Research
Technique developed for a doctoral thesis makes better use of food, which can be frozen and formatted
Cassava on a stick
Manuel Alves Filho
PThe main source of calories for approximately 500 million people in the world, cassava is still a food little studied in Brazil and, therefore, practically unexploited industrially. A technology developed for Shirley Aparecida Garcia Berbari's doctoral thesis, recently defended at the Faculty of Food Engineering (FEA) at Unicamp, brings a new perspective to the use of this root, which has Brazil as its second largest producer in the world (24.354 millions of tons). After four years of research, Shirley obtained shaped, pre-fried and frozen sticks made from cassava pulp and flour, which have several advantages over conventional products sold on the market. The main one is the homogeneity of shape and texture.
According to the researcher, conventional cassava sticks are the result of a very simple process, which only involves peeling, cutting, cooking and freezing the root. According to her, this preparation is similar to that applied to potatoes, whose characteristics are very different from those of cassava. “This creates some problems, as both the cooking and the shape of the sticks are not uniform,” says Shirley, who has a degree in food engineering. To solve this problem, she developed an innovative technique: after peeling and cooking, the cassava is crushed, gaining the consistency of dough. This pulp then goes to a machine where it is transformed into structured sticks.
The last two steps are pre-frying and freezing. At the end of the process designed by Shirley, sticks that are homogeneous in shape and texture are obtained. The researcher, however, went further and resolved another obstacle involving the industrialization of cassava. As it is a highly perishable food, the root must be processed within a maximum period of 48 hours after harvest. The alternative was to transform the cooked pulp into two types of flour with different granulations. Mixed, they become the raw material for the production of pre-fried and frozen sticks.
To arrive at the composition of the flours, which can be stored for more than a year, the researcher followed the previous process. The difference is that the cooked cassava mass is dehydrated and ground. To obtain the paste that will generate the sticks again, simply add water and oil, the proportions of which are defined through a specific calculation. Then, the process resumes with formatting, pre-frying and freezing. “This technology is dominated by other countries, but only in relation to potatoes”, explains the author of the thesis.
An additional advantage provided by the technique developed by Shirley is related to performance. In the conventional process of producing pre-fried and frozen cassava sticks, utilization is around 45%. In relation to the structured product, this index rises to 65%. To complete her research, the food engineer used the pilot plants at the Institute of Food Technology (Ital). “This was important, as it was proven that the entire process can be perfectly reproduced in an industry.”
The structured cassava sticks were also the subject of an acceptance test (tasting) with Ital employees and scientists. According to Shirley, the product was unanimously approved. “Structured sticks also allow for some variations, such as adding flavors. Furthermore, they can be produced in the shape of a star and animal, which will encourage consumption by children”, adds the researcher. According to her, her objective, which is to disseminate and give greater status to cassava, is close to gaining two important impulses.
A national group and a Bolivian group have already shown interest in acquiring the technology. “The better use of cassava by the Brazilian industry will certainly bring financial and social gains to the country. It is a crop with great productivity and which practically does not require the use of agricultural pesticides. Furthermore, it does well in poor soils and does not require more elaborate management. Not to mention that the root is the largest source of calories and guarantees the subsistence of a large number of families in the Northeast”, recalls Shirley.
From root to freezer
1 The cassava is peeled and cooked
2 Crushing, 2nd phase of the process
3 Start of preparing the dough
4 Pre-frying process
5 The already formatted sticks
6 Freezing food
A stronger orthopedic cement
A technology recently developed by a graduate student at Unicamp promises to significantly improve the results of bone remodeling and reconstruction surgeries. Result of the doctoral thesis defended by Luís Alberto dos Santos at the Faculty of Mechanical Engineering (FEM), fiber-reinforced calcium phosphate orthopedic cement presents a series of advantages in relation to materials in use on the market. The main one is the high resistance to impacts, very close to that of human bones. Thanks to this characteristic, the new material considerably increases its field of application, currently restricted to dental, cranio-maxillofacial interventions and filling cystic and tumor cavities.
According to Santos, bone remodeling and reconstruction surgeries currently use materials such as calcium phosphate-based ceramics and calcium phosphate cement. The main characteristic of the first is biocompatibility, which favors bone growth to the location where it is located. However, as it is found in the form of blocks and granules, ceramic, also known as “synthetic bone”, does not allow for modeling, thus making it difficult to adapt to the implant site. Conventional calcium phosphate cement does not impose this limitation, as it is a paste that can be modeled, obtained by mixing calcium phosphate powder with an aqueous solution.
Despite having this advantage over calcium phosphate ceramic and being absorbable, giving rise to new bone tissue, conventional calcium phosphate cement has a low mechanical resistance, which is about one fifth of that of cortical bone (bone dense) human. The challenge Santos successfully faced was precisely to increase the mechanical resistance and tenacity of this material, ensuring that it maintained its positive properties. After four years of research, guided by professor Celso Arruda, from FEM, and professor Anselmo Boschi, from the Federal University of São Carlos, he achieved these objectives through the incorporation of reinforcing fibers. “Within the cement matrix, the fiber contributes to increasing the body’s ability to withstand efforts. The load is transferred through the matrix to the fiber, increasing impact resistance”, explains the thesis author.
The fibers used to reinforce calcium phosphate cement are obtained from national and international suppliers. They are commercial and everyday materials, such as nylon and polypropylene microfibers, used to make clothes, and carbon fibers, used in the aeronautical industry. Santos states that his project achieved the combination of three distinct characteristics: the bioactivity of the ceramic, the malleability of the cement and, of course, the high mechanical properties. “The project also enabled the development of technology to obtain calcium phosphate cement formulations – a technique dominated by a few countries –, from national raw materials. This will allow, in the future, a reduction in consumer prices, since a gram of imported material costs around US$200,00”, says the researcher.
According to Santos, new calcium phosphate cement compositions have been developed and are in the process of being patented by Unicamp and researchers. They have better mechanical properties, withstanding impacts greater than those of human bones. “These more resistant compositions can be used beyond locations with low load loads. They also apply to orthopedics and neurosurgery, as an alternative for the consolidation of multiple fractures of long bones, fixation of cemented joint prostheses and replacement of intervertebral discs”, he highlights.
The new materials, adds the author of the thesis, were tested on animals, in partnership with the Faculty of Agricultural and Veterinary Sciences of Jaboticabal, from Unesp, and showed excellent biocompatibility. “Currently, we are making contact with companies specialized in the field of orthopedics and dentistry, aiming to transfer the technologies developed”, concludes Santos. (MAF)
