From by-product to functional ingredient: Incorporation of avocado peel extract as an antioxidant and antibacterial agent

The work studied the possibility of avocado peel extracts replacing synthetic preservatives in mayonnaise. The extracts exhibited an IC₅₀ (concentration of extract that inhibits 50% of DPPH) value of 38.23 ± 2.33 μgextract∙mL⁻¹ and were able to inhibit more the growth of Gram-positive bacteria (Staphylococcus aureus and Staphylococcus epidermidis), compared to ascorbic acid, proving its potential to be used as a preservative. Five mayonnaises were produced (1 negative control, 2 positive controls –with 0.02% of BHT (butylated hydroxytoluene) and 0.06% of ascorbic acid, and 2 samples –with 0.5% and 1.0% of extract), and stored at 4 °C. All mayonnaises exhibited no microbial growth and inhibited the growth of Escherichia coli and Staphylococcus aureus, proving their potential to replace synthetic preservatives. Oxidative stability revealed that the samples with extract displayed analogous results to those with synthetic antioxidants, proving the possibility of the extract replacing them. The results displayed the possibility to incorporate avocado peel extracts in mayonnaises, without compromising their stability, and their potential to replace commonly used preservatives while creating value-added foods. Avocado peels are a major by-product of avocado processing, contributing significantly to the waste generated every year. Nevertheless, it can be used to obtain extracts rich in phenolic compounds with a wide array of biological properties, that can be incorporated into different matrixes for various industries, such as food, cosmetics, and pharmaceutical. Furthermore, avocado peels are an easy-to-obtain by-product, with industrial relevance, since it allows contact between local farmers and restaurants with big industries in order to reduce the impact of this by-product while creating a value chain. Therefore, this article focuses on the incorporation of avocado peel extract into mayonnaise and its outcomes on the physical and chemical stability of the food.