Effect of nixtamalization treatment of three varieties of grain sorghum on the reduction of total phenolics and their subsequent enzymatic hydrolysis

Abstract

This work assessed the effect of lime treatment (nixtamalization) on the reduction of tannins in grain sorghum and on the subsequent enzymatic hydrolysis of the limetreated flours. A split-plot experimental design for the lime treatment and a factorial experimental design, with variety of sorghum and lime concentration as factors, were used. Sorghum flours were prepared by cooking sorghum grains (low, medium, and high tannins) in lime solutions (0.0%, 0.3%, and 0.5%) for 35 min at 87°C, steeping for 8 hr, washing, drying, and sieving. Lime treatment reduced the tannins content by 82%, 67%, and 53% with 0.3% lime and by 79%, 68%, and 49% with 0.5% lime treatments for high, medium, and low tannins varieties. Hydrolysis with α-amylase and amyloglucosidase showed that sorghum variety, lime concentration, and their interaction were highly significant in the production of fermentable sugars (p < 0.001). Conversion efficiency of starch into fermentable sugars increased with rising concentrations of lime. Practical applicationsThe present study demonstrated that lime-pretreatment (nixtamalization) of sorghum grain effectively reduce the polyphenols content in grain sorghum, particularly condensed tannins. Subsequently, the reduction of polyphenols improves the conversion of starch into fermentable sugars, which is highly beneficial in industrial fermentations.

Propiedades nutricionales, funcionales y bioactivas de alimentos a base de sorgo: Avances y oportunidades para su aprovechamiento integral

“…Este proceso requiere una cocción del grano en una solución de Ca(OH)2 (10kg por cada 2 kg de harina de sorgo), durante 20 a 45 minutos, dejarlo reposar por 8 a 24 horas y posteriormente lavarlo para eliminar el álcali y el pericarpio residuales. La nixtamalización produce cambios en las propiedades estructurales de los productos de sorgo (harina), aumentando la bioaccesibilidad de las proteínas, mejorando así su valor nutritivo (Gaytán-Martínez et al, 2017;Díaz et al, 2019;Cabrera-Ramírez et al, 2020). Sin embargo, para poder desarrollar un alimento a base de sorgo es necesario conocer sus propiedades estructurales y funcionales (Adebo, 2020;Cayres et al, 2020).…”

Impact of germination pre-treatments on buckwheat and Quinoa: Mitigation of anti-nutrient content and enhancement of antioxidant properties

“… Beta et al (2000) used sodium hydroxide (NaOH) as an alkali pre-treatment to reduce tannin content in sorghum and increase the malt quality. Besides NaOH, sodium bicarbonate (NaHCO 3 ) and lime (Ca(OH) 2 ) solutions can be used in various alkaline treatments to evaluate changes in phenolic content and antioxidant capacity of sorghum ( Díaz González et al, 2019 , Gaytán-Martínez et al, 2017 ). However, the effects of ultrasound and alkali pre-treatment on enhancing antioxidant properties and mitigating tannin and phytic acid content in germinated buckwheat and quinoa have not been studied.…”