Scleroglucan compatibility with thickeners, alcohols and polyalcohols and downstream processing implications

• Published in: Carbohydrate polymers 2013-02, Vol.92 (2), p.1107-1115
• Main Authors: Viñarta, Silvana C., Yossen, Mariana M., Vega, Jorge R., Figueroa, Lucía I.C., Fariña, Julia I.
• Format: Article
• Language: English
• Subjects: 1-propanol; Alcohols; Applied sciences; Athelia rolfsii; Biological and medical sciences; carboxymethylcellulose; Compatibility; corn starch; Downstream processing; ethanol; ethylene glycol; Exact sciences and technology; exopolysaccharides; Food additives; Food Additives - chemistry; Food Handling; Food industries; Fundamental and applied biological sciences. Psychology; gelatin; General aspects; Glucans - chemistry; Glycols - chemistry; gum arabic; isopropyl alcohol; mannitol; methanol; Molecular Weight; Natural polymers; pectins; Physicochemistry of polymers; polyethylene glycol; rheological properties; Rheology; Scleroglucan; Sclerotium rolfsii; sensory properties; sorbitol; Starch and polysaccharides; Sugar Alcohols - chemistry; synergism; Thickeners; water solubility; xanthan gum; xylitol
• ISSN: 0144-8617; 1879-1344
• DOI: 10.1016/j.carbpol.2012.10.065

► Sclerotium rolfsii ATCC 201126 EPSs were compatible and synergistic with commercial hydrocolloids. ► Mixtures with polyethylene glycol (PEG) or lower alcohols induced EPSs precipitation. ► PEG-based scleroglucan downstream processing would be unsuitable. ► Purity, solubility, rheological properties and appearance were optimal for isopropanol-purified EPSs. ► Isopropanol-downstream processing was appropriate for obtaining refined-grade scleroglucan. 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 (Mw, 2.66×106g/mol) and a radius of gyration (Rw, 245nm) slightly lower than ethanol-purified EPSs, isopropanol downstream processing showed to be a proper methodology for obtaining a refined-grade scleroglucan.