Kinetics of acidification and production of α-amylase, β-glucosidase and pectinase of three types of freeze-dried ferments for the production of quality attieke in Côte d'Ivoire

Abstract

The long-term availability of cassava ferment for the production of cassava of consistent, healthy quality is a problem in Côte d'Ivoire. To this end, three types of traditional ferment, namely braised, raw and boiled ferment, were freeze-dried. The aim of this work was to determine the ideal inoculation dose for each freeze-dried ferment for the production of attieke. For the same type of lyophilized ferment, doses of 5%, 10%, 15% and 20% were used to inoculate 4 batches of cassava dough. The fermentations were carried out for 24 hours at 35°C. During fermentation, samples were taken every 6 hours to assess the four main technological activities of a good Attieke ferment, i.e. rapid acidification, production of α-amylase, β-glucosidase and pectinases, corresponding to the respective attributes of acidity, flavour synthesis, detoxification and softening. Irrespective of the type of ferment considered, the results showed that the fermentation properties of the dough inoculated with 10% traditional ferment were similar to those of the dough inoculated with 10% freeze-dried ferment. The dough inoculated with 10% freeze-dried raw ferment had the highest acidity level of 0.97±0.1%, compared with 0.64±0.3% for the dough inoculated with 10% freeze-dried braised ferment and 0.63±0.2% for the dough inoculated with 10% freeze-dried boiled ferment after 24 hours of fermentation. Similarly, the production kinetics of α-amylolytic, β-glucosidase and pectinolytic activities are generally characterised by inactivation or repression after 18 h of fermentation, after which production is low or progressively reduced.  At this time, the high amylolytic activity of 75.78±1.9 U/mL was recorded in the dough inoculated with 10% of the raw ferment. On the other hand, the high kinetics of β-glucosidase production (68.34±0.9 U/mL) was obtained in the cassava dough inoculated with 10% freeze-dried braised ferment. The highest yield of pectinolytic activity (24.5±0.09 U/mL) was obtained in cassava dough inoculated with 10% boiled freeze-dried ferment. The metabolic activity of the lyophilised ferment was maximal at an inoculation dose of 10%, after 18 hours of fermentation at 35°C.