Cooked Ham Research Articles

Training in quantitative microbial risk assessment of Listeria monocytogenes in processing chains: Quantification of biofilm-cells transfer integrating virulence and persistence factors.

Food safety is a global challenge, with nearly 1 in 10 people worldwide falling ill each year from consuming contaminated food. The risk is particularly high in ready-to-eat (RTE) products, which are consumed without further cooking to eliminate harmful microorganisms. To address this, the University of Cordoba and the University of Bologna, in the framework of the EU-FORA programme, developed a training programme focused on quantitative microbial risk assessment (QMRA) for Listeria monocytogenes in RTE food processing chains, a significant public health concern due to its association with severe foodborne illnesses. The programme aimed to train the fellow in advanced food microbiology techniques, predictive modelling and comprehensive QMRA methodologies. The fellow gained hands-on experience with predictive microbiology models applied to real-world scenarios, particularly RTE meat and fish products. Activities included developing predictive models for microbial growth and conducting challenge tests to evaluate Listeria behaviour in various foods. Emphasising data collection and statistical analysis, the fellowship explores the dynamics of Listeria within the food supply chain. A case study on sliced cooked ham demonstrates QMRA's application, using Monte Carlo simulations to estimate Listeria concentrations at consumption, ultimately informing risk management strategies. This initiative aimed to increase the number of food safety risk assessment experts in Europe, thereby enhancing public health outcomes related to foodborne diseases.

Sensory profile and color and oxidative stabilities of sliced restructured cooked hams with added S-nitroso-N-acetylcysteine as a nitrite replacement

The objective of this study was to evaluate the effects of replacing sodium nitrite by S-nitroso-N-acetylcysteine (NAC-SNO) at different addition levels (50, 150, and 300 mg of equivalent nitrite–Neq/kg) on the sensory profile and on the quality characteristics of restructured cooked hams during sliced storage (up to 60 days at 4°C). The addition of NAC-SNO did not affect (P > 0.05) the pH of the products and resulted in lower (P < 0.05) residual nitrite content (1.79 ± 0.61 mg/kg) and higher (P < 0.05) TBARS values (0.86 ± 0.44 mg MAD/kg) than nitrite added samples (8.43 ± 2.37 mg/kg and 0.66 ± 0.25 mg MAD/kg, respectively). During storage, an increasing trend in lipid oxidation was observed regardless of the curing agent used. The addition of 50 mg NEq/kg of NAC-SNO resulted in products with a more yellowish color tone (higher h values) and less intensity (lower C* values) than all the other products. The equimolar addition of 150 mg NEq/kg of NAC-SNO resulted in a similar pink color acceptance to nitrite; however, they were characterized by a higher (P < 0.05) characteristic flavor and aroma intensity and obtained greater (P < 0.05) sensory acceptance than nitrite. The addition of 150 mg NEq/kg of NAC-SNO was suggested as a substitute for nitrite to achieve the desired stability and sensory characteristics of cooked cured products.

Enhancing High-Pressure Bacterial Inactivation by Modified Atmosphere Packaging: Effect of Exposure Time and Cooked Ham Formulation

AbstractHigh-pressure processing (HPP) is a non-thermal preservation technology that can be applied as a control measure to inactivate pathogens and spoilage microorganisms once RTE meat products are packaged in a convenient format. HPP efficacy highly depends on product characteristics, but the impact of the sodium-reduced formulations and the effect of packaging atmosphere are scarcely known. The aim of the present work was to assess the effect of standard and sodium-reduced formulations from two different brands (A, B) under different packaging (vacuum and modified atmosphere packaging (MAP)) on the HPP inactivation kinetics of Listeria monocytogenes and spoilage lactic acid bacteria in cooked ham. Slices of cooked ham with standard and sodium-reduced formulations were inoculated with L. monocytogenes CTC1034 and Latilactobacillus sakei CTC746 (slime producer), packaged in vacuum and MAP (CO2:N2, 20:80), and pressurized (400 MPa/0–15 min) after 1 h (vacuum, MAP) or 24 h (MAP-exposed). Parameters of HPP inactivation kinetics were estimated by fitting the Weibull model to log reduction data. Results showed that the efficacy of HPP in sodium-reduced cooked hams tended to decrease compared to standard formulations, being the difference statistically significant for L. sakei. For L. monocytogenes, a significant enhancing effect of MAP was observed when HPP was applied just after packaging (1 h, MAP) of cooked ham of brand A. In the case of L. sakei, the inactivation by HPP was only enhanced in MAP-exposed samples. Therefore, the use of HPP as a control measure must be applied through a product-oriented approach considering the type of packaging and the time period between packaging and HPP.

Impact of a Biopreservative Derived from Lactic Fermentation on Quality after Food Processing: A Case Study on Sliced Cooked Ham

Impact of a Biopreservative Derived from Lactic Fermentation on Quality after Food Processing: A Case Study on Sliced Cooked Ham

Hybrid Nanoclay/Clove Essential Oil in Cellulose Acetate Bionanocomposites for Cooked Ham Active Packaging

Hybrid Nanoclay/Clove Essential Oil in Cellulose Acetate Bionanocomposites for Cooked Ham Active Packaging

Evaluation biodegradable films with green tea extract for interleafing sliced meat products

A selection of formulations with different polymers and concentrations of green tea extract was conducted for application as interleafs in sliced meat products. Films were formulated using cellulose acetate, corn starch, and chitosan with the addition of 1.0, 2.5, and 5.0% green tea extract. Higher antioxidant activity was observed with the 1.0% concentration of green tea extract (P < 0.05), regardless of the formulation, with continuous release of the extract for up to 60 days and average IC50 of 0.09 and 0.31 mg/mL for the corn starch and chitosan active films, respectively. Interleafing the sliced ham resulted in lower lipid oxidation after 60 days of storage (P < 0.05). Starch-based films with green tea extract were effective, significantly reducing lipid oxidation in sliced and interleafed cooked ham, suggesting their potential to extend the shelf life of these refrigerated products.

Clean labelling sodium nitrite at pilot scale: In-situ reduction of nitrate from plant sources and its effects on the overall quality and safety of restructured cooked ham

Growing health and environmental concerns have increased demand for all-natural products, with a focus on clean labelling. Sodium nitrite is the most widely used additive in the meat industry because it imparts the typical cured flavour and colour to meat products and, most importantly, their microbiological safety. However, due to health concerns, the European Commission is proposing revised regulations to reduce nitrate and nitrite levels in meat products. As a result, the meat industry is actively seeking alternatives. This study explored the production of four cooked hams utilising nitrate-rich vegetable sources combined with two different nitrate-reducing commercial food cultures, alongside a control ham prepared with sodium nitrite (150 ppm). Microbiological, physico-chemical (pH, water activity, nitrate and nitrite concentration, lipid profile, lipid oxidation) and sensory (texture and colour profile) characterisation of the products was carried out. Challenge tests for Listeria monocytogenes, Clostridium sporogenes and Clostridium perfringens have been performed to assess the growth of pathogens, if present in the products. Results revealed comparable microbiological and physico-chemical profiles across ham formulations, with minor differences observed in colour parameters for sample C. The sensory analysis showed that for the pilot ham formulations A and D, there were no significant differences in consumer perception compared to the control ham. In the challenge tests, L. monocytogenes levels were similar in both control and tested hams. There were no significant differences in C. sporogenes and C. perfringens counts at any temperature or between test and control samples. These results indicate that this technology has a potential future in the cured meat sector, as regulators mandate the reduction of added synthetic chemicals and consumers seek healthier and more natural ingredients in their daily diets.

Sensory characterisation of meatless and nitrite-free cooked ham alternatives in comparison to conventional counterparts: Temporal dominance of sensations and partial napping with ultra-flash profiling

The cooked ham market is expanding with nitrite-free and meatless alternatives gaining traction as leading trends. An understanding of the attributes that influence the sensory quality of cooked ham is crucial for developing healthier and environmentally sustainable products. The primary aim of this study was to investigate how the removal of nitrites and the use of meatless ingredients affect the sensory characteristics of cooked ham currently available in the Irish market. Sensory evaluation of selected cooked hams (n = 8), including alternatives without nitrites or based on mycoprotein (meatless), was conducted using Temporal Dominance of Sensations (TDS) for in mouth processing and Partial Napping (PN) with Ultra-Flash Profiling (UFP) for the appearance, by a trained sensory panel (n = 9). The nitrite-free cooked ham displayed a similar temporal sensory profile and appearance to the products of the same category, highlighting the opportunity for more nitrite-free products to enter the market. The meatless product was dominated by a “smoky” flavour, which was perceived as “artificial”. Meatless ham had a more distinct appearance than the meat-based products and was associated with attributes such as “fake”, “artificial colour” and “unappealing”. In general, results revealed distinct differences between whole-muscle and sectioned and formed cooked ham products in terms of texture, flavour, and appearance. PN and UFP grouped whole-muscle cooked hams together, which were associated with terms “natural-looking”, “better quality” and “healthier”, while sectioned and formed cooked hams were perceived as “cheap” and “artificial”. The results of this study contribute to a better understanding of the sensory attributes of cooked ham products emphasising the challenges related to novel formulations, and offers valuable insights for the development of healthier and more sustainable meat products within the food industry.

Exploring Propolis as a Sustainable Bio-Preservative Agent to Control Foodborne Pathogens in Vacuum-Packed Cooked Ham.

The search for natural food additives makes propolis an exciting alternative due to its known antimicrobial activity. This work aims to investigate propolis' behavior as a nitrite substitute ingredient in cooked ham (a ready-to-eat product) when confronted with pathogenic microorganisms of food interest. The microbial evolution of Listeria monocytogenes, Staphylococcus aureus, Bacillus cereus, and Clostridium sporogenes inoculated at known doses was examined in different batches of cooked ham. The design of a challenge test according to their shelf life (45 days), pH values, and water activity allowed the determination of the mesophilic aerobic flora, psychotropic, and acid lactic bacteria viability. The test was completed with an organoleptic analysis of the samples, considering possible alterations in color and texture. The cooked ham formulation containing propolis instead of nitrites limited the potential growth (δ < 0.5 log10) of all the inoculated microorganisms until day 45, except for L. monocytogenes, which in turn exhibited a bacteriostatic effect between day 7 and 30 of the storage time. The sensory analysis revealed the consumer's acceptance of cooked ham batches including propolis as a natural additive. These findings suggest the functionality of propolis as a promising alternative to artificial preservatives for ensuring food safety and reducing the proliferation risk of foodborne pathogens in ready-to-eat products.

Determination of Nisin Concentration to Control Listeria monocytogenes in Cooked Ham.

Listeria monocytogenes contamination may occur after thermal processing of cooked ham. This study aimed to determine the effective nisin concentration to inhibit the growth of L. monocytogenes. Two batches of ham were prepared by adding 12.5mg nisin/kg ham at brine injection (assay 1) or tumbling stage (assay 2). Another piece of cooked ham was prepared by adding 32mg nisin/kg ham at brine injection (assay 3). Afterward, samples of cooked ham were contaminated with L. monocytogenes cocktail (4 log CFU/mL). The results of assays 1 and 2 revealed that this nisin concentration was ineffective in inhibiting L. monocytogenes in ham. The minimum bactericidal concentration test results indicated that each L. monocytogenes strain had a different sensitivity profile and the cocktail had greater resistance. High concentrations of nisin (32mg/mL) were efficient in controlling the most resistant strains. Statistical analyses were performed using ANOVA and Tukey's test. This higher nisin concentration was effective in controlling the L. monocytogenes cocktail in cooked ham over 10days. The findings highlight the potential of high nisin concentrations to effectively reduce L. monocytogenes contamination in cooked ham.

The pigment transformation from nitrosylheme to Zn-protoporphyrin IX in cooked ham products

In this study, we investigated cooked hams to understand the relationship between display life and quality changes, as well as the microbiological characteristics of refrigerated storage for up to 90 days. Initially, the L* and a* values exhibited an initial decline with a gradual restitution to levels insignificantly disparate from those Day 15 hams. In contrast, the b* and h° values demonstrated an ascending pattern, indicating an augmentation in yellow intensity during the storage. Furthermore, there was an observable escalation in the C* value following 45 days of storage, implying an amplified luminosity and vividness of color during the latter phase of the storage period. Analyses of TBARS, TVB-N, and other physicochemical indexes indicated that the hams underwent deterioration during storage. Whereas, UV–vis and fluorescence spectroscopy illustrated that the pigment in cooked hams changed from nitrosylheme (NO-heme) to Zn-protoporphyrin IX (ZnPP) during storage. The NO-heme content decreased from 41.08 ± 0.44 to 12.76 ± 0.29 mg/kg, while the ZnPP content increased from 12.19 ± 0.41 to 89.44 ± 1.57 mg/kg. The structure of the bacterial community in the ham samples changed over the storage period. Towards the end of the shelf life, the microbial population was dominated by Lactic acid bacteria (LAB), particularly Latilactobacillus (34.91%) and Leuconostoc (19.73%). Redundancy analysis and Pearson correlation revealed a positive correlation between Latilactobacillus and Leuconostoc with TBARS, TVB-N, ZnPP content, and negative correlations with Aw and NO-heme.

The relationship between biogenic amines and the growth of spoilage related microorganisms in sliced cooked ham stored under different packaging

The relationship between biogenic amines and the growth of spoilage related microorganisms in sliced cooked ham stored under different packaging

S-nitrosothiols as nitrite alternatives: Effects on residual nitrite, lipid oxidation, volatile profile, and cured color of restructured cooked ham

This study evaluated the use of the S-nitrosothiols, S-nitroso-N-acetylcysteine (NAC-SNO) and S-nitroso-N-acetylcysteine ethyl ester (NACET-SNO), at different concentrations (25–300 mg nitrite equivalent – NEq/kg) as sodium nitrite substitutes in restructured cooked hams. The pH value and instrumental cured color were not affected by the type or amount of curing agent used. Products with 25 and 50 mg/kg ingoing nitrite had lower thiobarbituric acid-reactive substance values than those with equimolar amounts of S-nitrosothiols. Products with >150 mg NEq/kg of S-nitrosothiols had residual nitrite similar to 50 mg/kg nitrite, and this resulted in the same volatile compound profile as nitrite added in equimolar amounts. A 300 mg NEq/kg of S-nitrosothiols was required to obtain a similar and minimally stable cured pink color perception as sliced samples with 50–150 mg/kg added nitrite. The results obtained reinforce the great potential of both alternative curing agents in the complete replacement of nitrite by equimolar amounts in restructured cooked products; however, differences in cured color stability should be considered.

Incorporation of garlic (Allium sativum) essential oil into cellulose acetate films: effect on the preservation of sliced cooked ham

AbstractGarlic essential oil (GEO) has been recognized as a natural antimicrobial agent with a broad spectrum of action that can be associated with polymeric sustainable matrices to provide active packaging capable of improving the preservation of ready‐to‐eat meat products. In this sense, the present study aimed to evaluate the effect of cellulose acetate (CA) films incorporated with GEO on the growth of spoilage microbial groups (psychrotrophic (PSY) and lactic acid bacteria (LAB)) and physicochemical characteristics (pH, acidity index, color and index of thiobarbituric acid) of vacuum‐packed cooked sliced ham. Four treatments were evaluated (no film, CA‐film without GEO, CA‐film with 1.5% of GEO and CA‐film with 3% of GEO, applied as interfold packaging) over time (12 days). There was a significant reduction (ca 2.0 log cycle) in PSY and LAB growth when the active films were applied between the ham slices. Also, the lag phase of PSY was extended from around 2 to 6 days, which might positively impact the product's shelf life. However, the active films showed no significant effect on the food physicochemical characteristics. Therefore, the active CA‐films incorporated with small amounts of GEO could be an interesting alternative to reduce the impact of microbial spoilage on sliced cooked ham. © 2023 Society of Industrial Chemistry.

Technical Feasibility Study for Development of Reference Material for Nitrate in Meat Product

Nitrate measurement is a fundamental part of quality control in the meat products industries. Ensuring the technical validity of the results of these measurements can be achieved through the adoption of appropriate metrological tools such as reference materials. The technical feasibility for producing a nitrate reference material in a meat product was evaluated by preparing a batch of material on a small scale. The adequacy of the preparation procedure was evaluated by means of pertinent physicochemical and microbiological measurements. A batch of 175 units containing approximately 5 g of lyophilized cooked ham in each package was produced. The batch was submitted to preliminary studies to assess homogeneity and stability under transport conditions, in accordance with ISO 17034 and the applicable ISO guides.

Control of the Growth of Listeria monocytogenes in Cooked Ham through Combinations of Natural Ingredients.

In the ready-to-eat food industry, Listeria control is mandatory to ensure the food safety of the products since its presence could cause a disease called listeriosis. The objective of the present study was to carry out a challenge test to verify the efficiency of different combinations of natural antimicrobial ingredients against Listeria monocytogenes to be used in ready-to-eat foods. Six different formulations of cooked ham were prepared: a control formulation and five different formulations. An initial inoculation of 2 log cycles was used in the different products, and the growth of Listeria was monitored at different temperatures and times (4 °C for 17 w and 7 °C for 12 w). Control samples showed a progressive growth, reaching 5-6 log after 3 or 4 weeks. The rest of the samples showed constant counts of Listeria during the entire study. Only samples containing 100 ppm nitrite + 250 PPM ascorbic acid + 0.7% PRS-DV-5 did not control the growth of Listeria at 7 °C after 7 w of storage. The results obtained allowed us to classify the cooked ham prepared using natural ingredient combinations as a "Ready-to-eat food unable to support the growth of L. monocytogenes other than those intended for infants and for special medical purposes".

Carvacrol release kinetics from cellulose acetate films and its antibacterial effect on the shelf life of cooked ham

Antibacterial films of the cellulose acetate (CA) and carvacrol were investigated regarding the migration to fat-like food simulants and the impact on the shelf life of the sliced cooked ham vacuum. Mathematical models described the bacterial growth in ham and the carvacrol release kinetics. The carvacrol antimicrobial activity against two food-borne spoilage bacteria was demonstrated. Carvacrol showed minimum inhibitory concentration (MIC) values of 293 and 194 μg/mL for Weisella viridescens and Pseudomonas fluorescens, respectively, and minimum bactericidal concentration (MBC) values of 488 μg/mL for both bacteria. The active CA-films with 5 and 10% carvacrol were used for bacterial inhibition and shelf life extension on the ham. Applying CA-film with 10% carvacrol decreased the growth rate and the final maximum population, increasing the latency phase of W. viridescens. It increased the ham shelf life by 10 days. The carvacrol migration demonstrated that obtaining films with long-acting and slow release to a food matrix is possible. In food fluids simulations, the migration was faster, with diffusion coefficients between 10−13 and 10−15 m2/s. The results demonstrate the CA-film with carvacrol as a potential active packaging to increase the shelf life of complex food matrix.

The Antibacterial Effect of the Films Coated with the Layers Based on Uncaria tomentosa and Formitopsis betulina Extracts and ZnO Nanoparticles and Their Influence on the Secondary Shelf-Life of Sliced Cooked Ham

Microbial surface contamination of the cooked ham sliced by shop assistants has an influence on its potential secondary shelf-life. Active packaging may be the solution. The first goal of the work was to obtain coatings based on Formitopsis betulina and Uncaria tomentosa extracts (separately), with the addition of nanoparticles of ZnO (as a synergetic agent to increase plant extracts’ antimicrobial effectiveness), that could be active against selected bacterial strains. Another aim of the work was to determine the influence of obtained active layers on microbial purity and texture of the samples. The results of the study demonstrated that the layers containing F. betulina or U. tomentosa extracts with the addition of ZnO nanoparticles inhibited Staphylococcus aureus, Bacillus atrophaeus, and Escherichia coli growth completely and decreased the number of Pseudomonas syringae cells. Analyzing microbial purity of sliced cooked ham portions after storage, it was observed that the active packaging based on U. tomentosa extracts had a greater influence on the total count than the coatings containing F. betulina extracts and that both active packaging materials affected the microbial purity of the cooked ham. Analyzing the textural parameter changes after 48 h of storage, a decrease in the gumminess, chewiness and cohesiveness values was noted, but only for the ham portions stored in bags covered with the coating based on U. tomentosa. The effectiveness of the active packaging on textural parameters after 96 h of storage was not noticed.

Selection of food cultures with protective properties for cooked ham.

Sliced cooked ham stored in modified atmosphere packaging (MAP) can be spoiled by lactic acid bacteria (LAB) which are dominating under psychrotrophic conditions. Depending on the strains, the colonization can result in a premature spoilage characterized by off-flavors, gas and slime production, discoloration, and acidification. The purpose of this study was the isolation, identification and characterization of potential food culture with protective properties, able to prevent or delay spoilage in cooked-ham. The first step was to identify by means of microbiological analysis, the microbial consortia both in unspoiled and in spoiled lots of sliced cooked ham by the use of media for the detection lactic acid bacteria and total viable count. Counts ranged from values lower than 1 Log CFU/g to 9 Log CFU/g in spoiled and unflawed samples. The interaction between consortia was then studied in order to screen for strains able to inhibit spoilage consortia. Strains showing antimicrobial activity were identified and characterized by molecular methods and tested for their physiological features. Among a total of 140 strains isolated, nine were selected for their ability to inhibit a large number of spoilage consortia, to grow and ferment at 4°C and to produce bacteriocins. The effectiveness of the fermentation made by food culture was evaluated, through challenge tests in situ, analysing the microbial profiles of artificially inoculated cooked-ham slices during storage by high throughput 16S rRNA gene sequencing. The native population in situ resulted competitive against the inoculated strains and only one strain was able to significantly reduce the native populations reaching about 46.7% of the relative abundance. The results obtained in this study provide information about the selection of autochthonous LAB on the base of their action against spoilage consortia, in order to select protective potential cultures able to improve the microbial quality of sliced cooked ham.

Evaluation of the antimicrobial activity of sodium alginate films integrated with cinnamon essential oil and citric acid on sliced cooked ham

AbstractBio‐based antimicrobial films have been developed using sodium alginate and 6 wt% of cinnamon essential oil (CEO) as a volatile antimicrobial substance and 4 and 6 wt% of citric acid (CA) as a non‐volatile antimicrobial substance. Antimicrobial activity of the films was tested in in vitro tests against Escherichia coli and Listeria innocua by disc diffusion or vapour diffusion assay. Sodium alginate films containing CA exhibited a zone of inhibition between 30.86 ± 2.55 and 45.87 ± 1.90 against E. coli and L. innocua in the disc diffusion assays. Films containing CEO also showed significant antimicrobial activities in the vapour diffusion assays that resulted in a log reduction of 5.3 for E. coli and 3.2 for L. innocua after 6 days. Antimicrobial activities of all films were also tested against L. innocua on sliced cooked ham. Films containing CEO did not prevent the growth of L. innocua inoculated on ham. On the other hand, sodium alginate films with CA fully inhibited the growth of L. innocua on ham during storage at 7.5°C for 12 days resulting in a bacterial count below the detection limit after 12 days. The addition of antimicrobial substances in sodium alginate films resulted in a slight colour change (but significant) and reduced the tensile strength of the films significantly. Adding CA to sodium alginate films increased the moisture content (from 24.81% to 35.41–48.02%) as well as the elongation at break (from 11.3% to 22.6–33.2%) of the films.