Effects of chitosan incorporated with basil seed gum and nettle (Urtica dioica L.) essential oil on the quality of beef burger during refrigerated storage

Investigating the inhibitory effect of nettle (Urtica dioica L.) essential oil and Pickering nanoemulsion on some pathogenic bacteria inoculated into pizza cheese

The aim of the present research was to evaluate the effect of Urtica dioica L. (nettle) essential oil (in the forms of Pickering nanoemulsion (NEO) and free (EO)) on microbial, chemical and sensory changes of pizza cheese stored at 4 °C for 12 days. For this purpose, Escherichia coli and Listeria monocytogenes were inoculated into pizza cheese. In all tests, the control group had the lowest score after 12 days of storage. In the antimicrobial assay test in different treatments, NEO4% treatment decreased the growth of E.coli from 4 (0th day) to 3.3 log CFU/g (12th day) and the growth of L. monocytogenes from 3.8 (0th day) to 3.1 log CFU/g (12th day). The minimum inhibitory concentration (MIC) of NEO and EO for E.coli and L. monocytogenes was 0.62 ± 0.01 mg/mL. Additionally, the minimum bactericidal concentration (MBC) of EO and NEO for E. coli was 25 ± 0.1 mg/mL, and for L. monocytogenes was 1.25 ± 0.1 mg/mL. At day 12, almost all treatments (free form and nano) had relatively similar pH. In our study, the minimum and maximum value of DPPH was detected in the treatment of NEO1% (31.25 ± 1.50 %) and BHT200 (96.40 ± 2.5 %), respectively. Also, on the 12th day of the test, the NEO treatment obtained the highest score in all sensory tests (appearance & color, body & texture, odor and overall acceptability). According to the findings of the present study, Pickering emulsion form of nettle EO increases the storage period of pizza cheese.

Effect of Urtica dioica L. Essential oil (forms of free and nanoliposome) on some inoculated pathogens (Escherichia coli and Listeria monocytogenes) in minced camel meat

The goal of research was to investigate the impact of nanoliposome and free forms of nettle (Urtica dioica L.) essential oil (EO) on sensory, chemical and microbial properties of minced camel meat during storage at 4 °C. In our investigation, Listeria monocytogenes and Escherichia coli were inoculated into minced camel meat. The outcomes expressed the zeta potential, particle size, polydispersity index and efficiency of encapsulation of prepared nanoliposome were -17.5 mV to -12.8 mV, 143 to 158 nm, 0.77 ± 0.05 to 0.86 ± 0.07 Mw/Mn and 50.26-67.28 %, respectively. Also, according to the microbial analysis, the MIC of EO and nanoliposome-EO (N-EO) for E.coli was 25 ± 2.5 and 25 ± 2.1 mg/mL, respectively, and for L. monocytogenes was 12.5 ± 2.1 and 12.5 ± 2.1 mg/mL, respectively, and the MBC of EO and N-EO for L. monocytogenes was 50 ± 3.1 and 50 ± 3.2 mg/mL, respectively, and for E. coli was 50 ± 2.2 and 50 ± 2.2 mg/mL, respectively. The highest of 2,2-Diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP) assay were detected in the BHT 200 (94.7 ± 2.7 and 95.6 ± 3.2, respectively) and lowest of them were detected NEO1% (33.7 ± 12.2 and 22.37 ± 0.22, respectively). After 18 days, the minimum value of pH was identified in the N-EO 2 % group incubated with L. monocytogenes (with pH = 6.9) and E. coli (with pH = 6.87). Furthermore, after 18 days of storage, the minimum TVB-N (total volatile basic nitrogen) value was observed in the N-EO group (26.89 mg N/100 g) and the maximum TVB-N value was observed in the control group (33.78 mg N/100 g). Finally, the N-EO and control treatment (during the experiment) had the highest and lowest sensory evaluation score, respectively. Finally, the N-EO group got a highest sensory score, whilst the group of control got the lowest acceptance score, after 18 days of storage. Based on the outcomes obtained from this research, using nettle (Urtica dioica L.) EO (in nanoliposome form) increases the storing time of minced camel meat.

Effect of a Chitosan Coating Enriched with an Olive Leaf Extract on the Characteristics of Pork Burgers

Chitosan coatings have been investigated for improving food shelf-life. The addition of an olive leaf extract could enhance its beneficial effect. The aim of this study was to evaluate the effectiveness of an olive leaf extract added to a chitosan coating in delaying deterioration in refrigerated pork burgers without additives packaged under a 40% oxygen and 60% carbon dioxide modified atmosphere. Some general parameters (microbial counts, instrumental color and texture, and lipid and protein oxidation) were measured over the storage of pork burgers without coating (Control), with a chitosan-based coating (Chitosan) and with a chitosan-based coating enriched with an olive leaf extract (Chitoex). The coating impacted the effect of the storage time on most parameters. Both coatings were especially effective at limiting the changes that occur over time in the headspace gases, some texture parameters (hardness, gumminess, and chewiness) and lipid oxidation, although the effect on the microbial counts was weak. Chitoex was more effective than Chitosan at preventing changes in the headspace gases on day 11 and in lipid oxidation on all the sampling days. In conclusion, the Chitoex coating could be useful for prolonging the storage of pork burgers by preventing changes in texture and reducing lipid oxidation.