Effects of antioxidants and gamma irradiation on the shelf life of beef patties

Effect of Swiss Chard (Beta vulgaris var. cicla) as Nitrite Replacement on Color Stability and Shelf-Life of Cooked Pork Patties during Refrigerated Storage

In this study, the effects of pre-converted nitrite from Swiss chard powder (PS) on the color stability and shelf-life of cooked pork patties during refrigerated storage for 28 d were investigated. Nitrite was added at a concentration of approximately 120 ppm. Five treatments were formulated as follows: Control (120 ppm nitrite), T1 (2% PS), T2 (2% pre-converted nitrite from celery powder; PC), T3 (1% PS + 60 ppm nitrite), and NC (nitrite-free). The T1 and T3 samples had higher nitrosoheme pigment contents, which were associated with the redness of the samples (p<0.05). T1 resulted in the highest redness value (p<0.05). The redness and yellowness of the cooked pork patties increased with increasing PS levels. The pH of the samples subjected to all treatments decreased with progress of the storage period (p<0.05). The pH of the T1 and T3 samples treated with PS was lower (p<0.05) than that obtained with other treatments, as PS has a lower pH value. The treatments in which PS was added were most effective for reducing the level of thiobarbituric acid reactive substances (TBARS) and the residual nitrite content relative to the control. T1 resulted in the highest flavor, off-flavor, and overall acceptability scores during storage (p<0.05). The total viable bacterial count for all treatments was below 1 Log CFU/g, and E. coli and coliform bacteria were not detected during storage. Therefore, these results suggested that pre-converted nitrite from Swiss chard powder is a potential replacement for nitrite in meat products.

Sensory characteristics and cross-cultural consumer acceptability of Bulgogi (Korean traditional barbecued beef)

Bulgogi (Korean traditional barbecued beef) is the most well-known Korean food to foreigners. There are, however, few studies on its sensory characteristics and consumer acceptability. This study was performed to identify the sensory attributes of Bulgogi samples prepared with different formulation and to compare the consumer acceptability in Korea and the United States. Bulgogi samples were prepared with varying levels of sugar and soy sauce with/without garlic or sesame oil. Descriptive analysis was conducted by 8 trained panelists. In consumer tests, 42 consumers in Seoul, Korea, 53 consumers in Davis (Calif., U.S.A.), and 39 consumers in St. Paul (Minn., U.S.A.) participated. Higher levels of sugar and soy sauce (SSS) significantly increased sweetness, saltiness, MSG taste, and soy sauce odor/flavor compared to the control made with the standard formula (CON). Elimination of sesame oil (ESO) significantly decreased sesame oil odor/flavor and oiliness, but increased green onion flavor. Elimination of garlic (EGC) significantly increased grilled beef odor/flavor, sesame oil odor/flavor, and oiliness, but decreased intensities of all the other attributes except bitterness. The consumers in Korea and the United States rated their overall liking for all samples similarly, preferring SSS to CON, EGC, and ESO. However Korean consumers seemed to detect the differences caused by formulation changes better than the U.S. consumers and these perceived differences seemed to impact the hedonic and the just-about-right ratings. Increase in soy sauce and sugar increased both Korean and the U.S. consumers' acceptability of Bulgogi, whereas eliminating garlic did not influence the consumer acceptability despite of its significant impact on sensory attributes.

PRACTICAL APPLICATION

The food industry is increasingly interested in ethnic foods that satisfy sophisticated appetite of today's consumers. Korean cuisine is recently gaining popularity and perceived as "adventurous and spicy," appealing to researchers and marketers in the food industry worldwide. However, it is not easy to develop a new product based on ethnic cuisine because nonsensory factors, such as food neophobia and openness to new culture, can evoke adverse responses from the consumers. A systematic sensory approach can guide the product development by identifying both sensory and nonsensory factors affecting consumer acceptability. This study investigated sensory attributes of Bulgogi (Korean traditional barbecued beef), one of the most famous Korean foods, and compared consumer acceptability between Korea and the United States. The outcomes of this study, such as flavor profiles, consumer responses, evaluation procedure, and approaches taken for cross-cultural comparison, will provide the food industries with valuable information that will help to develop effective strategies for commercializing ethnic foods including recipe development for Bulgogi marinades.

The use of natural herbal extracts for improving the lipid stability and sensory characteristics of irradiated ground beef

Ground Longissimus dorsi of beef were treated with herbal extracts of marjoram, rosemary and sage at concentration of 0.04% (v/w), radiation (2 or 4.5 kGy) or their combination. Treated samples were stored at 5°C and analyzed periodically for thiobarbituric acid reactive substances (TBARS), sensory characteristics and psychrotrophic bacterial counts during storage for 41 and 48 days for samples treated at 2 and 4.5 kGy respectively. Results demonstrated a significant benefit of the addition of herbal extracts to the ground beef prior to irradiation. All three extracts significantly (P<0.05) lowered the TBARS values and off-odor scores and significantly (P<0.05) increased color and acceptability scores in all samples with marjoram being the most effective. The combination treatment with herbal extracts plus irradiation resulted in extension of the shelf life of samples treated with 2 kGy by one week and samples treated with 4.5 kGy by two weeks, over that treated with irradiation alone. In conclusion, the addition of herbal extracts can minimize lipid oxidation, improve color and decrease off-odor production in irradiated ground beef.

Improving ground beef safety and stabilizing color during irradiation using antioxidants, reductants or TSP

The objective of this research was to extend ground beef retail display life using antioxidants, reductants, and/or TSP treatments combined with electron beam irradiation. Ground beef was produced with added butylated hydroxyanisole (BHA) plus butylated hydroxytoluene (BHT) with the following combinations; (1) ascorbate; (2) trisodium phosphate(buffer); (3) erythorbate; (1) and (2); (1) and (3); (1), (2), and (3); and an untreated control, C. Half of the treated samples were irradiated (I) at 2.0kGy-absorbed dose under a nitrogen atmosphere, half remained non-irradiated (N). Samples were displayed under atmospheric oxygen and evaluated for total aerobic plate count (TPC), thiobarbituric acid reactive substances (TBARS) and instrumental color during 9d of simulated retail display (SRD). Controls had the highest (P<0.05) TBARS value and the lowest (P<0.05) redness (CIE a∗), proportion of oxymyoglobin and vividness. Treated irradiated samples were just as red and vivid on SRD day 9 as the non-irradiated untreated control at day 0. Treatments stabilized color and lipids of ground beef after irradiation and during SRD.

Combined effect of carvacrol and packaging conditions on radiosensitivity of Escherichia coli and Salmonella Typhi in ground beef

This study was undertaken to evaluate the effect of 1.0% carvacrol and 0.1% tetrasodium pyrophosphate on the radiation D10 of Escherichia coli and Salmonella Typhi added to ground beef at a concentration of 10(5) CFU/g. The ground beef was then packaged under four different atmosphere conditions: air (78.1% N2, 20.9% O2, 0.036% CO2), 100% CO2, modified atmosphere (60% O2, 30% CO2, 10% N2) and vacuum. Samples were irradiated at doses of 0.1 to 0.6 kGy for E. coli and 0.5 to 2.0 kGy for Salmonella Typhi. Radiation D10-values of 0.126 and 0.526 kGy were observed for E. coli and Salmonella Typhi, respectively, when meat was packed under air. When meat was packed under modified atmosphere conditions, the radiation D10-values for E. coli and Salmonella Typhi were 0.086 and 0.221 kGy, respectively. The addition of carvacrol and tetrasodium pyrophosphate and the use of modified atmosphere packaging reduced the radiation D10-value from 0.126 to 0.046 kGy for E. coli and from 0.526 to 0.053 kGy for Salmonella Typhi. Under vacuum and 100% CO2 conditions, the radiation D10 reduction was not as great as that for the modified atmosphere regardless of the presence or absence of carvacrol and tetrasodium pyrophosphate.

Radiosensitization of Escherichia coli and Salmonella Typhi in ground beef

The radiosensitization of two pathogenic bacteria, Escherichia coli and Salmonella Typhi, was evaluated in the presence of thyme and its principal essential oil constituents (carvacrol and thymol) in ground beef. Ground beef was inoculated with E. coli or Salmonella Typhi (10(5) CFU/g), and each compound was added separately at various concentrations (0 to 3.5%, wt/wt). The antimicrobial potential of carvacrol, thymol, and thyme was evaluated in unirradiated meat by determining the MIC in percentage (wt/wt) after 24 h of storage at 4 +/- 1 degree C. Results showed a MIC of 0.88 +/- 0.12%, 1.14 +/- 0.05%, and 2.33 +/- 0.32% for E. coli in the presence of carvacrol, thymol, and thyme, respectively. MICs of 1.15 +/- 0.02%, 1.60 +/- 0.01%, and 2.75 +/- 0.17% were observed for Salmonella Typhi in the presence of the same compounds, respectively. The best antimicrobial compound (i.e., carvacrol) was selected and added to the sterilized ground beef along with ascorbic acid (0.5%, wt/wt) and tetrasodium pyrophosphate (0.1%, wt/wt). Meat samples (10 g) were packed in air and then irradiated in a 60Co irradiator at doses of 0 to 0.7 kGy for the determination of E. coli radiation D10 and 0 to 2.25 kGy for the determination of Salmonella Typhi radiation D10. Addition of carvacrol increased the relative sensitivity of both bacteria 2.2 times. The radiation D10 was reduced from 0.126 +/- 0.0039 to 0.057 +/- 0.0015 kGy for E. coli and from 0.519 +/- 0.0308 to 0.235 +/- 0.0158 kGy for Salmonella Typhi. The addition of tetrasodium pyrophosphate did not affect significantly (P > 0.05) the radiosensitization of either bacterium. However, the presence of ascorbic acid in the media reduced significantly (P < or = 0.05) the radiosensitivity of both bacteria. An additive effect of carvacrol addition and packaging under modified atmosphere conditions (60% O2-30% CO2-10% N2) was also observed on bacterial radiosensitization at 4 degrees C. Compared with the control packed under air, modified atmosphere packaging conditions in the presence of carvacrol and tetrasodium pyrophosphate improved the relative sensitivity of E. coli by 2.7 times and Salmonella Typhi by 9.9 times.

Antioxidant power, lipid oxidation, color, and viability of Listeria monocytogenes in beef bologna treated with gamma radiation and containing various levels of glucose

Ionizing radiation can be used to pasteurize ready-to-eat (RTE) meat products. Thermal processing of RTE meats that contain dextrose results in the production of antioxidants that may interfere with ionizing radiation pasteurization of RTE meat products. Beef bologna was manufactured with dextrose concentrations of 0, 2, 4, 6, and 8%. Antioxidant activity, as measured by the Ferric Reducing Antioxidant Power assay, increased with dextrose concentration but was unaffected by ionizing radiation. Lipid oxidation increased significantly in irradiated bologna (4 kGy) that contained dextrose. Hunter color analysis indicated that the addition of dextrose reduced the ionizing radiation-induced loss of redness (a-value) but promoted the loss of brightness (L-value). The radiation resistance, D10-value, of Listeria monocytogenes that was surface-inoculated onto bologna slices was not affected by dextrose concentration. L. monocytogenes strains isolated from RTE meats after listeriosis outbreaks were utilized. Increased antioxidant activity generated by thermal processing of dextrose in fine emulsion sausages does not present a barrier to radiation pasteurization of RTE meats. However, a high dextrose concentration in combination with gamma irradiation increases lipid oxidation significantly.

Combined effect of antimicrobial coating and gamma irradiation on shelf life extension of pre-cooked shrimp (Penaeus spp.)

The present study was conducted to evaluate the combined effect of low-dose gamma irradiation and antimicrobial coating on the shelf life of pre-cooked shrimp (Penaeus spp.). Antimicrobial coatings were obtained by incorporating various concentrations of thyme oil and trans-cinnamaldehyde in coating formulations prepared from soy or whey protein isolates. Coated shrimps were stored at 4 +/- 1 degrees C under aerobic conditions and were periodically evaluated for aerobic plate counts (APCs) and Pseudomonas putida. Sensory evaluations were performed for appearance, odor, and taste using a hedonic test. Results showed that gamma irradiation and coating treatments had synergistic effects (p < or = 0.05) in reducing the APCs and P. putida with at least a 12-day extension of shelf life. Without irradiation, the inhibitory effects of the coating solutions were closely related to the concentration of thyme oil and trans-cinnamaldehyde. No detrimental effects of gamma irradiation on organoleptic parameters (appearance, odor, and taste) were observed. However, incorporation of thyme oil and trans-cinnamaldehyde reduced the acceptability scores for taste and odor.