Optimization of the fermentation time and bacteria cell concentration in the starter culture for cyanide acid removal from wild cassava (Manihot glaziovii)

Mohamed Hawashi,Tika Surya Ningsih,Sekar Bias Tri Cahyani,Kuswandi Tri Widjaja,Setiyo Gunawan,A.C Kumoro,A.W Lothongkum,M.A Hussain,L Yung,M.T Phong,P.T.S Nam,Hadiyanto Hadiyanto,S.A Roces,W.R.W Daud,X Rong

doi:10.1051/matecconf/201815601004

Abstract

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 (7x1010, 7x1011, 1.05x1012, and 3.5x1012 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 3.5x1012 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).

Highlights

Due to its high content in starch, one of the key food sources for humans, cassava (Manihot esculenta) is a raw material to prepare different food products, along with rice, sago, and corn
The cyanide acid content of fresh cassava was 338.41 ppm. These results clearly shows that the cassava roots used for this investigation are promising raw materials for starch production but the high content of the cyanide limits its exploitation
Our study shows that it is feasible to regulate the ratio between amylose and amylopectine in starch by controlling the concentration of the L. plantarum cells in the starter culture

Summary

Introduction

Due to its high content in starch, one of the key food sources for humans, cassava (Manihot esculenta) is a raw material to prepare different food products, along with rice, sago, and corn. Cassava has high productivity, it is easy to cultivate and can provide a good source of food for a vast majority of the Indonesian population and can increase national food security of Indonesia. The analysis of 45 Indonesian cultivars of cassava roots for cyanogenic potential (CP) showed that CP content usually ranges from 17.8 to 233.2 ppm [3].The wild cassava roots contain high content of hydrocyanic acid (HCN) ranges from 183.2357.2 mg/kg on dry matter basis (DM) [4]. Amylose has a strong effect on starch, while amylopectin provides crisp effects in food [7].The utilization of wild cassava root as such for food purposes has few drawbacks, because it contains high toxic cyanogenic glucosides compounds (93% linamarin and 7% lotaustralin) [8].

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Conclusion