Incorporation of sonicated purple corn cob extracts into food emulsions: effects on physicochemical properties, antioxidant activity, and shelf life

The goal of this study was to develop food emulsions incorporating purple corn cob extracts as a functional ingredient. Concentrated hydroalcoholic extracts were obtained using ultrasound at 50 °C. Emulsions with purple corn cob extract were prepared at different concentrations: mayonnaise with 0.2% anthocyanins from purple corn cob extract (EE1), mayonnaise with 0.25% anthocyanins from purple corn cob extract (EE2), and mayonnaise with 0.3% anthocyanins from purple corn cob extract (EE3), and stored for 45 days for subsequent physicochemical, rheological, and microbiological evaluation. Phenolic compounds and antioxidant activity were determined by in vitro assays, while oxidative stability was measured using the Rancimat method. Emulsions with sonicated extracts met food regulatory standards (pH: 3.5–4; peroxide value: 1.33–1.57 meq O2 kg-1; acidity: 0.35–0.56 mg oleic acid g-1) and exhibited pseudoplastic behavior similar to the control, although viscosity decreased by 50% by day 45. At a temperature of 110 °C and a constant air flow of 20 L/h, EE3 remained stable for 8.6 h, giving it a higher index of oxidative stability. Additionally, it presented higher values of phenolic compound content (38.78 mg gallic acid g-1 emulsion) and antioxidant activity (23.487 mg Trolox g-1 emulsion), by 8% and 13%, respectively, compared to the sample with synthetic antioxidant (EDTA), and its shelf life was 153.3 days. No Salmonella was detected in any formulations. Molds and yeasts began growing from day 7 but were less pronounced in EE3. The identification of Delphinidin-3-O-glucoside, Cyanidin-3-O-glucoside, and p-Coumaroylquinic acid in the sonicated extract highlights its potential as a functional ingredient in food emulsions.