Abstract
Corn fibre, a co-product of the starch industry, is rich in compounds with high added value, such as ferulic acid and arabinoxylans, which are released during alkaline extraction. This work aims to optimise an efficient separation method for the recovery of these two compounds from a corn fibre alkaline extract, allowing an efficient valorisation of this co-product. Ultrafiltration was selected as separation method, due to its potential to fractionate these compounds. In order to minimise the loss of membrane permeance, due to mass transfer limitations caused by the high arabinoxylan viscosity, the impact of relevant ultrafiltration operating parameters (membrane molecular weight cut-off, fluid dynamics conditions, transmembrane pressure, and operating temperature) were evaluated. A Nadir UP 150 membrane was found to be an adequate choice, allowing for an efficient separation of ferulic acid from arabinoxylans, with null rejection of ferulic acid, a high estimated rejection of arabinoxylans 98.0% ± 1.7%, and the highest permeance of all tested membranes. A response surface methodology (RSM) was used to infer the effect of ultrafiltration conditions (crossflow velocity, transmembrane pressure and operating temperature) on the rejection of ferulic acid, retention of arabinoxylans (assessed through apparent viscosity of the retentate stream), and permeance. Through mathematical modelling it was possible to determine that the best conditions are the highest operating temperature and initial crossflow velocity tested (66 °C and 1.06 m.s−1, respectively), and the lowest transmembrane pressure tested (0.7 bar).
Highlights
The most abundant low-value co-product of the corn wet milling process is corn fibre [1], which contains a significant fraction of valuable phenolic compounds, mainly ferulic acid
With the aim of optimising the conditions needed to fractionate an alkaline extract from corn fibre, we assessed the most relevant operating parameters of an ultrafiltration process—membrane molecular weight cut-off, operating temperature, crossflow velocity, and transmembrane pressure
It was found that the ultrafiltration conditions do not influence the global rejection of ferulic acid
Summary
The most abundant low-value co-product (used for animal feed) of the corn wet milling process is corn fibre [1], which contains a significant fraction of valuable phenolic compounds, mainly ferulic acid. Ferulic acid presents several recognised benefits, namely antioxidant, anti-inflammatory, antiatherogenic, antidiabetic, antiaging, neuroprotective, radioprotective, hepatoprotective, and antiproliferative properties [6,7,8], which make this compound widely used in the food, cosmetics, and pharmaceutical industries It can be used as a crosslinking agent for the preparation of films [9,10] and as precursor of bio-vanillin production [11,12]. Arabinoxylans, designated as corn fibre gum, are valuable non-starch cereal polysaccharides [13], with many recognized health benefits, such as a prebiotic, for the control of diabetes, immunomodulatory activity, and a cholesterol lowering effect [14,15,16] They have a functional application in edible film forming [17,18]
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