Low Dose Irradiation Affects Microbiological and Sensory Quality of Sub‐Tropical Seafood

Abstract

Irradiation treatmentSweetlip (Lethrinus miniutu.s), red emperor (LZ@IU.S sebae), mackerel (Scomberomorus commerson), whiting (Sillago ciliutu), mullet (Mu@ cephulus), barramundi (Lutes culcurzfer), sand crab (Portunus pelugicus), Moreton Bay prawns (Metupenueus spp. ) and king prawns (Penueusplubujus) were irradiated at doses of 0, 1, 3 and 5 kGy. A dose of 1 kGy resulted in a 1.5 to 4 log reduction in total bacterial numbers. Sensory quality decreased with increasing radiation dose except for Moreton Bay prawns and cooked king prawns, which were acceptable after a 5 kGy dose. Doses higher than 3 kGy caused adverse odor and flavor changes in Moreton Bay and cooked king prawns. A dose of 1 kGy could extend storage life of any of the species without adversely affecting sensory quality.Seafood packs were stored in crushed ice within insulated containers and irradiated in a small batch plant with a %o plaque source (Izard, 1985) within 24 hr of purchase. The source had an activity of 69,000 curies. Seafood was given a 0, 1, 3 or 5 kGy irradiation dose at a dose rate of 7.2 Gy/min as determined by ceric-cerous sulphate dosimetry. These doses were minimum in all cases (minimum to maximum ratios < 1:1.3). Temperature of the seafoods remained at 2°C throughout irradiation. Following irradiation, one pack of each seafood from each treatment was randomly selected and held chilled. All other packs were immediately blast frozen (-40°C) for subsequent sensory evaluation. All evaluations were completed within 3 wk of irradiation.

Radiation Processing to Improve the Quality of Fishery Products

“…163,303 Radurization processes have been developed for a variety of fishery products, including marine fish, freshwater fish, and shellfish. 113,207,219,238,239,259 These are summarized in Tables 3 and 4. The extension in shelf life due to irradiation depends on several factors, including initial quality of the fish, irradiation dose, packaging conditions, and storage temperature.…”

“…These arise from qualitative and quantitative changes in the microbial growth and radiation dose responses of tissue constituents that govern the organoleptic attributes of fishery products. Radiation-sensitive Gram-negative bacteria are mostly responsible for spoilage of fishery products; 11,108,219,223,239,240,245,255,259 therefore, reduction of spoilage-causing microorganisms by a low level of radiation leads to an extension in shelf life of the fishery products.…”

Impact of Irradiation on Fish and Seafood Shelf Life: A Comprehensive Review of Applications and Irradiation Detection

“…Only the pomfret skin exhibited skin oxidation after treatment and this value continued to rise throughout storage (Doke et al, 1992). Poole et al (1994) irradiated Sweetlip (Lethrinus miniatus), red emperor (Lutjanus sebae), mackerel (Scomberomorus commerson), whiting (Sillago ciliate), mullet (Mugil cephalus), barramundi (Lates calcalifer), sand crab (Portunus pelagicus), Moreton Bay prawns (Metapenaeus spp), and king prawns (Penaeus plubujus) with 0, 1, 3, and 5 kGy. All samples were stores in crushed ice.…”

Alimentos irradiados

“…Se han observado pérdidas de la vitamina tiamina poco importantes a dosis de 1 kGy, con la que se obtiene una disminución importante de microorganismos sin afectar a las características organolépticas (Ming-Sai Liu et al 1991). Para especies subtropicales se recomienda el tratamiento a 1 kGy como óptimo por las características sensoriales y de conservación que se obtienen, mientras que el límite máximo de dosis es de 3 kGy debido a la aparición de cambios organolépticos indeseables (Poole et al 1994). Idénticos resultados se han obtenido más recientemente para merluza (Silva et al 1994).…”

“…La dosis a utilizar vendrá dada por el alimento a tratar y el efecto que queremos obtener (Tabla 2). Murray, 1983Fiszer et al 1 985 Matin et al 1985Lastarria-Tapia y Sequeiros, 1985Farkas, 1998Grant y Patterson, 1991bBoisseau, 1994Poole et al 1994Rashid et al 1992Kume et all987 Katusim-Razem et al 1985Johnson y Marcotte, 1999Koomhof et al 1994 La dosis máxima a utilizar vendrá limitada por el mantenimiento óptimo de la calidad del alimento irradiado (Camcigil, 1991).…”