• The Effect of Organic Acid, Trisodium Phosphate and Essential Oil Component Immersion Treatments on the Microbiology of Cod (Gadus morhua) during Chilled Storage

      Smyth, Conor; Brunton, Nigel P.; Fogarty, Colin; Bolton, Declan; Department of Agriculture Food and the Marine; 13F458 (MDPI, 2018-12-08)
      Spoilage is a major issue for the seafood sector with the sale and exportation of fish limited by their short shelf-life. The immediate and storage effects of immersion (30 s at 20 °C) with 5% (w/v) citric acid (CA), 5% (v/v) lactic acid (LA), 5% (w/v) capric acid (CP) and 12% trisodium phosphate (TSP) (experiment 1) and essential oil components (EOC) (1% (v/v) citral (CIT), 1% (v/v) carvacrol (CAR), 1% (w/v) thymol (THY) and 1% (v/v) eugenol (EUG)) (experiment 2) on the concentrations of indicator (total viable counts (TVC) (mesophilic and psychrophilic) and total Enterobacteriaceae counts (TEC)), and spoilage organisms (Pseudomonas spp., lactic acid bacteria (LAB), Brochothrix thermosphacta, Photobacterium spp. and hydrogen sulphide producing bacteria (HSPB)) on cod (Gadus morhua) (stored aerobically at 2 °C) was investigated. There was no significant reduction for most treatment-bacteria combinations, with the following exceptions; TSP and TVCm (time t = 6), TSP and TVCp (t = 6), CP and LAB (t = 6, 8 and 10), CP and Br. thermosphacta (t = 4, 6, 8, 10, 14 and 16), TSP and Photobacterium spp. (t = 4), CAR and Br. thermosphacta (t = 6) and CAR and HSPB (t = 3, 6, 9, 12, 15 and 18). Although the majority of treatments did not significantly (P > 0.05) reduce bacterial counts, the limited success with CP and CAR warrants further investigation.
    • Sensory and ATP derivative-based indicators for assessing the freshness of Atlantic salmon (Salmo salar) and cod (Gadus morhua)

      Fogarty, Colin; Smyth, Conor; Whyte, Paul; Brunton, Nigel; Bolton, Declan; Department of Agriculture, Food and the Marine; 13F458, (Teagasc, 2019-10-31)
      Irish Journal of Agricultural and Food Research | Volume 58: Issue 1 Sensory and ATP derivative-based indicators for assessing the freshness of Atlantic salmon (Salmo salar) and cod (Gadus morhua) Colin Fogarty , Conor Smyth , Paul Whyte , Nigel Brunton and Declan Boltonemail DOI: https://doi.org/10.2478/ijafr-2019-0008 | Published online: 31 Oct 2019 PDF       Abstract Article PDF References Recommendations Abstract To estimate the shelf life of fresh fish, the processor must know the period of time between catch/harvest and arrival at the processing plant. This information is not always available, necessitating the provision of methods to estimate the time since catch or harvest. The objectives of this study were therefore to develop and/or validate sensory and ATP derivative-based methods for rapidly assessing the freshness of fish. A quality index method (QIM; raw fish) and a quantitative descriptive analysis (QDA; cooked fish) were developed and validated (against bacterial count [total viable count (TVC)] and time) for salmon (Salmo salar) and cod (Gadus morhua). The production of inosine monophosphate (IMP), inosine and hypoxanthine (Hx) and associated ratios (IMP/Hx, K1-value or H-value) were also investigated for use as freshness markers. There was a linear relationship between QIM and TVC (R2 = 0.93 for salmon and R2 = 0.89 for cod), QIM and time (R2 = 0.96 for salmon and R2 = 0.98 for cod), QDA and TVC (R2 = 0.93 for salmon and R2 = 0.77 for cod) and QDA and time (R2 = 0.94 for salmon and R2 = 0.87 for cod), suggesting that the QIM and QDA schemes developed could be used to monitor/assess freshness. The H-value also increased linearly with TVC (R2 = 0.88 for salmon and R2 = 0.89 for cod) and time (R2 = 0.93 for salmon and R2 = 0.84 for cod). It was therefore concluded that both the QIM/QDA approach and monitoring ATP degradation, specifically expressed as the H-value, could be used as rapid methods to assess the freshness of salmon and cod arriving at the processing plant
    • Spoilage indicator bacteria in farmed Atlantic salmon (Salmo salar) stored on ice for 10 days

      Fogarty, Colin; Whyte, Paul; Brunton, Nigel; Lyng, James; Smyth, Conor; Fagan, John; Bolton, Declan; Department of Agriculture, Food and the Marine; 13F458 (Elsevier, 2018-08-02)
      This study investigated the growth of indicator and spoilage bacteria on whole Atlantic salmon (Salmo salar) stored aerobically at 2 °C. On days 0, 2, 3, 6, 8 and 10 microbiological analysis was carried out on inner flesh and outer skin samples as well as outer skin swabs (25 cm2 surface areas). Mesophilic total viable counts (TVCm) on skin, flesh and swab samples increased from 1.9, 1.1 and 2.7 log10 CFUcm2 to 6.0, 5.1 and 5.7 log10 CFU/cm2 after 10 days, respectively. Psychrotrophic counts (TVCp), increased from 2.2, 1.8 and 3.1 log10 CFU/cm2 to 6.2, 5.3 and 5.9 log10 CFU/cm2, for skin, flesh and swab samples respectively. Hydrogen sulphide producing bacteria (HSPB), lactic acid bacteria (LAB), Pseudomonas spp., Brochothrix thermosphacta and Photobacterium spp. grew well with similar growth rates (mean generation times of 17.2–26 h). It was concluded that the shelf-life of salmon at 2 °C was approximately 10 days and that HSPB, LAB, Pseudomonas spp., Br. thermosphacta and Photobacterium spp. may be a better indicator of fish spoilage rather than TVC growth, with a count of 5–6 log10 CFU/cm2 indicating the end of shelf-life.