Monitoring the Interaction between Thermally Induced Whey Protein and Anthocyanin by Fluorescence Quenching Spectroscopy.

Shuai Ren,M Monica Giusti

doi:10.3390/foods10020310

Abstract

The color stability of anthocyanins was shown to improve with addition of whey proteins (WP). The goal of this study was to investigate the binding mechanisms of purple corn, grape and black carrot anthocyanin extracts to native and preheated WP (40–80 °C, 3.6 μM) at a pH of 3 using fluorescence quenching spectroscopy. The fluorescence spectra were collected with an excitation wavelength of 280 nm at 25 °C, 35 °C and 45 °C. The quenching data were analyzed by using the Stern–Volmer equation. The fluorescence intensity of WP decreased (up to 73%) and its λmax increased (by ~5 nm) with increasing anthocyanin concentration (0–100 μM). The quenching data showed that the interaction between anthocyanin extracts and WP was a static quenching process. Thermodynamic analysis showed their binding was mainly through hydrophobic interactions. Their binding affinity was higher for preheated WP than native WP and decreased gradually with increasing preheating temperature. Black carrot anthocyanin extract had the lowest binding affinity with WP, likely due to the larger molecular structure. These results help better understand the protection mechanism of native and preheated WP on anthocyanin color stability, expanding the application of anthocyanins as food colorants that better withstand processing and storage.

Highlights

Anthocyanins (ACN), as natural food colorants, are widely studied and used frequently in the food industry to provide or improve color in food products like jams, canned foods, yogurt, juices or confectioneries, because of their bright and attractive colors from red to purple, nontoxicity and water solubility [1]
Their compositions were analyzed by ultra-high-performance liquid chromatography
All peaks were glycosylated by one glucose and the main ACN were Cy-3-glucoside, Pe-3-glucoside (a2n.9d0%th)e.irAmlal lpoenaicksacwidearecyglalyticoonsycloautendterbpyarotns.e glucose and the main ACN were Cy-3glucoAsiddde,itPioen-3o-gflAucCoNsid-reicahnedxtthraecirtsmtoalWonPicsaocliudtiaocnyslarteiosunltceodunintecrhpaanrtgse. s to the whey proteins (WP) fluoresceAndcedistipoenctorfa,AbCoNth-riicnhfeluxtorraecstcsetnocWe iPntseonlusittiyonasnrdesλumltaexd

Summary

Introduction

Anthocyanins (ACN), as natural food colorants, are widely studied and used frequently in the food industry to provide or improve color in food products like jams, canned foods, yogurt, juices or confectioneries, because of their bright and attractive colors from red to purple, nontoxicity and water solubility [1]. Studies showed that ACN were effective antioxidants and might aid in the prevention of cardiovascular diseases, inflammation, certain cancers, diabetes and obesity [2,3] Despite their important biological effects, ACN have limited chemical stability due to their sensitivity to different factors, such as processing conditions and storage, including other food matrices, pH, temperature, light, oxygen, metal ions, sulfur dioxide, vitamin C and enzymes [4,5]. Their limited stability constrains their commercial application as colorants in processed foods, especially those thermally processed. It is meaningful and challengeable to find an effective way to reduce ACN loss during food processing and storage

Objectives

Methods

Results

Conclusion