Effect of Fermentation Time on the Physicochemical and Sensorial Properties of Gari from Sweet Potato (Ipomoae batatas)

Abstract

Aims: This study aims to investigate the sensorial and physicochemical suitability of sweet potato to be processed into gari. Study Design: TiB1 potatoes variety were grated and the obtained paste was left to ferment for 0, 1, 2, 3 or 4 days. Different fermented pastes were roasted at 90ºC with palm oil to obtain the various garis (G 0 , G 1 , G 2 , G 3 and G 4). Place and Duration of Study: This study was carried out in the Life and Earth Science Laboratory, at the University of Maroua, Cameroon between the periods of January to April 2013. Methodology: The physicochemical characteristics, hydratation capacities and sensory properties of the different products were evaluated. The analysis were done by using a commercial cassava gari as reference. Results: Results showed that the fermentation time (p = 0.05) affects significantly the physicochemical properties and sensory attributes of the garis. Decrease of pH, ash content (19 to 11%), phenolic compounds content (8 to 5 mg / g), soluble sugars and starch content (17-13%) have been observed during fermentation. But in contract the titrable acidity (9 to 27 mg acetic acid / g), the bulk volume, the gel strength (12 to 24 g/100 mL) and protein content (10 to 14%) increased during fermentation process. Comparatively to potato gari, cassava gari exhibited a high titrable acidity (26 mg acetic acid / g), starch (23%) and protein content (15%) but low phenolic compounds (2.94 mg / g), free sugars content (1.01 mg / g) and the best hydration capacity. According to physicochemical analysis and organoleptic tests, the best potato gari is G 2 followed by G 1 and G 3. Color, mouth feel and acidity as well as food habit were found to be the determining attributes for panellists' preference. Conclusion: From the present results, processing sweet potatoes into gariis one of a good way to reduce post-harvest losses.