花青素加工贮藏稳定性的改善及应用研究进展

花青素是一类广泛存在于果品蔬菜等植物性食品中的水溶性类黄酮色素,不仅为食品提供了丰富的颜色, 而且其呈现的抗氧化、抗炎、抗肿瘤等生理活性使其成为功能性食品研究开发的热点。由于花青素不稳定,其在食 品饮料和膳食补充剂中的应用受到限制。本文在广泛查阅文献的基础上,综述了近年来改善花青素加工贮藏稳定性 的方法和技术,重点论述了共色作用、复合作用及载体包埋等技术方法在提升花青素加工贮藏稳定性方面的进展, 以期为花青素的深入研究和工业化利用提供参考。     

Oxidative Stability of Anhydrous Milkfat Microencapsulated in Whey Proteins

The chemical stability was studied on anhydrous milkfat (AMF) encapsulated in whey protein isolate (WPI) and WPI combined with lactose (1:1 w/w WPI/L). AMF-containing microcapsules, as well as bulk milkfat, were stored at 20°C with light, 40°C without light, and 50°C with and without light for up to 12 mo. Milkfat oxidation was monitored by oxygen uptake in headspace and hexanal accumulation. In all cases, AMF oxidation was significantly limited by microencapsulation in WPI or WPI/L. Whey proteins are effective microencapsulating agents.     

热处理对液态乳中乳清蛋白的影响研究进展

牛乳中的乳清蛋白主要包括β-乳球蛋白、α-乳白蛋白、牛血清白蛋白和免疫球蛋白。在牛乳加工过程中,热处理会使乳中乳清蛋白发生变性,影响了乳清蛋白的结构和活性,进而降低了牛乳的营养价值。本文对乳业发达国家液态乳的主要加工方式以及热处理过程对4种乳清蛋白的影响进行了综述。     

Stability of Reconstituted Whey Protein Concentrates to Ultra-Heat-Treatment Processing

Reconstituted undenatured whey protein concentrates (WPC) at pH values below 7.3 were unstable to direct UHT processing, with plant blockage and/or sedimentation in the product being observed. Heat treatment of reconstituted WPC (3.5% protein) improved stability slightly. Addition of 0.25% disodium hydrogen ortho-phosphate di-hydrate to reconstituted WPC before pre-heat treatment at 85°C for 5 min improved stability to UHT processing, with no blockage of the plant or sedimentation being encountered down to pH 6.6. Addition of ortho-phosphate to reconstituted WPC, either after pre-heat treatment or without pre-heat treatment, did not improve stability. Incorporation of the ortho-phosphate/pre-heat treatment steps during normal WPC manufacture improved stability of the product to UHT processing.     

Carotene Degradation and Isomerization during Thermal Processing: A Review on the Kinetic Aspects

Kinetic models are important tools for process design and optimization to balance desired and undesired reactions taking place in complex food systems during food processing and preservation. This review covers the state of the art on kinetic models available to describe heat-induced conversion of carotenoids, in particular lycopene and β-carotene. First, relevant properties of these carotenoids are discussed. Second, some general aspects of kinetic modeling are introduced, including both empirical single-response modeling and mechanism-based multi-response modeling. The merits of multi-response modeling to simultaneously describe carotene degradation and isomerization are demonstrated. The future challenge in this research field lies in the extension of the current multi-response models to better approach the real reaction pathway and in the integration of kinetic models with mass transfer models in case of reaction in multi-phase food systems.     

Thermal Aggregation of Whey Proteins in Model Solutions as Affected by Casein/Whey Protein Ratios

Model solutions (32.5 g protein/L) prepared from milk, ultrafiltration permeate, and whey protein isolate were adjusted at pH 6.7 to casein:whey protein (C:W) ratios of 80:20, 60:40, 40:60,20:80, and 0:100. Heating was performed in test tubes at 95 °C for 5 min. Observations of the heated suspensions revealed the occurrence of heterogeneous particulates from the existing casein micelles complexed with denatured whey proteins and from aggregates essentially consisting of denatured whey proteins. The proportion of whey protein aggregates increased as C:W was changed from 80:20 to 20:80. The results from this study confirmed that heat-induced aggregates were formed not only from casein micelles but also from heat-denatured whey proteins.     

Effects of pH and Calcium on Thermal Behavior of Isolated Whey Proteins

Heat stability of 0.2%α-lactalbumin (α-la) was studied up to pH 5.0 in normal and pH 7.0 in decalcified permeates. Heating 0.4%β-lactoglobulin (β-lg) resulted in rapid flocculation before reaching 93 °C at all pH levels, except 6.5–7.0, for permeates with varying Ca content. When both isolated whey protein fractions were heated together (0.2%α-la and 0.4%β-lg) in regular or decalcified permeates, precipitation characteristics of β-lg did not change. However, some α-la appeared to co-precipitate with β-lg at pH 6.0 and below regardless of Ca.     

亚硝酸盐在烤翅加工过程中的渗透规律及其热稳定性研究

试验以鸡翅根为原料,研究了亚硝酸盐在真空滚揉和低温静腌过程中的渗透规律以及在热风烘制和高温烤制过程中亚硝酸盐添加量及工艺参数对其热稳定性的影响。结果表明:在烤翅加工过程中,原料通过真空滚揉获得一定的亚硝酸盐内渗量,其内渗量随时间以指数方式增长,且鸡翅根整体渗透速率常数随亚硝酸盐添加量增大而增大;亚硝酸盐含量在低温静腌过程中少量损失,在热风烘制和高温烤制过程中大幅减少,通过滚揉渗入鸡翅根中的亚硝酸盐;经静腌、烘制和烤制后,只有5.92%~7.87%以亚硝酸盐(以湿基计)的形式存在,低于国家标准规定的最高限量(30 mg/kg);亚硝酸盐添加量、滚揉时间、静腌时间、烘烤温度对鸡翅根中亚硝酸盐的含量影响显著(p0.05),高温能够提高亚硝酸盐的降解速率。     

Carrageenan Effects on Thermal Stability of Meat Proteins

Meat myofibrillar protein (MP) gels and ground pork were used as model systems for studying thermal transition temperatures. Addition of up 2% of κ, ι, or λ carrageenan (CGN) to MP caused a very slight change in the thermal denaturation of the meat proteins. Three transition temperatures were found in ground pork samples, which were characteristic of myosin (59.4°C), sarcoplasmic proteins (67.8°C), and actin (82.4°C). Mixtures of high ionic strength had lower thermal transition peaks. CGN did not cause major shifts in transition temperatures, suggesting that molecular interactions between CGN and meat proteins did not occur.     

Changes in the Hydrophobicity and Functionality of Whey during the Processing of Whey Protein Concentrates

Cheddar cheese whey was ultrafiltered to yield whey protein concentrates (80% WPC). The retentates were heated at 64 or 72°C for 1.5 set or received no heat treatment. Changes in composition and hydrophobicity during processing were related to WPC functionality. Heating at 72°C decreased retentate hydrophobic@ and had a detrimental affect of WPC functionality, while heating at 64°C did not. Day to day variation in the milk supply and processing conditions did not affect hydrophobicity; but the unit operations did have an effect. Ultrafiltration increased the alkane binding values of the retentate compared to the whey. Spray drying the retentate increased surface hydrophobicity and decreased alkane binding values of the WPC.     

肉类热加工过程中有害物质的形成与控制研究进展

肉类在煎炸、烧烤、蒸煮等加热过程中会产生令人愉悦的香气,但同时也伴随着多种有害物质的产生,如杂环胺、丙烯酰胺、反式脂肪酸、多环芳烃类等,这些物质会对人体健康造成极大危害.因此,探究肉类产品热加工过程中有害物质的成因及控制尤为重要.本文综述上述有害物质在肉类加热过程中的形成机理,总结上述有害物质现有的检测方法及控制手段,...     

不同加工方式对甜菜红素稳定性的影响研究进展

甜菜红素是一类含氮的水溶性色素,由于其有独特的色泽、高安全性和多种生物活性成为近年来研究的热点。甜菜红素作为天然色素已经被批准在食品工业中使用。该文对甜菜红素的合成途径、生物活性进行简要的总结,着重分析不同加工方式对甜菜红素稳定性的影响。同时,简要综述目前研究中的局限性,旨在为未来农产品加工过程中甜菜红素的保护提供参考。     

Whey Changes during Processing Determined by Near Infrared Spectroscopy

We assessed the potential application of near infrared (NIR) spectrophotometry using a remote optic fiber probe for the development of calibrations. We evaluated the heat denaturation of whey proteins, the chemical composition of a whey protein concentrate (WPC) during production, and the degree of hydrolysis (DH) of whey proteins during trypsin hydrolysis. Partial least square (PLS) calibrations were developed for these applications and were related to a variety of products and processing conditions, so as to increase their reliability. NIR has potential applications in real time analysis for whey processing lines.     

Modifying the Functional Properties of Egg Proteins Using Novel Processing Techniques: A Review

Egg proteins can be used in a wide range of food products, owing to their excellent foaming, emulsifying, and gelling properties. Another important functional property is the susceptibility of egg proteins to enzymatic hydrolysis, as protein digestion is closely related to its nutritional value. These functional properties of egg proteins are likely to be changed during food processing. Conventional thermal processing can easily induce protein denaturation and aggregation and consequently reduce the functionality of egg proteins due to the presence of heat‐labile proteins. Accordingly, there is interest from the food industry in seeking novel nonthermal or low‐thermal techniques that sustain protein functionality. To understand how novel processing techniques, including high hydrostatic pressure, pulsed electric fields, ionizing radiation, ultraviolet light, pulsed light, ultrasound, ozone, and high pressure homogenization, affect protein functionality, this review introduces the mechanisms involved in protein structure modification and describes the structure–functionality relationships. Novel techniques differ in their mechanisms of protein structure modification and some have been shown to improve protein functionality for particular treatment conditions and product forms. Although there is considerable industrial potential for the use of novel techniques, further studies are required to make them a practical reality, as the processing of egg proteins often involves other influencing factors, such as different pH and the presence of other food additives (for example, salts, sugar, and polysaccharides).     

Comparative Study on Heat Stability and Functionality of Camel and Bovine Milk Whey Proteins

Heat stability, emulsifying, and foaming properties of camel whey have been investigated and compared with that of bovine whey. Camel whey is similar to bovine whey in composition, but is deficient in β-lactoglubulin (β-LG), a major component of bovine whey. Whether the deficiency in β-LG will affect stability and functional properties is not yet known. Substantial information on the functional properties of bovine milk whey proteins is available; however, there is little research done on functional properties of camel whey proteins. Therefore, the objective of this study was to investigate the heat stability, emulsifying, and foaming characteristics of camel whey proteins. Calorimetric studies showed no significant difference in heat stability between bovine and camel whey proteins in liquid form. Upon drying, thermograms indicated that the 2 proteins are different in composition and thermal stability. The difference is represented in the absence of β-LG and the occurrence of protein denaturation peak at a lesser temperature in camel whey. The first marginal thermal transition in bovine whey appeared at 81°C, followed by 2 other transitions at 146 and 198°C. For camel whey, the transitions appeared at 139, 180, and 207°C respectively. The first marginal denaturation peak in bovine whey is due to β-LG, which is essentially absent in camel whey, while the second peak is due to the mixture of α-lactalbumin, serum albumin, and possibly part of the partially stabilized β-LG structure during the denaturation process. Because camel whey is deficient in β-LG, the denaturation peak at 139 must be due to the mixture of α-lactalbumin and camel serum albumin. In both proteins, the highest thermal transition is due to sugars such as lactose. The solubility study has shown that camel whey is more sensitive to pH than bovine milk whey and that heat stability is lowest near the isoelectric point of the proteins at pH 4.5. The sensitivity to pH resulted in partial denaturation and increased tendency to aggregate, which caused poor and unstable emulsion at pH 5. Both bovine and camel whey proteins have demonstrated good foaming properties; however, the magnitudes of these properties were considerably greater in bovine milk for all of the conditions studied.     

乳清蛋白改性研究进展

乳清蛋白是动物乳中的一种优质蛋白质,具有丰富的营养价值和独特的生理功能。天然乳清蛋白性质极不稳定,为使乳清蛋白得到高效利用,衍生出许多各具特色的改性方法。本文综述了利用物理方法、生物方法、化学方法及新技术改性乳清蛋白的研究进展。物理方法主要包括热处理、高压处理、微波辐照处理、超声处理、超临界二氧化碳流体处理和低温等离子体处理等;生物方法主要包括酶法水解和酶法交联处理两种;化学方法包括磷酸化、糖基化、酰化、去酰胺、酸调处理等。此外,本文总结了不同改性方法的作用机制及其对乳清蛋白性质的影响,同时展望了乳清蛋白改性技术的应用及发展趋势。     

Heat-Induced Gelation of Individual Whey Proteins A Dynamic Rheological Study

Heat-induced gelation of the bovine whey proteins [serum albumin (BSA), β-lactoglobulin (β-Lg) and α-lactalbumin (α-La)] has been studied individually and in mixture at different conditions by a dynamic rheological method. Values in the shear stiffness modulus (/G*/) appeared on heating at low protein concentration for BSA (～2%) and at intermediate concentration for β-Lg (～ 5%). α-La did not form a heat-induced gel of concentrations up to 20% (w/v). The ratio of viscous to elastic properties (loss factor) at maximum possible measuring temperature was below 0.07 for the BSA gels and 0.1–0.3 for the β-Lg gels. The temperature of gelation was highly dependent on pH. In mixture one protein could not be exchange for another without changing the gelation behavior of the mixture.     

绿茶提取物对乳清蛋白发泡特性、流变特性和热力学特性的影响

本文选用三种不同的绿茶提取物(CGT、NGT和UGT,分别来自中国、日本和肯尼亚),探讨绿茶提取物对乳清蛋白的发泡特性、流变特性和热力学特性的影响。研究结果表明:绿茶提取物可以显著提高乳清蛋白的发泡能力、发泡稳定性及胶体强度;绿茶提取物不影响乳清蛋白变性温度,但可以使其热焓值显著下降。研究结果暗示乳清蛋白与绿茶提取物中的一些主要组分发生了协同相互作用。     

Synthesis of Galactooligosaccharides in Milk and Whey: A Review

Galactooligosaccharides (GOS) are synthesized by the enzyme β‐galactosidase during the hydrolysis of lactose. In this so‐called transgalactosylation reaction the galactosyl moiety is transferred to another sugar molecule instead of water resulting in oligosaccharides of different chain lengths and glycosidic linkages. Because their structures are similar to oligosaccharides present in human breast milk, they act as prebiotics, which has been shown for infants and adults to be alike. While so far most of the research to maximize GOS yield has been carried out using buffered lactose solution as a starting material, more and more work is now conducted with dairy by‐products such as whey and whey permeate, or even milk, for direct GOS synthesis in order to develop new GOS‐enriched dairy products. This review aims to summarize the results obtained with various dairy liquids, and it rates their suitabilities to act as raw material for GOS production. Most of the studies using whey or milk have been carried out with enzymes from Aspergillus oryzae, Kluyveromyces lactis, Bacillus circulans, Streptococcus thermophilus, and several Lactobacillus species. As the initial lactose concentration (ILC) is known to be a crucial factor for high GOS yield, most of the research has been done with concentrated or supplemented milk and whey. However, a clear dependency on ILC could only be observed for the A. oryzae lactase, indicating a strong influence of milk components like minerals and proteins on the transfer activities of most enzymes.