Effect of drying method and process conditions on physicochemical and rheological properties of arabinoxylans extracted from corn-lime-cooking-liquor on a pilot plant scale

Abstract

Corn-lime-cooking-liquor (nejayote), which is a pollutant wastewater from the corn-tortilla-industry, contains valuable products, such as arabinoxylans (AXs) and phenolics. Recently, an innovative process that employs enzymatic and ultrafiltration processes for recovering and purifying AXs from nejayote was described, although neither the drying methods nor the physicochemical and rheological properties of the recovered AXs by this method at the pilot plant scale have been studied. Nejayote from a batch artisanal process (NBAP) and from a continuous industrial process (NCIP) were compared with a corn-bran-hydrolysate (CBH) as sources for AXs obtention. Freeze drying (FD), spray drying (SD) and solvent drying (SoD) were assessed as processes for drying purified and concentrated AXs solutions. Regardless of the process, AXs obtained from nejayote contain 3 times less (0.30 mg/g) esterified ferulic acid (EFA) than did AXs from corn bran (1.01 mg/g) and thus fail to yield elastic gels upon oxidative cross-linking. Molecular weight distribution (MwD) and dynamic viscosity data show that AXs from nejayote are shorter than AXs from corn bran. In general, the drying method had no effect on the physicochemical and rheological properties of AXs, although additional purification using ethanol precipitation and SoD, eliminated low molecular weight oligosaccharides and residual salts resulting from the neutralization of the corn-lime-cooking-liquor. Spray drying seems to be the most cost-effective unit operation for the industrial production of AXs from nejayote without affecting their physicochemical characteristics.