Banana and coffee composite flours: a second chance for industrial by-products

Diana Paola Porras Navia, PhD in  Food Engineering, and Carolina Franco Urbano, Master's student in Food Engineering, two of the project's researchers. Credit: Édgar Bejarano, Communications Office, Faculty of Engineering.

As a result of the practices derived from agricultural production in Colombia, a large percentage of the products that are grown are destined for other uses, such as animal feed, fertilizer or refining processes. This means a waste of the benefits that these products contain for the health of potential consumers. A research project proposes the creation of a flour made from plantain and coffee plantation residues, which could be translated into productive projects with great economic potential, especially for small producers.

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Banana and coffee by-products and their impact on the food sovereignty of smallholders

Although Colombia is a country characterized by its crop diversity, there is still insufficient infrastructure and studies to reduce the by-products that remain in the soil as a result of agricultural practices in large industries. As a result of this lag, many of these by-products, such as plantain and coffee (plantain rejects, plantain rachis and coffee pulp) are destined to activities that have a high negative impact in environmental terms or that do not allow taking full advantage of their nutritional qualities.

Aware of the potential that these have when thinking about the creation of a new product with great food value, the PhD in Food Engineering from the Universidad del Valle Diana Paola Navia Porras, the PhD in Fine Chemistry from the University of Cordoba, Spain, and professor and researcher at the School of Food Engineering of the Universidad del Valle, Laura Sofia Torres Valenzuela, the PhD in Agronomic Sciences in Biological Engineering from the Free University of Brussels, Belgium, professor and researcher at the School of Food Engineering of Universidad del Valle José Luis Plaza Dorado, together with food engineer and student of the Master's Degree in Food Engineering at Universidad del Valle, Carolina Franco Urbano, embarked on a research project aimed at using these by-products to create a precooked composite flour. 

This project, which is part of the "Orchids Program. Women in Science: Agents for Peace", is financed with resources from the Francisco José de Caldas National Fund for Science, Technology and Innovation. This initiative seeks to expand the participation of women in the field of science in the country, working with small producers on farms located in the municipality of Trujillo, Valle del Cauca, with the aim of promoting the development of innovative production chains and investment in infrastructure and technology, while helping to strengthen the food sovereignty of families living in this region. 

The by-products dilemma: the case of bananas and coffee

The purpose of the research project carried out by researchers Navia, Torres, Plaza and Franco was to obtain a precooked flour from the mixture of three flours obtained from the three raw materials evaluated (reject plantain, plantain rachis and coffee pulp), by means of an extrusion process. To achieve this, the researchers subjected the collected by-products to a prior disinfection process. Sodium hypochlorite was used for this purpose, at a concentration that was indicated to the small producers on the farms: 5 milliliters per 10 liters of water. The choice of hypochlorite and the indication responded to the fact that it is an affordable disinfectant on the market, which facilitates its use. 

This social component, which prioritizes the needs and economic constraints of these producers, was a key factor in the research. "Our methodology in the production of the flours was always thinking that they (small producers) could do something at some point, on their farms," says researcher Carolina Franco Urbano, adding that this purpose was also taken into account for the drying phase of the by-products. According to her, this process was intended to resemble solar drying conditions on the farms, which occurs at 45°C. 

Subsequently, a mix design was carried out to determine the optimum composition for the desired flour, taking into account nutritional components such as protein, fiber and carbohydrates, functional properties such as total phenolic compounds and antioxidant capacity, and technological properties such as extrusion feasibility. This analysis resulted in a composition of 36.36% coffee pulp flour, 32.94% reject plantain flour and 30.69% plantain rachis flour. 

After this, a milling and sieving process was carried out, by means of the extrusion method, which consists of applying high pressures and temperatures to a base matrix, which in this case was made up of flours. This method is traditionally used by the food industry in the production of corn extrudates (snacks), due to its economic advantages, and is based on the use of a worm screw through which the raw material passes at a high temperature, which is then milled. 

Benefits of blending these by-products

The process was characterized by the researchers and resulted in high levels of fiber, protein and carbohydrates, with 18.64%, 21.72% and 47.39%, respectively. Other values evaluated were total phenolic compounds and antioxidant capacity, water and oil absorption activity and capacity. 

This mixture also brought out unexpected goodness in the by-products used, which contributed to improve the quality of the resulting flour: "We thought that the (plantain) rachis would only provide fiber, but we were surprised to find that this is a nutritionally and functionally promising raw material for other uses. We found it interesting to see how the pulp, plantain and rachis complemented each other," says researcher Franco Urbano.

Although working with three by-products was a challenge, given that they do not share the same harvesting times and their characteristics require a different treatment for each case, the results obtained have opened the doors to think about other functions in addition to those that had been considered at the beginning of the project. "The project was initially focused on feeding chickens, but seeing the results we believe that not only can it be used in them, but it can also be used in feeding people," says professor and researcher Diana Paola Navia Porras, and adds that with this objective they expect to continue making analyses and studies.

Once the mixture has been characterized, the project is in a phase of evaluation of the bioavailability of the nutrients inside, which seeks to determine which of those can be absorbed by animals or humans, as well as the degradation capacity of the antinutrients - natural or synthetic compounds that hinder the absorption of nutrients - contained inside the mixture, coming from the by-products.

Impact on small producers

This research project, which has been carried out through the relationship with small producers, has been based on the principle of building knowledge from the traditions and knowledge of the communities. This principle has facilitated joint work from which both parties have benefited. "We have to respect their customs, their culture or what they are used to doing. Their knowledge. We don't impose, but show them solutions, and from that point of view they can access them," explains professor and researcher Diana Paola Navia Porras.

According to her, there are several aspects from which to consider the impact that this proposal could have on these communities. In the first place, there is the utilization of the by-products generated on the farms. Secondly, the possibility of obtaining an economic benefit from the creation of value-added products, such as these composite flours. And, thirdly, the great advantage that is related to the environmental care in these places, since by-products such as coffee pulp have a high organic load that, if not properly managed, can affect water sources and other ecosystems. 

Regarding the future of this composite flour, researcher Carolina Franco Urbano thinks that, currently, the conditions are in place for the entry of a new product like this one, which expands the offer for a part of the population increasingly aware of the benefits of certain compounds, which is in search of other alternatives. "Now the consumer is looking to get out of those gluten-containing flours, for example. We see that people are looking for something more natural, more of their own. The industry is looking to make this change, and these are precisely the raw materials that we see as promising, because they have functionalities such as antioxidant capacity, which are also being sought after. We believe that industrially this can be an answer," she says.

If interested in being in touch with the researchers or any further information about the project, please write the Faculty of Engineering Communications Office: comunicaingenieria@correounivalle.edu.co.