Production of chhana by ultrafiltration

Ultrafiltration has been successfully used in the manufacture of chhana, an Indian milk product used as a base material for making sweets. The ultrafiltration behaviour of pasteurized whole milk versus severely heated whole milk, as regards the flux, energy requirement for concentration and retention coefficients, was studied. Chhana was manufactured from ultrafiltrated retentates obtained by ultrafiltration of pasteurized whole milk and that of severely heated whole milk and the process standardized with respect to the heat treatment, concentration of coagulant and temperature and pH of coagulation. An increase of 31.4% in the yield of chhana on product basis and of 16.4% on dry matter basis was achieved. Only 4.35 kg of milk was used to produce 1 kg chhana by the ultrafiltration method against 5.7 kg of milk by the conventional method. The process offers access to easy automation and control ensuring uniformity of production on a large scale.     

Lactose absorption by postweaning rats from yogurt, quarg, and quarg whey

Lactose-intolerant postweaning rats were fed experimental diets including yogurt, quargs prepared from yogurt culture and buttermilk culture, and two types of whey obtained from quarg processing. After feeding each diet for a period of 7 d, absence of blood glucose elevation and occurrence of diarrhea were used as indicators of lactose malabsorption. Blood glucose assays and absence of diarrhea indicated that yogurt and quargs prepared from yogurt and buttermilk culture were well tolerated by the rats. Wheys containing the same levels of viable organisms and lactose as the quargs caused severe symptoms of diarrhea and poor lactose absorption as indicated by no changes in blood glucose levels. Plate counts and enzyme assays of gastrointestinal contents confirmed presence of viable culture organisms and beta-galactosidase activity after feeding the two types of quarg. The availability of viable organisms, the exogenous lactase activity, and especially the slow gastric emptying may all have contributed to more efficient hydrolysis and digestion of lactose from quargs and yogurt than from the wheys.     

Cathepsin D activity in quarg

Quarg cheese was produced from raw skim milk, pasteurised skim milk, raw skim milk with rennet added and ultrafiltrated raw skim milk. Quarg was also produced from raw skim milk with pepstatin added at curd cutting and from ultrafiltration retentate of raw milk with added pepstatin. No starter bacteria were used in this model system, with the reduction of pH being achieved by addition of glucono- δ-lactone. Yields ranged between 20.25 and 23.5%, with protein levels of 13.6–15.7%. Proteolysis occurred during storage of all experimental cheese samples for 3 m at 8°C. By immunoblotting using antibodies against bovine cathepsin D, immunoreactive procathepsin D was identified in all cheese samples. Presence of cathepsin D or procathepsin D-derived activity was confirmed by a specific enzyme assay in all samples, except those which contained pepstatin. Inhibition of cathepsin D-catalysed proteolysis by pepstatin was observed in chromatograms of water-soluble extracts analysed by reverse-phase HPLC. Peptides thought to be produced as a result of cathepsin D activity were observed in cheese made from both raw and pasteurised milk, suggesting that the activity at least partially survived pasteurisation.     

Production of a banana (Musa cavendishii) extract containing no polyphenol oxidase by ultrafiltration

The objective of this research was the production of a banana extract containing no polyphenol oxidase by ultrafiltration. Banana juice was extracted after inhibition of polyphenol oxidase using a solution containing 0.15 g per 100 ml of sodium metabisulphite and 1 g per 100 ml of ascorbic acid in distilled water to avoid initial browning. Polyphenol oxidase was then retained by ultrafiltration using polysulphone membranes with a cut‐off of 20 kDaltons. Two transmembrane pressures, 600 and 800 kPa, were used but 600 kPa was preferred because of the more stable permeate flux which decreased less with time and concentration of extract. © 1999 Society of Chemical Industry     

食醋超滤澄清研究

对食醋进行了超滤澄清研究,考察了不同膜、搅拌速率、透过液通量、料液温度等对食醋超滤过程的影响,并对其中膜污染阻力进行了分级研究.结果表明,截留分子量为100kDa的PVDF超滤膜适合食醋超滤澄清,且效果显著,可使浊度从175 NTU降至0.2 NTU以下,总酸度损失率<6%、葡萄糖和乳酸则基本没有损失;随着搅拌速率的增加、透过液通量的降低以及料液温度的升高,食醋超滤澄清过程的跨膜压力随之降低,而总酸度损失率亦同样有降低趋势;膜污染阻力的分级测定显示,膜表面浓差极化层与滤饼层分别占总膜阻的38.15%和28.95%,而膜内部污染阻力几乎可以忽略;采用浓度为0.05mol/L的NaOH溶液浸泡24h,可有效清除膜污染,清洗后膜阻为新膜膜阻的98%.     

大豆混合油超滤法物理精炼

本文论述了超滤法应用于混合油物理精炼工艺，探讨了膜对混合油各组分的选择性及膜分离过程中的工艺参数。     

超滤法制取大豆浓缩蛋白

使用植酸酶对脱脂大豆粉溶液处理 ,然后稀释并用超滤膜超滤。所得膜浓缩大豆蛋白含72 5 %蛋白质 ,并且其中植酸浓度大大降低。与目前商业生产相比 ,该方法可提高蛋白得率 17%～ 2 6%。     

Recycling of poultry process wastewater by ultrafiltration

Poultry processing plants use relatively high amount of water with an average consumption of 26.5 L/bird during primary and secondary processing of live birds to meat. The used water contains proteins, fats, carbohydrates from meat, blood, skin and feathers, resulting in much higher biological oxygen demand (BOD) and chemical oxygen demand (COD). Hence the processors are required to remove majority of the soluble and particulate matter in the wastewater prior to discharge from the plant. Treatments for poultry wastewater include screening, diatomaceous earth filtration, ozonation, and chlorine dioxide. Food safety and inspection service regulations allow reconditioned water to replace potable water in prescribed ratios. Recycling of poultry wastewater by ultrafiltration improves the quality of recycled water and provides solution to water resource limitations. Ultrafiltration is basically a pressure-driven process that separates on the basis of molecular diameter. Membrane bioreactors (MBR) that integrate biological degradation of waste products with membrane filtration are also quite effective in removing organic and inorganic contaminants as well as biological entities from wastewater. Value added products like crude proteins could be separated through ultrafiltration from poultry wastewater, subsequently reducing the chemical oxygen demand. Ongoing research in membrane separation techniques involves exploration of new membrane materials and of new module design configurations to address issues of membrane fouling and treatment of waste streams containing high suspended solids or viscous wastes.Industrial relevancePoultry processing plants use large volumes of water at different stages of the process due to set policies regarding the pathogen reduction requirements in the broiler meat. Recovery of process wastewater benefits the plant by reducing fresh water demand, wastewater volume and energy consumption. Microbial safety is the primary concern in reconditioning of process wastewater. Proteins and fats which come from carcass debris and the blood are the major pollutants in the wastewater. These materials are of high nutritional value and should be recovered. The proteins and fats are difficult to harvest by conventional procedures. From an environmental and economic point of view, ultrafiltration is an efficient technique to recondition wastewater and to recover proteins and fats from it. Importantly, this technology addressed the water quantity and quality issues that have been raised in this industry by reducing primary water use and electrical energy. Though the capital costs of ultrafiltration are higher, their life cycle costs are comparable with conventional treatments. Further, foot print of ultrafiltration could be 30–50% of conventional filters with less consumption of chemicals. Hence this paper focuses upon the potential for the use of ultrafiltration membrane processing for recycling poultry process wastewater and recovery of value added products.     

超滤法提取茶多糖研究

以截留分子量为30000D的超滤膜对茶叶酶解提取液进行超滤分离,考察了操作压力、运行时间对膜渗透通量的影响;然后对由超滤截留液醇沉制取的粗多糖进行精制,考察了三氯乙酸浓度对精制过程的影响。结果表明,采用超滤法可以有效实现茶叶酶解提取液中大分子多糖与小分子多酚等活性物质的分离,三氯乙酸浓度为4%时,多糖得率34.3%,含糖量52%。     

多肽-铁超滤纯化工艺研究

采用超滤技术纯化多肽-铁,经中性蛋白酶、风味酶两次酶解后,离心10min,以原血中二价铁的含量为实验指标,在不同单因素条件下进行超滤,得到最佳单因素方案为:流速26.7×10-3L/min,pH7.5,温度20℃。其中影响实验的最重要因素为pH,其次是流速,最后为温度。进行三元二次回归正交组合设计,得到最佳的实验组合为:流速26.7×10-3L/min,pH7.5,温度20℃,最终将多肽铁的产率提高了3.26%。     

超滤浓缩大豆乳清蛋白

本文对超滤技术在浓缩大豆乳清蛋白中的应用进行初步的探索,探索压力、温度、运行时间和浓缩倍率对浓缩大豆乳清蛋白的影响,结果表明截留率在92%以上。     

超滤技术纯化大豆糖蜜中低聚糖的研究

对超滤技术纯化大豆糖蜜中的低聚糖进行了研究,探讨了pH和温度对膜分离效果的影响,确定超滤的较优条件为:选用截留相对分子量为10000的膜,pH7.0,温度20℃,采用间断全过滤的操作方式。在此条件下超滤所得的透过液澄清透亮,大分子类蛋白可完全去除,低聚糖透过率达70%。     

Analysis of caramels by capillary electrophoresis and ultrafiltration

Class I, III and IV caramels are distinguished from each other by capillary electrophoresis at pH 2.5 and 9.5. The majority of the colour is shown to be in the high molecular weight (MW) fraction of all the caramels. The high MW Class I and Class IV caramel peaks migrate with a negative charge at both pHs but the Class IV caramel also has several sharp peaks from low MW components compared to only a small neutral peak from the Class I caramels. The Class III caramels have a high MW peak which is positively charged at pH 2.5. The migration time, and hence charge, of the high MW peak of Class III caramels is shown to be related to the caramel's nitrogen content. © Crown copyright 1999     

超滤法分离纯化酪蛋白糖巨肽的研究

酪蛋白糖巨肽(Casein glycoma cropeptide,简称CGMP)是蛋白酶酶解κ-酪蛋白得到的C末端亲水性糖肽,具有多种生理功能。研究了超滤法分离纯化CGMP的条件,得到超滤的最佳条件是在室温下,压差为0.02MPa,浓缩比为8。通过此方得到了比较纯的CGMP,蛋白回收率为1.77%,糖基化程度(唾液酸/蛋白质)为70.1μg/mg,并且此方法适用于工业化生产。     

超滤浓缩对芦荟凝胶稳定性的影响研究

新鲜的芦荟凝胶经过降低pH，超滤除去芦荟中的致泻物质、纤维、细菌等，并浓缩，结果表明：pH为3．1～3．3，2～3．5倍水洗涤除致泻物质，浓缩10倍，可稳定60天以上。     

Surfactant cleaning of ultrafiltration membranes fouled by whey

A polyethersulphone ultrafiltration membrane was prepared for concentration of whey. The membrane was fouled by whey and the effect of different cleaning agents on flux recovery of the fouled membrane was studied. The optimum cleaning procedure for membrane regeneration was elucidated. The results showed that a combination of surfactants (anionic, cationic and nonionic) may be employed as the optimum cleaning agent for maximum flux recovery. The fluorescence studies revealed that the cationic surfactant interact with proteins by breaking the intra‐chain hydrophobic bonding and providing electrostatic repulsion. Changing the alkyl chain from dodecyl to hexadecyl increases the interaction of surfactant–protein. Dodecyltrimethylammonium bromide (DTAB) provided a weak interaction with whey proteins than to tetradecyltrimethylammonium bromide (TTAB) and cetyltrimethylammonium bromide (CTAB). All data obtained in this study support a surfactant–protein interaction in which hydrophobic forces play a dominant role. The nonionic surfactants poly(oxyethylene) isooctyl phenyl ether (TX‐100) and anionic surfactants SDS interact with amino acids in the inner protein structure thus denaturate tertiary protein structure and reduce hydrophobic interaction of proteins by membrane surface.     

Production and functional characterisation of antioxidative hydrolysates from corn protein via enzymatic hydrolysis and ultrafiltration

Corn protein was hydrolysed by three microbial proteases and further separated by sequential ultra-filtration to 12 hydrolysate fractions which were investigated for free radical scavenging capacity and chelating activity. The oxygen radical absorbance capacity (ORAC) of the hydrolysates varied significantly between 65.6 and 191.4μmoles Trolox equivalents (TE)/g dried weight with a small peptide fraction (NP-F3) produced by neutral protease (NP) possessing the highest antioxidant activity. The 1,1-diphenyl-2-picrylhydrazyl radical (DPPH()) scavenging activities of the hydrolysate fractions also varied significantly between 18.4 and 38.7μmoles TE/g. Two fractions (AP-F2 and AP-F3) produced by alkaline protease (AP) showed the strongest activity. However, no significant difference was detected on the chelating activity of the fractions. NP-F3, AP-F2, and AP-F3 were incorporated into ground beef to determine their effects on lipid oxidation during 15-day storage period. NP-F3 was the only fraction that inhibited lipid oxidation at both 250 and 500μg/g levels by as much as 52.9%.     

Production and fractionation of tuna by-product protein hydrolysate by ultrafiltration and nanofiltration: Impact on interesting peptides fractions and nutritional properties

The production of fish protein hydrolysates (FPH) is a promising route to add value to fish by-products due to their potential application as a source of interest peptide fractions. Using Alcalase for hydrolysis of tuna dark muscle by-product, the influence of enzyme/substrate ratio and hydrolysis time on the rate of interest peptide fractions (1–4 kDa) was studied. The rate of this fraction obtained under optimized conditions (temperature 55 °C, pH 8.5, enzyme/substrate ratio of 1% and 60 min of hydrolysis reaction) was 26%. The performance of the combined process associating ultrafiltration and nanofiltration membranes was evaluated for fractionation of produced hydrolysate in order to isolate fractions enriched in peptides of specific molecular weight (MW). The interest peptide fraction (1–4 kDa) was isolated and the positive effect of diafiltration on peptide purification process was underlined. The peptide fractions produced have a high nutritional quality which can be used in human nutrition and they have a potential for applications in aquaculture diets.     

Fouling of microfiltration and ultrafiltration membranes by natural waters

Membrane filtration (microfiltration and ultrafiltration) has become an accepted process for drinking water treatment, but membrane fouling remains a significant problem. The objective of this study was to systematically investigate the mechanisms and components in natural waters that contribute to fouling. Natural waters from five sources were filtered in a benchtop filtration system. A sequential filtration process was used in most experiments. The first filtration steps removed specific components from the water, and the latter filtration steps investigated membrane fouling by the remaining components. Particulate matter (larger than 0.45 microm) was relatively unimportant in fouling as compared to dissolved matter. Very small colloids, ranging from about 3-20 nm in diameter, appeared to be important membrane foulants based on this experimental protocol. The colloidal foulants included both inorganic and organic matter, but the greatest fraction of material was organic. When the colloidal fraction of material was removed, the remaining dissolved organic matter (DOM), which was smaller than about 3 nm and included about 85-90% of the total DOM, caused very little fouling. Thus, although other studies have identified DOM as a major foulant during filtration of natural waters, this work shows that a small fraction of DOM may be responsible for fouling. Adsorption was demonstrated to be an important mechanism for fouling by colloids.     

Removal of penicillin G from contaminated milk by ultrafiltration

Penicillin G purposedly added to whole raw milk at concentrations from .05 to .20 IU/ml was removed to undetectable levels by a combination of ultrafiltrations and permeate washes. After penicillin removal, whole milk 3:1 vol/vol concentrated retentates were reconstituted to milk with antibiotic-free permeate with little change in composition and with very good to excellent flavor. Washing 3:1 vol/vol concentrated retentates from penicillin-contaminated milks with water also removed penicillin to an undetectable level but changed the composition of product, which displayed a flat flavor.