雪莲果低聚果糖粗提液除杂工艺的研究

选用石灰乳-磷酸法对低聚果糖粗提液进行除杂,石灰乳-磷酸法除杂的最佳工艺条件按工艺目的可分为2种:石灰乳调后的pH值11.5,加入石灰乳后的温度40℃,磷酸调后的pH值7,加入磷酸后的温度80℃,除杂效果好,色值可达到0.581;石灰乳调后的pH值11,加入石灰乳后的温度40℃,磷酸调后的pH值7,加入磷酸后的温度90℃,低聚果糖损失率低,仅为5.45%。     

活性炭-新磷酸钙对玉米芯低聚木糖脱色工艺优化

采用活性炭-新磷酸钙体系对高温蒸煮玉米芯酶法制备的低聚木糖进行脱色工艺研究。经过单因素试验和响应面分析,得出玉米芯低聚木糖脱色最佳工艺条件为:活性炭添加量2.00 g/L、氢氧化钙添加量3.00 g/L,脱色温度49℃,脱色时间31 min,初始pH 4.6。此时,低聚木糖脱色率可达到90.88%,还原糖损失率为5.16%。     

菊芋中提取菊粉的纯化工艺研究

采用石灰乳-磷酸法除杂和脱色剂脱色,对菊芋菊粉粗提液进行纯化研究。结果表明:石灰乳-磷酸法对菊粉粗提液除杂的最佳工艺条件为:pH12.0,温度60℃,时间10min,在此最佳条件下体系的透光率从46.5%上升到87.3%;比较几种脱色剂的脱色效果,活性炭的脱色效果最好;当活性炭用量为0.7g/100mL(除杂液),脱色温度80℃,脱色时间30min,透光率高达96.7%;当活性炭用量为0.3g/100mL(除杂液),脱色温度40℃,脱色时间10min,菊粉损失率仅为4.05%。     

甜菊糖溶液活性炭脱色工艺研究

为解决甜菊糖产品的颜色问题,选用活性炭对甜菊糖苷溶液进行脱色,并对甜菊糖溶液的脱色率和甜菊糖的损失率进行研究。先通过单因素试验初步确定活性炭的添加条件及添加量,在脱色效果达到的情况下针对甜菊糖的损失率进行正交试验,对活性炭添加比例、溶液温度、吸附时间、pH值对溶液脱色率和甜菊糖损失率的影响进行试验,证明各种因素对脱色效果和甜菊糖损失的影响不同,活性炭的添加比例影响因素最大,其次是时间,再次是温度,影响最小的是pH值。单因素试验和正交试验确定最佳工艺条件为:最佳活性炭添加比例为1%,最佳温度10℃,最佳时间为0.5h,最佳pH值为7.0,产品吸光值达到标准要求,甜菊糖损失率为2.72%。     

影响漆酶对活性染料皂洗废液脱色活性的因素

将漆酶应用于染液及皂洗废液的脱色降解中。实验发现,漆酶对0.1 g/L活性红BES纯染液脱色的最佳工艺条件为：漆酶用量1.25 g/L,pH值6.5,温度60 ℃,时间25 min。漆酶对含金属偶氮结构的活性染料脱色活性最好,对单偶氮、双偶氮、蒽醌结构的次之;对铜酞菁结构的几乎没有脱色效果。盐（硫酸钠）和肥皂对漆酶脱色活性抑制作用较小,但马丙的抑制作用较大。为提高漆酶对马丙皂洗废液的脱色效果,可通过加入添加剂进行改善,加入0.01 mol/L 的CaCl2后马丙皂洗废液的脱色率可由30.14%提高至51.62%,其他阳离子表面活性剂和硫酸铜的加入也会对漆酶脱色效果略有增强,但非离子或阴离子表面活性剂却不能。     

变性淀粉在印染废水处理中的应用研究

以阳离子淀粉为絮凝剂,加入PAC(聚合氯化铝),在考虑温度、pH值等因素的影响下,研究其对印染废水的处理效果。本实验以90mg阳离子淀粉配合6mgPAC分别处理50ml印染废水,其脱色率和浊度去除率都可达100%。实验结果表明该絮凝剂配合对印染废水处理效果较理想。     

脱色工艺对鱼皮胶原肽品质的影响

利用复合酶通过酶解方法制备罗非鱼皮胶原肽,考察活性炭、大孔吸附树脂对胶原肽的脱色效果。以脱色率和肽损失率为指标,通过正交试验进行工艺优化,结果表明:在pH 4.5、活性炭添加量2%(m/V)、脱色时间60min、蛋白浓度50mg/mL的条件下,活性炭脱色效果最佳,脱色率可达92.66%,肽损失率为11.23%;而大孔吸附树脂在最佳脱色条件下,脱色率只有83.02%,肽损失率却高达30.77%,脱色效果明显不及活性炭。根据胶原肽分子量分布和氨基酸组成分析结果发现:经活性炭、大孔吸附树脂脱色后,鱼皮胶原肽中分子量500~1 000Da组分比例明显减少,His、Tyr和Phe等氨基酸含量显著下降。     

黑豆豆腐替代脂肪对肉丸品质特性的影响

本文将黑豆豆腐作为脂肪替代品应用于肉丸的生产中,通过测定肉糜蒸煮损失及乳化稳定性、肉丸感官评价、基本成分、电子鼻、质构、色泽、出品率、pH、微观结构等指标,研究黑豆豆腐添加量（0、4%、8%、12%、16%、20%）对肉丸品质特性的影响,从而为低脂黑豆豆腐肉丸产品的开发提供可行性建议。结果表明:与对照组相比,肉糜的蒸煮损失率、水分损失率、脂肪损失率随着黑豆豆腐添加量的增加逐渐降低。当黑豆豆腐添加量为12%时,肉丸感官评分最高,整体可接受性最好。随着黑豆豆腐添加量的增加,肉丸的脂肪含量逐渐降低,蛋白质、水分、灰分含量增加;肉丸硬度、咀嚼性逐渐增大,弹性、胶黏性呈先增大后减小的趋势;L*值、a*值逐渐减小,b*值增加,出品率和pH呈先上升后下降的趋势。当黑豆豆腐添加量为12%时,肉丸出品率最高,pH最大。电子鼻主成分分析结果显示:不同黑豆豆腐添加量的肉丸样品间气味存在明显差异。扫描电镜结果表明:加入黑豆豆腐能明显提高肉丸内部结构的均匀性,改善整体品质。因此,12%的黑豆豆腐添加量制作的肉丸综合品质最佳。     

棒杆菌51~#对阳离子艳红X-5GN染料脱色条件的研究

从6株高效脱色菌株中选出对阳离子艳红X-5GN染料脱色效果最好的51~#菌株;考察了不同碳源、氮源、染料浓度、pH值、培养时间对51~#菌株脱色效果的影响,结果表明在菌液加量为5%和培养温度30℃时,该菌株对阳离子艳红X-5GN染料最佳脱色条件:以3%葡萄糖为碳源及1%尿素为氮源,染料浓度为75mg/L,pH为7,培养时间12小时,对阳离子艳红X-5GN染料脱色率达95.7%。     

活性炭对紫贻贝蛋白酶解液脱色效果的影响

利用活性炭对紫贻贝蛋白的酶解液进行脱色,以活性炭添加量、溶液pH、脱色时间和脱色温度为试验因素,感官评定、脱色率和氨基酸损失率为综合考察指标,采用单因素试验和正交试验对紫贻贝蛋白酶解液的脱色工艺条件进行研究。结果表明,活性炭的最佳脱色条件为活性炭添加量0.6%,pH 3,脱色时间20min,脱色温度20℃。该条件下,酶解液的脱色率、氨基酸损失率、感官评分分别为81.6%、19.4%、8.8。因此,活性炭可用于紫贻贝酶解液的脱色,脱色后的酶解液可用于制备热反应海鲜味香精。     

Effect of increasing the colloidal calcium phosphate of milk on the texture and microstructure of yogurt

The effect of increasing the colloidal calcium phosphate (CCP) content on the physical, rheological, and microstructural properties of yogurt was investigated. The CCP content of heated (85°C for 30 min) milk was increased by increasing the pH by the addition of alkali (NaOH). Alkalized milk was dialyzed against pasteurized skim milk at approximately 4°C for 72 h to attempt to restore the original pH and soluble Ca content. By adjustment of the milk to pH values 7.45, 8.84, 10.06, and 10.73, the CCP content was increased to approximately 107, 116, 123, and 128%, respectively, relative to the concentration in heated milk. During fermentation of milk, the storage modulus (G′) and loss tangent values of yogurts were measured using dynamic oscillatory rheology. Large deformation rheological properties were also measured. The microstructure of yogurt was observed using fluorescence microscopy, and whey separation was determined. Acid-base titration was used to evaluate changes in the CCP content in milk. Total Ca and casein-bound Ca increased with an increase in the pH value of alkalization. During acidification, elevated buffering occurred in milk between pH values 6.7 to 5.2 with an increase in the pH of alkalization. When acidified milk was titrated with alkali, elevated buffering occurred in milk between pH values 5.6 to 6.4 with an increase in the pH of alkalization. The high residual pH of milk after dialysis could be responsible for the decreased contents of soluble Ca in these milks. The pH of gelation was higher in all dialyzed samples compared with the heated control milk, and the gelation pH was higher with an increase in CCP content. The sample with highest CCP content (128%) exhibited gelation at very high pH (6.3), which could be due to alkali-induced CN micellar disruption. The G′ values at pH 4.6 were similar in gels with CCP levels up to 116%; at higher CCP levels, the G′ values at pH 4.6 greatly decreased. Loss tangent values at pH 5.1 were similar in all samples except in gels with a CCP level of 128%. For dialyzed milk, the whey separation levels were similar in gels made from milk with up to 107% CCP but increased at higher CCP levels. Microstructure of yogurt gels made from milk with 100 to 107% CCP was similar but very large clusters were observed in gels made from milk with higher CCP levels. By dialyzing heated milk against pasteurized milk, we may have retained some heat-induced Ca phosphate on micelles that normally dissolves on cooling because, during dialysis, pasteurized milk provided soluble Ca ions to the heated milk system. Yogurt texture was significantly affected by increasing the casein-bound Ca (and total Ca) content of milk as well as by the alkalization procedure involved in that approach.     

Rennet-induced gelation of calcium and phosphate supplemented skim milk subjected to CO2 treatment

A Doehlert design was performed to study the effect of calcium and phosphate supplementation at 0 to 25 mmol/kg and 0 to 16 mmol/kg, respectively, on the rennet gelation of reconstituted skim milk subjected to pH-reversible CO(2) acidification. Supplemented reconstituted skim milk samples were acidified to pH 5.80 by the addition of CO(2) under pressure and depressurized under vacuum to restore the initial pH value. The second-order polynomial models satisfactorily predicted the effect of salt addition on the micellar molar Ca:P ratio and the average diameter of the casein micelles, whereas only trends were used in the analysis of the rennet-clotting behavior of salt-supplemented, CO(2)-treated milk. Whether added Ca was the most determinant factor on the micellar molar Ca:P ratio, added Pi (a mixture of Na(2)HPO(4) and NaH(2)PO(4)) was the most determinant factor on the other responses studied, and its effect was most pronounced when Ca was simultaneously added. By comparison with control samples, changes observed in this study were essentially due to salt supplementation and not to the CO(2) treatment. Therefore, this CO(2) treatment could be considered as an entirely reversible treatment rather than only pH-reversible, and predictions might be applied to untreated milk. In the case of Ca-supplemented milk, the micellar molar Ca:P ratio increased, the average micellar diameter decreased, and the rennet-clotting properties were improved, whereas opposite effects were observed upon Pi supplementation. Since modification of the micellar molar ratio is the result of change in the chemical composition of micellar calcium phosphate, the effect of calcium and phosphate supplementation on the rennet clotting of milk was found to be also dependent on the nature of the interaction between caseins and colloidal calcium phosphate.     

High-pressure structuring of milk protein concentrate: Effect of pH and calcium

In this study, we investigated the effect of pH and calcium on the structural properties of gels created by high-pressure processing (HPP, 600 MPa, 5°C, 3 min) of milk protein concentrate (MPC, 12.5% protein). The pH level of the MPC was varied between 6.6 and 5.1 by adding glucono-δ-lactone (GDL), and the calcium content was varied from 24 to 36 mg of Ca/g of protein by adding calcium chloride. The rheological properties and microstructure of the pressure-treated MPC were assessed. The pressurization treatments and analytical testing were conducted in triplicate. Data were analyzed statistically using one-way ANOVA with Tukey's honestly significant difference post hoc tests. A pressurization time of 3 min was sufficient to induce gel formation in MPC at pH 6.6, so it was used throughout the study. Adjusting either pH or calcium affected the structure of the HPP-created milk protein gels, likely by influencing electrostatic interactions and shifting the calcium–phosphate balance. Gels were formed after pressurization of MPC at pH above 5.3, and increasing the pH from 5.3 to 6.6 resulted in stronger gels with higher values of elastic moduli (G′). At neutral pH (6.6), adding calcium to MPC further increased G′. Scanning electron microscopy showed that reducing pH or adding calcium resulted in more porous, aggregated microstructures. These findings demonstrate the potential of HPP to create a variety of structures using MPC, facilitating a new pathway from dairy protein ingredients to novel, gel-based, high-protein foods, such as puddings or on-the-go protein bars.     

Mineral and casein equilibria in milk: effects of added salts and calcium-chelating agents

We have investigated the effects of adding a range of mineral salts and calcium-chelating agents on the distribution of casein and minerals between the non-pelleted and pelleted phases of milk obtained upon centrifugation at 78000 g for 90 min. Adding CaCl2 or mixtures of NaH2PO4 and Na2HPO4 to reconstituted skim milk (90 g milk solids/kg) at pH 6.65 increased both pelleted casein and pelleted calcium phosphate. Opposite effects were obtained by adding citrate or EDTA. The change in pelleted calcium phosphate was not simply related to casein release from the micelle. Upon adding 5 mmol EDTA/kg milk, 20% of the pelleted Ca, 22% of the pelleted phosphate and 5% of the micellar casein were removed. Increasing the concentration of EDTA to 10 mmol/kg milk decreased the pelleted Ca by 44% and the pelleted phosphate by 46%, and caused 30% of the micellar casein to be released. The effects of adding phosphate, citrate or EDTA at pH 6.65, followed by the addition of CaCl2, demonstrated the reversibility of the dissolution and formation of the micellar calcium phosphate. There were limits to this reversibility that were related to the amount of colloidal calcium phosphate removed from the casein micelles. Adding CaCl2 to milk containing > or = 20 mmol EDTA or > or = 30 mmol citrate/kg milk did not result in complete reformation of casein micelles. Light-scattering experiments confirmed that the dissolution of moderate amounts of colloidal calcium phosphate had little effect on micellar size and were reversible, while the dissolution of larger amounts of colloidal calcium phosphate resulted in large reductions in micellar size and was irreversible.     

Changes in the proportions of soluble and insoluble calcium during the ripening of cheddar cheese

In cheese, the concentration and form of residual Ca greatly influences texture. Two methods were used to determine the proportions of soluble (SOL) and insoluble (INSOL) Ca in Cheddar cheese during 4 mo of ripening. The first method was based on the acid-base buffering curves of cheese and the second was based on the extraction of the aqueous phase ("juice") of cheese under high pressure and determining the concentration of SOL Ca in the juice using atomic absorption spectroscopy. When cheese was acidified there was a strong buffering peak at pH approximately 4.8, which was due to the solubilization of residual colloidal calcium phosphate (CCP) of milk that remained in cheese as INSOL Ca phosphate. The area of this buffering peak in cheese was expressed as a percentage of the original area of this peak in milk and was used to estimate the concentration of residual INSOL Ca phosphate in cheese. There were no significant differences between the 2 methods. The proportions of INSOL Ca in cheese decreased from approximately 73 to approximately 58% between d 1 and 4 mo. These methods will be useful techniques to study the role of Ca in cheese texture and functionality.     

Effect of sodium citrate on structure-function relationships of Cheddar cheese

The objective of this study was to determine the effect of sodium citrate on the structure and functionality of Cheddar cheese. The hypothesis was that citrate (sodium citrate) injection would affect cheese properties mainly through its effect on bound calcium (calculated as the difference between total calcium and the water-soluble calcium content of a cheese extract). A 9-kg block of Cheddar cheese was made, vacuum-packaged, and then stored for 2 wk at 4 degrees C. After storage, the cheese was cut into 0.5- to 0.6-kg blocks that were vacuum-packaged and stored for 1 wk at 4 degrees C prior to injection. Cheese blocks were then high-pressure injected with a buffer solution (pH 5.27) containing 40% (wt/ wt) citric acid trisodium dihydrate and 6.25% (wt/wt) anhydrous citric acid, from zero (control) to five times (successive injections performed 24 h apart). Increased citric acid content of cheese from 0.22 (uninjected) to 1.39% (after five injections) caused phosphate solubilization. Thus, the calculated bound phosphate content of cheese decreased from 0.54 to 0.45 mmol/g of protein. However, unexpectedly, the soluble calcium content decreased from 0.34 (control) to 0.28 mmol/g of protein (after five injections), whereas the bound calcium content remained unchanged (0.42 mmol/g of protein). The decrease in soluble calcium probably resulted from the formation and concentration of crystals in the cheese surface, which was not included in samples for analysis, and from the expulsion of serum from within the cheese. Higher concentration of solutes in the water phase of cheese would increase the volume of serum, but the cheese had limited holding capacity and serum was expelled. Citrate injection increased the sodium content of cheese from 0.63 to 0.93%, but it had no effect on cheese pH (5.2). After five injections, the protein matrix expanded, occupying an increased area of cheese matrix (83 vs. 78%). Even though citrate injection had no effect on bound calcium, and thus the rate and extent of cheese flow were unaffected, increased phosphate solubilization, and possibly decreased ionic calcium content, resulted in expansion of the protein matrix and increased cheese hardness.     

Bioavailability of calcium and physicochemical properties of calcium-fortified buffalo milk

Buffalo milk was fortified with calcium at the rate of 50 mg calcium/100 ml milk using calcium chloride, calcium lactate and calcium gluconate, and the resulting decrease in pH was restored to its original value by adding disodium phosphate. The maximum heat stability of calcium-fortified buffalo milk remained slightly lower than that of unfortified milk. Calcium gluconate-fortified milk had the highest heat stability, bioavailability of calcium, partitioning of calcium in the dissolved state and viscosity, and the least curd tension compared to other fortified milk, without any adverse impact on sensory properties. The bioavailability of calcium and heat stability was lowest in the case of buffalo milk fortified with calcium chloride.     

Physicochemical characterisation of calcium phosphates prepared from milk ultrafiltrates: Effect of the mineral composition

This study deals with the precipitation of calcium phosphate in permeates removed from milks at different pH (6.7, 5.2 and 4.6). An overall high yield of precipitation of calcium and phosphate (70–80%, respectively) was obtained for all precipitates with Ca/P molar ratios close to 1.5. The suspended milk‐derived calcium phosphate (MDCP) precipitates had 8–14 μm size and ?14 to ?28 mV zeta potential. The dried MDCP precipitates were identified as amorphous calcium phosphate (ACP), stable over 18 months of storage at room temperature.     

再生纤维造纸废水物化除钙试验

通过正交试验筛出钙离子去除实验中最佳组合药剂,并考察单一因素对试验的影响,最终确定试验方案.调解废水pH值确定为10左右,以25r/min搅拌3min,加入PAFC作为混凝剂,投加量为25mg/L,并投加阳性助凝剂PAM,投加量为6mg/L,此时控制转速在15r/min,搅拌时间控制在5min,搅拌完毕静置10min后...     

Impact of source and level of calcium fortification on the heat stability of reconstituted skim milk powder

Calcium enrichment of food and dairy products has gained interest with the increased awareness about the importance of higher calcium intake. Calcium plays many important roles in the human body. Dairy products are an excellent source of dietary calcium, which can be further fortified with calcium salts to achieve higher calcium intake per serving. However, the addition of calcium salts can destabilize food systems unless conditions are carefully controlled. The effect of calcium fortification on the heat stability of reconstituted skim milk was evaluated, using reconstituted skim milks with 2 protein levels: 1.75 and 3.5% (wt/wt) prepared using low and high heat powders. Calcium carbonate, phosphate, lactate, and citrate were used for fortification at 0.15, 0.18, and 0.24% (wt/wt). Each sample was analyzed for solubility, heat stability, and pH. The addition of phosphate and lactate salts lowered the pH of milk, citrate did not have any major effect, and carbonate for the 1.75% protein samples increased the pH. In general, changes in solubility and heat stability were associated with changes in pH. Calcium addition decreased the solubility and heat stability. However, interestingly, the presence of carbonate salt greatly increased the heat stability for 1.75% protein samples. This is due to the neutralizing effect of calcium carbonate when it goes into solution. The results suggested that the heat stability of milk can be affected by the type of calcium salt used. This may be applied to the development of milk-based calcium enriched beverages.