Quality preservation of deliberately contaminated milk using thyme free and nanoemulsified essential oils

Abstract

The objective of this study is to evaluate the effect of either a solution of Thymus capitatus essential oil or its nanoemulsion on the quality of milk contaminated by bacteria. After 24h of S. aureus inoculation, bacterial growth reached 202×10(3)CFU/ml in the presence of the essential oil while it was limited to 132×10(3)CFU/ml when treated with nanoemulsion. The reduction of antioxidant capacity of milk treated with essential oil was higher when treated with nanoemulsion. Moreover, free essential oil was more efficient in protecting proteins from degradation than the nanoemulsion. For instance, after 24h of E. hirae contamination, 26% of the total proteins were consumed in the presence of nano-encapsulated essential oil, while only 14% of the initial content was consumed when free essential oil was added. Concerning milk acidity increase and the inhibition of peroxide production, no statistical differences have been recorded between the use of free essential oil or its nano-emulsion. In conclusion, bulk or nano-encapsulated T. capitatus essential oil preserve milk quality and can extend its shelf life.

Physical and sensory characteristics and probiotic survival in ice cream sweetened with various polyols

“…Results were expressed as gram of lactic acid equivalent per litre (Jemaa et al . ). The overrun of the final product was determined on the seventh day of storage at −22 °C according to PN ().…”

“…Titratable acidity of samples was determined in melted ice cream by titration with 0.1 N NaOH, using phenolphthalein as an indicator. Results were expressed as gram of lactic acid equivalent per litre (Jemaa et al 2017). The overrun of the final product was determined on the seventh day of storage at À22°C according to PN (2002).…”

Application of the mixture design for optimum antimicrobial activity: Combined treatment of Syzygium aromaticum , Cinnamomum zeylanicum , Myrtus communis , and Lavandula stoechas essential oils against Escherichia coli

“…Semi‐skimmed UHT milk (larger frequency of consumption) was purchased from a local supermarket and supplemented with 2 mg/ml EOs and then E. coli strain was added to obtain a final bacterial population of about 10 5 ·CFU·ml −1 . Afterward, milk was incubated for 24 hr at 37°C (Ben Jemaa et al, ).…”

“…After that, 1 ml from the appropriate dilution was put in Petri dish then a Mueller–Hinton medium was added, and the Petri dishes gently mixed before being incubated for 24 hr at 37°C. Finally, the result was expressed as colony forming units (log (10)·CFU·ml −1 ) as described by Ben Jemaa et al ().…”

Encapsulation of Natural Bioactive Compounds: Nanoemulsion Formulation to Enhance Essential Oils Activities

“…For instance, it has been demonstrated that in cheese, an increase up to 100-fold of the essential oil concentration was required to assure comparable antimicrobial efficacy of the in vitro model system [47]. The difference in the essential oil antimicrobial efficiency between in vitro and real food system can be attributed to the essential oil dissolution in the lipid phase of an ailment, inducing the decrease of their concentration in the aqueous phase [48]. However, it is in the aqueous phase where pathogenic bacteria typically proliferate [46].…”