Cold Chain Break Research Articles

Development of an exposure assessment industrial model for Bacillus cereus in rice matrix containing insect chitosan.

An exposure assessment model for industrial use has been developed by using kinetic data from inactivation and growth of Bacillus cereus spores. It can provide a valuable tool for estimating the concentration of B. cereus after a storage period of 24 h at a specified temperature (20 °C) and for an estimation of the percentage of contaminated portions according to the input data of the model. This model considers a rice-derived product that has undergone a standard cooking process at 95 °C for 20 min. According to the results, the presence of chitosan affects the final microbial load after storage, potentially serving as an additional control measure in the event of cold chain abuse or break. Chitosan's antimicrobial properties likely play a role in reducing microbial growth during storage, thereby contributing to enhanced food safety. In practical terms, this suggests that incorporating chitosan into food products, especially those susceptible to microbial contamination like rice derivatives, could help mitigate risks associated with temperature abuse or cold chain disruptions. By acting as a protective barrier against microbial proliferation, chitosan offers a preventive measure to maintain product quality and safety throughout the supply chain. Considering two scenarios, 104 or 107 as initial contamination the model estimated that the 55 and 100% of portions would be respectively contaminated, according to a Performance Criteria of 4 log reductions.

Low-cost multispectral sensor reveals cold chain breaks, meat type, and storage time in chicken meat samples

A portable and low-cost spectrometric system has been proposed to discriminate cold chain (frozen) interruption during the supply chain, as well as, the sample type among four different tested chicken meat and products (nugget, wing, thigh and drumstick) and the storage time elapsed after the cold chain break. To achieve this, an AS7265x sensor chipset was used and controlled by a custom programmed microcontroller through a Qwiic I2C interface. Communication between the user and the sensor setup was made using a custom programmed interface developed using the Python. Frozen chicken samples were thawed under various temperature-time combinations (4, 8, 16, and 24 h at 4 and 24 °C) and then refrozen at -18 °C. The refrozen samples were stored for up to 60 days. Spectral measurements (410–940 nm) were taken before thawing and at 1, 10, 30 and 60 days of storage after refreezing. The spectra obtained were analysed using Principal Component Analysis and outliers were eliminated using Mahalobobis distance. Several classification models (including Decision Tree, Random Forest, AdaBoost, Support Vector Machine, k-Nearest Neighbors, Gaussian-Naïve Bayes, Multilayer Perceptron, Gaussian Process, Linear and Quadratic Discriminant Analysis and Partial Least Squares Discriminant Analysis) were trained where appropriate. The top models with the highest predictive ability were selected and merged to build Soft Voting Classifiers (SVC) for each feature to be predicted. The SVC models correctly classified the samples with 93%, 92% and 83% accuracy for cold chain interruption, chicken meat/product type and storage time after thaw-refreeze cycle, respectively. In addition, a graphical interface was also developed so that it can be used by end users for food safety concerns. The results showed the potential of the developed low-cost sensor to rapidly detect the potential food safety risks due to cold chain breakage and to trace back the problem by predicting the storage time after refreezing.

Synergistic effect of red-white LED and modified atmosphere packaging on okra quality maintenance and its mechanism in simulated cold chain logistics

Okra is rich in nutritional value, but transportation vibration, cold chain breakage and improper storage can quickly accelerate quality deterioration. In this study, we simulated the cold chain transportation process to find the synergistic effect of red-white LED illumination combined with modified atmosphere packaging (MAP) on okra quality maintenance and its mechanism of action. After 16 d of storage, LED+MAP can better avoid water loss and wilting in okra. The fracturability was 35 %, 33 %, and 40 % of fresh okra for LED, MAP, and LED+MAP, respectively, compared to 17 % for CK. CK produced unpleasant odors, but the odor of LED+MAP was close to the fresh. LED+MAP maintained the stability of the nutrient content of okra. The chlorophyll content of LED+MAP was reduced to 64 % of the original compared to 35 % of that for CK. The total phenol content of LED+MAP was reduced to 55 % of the original compared to 26 % of that for CK. The total flavonoid content of LED+MAP was reduced to 72 % of the original compared to 56 % of that for CK. LED+MAP regulated the activity of antioxidant enzymes, and the antioxidant capacity was significantly higher than that of the other groups. The ascorbic acid content of LED+MAP was reduced to 52 % of the original compared to 38 % of that for CK. The MDA content of LED+MAP was 3.83 times of the original compared to 8.52 times of that for CK. The electrolyte leakage of LED+MAP was 2.12 times of the original compared to 2.86 times of that for CK. With the increase of storage time, O2 concentration in MAP showed a decreasing trend and CO2 showed an increasing trend. O2 in LED+MAP showed a growing trend followed by a decreasing trend and CO2 showed a decreasing trend followed by a rising trend. LED+MAP complemented the shortcomings of the single technology and was more effective in delaying the quality deterioration of okra.

Effect of cold chain interruption on the metabolic composition and quality properties of fresh beef

Effect of cold chain interruption on the metabolic composition and quality properties of fresh beef

Numerical and experimental investigation of the flow and heat transfer characteristics for cold storage heat exchanger

Decreasing the freezing time of the cold storage heat exchanger was an effective way to reduce the risk of cold chain breakage and the fluctuation of cold chain temperature. A validated unsteady mathematical model of the cold storage heat exchanger was established to analyze the transient evolution of temperature, velocity, ice distribution, and heat transfer coefficient for different diameters of heat transfer tubes and coolant temperatures. The results showed that there were four stages of temperature in the cold storage heat exchanger, namely the primary cooling stage, the freezing stage, the secondary cooling stage, and the constant temperature stage. The ice fraction distribution and the heat transfer coefficient were inextricably linked to the water's natural convection. The average heat transfer coefficient decreased with decreasing coolant temperature and increasing heat transfer tube diameters. The freezing time decreased with the coolant temperature and the diameter of the heat transfer tubes decreasing. The tendency of the inhomogeneity of ice distribution first increased with the ice fraction up to 0.75 and then decreased with the ice fraction over 0.75. The inhomogeneity decreased with the coolant temperature increasing when the diameter of the heat transfer tubes was greater than 2 mm.

Evaluation of Lipid Oxidation Characteristics in Salmon after Simulation of Cold Chain Interruption Using Rapid Evaporation Ionization Mass Spectrometry.

Temperature fluctuations occurring during the cold chain logistics of salmon contribute to lipid oxidation. This study aimed to simulate cold chain interruption through freeze-thaw operations and evaluate the lipidomics data from salmon samples subjected to different numbers of freeze-thaw cycles by using rapid evaporative ionization mass spectrometry (REIMS) combined with an intelligent surgical knife (iKnife). The results indicated significant differences in the relative abundance of characteristic ions among the samples (p < 0.05). A total of 34 ions with variable importance for the projection values ≥1 were identified as potential biomarkers, including m/z 719.4233 ([PCC36:5-NH(CH3)3]-), m/z 337.3134 ([FAC22:1]-), m/z 720.4666 ([PEC35:6-H]-), m/z 309.2780 ([FAC20:1]-), m/z 777.4985 ([PCC40:4-NH(CH3)3]-), m/z 745.4421 ([PCC38:6-NH(CH3)3]-/[PEC38:6-NH3]-), m/z 747.4665 ([PCC38:5-NH(CH3)3]-/[PEC38:5-NH3]-), etc. The degree of lipid oxidation was found to be associated with the number of freeze-thaw cycles, exhibiting the most significant alterations in the relative abundance of lipid ions in the 8T samples. Additionally, sensory evaluation by the CIE-L*a*b* method and volatile analysis by headspace solid-phase microextraction gas chromatography-mass spectrometry demonstrated significant differences (p < 0.05) in color and odor among the salmon samples, with a correlation to the number of freeze-thaw cycles. The primary compounds responsible for alterations in salmon odor were aldehydes with lower odor thresholds. In summary, the iKnife-REIMS method accurately differentiated salmon muscle tissues based on varying levels of lipid oxidation, thus expanding the application of REIMS.

Investigation of the effect of bacteriophage cocktail on microbial quality in the case of cold chain breakage: A case study on Escherichia coli contamination in milk

Although the use of phages in food is a successful application, their activity should be tested in situations that simulate the conditions to which the food is exposed for more effective and widespread use. It is known that foods are frequently exposed to cold chain breakage, in which case the microbial balance in the food changes. Here, it was aimed to investigate the effectiveness of a phage cocktail against Escherichia coli in milk with different parameters and in the case of cold chain breakage. Two phages effective against Escherichia coli were isolated from raw milk and named as K12.2b and K12.4a. Both of these phages were determined to be highly specific to their hosts. The latent periods of phages were found to be 15 and 10 min, and the burst sizes were 348 and 24 PFU/cell, respectively. Transmission electron micrographs indicated that they belonged to Myoviridae family. For both phages, approximately 50% reduction in titers was observed at 70 °C. While K12.2b remained stable at pH 2–11, K12.4a was stable at pH 3–11. The bacterial reductions of 4.4–4.6 log-units were achieved at 25 °C for 24 h in milk, but it was limited to 1.2–2.7 log-units when the cold-chain (4 °C) was broken, and the temperature reached to 25 °C. Our study demonstrated that the efficacy of phages at real-state temperatures differs at temperatures simulating cold chain breakage.

Monitoring of Water Freeze–Thaw Cycle by Means of an Etched Single- Mode–Multimode–Single-Mode Fiber-Optic Refractometer

As an alternative to the different technologies that permit the detection of in-situ ice formation on different surfaces, this contribution proposes the design of an etched single-mode – multimode – single-mode (E-SMS) fiber-optic-based structure as a multimode interference refractometer. This sensor provides enhanced properties with respect to a basic SMS structure, including a higher sensitivity and periodical interferometry bands that can measure surrounding refractive indices with repeatability and robustness. Since ice and water refractive indices are sufficiently different, this structure has been used to detect the freezing - thawing process of water taking place inside a freezer between -20°C and +20°C. Also, this work intends to show a proof of concept of a simple technology that can be applied in different situations, such as in smart cities, avionics, structural health monitoring or even to avoid a cold chain breakage. Inside, novel developments to better understand the working operation of the E-SMS structure are shown, together with a study on how to correlate optical and thermal measurements from a refractive index point of view.

THE EFFECT OF COLD CHAIN DISRUPTION ON THE MICROBIOLOGICAL PROFILE OF CHILLED FISH

Cold chain interruption during transport of samples to the laboratory may become a confounder in food hygiene practice. This study evaluates the influence of inadequate transport conditions on the microbiological quality of fish fillets from common carp (Cyprinus carpio), Atlantic salmon (Salmo salar), and Atlantic cod (Gadus morhua) packaged in plain, vacuum, or modified atmosphere packaging (MAP). The experiments simulated the temperature increase during sample transport to 3, 5, 8, 11, 14, 17, 20, and 25 °C with exposure times of 1, 2, 3, and 4 h. Aerobic plate count (APC), psychrotrophic microorganisms count (PMC), β-D-glucuronidase-positive Escherichia coli, and Salmonella spp. were evaluated immediately after the exposure to the elevated temperature (0 h), 3 h, and 24 h after the return to the normal temperature. Variability was observed even in the initial microbial contamination of fish fillets. Storage at higher temperatures led to an increase in microbial contamination of fish fillets Different types of packaging also played a role. In non-fatty fish (cod), CO2-containing MAP led to a decrease in pH and, therefore, to lower microbial growth. In fatty fish (salmon), the presence of CO2 did not lead to the reduction in pH and the degree of microbial contamination was, therefore, not affected by this intrinsic factor. If cold chain interruption occurs during the transport of samples to the laboratory, it is necessary to perform the analysis immediately as even storage in cold conditions until the next day can lead to increased levels of microbial contamination of such samples.

Effect of Gaseous Citral on Table Grapes Contaminated by Rhizopus oryzae ITEM 18876.

Rhizopus oryzae is responsible for rapidly producing a deliquescent appearance in grape berries, generally favoured by cold chain interruptions. To counteract fruit spoilage and to meet consumer acceptance, innovative strategies based on the application of natural compounds are ongoing. Due to their biological activities, including antimicrobial ones, natural flavour compounds extend the shelf life and improve the nutritional value as well as the organoleptic properties of foods. Thus, in this work, the application of the antimicrobial citral, a flavor component of monoterpenes identified in plant and fruit essential oils, was developed and validated against one spoiler of R. oryzae. Citral, as pure compound, was first investigated in vitro against R. oryzae ITEM 18876; then, concentrations equal to the minimal inhibitory concentration (MIC) and 4-fold MIC (4MIC) value were applied on the table grape cv Italia infected with this strain and stored. The MIC value was equal to 0.0125 μL/cm3; both citral concentrations (0.0125 and 0.05 µL/cm3) were effective in counteracting the microbial decay of infected table grapes over the storage period. The HS-SPME/GC-MS method showed citral persistence in the head space of plastic trays with the infected samples; as expected, a higher content of citral isomers was found in the sample treated with 4MIC value. In conclusion, citral revealed its efficacy to counteract the onset of soft rot by R. oryzae ITEM 18876 under storage conditions. Thus, it could be successfully exploited to develop an active packaging or natural preservatives to extend table grape shelf life without affecting its quality and sensory characteristics, whilst also satisfying the consumer demand for natural preservative agents.

Dual bacterial strains TTI for monitoring fish quality in food cold chain.

Most microbial time-temperature indicators (TTIs) considered only one spoilage strain. This research compared single and dual spoilage strains-based microbial TTI for quality changes of chilled grouper fish (Epinephelus fuscoguttatus x E. lanceolatus) fillet products during distribution. The next-generation sequencing (NGS) and traditional plate count approach showed that Pseudomonas fragi and Vibrio parahaemolyticus were specific spoilage bacteria at 7 and 15°C. A dual-strain TTI response provides more accurate results than a single-strain TTI and provides an irreversible color change from yellow to reddish-brown, showing levels of fish freshness. The microbial TTI comprises fish spoilage bacteria strains with 3 log CFU/ml, a nutrient broth supplemented with 2% NaCl as a medium, and phenol red with 0.25 mg/ml as a pH indicator. Overall, this study points to the applicability of a dual-strain microbial TTI as a valuable tool for monitoring fish quality changes during cold chain break condition.

Reliable stability prediction to manage research or marketed vaccines and pharmaceutical products. “Avoid any doubt for the end-user of vaccine compliance at time of administration”

A major challenge for the pharmaceutical/vaccine industry is to anticipate and test/control product stability, regardless of the time/temperature profile of the product, from release to administration. Current empirical stability protocols performed to ensure product stability remain limited to the prediction of product stability in a thermal excursion (cold chain break) during their long-term storage. As recently recommended by the World Health Organization, mathematical models can be used for shelf-life and stability predictions. Therefore, various approaches have been published with good performance for simple chemical reactions. However, for biomolecules/vaccines, more complex reaction profiles require more complex models to predict their stability with a good level of confidence. This complexity constitutes a real scientific challenge because the number of model parameters increases with model complexity and need to be balanced with the limited number and quality of the available experimental data.We have developed a dedicated method/software based on different vaccines/pharmaceutical case studies. This predictive method considers phenomenological models, five levels of model confidence assessment, predictive quality value and simulated designs of experiment to improve and define the limits within which the prediction models can be used, and to increase model/prediction confidence to the required regulatory and scientific levels. This artificial intelligence system should help to avoid any doubt of stability at time of vaccine injection.

Non-destructive techniques for mitigating losses of fruits and vegetables

Fruits and vegetables losses and wastage have massive impacts on the economy, as they constitute about half of the 1.3 billion tons of food annually lost; on the environment, because its elimination generates 10%-12% of greenhouse gases, and on society, because one of every four calories produced is not consumed. Losses are generated during production, postharvest, and marketing periods. In developing countries, only in postharvest, losses reach between 40% and 50% depending on the product considered. Losses can be grouped into physical, biological, and physiological, and their reduction constitutes a challenge that countries are attempting to tackle through both individual and collaborative actions. For applying successful mitigation strategies, not only their quantification but also the identification of factors and occasions in which losses occur are of utmost importance. In this sense, the use of non-destructive techniques is especially useful as such techniques facilitate the detection of physical damages before they are visible or the identification of pathogens before they develop. Other aspects include the possibility of monitoring refrigeration conditions during storage and transport, identifying the occurrence of a cold chain break, and making it possible to rectify the same. In this paper, various techniques applicable to the identification and reduction of losses are reviewed.

Molecular Thermal Motion Modulated Room-Temperature Phosphorescence for Multilevel Encryption.

The stimulus-responsive room-temperature phosphorescence (RTP) materials have become an increasingly significant topic in the fields of bioimaging, sensing, and anticounterfeiting. However, this kind of materials is scarce to date, especially for the ones with delicate stimulus-responsive behavior. Herein, a universal strategy for multilevel thermal erasure of RTP via chromatographic separation of host-guest doping RTP systems is proposed. The tunable host-guest systems, matrix materials, heating temperature, and time are demonstrated to allow precise six-level data encryption, QR code encryption, and thermochromic phosphorescence encryption. Mechanistic study reveals that the thermal-responsive property might be attributed to molecular thermal motion and the separation effect of the silica gel, which provides expanded applications of host-guest RTP materials such as cold chain break detection. This work offers a simple yet universal way to construct advanced responsive RTP materials.

Evaluation of the diagnostic potential and DIVA capability of recombinant LigBCon1-5 protein of Leptospira interrogans serovar Pomona in canine leptospirosis.

Canine leptospirosis is a serious public health concern. This study aims to investigate the feasibility of conserved first to fifth domains of recombinant Leptospira immunoglobulin like protein B antigen (rLigBCon1-5) as a serodiagnostic marker for detecting canine leptospirosis. A total of 340 unvaccinated canine serum samples were screened using microscopic agglutination test (MAT) and rLigBCon1-5 based immunoglobulin G (IgG) indirect-enzyme-linked immunosorbent assay (I-ELISA). Further, 60 vaccinated canine sera were screened using MAT and rLigBCon1-5 based latex agglutination test (LAT). Microscopic agglutination test results revealed seropositivity of 28.6%. The relative sensitivity, specificity, and accuracy of IgG I-ELISA in comparison to MAT were 100%, 96.0%, and 97.2%, respectively. Out of 60 vaccinated sera, 46 sera reacted with MAT alone, and eight sera reacted by both tests, while six sera were non-reactive with both tests. Anti-LigB antibodies were detected in eight canine sera by rLigBCon1-5 based LAT. In five LAT reactive sera, agglutinins of locally circulating Leptospira serovars Grippotyphosa (n=4) and Australis (n=1) were detected. In three LAT reactive sera, agglutinins against Icterohaemorrhagiae (n=3) produced due to natural infection were present. Immunoglobulin G based indirect ELISA assay (IgG I-ELISA) can be employed as an alternative test instead of MAT. rLigBCon1-5 based LAT detected anti-LigB antibodies in eight vaccinated sera where the vaccine failure occurred partially or totally due to the limited efficacy spectrum of Nobivac® RL and cold chain breakage. This vaccine could not provide cross-protection against locally circulating Leptospira serovars. The recombinant LigBCon1-5 antigen based LAT possesses capability of differentiating infected from vaccinated individuals (DIVA capability) when employed as a pen-side test for detecting canine leptospirosis.

A survey of the usage and storage practices of veterinary medicines among communal cattle farmers in the Kabbe South Constituency, Zambezi region.

Veterinary medicines are an indispensable tool for animal disease control and prevention. Misuse, improper handling and storage can render veterinary medicines less effective. A cross-sectional study was carried out on 60 cattle farmers in the Kabbe South Constituency of the Zambezi region in Namibia. The objective of the study was to find out the usage and storage practices of veterinary medicines. Selected farmers were interviewed using semi-structured questionnaires. Results of the study showed that the majority of respondents were males (78.3%, n=47) with at least primary school level education. Overall, farmers acquired and used 13 different types of veterinary medicines from licensed shops and pharmacies (73.4%, n=44), the state veterinary office (23.3%, n=14) and from unregistered veterinary medicine agents (3.3%, n=2). The medicines comprised of antibiotics (n=4); vaccines (n=3); combination of ectoparasiticide and anthelmintic (n=2), ectoparasiticide (n=1), anthelmintic (n=1) and vitamins (n=2). Although 36.7% (n=22) of the farmers owned or had access to a refrigerator, the majority (86.7%, n=52) did not maintain the cold chain. Most of the respondents (93.3%, n=56) self-diagnosed animal diseases and decided on the treatment without consulting a veterinarian. Oxytetracycline was the most commonly used veterinary medicine and was used at less than the recommended dose of 1ml/10kg by most respondents (83.3%, n=50). Although farmers sourced veterinary medicines from licensed retailers, the break in the cold chain and the under dosing of medicines may impair effectiveness. Self-diagnosis and treatment of animal diseases promotes misuse and the development of antibiotic resistant bacteria in cattle which may render antibiotics on the market less effective. The training of all stakeholders along the veterinary medicine value chain in the region is recommended.

AFM imaging of extracellular ice nucleators.

Ice nucleators are substances that can initiate nucleation of pure water at and above -10 °C.Some plant pathogens possess a gene which encodes for a protein that acts as an ice nucleator, activity of which is enhanced when it is combined with the sugar and lipid components from the cell membrane. This matter retains its ice nucleation activity even after it is detached from the cell wall, and is termed extracellular ice nucleator (ECIN). In this paper, surface morphology of ECINs was investigated using atomic force microscopy (AFM) in tapping mode. ECINs were immobilized onto polyelectrolyte multilayers using the layer by layer deposition method. Effect of layer build-up, method of ECIN production, and polyelectrolytes used for multilayer fabrication were investigated. Globular and rod-like structures were observed on the AFM images of the nano-thin ECIN layers. Activity of ECINs, tested in food solutions in earlier studies, was retained when applied as a nano-thin layer onto a silicon wafer surface. Protein aggregate sizes decreased when higher centrifugation speeds were applied, and ice nucleation activity also decreased. Nucleation occurred faster and at higher temperatures when substrates were immersed in solutions of higher ECIN concentration, whereas number of bilayers formed did not have a significant effect. Higher concentration ECIN dipping solutions also led to the formation of thicker and denser ECIN layers as observed via AFM imaging. PRACTICAL APPLICATION: This study demonstrates the properties of nano-thin ECIN layers, which can crystallize pure water into ice at higher temperatures and in shorter time. Accelerating ice nucleation can potentially be utilized to freeze liquids in shorter time hence using less energy, or improve frozen foods' stability against the risk of cold chain breakage.

Effect of Cold Chain Logistic Interruptions on Lipid Oxidation and Volatile Organic Compounds of Salmon (Salmo salar) and Their Correlations With Water Dynamics.

Lipid oxidation and water migration are important factors in the quality changes of aquatic products. This study investigated the relationship between water migration and lipid oxidation in salmon filets under four different storage conditions (control: 0°C; T1: 4°C; T2 and T3: two temperature fluctuation groups) by detecting thiobarbituric acid–reactive substances, changes of fatty acids, and volatile organic compounds (VOCs), and other quality indicators including redness, microorganism, total volatile basic nitrogen (TVB-N), and water-holding capacity (WHC) were also measured. The results of low-field nuclear magnetic resonance (LF-NMR) showed that more trapped water (T22) turned to form free water (T23) in groups suffering temperature fluctuations. A more significant decrease in fatty acids was found in T2 and T1 groups, especially oleic acid (C18:1n9c), linoleic acid (C18:2n6c), and palmitic acid (C16:0). The VOCs with off-flavors (1-penten-3-ol, 2-penten-1-ol, (Z)-, 1-octen-3-ol, hexanal) in the groups suffered from simulated cold chain interruptions increased faster than the other two groups during storage. T22 was negatively correlated (p < 0.05) with stearic acid (C18:0), 1-penten-3-ol, hexanal, and nonanal, whereas T23 was positively correlated with 1-penten-3-ol, hexanal, and heptanal. Therefore, the temperature fluctuation accelerated the loss of polyunsaturated fatty acids and the increase of unpleasant odors related to water migration.

Influence of reduced levels or suppression of sodium nitrite on the outgrowth and toxinogenesis of psychrotrophic Clostridium botulinum Group II type B in cooked ham

Outgrowth and toxinogenesis of Clostridium botulinum Group II (non-proteolytic) type B were studied in cooked ham prepared with different NaNO2 (ranging from 0 to 80 mg/kg) and sodium chloride (NaCl, ranging from 12 to 19 g/kg) incorporation rates. Cured ground pork batters were inoculated with a cocktail of 3 strains of C. botulinum Group II type B at 3.5 log10 CFU/g, portioned and samples of 50 g were vacuum packed then cooked and cooled based on thermal processing employed by the meat processing industry. These cooked ham model samples were stored under reasonably foreseeable conditions of use and storage i.e. for 14 days at 4 °C, followed by a cold chain break for 1 h at 20 °C then up to 33 days at 8 °C. Storage times and temperatures were used to mimic those commonly encountered along the supply chain. Enumeration of C. botulinum and detection of the botulinum neurotoxin type B (BoNT/B) were performed in triplicate at different storage times. Under these experimental conditions, incorporation rates of NaNO2 ≥ 30 mg/kg prevented the outgrowth and toxinogenesis of C. botulinum Group II type B in the cooked ham model, regardless of the NaCl concentrations tested. In contrast, total removal of nitrite allowed outgrowth and toxin production during storage of the processed meat product. Results showed that the maximum ingoing amount of nitrite (i.e. 150 mg/kg) that may be added according to the EU legislation (Regulation (EC) No 1333/2008) can be reduced in cooked ham while still ensuring control of C. botulinum Group II type B. According to the multiple factors that could affect C. botulinum behavior in processing meat products, outgrowth and toxin production of C. botulinum should be evaluated on a case by case basis, depending on the recipe, manufacturing process, food matrix and storage conditions.

Performance of Lactobacillus paracasei 90 as an adjunct culture in soft cheese under cold chain interruption

In this work, we simulated cold chain interruptions in soft cheeses of high-moisture to assess their impact on ripening, putting attention on the behaviour of an adjunct culture of Lactobacillus paracasei 90 (L90) when it was added. Temperature variation did not change starter culture levels but it significantly increased L90 population at 60 days in cheeses with cold chain interruption. Cold chain interruptions and adjunct culture led to an increase of the proteolysis levels and produced changes in the carbohydrate fermentation, volatile compounds profiles and sensory scores. In cheeses with cold chain interruptions, L90 did not cause any defects and maintained its capacity of improving flavour and odour intensities by increasing the levels of diacetyl and acetoin, and decreasing pungent taste and compounds associated with rancidity. In addition, samples with adjunct culture presented increased levels of lactic acid without being perceived as a defect by the sensory panel.