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A fast and effective analytical method to quantify the emulsifying activity: design and validation
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Abstract(s)
ABSTRACT: Biosurfactants (BS) and bioemulsifiers (BE) are amphiphilic molecules that are produced by a wide range of microorganisms. According to Willumsen and Karlson, BS/BE are both surface active biomolecules, but while the surfactants play the role of surface tension reduction, emulsifiers are involved in formation and stabilization of emulsions. However, some biomolecules possess both surfactant and emulsifying properties, which contributes to their unique features, including high biodegradability, low toxicity, effectiveness at extremes of temperature, pH and salinity, and special biological activities (e.g., antimicrobial, antiviral,
anticancer, etc). These attributes make them an alternative to their chemical counterparts and allows them
to have key roles in several fields. In fact, the chemical composition of BS and BE is different, and this may contribute to their specific roles in nature and biotechnological applications; however, both BS/BE have recognized emulsifying properties, which are the focus of this study. The idea of quantifying the emulsifying activity rather than quantifying the emulsifiers and/or surfactants themselves has been studied before. The concept that stands out is the emulsification index (E24: % emulsification after 24 h) proposed by Cooper and Goldenberg [4], which is still applied, and some of its adaptations such as the one proposed by Trebbau de Acevedo and McInerney. These authors have defined one unit of emulsifying activity as the amount of emulsifier that results in an emulsification (E24) of 20%. Although theoretically simple, these approaches require considerable sample volume, have a long wait (24 h) and are lengthy. Moreover, they can be subjective, since two substances might induce complete emulsion at 24 h, with one resulting in a much denser emulsion. This may indicate more BS/BE activity; however, it is not easily comparable, or demonstratable. Furthermore, due to nature of emulsions and the factors that influence them, small differences in test conditions, such as shape or size of the tubes, or nature of the hydrophobic layer, can generate drastic differences, which hinders reproducibility between authors.
Description
Keywords
Biosurfactants Bioemulsifiers Analytical method Emulsifying activity Emulsification unit
Citation
Alves L.; J. Tavares, Tiago P. Silva, S.M. Paixão (2022) A fast and effective analytical method to quantify the emulsifying activity: design and validation. 1st International Conference on Sustainable Chemical and Environmental Engineering (SustEng'2022), 31 August – 4 September, Rethymno, Crete. Proceedings - ISBN 978-618-86417-0-9, p. 334-335