Isolation, Optimization, and Structural Characterization of Melanoidins Obtained from Bread Industry By-products as Bioactive Compounds

Abstract

Melanoidins are bioactive compounds that have an impact on food properties and have effects on health. Due to the high content of melanoidins in bread crust, it can be used as a source of these compounds. Their recovery from bakery by-products can reduce environmental pollution and provide added value. The aim of this study was to evaluate the efficiency of ultrafiltration to obtain melanoidin extracts from crust of common and soft bread obtained as industrial by-products and to compare their structure and antioxidant and chelating activity. The high-molecular-weight (HMW > 10 kDa) melanoidin extract was obtained by ultrafiltration conditions optimized to ensure minimum fouling and to obtain a melanoidin extract with a minimum content of low-molecular-weight (LMW) compounds that could be toxic. FTIR spectroscopy revealed significant similarities between both melanoidin samples, but differences were observed with their LMW fractions. Melanoidins, which are melanoproteins, exhibited higher carbohydrate levels in the extract from soft bread, whereas the extract from common bread contained more proteins and polyphenolic compounds. Despite having a lower browning index and K420, the melanoidin from soft bread exhibited higher antiradical and chelating properties. In conclusion, this study provides our understanding of the structural and functional aspects of bread melanoidins.