• Adding Value To Under utilised Fish Species

      Fagan, John; Gormley, Ronan T.; Mitchell, Michelle; Downey, Gerard (Teagasc, 2006-02-01)
      Tightening fish quotas and supply shortages for conventional species are causing major difficulties for both fishermen and seafood processors. There is a need, therefore, to explore the potential of underutilised fish species both as fillets or portions and as added-value products. The current project at Ashtown Food Research Centre (AFRC) addressed this issue for a number of underutilised species via (a) sous vide processing (with savoury sauces),(b)marinating (salt- and sugar-based marinades) and (c) via a combination of freeze-chilling and modified atmosphere packaging (MAP).A range of physico-chemical and sensory tests was conducted on the products and their shelf-life status was also determined.
    • Adding value to under-utilised fish species

      Fagan, John; Gormley, Ronan T.; Mitchell, Michelle; Downey, Gerard (Teagasc, 2006-02)
      Tightening fish quotas and supply shortages for conventional species are causing major difficulties for both fishermen and seafood processors. There is a need, therefore, to explore the potential of underutilised fish species both as fillets or portions and as added-value products. The current project at Ashtown Food Research Centre (AFRC) addressed this issue for a number of underutilised species via (a) sous vide processing (with savoury sauces),(b)marinating (salt- and sugar-based marinades) and (c) via a combination of freeze-chilling and modified atmosphere packaging (MAP).A range of physico-chemical and sensory tests was conducted on the products and their shelf-life status was also determined.
    • Comparison of rapid laboratory tests for failure of passive transfer in the bovine

      Hogan, Ian; Doherty, Michael; Fagan, John; Kennedy, Emer; Conneely, Muireann; Brady, Paula; Ryan, Clare; Lorenz, Ingrid (Biomed Central, 2015-08-25)
      Background Failure of passive transfer of maternal immunity via colostrum can occur in the bovine, and a number of blood tests have been developed to test calves for this failure. It is not clear which test is most suitable for this purpose. The objective was to examine the most commonly used tests for failure of passive transfer and to decide which is most suitable for routine laboratory use. 126 serum samples were taken from calves of dairy cows after birth but prior to colostrum feeding, and at 48 h of age. Five different tests were compared against radial immunodiffusion which is considered the appropriate reference method. These tests were serum gamma-glutamyltransferase levels, serum protein levels, serum globulin levels, an enzyme linked immunosorbent assay and the zinc sulphate turbidity test. Results The tests examined displayed high sensitivity but widely varying specificity. Examination of the use of different cut-off points allowed some improvement in specificity at the expense of sensitivity, but the tests which had performed best at the original cut-off points still displayed the best performance. Gamma-glutamyltransferase levels as a measure of colostrum absorption returned, in this study, the best balance between sensitivity and specificity. The ELISA used in this study and serum globulin levels displayed performance similar to the gamma-glutamyltransferase levels. Serum total protein was less successful than others examined at providing both sensitivity and specificity but may, when performed via refractometer, be useful for on-farm testing. As currently performed the poor sensitivity for which the zinc sulphate turbidity test is most often criticized is evident. Modification of the cut-off point to increase specificity is less successful at balancing these parameters than the ELISA, gamma-glutamyltransferase levels, and globulin levels. Conclusions Gamma-glutamyltransferase levels, ELISA testing and circulating globulin levels performed best in detecting failure of passive transfer in serum samples, although all three had some practical considerations.
    • Freeze-chilling and gas flushing of raw fish fillets

      Fagan, John; Gormley, Ronan T.; Uí Mhuircheartaigh, Mary M. (Teagasc, 2003-04)
      Freeze-chilling involves freezing and frozen storage followed by thawing and chilled storage. Trials with whiting and mackerel fillets/portions (Part 1) indicated no difference in odour scores (raw samples) between freeze-chilled and chilled samples; however, freeze-chilled salmon portions were inferior to chilled in terms of odour. Fresh fillets received the highest acceptability scores as cooked samples followed by frozen, chilled and freeze-chilled fillets. Freshness indicators were the same for the three species. Freeze-chilled fillets had the highest free fatty acid and peroxide values but the levels were low and did not influence sensory response. The effects of the four treatments on the colour and texture of the raw fillets were small in practical terms and typical shelf-lives in the chill phase of the freeze-chill process were 3 to 5 days. In Part 2, modified atmosphere packaging (MAP) was combined with freezechilling to further extend the shelf-life of raw whiting, mackerel and salmon fillets/portions. Typical shelf-lives in the chill phase for the freeze-chilled fillets were 5 (whiting and mackerel) and 7 (salmon) days. Good manufacturing practice coupled with HACCP and careful tempering (thawing) are essential for the successful freeze-chilling of raw fish fillets. Packs should be labelled ‘previously frozen’ for consumer information. It is concluded that freeze-chilling with MAP is a suitable technology for extending the shelf-life of raw fish fillets.