Taste compound – Nanocellulose interaction assessment by fluorescence indicator displacement assay

Abstract

Interactions between taste compounds and nanofibrillar cellulose were studied. For this, a new fluorescent indicator displacement method was developed. Two fluorescent indicators, namely, Calcofluor white and Congo red, were chosen because of their specific binding to cellulose and intrinsic fluorescence. Seven taste molecules with different structures and properties were successfully measured together with NFC and ranked according to their binding constants. The most pronounced interactions were found between quinine and nanofibrillar cellulose (1.4×10 4 M-1) whereas sucrose, aspartame and glutamic acid did not bind at all. Naringin showed moderate binding while stevioside and caffeine exhibited low binding. The comparison with microcrystalline cellulose indicates that larger surface area of nanofibrillated cellulose enables stronger binding between the binder and macromolecules. The developed method can be further utilized to study interactions with different compound classes with nanocellulose materials for purposes of food, pharmaceutical and dye industries using a conventional plate reader in a highthroughput manner.

Comparing the taste‐modifying properties of nanocellulose and carboxymethyl cellulose

“…One possible explanation could be differences in the possible chemical interactions between the CMC and studied compounds. For example, fluorescence indicator method used prior to study the interactions between NFC and taste compounds (Manninen et al., 2020) could provide useful information to evaluate this possibility. It is possible that CMC may have a better antagonist capability for TAS2R bitter taste receptors than NFC, but this should be further studied.…”

“…The lower ability of nanocellulose to suppress bitterness was not expected as our hypothesis was that NFC could have a pronounced effect on the taste of bitter compound quinine. The hypothesis was based on our previous study (Manninen et al, 2020), where we showed that the binding of some compounds to nanocellulose material may be fairly significant, especially in the case of quinine, whose binding constant was measured to be 14300 M −1 . One possible explanation for the observed behavior may be that the interactions seen in fluorescence indicator studies (Manninen et al, 2020) are simply too small to have an effect on taste and thus to be noticed in sensory studies.…”

“…The hypothesis was based on our previous study (Manninen et al, 2020), where we showed that the binding of some compounds to nanocellulose material may be fairly significant, especially in the case of quinine, whose binding constant was measured to be 14300 M −1 . One possible explanation for the observed behavior may be that the interactions seen in fluorescence indicator studies (Manninen et al, 2020) are simply too small to have an effect on taste and thus to be noticed in sensory studies. Furthermore, the required concentration for bitter compounds, such as QHCl, to be recognized is lower compared to the concentration required for many sweet compounds such as sucrose (Chang et al, 2006).…”

“…In our recent study, we revealed that NFC interacts with certain taste compounds such as quinine, caffeine, stevioside, and naringin (Manninen et al., 2020). Measured binding constants varied from 70 M −1 for caffeine to 14300 M −1 for quinine.…”

96-Well Microtiter Plate Made of Paper: A Printed Chemosensor Array for Quantitative Detection of Saccharides

“…Although much effort has been devoted to chemosensors for saccharide detection, − the arrays were constructed by chemosensors that require multiple and complicated organic syntheses. To reduce the number of chemosensors and their synthetic burdens, the self-assembly approaches for chemosensor arrays with simply structured molecules would be effective. − The indicator displacement assay (IDA) , utilizing dynamic covalent bonds allows the construction of arrays with a relatively small number of simple chemosensors. , Although the utility of the IDA-based chemosensor arrays has been demonstrated using various analytes, ,,,− the IDA-based chemosensor arrays have not been applied in on-site analyses. The major cause of the limitation arises from technical issues such as the requirement of large spectroscopic equipment and fabrication costs.…”