Table 4.
Growth parameters (initial lag period, mean generation time and maximum growth rate (µmax)) of mesophilic total viable count (TVCm), psychrophilic total viable count (TVCp), total Enterobacteriaceae (TEC), Pseudomonas spp., lactic acid bacteria (LAB), Br. thermosphacta, Photobacterium spp. and hydrogen sulphide producing bacteria (HSPB) on cod treated with sterile distilled water (SDW), 5% (w/v) citric acid (CA), 5% (v/v) lactic acid (LA), 5% (w/v) capric acid (CP) or 12% (w/v) trisodium phosphate (TSP) and stored aerobically at 2 °C for 18 days.
| Bacteria | Initial Lag Time (h) | Mean Generation Time (h) 1 | µmax (Generations h−1) | |||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| CTL 2 | SDW | CA | LA | CP | TSP | CTL | SDW | CA | LA | CP | TSP | CTL | SDW | CA | LA | CP | TSP | |
| TVCm | NA 3 | NA | NA | NA | NA | NA | 18.9 | 12.8 | 23.3 | 18.0 | 23.0 | 20.3 | 0.05 | 0.08 | 0.04 | 0.06 | 0.04 | 0.05 |
| TVCp | NA | NA | NA | NA | NA | NA | 15.6 | 14.2 | 16.8 | 19.2 | 15.0 | 18.9 | 0.06 | 0.07 | 0.06 | 0.05 | 0.07 | 0.05 |
| TEC | NA | NA | 26.1 | 20.0 | 24.7 | NA | 51.8 | 63.7 | 44.9 | 40.6 | 46.2 | 46.8 | 0.02 | 0.02 | 0.02 | 0.02 | 0.02 | 0.02 |
| Pseudomonas spp. | NA | NA | NA | NA | NA | NA | 15.0 | 15.2 | 14.4 | 18.7 | 15.2 | 15.8 | 0.07 | 0.07 | 0.07 | 0.05 | 0.07 | 0.06 |
| LAB | 15.6 | NA | 59.3 | 25.3 | 103.7 | 68.6 | 27.8 | 30.9 | 26.2 | 21.9 | 36.6 | 14.6 | 0.04 | 0.03 | 0.04 | 0.05 | 0.03 | 0.07 |
| Br. thermosphacta | NA | NA | NA | NA | 82.9 | 1.82 | 16.6 | 17.0 | 17.8 | 18.5 | 96.6 | 14.9 | 0.06 | 0.06 | 0.06 | 0.05 | 0.07 | 0.07 |
| Photobacterium spp. | NA | NA | 25.0 | NA | 28.2 | 47.5 | 17.8 | 17.4 | 18.7 | 15.9 | 16.2 | 17.3 | 0.06 | 0.06 | 0.05 | 0.06 | 0.06 | 0.06 |
| HSPB | NA | NA | NA | NA | NA | NA | 15.1 | 12.0 | 18.8 | 25.9 | 16.1 | 12.7 | 0.07 | 0.08 | 0.05 | 0.04 | 0.06 | 0.08 |
1 Calculated using the formula G = t/3.3 logb/B, where t = time interval in h to when the late lag phase was reached, b = number of bacteria at the end of the time interval, and B = number of bacteria at the beginning of the time interval [27]. 2 CTL = untreated control. 3 NA = not applicable as the bacteria were in the log phase of growth at time t = 0. The mean bacterial (TVCm, TVCp, TEC, Pseudomonas spp., LAB, Br. thermosphacta, Photobacterium spp. and HSPB) counts on cod treated with 1% (v/v) CIT, 1% (v/v) CAR, 1% (w/v) THY and 1% (v/v) EUG and stored at 2 °C are shown in Table 5. The corresponding growth parameters (initial lag period, mean generation time and maximum growth rate) are shown in Table 6. TVCm and TVCp counts were statistically similar (P > 0.05) to the control at each sampling time, regardless of treatment. Similarly, the other bacterial counts (TEC, Pseudomonas spp., LAB, Br. thermosphacta, Photobacterium spp. and HSPB) were not significantly different (P > 0.05) to the control within the bacterial groups with the following exceptions; Br. thermosphacta with CAR (t = 6) and HSPB with CAR (t = 3, 6, 9, 12, 15 and 18).