High efficiency microencapsulation of extra virgin olive oil (EVOO) with novel carrier agents: Fruit proteins

Abstract

Coating materials are incorporated into microencapsulation systems for improving stability against environmental stress and functionality (such as hydrophilic features) of sensitive food products (core materials) having desirable nutrition profiles. Assuming that the final powder products containing these materials in a high proportion (at least 50%) will be offered for consumption, it is essential to include coating materials with health beneficial effects in these systems to reach exactly the desired objectives. Therefore, many studies are interested in reducing the applications of carbohydrates used commonly in microencapsulation techniques. In this context, proteins, especially plant-based alternatives obtained from food processing by-products draw attention. Similarly, the current study focused on the utilization of sour cherry protein isolate (SCPI) and pomegranate protein isolate (POPI) as novel (innovative) coating materials in the microencapsulation of extra virgin olive oil (EVOO). The EVOO was also loaded into commercial proteins including pea protein isolate (PPI) and gelatin protein isolate (GPI). The spray dryer air inlet temperature for microencapsulation step of prepared emulsions (the ratio of EVOO to protein, 1:1) was 160 °C. Microencapsulation efficiency (MEE) was 97.71%, 90.27%, 89.55%, and 88.15% for sour cherry protein microcapsules (SCPM), pomegranate protein microcapsules (POPM), pea protein microcapsules (PPM), and gelatin protein microcapsules (GPM), respectively. On the other hand, POPI loaded with EVOO showed superior microencapsulation yield (MY) (60.50%) compared to PPIM (48.50), SCPIM (42.35%), and GPIM (33.30%). The impact of proteins on the morphology and particle size of microcapsules was also established. Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), and x-ray diffraction (XRD) analyses were conducted to confirm the presence of EVOO in the protein matrix. Thermogravimetric analysis (TGA) results showed that the maximum decomposition temperature of all samples was between 200 and 500 °C but mass loses rates differed in these temperatures. SCPI and POPI were required for providing higher thermal stability to EVOO rather than commercial proteins. Novel plant-based proteins and commercial proteins loaded with EVOO showed similar limitations against the oil oxidation and no significant increase in the peroxide value of encapsulated EVOO at 60 °C during 7 days of storage were noted. The results support such fruit proteins for commercial production to use in microencapsulation applications as coating materials.