Biomedical subjects
M P Castañeda
Publications and source records attributed to M P Castañeda.
Probiotic alternatives to reduce gastrointestinal infections: the poultry experience.
The intestinal mucosa represents the most active defense barrier against the continuous challenge of food antigens and pathogenic microorganisms present in the intestinal lumen. Protection against harmful agents is conferred by factors such as gastric acid, peristalsis, mucus, intestinal proteolysis, and the intestinal biota. The establishment of beneficial bacterial communities and metabolites from these complex ecosystems has varying consequences for host health. This hypothesis has led to the introduction of novel therapeutic interventions based on the consumption of beneficial bacterial cultures. Mechanisms by which probiotic bacteria affect the microecology of the gastrointestinal tract are not well understood, but at least three mechanisms of action have been proposed: production/presence of antibacterial substances (e.g., bacteriocins or colicins), modulation of immune responses and specific competition for adhesion receptors to intestinal epithelium. The rapid establishment of bacterial communities has been thought to be essential for the prevention of colonization by pathogenic bacteria. Some animal models suggest that the reduction in bacterial translocation in neonatal animals could be associated with an increase in intestinal bacterial communities and bacteriocin-like inhibitory substances produced by these species. This review emphasizes the role of the intestinal microbiota in the reduction of the gastrointestinal infections and draws heavily on studies in poultry.
Skin pigmentation evaluation in broilers fed natural and synthetic pigments.
Broiler carcass skin color is important in the United States and Mexico. This study evaluated the use of natural and synthetic pigments in broiler diets at commercial levels. Birds were fed natural or synthetic pigments at low or high levels, simulating US and Mexican commercial practices. Skin color was measured during live production (3 to 7 wk of age) and after slaughter and chilling. The natural pigments had consistently greater skin b* values (yellowness) than the synthetic pigments. The high levels produced greater skin b* values than the low levels, regardless of source. The synthetic pigments had a slower increase in skin b* but reached the same level as the natural low by 7 wk. There was no difference in skin a* values (redness) due to pigment source or level or the age of the bird. By 7 wk, all pigment sources approached plateau levels in the blood, but the synthetic pigment diet produced higher blood levels of yellow and red pigments than the natural pigment diets. Processing intensified skin yellowness and reduced skin redness. These data suggest that although synthetic pigments might have been absorbed better than natural ones, natural pigments were more efficient at increasing skin yellowness and there were only small differences between high and low levels for each pigment source. This finding may allow reduction in pigment use and feed cost to achieve the same skin acceptance by the consumer.
Research note: Functionality of electrically stimulated broiler breast meat.
Postmortem electrical stimulation (ES) tenderizes meat by acceleration of adenosine triphosphate (ATP) depletion, pH decline, and physical disruption of muscle fibers. It has been demonstrated that rigor development at elevated temperatures, as with slow chilling, can cause meat to develop pale color and poor water-holding capacity. The objective of this study was to compare the functionality of broiler breast meat from control and electrically stimulated carcasses with and without normal rapid chilling. Broilers were either electrically stimulated (450 mA, 450 V, 2 s on, 2 s off for 7 pulses) immediately after bleeding or used as nonstimulated controls. The ES birds were either chilled immediately (ES2) or had chilling delayed for 2 h at room temperature (ESD2). All ES breast fillets were harvested at 2 h postmortem. The control carcasses were chilled immediately and had fillets harvested at 2 h postmortem (C2) or at 8 h postmortem (C8). Electrical stimulation accelerated pH decline and prevented toughening when breast meat was deboned at 2 h postmortem, regardless of chilling rate. The water released from the gels during cooking was higher for the ESD2 than the ES2 group, which was not different from the C2 group, suggesting that ES followed by slow chilling reduced water-holding capacity compared with the ES2 and C2 groups. There were no differences in expressible moisture, gel strength, or lightness among the ES2, ESD2, and C2 treatments. These results indicated that high voltage ES followed by normal chilling did not impair protein functionality or cause pale, soft, exudative meat. However, there was some evidence that slow chilling after ES may negatively affect some water-holding properties of the meat.
Early postmortem carcass trim effects on the tenderness of broiler breast fillets.
Broiler carcasses are often trimmed during evisceration to remove damaged areas of the carcass. Because deboning before rigor mortis development can toughen meat, trimming during evisceration may toughen the meat. This study evaluated the effects of trimming on the tenderness of broiler breast meat. To evaluate the effect of wing removal on tenderness, breast halves from 2 flocks were collected after chilling at a commercial plant. One-third were untrimmed controls, one-third had small amounts of breast meat removed with wing (WMin), and one-third had large amounts of breast meat removed with wing (Wmax). Salvage fillets from the 2 flocks were also collected from the salvage table of the plant. Carcasses were also processed to evaluate the effect of breast blister trimming that removed a superficial amount of muscle tissue, half of which had breast blister trims, and half did not. All front halves or carcasses were aged until 24 h postmortem and deboned. Salvage fillets were held refrigerated until 24 h postmortem. Fillets were cooked and then sheared in 2 locations on the fillet, upper and lower, to determine if tenderness was more affected at areas close to the trim. Carcasses with wing trims had significantly higher shear values compared with the control, and shear values from the upper portion of the fillets from the WMax and WMin (nearer the trim) were significantly greater than for the lower portion. Location, however, did not affect shear values in the control carcasses. This finding indicated that tenderness of the areas nearest the trim might be affected more by the trim process. Salvage table deboning significantly increased shear values throughout the fillet. There was no significant difference in shear value due to breast blister trimming. The results of this study suggest that trimming carcasses by wing or breast fillet removal results in decreased meat tenderness.