Use of Natural Polymers for the Encapsulation of Eugenol by Spray Drying

<b>Background:</b> Eugenol is a colourless or yellowish compound whose presence in clove essential oil surpasses the 75% of its composition. This phenylpropanoid, widely used as an antiseptic, anaesthetic and antioxidant, can be extracted by steam distillation from the dried flower buds of <i>Syzygium aromaticum</i> (L.). Due to its chemical instability in presence of light and air, it should be protected when developing a formulation to avoid or minimise its degradation. <b>Methods:</b> A promising approach would be encapsulation by spray drying, using natural coating products such as maltodextrin, gum arabic, and soy lecithin. To do so, a factorial design was carried out to evaluate the effect of five variables at two levels (inlet temperature, aspirator and flow rate, method of homogenisation of the emulsion and its eugenol:polymers ratio). Studied outcomes were yield and outlet temperature of the spray drying process, eugenol encapsulation efficiency, and particle size expressed as d_(0.9). <b>Results:</b> The best three formulations were prepared by using a lower amount of eugenol than polymers (1:2 ratio), homogenised by Ultra-Turrax^®, and pumped to the spray dryer at 35 m³/h. Inlet temperature and flow rate varied in the top three formulations, but their values in the best formulation (DF22) were 130 °C and 4.5 mL/min. These microcapsules encapsulated between 47.37% and 65.69% of eugenol and were spray-dried achieving more than a 57.20% of product recovery. Their size, ranged from 22.40 μm to 55.60 μm. <b>Conclusions:</b> Overall, the whole spray drying process was optimised, and biodegradable stable polymeric microcapsules containing eugenol were successfully prepared.