Ausar Salvador F, Bianco Ismael D, Castagna Leonardo F, Alasino Roxana V, Narambuena Claudio F, Leiva Ezequiel P M, Beltramo Dante M
Centro de Excelencia en Productos y Procesos de Córdoba, Agencia Córdoba Ciencia S.E., Pabellón CEPROCOR, CP 5164, Santa María de Punilla, Córdoba, Argentina.
J Agric Food Chem. 2005 Nov 16;53(23):9031-8. doi: 10.1021/jf050766o.
The cationic hydroxyethylcellulose Polyquaternium 10 (PQ10) was found to produce a dose-dependent destabilization of casein micelles from whole or skim milk without affecting the stability of most of the whey proteins. The anionic phosphate residues on caseins were not determinant in the observed interaction since the destabilization was also observed with dephosphorylated caseins to the same extent. However, the precipitation process was completely inhibited by rising NaCl concentration, indicating an important role of electrostatic interactions. Furthermore, the addition of 150 mM NaCl solubilized preformed PQ10-casein complexes, rendering a stable casein suspension without a disruption of the internal micellar structure as determined by dynamic light scattering. This casein preparation was found to contain most of the Ca2+ and only 10% of the lactose originally present in milk and remained as a stable suspension for at least 4 months at 4 degrees C. The final concentration of PQ10 determined both the size of the casein-polymer aggregates and the amount of milkfat that coprecipitates. The presence of PQ10 in the aggregates did not inhibit the activity of rennet or gastrointestinal proteases and lipases, nor did it affect the growth of several fermentative bacteria. The cationic cellulose PQ10 may cause a reversible electrostatic precipitation of casein micelles without disrupting their internal structure. The reversibility of the interaction described opens the possibility of using this cationic polysaccharide to concentrate and resuspend casein micelles from whole or skim milk in the production of new fiber-enriched lactose-reduced calcium-caseinate dairy products.
已发现阳离子羟乙基纤维素聚季铵盐10（PQ10）能使全脂或脱脂牛奶中的酪蛋白胶束产生剂量依赖性的不稳定，而不影响大多数乳清蛋白的稳定性。酪蛋白上的阴离子磷酸残基在观察到的相互作用中不是决定性因素，因为去磷酸化的酪蛋白也能观察到同等程度的不稳定。然而，氯化钠浓度升高会完全抑制沉淀过程，表明静电相互作用起重要作用。此外，添加150 mM氯化钠可溶解预先形成的PQ10 - 酪蛋白复合物，形成稳定的酪蛋白悬浮液，动态光散射测定表明其内部胶束结构未被破坏。发现这种酪蛋白制剂含有牛奶中大部分的Ca2 +，仅含有原来乳糖的10%，并在4℃下至少4个月保持稳定悬浮状态。PQ10的最终浓度决定了酪蛋白 - 聚合物聚集体的大小以及共沉淀的乳脂肪量。聚集体中PQ10的存在不抑制凝乳酶或胃肠道蛋白酶和脂肪酶的活性，也不影响几种发酵细菌的生长。阳离子纤维素PQ10可能导致酪蛋白胶束可逆的静电沉淀，而不破坏其内部结构。所描述的相互作用的可逆性为在生产新的富含纤维、低乳糖的酪蛋白钙乳制品时，使用这种阳离子多糖浓缩和重悬全脂或脱脂牛奶中的酪蛋白胶束提供了可能性。
