Acceptability of Whey-Soy Drink Mix Prepared with Cottage Cheese Whey

Flavor score of commercially produced whey-soy drink mix containing 41% sweet whey solids was correlated with the lactic acid content of the dehydrated material (?.75). Experimental samples prepared with a 1:1 mixture of acid whey to sweet whey and neutralized acid whey showed lower initial flavor scores than a control prepared with only sweet whey. Both samples contained over 1% total lactate reported as lactic acid compared to .4% for the control. A sample prepared with a 1:5 mixture of acid to sweet whey contained .77% lactic acid. Flavor scores of this sample after 158 days storage at 37 C, although not significantly different from the control stored under similar conditions, showed a downward trend over time. Therefore, use of small amounts of acid whey in the formulation could lead to impaired storage stability as measured by flavor acceptability during prolonged storage under adverse conditions.     

乳清中乳糖的酶法水解

本文研究了Aapergillur niger CWL2NU-3乳糖酶在乳清中的应用,探讨了温度、pH、金属离子、底物浓度、酶浓度及水解时间等因素对乳清中乳糖的酶法水解速度的影响,在此基础上确定了主要影响因素,通过正交试验,获得乳清中乳糖水解的最佳工艺条件(65℃、pH4.5、乳糖15%、[E]/[L]=0.03、水解时间2.5h),在此条件下乳糖水解率为91.0%。     

以乳清为原料酶法水解乳糖条件的研究

乳糖溶解性差、甜度低,加之部分人群具有乳糖不耐症等原因,乳清中乳糖的利用率相对较低。利用β-半乳糖苷酶对乳清中的乳糖进行水解,既可以改善乳糖的溶解性能和甜度,又有利于提高乳清中乳糖的利用率。本实验通过研究乳清中乳糖的浓度、β-半乳糖苷酶的使用量、水解液温度、水解液pH对乳糖水解度的影响,确定了以乳清为原料酶法水解乳糖的适宜条件,即乳糖浓度15%、β-半乳糖苷酶的使用量为90U/g乳糖、水解液温度40℃、水解时间3h、水解液pH值6.5,在此条件下水解度为68%。     

Batch Hydrolysis of Lactose in Concentrated Whey Systems

Commercial preparations of acid and neutral β-galactosidases were assayed for their ability to hydrolyze lactose in wheys with varying total solids content. In wheys with 7.3 to 24.7% TS, at pH 4.5 and 55°C the lactose conversion obtained in 300 min with the acid lactase ranged from 92 to 75%. Similarly, the neutral lactase hydrolyzed between 92 and 79% of lactase in wheys adjusted to pH 6.5 and 35°C; however, the reaction appeared to reach its maximum after 90 min in contrast to the acid lactase.     

Partial Deacidification and Demineralization of Cottage Cheese Whey by Nanofiltration

Nanofiltration (NF) membrane processing was investigated as a method for deacidifying and demineralizing cottage cheese whey (CCW) as function of pH 3.0 to 6.5 so that it could be used in ice cream and other frozen dairy desserts. Membrane flux values after 30 min processing ranged from 7.5 to 9.0 Lm^?2hr^?1. Total processing time to produce volume concentration ratio 3 (VCR3) retentate and diafiltration against 3 volumes of water to produce DNF3 retentate ranged from 87 to 93 min at pH 3–4.35 to 180 to 210 min at pH 5.5–6.5. DNF3 retentate contained 0.33% lactic acid, 0.65% ash, 11.55% lactose and 14.47% total solids. Membrane rejection of lactic acid ranged from 31% for VCR3 retentate to 67.2% for DNF3 retentate. Membrane rejection of minerals for VCR3 and DNF3 retentates was 30% and 71%, respectively.     

Cottage Cheese Whey Ultrafiltrate Produced by Hollow Fiber Ultrafiltration,

The composition and volume of ultrafiltrate produced by hollow fiber ultrafiltration of cottage cheese whey with the Bio-Rad Bio-Fiber 50 Miniplant were studied and fitted to models. Temperature, pH, and protein concentration of the feed cheese whey, the flow rate of the feed cheese whey through the Miniplant, and the pressure differential across the membranes were the independent variables in the model fitting. Feed whey temperature and pressure differential across the membranes were the most significant variables affecting the volume of ultrafiltrate produced. Surface plots of response were generated.     

Enzymatic Lactose Hydrolysis for Prevention of Lactose Crystallization in a Whey Spread

The enzymatic lactose hydrolysis for elimination of sandiness was studied in a whey-buttermilk spread of previously optimized composition (18% fat, 12% protein, 17% lactose). Soluble enzyme preparations of either the acid (Aspergillus) or the neutral (Kluyveromyces) type were suitable for the minimum 30% hydrolysis required to prevent the lactose crystallization. Two types of acid enzymes used at either 1 mg or 2 mg per g hydrolyzed mixture produced the desired effect after 2 hr of hydrolysis at 30°C. Similar results were obtained with two types of neutral enzymes at 2 mg per g hydrolyzed mixture after either 2 or 4hr of hydrolysis at 30°C.     

Partial Demineralization of Cottage Cheese Whey Using a Heat Treatment Process

Heat treatment of concentrated cottage cheese whey ultrafiltrate resulted in loss of calcium and phosphorus. Heat treatment at 100°C for 120 min resulted in a decrease of 21% of the calcium, 14% of the phosphorus, and 7% of the magnesium. Minimal browning of the concentrate occurs after 120 min. At 120°C, minimal browning had occurred after 60 min. Levels of calcium, phosphorus and magnesium had dropped by 41%, 36%, and 20%, respectively. Forty-eight percent of the calcium, 40% of the phosphorus and 26% of the magnesium were removed by heat treatment at 140°C for 24 min. At that point, browning was minimal. Losses of sodium and potassium were negligible for all cases. A first order rate expression was found to represent the precipitation process.     

固定化渗透乳酸克鲁维酵母(Kluyveromyces Lactis)连续水解乳清的研究

研究了一种利用固定化渗透乳酸克鲁维酵母催化水解乳清中乳糖的技术,分析了制备工艺、水解条件对于固定化细胞活性的影响。结果表明,在细胞添加量为60%、交联剂为1%BaCl2,凝胶颗粒大小为1～1.5mm时,固定化细胞的活性可达到78.819 U/g,固定化细胞最适反应温度为36℃,最适pH值7.0,相对于游离细胞,固定化细胞在对温度及pH的适应性上均有所提高,具有较好的应用前景。此外初步探索了一种复合流速连续水解的工艺,即在水解不同阶段,采用了不同的流速进行水解。结果表明,这种复合流速连续水解工艺可以在一定程度上缩短水解时间,提高水解的效率。     

Calcium Chelation and Other Pretreatments for Flux Improvement in Ultrafiltration of Cottage Cheese Whey

Cottage cheese whey was treated to minimize effects of calcium on membrane fouling during ultrafiltration in a stirred Amicon cell. The treatments used were stepwise pH adjustment from 4.5 to 1.5; chelation of calcium with EDTA or citric acid; calcium chelation followed by pH adjustment to 2.5; and calcium replacement with sodium by ion exchange. All treatments resulting in elimination of free calcium improved the flux. Highest flux increase (53%) in the 8hr processing runs was for citric acid (I.25 meq/one meq Ca) after pH adjustment to 2.5. Addition of CaC1₂ decreased the flux. Confirmatory experiments with DDS-Lab 20 equipment showed 25% flux increase after treatment with either EDTA (one meq/one meq Ca) or citric acid (I.25 meq/one meq Ca) with pH adjusted to 2.5.     

Sensory Characteristics of Cottage Cheese Whey and Grapefruit Juice Blends and Changes During Processing

Studies were conducted to determine the sensory characteristics of pasteurized blends of cottage cheese whey and grapefruit juice (0%, 25%, 50%, 75% and 100% whey), and the effects of processing alternatives and storage at 3°C. A trained sensory panel rated six attributes (grapefruit, sweetness, sourness, astringency, cheesiness, saltiness). Cheesiness and saltiness increased, while sourness, astringency, sweetness, and grapefruit flavor decreased as the percentage of whey increased. Protein removal did not affect the sensory characteristics, but vacuum stripping reduced cheesiness and increased grapefruit flavor and sweetness. Lactose hydrolysis increased sweetness and decreased cheesiness in blends with more than 50% whey. The flavor of most blends was stable for 14 wk at 3°C.     

Modeling of Isothermal Diffusion of Whey Components from Small Curd Cottage Cheese During Washing

The batchwise washing of whey components from small curd cottage cheese is modeled as an isothermal diffusion process in a porous medium with several refinements to account for the whey on curd surfaces that is carried into the washing system. Three geometric approximations are considered. Apparent diffusion coefficients for total solids and lactose at 25°C are determined. Results show that diffusion from a spherical particle with consideration of whey entrained in curd interstices by capillary forces is an acceptable basis for a mass transfer model.     

切达干酪乳清结晶分离乳糖的工艺优化

以切达干酪的乳清为原料,采用浓缩结晶的方法分离乳糖,利用响应面优化结晶工艺。通过Box-Benhnken试验设计方法,在单因素实验的基础上,以结晶乳糖得率为指标,研究了结晶时间、结晶温度以及乳清pH因素及相互作用对得率的影响,得到了最佳的结晶工艺条件:结晶温度38.4℃、结晶时间24.7 h、乳清pH 5.1,此条件下,乳糖结晶得率达到最大值47.7%。     

原生质体融合选育乳清发酵生产燃料乙醇的酵母菌种

以酿酒酵母AY-5和克鲁维酵母TY-13为出发菌株进行原生质体融合选育乳清发酵优良菌种。通过对原生质体融合条件的优化获得152株初筛菌株,经麦芽糖和乳糖杜氏管试验复筛得4株融合子。对4株融合子进行乳清发酵实验,从中选出1株发酵优良的菌株R-1,与亲本比较,发酵速度明显提高。     

应用卡地干酪青霉水解乳清中蛋白质的研究

主要研究了卡地干酪青霉（P.camemberti）对乳清中蛋白质的水解作用。通过测定水解产物游离氨基酸（FAA）含量，比较霉菌添加量、pH值、水解时间对乳清中蛋白质水解度的影响，实验发现较佳的水解条件为：接种量0．5％，pH6，发酵2d。     

酶法水解乳清蛋白工艺研究

以乳清蛋白为原料,选择碱性蛋白酶水解乳清蛋白.通过四因素三水平正交试验设计方法对碱性蛋白酶水解乳清蛋白的工艺条件[酶-底浓度比(E/S),pH,水解温度,水解时间]进行优化,确定了碱性蛋白酶酶解乳清蛋白的最佳水解条件为酶-底浓度比0.05,pH8.0,反应温度60℃,水解200min,此条件下水解度为21.92％.各因素对水解度的影响主次顺序为酶-底浓度比(E/S)＞水解温度＞水解时间＞pH.     

乳清中乳碱性蛋白的分离与纯化

利用离子交换和葡聚糖凝胶层析等技术从制作干酪的副产物乳清中提取乳碱性蛋白。分别以洗脱速度、洗脱温度、洗脱液浓度为因素,进行L9(34)正交试验,最终得出各因素对离子交换树脂提取效果的影响主次顺序依次为洗脱速度＞洗脱温度＞洗脱液浓度;采用D072 强酸性阳离子交换树脂提取乳碱性蛋白的最佳洗脱条件为洗脱速度2.50mL/min、洗脱温度40℃、洗脱液浓度0.04mol/L。在该条件下的乳碱性蛋白提取率为7.55%。在制得的粗MBP 的基础上,利用Sephadex G-100 型葡聚糖凝胶,蛋白分离范围4000～150000D,对其进行纯化,测得最终纯度为83.55%。     

Effect of HTST Pasteurization of Milk, Cheese Whey and Cheese Whey UF Retentate upon the Composition, Physicochemical and Functional Properties of Whey Protein Concentrates

The effect of high temperature-short time (HTST) pasteurization of milk, Cheddar cheese whey and cheddar cheese whey ultrafiltration (UF) retentate upon the composition, physicochemical and functional properties of whey protein concentrates (WPC) was investigated. HTST pasteurization (72°C-15 sec) of milk, whey and UF retentate caused no significant differences in chemical composition of resulting WPCs. HTST pasteurization of milk and whey had no significant effect upon WPC solubility, whereas, heating UF retentate caused significant loss of WPC solubility. HTST pasteurization of milk caused a significant lowering (P<0.10) of maximum foam expansion of WPC dispersions, but HTST pasteurization of whey and UF retentate had no significant effect upon this latter parameter.     

Cottage Cheese from Ultrafiltered Skim Milk Retentates in Industrial Cheese Making

Ultrafiltered skim milk retentates were transported to a large industrial cottage cheese plant for milk supplementation leading to cottage cheese. The resulting industrial products were observed for composition, yields, whey component losses, and quality.Ten lots of small curd cottage cheese were made in vats containing up to 6593 kg skim milk. Retentate supplemented skim milks, concentrated approximately 10% (1.1:1) and 20% (1.2:1) in total protein, were very similar in initial composition to the controls. Mean cheese yield values from milks supplemented to 1.2:1 total protein were significantly higher than mean unsupplemented control milk values. Cheese yield efficiencies, per kilogram total solids, were also significantly higher in the retentate cheese but not when calculated per kilogram total protein.Total solids, total protein, and ash were higher in cottage cheese wheys from retentate supplemented cheese and were directly related to retentate supplementation concentration. Mean whey component loss per kilogram cheese exhibited significant decreases from milks of higher retentate supplementation. Retentate supplemented skim milk produced industrial cottage cheese of comparable quality to cheese made from unsupplemented control skim milks.     

乳清对马苏里拉奶酪成熟过程中蛋白质降解的影响

将乳清加入原料乳中制作乳清奶酪,并以未添加乳清的奶酪作为对照,对两种奶酪成熟过程中蛋白质降解等品质特性进行检测分析,结果表明:两种奶酪成熟期间p H值均下降,蛋白质含量均不断降低,水分活度不断下降,L*值下降,b*值先下降后小幅度上升,pH 4.6 SN和12％TCA-SN含量不断上升.但整个成熟过程中乳清奶酪的pH更...