Dados do Trabalho

Título

XYLOOLIGOSACCHARIDES FROM COFFEE (COFFEA ARABICA) RESIDUAL HULLS BY HYDROTHERMAL PROCESSING

Introdução

During the wet processing of coffee, only 60% of the bean is used, generating agroindustrial waste. An alternative to valorize them is to obtain xylooligosaccharides (XOS), which are considered prebiotics. Hydrothermal processing (HTP) is a sustainable technique using water as a solvent at high temperatures and pressures. The effect of HTP on the production of XOS from residual coffee husk free of extractives was evaluated, considering time and citric acid content.

Material e Métodos

HTP was processed in a 1 L Parr reactor, performing four treatments: T1, 40 g sample / 300 mL water for 30 min, + 100 mL water added and treated for another 30 min. T2, 40 g of sample / 800 mL for 60 minutes; at T3, 40 g of sample / 400 mL; at T4, 40 g of sample / 400 mL with 7% citric acid. All treatments were carried out at 180 °C, with agitation at 120 rpm. The concentration of sugars and XOS in the liquid fraction was analyzed by HPLC.
Liquid fraction (T3 and T4) was subjected to a purification system with a nitrogen line, pH was adjusted to 6.5 to perform ultrafiltration at 25 bar and 500 rpm using a 10 kDa membrane. The retained fraction passed through diafiltration under the same ultrafiltration conditions. The fractions permeated in ultrafiltration and diafiltration were mixed, pH adjusted to 4.5 and subjected to nanofiltration at 30 bar, 300 rpm using a 150 Da.

Resultados e Discussão

In the biomass, 15% of hemicellulose and 20% of cellulose were quantified. The xylose content was higher when citric acid was used (T4, -16 g/kg). The xylotriose content (14 g/kg) was higher in T3 and lower in T4; xylotriose and xylotetraose were detected only in the samples without citric acid. Membrane filtration was able to gradually concentrate XOS, especially in samples with citric acid in the medium.

Conclusão

These results indicate that XOS can be obtained from coffee waste, but further optimization of the process is needed.