Vacuum-packaged Products Research Articles

The Influence of Selected Herb Additives on the Organoleptic and Antioxidant Properties and Storage Stability of Frozen Homemade Tofu

The aim of this study was to check the impact of the addition of selected flavoring herbs on the organoleptic and antioxidant properties of homemade tofu, as well as the possibility of its storage extension by freezing. The optimization of homemade tofu production based on organic soy and the enrichment (2% w/w) of obtained tofu with dried plant additives (wild garlic, basil, Herbes de Provence, black cumin seeds, and dried cranberries) was performed. The manufactured tofu was compared to commercial tofu (control) in terms of antioxidant activity, total polyphenol content, and polyphenol profile using thin-layer chromatography (HPTLC). Moreover, the texture profile and organoleptic assessment of the compared products were performed. The antioxidant and texture parameters were also controlled in tofu fixed by different methods: cold herbal infusion and prolonged freezing of vacuum-packed products. It was shown that homemade tofu was characterized by better sensory and texture properties than commercial product. Moreover, the introduction of plant additives to tofu increased the antioxidant activity and the content of polyphenols in the final product; the greater the activity of the herbs used, the higher the degree of tofu enrichment was achieved. In terms of all analyzed parameters, cranberries and Herbes de Provence additives to tofu were found to be the first choice. It was found that the addition of herbs to tofu allowed us to create new sensory features, enhanced the pro-healthy value, and extended the storage time. Due to no significant changes in texture and antioxidant properties of frozen tofu, as well as its acceptable microbial quality, freezing vacuum-packed tofu can be recommended as a beneficial way to extend the storage time at home condition. The addition of herbs allows for the design of new versions of tofu in accordance with consumer preferences, and the proposed packaging method can be applied on an industrial scale.

Development, Characterisation, and Consumer Acceptance of an Innovative Vegan Burger with Seaweed

What consumers choose when purchasing food is of most importance to promote sustainability. The consumption of more sustainable foods should be stimulated, for example, by using more sustainable ingredients and by consumer education. Therefore, an innovative and highly nutritious vegan burger with seaweed (VBS) was developed using sustainable ingredients, such as pulses—grass pea (Lathyrus sativus L.) and chickpea (Cicer arietinum L.)—and the seaweed Dulse (Palmaria palmata L.) from aquaculture. VBS was analysed for its physico-chemical and nutritional characteristics, including antioxidant activity (DPPH, TPC) and fatty acid and mineral element profiles. Shelf life and consumer acceptability were determined. The VBS was shown to be a source of protein (8.01 ± 0.14% fresh weight (FW)), fibre (5.75% FW), and mineral elements, such as P, Fe, rich in Mg, Mn, and Cu, while having low sodium content. Moreover, it presents a low sugar content. Furthermore, no antioxidant activity was detected. The pasteurised and vacuum-packed product had a shelf life of 90 days and was well accepted by consumers (64.0% acceptance). It may be concluded that an innovative VBS, nutritionally rich and with a shelf life of 90 days, was developed and well accepted by consumers, which is a good addition to a rich and diverse diet.

Evaluation of vacuum packaging for extending the shelf life of Sardinian fermented sausage

Salsiccia sarda or Sardinian fermented sausage is a traditional dry-fermented sausage included in the list of traditional food products of Sardinia (Italy). At the request of some producing plants, the possibility of extending the shelf life of the vacuum-packed product up to 120 days was evaluated. Manufacturing of 90 samples, representing 3 different batches of Sardinian fermented sausage was carried out in two producing plants (A and B). In the packaged product and subsequently every 30 days for four months (T0, T30, T60, T120), the following analyses were conducted on all samples: physicochemical characteristics, total aerobic mesophilic count, Enterobacteriaceae count, detection of Listeria monocytogenes, Salmonella spp., mesophilic lactic acid bacteria, and coagulase-positive Staphylococci. Moreover, surfaces in contact and surfaces not in contact with food were sampled in both producing plants. Sensory profile analysis was also performed for every analysis time. At the end of the extended shelf life, pH values were equal to 5.90±0.11 (producing plant A) and 5.61±0.29 (producing plant B). Water activity mean values at T120 were 0.894±0.02 (producing plant A) and 0.875±0.01 (producing plant B). L. monocytogenes was detected in 73.3% (33/45) of the samples from producing plant A, with mean levels of 1.12±0.76 log10 CFU/g. In producing plant B, L. monocytogenes was never detected. Enterobacteriaceae were detected in 91.1% (41/45) of samples in producing plant A with mean values of 3.15±1.21 log10 CFU/g, and in 35.5% (16/45) samples in producing plant B samples with mean values of 0.72±0.86 log10 CFU/g. Salmonella and Staphylococcus aureus were never detected. Regarding environmental samples, the sites that were most contaminated by L. monocytogenes were the bagging table (contact surface) and processing room floor drains (non-contact surface) with a prevalence of 50% each (8/16 positive samples for both sampling sites). Sensory analysis results showed that at T30 the overall sensory quality was at its highest; moreover, the visual-tactile aspect, the olfactory characteristics, the gustatory aspects, and the texture showed significant differences in samples throughout the shelf life, with a decreased intensity at 120 days of storage. Overall, the quality and sensory acceptance of the vacuum-packed Sardinian fermented sausage were not affected until 120 days of shelf-life. However, the possible contamination by L. monocytogenes calls attention to the hygienic management of the entire technological process. The environmental sampling was confirmed as a useful verification tool during control.

Diagnostic capabilities of modern methods of determination pathogenic listeria in meat products

Annual reports on the morbidity of the adult population report outbreaks of listeriosis caused by Listeria monocytogenes with clinically pronounced febrile gastroenteritis. The main transmission route to humans is believed to be through consumption of contaminated food, especially ready-to-eat meat products. Rapid and specific detection of L. monocytogenes in food is critical for ensuring the safety of consumers. The aim of this work was to study the occurrence of L. monocytogenes in vacuum-packed meat products using modern diagnostic methods. In total, 60 vacuum-packed meat products were studied using real-time PCR (iQ-Check™ realtime PCR kit), immunoassay (VIDAS LMO2 test) and culturing. Thirty-two of 60 (53%) vacuum-packed meat products were L. monocytogenes positive by real-time PCR. The occurrence was especially high in heat-treated sausages (80%). Only two products (two bacons) were VIDAS and culture positive. Additionally, L. monocytogenes was isolated from one heat-treated sausage, which was VIDAS negative. All VIDAS and culture-positive samples were also PCR positive. In two (12%) out of 17 vacuum-packed ready-to-eat products, the number of L. monocytogenes was over 100 cfu/g demonstrating that the shelf life assigned to some vacuum-packed products is not appropriate. Real-time PCR based on iQ-Check™ realtime PCR kit was shown to be very sensitive to detect L. monocytogenes in foods and thus a useful tool for screening.

A quantitative risk assessment of Listeria monocytogenes from prevalence and concentration data: Application to a traditional ready to eat (RTE) meat product

Ready to Eat (RTE) cooked meat products are among the most consumed RTE food subcategories in the EU/EEA. They are also associated with the highest number of identified listeriosis cases per year (>850), thus posing a public health risk especially among the susceptible population. This study estimated the risk of listeriosis from Italian head cheese (Coppa di Testa) consumption using a Quantitative Microbiological Risk Assessment (QMRA) based on data of prevalence and starting concentrations of Listeria monocytogenes in the product during a 3-year period (n = 1568). A consumer survey (n = 162) was conducted to provide information on domestic storage time and consumption habits, and storage conditions were determined from recordings of temperatures of domestic refrigerators (n = 57). A probabilistic model was designed for the evaluation of the growth of L. monocytogenes at each stage of the product pathway from production to consumption, using Monte Carlo simulations and employing the @Risk software. Risks associated to consumption of vacuum-packed and sliced-at-retail head cheese were assessed: The model predicted that the risk of listeriosis per serving of vacuum-packed product was in the 10−4 and 10−6 range (mean) for the high-risk and general populations respectively, and listeriosis cases were estimated to be greater than those due to consumption of sliced product (with risks in the range of 10−7 and 10−8). Overall, the model predicted that the mean number of listeriosis cases ranged from 0.001 to 0.24 and from 0.06 to 10 per one hundred thousand people, for the healthy and the high-risk population, respectively. Scenario analyses indicated that better control of the temperature of domestic refrigerators is effective in reducing the predicted risk of listeriosis for the longer stored vacuum-packed product by ~80 % for both the healthy and high-risk populations, whereas a shorter use-by-date of 30 days is an effective risk mitigation measure for both types of packed product. Model assumptions, as well as data gaps are discussed.

The Evaluation of Oyster Marinating (Crassostrea Gasar) and Pasteurization Process in Vacuum Packaging during Storage

ABSTRACT The evaluation of oyster marinating (Crassostrea gasar) and pasteurization process in vacuum packaging during storage. The aim of this study was to establish better conditions for marinating and pasteurization for oysters (Crassostrea gasar) and to evaluate their shelf life. Microbiological, physicochemical and sensory analyzes were carried out on the oysters and on the optimized product. In the vacuum-packed product, under refrigeration, pH, water activity (aw), total volatile bases (N-TVB) and texture analyzes were performed, every 7 days for 35 days. Oysters had a high protein, mineral and amino acid content and a low lipid content. Planning 23 and 221 hour, 2.5% acetic acid, 1% NaCl and pasteurization was 62°C/2 min. Sensory analysis achieved acceptability above 80%. Marinated oysters remained suitable for consumption for 21 days, being an alternative to extend the shelf life and add value.

Microplastics in vacuum packages of frozen and glazed icefish (Neosalanx spp.): A freshwater fish intended for human consumption.

It is widely accepted that human is exposed to microplastics through food consumption, however data occurrence in foodstuffs are still little and basically limited to seafood. In this study, the presence of microplastics was investigated in icefish (Neosalanx spp.) samples sourced from various mass-market retailers in Italy, supplied as frozen, glazed and vacuum-packed product. Icefish is a small freshwater fish widely imported in Europe from China as surrogate of other fish species subjected to commercial restriction, consumed whole after cooking in several culinary preparation. The samples (~10 g of icefish from each of the 40 packs tested) were digested using a solution of 10% potassium hydroxide and filtered through a 5 μm pore-size filter. Filters of the samples were observed under a stereomicroscope and the chemical composition of the items detected were analysed by FTIR spectroscopy. A total of 163 items were counted in 37 (92.5%) samples with a mean value of 0.42±0.28 items/g w.w. Fibers were the most detected morphotype and several plastic polymers, such as polypropylene, polyethylene, polyethylene terephthalate and polystyrene, were identified by FT-IR analysis. As store-bought samples, the sources of microplastics could be substantially related to contamination during food processing. However, an intravital exposure to microplastics present in the surroundings waters cannot be ruled out. More foodstuffs need to be investigated for microplastic presence. In this study, microplastic occurrence was reported in freshwater biota intended for human consumption sampled directly from supermarket contributing to the risk assessment of human exposure to microplastics via food consumption.

Changes in Biochemical and Nutritional Qualities of Aerobic and Vacuum-packaged Thua Nao During Shelf-life Storage

Thai traditionally fermented soybean (Thua Nao) has been suggested as a good source of available amino acids and aglycone isoflavones. The objective of this research was to investigate the changes of biochemical and nutritional qualities in aerobic- and vacuum-packed thua Nao during the storage at 4 and 40 degrees C for 60 days. Three Thua Nao samples including Bacillus subtilis TN51-fermented Thua Nao (TNB51), spontaneously fermented Thua Nao (TNMX) and commercial product (MH) were used in this study. It was found that the storage of packed Thua Nao at 4 degrees C could prolong the product shelf-life up to 40 days. The moisture contents, pH values and colour L a* b* of these products were not different in both aerobic and vacuum-packaged products and remained stable throughout the experiment. The Thiobarbituric Acid (TBA) values of all storage Thua Nao were increased during storage; this is in particular for the aerobic packages of the TNMX and TNB51 products, indicating high oxidation of lipids. There was a slight decrease in DPPH radical scavenging effect (18%) and phenolic compounds (6%) of the vacuum-packaged product when stored at 4 degrees C. In contrast, the great losses in total phenolic content (44%), inhibitory activity of DPPH radicals (83%) and total antioxidant (41%) were observed when the products were stored aerobically at 40 degrees C. A reduction in total free amino acids was also found with the highest decrease of Arg in both aerobic- (69%) and vacuum-packages (68%).

川味腊肉货架期中品质变化研究

为了解腊肉货架期中品质的变化以确保其安全性，本文选用产量较大的腊肉为原料，测定并比较了货架期中不同腊肉的感官评分、色泽、质构特性、pH值、水分含量、食盐含量以及微生物指标。结果显示：四种腊肉感官评分、色泽等都随贮藏销售时间的延长而下降，真空包装较散装晾挂的产品更利于保持产品色泽的稳定；pH值和水分含量整体呈下降趋势，而食盐含量逐渐上升；散装晾挂产品的菌落总数呈下降趋势，而真空包装产品略有升高，且在120~150天菌落总数增加明显；四种腊肉制品的大肠菌群值均未超出国家标准，致病菌未检出。产品在货架期总体安全，真空包装较散装晾挂更能保证产品口感和品质，有效延长货架期。 In order to find out the quality changes of bacon during shelf life and ensure their safety, dynamic characteristics of larger-production bacon were investigated and compared by the sensory score, textural properties, pH value, moisture content, salt content and microbiological indicators during the shelf life. The results showed that, the sensory ratings and color indicators all declined with the change of storage and sales time, and the bacon with vacuum packaging were more conducive to maintain the stability of the color of the product than the bulk dry hang one; pH value and moisture content were of the overall downward trend, while the percentage content of the salt is increased gradually; the total number of colonies of bulk hung bacon showed a downward trend, however, vacuum-packed products increased slightly. In the same time, the total number of colonies increased obviously in the 120 days to 150 days. The coliform value of four bacon products did not exceed the national standards, and pathogenic bacteria were not detected. The four products in the shelf life were overall safety. Compared to bulk hung bacon, the vacuum packaging ones were better to ensure the taste and quality, and can extend the shelf life more effectively.

Evaluation of Lactic Acid as an Initial and Secondary Subprimal Intervention for Escherichia coli O157:H7, Non-O157 Shiga Toxin–Producing E. coli, and a Nonpathogenic E. coli Surrogate for E. coli O157:H7

Lactic acid can reduce microbial contamination on beef carcass surfaces when used as a food safety intervention, but effectiveness when applied to the surface of chilled beef subprimal sections is not well documented. Studies characterizing bacterial reduction on subprimals after lactic acid treatment would be useful for validations of hazard analysis critical control point (HACCP) systems. The objective of this study was to validate initial use of lactic acid as a subprimal intervention during beef fabrication followed by a secondary application to vacuum-packaged product that was applied at industry operating parameters. Chilled beef subprimal sections (100 cm(2)) were either left uninoculated or were inoculated with 6 log CFU/cm(2) of a 5-strain mixture of Escherichia coli O157:H7, a 12-strain mixture of non-O157 Shiga toxin-producing E. coli (STEC), or a 5-strain mixture of nonpathogenic (biotype I) E. coli that are considered surrogates for E. coli O157:H7. Uninoculated and inoculated subprimal sections received only an initial or an initial and a second "rework" application of lactic acid in a custombuilt spray cabinet at 1 of 16 application parameters. After the initial spray, total inoculum counts were reduced from 6.0 log CFU/cm(2) to 3.6, 4.4, and 4.4 log CFU/cm(2) for the E. coli surrogates, E. coli O157:H7, and non-O157 STEC inoculation groups, respectively. After the second (rework) application, total inoculum counts were 2.6, 3.2, and 3.6 log CFU/cm(2) for the E. coli surrogates, E. coli O157:H7, and non-O157 STEC inoculation groups, respectively. Both the initial and secondary lactic acid treatments effectively reduced counts of pathogenic and nonpathogenic strains of E. coli and natural microflora on beef subprimals. These data will be useful to the meat industry as part of the HACCP validation process.

Sanitation of Selected Ready-to-Eat Intermediate-Moisture Foods of Animal Origin by E-Beam Irradiation

To optimize the sanitation treatment of ready-to-eat (RTE) intermediate-moisture foods (IMF), the behavior of Listeria monocytogenes Scott A (CIP 103575), L. innocua (NTC 11288), Salmonella enterica serovar Typhimurium (CECT 443), and Escherichia coli O157:H7 (CECT 4972) following treatment with electron-beam irradiation has been studied. As food matrixes, three RTE vacuum-packed products (Iberian dry-cured ham, dry beef [cecina], and smoked tuna) were used. Although an irradiation treatment is not necessary when the 10(2) colony-forming units/g microbiological criterion for L. monocytogenes is applied, a treatment of 1.5 kGy must be applied to IMFs to meet the food safety objective in the case of the "zero tolerance" criterion for the three strains. The IMF products presented negligible modifications of color (L*, a*, and b*), sensory (appearance, odor, and flavor), and rheology (hardness, springiness, adhesiveness, cohesiveness, gumminess, chewiness, and breaking strength) parameters at doses lower than 2 kGy. Therefore, the treatment of 1.5 kGy warrants safe IMF with sensory properties similar to those of the genuine products.

Quality of meat products packaged and stored under vacuum and modified atmosphere conditions.

The experimental materials comprised cooked coarsely-ground and finely-ground sausages. The sausages were packaged in vacuum (V) and in modified atmospheres with the following composition: 20% CO2, 80% N2 (A1); 50% CO2, 50% N2 (A2); 80% CO2, 20% N2 (A3). The samples were stored at around 4°C for 15days. The measurements were repeated 8 times: at the completion of the production process and at 3-day intervals (day 0, 3, 6, 9, 12, 15) during storage. Drip loss changes in the package were analyzed during storage. Meat products were subjected to a sensory evaluation. The obtained results show that changes in the quality of meat products packaged under modified atmosphere are significantly influenced by the composition of the applied atmosphere. A wider range of quality changes were noted in vacuum-packaged products. Changes in the quality of modified atmosphere packaged products were less significant.

Chemical and Sensory Parameters of Heat-treated Vacuum-packaged Broiler and Hen Fillet Products

Chemical and Sensory Parameters of Heat-treated Vacuum-packaged Broiler and Hen Fillet Products The heat treatment of vacuum-packaged products - Sous vide processing method - that offers convenience and storage stability, combined with poultry meat marinating was used in the current study. The aim of this research was to evaluate the effect of a fruit-vegetable additive on chemical and sensory parameters of heat-treated vacuum-packaged poultry meat products made from broiler or hen fillets. The skinless fillets and other ingredients were packaged in polyamide/polyethylene (PA/PE) pouches, vacuum sealed, marinated, heat treated, and chilled rapidly. The following parameters were evaluated: moisture content (LVS ISO 1442:197), protein content (LVS ISO 937:1978), fat content (LVS ISO 1443:1973), ash content (ISO 936:996), degree of liking, and intensity of sensory properties (ISO 4121: 2003). The smallest changes in moisture content among the studied samples were observed in those prepared with the fruit-vegetable additive if compared to a raw fillet. In the process of heat treatment, the protein content in dry matter of broiler and hen fillet decreased (p<0.05), whereas fat content decreased in broiler fillet but increased in hen fillet (p<0.05). Sensory evaluation results showed that panellists preferred broiler fillet (6.6) and hen fillet (5.8) products which were prepared without the fruit-vegetable additive. Evaluation of the intensity of sensory properties showed that there do not exist significant differences in aroma, colour, flavour, and aftertaste of heat-treated vacuum-packaged hen and broiler fillet (p>0.05), but texture of broiler fillet products is more tender than texture of samples made from hen fillet.

Effects of Storage Conditions on the Shelf Life of Liquid-Smoked Tilapia (<i>Oreochromis niloticus</i>) Fillets

In this study, the pH, total volatile base nitrogen (TVB-N) amounts, total viable counts (TVC) of microbial flora, and the sensory quality of liquid-smoked tilapia fillets were analyzed under different storage conditions. Lengthy storage caused, the smoked flavor to disappear and juice seeped from the samples. Over time, it was found that the pH of the products decreased and then subsequently increased, whilst the amount of TVB-N showed an overall increasing trend. Under all storage conditions tested, the TVC of microbial flora slowly increased, followed by a sharp increase, and then stabilized. These results showed that vacuum-packed products stored at low temperatures were highly stable; hence this storage method can effectively guarantee the quality of liquid-smoked tilapia fillets and the extension of the shelf life.

Controlling the Bleeding of Carmine Colorant in Crabstick

Carmine used to color surimi seafood often seeps or bleeds from red-colored meat to white meat when vacuum-packed products go through high-temperature long-time pasteurization. Various physical and chemical treatments were examined to investigate means to inhibit or minimize carmine bleeding in surimi seafood products. Degree of bleeding was analyzed using L* (lightness) and a* (redness) as affected by carmine concentrations, pH, pasteurization conditions, and added calcium compounds. Bleeding was significantly affected by carmine concentrations. Optimum carmine concentration in color paste was 0.1%. Bleeding increased when pasteurization time and/or temperature increased. Color bleeding was also affected by moisture content of surimi paste. Carmine bleeding was minimized as pH of color solution decreased. The degree of bleeding was controlled as calcium compounds were added in color solution in a descending order of calcium chloride, calcium acetate, and calcium hydroxide. Minimal inhibition was obtained when color solutions contained calcium citrate, tricalcium phosphate, and calcium lactate. Practical Application: This manuscript addresses one of the long time problems in the surimi crabstick industry. Various means to control carmine bleeding or color transfer under high temperature for long time pasteurization were demonstrated. However, further study must continue to stop bleeding completely.

Survival of Staphylococcus aureus and Listeria monocytogenes on Vacuum-Packaged Beef Jerky and Related Products Stored at 21°C

In the manufacture of beef jerky, a thermal lethality step is followed by drying to prevent growth of pathogenic bacterial postprocessing contaminants on the finished product. Recent guidelines from the U.S. Department of Agriculture have raised the question of the maximum water activity (aw) in jerky products that will inhibit growth of pathogenic bacteria. The survival of the potential postprocessing contaminants Staphylococcus aureus and Listeria monocytogenes was evaluated on 15 vacuum-packaged beef jerky and related products with aw values ranging from 0.47 to 0.87, just below the 0.88 limit reported for anaerobic growth of S. aureus. Small individual product pieces were inoculated on the outer surface with five strains each of S. aureus and L. monocytogenes, repackaged under vacuum, and stored at room temperature (21°C) for 4 weeks. Pathogen numbers were determined before storage and after 1 and 4 weeks. None of the 15 jerky products supported growth of either pathogen. Counts of S. aureus fell by 0.2 to 1.8 log CFU after 1 week of storage and by 0.6 to 5.3 log CFU after 4 weeks of storage. Numbers of L. monocytogenes fell by 0.6 to 4.7 log CFU and by 2.3 to 5.6 log CFU after 1 and 4 weeks of storage, respectively. Although factors other than aw may have some effect on pathogen survival, the results of the present study clearly support drying beef jerky to an aw of ≤0.87 to ensure that bacterial pathogens cannot grow on vacuum-packaged product stored at room temperature.

Analysis of Carbon Monoxide in Commercially Treated Tuna (Thunnus spp.) and Mahi-Mahi (Coryphaena hippurus) by Gas Chromatography/Mass Spectrometry

A simple and confirmative method for quantitative determination of carbon monoxide in tuna and mahi-mahi tissues using GC/MS, following chemical liberation of CO into headspace, is described. Carbon monoxide in recent years has been employed by the fishery industry to preserve fresh appearance in selected species of finfish during frozen storage, particularly in vacuum-packaged products. Indigenous CO contents of fresh Ahi tuna and mahi-mahi were examined using the method described in this study and found to be close to or less than 150 and 100 ng/g, respectively. Commercially CO-treated, vacuum-packaged tuna from multiple sources consistently showed CO level near or greater than 1 mug/g, while CO level in the only CO-treated frozen mahi-mahi sample was in the 500 ng/g range. The difference between untreated and treated specimens was in the range of 1 order of magnitude and thus suggested an easy quantitative and confirmative method of CO using widely available instrumentation that may be potentially useful for regulatory purpose in determining whether a commercially available product has been exposed to CO even if not labeled as such.

Microbial profiles of commercial, vacuum-packaged, fresh pork of normal or short storage life

The microbial ecology of fresh vacuum-packed pork cuts during storage at −1.5 °C for up to 45 days was examined to characterize rates of microbial growth and pH changes in commercially prepared products of normal storage quality. Pork loins in commercial distribution with odour defects were also studied to determine a possible cause of the defects and avoid future problems. In addition, microbial profiles of pork cuts from two plants were compared, after storage for 25 days at −1.5 °C, to identify possible reasons for differences in the storage life of product from the plants. The effects of a change in sanitation procedures on the microbial populations of products stored for 25 days were also studied. With normal product, microbial growth in different packages progressed at different rates, reflecting differences in initial levels of bacterial contamination. All samples in the study reached 8 weeks without apparent organoleptic change and samples carried 5.8±1.2 log bacteria cm −2 (mean±S.D.). The flora of loins with the odour defect were predominately lactic acid bacteria (LAB) and carnobacteria, but they contained large fractions of Enterobacteriaceae <35 days after packaging. Aeromonas spp. and Shewanella spp. were likely responsible for the sulfide-putrid smell of these spoiled products, but species of Enterobacteriaceae and lactic acid bacteria could have contributed to spoilage. Comparison of microbial groups present in 16 other cuts, half from each of two commercial plants, which were stored for 25 days at −1.5 °C, showed that larger fractions of Enterobacteriaceae were present in samples from the plant having difficulty achieving the desired storage life. Additional bacterial samples from 12 cuts supplied by the latter plant obtained after adoption of an acid sanitizer step in the plant cleaning regimen, and also stored for 25 days at −1.5 °C, yielded few Enterobacteriaceae, Aeromonas or Shewanella. Use of an acid sanitizer in plant cleaning may be a means of controlling alkali-tolerant bacteria such as Aeromonas or Shewanella which can contaminate pork cuts and spoil vacuum-packaged product. The fraction of Enterobacteriaceae in bacteria populations on fresh pork stored for 25 days at −1.5 °C may be a useful indicator of the effectiveness of plant sanitation.

Characterisation of a lard cured with spices and aromatic herbs

The study considered the proximate composition, pH, free acidity, MDA and peroxide values of a cured and ripened lard covered with spices and aromatic herbs, these latter parameters, due to lipolytic endoenzymatic phenomena, tended to increase until the end of the salting period. Throughout the production phases the bacterial load was very low. The final vacuum-packed product had a shelf-life of about 90 days and its fatty acid and cholesterol composition was typical of lard. A GC/MS study of the spices/herbs in the lard highlighted which components came from the spices/aromatic herbs and which came from phenomena due to lipolytic endoenzymatic processes.

Antimicrobial Activity of Foodborne Paenibacillus and Bacillus spp. against Clostridium botulinum

The saprophytic Paenibacillus and Bacillus spp. found in cooked chilled foods may have an effect on the growth of Clostridium botulinum, a major microbiologicalhazard, especially for pasteurized vacuum-packaged products. Culture supernatants of 200 strains of Paenibacillus and Bacillus strains isolated from commercial cooked chilled foods containing vegetables were screened for activity against C. botulinum type A, proteolytic type B, and type E strains in a well diffusion assay. Nineteen strains were positive against C. botulinum. Among those, seven Paenibacillus polymyxa strains showed the highest antibotulinal activity and the largest antimicrobial spectrum against C. botulinum strains. The antibotulinal activity was evaluated throughout the growth of a representative strain of the positive P. polymyxa strains. The antimicrobial activity was detected in the culture supernatant from late-log/early stationary phase of the bacteria, which occurred after 7 to 10 days of incubation at 10°C and after 2 to 3 days at 20°C in nutrient broth and in vegetable purées under aerobic or anaerobic conditions. In co-cultures with the positive strain of P. polymyxa in nutrient broth and vegetable purées, a C. botulinum type E strain was inhibited whenever P. polymyxa reached stationary phase and produced its antimicrobial activity before C. botulinum began its exponential growth phase. The antimicrobial activity of P. polymyxa against C. botulinum was attributed to the production of antimicrobial peptides resistant to high temperature and acidity. Other gram-positive and -negative bacteria (Escherichia coli, Streptococcus mutans, Leuconostoc mesenteroides, and Bacillus subtilis) were also sensitive to these antimicrobial peptides.