乳清蛋白提高运动能力的研究进展

从乳清蛋白不同补充形式的角度综述了乳清蛋白对改善运动人群生理指标和提升运动能力等方面的研究进展.     

乳清蛋白在运动营养中作用

该文通过对乳清蛋白成分介绍,阐明乳清蛋白对于运动营养益处,主要表现为提高免疫力、抗氧化、防止损伤与疲劳等方面,并指出运动饮料将成为乳清综合利用一个重要方向。     

乳清蛋白在运动营养方面的作用

营养对运动员的运功能力有着重要的影响。乳清蛋白中含有多种营养成分和生物活性物质,能够起到增加肌肉力量、改善机体组成、促进快速恢复、增强免疫的作用,对提高运动成绩具有重要作用。     

美国乳清蛋白在运动营养方面的作用

<正> 运动员追求的是在竞赛中表现突出或最大程度地发挥个人潜能,而营养选择会影响运动员的表现,膳食混合物也会提高运动员的表现,这一认识激发了人们对于运动营养补足剂的兴趣。研究报告表明,乳清蛋白可以给运动员提供许多独特的益处,能促进快速恢复、增强免疫、提高训练成绩。临床试验表明,在膳食中加入乳清蛋白可直接提高运动员的表现。     

乳清蛋白复合运动饮料的研制

运用运动营养学理论,研究乳清蛋白复合运动饮料的配方,确定具体的生产工艺,并以小鼠耐力试验对产品的功效性能进行评价和验证。     

补充乳清蛋白对篮球运动员竞技能力的影响

竞技体育运动对当代运动员的身体素质要求越来越高,因此需要更科学、更合理地安排饮食,为运动员提供科学合理的营养供给。篮球运动员要想在重大体育比赛中取得优异成绩,必须要参与高强度的训练和演练,这对篮球运动员的体能素质和竞技能力提出了较高的要求。常见的膳食蛋白质难以满足训练和竞赛的需要,而乳清蛋白含有丰富的生物活性成分和丰富支链氨基酸,可帮助运动员提升免疫力、缓解运动性疲劳、增加肌肉力量和抗氧化能力等,对于提高运动员综合竞技能力具有重要意义。本文介绍了乳清蛋白的营养特点,并论述了补充乳清蛋白对篮球运动员竞技能力的积极影响,以供参考。     

乳清蛋白与碱性电解质应用于运动保健固体饮料的研究

乳清蛋白含丰富的支链氨基酸和含硫氨基酸,交索与健力宝碱性电解质、复合碳水化合物、复维生素、牛磺酸等配合经一民型沸腾造粒技术,制成一种抗疲劳的运动保健固体饮料。     

乳清蛋白组分及其对骨代谢的影响

乳清蛋白是干酪加工过程中产生的副产品,由于其组成成分的异质性和丰富性,成就了其在生物学功能上的多样性。乳清蛋白中的成分主要分为两大类：骨桥蛋白、酪蛋白磷酸肽和糖巨肽属活性蛋白等乳清酸性蛋白,及IGF-I、TGF-β和EGF等生长因子、半胱氨酸蛋白酶抑制剂C、HMG样蛋白和激肽原片断等乳清碱性蛋白。它们通过参与破骨细胞介导的骨吸收和成骨细胞介导的骨形成或者改变钙离子的溶解状态等方式影响骨代谢,在延缓由于年龄增长或雌激素减退引起的骨丢失、增强骨骼生物力度等方面发挥积极作用。     

健康宝贝＆漂亮妈妈——乳清蛋白来帮忙

十月怀胎期间,准妈妈不仅需要注重均衡营养,也要避免热量摄取过量,这就需要各位准妈妈擦亮眼睛,选择优质的食物,既要保证自身和宝宝的营养所需,又要尽可能减少不必要的消化和代谢负担,为产后恢复打下良好的基础。     

Production of a high gel strength whey protein concentrate from cheese whey

In order to develop a process for the production of a whey protein concentrate (WPC) with high gel strength and water-holding capacity from cheese whey, we analyzed 10 commercially available WPC with different functional properties. Protein composition and modification were analyzed using electrophoresis, HPLC, and mass spectrometry. The analyses of the WPC revealed that the factors closely associated with gel strength and water-holding capacity were solubility and composition of the protein and the ionic environment. To maintain whey protein solubility, it is necessary to minimize heat exposure of the whey during pretreatment and processing. The presence of the caseinomacropeptide (CMP) in the WPC was found to be detrimental to gel strength and water-holding capacity. All of the commercial WPC that produced high-strength gels exhibited ionic compositions that were consistent with acidic processing to remove divalent cations with subsequent neutralization with sodium hydroxide. We have shown that ultrafiltration/diafiltration of cheese whey, adjusted to pH 2.5, through a membrane with a nominal molecular weight cut-off of 30,000 at 15 degrees C substantially reduced the level of CMP, lactose, and minerals in the whey with retention of the whey proteins. The resulting WPC formed from this process was suitable for the inclusion of sodium polyphosphate to produce superior functional properties in terms of gelation and water-holding capacity.     

Enzymatic hydrolysis of heated whey: iron-binding ability of peptides and antigenic protein fractions

This study evaluated the influence of various enzymes on the hydrolysis of whey protein concentrate (WPC) to reduce its antigenic fractions and to quantify the peptides having iron-binding ability in its hydrolysates. Heated (for 10 min at 100°C) WPC (2% protein solution) was incubated with 2% each of Alcalase, Flavourzyme, papain, and trypsin for 30, 60, 90, 120, 150, 180, and 240 min at 50°C. The highest hydrolysis of WPC was observed after 240 min of incubation with Alcalase (12.4%), followed by Flavourzyme (12.0%), trypsin (10.4%), and papain (8.53%). The nonprotein nitrogen contents of WPC hydrolysate followed the hydrolytic pattern of whey. The major antigenic fractions (β-lactoglobulin) in WPC were degraded within 60 min of its incubation with Alcalase, Flavourzyme, or papain. Chromatograms of enzymatic hydrolysates of heated WPC also indicated complete degradation of β-lactoglobulin, α-lactalbumin, and BSA. The highest iron solubility was noticed in hydrolysates derived with Alcalase (95%), followed by those produced with trypsin (90%), papain (87%), and Flavourzyme (81%). Eluted fraction 1 (F-1) and fraction 2 (F-2) were the respective peaks for the 0.25 and 0.5 M NaCl chromatographic step gradient for analysis of hydrolysates. Iron-binding ability was noticeably higher in F-1 than in F-2 of all hydrolysates of WPC. The highest iron contents in F-1 were observed in WPC hydrolysates derived with Alcalase (0.2 mg/kg), followed by hydrolysates derived with Flavourzyme (0.14 mg/kg), trypsin (0.14 mg/kg), and papain (0.08 mg/kg). Iron concentrations in the F-2 fraction of all enzymatic hydrolysates of WPC were low and ranged from 0.03 to 0.05 mg/kg. Fraction 1 may describe a new class of iron chelates based on the reaction of FeSO₄·7H₂O with a mixture of peptides obtained by the enzymatic hydrolysis of WPC. The chromatogram of Alcalase F-1 indicated numerous small peaks of shorter wavelengths, which probably indicated a variety of new peptides with greater ability to bind with iron. Alcalase F-1 had higher Ala (18.38%), Lys (17.97%), and Phe (16.58%) concentrations, whereas the presence of Pro, Gly, and Tyr was not detected. Alcalase was more effective than other enzymes at producing a hydrolysate for the separation of iron-binding peptides derived from WPC.     

Astringency of bovine milk whey protein

Whey protein solutions at pH 3.5 elicited an astringent taste sensation. The astringency of whey protein isolate (WPI), the process whey protein (PWP) that was prepared by heating WPI at pH 7.0, and the process whey protein prepared at pH 3.5 (aPWP) were adjusted to pH 3.5 and evaluated by 2 sensory analyses (the threshold method and the scalar scoring method) and an instrumental analysis (taste sensor method). The taste-stimulating effects of bovine and porcine gelatin were also evaluated. The threshold value of astringency of WPI, PWP, and aPWP was 1.5, 1.0, and 0.7 mg/mL, respectively, whereas the gelatins did not give definite astringency. It was confirmed by the scalar scoring method that the astringency of these proteins increased with the increase in protein concentration, and these proteins elicited strong astringency at 10 mg/mL under acidic conditions. On the other hand, the astringency was not elicited at pH 3.5 by 2 types of gelatin. A taste sensor gave specific values for whey proteins at pH 3.5, which corresponded well to those obtained by the sensory analysis. Elicitation of astringency induced by whey protein under acidic conditions would be caused by aggregation and precipitation of protein molecules in the mouth.     

The effect of bleaching agent on the flavor of liquid whey and whey protein concentrate

The increasing use and demand for whey protein as an ingredient requires a bland-tasting, neutral-colored final product. The bleaching of colored Cheddar whey is necessary to achieve this goal. Currently, hydrogen peroxide (HP) and benzoyl peroxide (BPO) are utilized for bleaching liquid whey before spray drying. There is no current information on the effect of the bleaching process on the flavor of spray-dried whey protein concentrate (WPC). The objective of this study was to characterize the effect of bleaching on the flavor of liquid and spray-dried Cheddar whey. Cheddar cheeses colored with water-soluble annatto were manufactured in duplicate. Four bleaching treatments (HP, 250 and 500 mg/kg and BPO, 10 and 20 mg/kg) were applied to liquid whey for 1.5 h at 60°C followed by cooling to 5°C. A control whey with no bleach was also evaluated. Flavor of the liquid wheys was evaluated by sensory and instrumental volatile analysis. One HP treatment and one BPO treatment were subsequently selected and incorporated into liquid whey along with an unbleached control that was processed into spray-dried WPC. These trials were conducted in triplicate. The WPC were evaluated by sensory and instrumental analyses as well as color and proximate analyses. The HP-bleached liquid whey and WPC contained higher concentrations of oxidation reaction products, including the compounds heptanal, hexanal, octanal, and nonanal, compared with unbleached or BPO-bleached liquid whey or WPC. The HP products were higher in overall oxidation products compared with BPO samples. The HP liquid whey and WPC were higher in fatty and cardboard flavors compared with the control or BPO samples. Hunter CIE Lab color values (L*, a*, b*) of WPC powders were distinct on all 3 color scale parameters, with HP-bleached WPC having the highest L* values. Hydrogen peroxide resulted in a whiter WPC and higher off-flavor intensities; however, there was no difference in norbixin recovery between HP and BPO. These results indicate that the bleaching of liquid whey may affect the flavor of WPC and that the type of bleaching agent used may affect WPC flavor.     

胶原蛋白在运动食品中的应用及其对运动员的影响

众所周知,运动员在运动过程中会极大消耗体能,但运动员摄入特殊的营养素,可以发挥他们的最大运动能力。近年来运动营养研究发现,胶原蛋白因具有高吸收利用率、提高免疫、锁住钙质、补充水分等特性而被格外关注。本文首先介绍了胶原蛋白的结构特点,对胶原蛋白的生物学功能加以概述,重点探讨了胶原蛋白对运动员的影响及在在运动食品领域的应用,从而为胶原蛋白功能产品的研究和开发提供理论参考。     

Efficiency of removal of whey protein from sweet whey using polymeric microfiltration membranes

Our objective was to measure whey protein removal percentage from separated sweet whey using spiral-wound (SW) polymeric microfiltration (MF) membranes using a 3-stage, 3× process at 50°C and to compare the performance of polymeric membranes with ceramic membranes. Pasteurized, separated Cheddar cheese whey (1,080 kg) was microfiltered using a polymeric 0.3-μm polyvinylidene (PVDF) fluoride SW membrane and a 3×, 3-stage MF process. Cheese making and whey processing were replicated 3 times. There was no detectable level of lactoferrin and no intact α- or β-casein detected in the MF permeate from the 0.3-μm SW PVDF membranes used in this study. We found BSA and IgG in both the retentate and permeate. The β-lactoglobulin (β-LG) and α-lactalbumin (α-LA) partitioned between retentate and permeate, but β-LG passage through the membrane was retarded more than α-LA because the ratio of β-LG to α-LA was higher in the MF retentate than either in the sweet whey feed or the MF permeate. About 69% of the crude protein present in the pasteurized separated sweet whey was removed using a 3×, 3-stage, 0.3-μm SW PVDF MF process at 50°C compared with 0.1-μm ceramic graded permeability MF that removed about 85% of crude protein from sweet whey. The polymeric SW membranes used in this study achieve approximately 20% lower yield of whey protein isolate (WPI) and a 50% higher yield of whey protein phospholipid concentrate (WPPC) under the same MF processing conditions as ceramic MF membranes used in the comparison study. Total gross revenue from the sale of WPI plus WPPC produced with polymeric versus ceramic membranes is influenced by both the absolute market price for each product and the ratio of market price of these 2 products. The combination of the market price of WPPC versus WPI and the influence of difference in yield of WPPC and WPI produced with polymeric versus ceramic membranes yielded a price ratio of WPPC versus WPI of 0.556 as the cross over point that determined which membrane type achieves higher total gross revenue return from production of these 2 products from separated sweet whey. A complete economic engineering study comparison of the WPI and WPPC manufacturing costs for polymeric versus ceramic MF membranes is needed to determine the effect of membrane material selection on long-term processing costs, which will affect net revenue and profit when the same quantity of sweet whey is processed under various market price conditions.     

富含磷脂的乳清蛋白粉改善小鼠记忆力功能研究

摘 要：目的 探讨富含磷脂的乳清蛋白粉对小鼠记忆力的影响。方法 选取288只SPF级昆明种雄性小鼠,分别进行两次试验,每次试验144只。每次试验分为3批,每批48只,随机分为空白模型对照组和磷脂乳清蛋白粉低、中、高剂量组。连续给予受试物灌胃30 d后,分别进行小鼠跳台行为学实验、避暗行为学实验、水迷宫行为学实验。结果 两次跳台实验,中、高剂量组与模型对照组比较均能减少测试期错误次数（P<0.05）;第一次避暗实验高剂量组、第二次避暗实验中剂量组与模型对照组比较重测期错误潜伏期延长（P<0.05）、错误次数减少（P<0.05）。各剂量组与模型对照组比较小鼠脑组织ACh含量升高（P<0.05）,AChE活力降低（P<0.01）。结论 两次实验结果一致,表明富含5%磷脂的乳清蛋白粉通过调节改善小鼠中枢胆碱能系统从而改善小鼠记忆力。通过本实验可以为开发磷脂乳清蛋白粉改善记忆功能食品提供实验基础和开发依据。     

The effect of acidification of liquid whey protein concentrate on the flavor of spray-dried powder

Off-flavors in whey protein negatively influence consumer acceptance of whey protein ingredient applications. Clear acidic beverages are a common application of whey protein, and recent studies have demonstrated that beverage processing steps, including acidification, enhance off-flavor production from whey protein. The objective of this study was to determine the effect of preacidification of liquid ultrafiltered whey protein concentrate (WPC) before spray drying on flavor of dried WPC. Two experiments were performed to achieve the objective. In both experiments, Cheddar cheese whey was manufactured, fat-separated, pasteurized, bleached (250 mg/kg of hydrogen peroxide), and ultrafiltered (UF) to obtain liquid WPC that was 13% solids (wt/wt) and 80% protein on a solids basis. In experiment 1, the liquid retentate was then acidified using a blend of phosphoric and citric acids to the following pH values: no acidification (control; pH 6.5), pH 5.5, or pH 3.5. The UF permeate was used to normalize the protein concentration of each treatment. The retentates were then spray dried. In experiment 2, 150 μg/kg of deuterated hexanal (D₁₂-hexanal) was added to each treatment, followed by acidification and spray drying. Both experiments were replicated 3 times. Flavor properties of the spray-dried WPC were evaluated by sensory and instrumental analyses in experiment 1 and by instrumental analysis in experiment 2. Preacidification to pH 3.5 resulted in decreased cardboard flavor and aroma intensities and an increase in soapy flavor, with decreased concentrations of hexanal, heptanal, nonanal, decanal, dimethyl disulfide, and dimethyl trisulfide compared with spray drying at pH 6.5 or 5.5. Adjustment to pH 5.5 before spray drying increased cabbage flavor and increased concentrations of nonanal at evaluation pH values of 3.5 and 5.5 and dimethyl trisulfide at all evaluation pH values. In general, the flavor effects of preacidification were consistent regardless of the pH to which the solutions were adjusted after spray drying. Preacidification to pH 3.5 increased recovery of D₁₂-hexanal in liquid WPC and decreased recovery of D₁₂-hexanal in the resulting powder when evaluated at pH 6.5 or 5.5. These results demonstrate that acidification of liquid WPC80 to pH 3.5 before spray drying decreases off-flavors in spray-dried WPC and suggest that the mechanism for off-flavor reduction is the decreased protein interactions with volatile compounds at low pH in liquid WPC or the increased interactions between protein and volatile compounds in the resulting powder.