Natural food colorants derived from onion wastes: Application in a yoghurt product

Abstract

The valorization of onion (Allium cepa) solid wastes, a 450,000 tonnes/year waste in Europe, by a green extraction method is presented. Polyphenols of onion solid wastes were extracted using eco-friendly solvents, such as water and glycerol. The 2-hydroxypropyl-β-cyclodextrin was also used as a co-solvent for the augmentation of the extraction yield. The process has been optimized by implementing a central composite face centered design of experiments, with two replicates in the central point, taking into consideration the following independent variables: glycerol concentration, cyclodextrin concentration and temperature. The assessment of the extraction model was based on two responses: the total pigment yield and the antiradical capacity. LC-MS analysis was also employed in order to identify polyphenols and colourants of the obtained extracts. The main polyphenols found were quercetin and quercetin derivatives and the main colourant was cyanidin 3-O-glucoside. The extract was also tested as a food colourant in a yoghurt matrix. The onion leaf extract was found to be a stable natural colourant and could be utilized as an alternative ingredient to synthetic coloring agents. This article is protected by copyright. All rights reserved.

Glycerol and Glycerol-Based Deep Eutectic Mixtures as Emerging Green Solvents for Polyphenol Extraction: The Evidence So Far

“…Using oak ( Quercur robur ) acorn husks as plant matrix, polyphenol yield was optimized with 60% ( w / v ) glycerol and 13% ( w / v ) 2-hydroxypropyl β-cyclodextrin (HP-β-CD), at 80 °C [ 39 ]. Identical values for glycerol, HP-β-CD and temperature were also determined for the optimization of pigment (anthocyanin) extraction from onion solid wastes [ 41 ]. The extract thus generated was successfully used as a natural yogurt colorant.…”

Incorporation of natural colorants obtained from edible flowers in yogurts

“…Several foods, like yoghurt, are considered healthy, but they lack important components such as phenolic compounds. Therefore, the incorporation of plant extracts rich in anthocyanins in these fermented products might impart a desirable red colour, while enhancing their potential health effect (Mourtzinos et al, 2018).…”

Unraveling the Regulatory Mechanism of Color Diversity in Camellia japonica Petals by Integrative Transcriptome and Metabolome Analysis

“…Common sources of natural anthocyanins mainly include red grape marc, black carrot, purple potato, and onion (Ersus Bilek et al, 2017;Mourtzinos et al, 2018), but these cannot meet the increasing demand for natural food pigments. Therefore, finding new extraction sources of natural anthocyanins is necessary.…”