Microencapsulation of Rice Bran Oil by Spray Drying and its Application in Producing High Quality Yoghurt

Document Type : Original Article

Authors

1 Fats and Oils Res. Dep., Food Tech. Research Institute,Agric. Res. Center, Giza, Egypt.

2 Food Sci. Dep., Faculty of Agric. Saba Basha, Alex. Univ., Alexandria, Egypt

3 Oils and Fats Dep., Food Tech. and Nutrition Research Division, NRC., Egypt.

4 Food Sci. Dep., Faculty of Agric. Saba Basha, Alex. Univ.,Alexandria, Egypt.

Abstract

The present study aimed to evaluate microencapsulated rice bran oil as a potential source of bioactive compounds and to utilize it in preparing functional yoghurt. Rice bran oil (RBO) was extracted from rice bran as a by-product by hydraulic press. RBO was encapsulated by spray-drying with wall materials such as maltodextrin (MD): Whey protein concentrate (WPC), MD:WPC: gum arabic (GA) and MD:GA at ratios (3:2), (3:1:1) and (3:2), respectively. The ratios between rice bran oil (RBO) (core) and coating materials were 1:2 and 1:4. Physico-chemical characteristics and bioactive compounds were measured in RBO. The stability, particle size distribution and zeta potential of emulsion were evaluated; also encapsulation efficiency (EE) and surface morphology of capsules powder were studied. Encapsulated rice bran oil (ERBO) was used to fortify yoghurt. Physico-chemical properties (pH value, acidity and WHC) and organoleptic properties were determined during storage periods (zero time, 7 and 14 days) on the fortified yoghurt and control. The study revealed that, the mixture wall material with MD: GA at ratio 3:2 and core: coating materials at ratio 1:4 were found to be the best effective on emulsion stability (100%) with no separation phase, particle size distribution (249.8 nm.), zeta potential (-31.49 mV). Use of MD: GA as a wall material with core to coat material at ratios 1:4 for encapsulation of RBO caused a decreased in the surface oil content (0.22) and an increase in EE (78%). The particles of capsules powder obtained from MD: GA at 3:2 ratio with core to coat material at ratios 1:2 and 1:4 are smooth spheres with little appendages and no cracks or fissures. Adding powder of ERBO at different concentrations (2, 4 and 6%) and RBO at 2% to yoghurt samples caused a decrease in pH and increase in values of acidity and WHC during the storage period. According to the results obtained, there were changes in values of organoleptic parameters of control and different tested levels of supplemented yoghurt samples with RBO and ERBO during the storage periods, these changes were still within the acceptable scores and satisfaction panelists. 
 

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