Response surface optimisation of process variables for encapsulation of cumin oil by spray drying

Abstract

Spices are the main flavouring agents in food. Cumin (Cuminum cyminum Linn.) is one of the important commercial seed spices which belong to the umbellifereae family. Cumin is valued for its aroma, medicinal and therapeutic properties. The most important chemical component of cumin seed is essential oil content, ranging from 2.5 to 4.5%. The biological activity of the oil is lost due to the volatilisation or degradation of active compounds owing to direct exposure to heat, humidity, light, or oxygen. Encapsulation is the most suitable method which will protect the essential oil and flavour ingredients from the liquid form to solid form by coating agents. Microencapsulation and nanoencapsulation are the two encapsulating techniques commonly used. Spray drying is the most commonly used technique for encapsulation in the food industry as it is a rapid, continuous, cost-effective, reproducible and scalable process for the production of dry powders from a fluid material. The microencapsulation of cumin oil were carried out with a tall type spray dryer with twin fluid atomiser whereas the nanoencapsulation was done in a laboratory spray dryer with ultrasonic atomiser. The wall materials selected for encapsulation were gum arabic and maltodextrin. The process variables used in the study were gum arabic: maltodextrin ratio (1:2, 1:3 and 1:4), core concentration (10, 20, and 30%) and spray dryer inlet temperature (150, 160 and 170°C). The pysico-chemical properties of cumin oil and wall materials were determined. The optimisation of the encapsulation process was done with RSM (Response Surface Methodology) from the quality characteristics of the encapsulated powders. The optimised condition in microencapsulation were 1: 2.77 carrier blend ratio (gum arabic:maltodextrin), 10% core concentarion and 162.50°C spray dryer inlet temperature and that for nanoencapsulation were a carrier blend ratio of 1:2.92, core concentration of 10% and a spray dryer inlet temperature of 163.38°C. The total cost for the production of 1 kg of microencapsulted cuminn oil were Rs. 1577/kg and that for nanoencapsyulation were Rs. 13510.7/kg.