Effects of stunning duration on quality characteristics of early deboned chicken fillets

The effects of electrical and controlled atmosphere stunning methods on meat and liver quality of geese

The objective of this research was to investigate the effects of electrical and gas stunning on the meat and liver quality characteristics of liver geese. Sixty birds were slaughtered at 12 wk of age, in groups of 20 at three different times. Thirty birds each were subjected to one of the two stunning methods. Deboned breast fillets and thigh muscles were evaluated for hemorrhaging, amount of blood in the veins, and color by using a visual grading system. Livers were removed from carcasses during evisceration and were subsequently graded. Besides external color and hemorrhaging, the degree of liver weight loss due to removal of blood vessels was also determined. The use of controlled atmosphere stunning significantly reduced the incidence of muscle hemorrhages when compared to electrical stunning. However, no significant difference was found for color or amount of blood remaining in the veins of muscles between geese receiving electrical or controlled atmosphere stunning. The hemorrhaging and color scores of livers from gas-stunned birds did not differ from those of electrically stunned birds. As for the liver weight loss caused by removal of veins and capillaries, stunning treatment had no significant effect on this parameter. These results suggest that controlled atmosphere stunning produced slightly better quality goose meat but did not improve liver quality when compared to the electrical stunning method used.

Effect of electrical stimulation and polyphosphate marination on drip from early-harvested, individually quick-frozen chicken breast fillets

Individual and combined effects of electrical stimulation and polyphosphate marination on drip and other quality attributes of early-harvested, individually quick-frozen chicken breast fillets were evaluated. Broiler chickens were slaughtered, half conventionally processed and half with electrical stimulation. Fillets were harvested 1 h postmortem and marinated in either NaCl solution or NaCl plus polyphosphate solution. Marinade absorption, pH, drip, cooking loss, and shear values were observed. Electrical stimulation had no direct effect on pH, cooking loss, or shear values, whereas polyphosphate increased pH and decreased cooking loss. Polyphosphate treatment caused fillets from unstimulated carcasses to absorb more marinade and yielded more drip that those from stimulated carcasses. Fillets from stimulated carcasses marinated in NaCl solution without polyphosphate yielded less drip than those from unstimulated carcasses. Polyphosphate reduced drip of fillets from unstimulated carcasses but not of those from stimulated carcasses. Results support previous reports indicating interactions between polyphosphates and processing parameters that can affect ultimate quality of poultry meat products.

Meat quality during processing

The study of growth and development of any food animal such as poultry needs to consider the effects of the muscle changes on the use of the muscle as meat. If a treatment could increase muscle growth but the increased meat was of poor quality, then the increase in production would be of little value. Muscle is of particular concern because not only is it the tissue of greatest value for food, but it also is an excitable tissue and responsive to its environment. Many of these responses can be quite deleterious to meat quality. The basis for the response of muscle to its environment is in postmortem metabolism and the simultaneous development of rigor mortis. Although the animal may die in a matter of minutes following the neck cut, its muscle cells continue to metabolize and respond for hours after respiratory cessation and brain death. During these hours, the muscle has energy that fuels the responses to the environment, most commonly in terms of color and texture. Heat, transportation, and handling all contribute to the preslaughter stress that can alter color, texture, and related protein functionality. Stunning is another preslaughter factor that has a large effect on postmortem metabolism and meat quality. After death, chilling can toughen meat while it adds juiciness, and aging prevents the meat from toughening in response to deboning. Electrical stimulation is a recent beneficial innovation that reduces the need for aging by accelerating postmortem energy depletion and reducing the muscle's ability to toughen during deboning. This paper reviews the responsiveness of the muscle and gives examples of how these responses can hurt or help meat quality.

Effect of polyphosphate treatment and electrical stimulation on postchill changes in quality of broiler breast meat

The objective of this study was to assess effects of treating electrically stimulated broiler forequarters with polyphosphates after various aging periods on quality. Ninety-six mixed sex broilers were electrically stunned and slaughtered. Half the carcasses were electrically stimulated during bleeding and half were not. Forequarters were harvested immediately after chilling and after 2, 4, and 6 h postchill. Left forequarters were marinated in salt solution and right forequarters in salt solution plus sodium tripolyphosphate. After marination, the quarters were cooked. Yield and meat pH were evaluated immediately after marinating; and color, yield, and cooking loss were evaluated after cooking. Electrical stimulation resulted in a decline in muscle pH for the 0 postchill group. The pH of muscles from unstimulated and stimulated carcasses from the remainder of the postchill times were equivalent. Phosphate treatment increased pH at all postchill times. Electrical stimulation of the marinated quarters increased cooking loss and decreased yield regardless of marinade composition. Both cooking loss and yield were superior for forequarters harvested at 0 or 2 h postchill compared to those harvested at 4 or 6 h postchill. The phosphate improved moisture binding regardless of electrical treatment or time of harvest. Color values of cooked muscles were unaffected by marination time, but the phosphate-treated muscles had higher b* (yellowness) values than controls. Shear values of unstimulated carcasses that received phosphate treatment were 35% greater than those that received no phosphate treatment. When the carcasses were electrically stimulated, the toughening effect of the phosphate was eliminated.