Working with yeasts seeks to improve the quality of the coffee drink

In order to get a coffee drink with good features, a doctoral student at the University of Lavras (UFLA), Suzana Reis Evangelista, developed a research project to evaluate the use of beneficial microorganisms for fermentation (yeasts), selected to improve the quality of natural coffee drink, obtained by dry process. This method consists of processing the freshly picked without being husked, that is, keeping the fruit with its structures until it reaches the ideal moisture to be stored in coconut and then be processed.
In recognition, the experience - which was conducted in the Department of Biology at the University - won the prize for the best work of the plenary Coffee and Biodiversity, the International Symposium on Biodiversity held earlier this month in UFLA.
The research had the guidance of the Professor of the UFLA Department of Biology, Rosane Freitas Schwan, who highlighted the importance of the work done. "Initiatives taken by research at this level make a difference, show that it is possible to add value to coffee and provide consumers a differentiated product, superior quality and consequently with higher market value" said the teacher.
Already Suzana Reis Evangelista, author of the study revealed that the main objective is to bring the results of the experiment to the field, which would benefit the producer. "The expectation is that the work can bring benefits to the Brazilian coffee, which can reach the producer. With better quality coffee, the market responds with best price. We hope the work can help farmers", she said.
In the work we used three yeasts harvested from the coffee fruits of species Saccharomyces cerevisiae, Candida parapsilosis and Pichia guilliermondii, which were sprayed on the cherries washed and unwashed before they initiate the process of fermentation, and thereafter coffee was conducted in the pateo taking care for a good fermentation/drying. One of the coffees received no treatment, for comparison with the samples that were treated with the yeast. It’s the control sample.
When the coffee has reached 11% moisture content samples were collected and evaluated and the persistence of yeasts producing organic acids and volatile compounds during the process of fermentation/drying. Once received, it was roasted and ground coffee was subjected to sensory analysis (cup tasting) methodology for TDS (Temporal Dominance Sensations), a technique that allows to evaluate differences between samples during the test.
Ending up tests showed that the yeasts persisted until the end of the process and competed with bacteria and fungi that harm the coffee beverage. The treated samples were not producing propionic and butyric acids (harmful) in concentrations that affect the quality of the drink.
Coffee subjected to treatments with yeast had nice flavour and more pronounced in relation to coffee untreated, indicating an increase in sensory quality. The samples that were not washed after harvest were not as pleasant in sensation compared to fruits that were washed, suggesting that the washing of fruits before proceeding to the fermentation/drying positively influences the quality of the drink.
There were also differences in the effect of yeast. The caramel and herbs flavours were more evident in the samples washed and treated with Candida parapsilosis while in the samples not washed the best effect was observed in the beverage with Saccharomyces cerevisiae.
This type of study is important because the coffee production, especially for the manufacturing sector, is going through a difficult time because of the low prices of the bag of coffee at the market. In this situation, all resources within reach of the producer and the sectors linked to the coffee chain must be used in order to mitigate the negative impacts of the crisis and tackle this context the quality of the coffee drink is being valued. It is known that a product with superior drink is worth more in relation to another with inferior drink, even though both have the same rating as the type.
CNPq, FAPEMIG and CAPES, development agencies for scientific research, supported the project.
Source: Revista Cafeicultura