Thermal Degradation Kinetics of Anthocyanins Extracted from Purple Maize Flour Extract and the Effect of Heating on Selected Biological Functionality

Mioara Slavu (Ursu),Iuliana Aprodu,Ștefania Adelina Milea,Gabriela Elena Bahrim,Gabriela Râpeanu,Elena Enachi,Nicoleta Stănciuc

doi:10.3390/foods9111593

Mioara Slavu (Ursu), Iuliana Aprodu + Show 5 more

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https://doi.org/10.3390/foods9111593

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Abstract

The thermal degradation of the anthocyanins and antioxidant activity in purple maize extracts was determined between 80 and 180 °C. The anthocyanins were found to be thermostable in the temperature range of 80 to 120 °C, whereas at higher temperatures the thermal degradation of both anthocyanins and antioxidant activity followed a first-order kinetic model. The z-values started from 61.72 ± 2.28 °C for anthocyanins and 75.75 ± 2.87 °C for antioxidant activity. The conformational space of pairs of model anthocyanin molecules at 25 and 180 °C was explored through a molecular dynamics test, and results indicated the occurrence of intermolecular self-association reactions and intramolecular co-pigmentation events, which might help explaining the findings of the degradation kinetics. The relationship between thermal degradation of anthocyanins and antioxidant activity and the in vitro release was further studied. The unheated extracts showed a high stability under gastric environment, whereas after heating at 180 °C, the digestion ended quickly after 60 min. After simulated intestinal digestion, the anthocyanins were slowly decreased to a maximum of 12% for the unheated extracts, whereas an 83% decrease was found after preliminary heating at 180 °C. The thermal degradation of anthocyanins was positively correlated with the in vitro decrease of antioxidant activity.

Highlights

It has been suggested that food color is the one of the most important visual indicators of taste and flavor, as both are considered vital sensory properties of food [1]
Since accurate knowledge of the kinetic parameters is essential to predict the quality changes that occur during thermal processing of different foods, our study reports the degradation kinetic parameters of ANCs and related antioxidant activity during heating at various temperatures ranging from 80 and 180 ◦ C for different heating times
The chromatographic profile of the purple maize flour extract displayed the presence of six main compounds, namely, cyanidin-3-O-glucoside, pelargonidin-3-O-glucoside, peonidin-3-O-glucoside, cyanidin-3-O-(600 -malonylglucoside), pelargonidin3-O-(600 -malonylglucoside), and peonidin-3-O-(600 -malonylglucoside), with the two major compounds being cyanidin-3-O-glucoside and its acylated form cyanidin-3-O-(600 -malonylglucoside)

Summary

Introduction

It has been suggested that food color is the one of the most important visual indicators of taste and flavor, as both are considered vital sensory properties of food [1]. Considerable effort has been made to identify alternatives for synthetic dyes in food and beverages with natural colorants due to the public concern regarding their potential adverse effects including potential adverse behavioral and neurological effects and hyperactivity in children [2]. These studies have not established a concrete link between the intake of synthetic dyes and detrimental health effects, still a general move toward “more natural ingredients” is forcing the food processing industry to explore natural replacements for synthetic dyes [3]. These types of processing and factors might induce changes that are likely to significantly change ANCs’ concentration and bioactivity, which further affects consumer acceptance of a product

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