ASSESSING THE EFFECTS OF TWO FERMENTATION MEHODS ON THE PHYSICO-CHEMICAL, MICROBIOLOGICAL AND SENSORY PROPERTIES OF "PLACALI" DERIVED FROM THREE IMPROVED CASSAVA VARIETIES
Description
Cassava (Manihot esculenta Crantz) is one of the world's main starchy root and tuber crops. In Côte d'Ivoire, cassava is a very important crop because Cassava therefore plays an important role in addressing the food insecurity problems in drought affected region. Despite its potential, cassava faces storage problems due to its perishability and hydrocyanic acid content. To solve these problems, new resistant varieties rich in beta carotene have been developed as well as processing methods leading to the production of several dishes such as placali. The general objective of this study is to evalute the impact of two types of ferments on the quality of placali obtained from improved cassava varieties. The results showed that placali samples prepared with dried ferment (FS) showed the best characteristics. Indeed, fresh FS placali pastes were less acidic, with a low hydrocyanic acid content. In addition, the dry matter content of FS pasta was higher, which would extend its shelf life. Also, the dried ferment showed a high fermentative power, as 0.5 Kg of dried ferment fermented 10 Kg of cassava chips, compared with 1 Kg of boiled ferment for 10 Kg of cassava. Sensory analysis showed that the FS placali was the most appreciated, as it was less acidic with a slight ferment aroma. It would therefore be interesting to encourage female placali producers to use this ferment to standardize and improve placali quality in Côte d'Ivoire.
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Two preparation methods were used to obtain the ferments responsible for fermenting cassava paste; boiling and drying. For boiled Ferment (FB) cassava roots were peeled, washed with potable water and cut into pieces. The pieces were then cooked in boiling water (100°C) for 10 min. After cooking, the roots were air-cooled, then stored in a jute bag for 72 hours. For dried ferment, cassava pieces were soaked for 24 h in cassava pressing juice obtained during previous fermentations. After 24 h, the cassava pieces were sun-dried for 2-3 days. Paste of cassava was prepared in several stages. The cassava roots were peeled and cut manually with stainless steel knives. The pieces were then washed three times with tap water. For each variety, 10 Kg of cassava pieces were used for grinding. Before grinding, 0.5 Kg of previously prepared dried ferment was added to the different batches for the preparation of placali (FS) and 1 Kg of boiled ferment for the preparation of placali (FB). The whole batch (pieces + ferment) was progressively introduced into an electric grinder to obtain a homogeneous paste. After grinding, the various pastes were packed in jute sacks and left to ferment in large baskets under heavyweight pressure for 18 hours. After fermentation, the pasta was pressed for 2 h to extract the water, using a manual press. The pasta samples obtained were used firstly to determine physico-chemical (pH, moisture content, ash content, Hydrogen cyanide, carotenoid content), microbiological, and secondly to prepare the placali. For microbiology analysis, the stock solution and decimal dilutions were prepared in accordance with ISO 6887-1: 1999. The results, expressed in CFU/g, were obtained in accordance with NF ISO 4833, using the formula below. N=(∑C)/(dV x (n1+0,1n2)) N = number of colonies ; ∑C = total sum of colonies counted on the retained plates; V = volume of inoculum ; d = first dilution considered; n1 = number of plates at the first dilution considered; n2 = number of boxes at the second dilution considered For the preparation of placali, 100g of fermented cassava paste was diluted in 150 ml of cold water. The filtrate in a pot was then brought to the boil while stirring with a wooden spatula until thickened. As soon as the paste was homogeneous, it was covered and left to cook over low heat for 10 min. The paste was removed from the heat when a thick, translucent mass was obtained. After cooking the cassava pastes of each variety, the Placali samples were packed in a sealed jar and taken to a room for tasting. The trained panel comprised 15 people. Two tests were carried out: a hedonic test and a descriptive test. Six sensory attributes were selected for the placali. These were color, elasticity, finger firmness, aroma (ferment), sour taste and sweetness. The ratings ranged from 1 to 10, with 1 corresponding to "very bad" and 10 to "very good", making it possible to compare Placali from the four cassava varieties.