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1.
Ida-Marie Andersson Björn Bergenståhl Marcela Alexander Marie Paulsson Maria Glantz 《International Journal of Food Science & Technology》2021,56(1):480-492
During whey powder production, the feed is subjected to several heat treatments which can cause lactosylation of proteins. In this study, lactosylation of whey proteins was evaluated in spray-dried powders before and after storage by varying the native protein fraction as well as the serum protein/lactose ratio in the powders. The lactosylation of native α-lactalbumin and β-lactoglobulin in the powders before storage was not affected to a large extent by the protein denaturation or if the feed had been heat treated in a high or low lactose environment. After storage (relative humidity of 23.5%, 30 °C, 25 days), the kinetic of lactosylation tended to increase with increasing native protein fraction and bulk protein content in the powders. An explanation could be that proteins dissolved in the lactose glassy structure might have a lower reactivity, while proteins present in the protein glassy structure with dissolved lactose may display higher lactosylation reactivity. 相似文献
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本文介绍了以各种中药材为主要原料 ,配以茶叶为辅料 ,运用先进的处理方法制备降脂减肥果茶的生产工艺、质量标准 ,并对确定生产工艺的几个主要问题进行了探讨 相似文献
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This study was carried out to determine the physical, chemical, microbiological and organoleptic properties of koumiss made from bovine milk. The bovine milk was modified according to the composition of mares’ milk using ultrafiltration, microfiltration and nanofiltration. Koumiss made from modified bovine milk and mares’ milk were compared. In order to assess options for a consistent fermentation, a starter culture, instead of the prevailing spontaneous flora in traditional manufacture of koumiss, was used. Key compositional factors modified were the contents of dry matter, mineral, protein and lactose and the casein-to-whey protein ratio. Koumiss made from modified bovine milk and by starter cultures was found to be very similar to koumiss from mares’ milk in terms of pH, titratable acidity, alcohol, proteolytic activity, apparent viscosity, and microbiological composition, when assessed both in the freshly made product and that after 15 days storage at 4°C. 相似文献
6.
Neal E. Craft Katherine S. Epler Therese A. Butler Willie E. May Regina G. Ziegler 《Journal of research of the National Institute of Standards and Technology》1993,98(3):355-359
Aliquots of serum collected in a large case-control study of cervical cancer were stored at −70°C for up to 4 years during implementation of the study. When 500 μL serum aliquots were thawed in preparation for carotenoid and vitamin A assays, volumes were noticeably variable and fell below 500 μL in the majority of the samples. We were concerned about evaporation/sublimation during storage of the samples because loss of water would concentrate the analytes of interest. We evaluated the use of density and sodium ion concentration measurements to confirm its occurrence. We found that serum density was an unreliable indicator of extent of volume loss since the anticipated increases in density due to evaporation were of the same magnitude as inter-individual variation in serum density. In contrast, Na+ concentration is tightly regulated and would rise if water had been lost from the samples. In a representative sample of serum aliquots from the case-control study, 24 of 25 vials contained less than 500 μL of serum. The mean sodium ion concentration (138.1 ± 3.6 mmol/L) was within the normal range for human serum of 136–145 mmol/L, and no correlation was observed between serum volume and Na+ concentration. These results strongly suggest that the observed low volumes were not due to evaporative losses. Instead, the variably low volumes of serum aliquots were probably due to pipetting errors in the initial aliquotting resulting from the use of air-displacement pipettes. 相似文献
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应用新的特异性θ诊断血清和传统商品血清与434株伤寒沙门氏菌地方株作玻片凝集平行试验,两者诊断符合率为100%。θ血清与0.1%酚琼脂斜面上的所有伤寒沙门氏菌呈迅速清晰的阳性凝集反应。鉴于θ血清与大多数D群沙门氏菌不凝集,因此,大大提高诊断的正确性。 相似文献
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采用人胎盘血为原料,利用Sephadex G-200,DEAE-Sephadex A-50层析,Sepharose 4B反相免疫亲和层析技术,获得妊娠相关血浆蛋白A(PAPP-A)纯品,经8.0%聚丙烯酰胺凝胶电泳、免疫电泳、双向免疫扩散证明,所提取的PAPP-A纯品为单一成分。免疫家兔获得抗血清,其效价在1:16以上。 相似文献
9.
蛋白质在超滤过程中的膜污染和膜清洗 总被引:9,自引:0,他引:9
本文选用四种不同的膜清洗剂对牛血清蛋白溶液超滤后污染的三种超滤膜进行研究,结果表明:在蛋白质的等电点取得在不同PH值下蛋白质对膜污染的最佳清洗效果,清洗效率与蛋白质的所荷电荷有关。采用适宜的清洗过程将会延长膜使用寿命和增强超滤膜性能。 相似文献
10.
Citrate-stabilized CdSe/CdS quantum dots as fluorescence probe for protein determination 总被引:1,自引:1,他引:0
A rapid, ultrasensitive and convenient fluorescence measurement technology based on the enhancement of the fluorescence intensity
resulting from the interaction of functionalized CdSe/CdS quantum dots (QDs) with bovine serum albumin (BSA) was proposed.
The citrate-stabilized CdSe/CdS (QDs) were synthesized by using Se powder and Na2S as precursors instead of any pyrophoric organometallic precursors. The modified CdSe/CdS QDs are brighter and more stable
against photobleaching in comparison with organic fluorophores. At pH 7.0, the fluorescence signal of CdSe/CdS is enhanced
by increasing the concentration of BSA in the range of 0.1–10 μg/mL, and the low detection limit is 0.06 μg/mL. A linear relationship
between the enhanced fluorescence peak intensity (ΔF) and BSA concentration (c) is established using equation ΔF=50.7c+16.4 (R=0.996 36). Results of determination for BSA in three synthetic samples are identical with the true values, and the recovery
(98.9%–102.4%) and relative standard deviation (RSD, 1.8%–2.5%) are satisfactory. 相似文献