Evaluation of Cyanide Levels in Two Cassava Varieties (<i>Mariwa</i> and <i>Nyakatanegi</i>) Grown in Bar-agulu, Siaya County, Kenya

Abstract

Mannihot esculenta Crantz (Cassava) is the second highest producer of carbohydrates after sugarcane.However, some varieties have high levels of cyanogenic glycosides and therefore are potentially toxic for human consumption. Nyakatanegi is one of the local varieties cultivated in Bar-agulu village in Siaya County (Kenya) and has been severally in the recent past reported to cause fatal cyanide toxicity. The other variety which is rarely associated with cassava poisoning is Mariwa. The objective of the current study was to determine cyanide levels in the two cassava varieties (Mariwa and Nyakatanegi) which are locally cultivated in Siaya County. The study was based on three laboratory assays: the picrate paper, picrate in solution and titration. Whole root cassava tubers were collected from a farmer in Bar-agulu village, Siaya County, packaged separately and transported to Mount Kenya University Pharmaceutical Chemistry Laboratory for analysis. Voucher specimens were authenticated in the cassava laboratories at Jomo Kenyatta University of Agriculture and Technology. It was observed that all the cortex samples of Nyakatanegi variety had the highest concentrations of cyanide giving 400 ppm for the picrate paper assay, 14.10 mg/Kg for the picrate in solution and 63 mg/Kg for the titration assays. On the other hand, the cortex samples of Mariwa reported cyanide concentrations of 30 ppm, 11.20 mg/Kg and 27.20 mg/Kg for the picrate paper, picrate in solution and titration assays respectively. The results showed higher amounts of cyanide in the tested cassava varieties than the WHO recommended levels (10 mg/Kg) especially the Nyakatanegi variety. Based on these results, sensitization campaigns are necessary to minimize cases of cyanide poisoning following cassava consumption.

Physicochemical composition of different parts of cassava (Manihot esculenta Crantz) plant

“…Cyanide levels of the samples were determined using a picrate in solution method (Moriasi et al, 2017). In 5 mL of distilled water, 3 g of each part of the samples were dissolved.…”

Cassava flour production by small scale processors, its quality and economic feasibility

“…An economic feasibility analysis of cassava flour production (cassava flour mass balance, production cost, revenue, and benefit) was conducted by direct observation and data collection during flour processing operations. The laboratory analysis for chemical composition of fresh cassava root and flour included the moisture and ash contents using the gravimetry method (Elnovriza et al, 2019), fat content using the direct extraction method/Soxhlet (Elnovriza et al, 2019), protein content following the micro-Kjeldhal method (Maehre et al, 2018), dry matter content (Misganaw & Bayou, 2020), starch and amylose contents (Ginting & Noerwijati, 2008), HCN content using the argentometry method (Gervason et al, 2017), and titratable acidity (Matela et al, 2019). The physical properties of the fresh root and flour included the Hunter color (L*, a*, and b*) of a cross section of the middle of the root (1 cm-thick) using a color reader (Minolta CR-200b) (Ginting et al, 2015), and the flour whiteness using a Kett Whiteness Tester with BaSO 4 as a standard (100%) (Seveline et al, 2020).…”

Effects of Cassava Leaves Detoxification Processes on the Physicochemical and Sensory Qualities of &lt;i&gt;Saka Saka&lt;/i&gt;

“…The cyanides were determined by the titrimetric method [17]. For this purpose, a treated or untreated (control) sample of 20 g of shredded material was transferred to a flask and mixed with 200 ml of distilled water.…”