*3.3. Emulsification Activity*

Stability is an important indicator when determining the commercial value of food products with water-in-oil emulsions. However, these emulsions are thermodynamically unstable due to the large interfacial area of the dispersed phase [36]. Their structural organization and amphiphilic nature make biosurfactants excellent emulsifiers acting at the oil–water interface, promoting the thermodynamic stability of unstable systems. Moreover, the characteristics of biosurfactants enable these natural compounds to interact with carbohydrates and proteins in food products [37].

The choice of vegetable oils in the emulsification tests was based on their importance and use in the food industry. Soybean oil stands out in terms of production and consumption whereas the other oils were selected due to their specific beneficial and functional properties for human consumption. In particular, peanut oil has a high vitamin E content, canola oil has a low content of saturated fatty acids and contains omega 3, and corn oil has essential acids and is considered to be of a high quality [38]. The emulsifying capacity of the biosurfactant produced by *B. cereus* at different concentrations against the selected vegetable oils is displayed in Table 4 in terms of the emulsification index (E24).

biosurfactant.

a reference.

cookie.

**Variable Standard** 

Carbohydrates

Energy Value


**Table 4.** Emulsification index (E24) of the biosurfactant produced by *B. cereus* UCP 1615 for different vegetable oils (data expressed as mean ± SD of the triplicate determinations). Data are expressed in %.

The results indicated that the biosurfactant was able to ensure a satisfactory emulsification of all the oils studied. As expected, the increase in the concentration of the biosurfactant led to an E<sup>24</sup> increase. The best results were achieved at concentrations of 5.0 and 10.0 mg/mL, with E<sup>24</sup> values ranging from 54 to 68%.

Few studies have investigated the capacity of biosurfactants produced by the genus *Bacillus* to emulsify vegetable oils or the application of these natural compounds as bioemulsifiers in food products. A study involving a biosurfactant produced by *Bacillus subtilis* ICA56 reported E<sup>24</sup> > 50% for soybean oil [39]. Studies involving bioemulsifiers produced by *Candida albicans* reported E<sup>24</sup> values around 50% for peanut, mustard, olive and soybean oils [21]. The bioemulsifier from *Candida utilis* showed indices around 30% for corn and sunflower oil under different conditions of pH and salinity [40]. The biosurfactant produced by *C. bombicola* achieved indices of 56% for corn oil, 51% for soybean oil, 69% for peanut oil and 50% for canola oil [31]. Thus, the present results were consistent with the findings described in the literature.
