Fermetación de Cafe - Ingles
Graphical abstract
Coffee fermentation process to specialty coffee production.
Introduction
Coffee is one of the most important crops, and it is of enormous economic relevance (Bastian et al., 2021). According to the International Coffee Organization (2022), the Arabica coffee world production in 2020 was 105.262 thousand of 60 kg bags, and this showed an increase of 13.7 % compared to 2019 year. In the same period, the Brazilian Arabica coffee production was 60.292 thousand of 60 kg bags, and increase 26 %. From February/2021 to January/2022, 124.608.939 of 60 kg bags of coffee were exported to all destinations. Brazil has than one-third of global production and exportation being the biggest coffee producer and exporter, followed by Vietnam, Indonesia, and Colombia (Hall et al., 2022). Arabica coffee stands for 70 % global market and produces a beverage with a typical sweet aromatic (Batista, Souza, Batista, & Schwan, 2016, Hall et al., 2022).
In the coffee market, the term “specialty coffee” refers to a beverage that has a higher quality than the ones available for commodity prices, as well as a unique flavor and characteristics (Martinez et al., 2021). This quality of the coffee beverage is considered a consolidated criterion for reaching the markets that best pay for the product's added value. The Specialty Coffee Association (SCA) defined standardized methodologies to assist buyers and producers in evaluating the sensory quality of their products, especially for fair and more attractive trade (Cardoso, Agnoletti, Freitas, & Pinheiro, 2021). For the international market and coffee fermentation researchers, the method developed by SCA is the only one to define specialty coffee. The method consists of a sensory analysis released by certificated Q-graders, using roast coffee samples. In the cupping test, the samples are evaluated in relation to ten primary attributes of coffee: fragrance, flavor, aftertaste, acidity, body, uniformity, balance, sweetness, cleanliness, and score (SCA, 2018). For the SCA, the definition of beverage quality comes from specialty coffees characterized for not having any defect in the beverage, achieving at least 80 points in the rating scale for specialty coffees, and presenting differentiated quality and a high potential for aroma and taste expression (Cardoso, Agnoletti, Freitas, & Pinheiro, 2021). The specialty coffee production can be advantageous as it promotes a greater appreciation of coffee since the price of coffee is influenced by this classification – it is currently the main form of evaluation in the world market. According to Magalhães Júnior et al. (2021) specialty coffees can be commercialized for US$ 20/kg, while commodity coffee beans only US$ 2.5/kg. The growing demand for specialty coffee follows the increasing consumer interest in how coffee is brewed, as well as where, how and by whom the coffee was grown (European Market Potential for Speciality Coffee, 2020).
Seeking to meet the market that is looking for coffees with different sensory profiles, producers have been trying to develop new post-harvest practices, aiming to increase the grade of their coffees and sensory differentiation. Increases in final scores, even with small values, are reported as an improvement in quality. Furthermore, the final score is complementary to the flavor descriptive analysis, so it is not considered in isolation. Post-harvest processes have evolved over the years and the need to carry out the fermentation step in a controlled manner, mainly linked to the use of starter cultures, has already been pointed out as promising for flavor development, creation of volatile compounds, and product uniformity (Bressani et al., 2021, Brioschi Junior et al., 2021, Carvalho Neto et al., 2018; Elhalis et al., 2020a, Evangelista et al., 2014, Pereira et al., 2015, Martinez et al., 2021, de Pereira et al., 2020, Pereira et al., 2020, Ribeiro, Ribeiro et al., 2017). The fermentation has been carried out to develop new sensory profiles and increase the final score in coffees processed by different methods, aiming to achieve a better position in the market and a greater appreciation of the final product. In the literature there are already published patents on coffee fermentation. Most of them propose the development of equipment for use in induced fermentation of coffee fruits under different conditions of oxygen availability, temperature, agitation, and use of inoculating microorganisms (Cardoso et al., 2017, Bortoli & Wirth, 2022, Palini and Alves, 2022, Soccol et al., 2022, Soccol et al., 2018, Soccol et al., 2016).
Given this, the different ways of post-harvest processing including fermentative process application, show that the processing is no longer linked only to the old terms already known such as dry, semi-dry, and wet. This review aims to describe in detail the different protocols for conducting the coffee fermentation step. The new identification is focused on considering fermentation as a step influenced by four control variables: coffee treatment, oxygen availability, water addition, and starter cultures utilization. In addition, it is critical to discuss how those variables applied in an induced fermentation can influence microbial development and sensory specialty quality coffee based on SCA protocol. A better understanding and study of the influence of these variables allows us to improve the nomenclature of the coffee fermentation process and to promote better process control conditions and, consequently, greater reproducibility of the results.
Section snippets
Methodology for literature review
The literature review included scientific articles that presented case studies published in the last ten years (2012–2022). The literature review was conducted in the Science Direct and Springer databases, and patents in INPI (Brazilian National Institute of Industrial Property) and ESPACENET, with the structured set of keywords: “coffee fermentation”. After this primary search, 237 articles and 34 patents were compiled. In this review, only articles and patents which investigated the
Postharvest coffee processing
Coffee processing begins just after the harvesting of coffee cherries and the goal is to convert coffee cherries into green beans (Hameed et al., 2018, Wu et al., 2022). This process reduces fruit moisture and removes the protective outer coverings (husk, pulp, mucilage, and skin) around the pair of beans to make them more stable and suitable for storage, transportation, and roast process (Bastian et al., 2021, Hameed et al., 2018). The type of process employed depends on the area of
Coffee fermentation processing methods
It is known that coffee post-harvest processing is not developed in a sterile environment. In a lot of steps of the productive chain, several microorganisms are incorporated into coffee fruit, coming from the geographic region and manipulation (soil, air, equipment, people, and anything else that make physical contact with the fruits). The microbiota associated with the environmental conditions and the process control at the farm might or might not produce coffee with high-quality
Discussion
In recent years, coffee research has been based on mapping microorganisms, compounds produced during the coffee fermentation process and evaluating the effect of fermentation conditions on the physical–chemical composition of coffee and its sensorial characteristics. The researches aim to develop quality coffees that satisfy the global demand for specialty beverages with different sensory profiles. The sensory evaluation system proposed by SCA has been used worldwide to evaluate and classify
Conclusion
Important technological advances are being tested in coffee fermentation processes, but due to the complexity of coffee variety and the relationship with soil and climate characteristics, microbiota, and fermentation process conditions based on coffee treatment, oxygen availability, water addition, and starter cultures utilization, much remains to be explored. This review has contributed to the understanding of the several possibilities now available for coffee fermentation, not only the
Declaration of Competing Interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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