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Heart of oil palm tree (Elaeis guineensis Jacq.), little known, is a vegetable consumed after boiling. This study is an evaluation of the impact of boiling times (15,30,45 min) on physicochemical and nutritive composition of this vegetable. Moisture, fiber and carbohydrate contents differ significantly (p<0.05) and increased in all three parts (PP, MP, DP) during boiling times. Moisture contents (%) varied from 89.94±0.08 (PP 0 ) to 92.23±0.15 (PP 45 ), 88.13±0.27 (MP 0 ) to 89.75±0.97 (MP 45 ) and 91.38±0.5 (DP 0 ) to 92.08±1.49 (DP 45 ). Fibers contents (%) varied from 26.49±0.13 (PP 0 ) to 32.26±6,89 (PP 45 ), 34.90±0.01(MP 0 ) to 37.67±1.12 (MP 45 ) and 21.9±0.02 (DP 0 ) to 29.41±2.63

In Côte d'Ivoire, cashew apples represent waste in plantations due to lack of processing. This study deals with their transformation into jam for a better valorization. Cashew apple jam were analyzed for physicochemical and sensory properties. Proximate physiochemical were determined using standard analytical procedures and the sensory acceptance test was performed by 50 panelists on the following attributes. Proximate result showed that moisture content of cashew apple jam was 26.5±1.77% ; carbohydrate 67.7±02.45%, protein 0.7±0.01%; fat and ash contents were 0.16±0.0 and 2.4±0.01% for respectively. pH and titratable acidity were 3.9±0.01 0.06% respectively. Soluble solids (°Brix) was 25±0.98%. Vitamin C and total sugar contents were 276±4.67 (mg/100g) and 51.87±2.18% respectively. Major minerals in the jam were potassium (2762±43.2 mg/Kg), phosphorus (298±4.1 mg/Kg), magnesium (146±1.1 mg/Kg) and calcium (143±2.21mg/Kg). phytochemical analysis revealed presence of tannins (0.8±0.01%), phenol (0.35±0.02%), oxalate (1.87±0.02%) carotenoids (0.70±0.01%), flavonoid (0.20±0.01%), phytate (1.16±0.03%) Results from sensory analysis showed color (7.88±0.55), consistency (8.22±0.83), sweet (8.44±1.09) odour (5.4±0.36) and general acceptability 5.22. Parameters (acidity, astringency and afteraste) scores are less than 3.

Enzymatic browning is associated with the action of polyphenol oxidases (PPO) and peroxidases (POD). The products of these enzymes cause undesirable changes of color and flavor of processed eggplant products. The present study aimed to evaluate kinetic properties and thermodynamics parameters of PPO and POD activities for controlling this undesirable process in extract from of violet eggplant. The effect of heat treatment on polyphenol oxidase and peroxidase activities in violet eggplant were studied over a range of 30 to 80 °C. T1/2-values of enzymatic activities are between 6.15 ± 0.03 and 13,27 ± 0,04 min at 80 °C, they decreased with increasing temperature, indicating a difference thermostability of each enzyme. D- and k-values decreased and increased, respectively, with increasing temperature, indicating faster of these enzymes inactivation at higher temperatures. Results suggested that polyphenol oxydase and peroxidase were relatively thermostable enzymes with a Z-value which from 50.25 and from 88.33 °C and Ea of 41.21 and of 27.78 kJmol-1. Thermodynamic parameters were also calculated. The Gibbs free energy ΔG values range from 43.24 ± 0,03 to 91.45 ± 0,01 kJ/mol. These kinetic data can be used to predict prevention of browning in the violet eggplant (Solanum melongena L.) by thermal inactivation of enzymes.

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