Gelation of Arabinoxylans from Maize Wastewater — Effect of Alkaline Hydrolysis Conditions on the Gel Rheology and Microstructure

Abstract

The purpose of this research was to extract arabinoxylans (AX) from maize wastewater generated under different maize nixtamalization conditions and to investigate the polysaccharide gelling capability, as well as the rheological and microstructural characteristics of the gels formed. The nixtamalization conditions were 1.5 hours of cooking and 24 hours of alkaline hydrolysis (AX1) or 30 minutes cooking and 4 hours of alkaline hydrolysis (AX2). AX1 and AX2 presented yield values of 0.9% and 0.5% (w/v), respectively. Both AX samples presented similar molecular identity (Fourier Transform Infra-Red) and molecular weight distribution but different ferulic acid (FA) content. AX1 and AX2 presented gelling capability under laccase exposure. The kinetics of gelation of both AX samples was rheologically monitored by small amplitude oscillatory shear. The gelation profiles followed a characteristic kinetics with an initial increase in the storage modulus (G') and loss modulus (G") followed by a plateau region for both gels. AX1 presented higher G' than AX2. In scanning electron microscopy (SEM) images, both gels present an irregular honeycomb microstructure. The lower FA content in AX2 form gels presenting minor elasticity values and a more fragmented microstructure. These results indicate that nixtamalization process conditions can modify the characteristics of AX gels.

Electrospray‐assisted fabrication of core‐shell arabinoxylan gel particles for insulin and probiotics entrapment

“…This high arabinose content increases the molecule hydrophilic characteristic and therefore the solubility in water . The FA content in MBAX was 0.025 ± 0.001 (µg/mg polysaccharide), which is lower than the value reported for another MBAX extract but higher than FA content found in MWAX in the present study and in previous investigations . MWAX and MBAX have different physicochemical characteristics and gelling capacity (Tables and Figure ).…”

“…Chemical products as acridine orange, rhodamine B isothiocyanate, laccase (benzenediol:oxygen oxidoreductase, E.C.1.10.3.2) from Trametes versicolor and recombinant human insulin were acquired from Sigma Co. (St. Louis, Missouri). MWAX was extracted and characterized as previously described . MBAX were extracted according to Carvajal‐Millan et al .…”

Maize Processing Waste Water Upcycling in Mexico: Recovery of Arabinoxylans for Probiotic Encapsulation

“…Niño-Medina et al [2] reported a moderately branched structure (A/X = 0.65) for MWAX and a maximal concentration of just 8% (w/v) of MWAX in water. Small amounts of glucose, galactose, protein, and minerals (ashes) were also detected in MWAX, similarly to previous reports on other maize AX [2][3][4]. The FA content in MWAX was 0.012 ± 0.001 (µg/mg polysaccharide), which is smaller than the value reported for other MWAX (0.23 µg/mg polysaccharide).…”

“…The waste water generated from this maize processing is called "Nejayote" which is highly alkaline, with high chemical and biological oxygen demands, and is considered an environmental pollutant. A typical maize nixtamalization facility processing 50 kg of maize every day uses over 75 L of water per day and generates nearly the equivalent amount of equivalent amount of alkaline waste water in 24 h [3]. Thus, alternatives of maize alkaline waste water utilization in Mexico are needed.…”

“…During the nixtamalization process, maize bran is removed from the kernel, and some of the cell wall components such as arabinoxylans are partially solubilized in Nejayote. In fact, Nejayote has been previously reported as a source of gelling arabinoxylans [2][3][4].…”