DETERMINATION OF SPECIFIC HEAT CAPACITY FOR FOOD ITEMS

Abstract

The primary objective of this study was to determine the specific heat capacity of various food items experimentally. The study involved the development of the experimental setup and the execution of the experiment on some selected food items. An indirect calorimetric method of mixture experimental setup has been developed to determine the specific heats of some selected foods and prepared traditional foods mainly found in Ethiopia, which is commonly known as Injera. This method involved the modification of a heat preservation portable food storage container, purchased from a local market, to serve as a calorimeter. The calorimeter utilized in this study was a 1.9-liter wide-mouth, vacuum flask designed to keep food at a desired temperature for an extended period by minimizing heat transfer with its surroundings. Initially, four runs were conducted for the determination of the calorimeter’s specific heat capacity by employing hot water, which is found to be an average 1.003 kJ/oC. It is important to note that the plastic pouch is considered to be an integral component of the calorimeter, as both the calorimeter and plastic pouch were acquired from the local market. To prevent direct contact between the food sample and the heat exchange medium within the calorimeter, the food sample was placed within the plastic pouches. Consequently; the assessment of heat solution for dissolved chemicals in food was eliminated. The specific heat values of carrots, potatoes, onions, cabbage and Injera using predictive models at an average temperature were determined as 4.365, 4.086,4.423, 4.505 and 3.433 kJ/(kg oC), and the experimental results of these foods were found to be 4.671, 4.290, 4.688, 4.820 and 3.710 kJ/(kg oC) respectively, here the same amount of mass of samples and water, materials and methodology, by the indirect method of a mixture of calorimetry is used. Also four trials are were conducted for the determination of the specific heat capacity of potatoes, carrots, onions, cabbage and Injera. The comparison between the experimental and the predictive models exhibited an excellent level of agreement with percentage error of 5% to 10% for the above foods. This indicates that experimental specific heat capacity measurement is consistent and validate with the predictive value within an acceptable range of error.