the traditional process.However, the performance of membrane separation processes is influenced by the declining permeate flux with time, which is due to membrane fouling. In some instances, permeate flux decline makes membrane separation processes unattractive for the clarification of apple juice. To our knowledge, we are the first research group to use electroflotation (EF) for clarification of apple juice. It was shown that EF treatments alone were efficient to reduce the tannin and protein contents of apple juice. In addition, the use of gelatin in combination with the EF aided in the clarification process. Turbidity observed in the juices clarified with EF treatments for 30 min was in average lower than 10 NTU. Brix degree and pH of the apple juice were not affected by the EF treatments while the color was improved.When compared to the values reported in the literature for flotation by dispersed gas, it seems that EF shows better efficiency than flotation in decreasing the juice turbidity (99% decrease for EF as compared to 90% decrease for flotation). In addition, for experiments carried out by conventional flotation larger amount of fining agent are used (70–150 mg of gelatin/l, 400–800 mg/l of silica sol and 200–500 mg/l of bentonite). For these reasons, the new process we propose is advantageous when compared to the traditional flotation approach and it should have a measurable impact on the advancements in the production of clarified apple juice. If used as a pre-treatment to ultrafiltration clarification, it is expected that it would reduce membrane fouling resulting in higher productivity.     

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.     

不同澄清剂对山葡萄酒澄清效果的影响

对不同浓度的4种澄清剂（壳聚糖、果胶酶、皂土、明胶）处理后的山葡萄酒进行澄清度（透光率）、色度、还原糖、总糖、pH、可溶性固形物含量分析,旨在探明不同浓度的4种澄清剂对山葡萄酒澄清效果及理化指标的影响,结合感官分析,确定合理可行的山葡萄酒澄清方法。结果表明,单一使用明胶和皂土对山葡萄酒澄清没有明显效果,壳聚糖最适用量为0.09%～0.15%,果胶酶最适用量为0.04%～0.08%;复合澄清剂（壳聚糖0.09%+果胶酶0.08%）在作用温度15 ℃时对山葡萄酒澄清效果最佳,透光率达到76.2%;理化性质及感官评定分析表明,复合澄清剂澄清后的山葡萄酒口感最优,感官评分为90.5分。     

小麦蛋白对樱桃酒的澄清效果

以制备的小麦澄清蛋白处理樱桃酒,通过测定澄清前、后理化性质和稳定性的变化来分析小麦澄清蛋白对 樱桃酒的澄清效果。结果表明：用50 mg/L的小麦澄清蛋白处理樱桃酒后,其浊度与澄清前相比降低了71.64%;总 酚质量浓度和黄酮质量浓度与澄清前相比差异不显著（P＞0.05）;酒精体积分数、pH值、色价值、花色苷质量浓 度、总糖质量分数和总酸质量浓度与澄清前相比变化不大。与明胶、聚乙烯吡咯烷酮、羧甲基纤维素钠相比,经 小麦澄清蛋白处理的樱桃酒先于其他3 种澄清剂在139 h时达到最低浊度2.07 NTU并保持不变。用明胶作澄清剂, 樱桃酒中总酚减少量最多,减少35.37 mg/L;用聚乙烯吡咯烷酮作澄清剂,色价值降低最高,降低0.30;用羧甲基 纤维素钠作澄清剂,花色苷减少量最多,减少0.49 mg/L。小麦澄清蛋白处理樱桃酒的最佳条件为：小麦蛋白用量 50 mg/L、搅拌速率800 r/min、搅拌时间120 min。小麦澄清蛋白具有澄清效果好、澄清速率快、安全无毒、成本低 等优点,对樱桃酒的工业生产和延长货架期具有重要意义。     

不同澄清剂对紫甘薯汁色泽及抗氧化活性的影响

研究了明胶、皂土、壳聚糖等澄清剂对紫甘薯汁澄清度、色泽及抗氧化活性的影响。试验结果表明,明胶、皂土和壳聚糖在对紫甘薯汁的澄清过程中伴随着花色苷的损失,总酚含量的减少及其抗氧化活性的降低。其中,壳聚糖引起紫甘薯汁花色苷的损失最大,即对紫甘薯汁色泽的影响最为显著。皂土导致紫甘薯汁总酚含量及其抗氧化能力下降程度最大。明胶对紫甘薯汁色泽和抗氧化活性影响最少,但是其澄清效果不佳。     

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.     

Quality of base and sparkling wines as influenced by the type of fining agent added pre-fermentation

A comparison of the effect on base wines of pre-fermentative clarification between a fining mixture (potassium caseinate, bentonite and cellulose microcrystalline) and bentonite was carried out. Fining agents were added to two grape juices from different cultivars: Macabeo and Parellada. These varietal wines are used for making sparkling wine within the appellation (certified brand of origin) Cava. Vinification was done in parallel on an industrial scale (100 000 l). The use of the fining mixture in grape juice made the fermentations more complete and gave wines with less browning ability, more foam stability time and a lower content of nitrogenous fraction, polyphenols and some volatile compounds than the wines treated with single bentonite. Sensorial analysis showed that the wines produced with the use of different fining agents had different organoleptic characteristics. In addition, the effect of fining agent added pre-fermentatively was observed on some components of sparkling wines.     

Repercussion of the clarification treatment agents before the alcoholic fermentation on volatile composition of white wines

Albariño must was clarified with two fining agents, as bentonite and silica gel. Alcoholic fermentation was carried out at semi-industrial scale, and the concentration of free monoterpenes, norisoprenoids, C₆-alcohols, higher alcohols, fatty acids, ethyl esters, and acetates was then investigated. The use of bentonite allows loss of several volatile compounds compared to wine control. In a second step, the effect of clarification–stabilization treatments with silica gel on aromatic substances was compared in order to study this influence in white wines elaborated from different aromatic varieties (Albariño and Loureira). The results showed that the use of these fining agent plays a significant role in the wine volatile composition.     

Effect of processing on post-bottling haze formation in apple juice

Post-bottling haze formation in clarified apple juice produced under a variety of processing conditions was studied. Turbidity of the juice was monitored at intervals during a 6-month storage period. Changing the pasteurization temperature of raw juice and omitting the addition of amyloglucosidase did not retard or prevent haze development. Omission of the fining procedure, however, resulted in an increase in turbidity of 1.36 NTU and visual observation of larger quantities of haze. Fining with a gelatin/bentonite ratio of 1:1 gave the least haze. Thermocoagulation treatment applied to the juice prior to ultrafiltration also did not retard or prevent haze formation. Ultrafiltration at lower processing temperatures resulted in the development of less haze. At higher temperatures an increase in turbidity of over 14 NTU was observed. The results suggest that optimization of the fining procedure and ultrafiltration could be used to retard post-bottling haze in apple juice.     

皂土处理对葡萄酒发酵及质量的影响

以霞多丽和玫瑰香为原料,通过优化和添加两种皂土处理方式,研究皂土对酒精发酵和葡萄酒质量的影响。结果表明:添加处理可增加葡萄汁中不溶性固形物含量,对最大发酵速率和总发酵时间及葡萄酒组分无明显影响;优化处理可提高葡萄汁的澄清度,降低发酵速率,延长总发酵时间,使葡萄酒的残糖含量较高。无论是添加处理还是优化处理均对葡萄汁的氨基氮含量无明显影响,因此在优化葡萄汁中添加氮素营养不能扭转发酵缓慢现象。     

青梅甘蔗复合发酵酒加工工艺

以梅浆:甘蔗汁=1∶1的混合浆为原料,研究了青梅甘蔗复合发酵酒(简称为梅酒)的关键加工工艺,具体包括:梅浆酶解条件、梅酒发酵工艺、梅酒澄清条件。结果表明,酶解的适宜条件为:酶解浓度251.5 mg/L,温度45℃,时间4 h;发酵条件为:菌种接种量5%,SO2添加量100 mg/L,初始pH3.2,发酵温度28℃;在明胶、皂土、壳聚糖3种澄清剂中,以皂土的澄清效果最佳,其最佳澄清条件为:添加量0.08 g/100 mL、温度25℃、处理10 h。     

Clarifying effect of different fining agents on mulberry wine

Fining experiments have been conducted on mulberry wine, in which five fining agents (bentonite, gelatin, casein, egg albumin and PVPP) were investigated. The effect of these agents on polyphenol content, colour intensity, antioxidant activity and aromatic profile has been determined. In general, all treatments improved the limpidity of the mulberry wines to some extent. The wine was mostly negatively affected by gelatin and led to the greatest reduction of phenol content (16.61%), colour intensity (32.26%) and antioxidant activity. Concerning aroma, the addition of PVPP, casein and bentonite both significantly altered the aroma profile. It is noteworthy that egg albumin led to the lowest diminution total phenol value (5.74%) and improvement of antioxidant capacity and colour among the tested fining agents. Furthermore, the aroma profile remained mostly unaffected by egg albumin. As consequence, the optimal fining agent for mulberry wine was egg albumin.     

不同下胶剂对蓝莓红酒下胶效果的研究

选用豌豆蛋白(INOFINEV)、颗粒皂土(BOG)、复合抗氧化澄清剂(FPR)3种下胶剂对蓝莓酒进行下胶,通过蓝莓酒沉淀物、浊度和色度确定最佳的下胶效果.研究结果表明,单一下胶实验中,BOG是适宜的下胶剂,蓝莓酒形成的沉淀物最多,紧实度最好;最佳用量为0.6 g/L,蓝莓酒浊度1.7 NTU,色度值降低9.49％.复...