Effect of Potassium Sorbate and Vacuum Packaging on the Quality and Microflora of Dry-Cured Intact and Boneless Hams

Intact and boneless hams were dry-cured and aged with and without potassium sorbate or vacuum packaging. Sorbate had no effect on yield but dry sorbate generally improved panel scores in boneless hams. Vacuum packaging eliminated further weight loss, decreased visual appraisal scores in intact hams but had little effect on sensory scores. After 3 months of aging, aerobic and staphylococci counts were as much as 7 logs lower in nonvacuum packaged controls than in either nonvacuum or vacuum packaged sorbate treated intact hams. Counts within all vacuum packaged groups were similar. Yeast and mold counts were lower in sorbate treated than in non-sorbate treated vacuum packaged hams. After aging, coagulasenegative staphylocci were the predominant species.     

Effects of Vacuum Packaging and Potassium Sorbate on Yield, Yeast and Mold Growth, and Quality of Dry-Cured Hams

Two trials were conducted. In the first trial hams were cured by a standard process and aged 1 month at 24°C. Group I hams were not packaged or treated. Group II hams were vacuum packaged and Group III hams were dipped in a 2.5% potassium sorbate solution and also vacuum packaged. All hams were examined after 1 month and the treated group was dipped in a 5% sorbate solution, vacuum packaged and aged an additional 2 months. Vacuum packaging practically eliminated further weight loss while potassium sorbate reduced but did not eliminate mold growth. In the second trial hams were again cured by a standard process and aged at 24°C until they were officially country hams (18% weight loss). Group I hams were not treated whereas group II hams were dipped in a 10% potassium sorbate solution. All were vacuum packaged. After aging one month they were unpacked, weighed, and examined for molds. No significant weight loss had occurred but mold counts were lower in the dipped group. The dipping procedure was reversed so that group I hams were treated and group II hams were not treated. All hams were again vacuum packaged and held a second month. No additional weight loss was noted. Mold growth, though not eliminated, was minimal, and visual and aroma scores for the cut hams were similar and highly acceptable. Tenderness, flavor, saltiness, and overall satisfaction scores for cooked slices were similar and highly acceptable. In general, mold growth can be greatly reduced by the use of potassium sorbate and weight loss can be controlled by vacuum packaging.     

Microbiological and physicochemical properties of fresh retail cuts of beef packaged under an advanced vacuum skin system and stored at 4 degrees C

The effect of an advanced vacuum skin packaging system on the microbiological and physicochemical properties of fresh retail cuts of beef (including meat portions from six different anatomical regions) stored at 4 degrees C was compared with the effect of traditional vacuum packaging. The vacuum skin packaging system whose effect on meat quality was evaluated in this work displayed two remarkable features: (i) the instantaneous heating of the lower surface of the upper film of the package before the film descended over the meat surface and (ii) the tight disposition of the plastic film on the meat surface, which avoided wrinkles and purges. Throughout storage at 4 degrees C, rates of bacterial growth were statistically significantly slower in beef portions processed with the vacuum skin packaging system than in those processed with traditional vacuum packaging, with average differences of 2.07, 1.60, and 1.25 log CFU/g in counts of aerobic mesophiles, anaerobes, and lactic acid bacteria, respectively. pH values were statistically significantly lower for beef portions packaged with the vacuum skin system than for those that were vacuum packaged in the traditional manner, probably because of the relative predominance of lactic acid bacteria observed in such samples, which coincided with both higher meat firmness values and a slower meat tenderization process. The vacuum skin system prevented the appearance of undesirable coloration on the meat surface and also significantly improved the commercial color of the meat as determined on the basis of luminosity (L*) and the redness (a*). Overall, the quality (as determined by microbiological and physicochemical analyses and by visual examination) of fresh retail cuts of beef packaged with the vacuum skin system and stored at 4 degrees C was higher than that of meat samples processed with the traditional vacuum-packaging system.     

Reduction of Brochothrix thermosphacta and Salmonella Serotype Typhimurium on Vacuum-Packaged Fresh Beef Treated with Nisin and Nisin Combined with EDTA

ABSTRACT: The effect of nisin and nisin/EDTA followed by vacuum packaging on the reduction of Brochothrix thermosphacta and Salmonella typhimurium counts on beef was investigated. Beef cubes, inoculated with either bacteria, were dipped in nisin, or nisin combined with EDTA solutions, vacuum packaged, and stored at 4 °C for up to 25 d. Growth of B. thermosphacta was completely inhibited by nisin and nisin/EDTA by up to 6.76 log₁₀ CFU/ml. However, neither treatment showed significant effects against S. Typhimurium. Thus, nisin or nisin/EDTA treatment, followed by vacuum packaging under refrigerated conditions could increase the shelf life of fresh beef by inhibiting the growth of B. thermosphacta , an important spoilage organism in beef.     

Characteristics of Dry-Cured Hams as Affected by Needle Tenderization and Vacuum Packaging

Needle tenderization of skinned hams accelerated salt absorption and weight loss and shortened curing time for dry-cured hams. Vacuum packaging of hams after they achieved an 18% weight loss prevented most additional weight loss thus yielding a higher percentage of moisture and a lower percentage of salt than in nonpackaged hams. Total bacterial and lactobacilli counts were higher in packaged hams but did not affect internal appearance scores or sensory evaluation scores. In general, the use of needle tenderization and vacuum packaging was helpful in reducing curing and aging time and in controlling yields in dry-cured hams.     

不同包装方式对猪背最长肌冷却成熟期间品质变化的影响

对猪背最长肌分别进行普通托盘和真空包装2种处理,研究了4℃成熟期间菌落总数、色泽、汁液流失、煮制损失、pH和乳酸含量的变化。结果表明:普通托盘包装的肉汁液流失低,L*较高,但微生物菌落总数增长较快;真空包装可有效抑制微生物菌落总数增长,但汁液流失较高、肉色L*较低。2种包装方式下猪背最长肌煮制损失没有显著差别,并且pH和乳酸在冷却成熟期间亦无显著变化。     

EFFECT OF FREEZING AND PACKAGING METHODS ON SURVIVAL AND BIOCHEMICAL ACTIVITY OF SPOILAGE ORGANISMS ON CHICKEN

SUMMARY— A study was conducted to determine effects of freezing, thawing, and subsequent holding at about 5°C on survival or growth of aerobic bacteria on chicken packaged with various materials. Production of fluorescent pigment, and extracellular proteinase and lipase activities were used as indices of the ability of the organisms to produce spoilage. Growth of bacteria was determined by colony counts. Assays for proteolysis were made by means of a dye binding method; lipolysis of chicken fat was determined by titration of free fatty acids. Fluorescent pigment formation was evaluated by means of a photofluorometer. The influence of availability of oxygen on proteolytic and lipoytic spoilage of poultry was studied after chicken was packaged with materials having high or low oxygen permeability and by vacuum packaging. Fluorescent pigment production, proteofytic and lipolytic spoilage of chicken stored at 5°C was directly related to the availability of oxygen provided by the packaging procedure. Bacterial numbers paralleled increases in biochemical indices of deterioration. Freezing of chicken at −29°C for 35 days followed by defrosting and refrigerated storage increased the proportion of biochemically active psychrophiles on the surface of the meat. Vacuum packaging generally limited amount of spoilage as measured by the criteria specified. When samples were analyzed after alternate freezing and thawing, total aerobic bacterial counts were only slightly different from those on chicken frozen continuously for 22-25 days.     

VACUUM PACKAGING OF LAMB. 1. Microbial Considerations

SUMMARY –Paired loins from 148 lamb carcasses were utilized to determine the subsequent case-life of chops from loins that had been stored in vacuum packages. Bacterial samples which were obtained from the surface of the longissimus muscle were used to evaluate the retail case-life of loin chops. Longer periods of storage in vacuum packages were associated with higher initial psychrotrophic counts for subsequent loin chops. Comparisons between vacuum packaged loins that were stored at 0°C vs. 7°C indicated that storage temperatures of 7°C were more favorable for psychrotrophic bacteria growth and thus resulted in decreased subsequent case-life for chops from these loins. 8 days appears to be a reasonable maximum period for the storage of loins in vacuum packages. Fresh chops that were fabricated 8 days postmortem and displayed immediately exhibited an advantage of 1½1/4 days of increased case-life in comparison to those chops from loins which were vacuum packaged 8 days postmortem, stored under vacuum for 8 days, fabricated and subsequently displayed. The average case-life of fresh chops was 3½1/2 days when stored in a retail case at 0°C. The results of the present study indicate that vacuum packaging of lamb loins may be feasible; however, unless low storage temperatures are maintained and the storage interval is short, the retail case-life of chops will be reduced.     

Effects of Packaging Method, Display Light and Storage Time On The Microbial Growth and Rancidity of Fresh Pork

Effects of display light, packaging methods and storage time on total aerobic, lipolytic and proteolytic counts and oxidative rancidity of fresh pork stored at 2 ± 1° C were studied at the initial, 7th, 14th and 21st day of storage. Display light significantly increased the total aerobic psychrotroph count. Effects on lipolytic and proteolytic psychiotroph counts were not significant. No anaerobic psychrotrophs were encountered. Total and proteolytic counts of PVC film overwrapped chops and proteolytic and lipolytic psychrotroph counts of chops vacuum packaged accelerated linearly with time. Increases in lipolytic psychrotroph count of PVC packaged and total aerobic psychrotroph count of vacuum packaged chops were quadratic. TBA number and rancid odor scores were not significantly affected by treatments.     

Irradiated Ground Beef: Sensory And Quality Changes During Storage Under Various Packaging Conditions

Ground beef patties (irradiated with 2 kGy and nonirradiated) were packaged using oxygen permeable (polyolefin) or oxygen impermeable material (polyethylene). Samples were irradiated in air and stored in air; irradiated under vacuum and stored under vacuum; or irradiated under vacuum and stored in air. Changes in flavor, texture, juiciness or aftertaste were evaluated after either 1 or 7 days storage at 25°C prior to cooking. Irradiated "Vac/Air" samples were more tender, irradiated "Vac" samples were more moist, and irradiated "Air" samples had the least aftertaste. A 3 log₁₀ reduction in total aerobic counts was detected immediately after irradiation. No difference in lipid oxidation was found within the first week of storage, regardless of packaging atmosphere. Shelf life of ground beef patties was extended 55 days at 4°C.     

Effects of processing and packaging on vitamin C and β-carotene content of ready-to-use (RTU) vegetables

High pressure liquid chromatographic methods were used for measurement of the concentration of vitamin C and β-carotene in broccoli and green pepper. The effects of processing, packaging and storage on the levels of these nutrients in both unprocessed and processed ready-to-use (RTU) vegetables were determined. Systems investigated included: (a) unpacked and pillow packaged broccoli, and (b) unpacked, pillow, partial vacuum, and total vacuum packaged green pepper. There was a statistically significant decrease in vitamin C over a 10 day storage period of unpacked and packaged vegetables including all four packaging systems (P<0.001, overall average decrease of 11%). The overall loss of β-carotene during the 10 day storage period was not statistically significant (P=0.14). Although there was a significant loss in vitamin C during storage, in most cases there was no difference in loss of vitamin C or β-carotene between the processed and unprocessed vegetables, and the packaging systems.     

Effect of modified atmosphere packaging on the microbiological and sensory quality on a dry cured beef product: "Cecina de león"

The aim of this study was to investigate the shelf-life of commercial “Cecina de León” (CL) packaged in vacuum (VP) and in CO₂/N₂ atmospheres (20/80% CO₂/N₂ and 80/20% CO₂/N₂). Packaged product was stored at 6 °C, measuring microbiological, physico-chemical and sensory parameters during 210 days. The values obtained for mesophilic aerobic, anaerobic and psychrotrophic counts did not vary in both the vacuum and the gas packaged samples after 210 days of storage. Enterobacteria and enterococci were always below the detection limit, and in the gas-packaged CL, pseudomonad numbers were significantly inhibited. No changes were observed in the counts of the typical microflora of CL (Lactic Acid Bacteria, yeasts and moulds and Micrococcaceae) up to 210 days and no differences (p > 0.05) were found between the counts in the VP and in the gas-packaged samples. A pronounced initial fading was observed in redness (a^∗) within the first 15 days in the VP samples and within the second month in the gas-packaged samples attributed to the presence of white film on surface of CL portions. No differences were observed (p > 0.05) in texture parameters evaluated between packaging methods during storage, and the values found are within the range for CL not packaged. The sensory properties of CL stored in 20/80% CO₂/N₂ were slightly less acceptable than the samples packed under vacuum and under 80/20% CO₂/N₂ at 210 days of storage. It is concluded that no clear advantage of the gas packaging was observed compared to the VP of “Cecina de León”.     

SURVIVAL AND GROWTH OF LISTERIA MONOCTYOGENES ON BEEF TISSUE SURFACES AS AFFECTED BY SIMULATED PROCESSING CONDITIONS

The numbers of Listeria monocytogenes Scott A were followed on experimentally inoculated lean and fat beef tissue handled under a variety of simulated storage conditions at 5°C, including high and low moisture storage, simulated spray chilling, and vacuum packaging. Under high moisture storage conditions, L. monocytogenes increased approximately 3 log cycles on both lean and fat tissue after 21 days. Similar growth was observed with vacuum packaged lean tissue. Under dry storage conditions, the population decreased approximately 2 logs during the first 14 to 21 days, but the counts remained constant for 42 days. Simulated spray chilling did not affect the growth or survival of L. monocytogenes on either lean or fat tissue .     

Microbial dynamics in industrial blue veined cheeses in different packaging

The aim of this study was to evaluate the effects of packaging on the microbiota of blue veined cheeses. The microbial dynamics of portions of industrial cheeses packaged under vacuum in different films and whole cheeses in aluminium foil was compared using culture-dependant and metagenomic approaches. There was no oxygen in the packaging and CO₂ concentrations were between 5 and 12%. The composition of the lactic acid bacteria population did not change significantly during storage; it varied more according to factory of origin. Vacuum packaging hampered the growth of aerobic bacteria (Brevibacterium, Arthrobacter, Brachybacterium) and Gram-negative bacteria more than did stretch film. In vacuum-packed cheese portions, Staphylococcus and/or Brevibacterium and Arthrobacter were the dominant Gram-positive catalase-positive populations, depending on the factory of origin. Cheese packaged under vacuum had a lower pH than cheese in aluminium foil or stretch film.     

微冻及真空包装对原汁整壳贻贝贮存期品质的影响

为研究微冻及真空包装对原汁整壳贻贝贮存期品质的影响,将原汁整壳贻贝进行真空包装及普通包装,于4和-3℃下进行贮存,对样品的感官评分、汁液流失率、pH、电导率、挥发性盐基氮(total volatile basic nitrogen,TVB-N)、2-硫代巴比妥酸(2-thiobarbituric acid,TBA)、菌落总数等指标的变化规律进行分析。结果表明:原汁整壳贻贝在贮藏过程中,随着时间的延长,感官评分下降;pH先降低后升高;汁液流失率、TVB-N、TBA、电导率和菌落总数均随贮存时间的延长而增长。-3℃微冻的保鲜效果明显优于4℃冷藏(P<0.05),真空包装的保鲜效果明显优于普通包装(P<0.05),-3℃微冻结合真空包装保鲜效果最佳,能显著延缓原汁整壳贻贝感官性状的下降(P<0.05),抑制汁液流失率、电导率、TVB-N值、TBA值的上升(P<0.05),延缓pH最低点出现的时间(P<0.05),抑制菌落总数的增长(P<0.05)。综合比较分析,4℃普通包装、4℃真空包装、-3℃普通包装、-3℃真空包装的货架期分别为6、15、15和60 d。因此,微冻结合真空包装能较好维持原汁整壳贻贝的感官性状及品质稳定性,有效延长货架期。     

MICROBIAL GROWTH IN PACKAGED FRESH ASPARAGUS

The effects of storage temperature and time on the microflora of fresh, vacuum packaged, and modified atmospheres packaged asparagus (Asparagus officinalis) were analyzed. Total aerobic mesophilic, psychrophilic, lactic acid bacteria, Enterobacteriaceae, and yeast and molds were determined as a function of time. The effect of washing on the original microflora of the asparagus and the growth of the different microbial groups during the storage time were checked. From day 8, a progressive increase in the mesophile and psychrophile counts in both types of packaging was observed. At the end of the experiment (day 21), the mesophile and psychrophile counts were all 10⁷ CFU/g, for both types of packaging. In the vacuum packaging, the final enterobacteria counts (2.5 × 10² CFU/g) and yeast and molds (10 CFU/g) were lower than in the polyethylene bag packaged asparagus, which showed enterobacteria counts of 7.3 × 10⁴ CFU/g) and yeast and mold counts of 2.3 × 10⁴ CFU/g. The non-packaged asparagus showed low counts from the fourth day due to their heavy dehydration caused by the low relative humidity in the storage chamber.     

Effect of the inoculation of a starter culture and vacuum packaging (during resting stage) on the appearance and some microbiological and physicochemical parameters of dry-cured ham

The effect of the inoculation of a starter culture and vacuum packaging (during the resting stage) on dry-cured ham appearance, microbiological and physicochemical parameters was studied. Half of the 36 processed hams were inoculated, after salting, with a commercial starter culture containing lactic-acid bacteria, Gram-positive catalase-positive cocci and yeasts. 18 hams per group (inoculated and non-inoculated) remained vacuum packaged during resting. Microbiological analyses were carried out on the lean surface during processing, on subcutaneous fat tissue at the drying stage and on lean tissue in the finished product. Appearance was evaluated during processing. Physicochemical analyses (NaCl, H(2)O, proteolysis index, a(w)) were done on Semimembranosus and Biceps femoris in the final product. Inoculation caused a reduction of mould growth and oil drip. Vacuum packaging induced increased proteolysis and increases in all microbial counts and a reduction of oil drip, mould growth and weight loss during processing.     

DISTRIBUTION PACKAGING METHOD AND STORAGE TIME EFFECTS ON THE MICROBIOLOGICAL CHARACTERISTICS AND INCIDENCE OF THE PATHOGENS LISTERIA MONOCYTOGENES AND SALMONELLA IN PORK1

Microbiological and yield characteristics were determined on bone-in pork loins and Boston butts (n = 65 each) that were selected from a commercial facility and subjected to one of three packaging treatments: (1) paper wrapped, (2) modified atmosphere packaging (66% O, 2.26% CO₂ and 8% N₂), and (3) vacuum packaging. Cuts were stored up to 21 days at 0 ± 2C for yield characteristics and an added 28 and 35 days for microbiological characteristics. Treatment and storage effects on the incidence of the pathogens Listeria monocytogenes, Salmonella and numbers of aerobic bacteria, lactic acid bacteria and coliforms were determined. The amount of purge was variable (100 to 500 g) among packaging treatments. The vacuum packaged and modified atmosphere packed pork loins and butts had lower aerobic plate counts (P < .05) compared with the paper wrapped loins and butts. The numbers of Listeria species decreased at a greater rate for the vacuum packaged and modified atmospheric packaged pork loins compared with the paper wrapped loins. No Salmonella were found on meat from any packaging treatment or storage time. The microbial quality of pork loins and butts can be improved by using vacuum packaging compared with paper wrapping or modified atmosphere packaging.     

Extension of the chilled storage life of smoked blue cod (Parapercis colias) by carbon dioxide packaging

Commercially prepared smoked blue cod ( Parapercis colias ), packaged aerobically, under vacuum and in carbon dioxide controlled atmosphere packs, was stored at + 3°C and - 1.5°C. Product stored aerobically on overwrapped polystyrene trays spoiled by 14 and 28 days respectively, and that in vacuum packs spoiled by 14 and 35 days respectively, when held at 3°C and - 1.5°C. In contrast, product in carbon dioxide packs remained acceptable until the 3°C and - 1.5°C storage trials ended after 49 and 113 days respectively. Microbial spoilage was first evident in overwrapped product stored aerobically and in vacuum-packed product as offensive putrid amine-like odours on pack opening. These odours were associated with the development of a predominantly Gram-negative spoilage microflora. Extension of product life afforded by the use of carbon dioxide controlled atmosphere packaging is attributable to a significant extension of the lag phase before spoilage microflora proliferation commenced and to the selection of a low-spoilage-potential lactic-acid-bacteria-dominated flora. Although the use of carbon dioxide packaging offers an export potential for chilled smoked blue cod, caution must be advocated until product safety, in respect to the growth of cold tolerant pathogens in the case of temperature abuse (>3°C), can be more fully evaluated.     

Microbiological,physicochemical and sensory characteristics of Cameros cheese packaged under modified atmospheres

This study evaluated the shelf-life quality of Cameros cheeses packaged under modified atmospheres. Five different modified atmosphere conditions were studied (carbon dioxide/nitrogen mixtures and vacuum). Control cheeses were packaged in air. The product stored at 3–4°C was evaluated periodically to investigate its sensory quality, microbiological condition and physicochemical characteristics. Weight loss and pH evolution were similar in vacuum and air packaging. Cheeses packaged in 100% CO₂showed the greatest weight losses and lower pH values. CO₂reduced proteolysis and lipolysis during storage in all conditions studied. Fat acidity and NPN/TN values were slightly higher in vacuum than in CO₂, but lower than in air. Modified atmosphere packaging presented an extended shelf life. Those containing CO₂reduced the growth rate of mesophiles, psychrotrophs, Enterobacteriaceae and coliforms, which was lower when the CO₂concentration increased. The lowest microbial counts were at 100% CO₂while vacuum conditions presented microbial counts only slightly lower than the controls. Salmonella spp.,Staphylococcus aureus and Listeria spp. were not found in any of the samples. Faecal coliforms, moulds and yeasts were not detected under CO₂atmospheres or in vacuum. After 7 days of storage, the sensory characteristics of the control cheeses were unacceptable in all the parameters studied. However, the overall score for cheeses stored in 40% and 50% CO₂did not change substantially, retaining a reasonable acceptability until the end of the storage period. The 100% CO₂atmosphere had a very negative effect on sensory quality. With regard to Cameros cheese, packaging in 50%CO₂/50%N₂and 40%CO₂/60%N₂are the most effective for extending shelf life and retaining good sensory characteristics.