Cassava leaves are a crucial source of alternative protein resources for both humans and livestock in developing societies in African and Asian countries that do not have easy access to available protein sources. Hence, cassava has the capacity to promote the economic development of these countries and provide food security. However, it has some disadvantages due to the anti-nutrient compounds present in its tissues, which limits the nutritional value of cassava leaves. Thus, proper processing of cassava leaves is essential in order to reduce the anti-nutrients to a safer limit before utilization. This study focuses on reducing the tannin content of cassava leaves during solid-state fermentation using Saccharomyces cerevisiae . In addition, the Box-Behnken design of the Response Surface Methodology was applied to optimize various process parameters, such as carbon concentration, nitrogen concentration, moisture content, and incubation time for maximum reduction of tannin content in cassava leaves. A quadratic model was developed for the reduction of tannin content, which resulted in a perfect fit of the experimental data (p < 0.01). The optimal conditions were found at 1.4% (w/w) of carbon concentration, 0.55% (w/w) of nitrogen concentration, 57% (v/w) moisture content, and an incubation time of 96 h. The minimum tannin content obtained under these conditions was 0.125%, which indicated a reduction of 89.32 % in tannin content. Conversely, the protein content was increased with a further increase in fermentation time from 24 to 96 h (from 10.08 to 14.11–16.07 %). Furthermore, the ability of Saccharomyces cerevisiae to produce tannase under solid-state fermentation of cassava leaves was also studied. The maximum yield was obtained with an enzyme activity of 0.53 U/gds after 72 h of incubation.
Cassava leaves are a good source of protein. However, their use is limited because of the presence of cyanogenic glucosides. These require a further detoxification process in order to reduce the cyanide to a safe level prior to human consumption. The main objectives of this work are: (i) to demonstrate the effectiveness of solid-state fermentation using Saccharomyces cerevisiae on the cyanide content degradation of cassava leaves; and (ii) to optimize the independent variables for the minimum cyanide content level of cassava leaves by the application of response surface methodology (RSM). The various process parameters investigated for these purposes were sucrose concentration, urea concentration, moisture content, and fermentation time. The degradation of cyanide content was described by the quadratic model, which resulted in an excellent fit of the experimental data (p < 0.01). The statistical tests show that linear terms for sucrose concentration, urea concentration, moisture content and fermentation time had a significant effect on cyanide content (p < 0.01). Moreover, the interaction coefficients between sucrose concentration and fermentation time; urea concentration and moisture content; and nitrogen concentration and fermentation time were significant model terms (p < 0.05). A minimum cyanide content of 0.81 ppm was obtained at 1% (w/w) sucrose concentration, 0.5% (w/w) urea concentration, 60% (v/w) moisture content and with a fermentation time of 78 hours. The optimal level made a significant reduction in cyanide content of 97.96%, which is lower than the toxicity level suggested by the World Health Organization of 10 ppm.
Cassava is one of the most widespread starchy tuberous roots in Indonesia, being one of the typical plants used in the starch market. However, due to the high cyanide content (338.41 ppm), these roots become a poison if they are unsuitably processed. Therefore, a detoxification process is needed to reduce the cyanide level to the safe level for human consumption (10 ppm). This study was focused on (i) the investigation of the detoxification potential of fermentation with Lactobacillus plantarum (L. plantarum) on the cyanide level of wild cassava tubers (Manihot glaziovii) and (ii) the optimization of the fermentation time and bacteria cell number in the starter culture. The fermentation was performed for different periods of time (12, 24 and 36 h) and various initial bacteria cell number (7x10 10 , 7x10 11 , 1.05x10 12 , and 3.5x10 12 L. plantarum cells). The results showed a significant decrease of the cyanide level, 97 % of cyanide degradation being noticed after 36 h of fermentation for an initial bacterial cell number of 3.5x10 12 cells. Hence, the strong point of the study consists of a noteworthy reduction of the cyanide content in wild cassava in short periods, whereas the protein content was increased (from 1.5% to 3.5%) in Modified Cassava Flour (MOCAF).
The cassava plant is grown in tropical and subtropical countries, which represents, alongside with its by-products, an important source of food and feed. Hence, this plant has the capacity to promote the economic development of those countries and provide food security. However, cassava has some disadvantages due to the antinutrient compounds produced in its tissues. In addition, the cassava roots have a low protein content. Due to the economic and practical advantages, the solidstate fermentation (SSF) has been used as a cost-effective and efficient processing method to detoxify the cassava products and enrich them in nutrients. This chapter reviews the solid-state fermentation technique of cassava products for the production of valuable components for food and feed applications, microorganisms involved in this process, and key factors used to optimize the SSF process.
With the toxicity problems arising from the consumption of hydrogen cyanide (HCN), an acceptable method of processing edible leaves with low HCN level while maintaining maximum nutritional content remain a challenge. This data focuses on the extraction kinetics of cyanide in cassava leaves during the soaking process. Various process parameters conducted at 26 ± 2 °C were evaluated, such as contact times (1–20 h) between the leaves and solvent, as well as the water-to-leaves ratios (spanning a range of 10–50 mL/g). After ten h of extraction with water, all experiments resulted in less than 9.5 ppm of HCN, which is less than the toxicity level recommended by the World Health Organization (10 ppm). The mild approach resulted in protein loss from 36.01% to 23.10–25.38%. Water-to-leaves ratios of 10, 30 and 50 mL/g resulted in a calculated effective cyanide diffusion coefficient of 0.864 × 10 −13 , 1.39 × 10 −13 , and 1.61 × 10 −13 m 2 /s. The experimental data were also analyzed using empirical mathematical models to depict the leaching process. Accordingly, the data was predominantly fitted by Diffusion approach and Verma models with coefficients of determination (R 2 ) of 0.999.
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