Physical properties of ice cream containing milk protein concentrates

Two milk protein concentrates (MPC, 56 and 85%) were studied as substitutes for 20 and 50% of the protein content in ice cream mix. The basic mix formula had 12% fat, 11% nonfat milk solids, 15% sweetener, and 0.3% stabilizer/emulsifier blend. Protein levels remained constant, and total solids were compensated for in MPC mixes by the addition of polydextrose. Physical properties investigated included apparent viscosity, fat globule size, melting rate, shape retention, and freezing behavior using differential scanning calorimetry. Milk protein concentrate formulations had higher mix viscosity, larger amount of fat destabilization, narrower ice melting curves, and greater shape retention compared with the control. Milk protein concentrates did not offer significant modifications of ice cream physical properties on a constant protein basis when substituted for up to 50% of the protein supplied by nonfat dry milk. Milk protein concentrates may offer ice cream manufacturers an alternative source of milk solids non-fat, especially in mixes reduced in lactose or fat, where higher milk solids nonfat are needed to compensate other losses of total solids.     

Increasing the protein content of ice cream

Vanilla ice cream was made with a mix composition of 10.5% milk fat, 10.5% milk SNF, 12% beet sugar, and 4% corn syrup solids. None of the batches made contained stabilizer or emulsifier. The control (treatment 1) contained 3.78% protein. Treatments 2 and 5 contained 30% more protein, treatments 3 and 6 contained 60% more protein, and treatments 4 and 7 contained 90% more protein compared with treatment 1 by addition of whey protein concentrate or milk protein concentrate powders, respectively. In all treatments, levels of milk fat, milk SNF, beet sugar, and corn syrup solids were kept constant at 37% total solids. Mix protein content for treatment 1 was 3.78%, treatment 2 was 4.90%, treatment 5 was 4.91%, treatments 3 and 6 were 6.05%, and treatments 4 and 7 were 7.18%. This represented a 29.89, 60.05, 89.95, 29.63, 60.05, and 89.95% increase in protein for treatment 2 through treatment 7 compared with treatment 1, respectively. Milk protein level influenced ice crystal size; with increased protein, the ice crystal size was favorably reduced in treatments 2, 4, and 5 and was similar in treatments 3, 6, and 7 compared with treatment 1. At 1 wk postmanufacture, overall texture acceptance for all treatments was more desirable compared with treatment 1. When evaluating all parameters, treatment 2 with added whey protein concentrate and treatments 5 and 6 with added milk protein concentrate were similar or improved compared with treatment 1. It is possible to produce acceptable ice cream with higher levels of protein.     

冰淇淋中奶粉替代品的研究

从考察产品的感官指标和理化性能入手,采用玉米淀粉、大豆蛋白、糊精、变性淀粉等原料替代奶粉,对冰淇淋生产的配方进行了试验,筛选出了用植物性原料替代奶粉生产冰淇淋的最佳配方。     

搅打充气对搅打奶油流变特性的影响

研究了搅打充气对搅打奶油流变特性的影响,分析其变化规律及探讨搅打充气与搅打奶油结构之间的内在联系。结果表明:搅打奶油属于假塑性流体,其表观黏度、屈服应力、触变性和黏弹性(G~*)均随搅打充气进行而增加,而相对恢复率呈先增大后减小趋势。在蠕变-回复测试中,蠕变柔量随搅打充气进行逐渐减小;推迟时间先增大后减小,到了搅打过度阶段又重新增大;回复率呈先增大后减小趋势。     

豆奶冰淇淋的工艺研究

用豆奶和牛奶结合制作冰淇淋,关键是去除豆腥味。本文从浸豆、磨浆、配方选择等方面进行了探讨。     

Effect of substituting whey cream for sweet cream on the textural and rheological properties of cream cheese

In the manufacture of cream cheese, sweet cream and milk are blended to prepare the cream cheese mix, although other ingredients such as condensed skim milk and skim milk powder may also be included. Whey cream (WC) is an underutilized fat source, which has smaller fat droplets and slightly different chemical composition than sweet cream. This study investigated the rheological and textural properties of cream cheeses manufactured by substituting sweet cream with various levels of WC. Three different cream cheese mixes were prepared: control mix (CC; 0% WC), cream cheese mixes containing 25% WC (25WC; i.e., 75% sweet cream), and cream cheese mixes with 75% WC (75WC; i.e., 25% sweet cream). The CC, 25WC, and 75WC mixes were then used to manufacture cream cheeses. We also studied the effect of WC on the initial step in cream cheese manufacture (i.e., the acid gelation process monitored using dynamic small amplitude rheology). Acid gels were also prepared with added denatured whey proteins or membrane proteins/phospholipids (PL) to evaluate how these components affected gel properties. The rheological, textural, and sensory properties of cream cheeses were also measured. The WC samples had significantly higher levels of PL and insoluble protein compared with sweet cream. An increase in the level of WC reduced the rate of acid gel development, similar to the effect of whey phospholipid concentrate added to mixes. In cream cheese, an increase in the level of added WC resulted in significantly lower storage modulus values at temperatures <20°C. Texture results, obtained from instrumental and sensory analyses, showed that high level of WC resulted in significantly lower firmness or hardness values and higher stickiness compared with cream cheeses made with 25WC or CC cream cheeses. The softer, less elastic gels or cheeses resulting from the use of high levels of WC are likely due to the presence of components such as PL and proteins from the native milk fat globule membrane. The use of low levels of WC in cream cheese did not alter the texture, whereas high levels of WC could be used if manufacturers want to produce more spreadable products.     

Effects of buttermilk powders on emulsification properties and acid tolerance of cream

Emulsifying properties and acid tolerance are 2 of the most important characteristics of cream. The effects of the buttermilk component, especially its phospholipids, on the emulsifying properties and acid tolerance of cream were investigated in this study. Two buttermilks with differing phospholipid contents and skimmed milk were used to evaluate the effects of phospholipids on the aforementioned parameters. The mean diameter of fat globules and the cream viscosity were used as indicators of emulsifying properties. Acid tolerance was evaluated by studying the effect of citric acid on the maximum viscosity of cream. This was tested by adding 400 μL of 10% (w/w) citric acid solution to cream every minute and simultaneously measuring pH and viscosity. In 45% and 40% fat cream systems, buttermilk, and especially that with higher phospholipid content, improved the emulsifying properties and acid tolerance of the cream. The components of buttermilk could alter the properties of the surface of fat globules, thereby altering the emulsification properties of the cream. However, neither of the tested buttermilks affected the emulsifying properties and acid tolerance of lower-fat (35% and 30%) cream systems. Emulsifying components exist in proportionately larger amounts in lower-fat creams, which could render the emulsifying properties resistant to change. The number of fat globules may also influence acid-induced changes in viscosity. The addition of phospholipids or lysophospholipids did not improve the acid tolerance of creams, a finding that may be attributable to the formation of complexes of phospholipids and protein. PRACTICAL APPLICATION: The findings presented herein demonstrate the ability to improve the acid tolerance of cream using materials derived from milk. Implementing these findings appropriately may result in a high-quality cooking cream.     

酶在普洱茶膏加工工艺中的应用

本文以氨基酸、茶多糖、茶多酚含量变化为指标,研究不同酶处理对普洱茶膏中呈味物质含量的影响,优化酶的作用条件,并对优化后的茶膏进行感官评定。结果表明:在相同酶浓度条件下,风味蛋白酶水解茶叶蛋白能力显著强于中性蛋白酶(p<0.01),在两种酶添加量都为45 U/g时,茶汤氨基酸增长率都达到最高,分别为28.49%、15.19%;在复配蛋白酶浓度为27 U/g,中性蛋白酶与风味蛋白酶比例为1∶2时,两种蛋白酶协同效果最佳,极显著高于同浓度单一酶作用效果(p<0.01),茶汤氨基酸增长率达到22.07%;不同糖酶水解茶叶糖类能力强弱排序为:植物水解酶>果胶酶>纤维素酶,三者差异显著(p<0.05),在植物水解酶添加量为0.6%时,茶汤中茶多糖增长率高达82.45%;多酚氧化酶对茶汤中茶多酚的转化影响很小,茶汤中茶多酚下降范围在0.32%至4.55%。优化后的茶膏感官品质有了较大提升,优化工艺合理、可行。      

蛋白质用量对粉末植脂奶油品质的影响

研究了蛋白质用量对植脂奶油乳浊液性质、喷雾干燥效果以及粉末植脂奶油搅打性能和流变特性的影响。结果表明:当蛋白质用量从0.9%提高到2.1%时,脂肪部分聚结率急剧降低到0.9%,乳浊液的脂肪球粒径d4,3从0.47%减小到0.37%,而粘度从170c P升高到291c P,喷雾干燥的粉末得率提高,但粉末分散性降低;粉末植脂奶油搅打过程中的脂肪部分聚结率也减小,搅打起泡率降低,当蛋白质用量为0.9%时搅打起泡率最大,达到325.38%,其弹性模量G′和粘性模量G″都较高,分别可到达7000Pa和900Pa,泡沫的粘弹性好。      

热处理和调节pH改性乳清蛋白浓缩物对搅打稀奶油加工性质的影响

通过热处理和调节p H对乳清蛋白浓缩物80(Whey protein concentrate,WPC80)进行改性处理,并将改性后的WPC80添加至低脂稀奶油中,以改善其搅打性质。结果表明调节WPC80溶液的p H为3,在80℃下加热15min时具有最佳的溶解性和起泡性,相同p H条件下,不同的热处理时间会对溶解性和起泡性产生不同的影响;将热处理和p H改性后WPC80加入搅打稀奶油中,研究发现不同热处理时间,p H为5改性的WPC80可以显著提高搅打稀奶油的打发率(p<0.05),但是p H为7处理的WPC80使稀奶油的泡沫稳定性增加了154.67%~193.42%。因此可通过热处理和调节p H改性的WPC80来提高低脂稀奶油的搅打特性,且此操作方法简单易行。      

Effect of double homogenization and whey protein concentrate on the texture of ice cream

Ice cream samples were made with a mix composition of 11% milk fat, 11% milk solids-not-fat, 13% sucrose, 3% corn syrup solids (36 dextrose equivalent), 0.28% stabilizer blend, or 0.10% emulsifier and vanilla extract. Mixes were high temperature short time pasteurized at 80 degrees C for 25 s, homogenized at 141 kg/cm2 pressure on the first stage and 35 kg/cm2 pressure on the second, and cooled to 3 degrees C. The study included six treatments from four batches of mix. Mix from batch one contained 0.10% emulsifier. Half of this batch (treatment 1), was subsequently frozen and the other half (upon exiting the pasteurizer) was reheated to 60 degrees C, rehomogenized at 141 kg/cm2 pressure on the first stage and 35 kg/cm2 pressure on the second (treatment 2), and cooled to 3 degrees C. Mix from batch two contained 0.28% stabilizer blend. Half of this batch was used as the control (treatment 3), the other half upon exiting the pasteurizer was reheated to 60 degrees C, rehomogenized at 141 kg/cm2 pressure on the first stage and 35 kg/cm2 pressure on the second (treatment 4), and cooled to 3 degrees C. Batch three, containing 0.10% emulsifier and 1% whey protein concentrate substituted for 1% nonfat dry milk, upon exiting the pasteurizer was reheated to 60 degrees C, rehomogenized at 141 kg/cm2 pressure on the first stage and 35 kg/cm2 pressure on the second (treatment 5), and cooled to 3 degrees C. Batch four, containing 0.28% stabilizer blend and 1% whey protein concentrate substituted for 1% nonfat dry milk, upon exiting the pasteurizer was reheated to 60 degrees C, rehomogenized at 141 kg/ cm2 pressure on the first stage and 35 kg/cm2 pressure on the second (treatment 6), and cooled to 3 degrees C. Consistency was measured by flow time through a pipette. Flow time of treatment 3 was greater than all treatments, and the flow times of treatments 4 and 6 were greater than treatments 1, 2, and 5. Flow time was increased in ice cream mix by the addition of stabilizer. Double homogenization lowered ice cream mix flow time in the presence of stabilizer, but no difference in flow time was observed without stabilizer addition. Treatment 4 had a lower mean ice crystal size at 10 d postmanufacture compared with treatment 3; however, overall texture acceptability between treatments 3 and 4 was similar. Mean ice crystal size of treatment 6 was less at 18 wk postmanufacture compared with treatment 3; however, overall texture acceptability for treatments 3, 4, and 6 was similar. Mean ice crystal sizes of treatments 1, 2, and 5 were greater at 10 d and 18 wk compared with treatment 3. Sensory evaluation indicated that treatments 3, 4, and 6 had higher mean scores for icy, coldness intensity, and creaminess than treatments 1, 2, and 5 at 10 d and 18 wk postmanufacture.     

不同处理方法对醇变性大豆蛋白溶解特征影响的研究

通过不同的处理方法对醇变性大豆蛋白(ASP)进行改性。分别考察了高速剪切处理、加热处理、酸处理和碱处理对醇变性大豆蛋白溶解特征的影响。实验结果表明,高速剪切处理能提高醇变性大豆蛋白的溶解性;高速剪切和加热处理过的醇变性大豆蛋白溶解时,随着温度的升高溶出的聚集体会增多,而酸和碱处理后的情况则相反。     

无水奶油和BL-41的比例对淡奶油稳定性的影响

研究了无水奶油和BL-41两种油脂之间不同的比例对淡奶油粒径分布、界面蛋白含量、脂肪部分聚结率及表观粘度的影响,并在此基础上探讨了其作用机理。研究结果表明,随着BL-41比例的不断增大,淡奶油的上层粒径d3,2、脂肪部分聚结率和表观粘度呈先增大后减小的趋势,在无水奶油∶BL-41为17.5∶17.5时达到最大值,而界面蛋白含量则先降低后升高,在无水奶油∶BL-41为17.5∶17.5时达到最小值。此外,随着储存时间的延长,上层粒径d3,2、脂肪部分聚结率和表观粘度均逐渐增大,而界面蛋白含量则逐渐降低。      

Effect of processing on nutritive values of milk protein

Milk is an essential source of nutritionally excellent quality protein in human, particularly in vegan diet. Before consumption, milk is invariably processed depending upon final product requirement. This processing may alter the nutritive value of protein in a significant manner. The processing operations like thermal treatment, chemical treatment, biochemical processing, physical treatments, nonconventional treatments, etc. may exert positive or negative influence on nutritional quality of milk proteins. On one side, processing enhances the nutritive and therapeutic values of protein while on other side intermediate or end products generated during protein reactions may cause toxicity and/or antigenicity upon consumption at elevated level. The review discusses the changes occurring in nutritive quality of milk proteins under the influence of various processing operations.     

南极磷虾油磷脂富集工艺的优化

借鉴水化脱胶原理,对南极磷虾油磷脂富集工艺进行优化。通过单因素实验考察了反应溶液类型、质量分数、加入量,反应温度,反应时间及搅拌速度对南极磷虾油磷脂富集效果及富集后各功能成分的影响,得到南极磷虾油磷脂富集的最佳工艺条件为南极磷虾油中加入4倍南极磷虾油磷脂量的2%柠檬酸溶液、反应温度60 ℃、搅拌速度60 r/min、反应时间30 min。在最佳条件下磷脂富集效果明显,分离得到的磷脂溶液经冻干后磷脂含量可达70.78%,EPA和DHA含量分别为151.93 mg/g和113.70 mg/g;而分离得到的甘油三酯中虾青素含量最高可达780.49 mg/kg。     

Effect of seasonal variation on the properties of whipping cream,soft cheese and skim milk powder in the UK

Whipping cream, skim milk powder and soft cheese were produced throughout the year. Whipping cream manufactured in spring and winter produced significantly higher overrun and better serum stability, and whipping time was related to buffering capacity of raw milk. Heat stability of reconstituted skim milk powder (RSMP) at 9% total solids (TS) was greater in summer and autumn, and >25% TS throughout the year. It was positively related to the protein content of raw milk, but negatively with fat. In contrast to other dairy products, no significant effect of season on the properties of soft cheese was found.     

改性大豆分离蛋白-磷脂复合物对冰淇淋品质的影响

针对大豆分离蛋白(SPI)取代部分乳粉生产冰淇淋,产品膨胀率低、易融化、口感较硬和有豆腥味等问题,本实验采用超高压改性大豆分离蛋白(USPI)、大豆分离蛋白-磷脂复合物(SPI-PLW)和超高压均质改性大豆分离蛋白-磷脂复合物(USPI-PLW)分别替代乳粉生产冰淇淋,研究了不同改性条件的大豆蛋白对冰淇淋浆料的静态流变学、膨胀率、融化率、硬度和微观结构的影响。通过对比研究得出,以USPI-PLW为原料制作成的冰淇淋的各项标准都优于其它类型的大豆分离蛋白冰淇淋。USPI-PLW冰淇淋融化率为33.17%,膨胀率可达86.86%,较传统低脂冰淇淋融化率降低26.86%,膨胀率提高了94.84%,且储藏硬化后无较大冰晶,相对于传统冰淇淋口感更绵软。     

摄食不同来源磷脂对大鼠脂质代谢及脑内磷脂脂肪酸组成的影响

研究了摄食不同来源磷脂对大鼠脂质代谢及其脑内磷脂脂肪酸组成的影响。雄性SD大鼠按体重随机分为大豆油对照组(添加9%)、牛乳磷脂组(添加5%)、大豆磷脂组(添加5%)、蛋黄磷脂组(添加5%),喂食3周。检测了血清总胆固醇(TC)、甘油三酯(TG)、高密度脂蛋白胆固醇(HDL-C)、游离脂肪酸(FFA)及肝脏TC、TG、磷脂(PL)的含量,并用气相色谱法测定了脑内磷脂脂肪酸的组成变化。结果显示:与大豆油对照组相比,3种磷脂均不同程度提高了大鼠体重、脏器指数,蛋黄磷脂效果显著;3种磷脂不同程度降低了血清TC、TG和FFA含量,牛乳磷脂降低血清FFA显著,大豆磷脂降低血清TC、TG显著,蛋黄磷脂降低FFA显著,大豆磷脂显著提升了血清HDL-C含量;3种磷脂不同程度降低了肝脏TC、TG、PL含量,牛乳磷脂与大豆磷脂降低肝脏TG、TC显著,而蛋黄磷脂降低肝脏TG显著;3种磷脂对脑内磷脂脂肪酸组成的影响各不相同,牛乳磷脂显著提高了脑内磷脂饱和脂肪酸含量,而大豆磷脂和蛋黄磷脂提高了DHA等多不饱和脂肪酸含量。研究表明,3种磷脂均有降血脂、肝脂作用,以大豆磷脂作用尤为明显,大豆磷脂和蛋黄磷脂的益智作用可能优于牛乳磷脂。     

开菲尔酸豆乳冰淇淋的研制

以豆乳代替部分牛乳并用开菲尔进行发酵,研制出开菲尔酸豆乳冰淇淋。选择煮浆时间、豆粉奶粉比例、白砂糖添加量、复合乳化稳定剂添加量、老化时间和凝冻档位作为单因素进行梯度实验,对发酵时间、接种量和发酵温度进行三因素三水平L9（33）正交实验,确定开菲尔酸豆乳冰淇淋的最佳工艺为:取浸泡好的大豆,与水按照1∶11的比例进行磨浆,过滤,沸腾后煮浆5 min,制得豆乳;以豆浆重量为基准,加入8%豆粉、5%奶粉、16%白砂糖和0.65%复合乳化稳定剂,倒入制浆机中搅拌并杀菌,待均质后的料液冷却到38℃加入料液总质量0.2%的开菲尔发酵剂,38℃发酵8 h,得到发酵乳;将发酵乳置于4℃老化缸中老化4 h,然后将料液倒入冰淇淋机器设置成三档（凝冻温度-7℃）,制得开菲尔酸豆乳冰淇淋。