The influence of high-temperature heating on composition and thermo-oxidative stability of the oil extracted from Arabica coffee beans.

The aim of the present study was to establish the influence of high-temperature heating on the composition and thermal behavior of coffee oils obtained from Arabica green and roasted coffee beans, respectively. Morphological studies performed using scanning electron microscopy revealed the oil bodies uniformly distributed within the cells in both types of coffee beans analyzed. The obtained oils have a fatty acid composition rich in linoleic acid, palmitic acid, oleic acid, stearic acid, arachidic acid and linolenic acid. The total content of saturated fatty acids of investigated oils was 49.38 and 46.55%, the others being unsaturated fatty acids. The thermal behavior and thermo-oxidative stability of coffee oils extracted from green coffee beans and roasted coffee beans, the coffee oil high-temperature heated up to 200 °C, were investigated using simultaneous thermal analysis TG/DTG/DTA, in an oxidizing atmosphere. The data obtained for the analyzed samples depend mainly on the nature and compositions of fatty acids, and to a lesser extent on the roasting process of the coffee beans and the high-temperature heating process of the extracted oil. The chromatographic and TG/DTG/DTA data suggest that Arabica coffee oil has great potential for use in technological processes which require high-temperature heating (e.g. food industry or pastries)

TG and DTG/DTA profiles for GCO.

<p>TG and DTG/DTA profiles for GCO.</p

TG/DTG decomposition data of the coffee oils samples.

<p>TG/DTG decomposition data of the coffee oils samples.</p

TG+DTG/DTA curves for HRCO.

<p>TG+DTG/DTA curves for HRCO.</p

TG+DTG/DTA curves for HGCO.

<p>TG+DTG/DTA curves for HGCO.</p

Fatty acids composition (%) of the investigated coffee oils (green coffee oil, GCO; roasted coffee oil, RCO; heated green coffee oil, HGCO; heated roasted coffee oil, HRCO).

<p>Fatty acids composition (%) of the investigated coffee oils (green coffee oil, GCO; roasted coffee oil, RCO; heated green coffee oil, HGCO; heated roasted coffee oil, HRCO).</p

Structure of the coffee beans revealed by scanning electron microscopy: For green: (A), (C), (E) and roasted coffee beans: (B), (D), (F), at 5 kV and different magnifications: 500x for (A), (B), 1000x for (C), (D), and 2000x for (E), (F).

<p>Structure of the coffee beans revealed by scanning electron microscopy: For green: (A), (C), (E) and roasted coffee beans: (B), (D), (F), at 5 kV and different magnifications: 500x for (A), (B), 1000x for (C), (D), and 2000x for (E), (F).</p