Taguchi method to improve the production of sugar-rich hydrolysate from non-delipidated spent coffee grounds, and subsequent recovery of lipids and bioactive compounds

ABSTRACT

The direct hydrolysis of non-delipidated SCG was investigated in this study to assess the potential of the direct utilization of wet SCG and recovery of the available lipids. An optimum sugar yield was achieved using 4% v/v sulfuric acid at an SSR of 8 mL/g for a hydrolysis time of 3 to 4 hours at 95 °C. A sugar recovery of 81 to 98% of the available sugars was achieved. Hydrolysates contain ∼40 g/L of reducing sugars and 4.7 g/L of protein, while inhibitor concentrations were found to be below inhibitory limits. Around 67% of the solid was recovered as residue having a lipid content of ∼27% (∼103% recovery). Furthermore, an increase in the ethanol extractables was observed and found to be ∼11%, containing ∼21% of polyphenols in gallic acid equivalent. Moreover, this approach allows a potential energy savings of as much as ∼48% when compared to conventional approaches. Lipids remained intact in the solid residue with structural lipids released during direct hydrolysis of non-delipidated SCG, thereby resulting in a lipid recovery beyond 100%. The presence of lipids does not hinder the recovery of the available sugars. Direct utilization of non-delipidated SCG potentially reduces the energy requirements during processing and facilitates recovery of bioactive components.

KEYWORDS:

• Dilute acid hydrolysis
• lipids
• reducing sugars
• spent coffee grounds
• Taguchi method

Acknowledgements

The authors would like to acknowledge the financial support of the University of San Carlos – Office of Research through the research grant approved for the 2^nd semester of the academic year 2015–2016.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

University of San Carlos - Office of Research [grant number Faculty Research AY 2016–2017]