Investigation of the effects of psyllium powder addition on the quality of fresh and frozen gluten-free bread

Abstract

The interest in gluten-free (GF) products has been growing since both the increase in prevalence of celiac disease and the preferences of GF diet. In this study, the contribution of psyllium powder (PP) to gluten-free (GF) bread quality, dough rheology and volatile compounds (VCs) profile was investigated throughout the frozen storage period of GF dough (-30 °C for 0, 7, 15, and 30 days). GF doughs containing 7.5% PP (PSY1) and 15% PP (PSY2) had lower tanδ value than GF control dough (p<0.05) according to the results obtained from fundamental rheological analysis. Frozen storage caused no effect on the tanδ value of PSY1 and PSY2 (p ≥ 0.05). PP addition increased the specific volume (SV) of GF breads (p<0.05). No significant effect of frozen storage on SV was shown for PSY2 while SV values of GF control bread (GFB) and PSY1 decreased (p<0.05). Lower crumb hardness was shown for PSY1 and PSY2 on day 0. Significant effect of frozen storage on crumb hardness was observed for PSY1 on day 30 while harder crumb structure was shown for GFB throughout the frozen storage (p<0.05). Psyllium addition led to a significant reduction in both L* value of crust and crumb color (p<0.05). In the VCs analysis performed by HS/GC-MS, ethanol and 1-butanol, 3-methyl from alcohol group, butanal, 3-methyl- and hexanal from aldehydes were common for GFB and GF breads containing psyllium. 1-butanol, 3-methyl-, butanal, 3-methyl- and hexanal were the VCs of PSY1 and they were also shown after frozen storage. This study suggested that quality deterioration due to frozen storage was less in gluten-free breads containing psyllium.