AROMAS AND PELLETING TEMPERATURES – ARE THEY COMPATIBLE?

From a chemical viewpoint, the perception of smell occurs when there is an interaction between an odor particle and olfactory receptors. Volatility plays a key role since it is necessary for this particle to enter a gaseous state and reach the receptors via air. Temperature and pressure affect the volatility, hence why the use of aromas in the processing of pelleted feeds has been a recurring problem.

To better understand this process, the Norel’s R&D Department designed a trial divided in two parts: quantification of the components of the aroma in the feed and the sensory evaluation of aroma perception. The objectives were both to assess the impact of pelleting temperature on an aroma widely used in piglet feeds (Fluidarom® 1972 Raspberry) and to study whether an association exists between the physical losses and aroma perception.

The first part was a quantitative analysis using the Headspace GC-MS method, making it possible to calculate the physical losses due to volatility. The second, a sensory analysis through a series of tests carried out by 16 panelists, all of them professionally related to animal nutrition without any specialist knowledge of aromas.

According to the data obtained, it does not appear to be a relationship between the two determinations, since there were losses up to 38% depending on the pelleting temperature but the panelists were not able to discern a difference in the intensity of the aroma of the different samples. This leads us to draw two conclusions:

• The perception of Fluidarom 1972® Raspberry was not significantly affected by increases in pelleting temperature. This makes it a desirable aroma where high temperatures are reached during feed processing.
• The physical aroma losses caused by pelleting temperature observed during the quantitative analysis were not reflected in the sensory analyses.

That highlights to the importance of aromas having the right formulation. Substances lost during pelleting had little or no bearing on the identity of the aroma. This study therefore demonstrates that if the volatile and non-volatile elements of an aroma are combined effectively, it is possible to maintain perception despite the pelleting temperature.