Relating induced in situ conditions of raw chicken breast meat to pinking.

Our objective was to simulate the pink color defect in cooked chicken breast meat with treatment combinations that would induce measurable changes in the conditions of raw meat. In addition, the feasibility of using induced raw meat conditions to develop a logistic regression model for prediction of pinking was studied. Approximately 960 breast fillets from 2 plants with 2 replications were used for inducing in situ conditions with 16 combinations of sodium chloride, sodium tripolyphosphate, sodium erythorbate, and sodium nitrite (present and not present). Muscles in all treatments were subjected to individual injections, followed by tumbling, cooking, and chilling. Raw samples were analyzed for pH, oxidation-reduction potential, and pigment evaluation. Results indicated a significant role of induced in situ conditions of raw meat in the occurrence of pinking. Presence of 1 ppm or more of sodium nitrite in raw meat produced significant pinking of cooked meat. The light muscle color group was least affected and the dark group was most affected by induced pH, oxidation-reduction potential conditions, and metmyoglobin and nitrosopigment content. The predictive ability of the logistic model was more than 90% with nitrosopigment, pH, and reducing conditions being the most important factors. Moreover, validation of the model was confirmed by close association between observed pink samples and those predicted as pink.

Evaluation of induced color changes in chicken breast meat during simulation of pink color defect.

The objective of the study was to establish a pink threshold and simulate the pink defect in cooked chicken breast meat with treatment combinations that would induce significant changes in the color of raw and cooked meat. The subjective pink threshold used in judging pink discoloration was established at a* = 3.8. Samples of three color groups (normal, lighter than normal, and darker than normal) of boneless, skinless chicken breast muscles were selected based on instrumental color values. The in situ changes were induced using sodium chloride, sodium tripolyphosphate, sodium erythorbate, and sodium nitrite at two levels: present and not present. Fillets in all treatments were subjected to individual injections, followed by tumbling, cooking, and chilling. Samples were analyzed for color [lightness (L*), red/green axis (a*), yellow/blue axis (b*)] and reflectance spectra. Simulation of the pink defect was achieved in eight of the 16 treatment combinations when sodium nitrite was present and in an additional two treatment combinations when it was absent. Pinking in cooked samples was affected (P < 0.05) by L* of raw meat color. Results confirmed that it was possible to simulate the undesired pinking in cooked chicken white meat when in situ conditions were induced by sodium chloride, sodium tripolyphosphate, and sodium nitrite. The continuation of the simulation study can aid in developing alternative processing methods to eliminate potential pink defects.

Consumer acceptance of fresh-cut iceberg lettuce treated with 2% hydrogen peroxide and mild heat.

An antibacterial treatment consisting of 2% hydrogen peroxide at 50 degrees C for 60 s was evaluated for its effects on the sensory quality of fresh-cut iceberg lettuce. Treated lettuce was packaged in polyethylene film by a protocol used in the fresh-cut produce industry and then stored along with untreated controls for 3, 10, and 15 days at 5 degrees C. Gas chromatographic analysis confirmed that the desired initial volume (approximately 6 liters) and oxygen gas content (approximately 10%) were maintained during storage. Consumers from the local community who were the primary shoppers for their households and who purchased and ate lettuce regularly evaluated the appearance, color, aroma, flavor, and texture of the lettuce and their overall liking of the lettuce. Forty consumers were recruited to evaluate processing replication 1 on 26 April, and another 40 were chosen to evaluate processing replication 2 on 3 May. Because replication differences were observed in instrumental color measurements and in mean sensory ratings, replications were not pooled for the two test dates. Lettuce purchased for processing replication 2 was considerably greener than that used in replication 1. Overall, the antibacterial treatment was more effective than the control treatment in maintaining sensory quality over 15 days of storage, provided that the lettuce was initially intensely green. Three-fourths of the participants indicated that they would be willing to buy precut packaged lettuce that had already been treated at the packinghouse or processing plant with an antibacterial solution, and of these participants, 62.5% indicated that they would be willing to pay 5 to 10 cents more per bag.

Effects of homogenization pressure and stabilizers on some physical characteristics of a beverage prepared from partially defatted, roasted peanuts.

A low-fat beverage with roasted peanut flavor was developed from peanuts. The potential milk substitute contained 11.8% total solids, 2.0% fat and 3.7% protein, and was whitish orange-yellow in color. The effects of stabilizing additives and homogenization pressure (13.8 x 10(6) Pa or 41.4 x 10(6) Pa) on selected physical characteristics were determined. Suspension stability was improved by addition of carrageenan [Benlacta CM61-B (CM), 0.02-0.04%] or a hydrogenated mono- and diglyceride [Emuldan HV52K (HV, 0.2-0.4%)]. Homogenizing at 41.4 x 10(6) Pa increased viscosity of all samples except that of the controls but did not improve the suspension stability (top:bottom solids) of the beverage. The most viscous formulations (17.5 +/- 0.95 cps) were those containing 0.04% CM. Treatments yielding the best combination, compared to cow's milk values, of high suspension stability (0.5 +/- 0.03, where 1.0 = maximum stability) and low viscosity (3.7 +/- 0.89 cps) were those containing 0.2% HV which were homogenized at 13.8 x 10(6) Pa.

Inactivation of Salmonella montevideo on Tomatoes by Applying Cellulose-Based Edible Films.

The effect of applying edible coatings to mature-green tomatoes on the survival of Salmonella montevideo on the surface and in core tissue was investigated. A hydroxypropyl methylcellulose (HPMC) coating significantly (P ≤ 0.05) reduced the number of viable S. montevideo cells on the surface of tomatoes. However, only about a 2-log-unit reduction was achieved in core tissue. The addition of citric acid, acetic acid, or sorbic acid (0.2 to 0.4%) to HPMC did not substantially enhance bactericidal activity. Concentrations of 72 to 88% ethanol in HPMC were most effective in inactivating S. montevideo on the surface of tomatoes. Inactivation of S. montevideo in core tissue was similar when tomatoes were dipped in 55 to 88% ethanol solutions. Application of HPMC coating retarded the rate of loss of firmness and change in color of tomatoes stored at 20°C for up to 18 days.