PROIMI-CONICET, Av. Belgrano y Caseros, T4001MVB Tucumán, Argentina.
Carbohydr Polym. 2013 Feb 15;92(2):1107-15. doi: 10.1016/j.carbpol.2012.10.065. Epub 2012 Nov 1.
Thickening capacity and compatibility of scleroglucan with commercial thickeners (corn starch, gum arabic, carboxymethylcellulose, gelatin, xanthan and pectin), glycols (ethylene glycol and polyethylene glycol), alcohols (methanol, ethanol, 1-propanol and isopropanol) and polyalcohols (sorbitol, xylitol and mannitol) was explored. Exopolysaccharides (EPSs) from Sclerotium rolfsii ATCC 201126 and a commercial scleroglucan were compared. Compatibility and synergism were evaluated taking into account rheology, pH and sensory properties of different thickener/scleroglucan mixtures in comparison with pure solutions. S. rolfsii ATCC 201126 EPSs induced or increased pseudoplastic behaviour with a better performance than commercial scleroglucan, showing compatibility and synergy particularly with corn starch, xanthan, pectin and carboxymethylcellulose. Compatibility and a slight synergistic behaviour were also observed with 30% (w/v) ethylene glycol whereas mixtures with polyethylene glycol (PEG) precipitated. Scleroglucan was compatible with polyalcohols, whilst lower alcohols led to scleroglucan precipitation at 20% (v/v) and above. PEG-based scleroglucan downstream processing was compared to the usual alcohol precipitation. Downstream processed EPSi (with isopropanol) and EPS-p (with PEG) were evaluated on their yield, purity, rheological properties and visual aspect pointing to alcohol downstream processing as the best methodology, whilst PEG recovery would be unsuitable. The highest purified EPSi attained a recovery yield of ~23%, similar to ethanol purification, with a high degree of purity (88%, w/w vs. EPS-p, 8%, w/w) and exhibited optimal rheological properties, water solubility and appearance. With a narrower molecular weight distribution (M(w), 2.66×10(6) g/mol) and a radius of gyration (R(w), 245 nm) slightly lower than ethanol-purified EPSs, isopropanol downstream processing showed to be a proper methodology for obtaining a refined-grade scleroglucan.
研究了葡聚糖胶与商业增稠剂(玉米淀粉、阿拉伯胶、羧甲基纤维素、明胶、黄原胶和果胶)、二醇(乙二醇和聚乙二醇)、醇(甲醇、乙醇、1-丙醇和异丙醇)和多元醇(山梨糖醇、木糖醇和甘露醇)的增稠能力和相容性。比较了来自 Sclerotium rolfsii ATCC 201126 的胞外多糖(EPS)和一种商业葡聚糖胶。考虑到不同增稠剂/葡聚糖混合物与纯溶液相比的流变学、pH 值和感官特性,评估了相容性和协同作用。S. rolfsii ATCC 201126 EPS 诱导或增加了假塑性行为,性能优于商业葡聚糖胶,与玉米淀粉、黄原胶、果胶和羧甲基纤维素表现出相容性和协同作用。在 30%(w/v)乙二醇中也观察到了相容性和轻微的协同作用,而与聚乙二醇(PEG)的混合物则沉淀。葡聚糖胶与多元醇相容,而在 20%(v/v)及以上的低醇中则导致葡聚糖胶沉淀。比较了基于 PEG 的葡聚糖胶下游处理与常用的醇沉淀。对下游处理的 EPSi(异丙醇)和 EPS-p(PEG)进行了产率、纯度、流变性能和外观评价,表明醇类下游处理是最佳方法,而 PEG 回收则不合适。纯度最高的 EPSi 回收率约为 23%,与乙醇纯化相似,纯度较高(88%,w/w 与 EPS-p,8%,w/w),表现出最佳的流变性能、水溶性和外观。具有更窄的分子量分布(M(w),2.66×10(6) g/mol)和较低的回转半径(R(w),245 nm),低于乙醇纯化的 EPSs,异丙醇下游处理显示是一种获得精制级葡聚糖胶的合适方法。