Evaluation of different processing methods to reduce the cyanogenic potential of cassava leaves
- Publikations-Art
- Poster
- Autoren
- Latif, S; Zimmermann, S; Müller, J
- Erscheinungsjahr
- 2015
- Veröffentlicht in
- Book of Abstracts
- Seite (von - bis)
- 126
- Tagungsname
- ELLS 2015
- Tagungsort
- Prague
- Tagungsdatum
- 13 - 14 November, 2015
- Schlagworte
- Cassava leaves, Cyanogenic potential, detoxification, nutrients, Picrate method
Cassava leaves are a valuable food source for human nutrition in tropical and subtropical countries however, they contain high amounts of toxic cyanogenic glucosides. Traditional processing methods for cassava leaves involve pounding followed by boiling for 1 hour or longer, which considerably reduces the nutrient content. In the present study, four different processing methods were investigated to reduce the cyanide content of cassava leaves. Total cyanide content of fresh and treated samples was determined by the semi-quantitative picrate method which is based on a color reaction of HCN with alkaline picrate and subsequent spectrophotometric measurement. A calibration curve was obtained using a standard solution of linamarin, the main cyanogenic glucoside in cassava leaves.
Fresh leaves were ground and subjected to microwave (800 W, 78 oC, 20 seconds), ultrasonic (35 kHz, 500 W, 55 oC, 15 minutes), enzymatic (8% Multifect® GC extra enzyme of dried leaves basis, pH 5, 55 oC, 4 hours) and sodium bicarbonate (2% of fresh leaves basis, 55 oC, 6 hours) treatment. Microwave, ultrasonic, enzymatic and sodium bicarbonate treatment reduced the cyanogenic potential by 63.6, 84.3, 82.1 and 93.3 %, while the cyanogenic potential reduction in the respective controls was 59.5, 84.0, 79.0 and 89.6 %. Highest reduction was achieved with the sodium bicarbonate treatment, which enhances detoxification probably due to an increase of pH and softening of the plant tissue. The long incubation period may also be a factor for detoxification. However, no method was able to detoxify the leaves to a level < 10 ppm, which is the safe HCN level recommended by the FAO.
Sodium bicarbonate is a simple and mild treatment which can be applied in households in developing countries. In our future study, the sodium bicarbonate processing parameters i.e. time and temperature will be further optimized to detoxify cassava leaves.