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Severino R.,Competence Center on Agro Food Productions | Severino R.,INRS Institute Armand Frappier | Ferrari G.,Competence Center on Agro Food Productions | Ferrari G.,University of Salerno | And 4 more authors.
Food Control | Year: 2015

The antibacterial activity of modified chitosan-based coatings containing nanoemulsion of essential oils (EOs), gamma irradiation, modified atmosphere packaging (MAP), alone or in combinations, against Escherichia coli O157:H7 and Salmonella Typhimurium was evaluated on inoculated green bean samples. Firstly, four different nanoemulsions, made of carvacrol, mandarin, bergamot and lemon Eos, respectively, were compared in terms of minimum inhibitory concentration (MIC) against the two bacteria evaluated in vitro using the micro-broth dilution method. Carvacrol nanoemulsion resulted to be the most effective antibacterial agent and was therefore selected to be incorporated into modified chitosan (MC) to form a bioactive coating. Secondly, the radiosensitivity of E. coli and S. Typhimurium to gamma irradiation was evaluated on inoculated green beans after coating deposition and MAP. Results showed that, without MAP, MC-based coating containing carvacrol nanoemulsion significantly increased the radiosensitization of E. coli and S. Typhimurium by 1.32-fold and 1.30-fold, respectively. Remarkably, the use of bioactive coating under MAP caused a synergistic effect with an increase in radiosensitivity by 1.80-fold and 1.89-fold for E. coli and S. Typhimurium, respectively. Thirdly, the antibacterial effects of the antimicrobial coating, gamma irradiation, MAP alone and their combinations were evaluated against these two bacteria during a 13-days storage of green beans at 4 °C. Bioactive coating deposition or gamma irradiation treatment resulted effective in controlling the growth of the two bacteria during the entire shelf-life. Moreover, it was also found that the combined treatment of antimicrobial coating, gamma irradiation and MAP caused the reduction of microbial population to undetectable levels during the whole storage period for E. coli and from day 7 to the end of storage for S. Typhimurium. The obtained results can be interested to food companies aiming to ensure the food safety with a prolonged shelf life. © 2014 Elsevier Ltd. Source


Sessa M.,Competence Center on Agro Food Productions | Ferrari G.,Competence Center on Agro Food Productions | Ferrari G.,University of Salerno | Donsi F.,University of Salerno | Donsi F.,Unilever
Chemical Engineering Transactions | Year: 2015

Edible coatings are considered an environmentally friendly technology, able to extend the shelf-life of fruit and vegetables. In the present work, a novel approach to the preservation of vegetable products is proposed, through the development of edible coatings, containing nanoemulsified natural antimicrobial compounds. Modified chitosan was initially selected as film-forming biopolymer, owing to its inherent antimicrobial activity. Different essential oil nanoemulsions, with variable composition, mean droplet size and surface charge, containing lemon, Mandarin, oregano or clove essential oils, were developed to maximize in vitro the interaction with the modified chitosan coating and promote the resulting antimicrobial activity. The combined use of nanoemulsified lemon essential oil with modified chitosan resulted in the remarkable increase in antimicrobial activity, with respect to other essential oils. Therefore, this formulation, comprising 0.05%wt modified chitosan and 0.1%wt nanoemulsified lemon essential oil, was further tested in product for the stabilization of a leaf vegetable, such as rucola, during a shelf-life, consisting of storage at 4°C for 3 d and then at 8°C for a total of 21 d. Microbial viability as well as colour and texture changes were monitored during the shelf-life. The obtained results showed that the incorporation of nanoencapsulated lemon essential oil into the modified chitosan coating prolonged the shelf life of rucola leaves from 3 to 7 d, in comparison to the untreated sample. Moreover, the modified chitosan containing the nanoemulsified antimicrobial caused a significantly longer shelf-life also in comparison to a coating made of modified chitosan or essential oil alone. In conclusion, thanks to this novel treatment it is possible to prolong the shelf life of delicate leaf vegetables to about 10 - 14 d, without causing any significant alteration of the organoleptic properties of the product, preventing the loss of firmness and colour changes and preserving palatability during storage. Copyright © 2015, AIDIC Servizi S.r.l. Source


Severino R.,Competence Center on Agro Food Productions | Severino R.,Canadian Irradiation Center Institute Armand Frappier | Vu K.D.,Canadian Irradiation Center Institute Armand Frappier | Donsi F.,University of Salerno | And 4 more authors.
International Journal of Food Microbiology | Year: 2014

The antimicrobial activity against Listeria innocua of three different combined non-thermal treatments, along with the impact on color and texture on green bean samples, was evaluated. In this study a bioactive coating formulation based on modified chitosan containing 0.05% nanoemulsion of mandarin essential oil was tested in combination with γ-irradiation, UV-C and ozonated water treatments, and the results in terms of antimicrobial activity, color and texture changes, were evaluated during 14. days storage. The combined coating and γ-irradiation treatment gave promising results, showing 3.3 log CFU/g initial microbial reduction, and exhibiting a strong synergistic antimicrobial effect. The treatment based on UV-C and coating formulation allowed a 3 log CFU/g reduction of initial L. innocua population on samples, showing a good residual antimicrobial activity and preventing loss of firmness and color changes during storage. The combined treatment of coating and ozonated water did not show any synergistic or additive antimicrobial effect, but they showed an impact on firmness and color. In conclusion UV-C and γ-irradiation treatments, in combination with the bioactive coating, represent an effective approach to control the growth of L. innocua on vegetable foods. © 2014 Elsevier B.V. Source


Severino R.,Competence Center on Agro Food Productions | Severino R.,Institute of Nutraceutical and Functional Foods | Vu K.D.,Institute of Nutraceutical and Functional Foods | Donsi F.,University of Salerno | And 4 more authors.
Journal of Food Engineering | Year: 2014

The antilisterial effect of three non-thermal treatments in combination with a bioactive coating formulation on broccoli florets inoculated with Listeria monocytogenes was evaluated. The nanoemulsions of carvacrol, bergamot, lemon and mandarin essential oils (EO) were incorporated in native and modified chitosan coating formulations and the antilisterial effect in inoculated samples was evaluated. The modified chitosan based coating containing mandarin EO was the best treatment which caused a load reduction of 1.46 log CFU/g after 6 days of storage. The antilisterial effects of this coating formulation in combination with ozonated water, UV-C and γ-ray treatments on inoculated samples were evaluated during 13 days storage at 4 C. The combined coating and ozonated water showed very high antilisterial effects at days 1 and 3; however, their antilisterial activity was reduced after day 5. The combined coating and UV-C did not show any additive effect against L. monocytogenes as compared to coating alone. The best antilisterial activity was obtained in the combined coating and γ-rays. This combined treatment caused an increase in relative radiation sensitivity of L. monocytogenes by 1.33-fold. Further, this combined treatment ensured microbial safety during storage with a reduction of L. monocytogenes by 2.5 log CFU/g after 13 days. © 2013 Elsevier Ltd. All rights reserved. Source


Donsi F.,University of Salerno | Marchese E.,University of Salerno | Maresca P.,Competence Center on Agro Food Productions | Pataro G.,University of Salerno | And 5 more authors.
Postharvest Biology and Technology | Year: 2015

The combination of an antimicrobial edible coating with other non-thermal treatments, comprising high hydrostatic pressure (HHP) or pulsed light (PL), was assessed against Listeria innocua, inoculated on green bean samples, evaluating also the impact on product color and firmness during 14 days refrigerated storage at 4. °C.The coating formulation consisted of modified chitosan containing a nanoemulsion of mandarin essential oil. Non-thermal treatments conditions were determined in preliminary inactivation tests against L. innocua inoculated on coated green beans, which showed that 400MPa and 5min for HHP, and 1.2×105J/m2 per bean side for PL, were able to cause a reduction in L. innocua population of about 4 and 2Log cycles, respectively.The combination of the coating application with HHP resulted as the most promising approach, causing a significant reduction of L. innocua over the entire storage period, owing to the development of a significant synergism of antimicrobial effects; however, it also had a strong impact on green beans firmness. In contrast, the combination of the coating application with PL exhibited a slight antagonistic effect, and had a slight detrimental impact on color properties. © 2015 Elsevier B.V. Source

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