Biochemistry of myoglobin. VI. The effects of low dosage gamma irradiation on beef myoglobin

Improving ground beef safety and stabilizing color during irradiation using antioxidants, reductants or TSP

The objective of this research was to extend ground beef retail display life using antioxidants, reductants, and/or TSP treatments combined with electron beam irradiation. Ground beef was produced with added butylated hydroxyanisole (BHA) plus butylated hydroxytoluene (BHT) with the following combinations; (1) ascorbate; (2) trisodium phosphate(buffer); (3) erythorbate; (1) and (2); (1) and (3); (1), (2), and (3); and an untreated control, C. Half of the treated samples were irradiated (I) at 2.0kGy-absorbed dose under a nitrogen atmosphere, half remained non-irradiated (N). Samples were displayed under atmospheric oxygen and evaluated for total aerobic plate count (TPC), thiobarbituric acid reactive substances (TBARS) and instrumental color during 9d of simulated retail display (SRD). Controls had the highest (P<0.05) TBARS value and the lowest (P<0.05) redness (CIE a∗), proportion of oxymyoglobin and vividness. Treated irradiated samples were just as red and vivid on SRD day 9 as the non-irradiated untreated control at day 0. Treatments stabilized color and lipids of ground beef after irradiation and during SRD.

Effect of electron beam irradiation on poultry meat safety and quality

The purpose of this study was to determine the effectiveness of electron beam irradiation at doses of 1.0 and 1.8 kGy on the elimination of bacteria from boneless, skinless chicken breasts without significantly altering product quality. Microbial testing was conducted in triplicate using a whole carcass rinse method with each nonirradiated control group and an irradiation treatment group consisting of 10 samples. Results indicated that mean counts for coliforms, generic Escherichia coli, and psychrotrophs were 3.13, 3.26, and 1.92 log10 cfu/200 mL rinsate, respectively, in the control samples. However, these populations were not detected after the samples were irradiated with 1.0 or 1.8 kGy. Mean count of 4.60 log10 cfu/200 mL rinsate was detected for aerobic bacteria in the control samples. Irradiation doses of 1.0 and 1.8 kGy reduced the levels to 2.23 and 1.62 log10 cfu/200 mL rinsate, respectively. Irradiation also rendered the fillets free of Salmonella and Campylobacter. Consumer taste panels (product stored for 0, 14, and 28 d at 0 C) indicated that, at Day 0, there were no differences among controls and treatment groups for any of the quality attributes tested. At Day 14, texture and flavor attributes were lower for the irradiated groups. At Day 28, samples irradiated with 1.0 and 1.8 kGy were less desirable with decreased texture, flavor, and overall acceptability. Degree of lipid oxidation also increased as storage time and level of irradiation increased. Irradiated samples also had higher a* values, indicating they were pinker in color.

Effects of ionizing radiation on nitric oxide myoglobin. Part 1. Effects on the NO-haem moiety

Bovine nitric oxide myoglobin (NOMb) was irradiated with 40-4000 krad of gamma-radiation, and the effects on the haem studied using absorption spectroscopy and electron spin resonance (e.s.r.) spectroscopy. The results show the following behaviour. The bright red colour of NOMb changes to brown upon irradiation. This is similar to changes observed in radiation sterilized. nitrite-containing meats. NOMb becomes progressively denitrosylated, with met-myoglobin (metMb) as the immediate product. Upon increasing doses of radiation (up to 800 krad) at 0 degrees C parallel to NOMb denitrosylation, metMb is gradually converted, by water radiolytic products, to other products, believed to be ferromyoglobin and ferrimyoglobin peroxide. A minor quantity of 'choleglobin-type' pigments may also be formed at the highest doses. Freezing of NOMb has a substantial protective effect against radiation. Native bovine NOMb behaves as a pentaco-ordinate (hfs of 3 peaks with equal intensity); the bond between iron and N epsilon is thus dramatically stretched and weakened. Using a thermal energy analyser, no NO could be detected over irradiated NOMb solution, indicating rapid reaction of NO liberated from NOMb by radiation, with radiolytic products of water.