Lysolecithins versus synthetic emulsifiers

Synthetic emulsifiers are often based on polyethylene glycol ricinoleate (PEGR) and are, like lysolecithins, amphiphilic molecules. Synthetic emulsifiers however are relatively more hydrophilic compared to lysolecithins, as they have a higher hydrophilic-lipophilic balance (HLB) value.

Because of this high HLB value, synthetic emulsifiers are mainly used in the pelleting process of feed production for the promotion of oil-in-water emulsions and maintaining pellet quality. However, their high HLB value falls outside the optimal HLB range for oil-in-water emulsions required for efficient fat digestion. Furthermore, a higher concentration of synthetic emulsifiers is needed to establish an emulsion as compared to lysolecithins. Synthetic emulsifiers are also larger in size than lysolecithins, resulting in less finely dispersed emulsions with larger emulsified fat droplets and interference with the action of bile salts.

As a consequence, the environment for the digestive enzymes is less optimal, resulting in a lower enzymatic potential of digestive enzymes. Compared to lysolecithins, synthetic emulsifiers create bigger and less hydrophilic mixed micelles which makes the transport through the aqueous environment of the digestive tract less efficient. In contrast to lysolecithins, synthetic emulsifiers do not interfere with the intestinal membrane and therefore do not improve membrane permeability. For effective fat digestion and utilisation, and thus animal performance, proper fat emulsification is key and this is why choosing the right emulsifier is important. A recent trial shows that not only the type of emulsifier but also the level of lysolecithins plays a prominent role in determining the efficacy of emulsifiers.

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