Towards efficient grass-clover biorefining: Influence of harvesting methods and delayed processing

This paper describes the effects of different harvesting techniques and processing time delays on the yield and quality of the protein extracted through biorefining from a grass-clover mixture grown in Denmark. Two harvesting methods were employed—mowing and chopping—with subsequent processing occurring immediately or after 6 or 12 hours. The extraction process produced protein concentrates with crude protein (CP) and amino acid (AA) contents equivalent to soybean meal (SBM). The standardised ileal digestibility (SID) of CP in protein concentrate produced immediately after harvest was 71.0 % and 69.2 % from the mowed and chopped biomass, respectively (P > 0.05). Delayed processing diminished SID of CP (P = 0.005) and of all AA (P < 0.05). There was an overall effect of harvest method on SID of CP (P = 0.006) and all AA (P < 0.05), with lower values from the chopped biomass. The calculated yield of protein extracted from mowed biomass without delay was 56.8 kg digestible CP/hectare and 43.4 kg/hectare after 12 hours. In contrast, the calculated yield from chopped biomass was only reaching 29.4 kg/hectare following a 12-hour delay. This research underscores the importance of harvesting method selection and timely processing in maximising protein extraction efficiency and digestibility. The results advocate for enhanced logistics and handling practices in biorefining operations to improve efficiency and resource utilisation in protein production.