Co-encapsulation of vitamin E and Coenzyme Q10 with different blends of protein and carbohydrate through microfluidic jet spray dryer

Abstract

Vitamin E and coenzyme Q10 (CoQ10) exhibit effective antioxidant activity which can be enhanced through their synergistic interaction. Lacking these two antioxidants may lead to serious disease in human. However, both antioxidants are sensitive to environmental factors including oxygen, light and heat. Also, they are highly lipophilic that largely limits their applicability in food. Therefore, microencapsulation of these two components through spray drying may enhance their stability and application in food systems. However, conventional spray dryer produces polydispersed microcapsules which may hinder the efficient handling of powder as well as allowing droplets to experience different evaporation process during the constant drying condition. Hence, this study aimed to co-encapsulate vitamin E with CoQ10 using milk proteins and carbohydrates through microfluidic jet spray dryer (MFJSD) to determine the synergistic antioxidant activity of vitamin E and CoQ10 in microcapsules as well as enhancing their stability and applicability in food system. Whey protein isolate (WPI) is widely used emulsifier to encapsulate food ingredients that also exhibit antioxidant activity. Carbohydrates are also commonly used as stabilisers and blending proteins with carbohydrate is known to improve encapsulation efficiency and stability of microcapsules. Therefore, maltodextrin (National M3) and soluble corn fibre (PromitorTM soluble corn fibre 70) were employed as stabilisers. By blending with WPI, these carbohydrates were used to encapsulate vitamin E and CoQ10. Wall materials were dispersed in water either blended or alone to prepare the wall solution with 30% solids. The emulsions containing vitamin E and CoQ10 were produced by ultraturrax homogeniser at 13,500 rpm which was further homogenised by nano-homogenize machine at 800 ± 50 bars for 6 passes. The conversion of emulsion into powders were achieved by spray drying at 190ºC inlet and 90ºC outlet air temperature using disturbance frequency between 6,000 to 8,000 kHz. The emulsion characteristics studied were emulsion droplet size, size distribution, viscosity and its stability. The properties of powder were determined including moisture content, density, flowability, wettability, morphology, core material retention. The storage stability of microcapsulesat room temperature was carried out by evaluating change in the colour, microencapsulation efficiency and oxidative stability of microcapsules. Microcapsule digestibility was assessed by using in vitro digestion study. Results describe that the droplet size of all emulsions was below 200 nm with narrow size distribution. The viscosity of the emulsions was low and visual observation with emulsion droplet measurement indicated the sufficient stability of emulsions during spray drying. Microcapsules prepared by WPI had the highest mean moisture content where the mean density was the greatest in microcapsules prepared by WPI and SCF and the lowest powder flowability was indicated from microcapsules prepared by WPI and M3. The wetting time of microcapsule was the longest in microcapsules prepared by WPI compare to the blend WPI with carbohydrates. Scanning electron microscopy showed the apparent surface cracks on microcapsule prepared by WPI and surface dents on microcapsule prepared by WPI and WPI with M3. Uniformity in the size of microcapsules was apparent in microcapsules produced by WPI and WPI with SCF. The retention of core materials in all microcapsule was above 90%, indicating effective retention of core materials in microcapsules. Storage test performed at room temperature (=25°C) determined that the initial microencapsulation efficiency of all microcapsules was 90% that slightly reduced over time. This proves the effectiveness of wall system against organic solvent penetration through the wall matrices. Colour parameters measured during the storage test show that the original colour of the wall materials and non-enzymatic browning occurred between wall materials can influence the overall colour of microcapsules. Oxidative stability results conducted for storage trial showed that co-encapsulating vitamin E with CoQ10 improved the oxidative stability of microcapsules regardless of wall materials used. However, the best synergistic antioxidant activity between vitamin E and CoQ10 was observed from microcapsules prepared byWPI with M3 indicated by the lowest IC50 value. Hence, blending WPI with M3 might give the best synergistic activity when co-encapsulating vitamin E with CoQ10 together. The in vitro oral and gastric digestion phase results show that microcapsules prepared by WPI or WPI with M3 would provide better protection of core materials than that microcapsules prepared by WPI with SCF during digestion. This is because microcapsules prepared by WPI with SCF turned into watery state immediately after the contact with water and thus core contents would be destroyed during gastric phase of digestion before reaching intestinal phase. In summary, this study has illustrated that co-encapsulating of vitamin E with CoQ10 by using MFJSD is suitable to produce microcapsules showing synergistic activity between core materials with good stability which potentially be able to be applied in food system.