Why Nigeria should promote stevia plants production – RMRDC boss

Stevia is a sweetener and sugar substitute extracted from the leaves of the plant species Stevia rebaudiana, a native of Brazil and Paraguay. Dr. Ibrahim Husaini Dogo, Director General of the Council for Raw Material Research and Research (RMRDC), in this interview explained why Nigeria should fully adopt its production for the production of bio-sugar. Excerpts:

RMRDC intends to go into the production of stevia, which I doubt, many people know a lot about it. Can you give us a vivid description of the plant and its growing potential in Nigeria?

Stevia rebaudiana is a zero-calorie natural sweetener that has recently been widely distributed in the food and pharmaceutical industry worldwide. This is a natural sweetener with high medicinal and commercial value.

Stevia is a subtropical perennial herb belonging to the family, an asteroid. It has annual, sublion, more or less pubescent stems with an extensive, fibrous and filiform root system. The cultivated stevia plant grows vigorously, giving a branchy shrub shrub appearance. Stevia is native to Paraguay and Brazil and is often referred to as sweet grass, horn leaf, honey yerba and lozenges. The leaf has been used for centuries as a sweetener to counter the bitter taste of various herbal remedies.

In 1964, this crop was first cultivated in Paraguay, and then presented in several countries. Currently, it is successfully developing in different conditions of cultivation and climatic conditions of the world. Stevia seeds remain viable for a limited period of time and have a very low level of germination due to their small size. Being a highly heterozygous type, there are also variations in plants grown from seeds. They do not produce plants with the true type, so a constant re-selection for the type is required on the plots of the maternal seed.

Stevia is mainly propagated by vegetative means, but this is a time consuming procedure. To increase productivity and profitability, careful selection of the plant is required.

Stevia prefers well-dried fertile sandy loam or loamy soil with a high content of organic matter. He prefers a lighter acidic neutral (pH 6-7) soil for better growth. This requires a constant supply of water, but excessive irrigation in water intake soils can cause stem rot diseases. This requires a partial shade on very hot and long sunny days.

Stevia fertilizer requirements are moderate and vary depending on the environment and soil type. The plant prefers low levels of nitrogen, but high levels of phosphorus and potassium. In average climatic conditions and soil type, 70 kg of nitrogen, 35 kg of phosphorus and 45 kg of potassium per hectare were recommended.

Why does the council intend to manufacture stevia when there are so many plant species in Nigeria that have yet to be developed?

This is a very brilliant question. It is true that in Nigeria there are more than 500 plant species. Much work has been done on plant biodiversity at the local level. It is also true that the industrial potential of some of them is not well understood. Let me say, however, that the global interest in stevia is due to its special attributes. Stevia is currently being promoted in most parts of the world for use in the production of bio-sugars. The World Health Organization (WHO) estimates that over the next few years, 20 percent of the sugar consumed in most countries will be replaced by bio-sugar. The emphasis is changed from sweeteners made from chemical ingredients, since they cannot control the incidence of diabetes, which is destroying the world.

Do you think it can be commercialized in a country like Nigeria?

Stevia can be commercialized in developing countries with its inherent value. It is currently commercially grown in China, Japan, Brazil, Canada, USA, UK, Spain, Belgium, Australia, South Korea, Thailand, Israel, and Taiwan. China and Japan are the world's largest producers and exporters of diterpene glycosides. Japan has approved the use of stevioside in many foods, including cereals, tea and soft drinks.

In India, stevia has been introduced in the last decade as a result of high demand due to its huge diabetic population. It has been successfully cultivated in many Indian states, such as Rajasthan, Maharashtra, Punjab, Kerala and Orissa. The high demand for natural sweeteners compared to artificials has led farmers in India to grow large-scale stevia.

In these countries, the cultivation and processing of stevia is rapidly developing into multimillion enterprises. If we move forward adequately, I am sure that a number of pharmaceutical companies will close. Currently, the National Agency for Food and Drug Administration (NAFDAC), a registered imported bio-sugar, is sold in many supermarkets in the country.

Considering the high level of losses after the harvest in Nigeria; which is between 30 and 70 percent a year, how do you intend to ensure that this initiative does not go the same way?

Stevia leaves are ready for the first harvest after four months of planting, and subsequent cleaning can be done every 3-4 months. On average, three to four commercial harvests per year can be obtained, depending on the type of land, variety and climatic conditions. Young actively growing areas of shoots and leaves have a high content of glycosides and more mature leaves, showing chlorosis, have a lower content of glycosides.

Shooting tips can also be trimmed with the leaves when harvesting because they contain the same amount of diterpene glycosides as the leaves. The total content of glycosides in the leaves begins to decrease with the onset of flowering, so harvesting should be done before the onset of flowering or immediately after the formation of flowering buds.

Drying is the most important post-harvest stevia activity. The board has developed various types of dryers. Some of them were commercially deployed. This is important because freshly harvested stevia leaves contain a high moisture content and deteriorate if they are not properly dried. Drying the leaves should be completed immediately after harvesting, placing the leaves on a screen or grid. You can also use the method of drying in the sun. This can be done in moderately warm conditions after about 12 hours. For quick drying in the sun requires good aeration with a low loading density. It can also be dried in a simple dryer, passing hot air just above room temperature. It was also reported that the quality of leaves dried at 50 ° C in a hot air dryer for six hours is better in terms of color, sweetness and nutrients. Dried leaves with a moisture content of three to five percent should be packed in sealed containers and stored in dry and cool places.

How do you plan to process leaves due to the low level of technology development in Nigeria?

Extraction of stevioglycosides from the leaves includes only the usual cleaning processes and procedures. This is somewhat similar to the extraction process used in sugar mills. Extraction of glycosides from stevia leaves includes extraction with water or a solvent, ion exchange purification, precipitation, filtration, crystallization, and drying. The extraction protocol involves dissolving the leaves in hot water or alcohol.

In addition, leaves can be treated with non-polar solvents, such as chloroform, to remove oil, lipids, chlorophyll, and other non-polar substances. It was found that methanol is the best solvent for the extraction of Rebaudioside-A from leaves in terms of the yield of components. It was also found that ethanol and aqueous acetone are suitable for the extraction of Rebaudioside-A, but the yield may be lower compared to methanol. The extracts were then clarified by salt precipitation or alkaline solutions, concentrated and redissolved in methanol to crystallize glycosides.

The usual steps in the extraction process are soaking the leaves in warm water to dissolve the glycosides, precipitating and filtering the resulting solution, concentrating by evaporation, ion exchange purification, spray drying and crystallization to obtain a white powder / crystals.

Today, most of the commercial processing of stevia leaves for the extraction of steviol glycosides is concentrated mainly in China and Japan, where the plants are located near cultivated stevia.

As a new initiative, the relevant authorities have approved stevia consumption products worldwide?

Yes; Over the past 50 years, many biological and toxicological studies have been carried out on stevil compounds of stevia. The European Food Science Committee (SCF) Scientific Committee evaluated the safety issues of this natural sweetener in 1985 and 1999 and raised questions about the lack of acceptable purity characteristics.

In 2004, the Joint FAO / WHO Expert Committee on Food Additives (JECFA) established preliminary purity specifications, which subsequently became permanent. JECFA established an acceptable daily intake (ADI) of 4 mg / kg body weight / day for purified steviol glycosides in 2008 and confirmed its use as a sweetener in food and beverages.

The plant and its extracts have also been used for several years as a sweetener in South America, Asia, Japan, China and in various countries of the European Union. In Brazil, Korea and Japan, stevia leaves, stevioside and highly purified extracts are officially used as low-calorie sweeteners.

Currently, in the US, leafy or extracted forms of stevia are used as a food additive.

How do you intend to ensure the success of this initiative, given that there are no stevia agronomists in Nigeria?

The Council works with Kong Associates Shaghai (China) Limited to promote the development of various plant varieties. The company introduced more than 100 improved castor seed varieties from China to the Agato region of Ghana for several local tests.

In November 2017, tests were completed, and Kong Associates selected the most adaptable varieties for the tropics to develop commercial castor seed plantations. In connection with the ongoing collaboration between RMRDC, Kong Associates and the Nigerian Association of Castors, Processors and Marketers (CPPMAN); Kong gave Nigeria a significant amount of seed for multiple tests in Nigeria in 2017.

Kong also promotes safflower and stevia in Ghana. The company agreed to provide us with improved stevi grades for multi-path testing in the country. He also plans to send stevia agronomists to the country for direct landing operations. The company is interested in buying leaves and farmers who participate in the program. This would guarantee product refinement.

Related