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

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 (G0, G1, G2, G3 and G4).
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 G2 followed by G1 and G3. 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.