Irradiated steaks

The effects of seven processing variables which, on the basis of previous literature reports (7, 27) and our chemical studies on model systems, might affect the irradiation flavor intensity or consumer acceptance of irradiated steaks were evaluated in statistically designed and analyzed experiments. Steaks were then prepared using the processing conditions shown to be optimum by these experiments and evaluated for consumer acceptance and storage stability. 

Consumer Acceptance of Irradiation-Sterilized Steaks. To determine the consumer reaction to irradiated steak produced under conditions shown... 

This test indicates that an acceptable irradiated steak product can be prepared and off-flavor caused by irradiation reduced to a point where other quality aspects of the steaks, such as meat quality, cookery, serving conditions, etc., are at least as important as extent of irradiation flavor in determining over-all consumer acceptance. 

Table XI. Irradiation Flavor Intensity Scores (with 95% Confidence Intervals) of Irradiated Steaks Stored at 75°F.

In a recent study in the United States, irradiation of a prepared meal consisting of Salisbury steak, gravy, and mashed potatoes at 5.7 kGy effectively eliminated the background microbial population and high concentrations of L. monocytogenes contamination without causing adverse effects on quality [91]. 

Consumer acceptance was evaluated by panels made up of 75 or more laboratory staff members who had had no recent experience with irradiated products. Panel members were not informed of the nature of the test. Each panelist received one irradiated and one nonirradiated control steak and was asked to rate each sample on over-all acceptability, using a 7-point Hedonic scale with 1.0 equal to dislike very much, 4.0 neither like nor dislike, and 7.0 like very much., Half of the panel members received the irradiated product first, and half received the nonirradiated control first. 

The irradiation flavor scores in Table V show quantitatively the dependence of irradiation flavor intensity on irradiation temperature for both oxygen-packed and vacuum-packed steaks brought to 4°C. rapidly after irradiation. 

Table V. Effect of Irradiation Temperature on Irradiation Flavor Intensity of Steaks Irradiated at 6.0 Megarads...

Slow Warming Rate. Eight cans of steaks packed in an oxygen atmosphere and eight cans of vacuum-packed steaks were held at — 196°C. after irradiation for 96 hours and then allowed to warm slowly in an insulated box, warming from —196° to 4°C. in 31 hours. 

Effect of Packaging Environment. Because of the opposing effects of postirradiation warming rate on steaks packed in an oxygen atmosphere and on vacuum-packed steaks discussed above, it was not possible to establish a clear preference on the basis of initial irradiation flavor intensity scores. 

Optimum Conditions for Preparations of Irradiation-Sterilized Steaks. 

The results of the process variable study reported above, along with our previous study (31) of steak preparation variables, lead us to recommend the processing conditions in Table IX for preparing shelf-stable beefsteaks of maximum acceptability. The processing variables having the greatest effects on irradiation flavor intensity and organoleptic acceptability are... 

Table X. Responses of Consumer Panel to Irradiated (6 Megarads at — 196°C.) and Nonirradiated Steaks Prepared Using Optimum Processing Conditions...

Storage Tests. Steaks prepared using the processing conditions in Table IX were evaluated at intervals in a one-year room temperature (24°C.) storage test. One set of samples taken from a single U. S. Choice round was irradiated to 3.0 megarads at room temperature to serve as internal panel controls. These samples were held at 24°C. for 1 week and then placed in — 20°C. storage. 

Test panel scores over the 12-month test period are shown in Table XI. Since the irradiation flavor scores of the product held at — 20°C. should not change appreciably with time, it appears that the indicated fluctuations in flavor intensity are caused by the taste panel and not by differences in the samples. Some panel evaluation difficulties were experienced with these samples, owing to a variable amount of edge charring which occurred during preparation of the steaks. The texture of these steaks remained good during the test period. 

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