Shelf-life stability of Asparagopsis bromoform in oil and freeze-dried powder

Abstract

The idea of delivering bromoform from Asparagopsis using edible oil has gained momentum recently due to the improved processing time and that it is already a feed that many livestock producers use. The stability of bromoform in oil compared to freeze-dried product is still not well understood. To fill this gap, a systematic study was carried out to determine the effects of storage temperatures (40 °C, 25 °C, 4 °C and -20 °C), fluorescent light and exposure to open air, on the retention of bromoform in freeze-dried Asparagopsis (FD-Asp) and Asparagopsis oil (Asp-Oil) over 24-week period. In the absence of fluorescent light, Asp-Oil was a more effective way to preserve bromoform compared to FD-Asp due to either no change or higher Asp-Oil bromoform content (storage temperature dependent) after 24-week storage. Under the same conditions, FD-Asp bromoform content decreased by 74% at 40 °C, 53% at 25 °C, 6% at 4 °C, and no change of FD-Asp bromoform content at -20 °C. The presence of fluorescent light negatively affected Asp-Oil bromoform content at both 25 °C and 40 °C while the effect was insignificant on FD-Asp. The exposure of Asp-Oil to open air resulted in the decrease of bromoform content to below quantification limit (0.18 mg g−1) on week 8 for 40 °C sample and on week 16 for 25 °C sample. This study provides empirical evidence on the stabilising effect of oil in preserving bromoform extracted from Asparagopsis, confirming it is a more attractive medium to deliver bromoform compared to the freeze-dried powder form.