Abstract: In this study, zein-based gluten-free dough (Z dough) was prepared with zein, corn starch, and Artemisia sphaerocephala Krasch gum (ASKG). Also, zein-free dough (NZ dough) was prepared with corn starch and ASKG as control. The effects of adding different amounts of lactic acid solution on farinographic properties of the doughs were compared, indicating that zein crucially affects the farinographic properties of Z dough. Among the Z dough samples, Z2 with a ratio between lactic acid solution and the total amount of raw material (L/F) of 2:50 had the longest stability time, the lowest weakening degree, and the highest farinographic index. It was found that lactic acid could cause the deamidation and hydrolysis of zein in dough, promote the transformation of α-zein diploids to haploids, and change the surface hydrophobicity and secondary structure of zein. Further, Z dough was processed into noodles to investigate the influence of lactic acid content on the cooking quality of zein-based noodles. It was found that the noodles were not easy to break and had the lowest cooking loss and good texture. In summary, an appropriate amount of lactic acid can improve the farinographic properties of zein-based gluten-free dough, increase the surface hydrophobicity of zein and the proportion of β-sheet, and improve the cooking quality of zein-based noodles.

Key words: lactic acid; zein; farinographic properties; deamidation reaction; cooking quality