Chitosan dipping or oregano oil treatments, singly or combined on modified atmosphere packaged chicken breast meat.

The present study examined the effect of natural antimicrobials: chitosan, oregano and their combination, on the shelf-life of modified atmosphere packaged chicken breast meat stored at 4°C. Treatments examined in the present study were the following: M (control samples stored under modified atmosphere packaging), M-O (samples treated with oregano oil 0.25% v/w, stored under MAP), M-CH (samples treated with chitosan 1.5% w/v, stored under MAP) and M-CH-O (treated with chitosan 1.5% w/v and oregano oil 0.25% v/w, stored under MAP). Treatment, M-CH-O, significantly affected mesophilic Total Plate Counts (TPC), lactic acid bacteria (LAB), Brochothrix thermosphacta, Enterobacteriaceae, Pseudomonas spp., and yeasts-moulds during the storage period. Lipid oxidation (as determined by MDA values) of control and treated chicken samples was in general low and below 0.5 mg MDA/kg, showing no oxidative rancidity during the storage period. Addition of chitosan to the chicken samples produced higher (P<0.05) lightness (L*) values as compared to the control samples. The results of this study indicate that the shelf-life of chicken fillets can be extended using, either oregano oil singly, and/or chitosan, by approximately 6 (M-O) and >15 (M-CH and M-CH-O) days. Interestingly, chitosan (M-CH) or chitosan-oregano (M-CH-O) treated chicken samples were sensorially acceptable during the entire refrigerated storage period of 21 days. It is noteworthy that the presence of chitosan in M-CH and M-CH-O samples did not negatively influence the taste of chicken samples, with M-CH samples receiving a higher score (compared to M-CH-O), probably as a result of a distinct and "spicy" lemon taste of chitosan, that was well received by the panelists. Based primarily on sensory data (taste attribute) M-CH and M-O treatments extended the shelf-life of chicken fillets by 6 days, while M-CH-O treatment resulted in a product with a shelf-life of 14 days, maintaining acceptable sensory characteristics.

Combined natural antimicrobial treatments on a ready-to-eat poultry product stored at 4 and 8°C.

The aim of the present study was to evaluate the effect of natural antimicrobial agents EDTA, lysozyme, and 2 essential oils (rosemary and oregano) on the quality of a ready-to-eat poultry product (semicooked coated; SCC) stored under aerobic packaging conditions at 4°C (retail) and 8°C (abuse) for a period of 16 d. Treatments included the following: air-packaged chicken fillets (control, untreated); with EDTA (1.50% wt/wt); with lysozyme solution (1.50% wt/wt); with rosemary oil (0.20% vol/wt); with oregano oil (0.20% vol/wt); with a combination of EDTA and lysozyme solutions (1.50% wt/wt each); and with the combination of EDTA, lysozyme, and either rosemary or oregano essential oils (all added at concentrations previously mentioned). The shelf life of the SCC samples (untreated and treated) was determined using both microbiological and sensory analyses. Natural antimicrobial combinations consisting of EDTA, lysozyme, and rosemary or oregano essential oil affected the growth of Pseudomonas and yeasts and molds, whereas EDTA, lysozyme, and rosemary essential oil controlled Brochothrix thermosphacta population in the SCC chicken fillets stored at 4 and 8°C. The combination of EDTA, lysozyme, and either rosemary or oregano resulted in a shelf life extension of 5 d compared with the control samples at both 4 and 8°C, with the former combination producing a more sensorially acceptable product.

Combined chitosan-thyme treatments with modified atmosphere packaging on a ready-to-cook poultry product.

In the present study, natural antimicrobials chitosan and thyme, and their combination, were evaluated for their effect on the shelf life of a ready-to-cook (RTC) chicken-pepper kebab (skewer) stored under modified atmosphere packaging (MAP) conditions at 4 +/- 0.5 degrees C for 14 days. The following treatments were examined: control samples stored under aerobic packaging (A), samples stored under MAP (M), samples treated with 1.5% chitosan (vol/wt) and stored under MAP (M-CH), samples treated with 0.2% thyme essential oil (vol/wt) (M-T), and samples treated with 1.5% chitosan (vol/wt) and 0.2% thyme essential oil (vol/wt) and stored under MAP (M-CH-T). Treatment M-CH-T significantly affected aerobic plate counts and counts of lactic acid bacteria, Pseudomonas spp., Brochothrix thermosphacta, Enterobacteriaceae, and yeasts and molds during the entire storage period. Similarly, lipid oxidation of the RTC product was retarded (M-CH-T treatment) during storage, whereas redness was maintained in M-T, M-CH, and M-CH-T samples. Based primarily on sensory data (taste attribute), M-CH and M-T treatments extended RTC product shelf life by 6 days, whereas M-CH-T treatment resulted in a product with a shelf life of 14 days that maintained acceptable sensory characteristics (shelf life of the control was 6 days).

Combined effects of salting, oregano oil and vacuum-packaging on the shelf-life of refrigerated trout fillets.

The present study evaluated the effect of salt, oregano essential oil (EO) and packaging on fresh rainbow trout fillets during storage at 4 degrees C. Treatments included the following: A1 (control samples, unsalted: air packaged), A2 (salted: air packaged), VP1 (salted, vacuum packaged), VP2 (salted, vacuum packaged with added oregano EO 0.2% v/wt), and VP3 salted, vacuum packaged with added oregano EO 0.4% v/wt). Lactic acid bacteria (LAB) (to a greater extent), followed by H(2)S-producing bacteria (including Shewanella putrefaciens), Pseudomonas spp. and Enterobacteriaceae reached higher populations in A1, A2 (as compared to VP1, VP2 and VP3) trout samples. Treatments VP1, VP2 and VP3 produced significantly lower (P < 0.05) total volatile basic nitrogen (TVBN) and trimethylamine nitrogen (TMAN) values as compared to the A1 and A2 samples after day 6 and until end of storage period. Changes in thiobarbituric acid values (TBA) values for A1, A2, VP1, VP2 and VP3 samples were variable, indicative of no specific trend in trout samples, irrespective of packaging in the absence and/or presence of salt and oregano EO. As determined by sensory analysis (overall acceptability attribute) the observed shelf-life of trout fillets was longest for VP2 (16-17 days) followed by VP1 (14 days), A2 (8 days) and control (A1) samples (5 days). The presence of salt and oregano oil (0.2%) in cooked VP1 trout samples produced a distinct but sensorially acceptable pleasant odor, well received by the panellists, in contrast to the combined effect of salt and oregano oil at the higher concentrations (0.4% v/wt) used. Addition of salt (treatment VP1) extended the product's shelf-life by 9 days, whereas the combination of salt, oregano EO (0.2% v/wt) under VP conditions (treatment VP2) resulted in a significant shelf-life extension of trout fillets (11-12 days) according to sensory data, as compared to the control sample, kept under aerobic conditions.

Effect of chitosan and thyme oil on a ready to cook chicken product.

The present study examined the effect of natural antimicrobials: chitosan, thyme and their combination, on the shelf-life of a Ready to Cook (RTC) chicken-pepper kebab (skewer) stored under aerobic conditions at 4 +/- 0.5 degrees C for a period of 12 days. Treatments examined in the present study were the following: A (control samples, untreated), A-CH (chitosan; 1.5% v/w), A-T (thyme essential oil; 0.2% v/w) and A-CH-T (chitosan; 1.5% v/w and thyme essential oil; 0.2% v/w). The shelf-life of the samples was determined using both microbiological and sensory analyses. Among the microorganisms examined, pseudomonads were the most resistant group towards the combined application of chitosan and thyme oil (ca. 1.5 log cycle reduction) while Lactic acid bacteria (LAB), Brochothrix thermosphacta and Enterobacteriaceae were the most sensitive to the combined action of these two agents (2-3 log cycle reduction). Yeasts-moulds were also part of the natural microbial association of the RTC product, with A-CH-T treatment suppressing effectively their growth during the entire period of storage. Treatments A-CH and A-CH-T resulted in lower pH values as compared to the control (A) samples. Of the treatments examined in the present study, A-CH-T, gave a "spicy", desirable and pleasant (organoleptically acceptable) RTC product. Based primarily on sensory data (taste attribute) A-CH, A-T and A-CH-T treatments extended the product's shelf-life by ca. 4 and 6 days, respectively, as compared to the control sample.

Potential of oregano essential oil and MAP to extend the shelf life of fresh swordfish: a comparative study with ice storage.

The present study evaluated the effect of modified atmosphere packaging (MAP, 5% O(2)/50% CO(2)/45% N(2); treatment M), the addition of oregano oil (0.1%, v/w; treatment AO) as a natural preservative, as well as their combination (treatment MO) on the quality and shelf life extension of fresh Mediterranean swordfish fillets during a refrigerated storage (4 degrees C) period of 18 d. Simultaneously, swordfish fillets were stored under aerobic conditions (control treatment A, 4 degrees C) and on ice (usual commercial method of preservation, treatment I, 0 degrees C). Among the 5 treatments examined in the present study, the most effective one to inhibit the microbial and sensory spoilage proved to be the MO treatment, achieving a shelf life extension of 8 to 9 d. The dominant bacteria in the microflora of swordfish, irrespective of treatment, were the Pseudomonads and the H(2)S-producing bacteria, while both lactic acid bacteria (LAB) and the Enterobacteriaceae produced the lowest populations in swordfish samples kept on ice. Among the chemical indices examined, thiobarbituric acid (TBA) values showed no specific trend of lipid oxidation for swordfish, irrespective of treatment. Final trimethylamine nitrogen (TMA-N) and total volatile basic nitrogen (TVB-N) values for treatments, A, AO, M, and MO ranged between 1.33 and 14.29 mg N/100 g and 14.11 to 55.52 mg N/100 g, respectively, whereas for I samples they remained almost unchanged during storage. Sensory analysis (taste attribute) correlated well with microbiological analysis, indicating a shelf life of approximately 5 to 6 d for control, 10 to 11 d for AO, 12 d for I, 13 d for M, and 14 d for MO samples.