*Article* **Application of a Biosurfactant Produced by** *Bacillus cereus* **UCP 1615 from Waste Frying Oil as an Emulsifier in a Cookie Formulation**

**Italo J. B. Durval 1,2 , Beatriz G. Ribeiro 1,2, Jaciana S. Aguiar <sup>3</sup> , Raquel D. Rufino 2,4 , Attilio Converti 2,5,\* and Leonie A. Sarubbo 2,6,\***


**Abstract:** Biosurfactants have attracted increasing interest from the food industry due to their emulsifying, foaming and solubilizing properties. However, the industrial use of microbial biosurfactants has been hampered by the high production costs related mainly to the use of expensive substrates. The search for low-cost alternative substrates is one of the strategies adopted to overcome this problem. In the present study, a biosurfactant produced by *Bacillus cereus* UCP1615 by fermentation in a medium supplemented with waste frying soybean oil as a low-cost substrate was evaluated as a bioemulsifier for the production of cookies. The biosurfactant was evaluated for its emulsifying capacity against different vegetable oils, antioxidant activity and toxicity, demonstrating favorable results for use in food. In particular, it showed satisfactory antioxidant activity at the tested concentrations and no cytotoxicity to the L929 (mouse fibroblast) and Vero (monkey kidney epithelial) cell lines using the MTT assay. The biosurfactant was then added at different concentrations (0.25%, 0.5% and 1%) to a standard cookie dough formulation to evaluate the physicochemical characteristics of the product. Cookies formulated with the biosurfactant exhibited similar energy and physical characteristics to those obtained with the standard formulation but with a lower moisture content. The biosurfactant also ensured a good preservation of the cookie texture after 45 days of storage. These results suggest that the biosurfactant has a potential application as a green emulsifier in accordance with the demands of the current market for biocompatible products.

**Keywords:** biosurfactant; bioemulsifier; waste frying oil; *Bacillus cereus*; food additives; cookie
