Three factors crucial for free fatty acid levels
HGCA – the cereals and oilseeds division of the Agriculture and Horticulture Development Board sought to identify the cause of particularly high FFA levels recorded in Scotland in 2012 by conducting a grower survey, in partnership with oilseed merchants.
FFAs are a concern for end users because they can make the oil unsuitable for human consumption and cause foaming in biofuels. FFA levels in excess of 2% can result in deductions to the price growers receive, reflecting the costs of removing them from the oil.
‘Three key factors’
Following analysis of the survey responses, three key factors were identified as contributing to the incidence of FFAs. The HGCA is planning to build on this initial work to explore these and other contributory factors leading to increased levels of FFA.
“Although this was a small, self-selecting survey, it indicates that harvesting too early or too late after desiccation can both increase the amount of free fatty acids,” said Dr Simon Oxley, senior research and knowledge transfer manager at HGCA. “Previous research suggests immature seeds in early harvest and pre-germination of seeds in late harvest increase FFA levels.”
The survey has also indicated that drying practices influence FFA content, with increased levels recorded when higher drying temperatures were used.
‘Greater throughput’
Dr Oxley suggested growers take this into account when selecting temperatures: “Higher drying temperatures allow greater throughput on drying equipment but can also increase FFA levels.” The survey also looked at whether other factors such as variety or region had an effect on FFA levels.
“The work so far hasn't indicated significant relationships with any other factor,” said HGCA data analyst Dr Ellie Marshall. “But we have to bear in mind that this research was conducted in one growing season. In future we intend to expand this work and explore all possible influences on FFA levels in more detail.”
