Using oil immersion to deliver a naturally-derived, stable bromoform product from the red seaweed Asparagopsis taxiformis

Asparagopsis taxiformis (Asparagopsis) inhibits the production of enteric methane in ruminants. A next critical step in the implementation of this technology is the delivery of a naturally-derived product that maximises the concentration and longer-term retention of bromoform. This study (1) quantified the effects of solvent (water or oil), initial processing (intact or homogenised), and temperature (4 or 25 °C) on the stabilisation of bromoform over time, and (2) assessed the effects of increasing the biomass loading (g biomass mL−1 solvent) of Asparagopsis on the concentration of bromoform in a formulation. The most effective method was to homogenise freshly-collected Asparagopsis in oil, which resulted in the highest concentration of bromoform (19.2 ± 2.1 mg g−1 dw algae) in the homogeneous product in the shortest time (one day). In addition, the final product had a shelf life of at least 12 weeks, even when stored at room temperature (25 °C). Notably, there was an increase in the concentration of bromoform per mL of oil between each increment of biomass loading tested, with the highest concentration of bromoform of 4.04 ± 0.51 mg mL−1 in the maximum ratio of biomass to oil of 120 g 100 mL−1. The method described here provides a viable processing alternative to freeze-drying, resulting in the stabilisation of the bromoform from Asparagopsis, which will be critical to the success of using Asparagopsis on a larger scale to mitigate the production of methane in ruminants.