Encapsulation and protection of resveratrol in kafirin and milk protein nanoparticles

Food proteins have been widely used as carrier materials for the encapsulation of bioactive ingredients. Combination with hydro-soluble proteins provides better properties to prolamin-based particles. Kafirin obtained from sorghum belongs to cereal prolamin proteins. In this study, kafirin nanoparticles in the absence and presence of beta-lactoglobulin (β-Lg) or casein were prepared for the encapsulation and protection of resveratrol. The particles stabilised by 2% β-Lg or 0.2% casein were the smallest in size. Encapsulation efficiency of resveratrol was between 67% and 76% in kafirin/milk protein particles and the highest in kafirin/casein particles. Encapsulation in kafirin/milk protein particles improved DPPH˙ scavenging capacity of resveratrol but decreased its ABTS˙⁺ scavenging capacity. Stability of resveratrol ranked in order kafirin/casein > kafirin/β-Lg ~ kafirin.     

改性酪蛋白标签胶的研制

介绍了由于酪素、聚乙烯醇、淀粉为主要原料制备改性酪蛋白标签胶的工艺，讨论了固含量、碱、反应温度、反应时间、交联剂、淀粉、聚乙烯醇、终点判断、耐水性、碱洗净性等因素对酪蛋白商标胶的制备与性能的影响，并对啤酒瓶贴标过程存在的问题提出了相应的解决方法。     

Dyeing of Casein Fibers with Onion Skin-Based Natural Dye Sources after Ozonation

The textile industry tries to provide different opportunities to its customers. Because of this, novel technologies in textile finishing and the use of different fibers have great importance for the textile industry. In this respect, the use of casein fiber is of interest to both manufacturers and consumers. In this study, casein-based fabrics were pretreated by means of ozone gas. The fibers themselves are clean but have low whiteness degrees. Therefore, the fabrics were bleached by means of ozone gas but limited increases in whiteness degrees were obtained. After the bleaching process, a natural dye source, namely “onion skins,” was used for the coloration of the fabrics. The dried and milled onion skin was directly added to the dyeing bath as a kind of natural dyestuff without undergoing any extraction process beforehand. In this way, it was aimed to show the usability of a vegetable waste and, at the same time, to combine ecologic processing-dyeing with casein finishing. It was observed that with the use of onion skin, the coloration of the casein fiber can be managed easily.     

Preliminary studies to determine the chaperoning properties of bovine casein and crystallin proteins at reducing beef muscle protein aggregation during heating

The ability of small heat shock proteins (sHSP) at preventing the aggregation and precipitation of unfolded and misfolded proteins because of changes in pH and temperature is widely recognised. The performance of sHSP from bovine lens extract at protecting sarcoplasmic proteins from heat induced denaturation and aggregation was compared with other chaperones including bovine serum albumin, α_s‐casein, β‐casein and a synthetic peptide based upon αA‐crystallin (AAC). Beef sarcoplasmic proteins were heated in the presence or absence of exogenous chaperone and the solubility, surface hydrophobicity and enzymatic activities of the sarcoplasmic proteins was determined. Lens extract prevented the aggregation of sarcoplasmic proteins, maintaining solubility and clarity up to 65 °C relative to 60 °C for β‐casein. By contrast, α_s‐ and β‐casein proteins protected the activity of endogenous enzymes at temperatures between 37 °C and 52 °C, unlike lens sHSP. Our findings support the addition of casein proteins as potential thermal stabilisers of meat proteins in food systems.     

Casein hydration and fat emulsification during manufacture of imitation cheese, and effects of emulsifying salts reduction

The manufacture of imitation cheese in a Farinograph was interrupted at various times, and the casein matrix formed and the free liquid were collected and analysed. During manufacture, a torque profile was generated, which showed three distinctive stages; an initial torque peak “peak-1”, followed by a trough and finally a second “peak-2”. Analyses provided quantitative and qualitative evidence that the initial manufacturing stage (peak-1) was concerned with water uptake and the formation of a hydrated casein matrix, as ∼75% of the added water was absorbed. This was followed by a fat emulsification phase (trough) and, once sufficiently emulsified, by the incorporation of the fat to form a homogeneous cheese mass, at peak-2. A similar approach showed that the effect of emulsifying salts reduction was to retard casein hydration, reflected in an increase in peak-1 torque, and led to a prolonged mixing time to sufficiently emulsify fat and allow its incorporation.     

Milk proteins differentiation and competitive adsorption during spray-drying

A non invasive method was developed to differentiate native whey proteins (NWI) and native micellar casein (NMC) at the surface of high protein milk powder. Surface analyses of the powders were performed by X-ray Photoelectron Spectroscopy (XPS). With this tool, it was impossible to differentiate casein and whey proteins by their C_1s, O_1s and N_1s signature; the atomic percentage being similar. But, minerals at the surface of these proteins were significantly different. As a consequence, a calibration curve was obtained with known mixes of both proteins and was used for their differentiation.     

Separation of casein from whey proteins by dynamic filtration

It has been proven that functional properties of milk proteins can improve the quality and nutritional value of foods. This paper investigates the separation of whey proteins from casein micelles using a Multi Shaft Disk (MSD) module and a rotating disk dynamic filtration module. The MSD module was equipped with 6 ceramic membranes of 0.2 µm pores. PVDF and Nylon membranes of 0.2 µm pores were tested in the rotating disk module. Permeate flux with the MSD module increased with TMP and rotation speed, reaching a maximum of 132 L h^− 1 m^− 2 at 1931 rpm. α-Lactalbumin (α-La) and β-Lactoglobulin (β-Lg) transmissions also increased with rotation speed, ranging from 25% at 1044 rpm to 40% at 1931 rpm . With a Nylon membrane, the rotating disk module yielded lower permeate fluxes than the MSD module, while when equipped with a PVDF membrane it provided higher permeate fluxes than the MSD, but casein micelles rejection was lower. α-La and β-Lg transmissions were higher with the rotating disk module, using Nylon and PVDF membranes, than for the MSD. From this comparison, it can be concluded that the MSD module gave the best compromise between high permeate flux, high α-La and β-Lg transmissions and high casein micelles rejection.     

Impact of enzyme preparation and degree of hydrolysis on peptide profile and nitrogen solubility of sodium caseinate hydrolysates

The solubility of casein ingredients is limited under certain pH conditions. Therefore, sodium caseinate (NaCN) was hydrolysed at laboratory scale with four enzyme preparations (Alcalase, Prolyve, FlavorPro Whey and pepsin) yielding hydrolysates having degree of hydrolysis (DH) values between 0.19 ± 0.11 and 19.25 ± 0.73%. The nitrogen solubility index (NSI) over the pH range 2.0–8.0 was affected by (i) the specificity of the enzyme preparation, (ii) the DH and (iii) the presence of unhydrolysed NaCN within the hydrolysate. The trends observed at laboratory scale (<5 L) were also seen with the semi‐pilot‐scale (300 L) hydrolysates generated with Alcalase and FlavorPro Whey. Removal of unhydrolysed NaCN from the FlavorPro Whey hydrolysate using a 5‐kDa ultrafiltration (UF) membrane increased NSI. This study has highlighted the importance of carefully selecting the proteolytic preparation along with the DH to design casein‐based ingredients with enhanced technofunctional properties.     

酪蛋白湿法糖基化改性研究

研究了酪蛋白糖基化湿法改性工艺,分析了底物配比、浓度以及pH值对酪蛋白接枝度的影响,并确定了酪蛋白-葡聚糖接枝反应的优化工艺参数。研究结果表明:pH增大有助于该反应的进行,底物的配比与浓度对反应的影响是双向的。正交分析表明,最佳反应条件为:酪蛋白浓度2mg/mL,底物配比(酪蛋白与葡聚糖的质量比)0.1,pH7.8,接枝度(DG)可达到35.10%,且褐变指数仅为0.198。乳化性能测定结果表示随着接枝度的增大,乳化性逐渐增大,当接枝度为35%时,酪蛋白的乳化性提高了约1.5倍。SDS-PAGE结果证实酪蛋白经湿法改性生成了接枝共聚物。     

Hypocholesterolaemic effect of Bifidobacterium animalis subsp. lactis (Bb12) and trypsin casein hydrolysate

Hypercholesterolaemia is one of the most important risk factors in the development of cardiovascular disease. In this study, we report the in vitro potential of Bifidobacterium animalis subsp. lactis (Bb12) cultures and bovine casein hydrolysates formed by trypsin and Bb12 culture to reduce cholesterols levels. Cholesterol levels in vitro were reduced by up to 48% after incubation with Bb12 and up to 87% after incubation with trypsin hydrolysates, whereas unhydrolysed bovine casein did not affect cholesterol levels. Individual peptide fractions, obtained from size-exclusion chromatography, from casein hydrolysates formed by trypsin after a 48 h hydrolysis, reduced cholesterol levels by 2.7–50%. The molecular masses of these fractions, containing hypocholesterolaemic peptides, were below 1200 Da, as determined by LC-MS.