Improving yield and composition of protein concentrates from green tea residue in an agri-food supply chain: Effect of pre-treatment

- Produce protein from waste of tea factory is crucial for adding value sustainably.
- Combined ethanol and viscozyme pre-treatment had best effect on protein extraction.
- Using ethanol obtained polyphenol and Viscozyme® L obtained carbohydrates.
- Using ethanol reduced protein colour and Viscozyme® L improved protein nutrients.
- Production of bio-products can be added to the existing process.

Rather than improving crop-production yield, developing biorefinery technology for unused biomass from the agri-food supply chain may be the crucial factor to reach sustainable global food security. A successful example of food-driven biorefinery is the extraction of protein from green tea residues, however, alkali usage is high and the resulting low protein quality limits its application. The research objective was to investigate the influence of pre-treatments with ethanol, Viscozyme® L and/or H2O2 on the subsequent alkaline protein extraction, and on their possible products for food applications. Polyphenols and/or pigments can be obtained by ethanol pre-treatment. Galacturonic acid and glucose can be obtained using Viscozyme® L. Pre-treatments using ethanol or Viscozyme® L individually reduced alkali consumption by 25% and improved protein extraction yield and purity. Their combination has the best effect. Additionally, pre-treatment using 50% ethanol reduced browning by 59% while pre-treatment using Viscozyme® L increased contents of arginine, threonine, and serine in the final alkaline protein extract. H2O2 pre-treatment had a negative effect on the alkaline protein extraction. These pre-treatments and protein extraction can be added to the existing process.