Evaluation of the gelling effect of Gracilaria debilis agar in the preparation of a tomato-based sauce

Abstract

In the present investigation, the gelling effect of Gracilaria debilis agar was evaluated in the preparation of a tomato-based sauce, for which the algae after being collected, washed and dried, were applied alkaline treatment with NaOH 0,04 mol/L. The agar extracted from G. debilis had a yield of 2.,4±0,3%, the analysis: gelation point (37,3±0,6 °C), melting point (78,3±0,6 °C) and gel strength (256,8±3,5 g/cm2) are within the agar quality ranges reported by the Food and Agriculture Organization of the United Nations (FAO). With the agar and a mother sauce prepared with onion, salt, vinegar, spices and tomatoes previously blanched and without seeds, three tomato-based sauces (S1, S2, and S3) were prepared with concentrations of 0,5; 1,0 and 1,5% w/w agar respectively. Sensory analysis indicated that S2 with 1,0% agar was the most acceptable. The viscosity index of S2 was -729,7±9,8 g.s, which is not significantly different from the value of a commercial sauce studied (-766,3±15,6 g·s). Agar concentrations influenced only the viscosity index parameter by adjusting to a linear equation with R² = 0,996. As the agar is a product of great utility at the industrial level, its use as a gelling agent in a tomato-based sauce is expected to promote its elaboration, encouraging national production and reducing the dependence on the importation of gelling agent.