Biological Activity and Phytochemical Characteristics of Star Anise (Illicium verum) Essential Oil and Its Anti- Salmonella Activity on Sous Vide Pumpkin Model

Abstract

Illicium verum, commonly known as star anise, represents one of the notable botanical species and is recognized for its rich reservoir of diverse bioactive compounds. Beyond its culinary application as a spice, this plant has been extensively utilized in traditional medicine. Given the contemporary emphasis on incorporating natural resources into food production, particularly essential oils, to enhance sensory attributes and extend shelf life, our study seeks to elucidate the chemical composition and evaluate the antibacterial (in vitro, in situ) and insecticidal properties of Illicium verum essential oil (IVEO). Also, microbiological analyses of pumpkin sous vide treated with IVEO after inoculation of Salmonella enterica were evaluated after 1 and 7 days of study. GC/MS analysis revealed a significantly high amount of (E)-anethole (88.4%) in the investigated EO. The disc diffusion method shows that the antibacterial activity of the IVEO ranged from 5.33 (Streptococcus constellatus) to 10.33 mm (Citrobacter freundii). The lowest minimal inhibition concentration was found against E. coli and the minimum biofilm inhibition concertation was found against S. enterica. In the vapor phase, the best antimicrobial activity was found against E. coli in the pears model and against S. sonei in the beetroot model. The application of the sous vide method in combination with IVEO application decreased the number of microbial counts and eliminated the growth of S. enterica. The most isolated microbiota identified from the sous vide pumpkin were Bacillus amyloliquefaciens, B. cereus, B. licheniformis, and Ralstonia picketii. Modifications to the protein composition of biofilm-forming bacteria S. enterica were suggested by the MALDI TOF MS instigations. The IVEO showed insecticidal potential against Harmonia axyridis. Thanks to the properties of IVEO, our results suggest it can be used in the food industry as a natural supplement to extend the shelf life of foods and as a natural insecticide.

Keywords: anti-Salmonella effect on pumpkin model; in situ antimicrobial effect on pear and beetroot; in vitro activity against G+ and G−; phytochemical composition; star anise.

Figure 1

Isometric elaboration of the data in Table 4 (In situ analysis of the antimicrobial activity of the vapor phase of IVEO in pear and beetroot models). Green: ≤60%; Red: >60%.

Figure 2

Total viable count of pumpkin sous vide samples on days 1 and 7. The data represent the mean (±SD) of three samples. The control group denotes a fresh pumpkin sample treated at 50–65 °C for 5 to 25 min after being packed in polyethylene bags and stored at 4 °C. The control vacuum group represents a fresh pumpkin sample treated under the same conditions but vacuum-packed in polyethylene bags and kept at 4 °C. The EO group comprises vacuum-packed fresh pumpkin treated with 1% IVEO, stored at 4 °C, and treated for 5–25 min at 50–65 °C. The Salmonella group includes vacuum-packed fresh pumpkin treated with S. enterica, stored at 4 °C, and treated for 5–25 min at 50–65 °C. The Salmonella + EO group consists of vacuum-packed fresh pumpkin treated with both S. enterica and 1% IVEO, stored at 4 °C, and treated for 5–25 min at 50–65 °C.

Figure 3

Coliform bacteria on pumpkin sous vide samples on days 1 and 7. The data represent the mean (±SD) of three samples. The control group denotes a fresh pumpkin sample treated at 50–65 °C for 5 to 25 min after being packed in polyethylene bags and stored at 4 °C. The control vacuum group represents a fresh pumpkin sample treated under the same conditions but vacuum-packed in polyethylene bags and kept at 4 °C. The EO group comprises vacuum-packed fresh pumpkin treated with 1% IVEO, stored at 4 °C, and treated for 5–25 min at 50–65 °C. The Salmonella group includes vacuum-packed fresh pumpkin treated with S. enterica, stored at 4 °C, and treated for 5–25 min at 50–65 °C. The Salmonella + EO group consists of vacuum-packed fresh pumpkin treated with both S. enterica and 1% IVEO, stored at 4 °C, and treated for 5–25 min at 50–65 °C.

Figure 4

Krona chart: Species of microorganisms isolated from sous vide pumpkin after 1 day.

Figure 5

Krona chart: Species of microorganisms isolated from sous vide pumpkin after 7 days.

Figure 6

MALDI-TOF mass spectra of S. enterica on the third, fifth, seventh, ninth, twelve, and fourteenth days. A-day 3, B-day 5, C-day 7, D-day 9, E-day 12, F-day 14. S = stainless steel; G = glass; PC = planktonic cells; SE = S. enterica.

Figure 7

S. enterica dendrogram created with planktonic cell MSPs and control. S = stainless steel; G = glass; PC = planktonic cells; SE = S. enterica.