Valorization and structural characterization of onion peel powder for the development of functional bread

Abstract

ABSTRACT Valorization of food waste has gained much popularity in current era due to the occurrence of various bioactive components in it. By-products obtained from the processing of onion are rich and dense source of bioactive components that can provide health-promoting effects when incorporated in various functional foods. Current study was conducted for the development of onion peel powder (OPP)-enriched bread. Moreover, the effect of onion waste supplementation on bread was further characterized structurally and functionally by scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy. Overall, the mean results showed the addition of OPP significantly (p <0.05) modified the overall characteristics of functional bread as well as improved its antioxidant potential. The rheological properties determined through mixographic and farinographic analysis showed that the OPP added bread results in more stable dough having 64.67%, tolerance index 134.11% softness and while 6.32 min mixing time and 54.24 ± 0.08 BU peak height. The total phenolic contents (TPC) and flavonoid content (FC) of functional breads also increased while a visible increase in DPPH activity of functional breads was observed. However, SEM revealed the OPP-enriched bread had less fine protein structure because of the presence of higher fiber content as compared control sample while the FTIR analysis revealed the presence of various functional groups in OPP bread.