Antimicrobial Properties of Lyophilized Extracts of Olive Fruit, Pomegranate and Orange Peel Extracts against Foodborne Pathogenic and Spoilage Bacteria and Fungi In Vitro and in Food Matrices

Abstract

Several novel antimicrobials with different concentrations of olive, pomegranate, and orange fruit pulp extracts were produced from agricultural byproducts and, after lyophilization, their antimicrobial activity and potential synergistic effects were evaluated in vitro and in food samples against foodborne pathogenic and spoilage bacteria and fungi. The Minimum Inhibitory of the tested bacteria was 7.5% or 10%, while fungi were inhibited at a concentration of 10% or above. The optical density of bacterial and yeast cultures was reduced to a different extent with all tested antimicrobial powders, compared to a control without antimicrobials, and mycelium growth of fungi was also restricted with extracts containing at least 90% olive extract. In food samples with inoculated pathogens and spoilage bacteria and fungi, the 100% olive extract was most inhibitory against E. coli, S. typhimurium, and L. monocytogenes in fresh burger and cheese spread samples (by 0.6 to 1.8 log cfu/g), except that S. typhimurium was better inhibited by a 90% olive and 10% pomegranate extract in burgers. The latter extract was also the most effective in controlling the growth of inoculated fungi (Aspergillus niger, Penicillium italicum, Rhodotorula mucilaginosa) in both yogurt and tomato juice samples, where it reduced fungal growth by 1–2.2 log cfu/g at the end of storage period. The results demonstrate that these novel encapsulated extracts could serve as natural antimicrobials of wide spectrum, in order to replace synthetic preservatives in foods and cosmetics.

Effects of Functional Coatings Containing Chitosan, Orange Peel and Olive Cake Extracts on the Quality Attributes of Cucumber during Cold Storage

“…TVC ( Figure 1 a) and yeast and mold counts ( Figure 1 b) were the highest in the uncoated cucumber samples followed by those coated with 2% chitosan only, whereas the lowest counts were seen in cucumber coated with functional materials (2% OCE and 2% OPE), suggesting the protective effects of these materials against spoilage microbes in cucumber samples. The reduction in TVC and mold and yeast counts in the coated cucumber with chitosan containing OCE and OPE is likely due to the presence of the phytochemicals with high antimicrobial activity of olive cake and orange peel extract as reported previously [ 22 , 30 ]. In addition, the coating material formed a protective layer on the surface of the cucumber samples, thereby reducing the microbial contamination and growth [ 9 ].…”

“…A food product carrying less than 6 log CFU is generally considered safe, and the results presented in Figure 1 indicate that all OPE- and OCE-chitosan coated samples carried a TVC count less than this value for up to 14 days of refrigerated storage. The TVC count became higher than 6 log CFU in both uncoated and chitosan coated samples, indicating the potential of the antimicrobial effects of OPE and OCE [ 22 ]. In agreement with these findings, previous reports demonstrated the edible coating of cucumber with carbon dots and chitosan [ 15 ], limonene and chitosan [ 7 ], guar gum [ 6 ], chitosan nanoparticles loaded with Cinnamomum zeylanicum essential oil [ 13 ], aloe vera gel and carboxymethyl cellulose composite [ 5 ], and saffron petal extract containing konjac glucomannan edible films [ 17 ].…”

“…To date, cucumber has been treated with different types of edible coating using various types of chitosan-based [ 7 , 12 , 13 , 14 , 15 , 16 ], gum-based [ 4 , 6 , 17 ], starch-based [ 18 , 19 ] and cellulose-based [ 5 ] edible coatings, with or without active ingredients from natural sources, and has been found to improve the storage stability of the product. Olive cake and orange peel are the major byproducts of olive oil and orange juice industries, and these underutilized byproducts are considered an essential source of phytochemicals with high antioxidant and antimicrobial activities [ 20 , 21 , 22 ]. Nonetheless, there is no report on the use of edible coating of cucumber with olive cake extract (OCE) and orange peel extract (OPE).…”

Antimicrobial Activity and Phytochemical Analysis of Solvent Extraction of Citrus reticulata Peels

“…Transforming citrus juice manufacturing waste into value-added items can significantly alleviate these concerns (Mckay et al, 2021). Citrus peels are high in flavonoids, essential oils, organic acids, flavone glycosides, and phenols, which are uncommon in other plants, according to studies (Mitsagga et al, 2021). Distinctive polyphenol compounds present in citrus include hesperidin, neohesperidin, naringin, and narirutin (Li et al, 2020).…”

Uso do extrato de romã (Punica granatum L.) na superfície dentinária erodida: ação antioxidante, resistência de união e análise morfológica da interface adesiva após envelhecimento

“…O processo de liofilização consiste na remoção da água do material por sublimação, em baixas temperaturas, portanto, não ocorre alteração química (perda de constituintes voláteis) pelo calor (Rodriguez et al, 2019). O produto liofilizado apresenta resistência à microrganismos devido à concentração de água residual ser mínima e permite manipular de forma adequada as concentrações necessárias para o experimento (Rodriguez et al, 2019;Mitsagga et al, 2021).…”