A study of radiation and natural convection of air on drying of coffee beans in a heat recovery solar dryer

A solar heat recovery dryer for drying coffee beans was designed and tested based on heat recovery through condensation. A mathematical model of the dryer was built based on heat and mass transfer, fluid flow and boundary analysis. Experimental data from the first run was used to estimate two critical constants in the model, and seven subsequent runs at different conditions were used to validate the model. The simulated results and the experimental data correlated well (r = 0.97). Design of the solar heat recovery dryer was then optimized in terms of annual profit, estimated from operation, maintenance, construction and product costs. The three parameters optimized were the dryer height, length, and the depth of the coffee bed. A sensitivity analysis of the profit equation showed that the tray area, density of coffee beans and the price of labour had the most effect on profit. From this, a suitable design of the solar heat recovery dryer was developed for local conditions

Microencapsulation of Xanthone extracted from Garcinia Mangostana pericarp using freeze drying / Ummi Kalthum Ibrahim... [et al.]

Garcinia mangostana fruit is one of the most popular fruit and known as a tropical fruit that has high nutrition value and widely cultivated in the tropical rainforest of some Southeast Asian nations. The main objectives of this research were to identify the composition of extracted xanthones and to determine the antioxidant activity, total phenolic content, moisture content and antimicrobial activity of encapsulated Garcinia mangostana pericarp. Encapsulation process was done by using freeze drying technique. Antioxidant activity, total phenolic content, moisture content and antimicrobial activity of encapsulated xanthones analysis were conducted. The amount of xanthones was detected at range of 515 to 4000 cm⁻ 1 through Fourier transforms infrared spectroscopy (FTIR). The highest value of radical scavenging activity for non-encapsulated xanthones was 82.69% whereas 88.01% for encapsulated xanthones. The total phenolic content (TPC) was found 5.240 mg GAE/g and 6.359 mg GAE/g for non-encapsulated and encapsulated samples, respectively. In conclusion, encapsulated xanthones from Garcinia mangostana pericarp has high antioxidant activity and antibacterial properties which has potential to the manufacturing functional food, cosmeceutical and pharmaceutical industries