FROM AGRICULTURAL BY-PRODUCTS TO ‘THE CREAM OF THE CROP’ Mia Sutranina Hambali Indonesian Master’s degree student in Nutritional Science Università della Calabria
to 2012 report by FAO [3], 868 million people in the world (12.5% of the global population, or approximately one in eight), are estimated to be undernourished, with the vast majority (98%) of them, 852 million, live in developing countries, where the prevalence of undernourishment is at 14.9% of the population.
ABSTRACT: Cassava (Manihot esculenta) is mainly grown as a mono-culture crop in many developing countries for its tuber roots, which are rich of carbohydrates. The leaves are rich in protein but not normally consumed by most people. In Indonesia, the young foliage of cassava is harvested as by-products to be eaten after boiled. However, they usually end as waste. Being abundant and resistant in harsh environments, in times of famine, cassava could serve as the front-liner to provide food security, to fulfill the requirements of both carbohydrates and protein. There are many possible uses of cassava leaves. They could be processed as cassava leaf protein concentrate and then mixed as an enrichment in various healthy drinks. These drinks could be introduced at schools in many developing countries to nourish school-age children. Along with education, providing adequate nutrition is an investment that will pay-off eventually. Generally treated as agricultural by-products (or even waste), cassava leaves could have actually been ‘the cream of the crop’.
One of the major malnutrition problems is kwarshiorkor, a result of inadequate protein intake. Importing high-grade animal products could solve the problem but would cause economic strains in countries with low Purchasing Power Parity (PPP). In comparison to animal products, plant leaves also have vitamins, minerals, and essential amino acids and can be used as a supplement of protein (if consumed in adequate amounts) especially when it is hard to keep livestock or where fish protein is lacking [4]. Cassava (Manihot esculenta) serves as a major food staple in many developing countries, where it is cultivated as a monoculture crop. Cultivating cassava is economically beneficial as the yield is high and it grows well in harsh environments. Cassava is mainly grown for its tuber roots, which are rich in carbohydrates but poor in protein, and not for its leaves, which could actually be the cheapest, most abundant source of protein for human. A hectare of cassava farm could yield 4.60 tons of leaves on a dry matter basis [5]. In Indonesia, the young foliage of cassava is harvested as by-products to be eaten after boiled, but generally, cassava leaves end as waste.
Categories and Subject Descriptors [Food for Health]; [Food Security]
Keywords Cassava, Cassava Leaves, Protein, Cassava Leaf Protein, Food Security.
1. INTRODUCTION:
The aim of this study is to elaborate on the use of cassava leaves as a source of protein in human diet.
In 1798, Malthus predicted that food shortages would be inevitable as population could grow geometrically whereas food production could only grow arithmetically [1]. As the world population keeps increasing every year, people believe that the world does not produce enough to feed the whole population. However, Malthus’ concept did not take into account human capacity to increase food supply. In fact, being abundant but not distributed well, every year one-third of total global food production for human consumption (around 1.3 billion tons) ends as waste, as retrieved by FAO in 2011 [2].
2. DESCRIPTION With their 30-40% protein contents/dry weight, cassava leaves are adequate sources of essential amino acids, except for the low content of methionine [6]. Synthetic methionine could be supplemented to the cassava leaf protein extract, which leads to the large increase of Biological Value (BV) of cassava leaves [6]. Alternatively, instead of synthetic methionine, natural sources of methionine such as sesame could be safely used. Mixtures of
People live in a paradoxical situation where the world still faces malnutrition although food supply should be enough. According
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cassava leaves and sesame showed a higher Protein Efficiency Ratio (PER), compared to the PERs of each of them alone [7].
4. CONCLUDING REMARKS
3. PROCESSING, RESULTS, AND APPLICATION
After root harvest, instead of being wasted, cassava leaves could be turned into by-products, or, even better, they could be ‘the cream of the crop’, due to its high protein content. If we can use them to the utmost, why waste them?
a.
Cyanide reduction Despite the good nutritional values, the presence of cyanide is the limiting factor of the use of cassava leaves in human diet. Cyanide content varies from 20 to 80 mg HCN per 100 g fresh leaf weight, but there have been reported samples containing as low as 8 mg HCN/100 g [8]. Simple sun-drying makes it possible to lower cyanide levels in cassava leaves as this simple process eliminates almost 90% of the initial cyanide content [9]. In Indonesia, cassava leaves are consumed safely after having been boiled. These simple cyanide reducing processes would come into handy in many developing countries of the tropics.
b.
Cassava Leaf Protein Concentrate (LPC) The conventional method to obtain LPC involves thermic treatment to precipitate proteins [10]. Eventually, further research shows that cassava LPC obtained by ultrafiltration has advantages in nutritional quality (in terms of higher PER and lower content of cyanide) in comparison to that obtained by thermocoagulation (the conservative thermic treatment) [7].
c.
Application Cassava leaf protein concentrate could be added to fruit juices to improve its taste, colour, and public acceptability. This mix could be introduced as a lowcost nutritional supplement drink at schools in developing countries. School feeding is an excellent way to keep school-age children well nourished and at the same time prevent them from leaving school. Along with education, providing adequate nutrition is an investment that will pay-off eventually.
5. REFERENCES [1] Malthus, T.R. 1798. An Essay on the Principle of Population. London: J. Johnson, in St. Paul’s Church-yard. [2] FAO. 2011. Global Food Losses and Food Waste. [3] FAO. 2012. The State of Food Insecurity in the World. [4] Ghaly, A.E. and Alkoaik, F.N. 2010. Extraction of Protein from Common Plant Leaves for Use as Human Food. American Journal of Applied Sciences 7 (3): 331-342. [5] Ravindran, V. and Rajaguru, A.S.B. 1988. Effect of stem pruning on cassava root yield and leaf growth. Sri Lankan Journal of Agricultural Science 25(2): 32-37. [6] Eggum, O.L. 1970. The protein quality of Cassava leaves. British Journal of Nutrition 24: 761-769. [7] Castellanos, R., Altamirano, S.B. and Moretti, R.H. 1994. Nutritional characteristics of Cassava (Manihot esculenta Crantz) leaf protein concentrates obtained by ultrafiltration and acidic thermocoagulation. Plant Foods for Human Nutrition 45: 357363. [8] Ravindran V 1991 Preparation of cassava leaf products and their use as animal feed. In: Roots, tubers, plantains and bananas in animal feeding (Editors: D Machin and Solveig Nyvold). FAO Animal Production and Health Paper 95: 111-122. [9] Ravindran, V., Kornegay, E.T. and Rajaguru, A.S.B. 1987. Influence of processing methods and storage time on the cyanide potential of cassava leaf meal. Animal Feed Science and Technology 17: 227-234. [10] Pirie, N.W. 1971.Equipment and methods for extracting and separating protein. In: Pirie, N. W. (Ed.), Leaf Protein: its Agronomy, Preparation, Quality and Use. Oxford, UK: Blackwell, pp. 53-62.
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