Microfluidic evaluation of some edible oil quality based on viscosity and interfacial tensions

Abstract

Microfluidic devices were applied to investigate the adulteration of high-quality olive oil and degradation of edible oil over frying. When the inner water flows through the sheath oil flow inside the microfluidic device at specific rates, the inner water flow will be cut into dispersed droplets by the sheath flow. Lengths of the droplets will be dependent on the viscosity and interfacial tension of the sheath oil. As olive oil is adulterated with other oil, its interfacial tension will generally keep constant while its viscosity decreases. As edible oil is used for frying, its interfacial tension will decrease while viscosity increases. As a result, the droplets' length generated in adulterated olive oil and frying oil will be dependent on their adulteration ratio and frying grade. Experiments proved that the tiny, low-cost microfluidic device could be preliminarily implemented to quantitatively evaluate specific oil quality.

Importance of some minor compounds in olive oil authenticity and quality

“…Several recent reviews and studies in the literature provide information regarding the current regulations about olive oil as well as their methods of analysis (Bajoub, Bendini, Fernández-Gutiérrez, & Carrasco-Pancorbo, 2018;Conte et al, 2019;Tena et al, 2015). Some novel techniques (Surface-enhanced Raman spectroscopy (SERS), biosensors, microfluidic devices) have also been applied in olive oil authentication (Bremer, Smits, & Haasnoot, 2009;Deng et al, 2018;Du et al, 2019;McIntosh et al, 2016) and in determination of some bioactive compounds of olive oils especially polyphenolic content (Al Mughairy, Al-Lawati, & Suliman, 2019;Camerlingo, Portaccio, Delfino, & Lepore, 2019;Hammami, Kuliček, & Raouafi, 2016;Ramos, Contreras, & Macías, 2020). Some well-known minor compounds such as sterols, stigmastadienes, aliphatic hydrocarbons and phenolic compounds along with major compounds (triacylglycerols, fatty acid contents) which have official limits in regulations were evaluated in detail in the previous reviews (Aparicio, Conte, & Fiebig, 2013;Arvanitoyannis & Vlachos, 2007;Ben-Ayed, Kamoun-Grati, & Rebai, 2013;Boskou, 2008;García González et al, 2018;Montealegre, Alegre, & García-Ruiz, 2010) Olive oil is very rich in terms of phenolic compounds such as hydroxytyrosol, tyrosol and oleuropein.…”

Frying Oil Evaluation by a Portable Sensor Based on Dielectric Constant Measurement

“…This relationship leads to increased viscosity and decreased interfacial tension, which are two factors that are considered useful indicators of frying oil quality in conjunction with TPM [10][11][12][13][14]. Other researchers have developed pore-based wicking sensors [15,16] and microfluidic methods [17,18], which function based on changing viscosity and interfacial tension and proved feasible for frying oil evaluation as their correlation with TPM is also quite satisfactory.…”

Educational Tool for Determining Viscosity Coefficient of Cooking Oil Using Arduino UNO

“…This study utilized reliable and accurate methods for viscosity measurement to evaluate oil quality, and the research findings indicated a significant relationship between viscosity values and the quality of oil used in food processing. These findings offer a deeper understanding of the significance of viscosity measurement in assessing and ensuring the quality of oil used in the food industry (Deng et al, 2018).…”