Effect of Roasting Levels and Drying Process of Coffea canephora on the Quality of Bioactive Compounds and Cytotoxicity

Abstract

Coffee is a popular drink consumed all over the world. Besides its long-recognized stimulant effect, it has important nutritional and health effects. However, the type of bean processing modifies the composition of brewed coffee and possibly its bioactivity. In this study, extracts obtained from green and roasted beans of Coffea canephora (Coffea canephora var. robusta) were submitted to spray- or freeze-drying and were tested for antiproliferative activity, using MTT assay, and their influence on the cell cycle and apoptosis by flow cytometry analysis. Moreover, colors and nutrient contents were measured to identify the changes due to the roasting process. The results obtained showed that extracts from green and light roasted beans exhibited strong bioactive capacity. Coffee extracts promoted a decrease in cell viability, modulated cell cycle and induced apoptosis in human prostate carcinoma cell line (DU-145). The level of roasting reduced this property, but the type of drying did not in all cases.

Keywords: Robusta; cancer; chlorogenic acids; green coffee; roast coffee.

Figure 1

Antioxidant activity potential according to DPPH assay, Trolox Equivalent Antioxidant Capacity (ABTS/TEAC), Ferric Reducing Ability (FRAP) and Oxygen radical absorbance capacity (ORAC) analyses of freeze-dried (A) and spray-dried (B) coffee extracts. Different letters in the same analysis mean that samples are different (p < 0.05) and same letters indicate the samples are the same (p > 0.05). Abbreviations: GF—green freeze-dried, LF—light roasted freeze-dried, MF—medium roasted freeze-dried, DF—dark roasted freeze-dried, GS—green spray-dried, LS—light roasted spray-dried, MS—medium roasted spray-dried, DS—dark roasted spray-dried.

Figure 2

Caffeic and chlorogenic acids contents in the soluble extracts of green, light roasted, medium roasted and dark roasted Robusta coffee, submitted to freeze-drying and spray-drying. Different letters in the same analysis mean that samples are different (p < 0.05) and same letters indicate the samples are the same (p > 0.05). Abbreviations: GF—green freeze-dried, LF—light roasted freeze-dried, MF—medium roasted freeze-dried, DF—dark roasted freeze-dried, GS—green spray-dried, LS—light roasted spray-dried, MS—medium roasted spray-dried, DS—dark roasted spray-dried.

Figure 3

Percentage inhibition in comparison with control of viability of prostate tumor cells (DU-145) by the MTT method, after 24 h of treatment with freeze-dried (A) and spray-dried (B) aqueous coffee extracts at concentrations from 25 μg/mL to 5000 μg/mL. Photos of wells with concentrations of control, 2500 and 5000 μg/mL (C). Abbreviations: GF—green freeze-dried, LF—light roasted freeze-dried, MF—medium roasted freeze-dried, DF—dark roasted freeze-dried, GS—green spray-dried, LS—light roasted spray-dried, MS—medium roasted spray-dried, DS—dark roasted spray-dried.

Figure 4

Effect of coffee extracts on rate of apoptosis in DU-145 cells after 24 h after incubation. Flow cytometry analysis of coffee extracts are illustrated in (A). (B) Relative increase rate of apoptotic cells of DU-145 treated with freeze-dried and spray-dried coffee extracts after 24 h of treatment. Relative comparison between untreated cells (CT) and cells incubated with coffee extracts. Means significant difference with different letters (p < 0.05). Abbreviations: GF—green freeze-dried, LF—light roasted freeze-dried, MF—medium roasted freeze-dried, DF—dark roasted freeze-dried, GS—green spray-dried, LS—light roasted spray-dried, MS—medium roasted spray-dried, DS—dark roasted spray-dried.

Figure 5

Beans and ground coffee (unroasted or with different levels of roasting).