By Jenn Roloson, Summer Research Assistant, OMAFRA

For several years research has been ongoing to determine the best way to maximize oil extraction in the shortest amount of time. Preliminary work was done in 2014 to see if packing the vessel and the amount of flower material in the vessel had any effect on the overall oil extraction efficiency. It was found that having the vessel completely full and packed produced the highest oil extraction per kg of flower material and oil extracted per minute. This was taken a step further this year by comparing oil extraction using different amounts of flower material and comparing a packed vessel to an unpacked vessel.

The trial was conducted using a 40L stainless steel distiller. There were 8 treatments altogether, 4 packed and 4 unpacked with the vessel 25, 50, 75 and 100% full for each packing type. All of the treatments were only replicated once and the vessel was packed more than last year based on the total flower weight in the packed vessel.

Overall the 100% full packed treatment had the highest oil extraction per kilogram of flower material and the highest oil extracted per minute of run, but it took longer to extract all of the oil in this treatment(Table 1). Most of the oil extracted for all treatments could be seen within the first 30 minutes.

For time efficiency both the unpacked and packed 100% full treatments produced higher oil yields per minute of distilling. This suggests that how the vessel is packed does not play a huge part in influencing the oil yield per minute.

Table 1. Effect of packing and amount of flower material in the distillation vessel on lavender essential oil extraction.

The overall trend that was observed was the oil yield per kilogram was higher for the treatments that were 25% full compared to the treatments where the vessel was 100% full (Figure 1). The full vessel might not have produced high oil yields due to the steam finding channels around the flower material. The 25% full vessel could produce higher oil per kilogram due to the steam being able to reach all of the flower material. It is likely that more even filling of the vessel would have resulted in higher oil yield per kilogram of flowers when the vessel was full. These preliminary results suggest that for a higher efficiency of time the vessel should be 100% full and packed. If there is less flower material the vessel should be packed evenly to get the maximum amount of oil, but the depth of plant material in the vessel is less important.

Figure 1. Oil extracted per kg of flower material.

The overall trend that was observed was the oil yield per kilogram was higher for the treatments that were 25% full compared to the treatments where the vessel was 100% full (Figure 1). The full vessel might not have produced high oil yields due to the steam finding channels around the flower material. The 25% full vessel could produce higher oil per kilogram due to the steam being able to reach all of the flower material. It is likely that more even filling of the vessel would have resulted in higher oil yield per kilogram of flowers when the vessel was full. These preliminary results suggest that for a higher efficiency of time the vessel should be 100% full and packed. If there is less flower material the vessel should be packed evenly to get the maximum amount of oil, but the depth of plant material in the vessel is less important.

To ensure better oil yield the vessel should be packed fairly consistently in a way that prevents the steam from forming channels around the flower material, and thus missing oil. Different quantities of flowers and how the vessel is packed can benefit each grower differently depending on how much flower material they have and the amount of time that they have to designate to distilling oil.