Co-pigmentation of strawberry anthocyanins with phenolic compounds from rooibos

Sevcan Erşan; Madlen Müller; Luise Reuter; Reinhold Carle; Judith Müller-Maatsch

doi:10.1016/j.fochms.2022.100097

Co-pigmentation of strawberry anthocyanins with phenolic compounds from rooibos

Food Chem (Oxf). 2022 Mar 12:4:100097. doi: 10.1016/j.fochms.2022.100097. eCollection 2022 Jul 30.

Authors

Sevcan Erşan¹, Madlen Müller¹, Luise Reuter¹, Reinhold Carle^{1

2}, Judith Müller-Maatsch¹

Affiliations

¹ University of Hohenheim, Institute of Food Science and Biotechnology, Chair of Plant Foodstuff Technology and Analysis, Garbenstrasse 25, 70599 Stuttgart, Germany.
² King Abdulaziz University, Faculty of Science, Biological Science Department, P. O. Box 80257, Jeddah 21589, Saudi Arabia.

Abstract

Anthocyanin-rich strawberry model solutions were co-pigmented with rooibos phenolics to enhance color and heat stability. The addition of green and fermented rooibos extracts at pigment-to-co-pigment molar ratios of 1:10, 1:50, and 1:100 pelargonidin-3-glucoside equivalents: orientin equivalents induced hyper- and bathochromic shifts at room temperature and during thermal processing at 80 °C for an hour. Co-pigmentation effects on hyperchromic shift were up to 96%, and bathochromic shift reached 19 nm when adding flavonoid-rich fractions of green rooibos phenolics. Following the co-pigmentation tests with rooibos extracts, selected pure phenolic co-pigments were tested for their monomeric contribution to the observed co-pigmentation effects. Orientin was identified as a potent co-pigment for pelargonidin-3-glucoside, showing stronger co-pigmentation effects than that of its aglycon luteolin. Additionally, orientin had the most pronounced bathochromic shift in heat-treated solutions. Rooibos extracts, particularly flavonoid-rich fractions composed of luteolin, apigenin, and quercetin glycosides, are suggested as color enhancers and stabilizers for strawberry products.

Keywords: AU, absorption unit; Aspalathus linearis (Burm.f.) R. Dahlgren; Co-pigmentation; Color enhancer; DAD, diode array detector; ESI, electrospray ionisation; Fragaria x ananassa Duch.; Gallic acid; HPLC, high-performance liquid chromatography; Heat stability; Luteolin; MSn, multiple-stage mass spectrometry; OE, orientin eqivalents; Orientin; PE, pelargonidin-3-glucoside equivalents; Penta-galloyl-glucose; RT, room temperature; SPE, solid-phase extraction; Δλmax, bathochromic shifts of the absorbance maximum.