Effects of spray drying conditions and the addition of surfactants on the foaming properties of a whey protein concentrate

Whey is the main waste by-product from dairy industry and at the same time is the major source of globular proteins. These proteins are concentrated mainly through spray drying, but high temperatures affect the foaming properties of globular protein. The addition of surfactants can have a protective role against thermal effects. The aim of this work was to optimize the spray-drying condition and surfactant concentration to obtain a whey protein concentrate (WPC) to be used in hot beverages according to the industry criteria for foaming stability. Three temperatures and three surfactant concentrations were applied, and the optimization was conducted using response surface analysis. Sensory analysis was applied to the WPC obtained under optimal conditions. The results showed that the foaming stability according to industrial criteria was attained when the spray drying was performed at 210 °C with surfactant concentration of 1.50 g/100 g. This resulted in foaming capacity of 3.80 mL, moisture content of 1.82 g/100 g and apparent density of 0.181 g/cm³. The sensory analysis suggested that aroma was related to dairy, cooked and whey and taste was related to sweet and dairy notes. In conclusion, temperature and surfactant concentration played an important role in the foaming capacity and stability of WPC.     

The effects of operating conditions on lactose crystallization in a pilot-scale spray dryer

The effects of operating conditions on the rate of drying and degree of crystallinity of lactose have been explored in a pilot-scale spray dryer. Temperature, moisture content, feed flow rate, atomizing air-flow rate, main air-flow rate and particle size have been varied to estimate the range of crystallinity of lactose obtainable in a pilot-scale spray dryer. Modulated differential scanning calorimetry (MDSC) and sorption tests (water-induced crystallization) have been used to assess the degree of crystallinity for freshly spray-dried samples. The degree of crystallinity could be varied from 18% to 72% by varying the operating conditions while allowing reasonable drying of the material. The study suggested that the use of a lower inlet temperature increased the crystallinity of the product from 25% (at 230 °C) to 60% (at 170 °C). A decrease in product crystallinity was also noted when using a lower atomizing air-flow rate. Statistical analysis with t-tests confirmed these differences to be significant with 95% confidence. The results suggest differences between small and pilot-scale spray dryers due to differences in particle sizes and drying rates.     

超滤浓缩乳清蛋白并分离乳糖的研究

采用管式超滤装置,选用切割分子量为20000的聚丙烯腈膜,对乳清进行了超滤浓缩试验。结果表明,降低乳清pH值可提高透液通量,把乳清调整至pH7．0,再离心除去不溶性钙盐,可获得最大透液透量。中性乳清经离心沉降后,在进口压力0.24MPa,温度45℃条件下浓缩180min,平均透液通量达到29．1kg／m2·h,蛋白质含量提高到2.85％,透过液中乳糖浓度变化不大。     

Crystallization behavior of lactose/sucrose mixtures during water-induced crystallization

The crystallization behavior of lactose/sucrose mixtures during water-induced crystallization was studied to gain more insight about their crystallization during storage. Solutions with different ratios of lactose and sucrose, 75:25 and 50:50, were spray dried to produce amorphous powders. The powders were kept at a controlled temperature and humidity to study their sorption–desorption behavior. X-ray diffraction and light microscopy analysis were performed to study their crystallization behavior. Two-step desorption was observed after sieving the powders as sample preparation. Sieving decreased the crystallization time for lactose/sucrose mixture 75:25 from 22 days to 2.5 days. Based on the X-ray diffraction analysis during this two-step process of water desorption, it was concluded that lactose crystallizes first and more quickly than sucrose. The degree of crystallization for the lactose crystals increases by 89% (relative to their final level of crystallinity), whereas sucrose crystals increase their level of crystallinity by only 28% during the first step of crystallization in the lactose/sucrose (75:25) mixtures. The light microscopy images also suggested that the crystallization of amorphous lactose/sucrose powders during water-induced crystallization may occur as a solution rather than in the solid phase.     

Bifidobacterium Bb-12 microencapsulated by spray drying with whey: Survival under simulated gastrointestinal conditions,tolerance to NaCl,and viability during storage

Bifidobacterium Bb-12 was microencapsulated by spray drying with whey. This present work investigated the survival of these microcapsules under simulated gastrointestinal conditions, as well as their tolerance to NaCl and their viability during storage. The results showed a small decrease in the viability of microencapsulated Bifidobacterium at low pH. In relation to the exposure of Bifidobacterium to bile, microencapsulation with whey did not protect the probiotic cells; however, the viability of the microcapsules remained >6 log cfu/g, even after 24 h of incubation at the highest bile concentration analyzed. No growth was noted with either the free cells or the microencapsulated cells on MRS-LP with NaCl. The viability of the microcapsules stored at 4 °C remained high and constant for 12 weeks. When the microcapsules were added to a dairy dessert, the probiotic count remained above 7 log cfu/g for 6 weeks. Therefore, whey is a promising encapsulating agent for Bifidobacterium Bb-12.     

Reducing the deposition of fat and protein covered particles with low energy surfaces

Deposition behavior of spray dried full cream milk, skim milk and whey particles were observed in a pilot scale dryer. Particle surface dominated with fats exhibit gradual decrease in deposition fluxes when transition from the initial adhesion to the subsequent cohesion mechanism. Whey protein, however, displayed significant differences in the adhesion and cohesion fluxes. Reduction of particle deposition on low energy chamber wall surface is more significant for the hydrophobic whey particles. Further analysis shows that the reduction in droplet–wall contact energy is larger for the more hydrophobic droplet, delineating weaker adhesion interaction. The results suggest that the hydrophobicity of the depositing particles in an important consideration when using lower chamber wall with lower surface energy. This is in addition to the effect of particle rigidity and deposition strength as reported previously.     

Milk sugars and minerals as ingredients

Lactose is the natural carbohydrate source and prebiotic compound found in the milk of mammals, but large variations in lactase activity in the small intestines of adult populations can cause problems with its use. The value of lactose can be increased by hydrolysis, but even more valuable products can be made by changing the structure of lactose and preventing its absorption in the gut. Some of these nonabsorbable lactose derivatives are already used in medical and functional food applications.
Calcium phosphate precipitation to the heat-transfer surfaces is one of the oldest problems of the dairy industry, but if precipitation is carried out in controlled conditions, the precipitate can be further processed to form milk calcium powder. Milk calcium can be used as a natural source of calcium in calcium-fortified dairy products.
The mineral and salty taste of whey has reduced its use as a food ingredient. The use of modern membrane technology offers a means of producing whey salt as a by-product of whey demineralization. These otherwise wasted minerals can then be used as a natural mineral salt. Especially interesting is the possibility of recycling the whey salt into cheese, improving its nutritional status.     

香辛料精油微胶囊化过程中油滴粒径的变化

研究了喷雾干燥法制备香辛料精油微胶囊工艺过程中各单元操作对油滴平均直径产生的影响。以及和包埋率的关系。     

肉桂醛微胶囊的制备工艺

研究了以阿拉伯树胶和麦芽糊精为壁材,喷雾干燥制备微胶囊化肉桂醛的工艺条件,探讨了壁材组成、乳化剂用量、固形物浓度,芯壁化,进风温度、进料速度、喷射压力等对微胶囊化效果的影响,经过正交试验,确定了最佳工艺条件。     

Bioutilisation of whey for lactic acid production

The disposal of whey, the liquid remaining after the separation of milk fat and casein from whole milk, is a major problem for the dairy industry, which demands simple and economical solutions. The bioconversion of lactose present in whey to valuable products has been actively explored. Since whey and whey permeates contain significant quantities of lactose, an interesting way to upgrade this effluent could be as a substrate for fermentation. Production of lactic acid through lactic acid bacteria could be a processing route for whey lactose and various attempts have been made in this direction. Immobilised cell technology has also been applied to whey fermentation processes, to improve the economics of the process. A fermentative means of lactic acid production has advantages over chemical synthesis, as desirable optically pure lactic acid could be produced, and the demand for optically pure lactic acid has increased considerably because of its use in the production of poly(lactic acid), a biodegradable polymer, and other industrial applications. This review focuses on the various biotechnological techniques that have used whey for the production of lactic acid.     

乳制品与糖尿病的饮食防控

本文综述了乳制品与糖尿病之间关系的研究进展。流行病学研究表明,乳制品对糖尿病的发生风险无不良影响,甚至有一定降低风险的作用。乳制品中的乳糖不会快速升高血糖,其反式脂肪成分并不是糖尿病的风险因子,而其中的乳清蛋白对于糖尿病患者是有利的。因此,乳制品是糖尿病患者饮食的有益组成。     

茴香油微胶囊化的喷雾干燥工艺研究

研究了茴香油喷雾干燥微胶囊化的喷雾干燥工艺。研究表明 :选用大豆分离蛋白与多糖复合作壁材并采用气流式喷雾干燥设备 ;喷雾干燥条件应为 :进料浓度 3 0 %、进风温度 195℃、出风温度 10 0± 5℃。研究结果进一步表明 :如果壁材材料改变 ,则喷雾干燥条件要作相应的改变     

喷雾干燥现状及展望

概述了我国各种类型喷雾干燥的发展状况以及与国外的差距，简述了料液雾化机理、物化性能及喷雾干燥理论研究和设计方法的最新进展，并对今后的发展方向提出了建议。     

喷雾干燥参数对小分子大豆肽的影响

本试验通过对大豆蛋白水解液进行喷雾干燥的研究,最终确定选用四级喷雾干燥(即在喷雾干燥塔内完成附聚造粒干燥)制备小分子大豆肽。研究得出在料液温度为60℃、喷雾干燥塔内热风温度为145℃、进料泵速为4r/min、进料浓度为14%、喷雾压力为14MPa和喷嘴孔径2.0mm时。制得的大豆肽可以快速溶解,并且没有抱团现象出现,颜色为淡黄色,产品透明度好。     

微胶囊化天然维生素E的研究

对制造胶囊化天然维生素E粉末的工艺和技术进行了研究。工艺过程包括乳化液的制备和喷雾干燥造粒。影响工艺及产品 因素包括原料配方，乳化工艺条件，均质压力及喷雾干燥造粒工艺条件等。性状分析及贮实验表明：微胶囊型天然维生素E的水溶性，流动性，分散性及稳定性等性能指标均好。     

奶油香精微胶囊研究

用喷雾干燥法对奶油香精微胶囊化进行了研究,探索了工艺条件,对微胶囊壁材进行了选择。