Effects of Carbon Monoxide Packaging on Color and Lipid Stability of Irradiated Ground Beef

ABSTRACT: The effects of packaging atmosphere (aerobic, vacuum, or modified atmosphere with carbon monoxide) on ground beef treated with ionizing radiation were investigated. Measurements of color (CIE L*, a*, b*), lipid oxidation (TBA value), and sensory quality were conducted during 28 d of storage at refrigerated (0 to 2°C) temperatures. Irradiation significantly ( p > 0.001) decreased color scores and increased TBA and off-odor scores. The MAP + CO treatments increased the L* and a* values ( p < 0.001), regardless of irradiation dose. The TBA values for MAP + CO-packaged samples were well below the levels considered "rancid" (about 1.0). In addition, sensory scores indicated minimal production of irradiation off-odors with MAP + CO packaging.     

CARBON MONOXIDE EFFECTS ON COLOR AND MICROBIAL COUNTS OF VACUUM-PACKAGED FRESH BEEF STEAKS IN REFRIGERATED STORAGE

Ribeye, top round, and eye of round steaks were treated for 30 min with 100% carbon monoxide (CO), vacuum packaged, and held in refrigerated storage. Instrumental color determinations (L*, a*, and b* values) were made on uncooked ribeye and round steaks every 7 days. Aerobic plate counts (APC), psychrotrophs, and lactic acid bacteria (LAB) were determined on eye of round samples after 1, 4, and 8 weeks. Initially, CO-treated steaks were more red (higher a* values) than untreated steaks. The a* values of treated steaks decreased during storage; at 6 weeks no differences existed due to CO treatment. CO-treated steaks were more yellow (higher b* values) at all storage times than untreated steaks. APC of CO-treated samples were 1 log cycle lower than control after 8 weeks in storage; LAB counts were nearly 1 log cycle lower for CO-treated samples after 8 weeks. Psychrotrophic counts were similar for control and CO-treated samples during the first 4 weeks of refrigerated storage but were nearly 2 log cycles lower for CO-treated samples after 8 weeks. These data suggest that CO-treated steaks are more red and that they have extended shelf-lives compared with untreated, vacuum-packaged steaks.     

EFFECT OF HEATING ON RESIDUAL CARBON MONOXIDE CONTENT IN CO-TREATED TUNA AND MYOGLOBIN

Carbon monoxide (CO) can be used by food manufacturers to retain the red color of meat or dark fish prior to vacuum packaging or in the modified atmosphere packaging. Yellowfin tuna steak (c. 1.5 cm) was treated with CO gas, then packaged in a vacuum bag and heated at a constant temperature ranging from 50 to 100C for 30 min. A myoglobin (Mb) solution was prepared from tuna dark muscle and purged with CO gas for comparison. The released CO concentration and the residual CO in the tuna flesh or Mb solution were measured by gas chromatography. The higher level of CO concentration in the vacuum bag from CO‐treated tuna was found for conditions with temperatures above 80C. The content of residual CO in the CO‐treated tuna steaks after heating was much higher than that in untreated flesh. Regardless of the temperature of heating, a ratio of 58–82% CO was released from Mb solution after heating. This suggested that MbCO was not completely dissociated by heating at temperatures ranging from 50 to 100C.     

Effect of pH and prefreezing treatment on the texture of yellowtail rockfish (Sebastes flavidus) as measured by the Ottawa Texture Measuring System

Texture is very important to the organoleptic quality of fish products. Poor frozen storage conditions or improper prefreezing treatment can result in unacceptably tough fillets. With some species, undesirable soft, mushy texture develops during chill storage.
This study is concerned with the influence of treatment prior to freezing (samples were frozen pre-rigor, in-rigor, post-rigor and after 6 days' chill storage in ice or refrigerated sea water) on the texture of yellowtail rockfish stored frozen as whole gutted fish or as fillets. The effect of pH was also studied. Texture was measured objectively using the Ottawa Texture Measuring System on samples stored for 6 months at −28°C.
A very good negative correlation was found between pH level and toughness as measured using a Kramer shear-compression cell in the Ottawa Texture Measuring System. Fish stored in refrigerated sea water prior to freezing were appreciably more tender. There was no statistical difference in texture (shear press force) values between samples stored as whole fish versus samples stored as fillets.     

Optimization of the Freezing Conditions on Mackerel and Amberfish for Manufacturing Minced Fish

Optimal freezing, frozen storage and thawing conditions in preserving mackerel and amberfish for producing minced fish products were investigated. Based on assessments of extractability of 0.6M KCl-soluble proteins and actomyosin, Ca-ATPase activity of actomyosin, and gel-forming ability of kamaboko (kind of minced fish meat product), semi-dressed, dressed, and filleted samples showed stable and good quality of gel-forming ability during 3 months storage at −20°C. Optimal ultimate freezing temperatures of mackerel and amberfish were −20°C and between −30°C and −40°C, respectively. The optimal storage temperatures for mackerel and amberfish were −20°C and −40°C, respectively. Appropriate thawing methods for frozen mackerel were microwave and 20°C running water defrosting, while those for frozen amberfish were microwave, 20°C running water, and room temperature defrosting.     

Combined effect of aqueous chlorine dioxide and modified atmosphere packaging on inhibiting Salmonella Typhimurium and Listeria monocytogenes in mungbean sprouts

This study was conducted to investigate the effect of chlorine dioxide (ClO2) combined with modified atmosphere packaging (MAP) on inhibiting total mesophilic microorganisms, Salmonella Typhimurium, and Listeria monocytogenes in mungbean sprouts during refrigerated storage. Mungbean sprouts were packaged using 4 different methods (air, vacuum, CO2 gas, and N2 gas) following treatment with water or 100 ppm ClO2 for 5 min and stored at 5 +/- 2 degrees C. The population of total mesophilic microorganisms in mungbean sprouts was about 8.4-log(10) CFU/g and this level was not significantly reduced by treatment with water or ClO2 (P > 0.05). However, when samples were packaged under vacuum, N2 gas, or CO2 gas following treatment with ClO2, the populations of total mesophilic microorganisms were significantly reduced during storage (P < 0.05). Levels of S. Typhimurium and L. monocytogenes in mungbean sprouts following inoculation were 4.6- and 5.6-log(10) CFU/g and treatment with water followed by different packaging conditions (air, vacuum, N2 gas, and CO2 gas) had no significant effect on population reduction (P > 0.05). However, treatment with ClO2 significantly reduced populations of S. Typhimurium and L. monocytogenes by 3.0- and 1.5-log CFU/g, respectively (P < 0.05), and these reduced cell levels were maintained or decreased in samples packaged under vacuum or in N2 or CO2 gas during storage. These results suggest that the combination of ClO2 treatment and MAP such as CO2 gas packaging may be useful for inhibiting microbial contamination and maintaining quality in mungbean sprouts during storage.     

SHELF-LIFE DETERMINATION OF PRECOOKED FROZEN PORK MEAT PATTIES AT VARIOUS TEMPERATURES

Precooked frozen pork patties sampled from the same lot were stored at −10, −15 and −20C after vacuum packing in PE bags for the determination of shelf -life. The patties were sampled 10–13 times at 3–4 week intervals and were subjected to the determination of volatile basic nitrogen (VBN), peroxide value (POV), thiobarbituric acid reactive substances (TBA), surface color and texture after thawing at 5C for 15 h. Results from the triangle test were used to determine high quality life (HQL), and the scoring test and the quality index were used to determine practical quality life (PQL). The test results showed that VBN, TBA and POV in the samples increased as the storage period was extended. It was noted that color of samples became darker during the storage as indicated by the decrease in L value from 63.7 to 59.2. In addition, the shear force of the stored samples increased from 3.2 to 5.5 psi during the storage period. HQL of the meat patties were 147, 168 and 196 days, and the PQL 189, 224 and 252 days at −10, −15 and −20C, respectively. Statistical analysis of test results indicated that there were significant relationships between sensory scores and VBN, TBARS and POV of the stored patties (P<0.05). VBN was selected as the most reliable objective quality index for the shelf-life determination (PQL) of the precooked frozen meat patties, and PQL estimates based on VBN were close to those determined based on the sensory tests.     

Pathogen Reduction and Quality of Lettuce Treated with Electrolyzed Oxidizing and Acidified Chlorinated Water

ABSTRACT: The efficacy of electrolyzed oxidizing (EO) and acidified chlorinated water (45 ppm residual chlorine) was evaluated in killing Escherichia coli O157:H7 and Listeria monocytogenes on lettuce. After surface inoculation, each leaf was immersed in 1.5 L of EO or acidified chlorinated water for 1 or 3 min at 22 °C. Compared to a water wash only, the EO water washes significantly decreased mean populations of E. coli O157:H7 and L. monocytogenes by 2.41 and 2.65 log10 CFU per lettuce leaf for 3 min treatments, respectively (p < 0.05). However, the difference between the bactericidal activity of EO and acidified chlorinated waters was not significant (p > 0.05). Change in the quality of lettuce subjected to the different wash treatments was not significant at the end of 2 wk of storage.     

New Technology for Producing Paste-like Fish Products using Lactic Acid Bacteria Fermentation

ABSTRACT: To develop a new processing technique, mackerel mince was homogenized to obtain different media with protein concentration of 90, 45, 22.5 mg/mL, respectively. Lactic acid bacteria (LAB) were inoculated to the media. During 48 h fermentation at 37 °C, rapid growth of LAB, decline in pH, suppression of main microflora, and increases in whiteness, Hunter L and sensory quality were observed and the VBN of fermented samples was still below 25 mg/100g. After 24 and 48 h fermentation, the sensory evaluation and photographic records indicated the high acceptability of the fermented products. From this study, various LAB fermented fish products can be produced and this technique has very high commercial potential.     

Evaluation of rib steak colour from Friesian, Hereford and Charolais heifers pastured or overwintered prior to slaughter

Heifers (n=10) were randomly selected from the slaughter line of a local factory each month for a period of 21 months. Rib steak (sampled at the 10th rib) from the left side of each carcass was taken for analysis. The cattle breeds selected during this study were Friesian, Hereford and Charolais. The mean weight of the left side for all carcasses was 146.6 (S.E.M.= 1.0kg). Graded carcasses selected for sampling during this trial were classified using the EUROP scale and the specific heifer grades chosen were factory grades EO4L and EO4H. Initial Hunter 'a' values (on the day of arrival in the laboratory) of rib steak from heifers finished between November and March (overwintered) were significantly (P<0.001) higher than Hunter 'a' values from heifers finished between April and October (pastured). After storage at 4?°C under simulated retail display conditions for 6 days, the Hunter 'a' values for overwintered samples were also significantly (P<0.001) greater than those for pastured samples. Breed also had an effect on the colour of the meat. After storage for 6 days, Hunter 'a' values of rib steak from Charolais were significantly (P<0.05) higher than either Friesian or Hereford. Pastured heifers had significantly (P<0.05) higher levels of the monounsaturated fatty acid C16.1 in the total lipid fraction of rib steak (neutral and polar) than samples taken from overwintered heifers. Pastured heifers had significantly (P<0.01) higher levels of the polyunsaturated fatty acid (PUFA) C18.3 in the phospholipid fraction than those from overwintered cattle. However, Hereford had significantly (P<0.05) higher levels of C14.0, C16.1 and C18.0 in the phospholipid fraction than those found in Friesian and Charolais. The level of α-tocopherol in the muscle was not affected by either pasturing/overwintering or breed. However, Continental breeds had significantly (P<0.05) higher levels of α-tocopherol in adipose tissue than Friesian.     

Effect of Harvest Treatment on Biochemical Properties of Farmed Chinook Salmon (Oncorhynchus tshawytscha) Tissue during Frozen and Thawed Storage

ABSTRACT:  Two different harvest procedures were employed to investigate whether the method of harvest has an effect upon deteriorative processes that occur during the frozen storage of Chinook salmon ( Oncorhynchus tshawytscha ) white muscle tissue. These 2 harvest methods, termed "rested"—involving sedation with the aquatic anesthetic AQUI-S™ and "exercised"—a simulated conventional harvest not involving sedation, contrasted levels of activity of the animal prior to and upon slaughter. Rested and exercised harvesting protocols produced tissue in significantly different postmortem physiological states prior to freezing. Rested, postharvest tissue maintained high metabolic energy stores of ATP and glycogen within the tissue, with low concentrations of tissue and plasma lactate. Exercised tissue exhibited near depleted concentrations of ATP and glycogen and a marked lactate accumulation. In both treatments, no significant change in metabolite levels was seen over a 6-mo storage period at −19 °C when tissue was frozen immediately postharvest. Transfer of tissue from frozen temperatures (−80 and −19 °C), to refrigerated (−1 and +4 °C, respectively) resulted in rapid glycolysis, depleting tissue ATP and glycogen stores and increasing tissue lactate concentrations. Metabolic activity was more significant in rested tissue owing to the larger concentrations of metabolic energy stores and occurred at temperatures between −3 and −1.5 °C. During frozen storage (−19 °C), there was an increase in the secondary lipid oxidation product TBARS, but harvest treatment had no effect. However, following transfer from frozen to refrigerated (+4 and −1 °C) storage, rested tissue showed a significant ability to retard the development of TBARS products.     

Efficacy of electrolyzed water in the inactivation of planktonic and biofilm Listeria monocytogenes in the presence of organic matter

The ability of electrolyzed (EO) water to inactivate Listeria monocytogenes in suspension and biofilms on stainless steel in the presence of organic matter (sterile filtered chicken serum) was investigated. A five-strain mixture of L. monocytogenes was treated with deionized, alkaline EO, and acidic EO water containing chicken serum (0, 5, and 10 ml/liter) for 1 and 5 min. Coupons containing L. monocytogenes biofilms were also overlaid with chicken serum (0, 2.5, 5.0, and 7.5 ml/liter) and then treated with deionized water, alkaline EO water, acidic EO water, alkaline EO water followed by acidic EO water, and a sodium hypochlorite solution for 30 and 60 s. Chicken serum decreased the oxidation-reduction potential and chlorine concentration of acidic EO water but did not significantly affect its pH. In the absence of serum, acidic EO water containing chlorine at a concentration of 44 mg/liter produced a > 6-log reduction in L. monocytogenes in suspension, but its bactericidal activity decreased with increasing serum concentration. Acidic EO water and acidified sodium hypochlorite solution inactivated L. monocytogenes biofilms to similar levels, and their bactericidal effect decreased with increasing serum concentration and increased with increasing time of exposure. The sequential 30-s treatment of alkaline EO water followed by acidic EO water produced 4- to 5-log reductions in L. monocytogenes biofilms, even in the presence of organic matter.     

Development and validation of a quantitative spectrophotometric method to detect the amount of carbon monoxide in treated tuna fish

In recent years carbon monoxide (CO) has been employed by the fishery industry to preserve the fresh appearance of fish products during frozen storage, particularly in vacuum packaged products. CO reacts with oxy-myoglobin to form a stable cherry coloured carboxy-myoglobin complex. We propose a method that allows the quantitative determination of CO in the meat drip of tuna fish by UV–Vis spectroscopy. It consists of: (i) preparations of CO secondary standard solutions titrated against horse heart Mb primary standard solutions; (ii) determination of calibration curves to measure CO concentration in treated and untreated samples. The accuracy of the spectrophotometric method has been evaluated in terms of trueness and precision by using fortified tuna fish samples. The spectroscopic results have been compared with those obtained using a head space gas chromatographic technique (HS-GC–MS). The CO levels measured in tuna fish samples by UV–Vis are substantially lower than those revealed by HS-GC–MS. The origin of this discrepancy is discussed.     

Quality assessment of filtered smoked yellowfin tuna (Thunnus albacares) steaks

Abstract: Filtered smoke (FS) has been used to preserve taste, texture, and/or color in tuna and other fish species. This treatment is particularly important in color preservation during frozen storage. The objective of this study was to compare changes in the quality profiles of FS‐treated and untreated (UT) yellowfin tuna (Thunnus albacares) steaks stored in 3 ways: room temperature (21 to 22 °C), refrigerated (4 to 5 °C), and iced (0 °C). FS and UT steaks were processed from the same lot of fish and analyzed for chemical, microbiological, lipid oxidation, color, and sensory profiles. Similar trends were seen for microbial proliferation and accumulation of apparent ammonia and total volatile base nitrogen (TVB‐N) during the storage temperatures evaluated. Notable exception in quality profile was found in lipid oxidation which was, as expected, lower for treated samples at all storage temperatures for TBARS (P < 0.05) and lower or significantly (P < 0.05) lower for POV values. FS increased the initial redness value significantly (P < 0.05). Unlike UT product, there was no loss of color value concomitant with quality changes for FS‐treated tuna for all storage temperatures evaluated. Practical Application: The overall goal of this project was to evaluate filtered smoked tuna steaks as to the impact on the overall quality profile. As a color‐stabilizing technology, it could mask deteriorating quality.     

Relationship between Muscle pH and Flesh Color of Atlantic Halibut

ABSTRACT:  After 7 d of ice storage, the muscle pH and flesh color (CIE L *, a *, b *) was measured in 118 Atlantic halibut ( Hippoglossus hippoglossus ) slaughtered at different times of the year. All fish originated from the same stock and the fish were farmed under natural and continuous light and slaughtered fed or starved, representing a wide distribution of fish undergoing different stages of growth, maturation, and sizes (1.5 to 5.9 kg). Results show a considerable variation of end pH ranging from 5.7 to 6.8. The color correlated significantly with muscle pH with R  = −0.63, 0.61, and −0.57 for L *, a *, and b *, respectively, while fillet weight and sampling position on the fillet had less influence on color. We conclude that the end pH of the muscle is an important factor for the visual quality of fish, and in particular for Atlantic halibut. Therefore, measures should be taken to avoid high glycogen levels at death, as this will have a large impact on the muscle pH, with negative consequences for flesh color.     

Efficacy of electrolyzed water in inactivating Salmonella enteritidis and Listeria monocytogenes on shell eggs

The efficacy of acidic electrolyzed (EO) water produced at three levels of total available chlorine (16, 41, and 77 mg/ liter) and chlorinated water with 45 and 200 mg/liter of residual chlorine was investigated for inactivating Salmonella Enteritidis and Listeria monocytogenes on shell eggs. An increasing reduction in Listeria population was observed with increasing chlorine concentration from 16 to 77 mg/liter and treatment time from 1 to 5 min, resulting in a maximal reduction of 3.70 log CFU per shell egg compared with a deionized water wash for 5 min. There was no significant difference in antibacterial activities against Salmonella and Listeria at the same treatment time between 45 mg/liter of chlorinated water and 14-A acidic EO water treatment (P > or = 0.05). Chlorinated water (200 mg/liter) wash for 3 and 5 min was the most effective treatment; it reduced mean populations of Listeria and Salmonella on inoculated eggs by 4.89 and 3.83 log CFU/shell egg, respectively. However, reductions (log CFU/shell egg) of Listeria (4.39) and Salmonella (3.66) by 1-min alkaline EO water treatment followed by another 1 min of 14-A acidic EO water (41 mg/liter chlorine) treatment had a similar reduction to the 1-min 200 mg/liter chlorinated water treatment for Listeria (4.01) and Salmonella (3.81). This study demonstrated that a combination of alkaline and acidic EO water wash is equivalent to 200 mg/liter of chlorinated water wash for reducing populations of Salmonella Enteritidis and L. monocytogenes on shell eggs.     

Efficacy of electrolyzed oxidizing (EO) and chemically modified water on different types of foodborne pathogens

This study was undertaken to evaluate the efficacy of electrolyzed oxidizing (EO) and chemically modified water with properties similar to the EO water for inactivation of different types of foodborne pathogens (Escherichia coli O157:H7, Listeria monocytogenes and Bacillus cereus). A five-strain cocktail of each microorganism was exposed to deionized water (control), EO water and chemically modified water. To evaluate the effect of individual properties (pH, oxidation-reduction potential (ORP) and residual chlorine) of treatment solutions on microbial inactivation, iron was added to reduce ORP readings and neutralizing buffer was added to neutralize chlorine. Inactivation of E. coli O157:H7 occurred within 30 s after application of JAW EO water with 10 mg/l residual chlorine and chemically modified solutions containing 13 mg/l residual chlorine. Inactivation of Gram-positive and -negative microorganisms occurred within 10 s after application of ROX EO water with 56 mg/l residual chlorine and chemically modified solutions containing 60 mg/l residual chlorine. B. cereus was more resistant to the treatments than E. coli O157:H7 and L. monocytogenes and only 3 log10 reductions were achieved after 10 s of ROX EO water treatment. B. cereus spores were the most resistant pathogen. However, more than 3 log10 reductions were achieved with 120-s EO water treatment.     

Antimicrobial Efficiency of Essential Oil and Freeze–Thaw Treatments against Escherichia coli O157:H7 and Salmonella enterica Ser. Enteritidis in Strawberry Juice

ABSTRACT:  This study investigated the antimicrobial efficiency of 3 essential oils (EOs), lemongrass, cinnamon leaf, and basil, and freeze–thaw treatment, alone or in combination, against Escherichia coli O157:H7 and Salmonella enterica Ser. Enteritidis inoculated in strawberry juice stored at 7 °C. EO of lemongrass or cinnamon leaf at 0.1 to 2 μL/mL and freezing at −23 °C for 24 or 48 h followed by thawing at 7 °C for 4 h all showed significant antimicrobial activities ( P < 0.05) against E. coli O157:H7 and S. Enteritidis in strawberry juice. The antimicrobial activity increased with increasing EO concentration and storage time, but extending freezing time from 24 to 48 h did not enhance the antimicrobial activity of freeze–thaw treatment ( P > 0.05). EO of lemongrass or cinnamon leaf at 0.1 μL/mL and freeze–thaw treatment alone obtained a 5 log₁₀ reduction in the population of S. Enteritidis, while EOs at 0.1 to 0.3 μL/mL or freeze–thaw alone could not achieve a satisfactory protection against E. coli O157:H7 in strawberry juice. Combined EO and freeze–thaw treatment enhanced the overall antimicrobial effect against E. coli O157:H7, with adding EO before the freeze–thaw treatment showed a faster decontamination rate than when added EO after the freeze–thaw. EOs of lemongrass and cinnamon leaf at 0.1 or 0.3 μL/mL followed by the freeze–thawing resulted in a 5 log₁₀ reduction in E. coli O157:H7 on the 5th and 2nd day of storage, respectively. This study suggested that combined EO and freeze–thaw treatment may be a suitable and inexpensive method to eliminate microorganisms that can be a hazard for the consumers of unpasteurized berry juices.     

Aerobic Counts, Color and Adenine Nucleotide Changes in CO2 Packed Refrigerated Striped Bass Strips

Hybrid striped bass (HSB) strips were dipped in chlorine or distilled water and packaged in 60% CO₂, 6% O₂, and 34% N₂ (MAP) or in AIR. APC reached 10⁸ CFU/g after 4 days for AIR and 10 days for MAP fish. Sensory panelists detected a whiter color flesh in fish treated with chlorine. Hypoxanthine increased while IMP decreased and ADP and ATP did not change throughout. If inosine was excluded in the predictor, a modified K value (K*) could be applicable as a freshness indicator of freshwater HSB but storage environment should be specified. K* values correlated highly with APC for AIR (R²= 0.84) and MAP packs (R²= 0.85).     

Purine Content in Grass Shrimp during Storage as Related to Freshness

In grass shrimp ( Penaeus monodon ), the combined total content of the uricogenic bases adenine (Ade) and hypoxanthine (Hyp) decreased gradually during storage. Whether stored at 5°C or at room temperature (22°C), a negative regression of log Ade and a positive regression of the Kp value (Hyp/Ade) were observed. Volatile basic nitrogen (VBN) increased during storage at 5°C and 22°C. Correlations between the content of log Ade and VBN at 5°C and 22°C were –0.9248 (p<0.01) and –0.8139 (p<0.05, while those between the Kp value and VBN were 0.9557 (p<0.001) and 0.8197 (p<0.05), respectively. At the point where the shrimp would remain acceptable, the upper limits of Kp were 1.42 and 1.29 for storage at 5°C and 22°C, respectively; the corresponding lower limits of Ade were 18.72 and 20.42 μmole/g dry wt.