Abstract
In Benguet, Philippines, efforts have been made to improve the production of high quality Arabica coffee beans (Coffea arabica). However, defects in coffee beans may still occur during post-harvest processing. Since defective coffee beans decrease the quality of coffee brews, they are commonly consumed in the municipality as beverage and are not sold commercially. In this study, the incidence of fungal and ochratoxin A contamination, in green and roasted immature and black defective coffee beans were investigated. Furthermore, the antioxidant properties of defective coffee beans were evaluated using a radical scavenging assay and metal chelating assay. It was found out that green coffee bean samples were contaminated with ochratoxigenic fungi and ochratoxin A. Roasting the green coffee bean samples decreased their total phenolic content, but increased their radical scavenging and metal chelating activities. The antioxidant activities, however, were statistically lower than standard antioxidants such as L-ascorbic acid, gallic acid and ethylene diamine tetraacetic acid (ρ<0.05). Ochratoxin A levels in defective green coffee beans also decreased after roasting. While phenolic compounds contribute to the antioxidant activities of the green coffee beans, the antioxidant activities of roasted coffee beans may be attributed to other antioxidant compounds formed during roasting. There is a need to further process contaminated defective coffee beans prior to utilization to isolate antioxidant compounds and remove ochratoxin A.
Highlights
Coffee is globally recognized as a popular beverage with well-documented in vitro antioxidant activities (Ramalakshmi et al, 2009; Liang and Kitts, 2014; Górnaś et al, 2016)
Our results reveal that the levels of ochratoxin A (OTA) in black defective green coffee beans agrees with the OTA level reported in the study of Taniwaki et al (2014) (25.7 μg*kg-1)
The radical scavenging activity exhibited by both non- This study shows that defatted extracts of defective green defective and defective coffee samples
Summary
Coffee is globally recognized as a popular beverage with well-documented in vitro antioxidant activities (Ramalakshmi et al, 2009; Liang and Kitts, 2014; Górnaś et al, 2016). In the Philippines, Benguet ranks third among the provinces in the Cordillera Administrative Region with the highest coffee production, with Arabica coffee variety grown in backyard or commercial coffee farms (Culliao and Barcelo, 2015). In an effort to minimize fungal contamination of coffee, wet processing is practiced by coffee growers in several areas of Benguet (Alvindia and Acda, 2010) and good agricultural practices are promoted by coffee farmers. The environmental condition in the province is characterized by low diurnal temperature and high humidity which may compromise efficient drying of parchment coffee. Fungal contamination of coffee especially during post-harvest processing is common. Fungal contamination can cause defects in coffee beans and may decrease the quality of coffee brew
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