Study on trend of agar melting point and gelling temperature from cultural alga (Gracilariopsis persica) in different extraction conditions

Agar is a gelling biopolymer that can be extracted from cell wall of some red algae. In this present, response surface methodology was used to investigate the procedure of agar melting point and gelling temperature from cultural algae of Gracilariopsis persica. Independent variables, alkalinity concentration (2, 3.2, 5, 6.8, -8%), extraction temperature (90, 96, 105, 114, 120°C) and extraction time (45, 85, 142, 200, 240 minutes) were applied in five levels.
Base on the result effects of extraction temperature and time on melting point were significant (p 0.05). Polynomial models developed for the melting point and gelling temperature indicated that optimum conditions. Optimum data for independent variables were alkality concentration 3.2%, temperature 110 °C and time 200 minutes.
Confirmatory test were earned as follows melting point 102.6±0.84 °C and gelling temperature 38.16±44 °C. Agreement of actual and predicted values was capabilities of models (P> 0.05).
Keywords: Agar, Gelling temperature, Melting point, RSM, Gracilariopsis persica