Mixture design methodology and predictive modeling for developing active formulations using essential oils and citrus extract against foodborne pathogens and spoilage microorganisms in rice

Abstract

The antibacterial and antifungal effects of six plant‐derived essential oils (EOs) and two types of citrus extracts (CEs) were studied against two pathogenic bacteria (Salmonella Typhimurium and Escherichia coli O157:H7) and three fungi (Aspergillus niger, Penicillium chrysogenum, and Mucor circinelloides). A broth microdilution assay and checkerboard method were used to measure the minimal inhibitory concentration (MIC) of each extract and the possible interactions between them. The MIC assay showed that cinnamon EO, Mediterranean EO, Southern formulation, citrus EO, organic citrus extract (OCE), and natural citrus extract (NCE) had the highest antimicrobial and antifungal activity. The checkerboard method showed that the Mediterranean EO+OCE combination acted in synergy against all tested pathogens. A centroid mixture design was used to develop active formulations by predicting optimal concentrations of EO/CEs for increased antibacterial/antifungal activity. A mixture of four formulations (625 ppm OCE, 313 ppm Mediterranean EO, 625 ppm citrus EO, and 313 ppm cinnamon EO) named as active formulation 1, and the mixture from five formulations (625 ppm NCE, 625 ppm Asian formulation, 313 ppm Southern formulation, 625 ppm cinnamon EO, and 313 ppm savory thyme EO) named as active formulation 2, were formulated and tested because of their high microbicidal effectiveness. In situ tests with rice showed a significant reduction (P ≤ 0.05) of all tested pathogenic bacteria and fungi from the vapor of active formulations 1 and 2 after 28 days of storage. Practical Application Active formulations (essential oils and citrus extracts) developed in the study are highly effective against foodborne pathogens. Active formulations in this study could be used as natural preservatives in the food industry for controlling foodborne diseases and spoilage organisms in stored foods.

Evaluation of bioactive low‐density polyethylene (LDPE) nanocomposite films in combined treatment with irradiation on strawberry shelf‐life extension

“…To obtain the best antibacterial and antifungal properties of the active LDPE films, the levels and proportions of all ingredients (independent variables) were determined by central composite design (CCD) using Design‐Expert software (version 11, Stat‐Ease, Inc., Minneapolis, MN, USA) (Begum et al., 2022; Radfar et al., 2020). A total of 17 experimental runs were performed with three replications each (Table 1).…”

“…The experiments were performed three times. The models’ level of significance was assessed by the analysis of the variance (ANOVA) with alpha = 0.05 (Begum et al., 2022; Falleh et al., 2019).…”