Can you use citric acid instead of Vit. C as substituted for bread improver?

Yes, you can use citric acid as a substitute for vitamin C (ascorbic acid) in bread making. Both serve as dough improvers, enhancing gluten development and improving the dough's strength and elasticity. However, citric acid has a more pronounced sour flavor, so you may need to adjust the recipe accordingly to avoid altering the taste of the bread.