Vacuum-packaged Storage Research Articles

Quality characteristics of chicken snacks stored under aerobic and vacuum packaging at 30±2oC

Chicken snacks prepared by utilizing spent hen meat and other necessary ingredients were packaged aerobically as well as under vacuum in laminated (polyethylene/aluminium foil) pouches (size 25X20 cm). They were stored at 30+2 0 C and analysed for physico- chemical characteristics at a regular interval of 0, 6, 12, 18, 24 and 30 days. Chicken snacks indicated none significant effect of storage and packaging systems on contents of moisture, fat, protein, ash. However, significant (P<0.05) difference was observed in thiobarbituric acid (TBA) value, shear force value and pH. Overall storage in vacuum packaging revealed better quality with respect to its physico-chemical qualities with the exception of TBA values. On the basis of present study we can say that chicken snacks can very well preserved at ambient (30±2 o C) temperature for a month under aerobically as well as under vacuum packaging.

Lesions in thighs from hunted Brown Hares (Lepus europaeus) and microflora under vacuum-packaging storage

In two surveys, thighs of a total of 137 hunted hares were tested for the presence of intramuscular shots and femur fractures, which were detected in 42.7% and 29.2% of 274 thighs, respectively. Femur fractures were significantly associated with the presence of intramuscular shots. In the second survey (46 hares), 92 thighs were grouped into three categories, “A” (no fractures, no intramuscular shot), “B” (one intramuscular shot), and “C” (multiple shots and hematoma), with 49.0%, 33.6%, and 17.4%, respectively. Category “C” was found unfit for human consumption. During 7-day storage of vacuum-packed “A” and “B” thighs, total aerobic counts increased from initially 3.3 ± 0.3 (mean ± SD) and 4.1 ± 0.6 log cfu/g by ca. 2 log units when stored at 3–4°C, whereas the increase was clearly <1 log unit at 0°C. In comparison to temperature, differences between “A” and “B” category were less pronounced. Similar dynamics were observed for Enterobacteriaceae. In all categories, muscle pH values (mean = 5.83) were similar. It is concluded that storage at temperatures of ca. 4°C, although in compliance with EU legislation, does not afford keeping microbial contaminants in check, and thus will not preserve microbiological quality of vacuum-packed hare meat.

Colour, lipid and protein stability of Rhea americana meat during air- and vacuum-packaged storage: Influence of muscle on oxidative processes

Physicochemical characteristics and oxidative stability during storage were determined in Gastrocnemius pars interna (GN) and Iliofiburalis (IF) muscles of Rhea americana. Glycolytic potential (GP) and pH decline of muscles were measured within the first 24 h post mortem. Colour, lipid and protein stability were determined during storage of meat, i.e. 5 days under air-packaging at 4°C, or 28 days under vacuum-packaging at 4°C. In parallel, anti-oxidant status of muscles was estimated by measuring α-tocopherol content and anti-oxidant enzyme activities (superoxide dismutase and catalase), while pro-oxidant status was evaluated by determining haeminic iron and long chain fatty acids (especially polyunsaturated fatty acids). The ultimate pH was similar in both muscles, but the GP value was significantly higher in IF than in GN muscle. Haeminic iron and alpha-tocopherol content differed between muscles, with 30% more haeminic iron (p<0.05) and 134% more alpha-tocopherol (p<0.001) in IF than GN muscle. The IF muscle presented higher lipid content and lower PUFA/SFA ratio (polyunsaturated fatty acids/saturated fatty acids) than GN muscle. With storage under air-packaging, lipid and protein oxidation of rhea muscles increased up to 275% and 30%, respectively. This increase was more rapidly and marked in IF muscle. The IF also showed high level of metmyoglobin accumulation after 3 days of storage (47%) and was rejected by 1 consumer out of 2 in sensorial analysis. Under vacuum-packaging, both muscles showed a high stability of colour and no oxidation of lipids and proteins.

Microwave Oven Heating for Inactivation of Listeria Monocytogenes on Frankfurters before Consumption

Microwave oven heating was evaluated for inactivation of Listeria monocytogenes on inoculated and stored frankfurters. Frankfurters formulated without/with 1.5% potassium lactate and 0.1% sodium diacetate were inoculated with L. monocytogenes (1.9 +/- 0.2 log CFU/cm(2)), vacuum-packaged, and stored (4 degrees C) to simulate conditions prior to purchase by consumers. At storage days 18, 36, and 54, packages were opened and placed at 7 degrees C, simulating aerobic storage in a household refrigerator. At 0, 3, and 7 d of aerobic storage, 2 frankfurters were placed in a bowl with water (250 mL) and treated in a household microwave oven at high (1100 W) power for 30, 45, 60, or 75 s, or medium (550 W) power for 60 or 75 s. Frankfurters and the heating water were analyzed for total microbial counts and L. monocytogenes populations. Exposure to high power for 75 s reduced pathogen levels (0.7 +/- 0.0 to 1.0 +/- 0.1 log CFU/cm(2)) to below the detection limit (<-0.4 log CFU/cm(2)) on frankfurters with lactate/diacetate, even after 54 d of vacuum-packaged storage followed by 7 d of aerobic storage. For frankfurters without lactate/diacetate, high power for 75 s caused reductions between > 1.5 and 5.9 log CFU/cm(2) from control levels of 1.5 +/- 0.1 to 7.2 +/- 0.5 log CFU/cm(2). Depending on treatment and storage time, the water used to reheat the frankfurters had viable L. monocytogenes counts of <-2.4 to 5.5 +/- 0.5 log CFU/mL. The results indicated that frankfurters should be reheated in a microwave oven at high power for 75 s to inactivate up to 3.7 log CFU/cm(2) of L. monocytogenes contamination.

Survival of Listeria monocytogenes in a Simulated Dynamic Gastrointestinal Model during Storage of Inoculated Bologna and Salami Slices in Vacuum Packages

Listeria monocytogenes counts were determined during storage (82 days, 4°C) in vacuum packages of inoculated bologna and salami slices and after exposure to a simulated dynamic model of the stomach and small intestine. Variables controlled in the model included gastric emptying and gastrointestinal fluid secretion rates, gradual gastric acidification, and intestinal pH maintenance. L. monocytogenes populations increased on bologna and decreased on salami, reaching 8.7 and 1.4 log CFU/g, respectively, on day 82. Inactivation rates (IR) during gastric exposure of bologna and salami ranged from 0.079 (day 14) to 0.158 (day 57) log CFU/g/min and from 0.013 (day 42) to 0.051 (day 1) log CFU/g/min, respectively. On corresponding days, gastric IR for cells on salami were lower than on bologna, suggesting potential protective effects of the former product. However, it is also possible that the low initial L. monocytogenes levels reached with storage of salami (≤2.5 log CFU/g after day 27) may have resulted in slower reductions than in the high levels on bologna. Gradual decline of gastric pH allowed survival in the gastric compartment during the initial stages, which resulted in a large fraction of the cells being delivered into the intestinal compartment. Intestinal IR ranged from 0.003 to 0.048 (bologna) and from 0.002 to 0.056 (salami) log CFU/g/min throughout storage. Although findings indicated potential effects of salami against gastric killing of L. monocytogenes, any effects of the food matrix per se on the gastrointestinal survival of the pathogen were overwhelmed by the high and low contamination levels reached on bologna and salami, respectively, during storage.

Fate of post-processing inoculated Listeria monocytogenes on vacuum-packaged pepperoni stored at 4, 12 or 25 °C

If present, Listeria monocytogenes may not be eliminated during processing of pepperoni or may be introduced during peeling, slicing, or packaging. We evaluated the fate of the pathogen on sliced inoculated pepperoni during vacuum-packaged storage, and potential differences in survival among three types of inocula, including nonacid-adapted, acid-adapted and pepperoni extract-habituated cultures. Commercial pepperoni (two replicates, three samples per treatment) was sliced and inoculated (3 to 4 log CFU/cm 2), before vacuum-packaging and storage for up to 180 days at 4, 12 or 25 °C. Samples were periodically analyzed for pathogen counts (PALCAM agar) and total bacterial counts (tryptic soy agar with 0.6% yeast extract). The pH of the product was relatively stable (4.50–4.81) throughout storage. Overall, levels of the pathogen (all inocula) and total counts decreased continuously during storage at all temperatures. The pathogen died slower at 4 °C than at 12 and 25 °C, while at 12 and 25 °C the death rates were similar. Death rates depended on type of inoculum and generally decreased in the order: acid-adapted, extract-habituated and nonacid-adapted inoculum. At day 60, pathogen levels were below the detection limit and remained undetectable throughout the rest of the 180-day storage period, regardless of inoculum type and storage temperature. Therefore, storage of sliced vacuum-packaged pepperoni, especially at ambient temperature, prior to consumption may reduce the potential risk of listeriosis.

Evaluation of 2-Alkylcyclobutanones in Irradiated Cured Pork Products during Vacuum-Packed Storage

The 2-Alkylcyclobutanones (2-ACBs) content was determined in three Italian cured pork products (salame Milano, coppa, and pancetta) irradiated at different targeted irradiation doses (2, 5, and 8 kGy) during vacuum-packed storage. Among 2-ACBs, three different compounds were investigated, namely, 2-dodecylcyclobutanone, 2-tetradecylcyclobutanone, and 2-(tetradec-5'-enyl)cyclobutanone. 2-ACBs were absent from the nonirradiated samples, whereas their content increased with irradiation dose. Their presence was recorded occasionally at 2 kGy and constantly at higher irradiation doses (5 and 8 kGy). The plot of 2-ACBs content against targeted irradiation doses showed an exponential relationship. The effect of vacuum-packed storage time on the 2-ACBs content was dependent on the irradiation dose. During vacuum-packed storage for up to 60 days, the 2-ACBs content remained unchanged in the cured pork products irradiated at 2 and 5 kGy, whereas a significant increase was observed in the pork products irradiated at 8 kGy.

Sensory and Physiochemical Characteristics of Frankfurters Formulated with Potassium Lactate and Sodium Diacetate before and after Irradiation

Quality attributes were evaluated for irradiated (0, 1.8, or 2.6 kGy) frankfurters formulated with 0% or 3% potassium lactate/sodium diacetate solution and stored aerobically or vacuum packaged at 4 degrees C for 4 or 8 wk, respectively. Quality analyses included descriptive sensory panel, pH, L*a*b* color values, and TBARS determination. Aroma and flavor quality were retained for aerobically stored frankfurters with lactate/diacetate throughout shelf-life. Meaty/brothy complex aroma and flavor, smoke aroma and aftertaste, spice aroma and flavor, astringency, sourness, bitterness, springiness, cohesiveness, and juiciness attributes were lower for aerobically stored frankfurters formulated without lactate/diacetate compared to those with lactate/diacetate toward the end of storage. Sensory color and other quality attributes were minimally influenced by either treatment. Addition of lactate/diacetate and irradiation were also effective shelf-life extenders for vacuum-packaged frankfurters. There were fewer influences on sensory characteristics for vacuum-packaged frankfurters compared to those that were aerobically packaged. However, small yet significant differences were detected by sensory panelists for some aroma and flavor attributes, which remained consistent between treatments throughout storage. Sensory and instrumental color scores varied slightly, but were fairly consistent throughout vacuum-packaged storage. Overall, lactate/diacetate retarded deterioration of frankfurters throughout aerobic storage and helped maintain quality with or without irradiation for vacuum-packaged frankfurters.

Behavior of Listeria monocytogenes at 7 °C in commercial turkey breast, with or without antimicrobials, after simulated contamination for manufacturing, retail and consumer settings

Uncured turkey breast, commercially available with or without a mixture of potassium lactate and sodium diacetate, was sliced, inoculated with a 10-strain composite of Listeria monocytogenes, vacuum-packaged, and stored at 4 °C, to simulate contamination after a lethal processing step at the plant. At 5, 15, 25 and 50 days of storage, packages were opened, slices were tested, and bags with remaining slices were reclosed with rubber bands; this simulated home use of plant-sliced and -packaged product. At the same above time intervals, portions of original product (stored at 4 °C in original processing bags) were sliced and inoculated as above, and packaged in delicatessen bags, simulating contamination during slicing/handling at retail or home. Both sets of bags were stored aerobically at 7 °C for 12 days to simulate home storage. L. monocytogenes populations were lower ( P<0.05) during storage in turkey breast containing a combination of lactate and diacetate compared to product without antimicrobials under both contamination scenarios. Due to prolific growth of the pathogen under the plant-contamination scenario in product without lactate-diacetate during vacuum-packaged storage (4 °C), populations at 3 days of aerobic storage (7 °C) of such product ranged from 4.6 to 7.4 log cfu/cm 2. Under the retail/home-contamination scenario, mean growth rates (log cfu/cm 2/day) of the organism during aerobic storage ranged from 0.14 to 0.16, and from 0.25 to 0.51, in product with and without lactate-diacetate, respectively; growth rates in turkey breast without antimicrobials decreased ( P<0.05) with age of the product. Overall, product without antimicrobials inoculated to simulate plant-contamination and product with lactate-diacetate inoculated to simulate retail/home-contamination were associated with the highest and lowest pathogen levels during aerobic storage at 7 °C, respectively. However, 5- and 15-day-old turkey breast without lactate-diacetate stored aerobically for 12 days resulted in similar pathogen levels (7.3–7.7 log cfu/cm 2), irrespective of contamination scenario.

Effect of Acid Adaptation on Growth during Storage at 10°C and Resistance to Simulated Gastric Fluid of Listeria monocytogenes Inoculated onto Bologna Formulated with or without Antimicrobials

The fate of acid-adapted and nonadapted Listeria monocytogenes inoculated onto bologna slices (formulated with or without antimicrobials) was examined during storage and after exposure to in vitro gastric challenge. Bologna slices formulated with no antimicrobials (control), 3% sodium lactate (SL), or 1.8% SL plus 0.25% sodium diacetate (SD) were inoculated (2 log CFU/cm2) with a 10-strain composite of acid-adapted or nonadapted L. monocytogenes strains. Growth or survival of the two inocula on bologna was evaluated during vacuum-packaged storage (10°C) for up to 36 days. Survival of previously acid-adapted or nonadapted L. monocytogenes on stored bologna exposed to simulated gastric fluid (adjusted to pH 1.0 with HCl) for 20, 40, and 60 min also was determined. As expected, inclusion of antimicrobials in the product formulation inhibited growth of L. monocytogenes during storage of vacuum-packaged bologna compared with growth on control samples. Acid adaptation of L. monocytogenes prior to product inoculation did not affect subsequent survival or growth on bologna or resistance to simulated gastric fluid (P > 0.05). Survival of L. monocytogenes exposed to simulated gastric fluid during storage increased with product age, growth phase of the cells, and possibly age of the cells, particularly for control samples (no antimicrobials), in which the pathogen grew uninhibited to approximately 6 log CFU/cm2 by day 8 of storage. Inhibition of L. monocytogenes growth on product formulated with antimicrobials was associated with only sporadic and small numbers of survivors following exposure of these samples to simulated gastric fluid, especially in samples stored longer. However, cell numbers in these treatment groups before the gastric challenge did not exceed 3.8 log CFU/cm2. Inhibition of growth on product with antimicrobials precluded detection of survivors resistant to the effects of simulated gastric fluid.

Effect of dietary supplementation with vitamin E on characteristics of vacuum-packed lamb

The effect of dietary vitamin E supplementation on lamb during vacuum-packed storage was studied. Thirty-six weaned male Manchego breed lambs were offered four dietary treatments (20, 270, 520 and 1020 mg vitamin E kg−1 feed). Lambs were fed the vitamin E-supplemented diet from 13 until 26 kg live weight. Pieces of M. longissimus dorsi were stored under vacuum at 2 ± 1 °C in the dark and meat quality was assessed after 5, 14 and 28 days of storage. Dietary supplementation significantly increased the α-tocopherol concentration in the muscle (P < 0.001). Initially, lipid oxidation, meat colour and bacterial load were similar in all groups. In meat of non-supplemented lambs the thiobarbituric acid reactive substance value increased throughout storage, whereas in meat of supplemented lambs it did not increase. Meat pigments and discolouration proportion were significantly affected by storage time (P < 0.001). The bacterial load was low initially, but after 28 days of storage it was close to 7 log10 colony-forming units (cfu) cm−2 and Enterobacteriaceae surpassed the limit of acceptability of 2.5 log10 cfu cm−2, making the lamb unsuitable for human consumption. Meat of supplemented lambs displayed less lipid oxidation than that of their non-supplemented counterparts, while meat colour and bacterial load were not affected by supplementation. Copyright © 2007 Society of Chemical Industry

Evaluation of Listeria monocytogenes Populations During the Manufacture and Vacuum-Packaged Storage of Kashar Cheese

Behaviour of Listeria monocytogenes was investigated during the manufacture and storage of Kashar cheese. For this purpose, pasteurized milk was inoculated at four different levels varying between 3 to 6 log cfu ml-1 with the pathogen and its survival was determined in milk, coagulum, curd and cheese received from the production steps and at the 1st and 7th days of the storage. The heat treatment process applied after curd acidification step at 75 °C for 5 min was the most efficient barrier and greatly influenced the viability of the bacteria. Nevertheless this step was not enough to destroy all the bacteria especially when inoculated &gt; 3 log cfu ml-1 levels. For all the groups, this stage resulted in approximately 3 log decrease. Storage at 6 ± 1 °C had no influence on the viability and the count of pathogen remained nearly constant throughout storage. Results of this study indicate that neither production steps nor storage at 6 ± °C for 7 days in vacuum packages was enough to eliminate L. monocytogenes in Kashar cheese particularly if the initial level was high. Thus, in addition to the pasteurization process, hygienic measures should be taken into account to avoid possible secondary contaminations.

Effectiveness of Potassium Lactate and Sodium Diacetate in Combination with Irradiation to Control Listeria monocytogenes on Frankfurters

The use of antimicrobial ingredients in combination with irradiation is an effective antilisterial intervention strategy for ready-to-eat meat products. Microbial safety was evaluated for frankfurters formulated with 0% or 3% added potassium lactate/sodium diacetate solution and inoculated with Listeria monocytogenes before or after treatment with irradiation (0, 1.8, or 2.6 kGy). Frankfurters were stored aerobically or vacuum packaged and L. monocytogenes counts and APCs were determined while refrigerated. The incorporation of lactate/diacetate with or without irradiation had a strong listeriostatic effect for aerobically stored frankfurters. Outgrowth was suppressed and counts were not different from initial counts (5.2 log CFU/frank compared with 5.0 log CFU/frank); however, those without the additive increased steadily (5.4 to 9.3 log CFU/frank). Irradiation treatments alone had higher L. monocytogenes counts after 3 wk. For vacuum-packaged frankfurters, both the addition of lactate/diacetate and irradiation were effective at controlling growth after 8 wk. Large and incremental reductions in total counts were seen for irradiation treatments. Initial counts were reduced by 3 log CFU with the application of 1.8 kGy while 2.6 kGy decreased counts over 5 log CFU. These reductions were maintained throughout storage for lactate/diacetate-treated frankfurters. By 8 wk, L. monocytogenes counts on 1.8 and 2.6 kGy irradiated frankfurters without lactate/diacetate increased to 7.43 and 6.13 log CFU, respectively. Overall, lactate/diacetate retarded the outgrowth of L. monocytogenes on frankfurters throughout aerobic storage and the combination of irradiation and 3% lactate/diacetate reduced and retarded growth of L. monocytogenes, especially during the last 2 wk of vacuum-packaged storage.

Potassium Lactate Combined with Sodium Diacetate Can Inhibit Growth of Listeria monocytogenes in Vacuum-Packed Cold-Smoked Salmon and Has No Adverse Sensory Effects

Growth of Listeria monocytogenes in ready-to-eat fish products such as cold-smoked salmon is an important food safety issue. The objective of this study was to evaluate the antilisterial activity of potassium lactate (PL) in combination with sodium acetate (SA) or sodium diacetate (SDA) in cold-smoked salmon and to determine whether these compounds could be incorporated easily into the formulations and technology currently used by processors. A commercial brine injector was used to inject salmon filets with either saturated saline brine or saturated saline brine supplemented with combinations of PL and SA (PURASAL Opti.Form PA 4) or PL and SDA (PURASAL Opti.Form PD 4). In the brine-injected cold-smoked salmon, 2.1% (water phase) PL and 0.12% (water phase) SDA delayed the growth of L. monocytogenes for up to 42 days of vacuum-packaged storage at 10°C. Storage at 25°C for 6 h resulted in only a 1-log CFU/g increase in L. monocytogenes. Treatments with lower concentrations of PL and SDA or similar concentrations of PL and SA resulted in an extended lag phase and slower growth of L. monocytogenes. It was not possible to incorporate more than 2% (water phase) PL while ensuring a minimum of 3% (water phase) NaCl in the finished product because PL decreased the solubility of NaCl. Sensory analyses revealed that the preservatives did not negatively affect flavor or odor. The combination of PL and SDA is therefore a viable technology for preventing L. monocytogenes growth on cold-smoked salmon.

Chemical quality and sensory attributes of marinated Pacific saury ( Cololabis saira) during vacuum-packaged storage at 4 °C

This study was carried out to evaluate the chemical changes and sensory attributes of Pacific saury ( Cololabis saira), brined (12% NaCl brine solution) or marinated (12% NaCl + 2% acetic acid; or 12% NaCl + 3% acetic acid solutions) followed by vacuum-packaging and storage at 4 °C for 90 days. The chemical analysis revealed a significant reduction in the pH value, total volatile bases nitrogen (TVBN), and trimethylamine (TMA) contents in marinated versus brined fillets. Lipid oxidation, as indicated by the 2-thiobarbituric acid (TBA) values, was significantly delayed in marinated fillets in comparison with the brined fillets. The growth rate of psychrotrophic bacteria was significantly ( P < 0.05) reduced in marinated versus brined fillets. No significant differences were detected for the sensory attributes between the two marinating conditions although the overall acceptability was significantly higher in marinated versus brined fish. Both conditions of the marinating process resulted in an extension of the shelf life of the product to more than 90 days versus only 60 days for the control brined fillets. The study concluded that marination of Pacific saury can delay the undesirable chemical changes, retard lipid oxidation, improve the sensory attributes and extend the shelf life of the product during refrigerated storage.

Fate of Inoculated Escherichia coli O157:H7, Cultured under Different Conditions, on Fresh and Decontaminated Beef Transitioned from Vacuum to Aerobic Packaging

This study evaluated the behavior of Escherichia coli O157:H7 during aerobic storage, after storage in vacuum packages, on beef inoculated with cultures prepared (35°C, 24 h) in tryptic soy broth without dextrose (TSB), nonacid hot water carcass decontamination runoff fluids (washings; pH 6.0; WASH), cells from biofilms formed on stainless steel coupons in WASH (WETB), or WETB dried (25°C, 12 h) before harvesting of cells (DRYB). These inocula were applied to fresh beef pieces (40 cm2), which were then left untreated or treated by immersion in hot water (75°C) followed by 2% lactic acid (55°C; hot water/lactic acid [HW/LA]), for 30 s each. Inoculated samples were vacuum packaged and stored at 0 (30, 60, or 90 days), 4 (7 or 14 days), or 12°C (4 or 8 days) and subsequently transferred to retail packages for aerobic storage at 7°C for 5 days. Populations of E. coli O157:H7, regardless of inoculum type, remained generally unchanged (P > 0.05) after aerobic storage (7°C, 5 days) of untreated or HW/LA-treated beef samples previously stored in vacuum packages at 0 or 4°C. However, reductions in E. coli O157:H7 levels were generally obtained when vacuum packaged, untreated beef samples previously stored at 12°C were transitioned to aerobic conditions. Additionally, despite similar (P > 0.05) levels of E. coli O157:H7 cells of TSB, WASH, WETB, and DRYB origin on vacuum-packaged, untreated samples after 8 days of storage at 12°C, subsequent aerobic storage resulted in larger (P <0.05) reductions of cells of WETB and DRYB origin than for cells of TSB and WASH origin. For HW/LA-treated beef previously stored at 12°C in vacuum packages, populations of E. coli O157:H7 remained largely unchanged after aerobic storage in retail packages. Results thus indicated that aerobic storage of beef (7°C, 5 days) previously stored in vacuum packages at 0 or 4°C did not lead to E. coli O157:H7 population changes, whereas transition from vacuum packages stored under mildly abusive temperature (12°C) to aerobic storage may have caused injury and death to the pathogen.

Effect of vacuum-packaging storage on the quality level of ripened sausages

To investigate the influence of vacuum-packaging on both the sensory properties and the degradation level of their lipid fraction, some ripened sausages (30 days) were further stored for 40 days under vacuum-packaging and compared to sausages kept unpackaged for the same period of time. The same kind of sausages was used in both the trials. As for the sensory properties, after storage the unpackaged sausages showed significantly higher mean scores of red intensity and global flavour than vacuum-packed ones ( p < 0.01 and p < 0.05, respectively) indicating a brighter red colour of meat and a greater overall appreciation by the panelists. Regarding the degradation of the lipid fraction, significantly higher values ( p < 0.01) of the free fatty acids were detected in the vacuum-packed samples, indicating a greater hydrolytic degradation of their lipid fraction as compared to the sausages stored unpackaged. The oxidative degradation of the fatty fraction, measured by the combined use of conventional (determination of peroxide value and TBA test) and non-conventional techniques (HPSEC analysis of the polar compounds of the lipid fraction) showed significant increases during storage for both the storage conditions considered but no significant differences were found between packaged and unpackaged sausages.

Bright Red Color Formation of Cooked Pork Loin Cured with Lactic Acid Bacteria Starter Culture without Adding Nitrite During Low-Temperature Storage

The effects of lactic acid bacteria used as a substitute for nitrite for meat processing were studied. We added lactic acid bacteria starter culture to brine to cure pork loin without nitrite. The cured pork loin was then smoked, sliced, vacuum-packaged, and stored at 2°C for two weeks and at 7°C for additional weeks. A preservative effect of the added lactic bacteria was observed. A homo-fermentative lactic acid bacteria Lactobacillus sakei M32 was a good starter culture to control the microflora of products without nitrite. Bright red color development and propagation between some samples were observed during the cold storage in vacuum packages. This color development is not yet practical for industrial application as a substitute for nitrite. The samples, which had turned clear red in cold storage after two weeks, were further analyzed. In these samples, free arginine markedly decreased, while other free amino acids slightly increased. Although the residual nitrite in the samples was less than one ppm, the degree of color formation of the samples was similar to that of the positive nitrite-added control samples. The results suggested formation of bright red myoglobin derivatives, such as nitrosylmyoglobin from arginine, in the samples.

Effects of supplemental magnesium concentration of drinking water on pork quality1

Thirty-two barrows were used to determine the effects of supplemental Mg in drinking water on pork quality. Pigs were determined to be free of the halothane and Napole mutations and were individually penned. After a 7-d adjustment period, barrows (111 +/- 1 kg BW) were blocked by BW and allotted randomly within block to 0, 300, 600, or 900 mg of supplemental Mg from Mg sulfate/L of drinking water for 2 d before slaughter. Pigs were not allowed access to feed (0.13% Mg) for 15 h before slaughter but continued to have access to experimental water treatments. Pigs were loaded and transported 110 km (1.75 h) to a commercial abattoir and remained in lairage for 5 h before slaughter. The LM was removed 24 h postmortem. Retail storage was simulated for 8 d, and the remaining LM was vacuum-packaged for 25 or 50 d at 4 degrees C. Plasma Mg concentration increased linearly (P = 0.001) with Mg supplementation; however, Mg concentration of the LM was not affected (P = 0.99) by Mg supplementation. Surface exudate, drip loss, and retail fluid loss of the LM were not affected (P > 0.10) by Mg. Lightness (L*) and redness (a*) of the LM were not affected (P > 0.10) by Mg, with the exception of initial redness (cubic; P = 0.05). Pigs supplemented with 300 or 900 mg of Mg/L had lower yellowness (b*) values of the LM displayed for 0 to 6 d than pigs supplemented with 0 or 600 mg of Mg/L (cubic; P < 0.05). Lightness of the LM after 25 (quadratic; P = 0.03) or 50 (quadratic; P = 0.04) d of vacuum-packed storage was greater at 300 and 600 mg of Mg/L than at 0 or 900 mg/L. Yellowness tended to be greater after 50 d, but not after 25 d, of vacuum-packaged storage for 300 or 600 mg of Mg/L compared with 0 or 900 mg/L (quadratic; P = 0.08). Oxidation of the LM, determined by thiobarbituric acid reactive substances after 4 d of retail storage, increased linearly (P = 0.05) as Mg increased in the drinking water. Furthermore, oxidation of the LM after 8 d of retail storage tended to increase linearly (P < 0.10), primarily because of the high oxidation of LM from pigs supplemented with 900 mg of Mg/L compared with controls (224 vs. 171 +/- 19 microg/kg, respectively). Oxidation of the LM was greater for pigs supplemented with 300 or 900 mg/L compared with 0 or 600 mg of Mg/L (cubic; P < 0.06) after 25 d of vacuum-packed storage. Magnesium did not improve pork quality characteristics of practical significance in pigs without the halothane and Rendement Napole mutations.

Effect of calcium chloride, zinc chloride, and water infusion on metmyoglobin reducing activity and fresh lamb color

Calcium chloride (CaCl2), zinc chloride (ZnCl2), or water infusions were used to investigate the biochemical factors that affect fresh lamb color, and to examine the role of metmyoglobin-reducing activity in regulating this important quality attribute. Immediately after exsanguination, lamb carcasses (n = 6 per treatment) were infused (10% of BW) with 0.3 M CaCl2, 0.05 M ZnCl2, or water via a catheter inserted into the left carotid artery. The right LM was excised at 24-h postmortem and divided into two halves. The caudal portion was cut into 2.5-cm-thick chops and displayed for 6 d under 1,076 lx of white fluorescent lighting at 2 degrees C, whereas the cranial half was vacuum-packaged and stored at 2 degrees C for 3 wk before retail display. Objective color measurements and samples for biochemical analysis were taken at 0, 1, 3, and 6 d of display. In infused carcasses, pH decline was more rapid (P < 0.05) than in untreated controls, and it was greatest for CaCl2-infused carcasses. Calcium chloride-infused carcasses had lower (P < 0.01) NAD and higher (P < 0.001) NADPH concentrations than water- and ZnCl2-infused or untreated control carcasses. The negative effects of calcium infusion on fresh lamb color, higher (P < 0.01) metmyoglobin accumulation rate, and lower (P < 0.01) L*, a*, and b* color measurements could be explained by the lower amounts of unbound water (P < 0.01), shorter sarcomere length (P < 0.01), lower NAD concentrations (P < 0.01), and higher lipid peroxidation (P < 0.01). Zinc and water-infusions produced less (P < 0.01) lipid oxidation and improved the color and color stability of fresh lamb (P < 0.001). Rate of lipid oxidation in LM chops was greater (P < 0.01) after 3 wk of vacuum-packaged storage than 24-h postmortem. Metmyoglobin-reducing activities (sarcoplasmic and myofibrillar) were decreased in response to infusion treatments (P < 0.001), and ZnCl2 infusion resulted in the lowest metmyoglobin-reducing activities (P < 0.001). A significant association between the myofibrillar metmyoglobin-reducing activity and lipid peroxidation was observed, but metmyoglobin-reducing activities were not associated with any improvement in lamb color. Strategies to increase the antioxidant levels in lamb are very important to improve lamb quality, especially during vacuum-packaging storage.