Research note Physical characterization of non-defective and defective Arabica and Robusta coffees before and after roasting Juliana C.F. Mendonça, Adriana S. Franca * , Leandro S. Oliveira Programa de Pós-Graduação em Ciência de Alimentos/FAFAR/UFMG, Av. Antônio Carlos, 6623, 31270-901 Belo Horizonte, MG, Brazil article info Article history: Received 19 June 2008 Received in revised form 5 December 2008 Accepted 21 December 2008 Available online 31 December 2008 Keywords: Coffee Defective beans Physical attributes abstract The presence of defective coffee beans is known to depreciate the quality of coffee beverage consumed worldwide. These beans represent about 15–20% of the total coffee produced in Brazil and, although they are separated from the non-defective beans, they are still commercialized in the coffee trading market. Thus, it was the aim of this work to verify if physical characteristics provide an effective discrimination of defective and non-defective coffees of both Arabica and Robusta species, before and after roasting. The evaluated parameters were size (volume), density and color. The results obtained in the present study showed that, within a given coffee species, defective beans can be separated from non-defective ones by sieving, before roasting. In the case of Arabica coffees, size separation between non-defective and defective can also be accomplished after roasting. Prior to roasting, color separation will be effective for Robusta coffees, but ineffective for separation of non-defective, immature and light sour Arabica beans. Ó 2008 Elsevier Ltd. All rights reserved. 1. Introduction Defective coffee beans have recently been the subject of exten- sive research, given the negative aspects they impart to the quality of the roasted and ground coffee used for beverage preparation and consumption (Mazzafera, 1999; Franca et al., 2005a; Oliveira et al., 2006; Ramalakshmi et al., 2007; Vasconcelos et al., 2007; Mancha Agresti et al., 2008; Mendonça et al., 2008). The presence of defec- tive beans is a consequence of problems that occur during harvest- ing and pre-processing operations. The most important defects are black, sour or brown and immature beans. Both black and sour de- fects are associated with bean fermentation whereas immature beans come from immature fruits (Franca and Oliveira, 2008). According to Clarke (1987), black beans will impart a heavy flavor to the coffee beverage, sour beans will contribute to sour and oni- ony tastes, and immature beans will contribute to beverage astringency. Color sorting is the major procedure employed for separation of defective and non-defective coffee beans prior to roasting. In Brazil, manual sorting is usually employed for green coffee classification and electronic sorting is employed in farms and cooperatives of producers for the actual separation of defective beans (Franca and Oliveira, 2008). Unfortunately, the coffee beans rejected by the color separation machine are usually dumped on the Brazilian internal market, being used by the roasting industry in blends with good quality ones. These defective beans represent about 15–20% of the total production of coffee in Brazil (Oliveira et al., 2006). Given the need to propose alternative profitable uses for such defective beans in order to improve the quality of the coffee con- sumed internally in Brazil, recent studies have focused on physical and chemical characterization of defective beans in comparison to non-defective (good quality) ones. Even though color sorting is the procedure employed in the farms, cooperatives and industries for separation of defective beans, there are only a few literature data on color measurements for defective coffees (Franca et al., 2005a; Ramalakshmi et al., 2007). Furthermore, this separation procedure is not efficient, given that, in order make sure that such defects are effectively removed from a specific coffee lot, color sorting machines are usually set up to allow some non-defective coffees to be also re- moved if their color is similar to that of sour or immature beans. As a consequence of this, Arabica coffees that have been rejected by the color sorting machine usually present a high percentage of non- defective coffees (30–70%), as pointed out in studies employing ma- chine sorted Arabica coffees (Franca et al., 2005a; Vasconcelos et al., 2007; Mendonça et al., 2008). A detailed review and discussion of the published data on color evaluation for defective and non-defec- tive coffees is presented by Franca and Oliveira (2008). In view of the aforementioned, and the fact that there are still no reports on the use of physical attributes for separation of defec- tive beans after roasting, the objective of the present study was to present an evaluation of physical attributes of defective and non- defective coffee beans of both Arabica and Robusta species, before and after roasting. Furthermore, since the type classification sys- tem (by defects) is specific for Arabica coffees, and no literature 0260-8774/$ - see front matter Ó 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.jfoodeng.2008.12.023 * Corresponding author. Tel.: +55 31 34093512; fax: +55 31 34433783. E-mail addresses: drisfranca@gmail.com, adrianafranca@pesquisador.cnpq.br (A.S. Franca). Journal of Food Engineering 92 (2009) 474–479 Contents lists available at ScienceDirect Journal of Food Engineering journal homepage: www.elsevier.com/locate/jfoodeng