Characterization of pectic substances of abu-samaka cultivar in relation to their influence on mango pulp concentrate

Pectic substances of two cultivars of mangoes, namely Abu-Samaka at three different times of the season,beginning (A), peak (B) and end (C) and Baladi were investigated. The mangoes were washed, peeled and sliced. The pulp was then extracted. The total pectin and apparent viscosity in the pulp were determined. The study involved isolation and fractionation of Abu-Samaka mango pulp pectic substances, which were assayed and characterized for their methoxyl content, acetyl content, degree of eslerification, total carboxyl groups, anhydrouronic acid content, equivalent weight, intrinsic viscosity, molecular weight, calcium, magnesium and ash content. The results obtained, indicated that Abu-Samaka mango pulp contains high percentage of pectin compared to Baladi cultivar. Total pectin was found to be 0.78 gm/100gm pulp in sample A and 0.76gm/100 gm pulp in sample B and C, while Baladi cultivar contains 0.345 gm/100 gm pulp. The methoxyl content were 2.118, 2.232 and 2.356% for Abu-Samaka (A, B and C), whereas Baladi contained 1.066%. The acetyl content for Abu-Samaka were 0.314% (A), 0.258% (B) and 0.215% (C), while it was 0.117% for Baladi. The degree of esterification for Abu-S;amaka was 87.0% compared to 70.0% for Baladi. The anhydrouronic acid content was 24.377,25.334 and 26.04% for Abu-Samaka (A, B and C) and was 18.515% for Baladi. The total carboxyl groups were found to be 1.23 meq/gm for Abu-Samaka and 1.143 meq/gm for the Baladi. The equivalent weights were 1389 for Abu-Samaka and 2003 for Baladi. The intrinsic viscosity was 1.43 kl/gm for Abu-Samaka and 0.86 dl/gm for Baladi. The molecular weight was found to b 3.0512 x 104 for Baladi. The treatment of Abu-Samaka mango pulp with different concentrations of pectinease, for different periods of time, resulted in the rduction of the pectin content and consequently the viscosity decreased after enzymetic processing. The standard treatment for best pectin content and viscosity, as Baladi, cultivar, was found to be 0.05% enzyme/30min, at room temperature (30+5"C) or 0.01% enzyme/30 min. at 50"C. The study involved also, concentrating the mango, from both treated pulp and Baladi pulp for comparison. After six months storage at room temperature (30+5"C), the jellying phenomenon fof Abu-Samaka concentrates was not observed. No change in physio-chemical properties was also observed