A comparative study of chemical attributes and levels of amines in defective green and roasted coffee beans Anna Luiza S. Vasconcelos a , Adriana S. Franca a, * , Maria Beatriz A. Glo ´ria b , Juliana C.F. Mendonc ¸a a a Nu ´ cleo de Pesquisa e Desenvolvimento em Cafe ´, DEQ/UFMG, R. Espı ´rito Santo, 6° Andar, 30160-030 Belo Horizonte, MG, Brazil b Departamento de Alimentos, FAFAR/UFMG, Av. Anto ˆnio Carlos, 6623, 31270-901 Belo Horizonte, MG, Brazil Received 13 June 2005; accepted 4 December 2005 Abstract Differences in chemical attributes (proximate composition, water activity, sucrose, acidity and pH levels) and amine levels between defective and healthy coffee beans were studied. Before roasting, significant differences (p < 0.05) were observed for the ash contents of the coffee samples, with the highest values found for black beans. Moisture content was higher for non-defective beans in comparison to defective beans. Non-defective coffee beans had higher lipids contents than both sour and black beans. There were no significant dif- ferences (p > 0.05) for protein levels between defective and non-defective beans. After roasting, protein levels remained constant, there was a small decrease in ash contents and a slight increase in oil contents of black and sour beans. Both black and sour beans had higher acidity levels than immature and non-defective beans. Acidity levels decreased after roasting. Water activity levels also decreased with roasting, with slightly higher levels for defective beans in comparison to non-defective ones. Sucrose levels were much higher in non- defective beans, and the lowest values were in black beans, prior to roasting. After roasting, only traces of sucrose were found. Total amine levels were much lower for black beans, in comparison to the other coffee samples. Putrescine was the prevailing amine in all sam- ples. Histamine was only detected in the defective coffee samples. Small amounts of serotonin, cadaverine and tryptamine were found in some of the samples. After roasting to a light degree, only traces of serotonin were detected and no amines were detected after roasting to medium and dark degrees. Ó 2006 Elsevier Ltd. All rights reserved. Keywords: Coffee; Defective beans; Chemical composition; Amines; Roasting 1. Introduction Coffee quality is evaluated according to a wide variety of criteria, including bean size, colour, shape, roast potential, processing method, crop year, flavour or cup quality and presence of defective beans (Banks, McFadden, & Atkin- son, 1999; Franca, Oliveira, Mendonc ¸a, & Silva, 2005). Among these, flavour is the main and most important cri- terion, which is directly affected by the presence of defective coffee beans. The presence of defective beans is usually a consequence of problems that occur during harvesting and pre-process- ing operations. The most important types of defects are black, sour or brown, immature, bored or insect-damaged, and broken beans. Both black and sour defects are associ- ated with bean fermentation and have been reported as quite important in downgrading coffee flavour (Clarke, 1987). Immature beans, those that come from immature fruits, contribute to beverage astringency. Even though defects are known to negatively affect coffee flavour, the number of defects alone cannot be used to accurately pre- dict flavour quality (Smith, 1985). Such defective beans are usually present in the coffee produced in Brazil, due to the strip-picking harvesting and processing practices adopted 0308-8146/$ - see front matter Ó 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.foodchem.2005.12.049 * Corresponding author. Tel.: +55 31 32381777; fax: +55 31 32381789. E-mail address: franca@deq.ufmg.br (A.S. Franca). www.elsevier.com/locate/foodchem Food Chemistry 101 (2007) 26–32 Food Chemistry