DEVELOPMENT OF AIR BLAST FREEZER FOR THE STORAGE OF SOME FRUITS

Abstract

The need for conservation of Agricultural produce is highly essential considering the global food crisis. Several methods of food preservation do not normally conserve the organoleptic and nutritional value of the preserved food. The development of blast freezer gives room for conservation of nutritional and organoleptic values of compatible fruits and vegetables. In this work, a blast freezer was designed for a maximum load of 20 kg. The various heat loads to the refrigerating chamber were considered in the design and a fan was incorporated into the refrigerating chamber for the purpose of circulating the cold air around the finned evaporator. The system was tested under no-load and load conditions, during the test, the parameters required for the evaluation of the system were measured. These parameters include flow rate, ambient, condensing and evaporating temperatures which were used to determine important parameters such as Refrigerating Effect, Compression Work and Coefficient of Performance of the system. Refrigerant 134a was used because it is one of the adjudge environmental friendly refrigerantg. Afterwards, three fruit samples viz: grape, orange and apple were stored for the period of seven days. The organoleptic and nutritional characteristics were determined before the storage and after the storage. Samples were selected from the fruits and left in the open space in the laboratory and were also analyzed at the end of seventh days. The results were compared with the sample stored in the system and analysis shows that the preserved products were able to retain most of the organoleptic and nutritional values while the control sample lost most of its organoleptic and nutritional values when compared with the state of the produce when fresh