CHARACTERIZATION AND OPTIMIZATION OF DRYING CONDITIONS OF CACTUS CLADODES (Opuntia ficus-indica) BASED ON THE QUALITY PARAMETERS OF DRIED PRODUCT.

Abstract

Cactus (Opuntia ficus-indica),which was introduced to Ethiopia in 1848, is a drought resistant and lif-saving crop. In Ethiopia, particularly in Tigray, Cactus has been used as a major source of household income and nutrient-rich food. Eventhough Cactus cladodes are processed into flour via optimization of drying condition to use in various food industries globally, this practice is not yet adopted in Ethiopia. Therefore, the main objective of this thesis work was to optimize the drying process of cactus cladode for the purpose of powder production based on the drying temperature (55, 65 and 75 oC), pretreatment (unblanched, blanched with and without removing skin) and slice thickness (0.5, 1 and 1.5 cm) factors. The experiemt was designed with factors in full factorial arrangement of 3x3x3 in a completely randomized design (CRD) with three replications. The functional properties, phytochemicals and anti-nutritional factorsof cladodes powder were analaysed by response-surface method of Box-Behnken design using Design Expert software (version 6.0.8). The Curve Expert 32 (version 1.4) was applied to select the best fitting model and get the various equations used for the ploting of the graph of moister ratio and drying rate based on the value of R2 and standard devaition, while the Design Expert software (version 6.0.8) was used to fit various responses. The obtained data of proximate composition and mineral contents were statistically interpreted using one-way ANOVA. The findings of this study indicated that the moister content of fresh and dried powder of leaf of Cladodes was obtained 87.81% and 7%, respectively. The values of water abospriton capacity, water solubility index, and chlorophylla for the unblanched, blanched with and without removing skin of the cladodes’ leaves were found to be 5.63 g/g-26.73g/g, 24.17%-45% and 0.032 mg/g-0.041 mg/g, respectively. In this finding, the un-blanching treatement, drying temperature of 55 °C, and a slice thickness of 1.5 cm were found to be the optimal conditions for the drying process of cladodes’ leaves. In conclusion, the majority of the proximate compositions and mineral contents were not significantly affected by drying temperature and slice thickness. The anti-nutrient contents were not affected at all by the indicated factors. It is recommended that further research on the determination of shelf-life of dried powder of various species and its application for the formulation of various food products be conducted