Impact of acid and alkali treatments on the nutritional, functional, and structural properties of hull-less barley flour.

Abstract

Barley is an underutilized crop with considerable potential for enhancing food security and sustainability. Hull-less barley is a nutrient-dense cereal grain rich in β-glucan and dietary fiber; however, its broader application in food systems is constrained by the presence of antinutritional factors and certain functional limitations that affect processing and bioavailability. This study investigated the effects of acid (1% HCl) and alkali (1% NaOH) treatments on two hull-less barley varieties (PL 891 and BHS 352), with emphasis on nutritional composition, antinutrient reduction, functional behavior, thermal transitions, and microstructural attributes. Both treatments improved dietary fiber and β-glucan content, with PL 891 increasing from 15.59% to 19.98% and 3.52% to 5.05%, respectively. Alkali treatment proved more effective in reducing antinutritional factors, such as tannins, decreased by 59%, phytic acid by 21%, and trypsin inhibitor activity by 42%, thus enhancing mineral bioavailability. While antioxidant activity and total phenolic content improved more prominently in acid-treated samples, alkali treatment led to superior functional attributes. Thermal analysis showed elevated gelatinization temperatures and higher enthalpy, reflecting enhanced thermal stability. Peak viscosity values reached 3450 cP in alkali-treated BHS 352, indicating improved gelling and hydration potential. Scanning electron microscope and Fourier transform infrared spectrometer analyses confirmed granule disruption, protein unfolding, and hydrogen bond rearrangement, contributing to better water interaction and digestibility. These findings highlight the potential of chemically treated hull-less barley flours as functional, health-promoting ingredients in value-added food applications, advancing sustainable nutrition in line with global development goals.