A Fluorescence‐based Method for Estimation of Oxygen Barrier Properties of Microspheres

Abstract

In this study, we developed a fluorescence method to quantify oxygen barrier properties for wall materials used in microencapsulation of oxygen‐sensitive compounds. We used a reversible, oxygen quenching dye, tris (4,7‐diphenyl‐1, 10‐phenanthroline) ruthenium(II) dichloride complex, as a marker to monitor oxygen transport across spray‐dried and freeze‐dried Hi‐cap100 and maltodextrin microspheres. We fit the rate of oxygen transport to Fick's second law and extrapolated an effective oxygen diffusion coefficient Deff. Results show that the Deff for spray‐dried maltodextrin and Hi‐cap100 formulations were in the range of 6.46 × 10−15 to 7.45 × 10−15 m2/s and 16.0 × 10−15 to 22.4 × 10−15 m2/s, respectively. Results also show an increasing trend in thiobarbituric acid reactive substances reaction rate constants, with an increasing Deff for each formulation. Additionally, freeze‐dried maltodextrin formulations had significantly higher Deff (31.1 × 10−15 to 36.0 × 10−15 m2/s) compared to spray‐dried matrices due to a more porous morphology. This new method provides a framework for the in situ estimation of Deff for wall materials in microspheres. Potential applications include the design and selection of wall materials for maximum oxidative stability of encapsulated ingredients. Practical Application Currently, the selection of wall materials used in microencapsulation of lipids takes a trial‐and‐error approach, which can be time consuming and prone to error. In this study, we developed a new methodology to directly assess the oxygen barrier properties of wall materials in microspheres. This method can be used by food scientists to screen wall materials in order to optimize the oxidative stability of encapsulated lipids.

Improving the oxygen barrier of microcapsules using cellulose nanofibres

“…The values of D eff fall within the range of previous studies, which ranged from 6.46 × 10 −15 m 2 s −1 -22.4 × 10 −15 m 2 s −1 for microcapsules equilibrated at a w = 0.33 (Kak et al, 2019). In particular, Kak et al (2019) reported the D eff for Hi-cap100/MD 23 (1:2) microcapsules as 16.7 × 10 −15 m 2 s −1 , which is similar to that of MD 26 microcapsules. Although GA is generally known to have a poorer oxygen barrier than Hi-cap 100, due to presence of higher concentration of MD present in this study, the D eff for prepared microcapsule is similar to the previously reported range (Carneiro et al, 2013;Granados-Vallejo et al, 2019).…”

“…Although the moisture content was not measured for the equilibrated microcapsules, the moisture content estimated from reported sorption isotherms of MD and GA may be in the range of 8.0–8.5% (Ahmed & Abdelgadir, 2014; Nurhadi et al ., 2016). The values of D eff fall within the range of previous studies, which ranged from 6.46 × 10 −15 m 2 s −1 –22.4 × 10 −15 m 2 s −1 for microcapsules equilibrated at a w = 0.33 (Kak et al ., 2019). In particular, Kak et al .…”

“…This was unexpected as the differences in DE of different MD were not observed using the fluorescence method in Kak et al . (2019). The difference in DE may have been observed in this study as a high proportion of poor barrier GA was utilised; thus, the free volume spaces between the GA molecules would be filled differently by MD with different DE.…”

“…An effective oxygen diffusion coefficient ( D eff ) for all encapsulates equilibrated at water activity of 0.33 was determined using the method by (Kak et al ., 2019). A reversible, oxygen quenching ruthenium dye was incorporated in the oil phase of spray‐dried microcapsules.…”

Development of chitosan based microencapsulated spray dried powder of tuna fish oil: oil load impact and oxidative stability

“…Concept of microencapsulation based on formation of protective barrier around the active ingredient and widely deployed in improvement and preservation of biological and functional element of food (Ray et al, 2016). Microencapsulation functions as a vehicle that carry active components, prevent oxidation and mask the properties like odor and taste that are not desired, so there is extensive use of this technique in food-based industries (Kak et al, 2019).…”