Use of Time-Resolved Fluorescence to Monitor Bioactive Compounds in Plant Based Foodstuffs

Abstract

The study of compounds that exhibit antioxidant activity has recently received much interest in the food industry because of their potential health benefits. Most of these compounds are plant based, such as polyphenolics and carotenoids, and there is a need to monitor them from the field through processing and into the body. Ideally, a monitoring technique should be non-invasive with the potential for remote capabilities. The application of the phenomenon of fluorescence has proved to be well suited, as many plant associated compounds exhibit fluorescence. The photophysical behaviour of fluorescent molecules is also highly dependent on their microenvironment, making them suitable probes to monitor changes in pH, viscosity and polarity, for example. Time-resolved fluorescence techniques have recently come to the fore, as they offer the ability to obtain more information, coupled with the fact that the fluorescence lifetime is an absolute measure, while steady state just provides relative and average information. In this work, we will present illustrative time-resolved measurements, rather than a comprehensive review, to show the potential of time-resolved fluorescence applied to the study of bioactive substances. The aim is to help assess if any changes occur in their form, going from extraction via storage and cooking to the interaction with serum albumin, a principal blood transport protein.

Binding of Clitoria ternatea L. flower extract with α-amylase simultaneously monitored at two wavelengths using a photon streaming time-resolved fluorescence approach

“…We have previously used this to investigate food related bioactive compounds [26]. In order to follow the binding kinetics a "histogram streaming" approach (also referred to as "kinetic TCSPC") was employed.…”

“…This involves the seamless collection of decay histograms, with acquisition times as short as 1 ms. This approach was used to monitor the binding of curcuminoids to serum albumin [24,26] and allowed the application of the fluorescence lifetime to monitor the interaction process. However, this approach does not have the capability to post process on shorter timescales than selected in the initial measurement conditions and is limited to one detection channel.…”

Light Emission in Betalains: From Fluorescent Flowers to Biotechnological Applications

“…Fluorescence of betaxanthins has also been applied to the determination of the pigments as a function of storage conditions in foods [74]. Time-resolved fluorescence has been applied to the study of raw beet roots that have been stored under vacuum and refrigerated for up to 41 days.…”

“…Time-resolved fluorescence has been applied to the study of raw beet roots that have been stored under vacuum and refrigerated for up to 41 days. The proof of concept, based on fluorescence decay, proposes the possibility of using this noninvasive technique to study the evolution of betalains in foods [74,75]. The addition of betaxanthins as a dye to transform dim objects into fluorescent is also possible, as has been demonstrated for wool [76].…”

Introduction to Special Issue on “Fluorescence-Based Sensing Technologies”

“…Away from the medical applications of biosensors is the extremely important area of sensing within the food industry where there is a need for the development of sensors for foodstuffs. This review presents how time-resolved fluorescence measurements can be applied to monitoring bioactive compounds in plant-based food stuffs [ 4 ]. The review describes time-resolved fluorescence techniques which are applicable to many biosensing applications and as such provides a useful reference.…”