Synergistic effect of metagenome-derived starch-degrading enzymes on quality of functional bread with antioxidant activity

Starch-degrading enzymes have gained particular importance in recent decades due to their crucial role in numerous industrial applications especially, in the bakery industry. In this study, a novel thermostable pullulanase (PersiPul1) is screened from the metagenomic data for improving the quality of functional bread. The novel PersiPul1 is active over a wide range of temperature (30–80 °C) and pH (4–9) and exhibits high thermal stability, retaining 58.70% of activity at 80 °C. A cocktail of thermostable pullulanase and α-amylase (PersiPul1and PersiAmy2) is developed to be used in bread fortified with quinoa protein (Chenopodium quinoa Willd). The bread fortified with 7% quinoa protein isolate possess the highest reducing power and ABTS (73.64%) and DPPH (72.27%) radical scavenging activities. The addition of the enzyme mixture decreases the hardness and chewiness of the bread. The porosity, specific volume, and browning index of bread with pullulanase and α-amylase are higher than control. Also, sensory analysis of the functional bread reveals higher scores in the presence of enzymes. Based on the results, the novel starch-degrading enzyme cocktail is a promising alternative for improving the physical and sensory characteristics of the antioxidant bread enriched with quinoa protein isolate to be used in the bakery industry as a potential bio-additive.