GROWTH DYNAMICS OF INDIGENOUS MICROBIAL POPULATIONS ON VEGETABLES AFTER DECONTAMINATION AND DURING REFRIGERATED STORAGE

To ensure microbiological stability and safety in minimally processed (MP) salad vegetables, it is essential to consider the microbiology of this produce during cultivation and harvesting, and the potential changes to this microbiology through preparation, distribution and storage. This study takes two salad vegetables (lettuce and white cabbage) and, having enumerated a range of different physiological groups of microorganisms present on unwashed produce, determines the impact on each microbial group of applying a decontamination step in the preparation protocol. The disinfectant used was sodium dichloroisocyanurate. Decontamination reduced the total microbial load significantly on both vegetables. The levels of different microbial groups enumerated differed significantly between vegetables. All the microbial populations were reduced, but the biocidal effect of chlorine treatment varied with vegetable type. Reduction of the levels of lactic acid bacteria and aerobic psychrotrophs on cabbage was only achieved with inclusion of the decontamination step, and this effect, in general, did not last more than 3 days. Decontamination significantly reduced the levels of coliforms, and although the levels increased during refrigerated storage, they did not exceed initial levels found on unwashed produce. In addition, the levels found on treated cabbage remained lower than produce washed with water only.     

Aroma, Color, and Lipid Oxidation of Turkey Muscle Emulsions

Turkey emulsions were prepared with (1) no additives, (2) sodium chloride (NaCl), (3) sodium nitrite (NaNO₂), (4) sodium ascorbate (NaAsc), or (5) both NaNO₂ and NaAsc. Raw and cooked emulsions from each of the five treatments were stored (?18°C) and then evaluated before and after heating. Emulsions with NaNO₂ and NaAsc contained less malonaldehyde than those with NaCl or no additive and raw turkey emulsions generally contained less malonaldehyde than cooked. Nitrite was the additive that produced the major effect on color of heated emulsions. Generally, emulsions containing both NaNO₂ and NaAsc had the most meaty aroma and the least stale aroma. Emulsions with NaCl tended to have greater stale aroma.     

A RESEARCH NOTE: EFFECT OF CITRIC ACID AND/OR ROSEMARY EXTRACT ON COLOR OF AN IRRADIATED BEEF MYOGLOBIN MODEL SYSTEM

To determine the effect of antioxidants and irradiation on meat color, myoglobin (Mb) was extracted from beef hearts. Mb was treated with one of four antioxidants (control, citric acid [CA], rosemary extract [RE] or combination of citric acid and rosemary extract [CA/RE]) and irradiated at 0.00 (Control), 0.50, 0.75, 1.00, 1.25, 1.50, 1.75 and 2.00 kGy. Samples were then evaluated for thiobarbituric reactive substances, pH, L*, a* and b* values, hue angles, and Chroma. RE- and CA-containing samples had the highest postirradiation L*, a* and b* values, indicating they were lighter, redder and more yellow than controls. In terms of hue angles, all samples treated with antioxidants were much closer to the true red axis ( a* =  0) of the CIE color space, both before and after irradiation, than was the control . The only color attribute affected by irradiation dose was L* value. Samples irradiated at 2.0 kGy were significantly lighter ( L* =  5.27) than samples that had not been irradiated ( L* =  1.28).

PRACTICAL APPLICATIONS

Irradiation is an effect method for extending the shelf life and improving the safety of fresh meat products; however, it can cause undesirable color changes at the surface of the meat, which appear to be the result of oxidative processes – therefore, reducing oxidation could effectively reduce color change. Studying pigment preservation is difficult in intact muscle tissue, so a myoglobin model system was developed for this purpose. Natural antioxidants were evaluated in this system. Rosemary extract and citric acid maintained color lightness and redness. Surface application of these antioxidants has the potential to preserve red meat color during irradiation.     

Protein Extractability of Turkey Breast and Thigh Muscle with Varying Sodium Chloride Solutions as Affected by Calcium, Magnesium and Zinc Chloride

Ground turkey breast and thigh muscle were extracted with various NaCl solutions with or without added CaCl₂, MgCl₂, or ZnCl₂ (0.05%). Protein solubility was increased by CaCl₂ and decreased by ZnCl₂ in each muscle type. At 4% NaCl, MgCl₂ increased thigh myosin solubility by 30%, compared to the control, whereas CaCl₂ had no effect. At 2% and 4% NaCl, breast myosin was not affected by MgCl₂ or CaCl₂. Myosin was not detected for either muscle type when ZnCl₂ was used. All three salts increased breast actin solubility but only MgCl₂ increased thigh actin solubility. The CaCl₂ resulted in the highest overall protein solubility and MgCl₂ resulted in the highest thigh myosin and actin solubility at 4% NaCl.     

SENSORY, COLOR, AND COMPOSITION CHARACTERISTICS OF YOUNG AND MATURE CHEVALINE

Data concerning the sensory attributes of chevaline, although limited, are of interest particularly to markets where it is sold as a human food. Thus, this study was conducted to characterize the sensory attributes of steaks from chevaline longissimus muscle from both younger (2–4 years of age: N = 10) and older animals (4 years and older: N = 10). Uncooked steaks (2.5 cm thick) were evaluated for moisture, fat, and protein content as well as color, instrumentally (L*, a*, and b*) and visually (lightness, redness, and brownness). Steaks were cooked to 70C (internal temperature) and then served to a sensory panel and evaluated by Warner-Bratzler shear. No differences (P < 0.05) were observed between age groups for sensory or color characteristics. Steaks from young animals had lower (P < 0.05) shear force values and protein content. Results suggest that age has limited effects on the composition, sensory, and color characteristics of chevaline steaks.     

TBA Values, Sensory Characteristics, and Volatiles in Ground Pork During Long-term Frozen Storage: Effects of Packaging

Ground pork (30% fat) was packaged in vacuum bags (V), polyvinyl chloride film (P), Saran Wrap?(S), aluminum foil (A), or Saran?-aluminum foil combination (SA) and frozen at - 17°C for 13, 26, and 39 wk. Samples were analyzed for TBA value and pH. Volatiles were steam distilled, volatilized at 60°C, and 1 mL samples of headspace gas was analyzed using gas chromatography and mass spectrometry. Spectra for individual peaks on the total ion chromatograms were identified with spectra from known standards. Ground pork (cooked to 75°C) was evaluated by a trained sensory panel for flavor and texture. Rancid and acid odor and flavor scores and TBA values increased over time regardless of packaging treatment; however, V-packaged pork had lower scores and P-packaged had higher scores at all time periods than did that in other materials. Eighteen volatiles were identified and quantified using GC/MS; 3-hydroxy-2-butanone had the highest correlation coefficients with TBA value, odor, and flavor scores.     

Damage to Pork Liver Caused by Repeated Freeze-Thaw Cycling and Refrigerated Storage

The effects of freezing and thawing (F-T) and refrigerated storage (R-S) on pork liver were examined. Intact cells were isolated from the tissue and analyzed for membrane integrity and the tissue extracts were analyzed for protein content. Significant (p < 0.05) differences were noted in the number of isolated intact cells and in tissue protein content between F-T and R-S or fresh livers. Differences in cell membrane integrity were also noted between fresh and R-S livers. Repeated freezing and thawing appears to break down the liver structure differently than does refrigerated storage.     

LEADERSHIP IN NEGOTIATIONS AND THE COMPLEXITY OF CONCEPTUAL STRUCTURE.

DYAD NEGOTIATION TEAMS (HOMOGENEOUS IN COMPLEXITY OF CONCEPTUAL STRUCTURE) OF 40 MALE STUDENTS SPENT SEVERAL HOURS ATTEMPTING TO SOLVE A SIMULATED INTERNATIONAL CONFLICT SITUATION. EVERY S REPEATEDLY RATED HIMSELF AND THE OTHER PARTICIPANTS ON STOGDILL'S 10 LEADERSHIP CHARACTERISTICS. THE DYAD MEMBER WITH THE OVERALL HIGHEST RATINGS ON ALL SCALES WAS THE LEADER. THE EFFECT OF SIMPLICITY AND COMPLEXITY OF CONCEPTUAL STRUCTURE ON THE DEGREE TO WHICH LEADERS DISPLAY STOGDILL'S LEADERSHIP CHARACTERISTICS WAS ANALYZED. THE INTERACTION EFFECT FOR COMPLEXITY AND LEADERSHIP CHARACTERISTICS WAS HIGHLY SIGNIFICANT. COMPLEX LEADERS WERE RATED HIGHER ON TOLERANCE FOR UNCERTAINTY, ASSUMPTION OF LEADERSHIP ROLE, CONSIDERATION, AND PREDICTIVE ACCURACY. SIMPLE LEADERS WERE RATED HIGHER ON INITIATION OF STRUCTURE, PRODUCTION EMPHASIS, AND DEMANDS RECONCILIATION. (22 REF.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)