Thermal Inactivation of Crude Polyphenol Oxidases and Peroxidase from Three Tissues of Yellow-fleshed Cassava (Manihot esculenta Crantz) Root cv. Bocou 2

Aims: The objective of this work was to study the thermal inactivation of the polyphenol oxidase (PPO) and peroxidase (POD) activities of cassava (Manihot esculentaCrantz) root cv. Bocou 2 in order to preventenzymatic browning.Study Design: Crude PPO and POD from yellow-fleshed cassava root were subjected to heat treatment and their thermal inactivation characteristics were examined.Place and Duration of the Study: The study was conducted at Biocatalysisand Bioprocesses Laboratory, Food Science and Technology Unit, Nangui Abrogoua University Abidjan, Côte d’Ivoire, between January and December 2015.Methodology: The crude PPO and POD were extracted from three tissues (cortex, cambium and central pith) ofyellow-fleshed cassava root cv. Bocou 2. The thermal inactivation of these enzymatic activities was evaluated between 50 and 70 °C. The kinetic data of thermal inactivation and thermodynamics were analysed. Results: The t1/2-and D-values decreased with increasing temperature, indicating a faster inactivation of PPO and POD at higher temperatures. Z-values ranged from 16.10 to 27.70 °C and activation energy (Ea) from 73.37 to 129.66 kJ mol-1. Thermodynamic investigations indicated that the oxidation reactions involving these enzyme activities were: not spontaneous (?G > 0), slightly endothermic (?H > 0) and reversible (?S < 0).Conclusion: The PPO and POD activities from yellow-fleshed cassava root decreased due to heat denaturation with increasing temperature from 60 to 70 °C. These kinetic data can be used to prevent enzymatic browning in cassava roots.

Protein Fractions and Functional Properties of Dried Imbrasia oyemensis Larvae Full-Fat and Defatted Flours.

Aims: To assess the functional properties of flours made from Imbrasia oyemensis larvae, a caterpillar widely consumed in Côte d’Ivoire, for industrial purposes. Methodology: Full-fat and defatted flours were obtained from dried Imbrasia oyemensis larvae collected on the “Gouro” market of Adjamé (Abidjan, Côte d’Ivoire). Protein fractionation, protein content and functional properties were investigated using standard methods. All results were statistically analysed. Results: Defatting led to a significant (P≤0.05) reduction of emulsion capacity and stability, whereas the soluble protein fractions (such as albumin and glutelin), dispersibility, bulk density, water absorption capacity, water solubility index, oil absorption capacity, foam capacity and stability increased significantly (p<0.05). The full-fat and defatted flours had high oil (78.12 and 84.08% respectively) and water absorption capacities (86.89% for full-fat and 66.07% for defatted flour) as desirable characteristics for use in some foods such as meats, sausages, breads and cakes. Fevermore, they showed high bulk density (1.00 and 1.04g/mL respectively for full-fat and defatted) and good wettability and therefore would be suitable for use as a functional ingredient in a variety of food formulations. Conclusion: Defatting has significant effect on functional properties of dried I. oyemensis flours. Full-fat as well as defatted flour show good functional characteristics for use in many food industries.