Tissue classification for MRI of thigh using a modified FCM method.

Fuzzy C-means (FCM) has been frequently used to image segmentation in order to separate objects. The most used segmentation attribute is grey level of pixels. Nevertheless, this method can not identify complex image objects because grey level can not take into account all visual information. This paper describes a modified FCM method for tissue classification which integrates separation and fusion operation of partition tree with expert knowledge. Our method has been applied to 26 MRI (Magnetic Resonance Imaging) images of thigh for localizing four main anatomical tissues: muscle, adipose tissue, cortical bone, and spongy bone. A testing dataset of 6500 representative points has been created by an expert. Using our method, we obtain a high classification rate (95.73%) in the test dataset, which largely improved the classification results obtained from existing methods.

The interaction of the non-bacteriocinogenic Lactobacillus sakei 10A and lactocin S producing Lactobacillus sakei 148 towards Listeria monocytogenes on a model cooked ham.

Two lactic acid bacteria, Lactobacillus sakei subsp. carnosus (10A) and lactocin S producing Lactobacillus sakei 148 (LS5), were examined for their usefulness as protective culture in the biopreservation of cooked meat products. Co-culture experiments on a model cooked ham (MCH) between 10A or LS5 and a cocktail of three Listeria monocytogenes strains were performed to examine the influence of inoculum level (10(5) vs. 10(6)cfu/g), storage temperature (4 vs. 7 degrees C) and packaging type (vacuum-packaging vs. modified atmosphere-packaging). At 7 degrees C, applying Lactobacillus sakei 10A at 10(6) cfu/g limited the growth of Listeria monocytogenes to <1 log(10) cfu/g during 27 days, whilst an application level of 10(5) cfu/g failed to prevent growth to unacceptable levels. Lactobacillus sakei LS5 did not demonstrate an antagonistic effect towards Listeria monocytogenes. Lowering the temperature to 4 degrees C or switching from vacuum-packaging to modified atmosphere packaging (MAP) did not influence the ability of strain 10A to grow on the MCH, as its dominance did not change. A combination of strain 10A and 4 degrees C or a MAP containing 50% CO(2) completely inhibited the growth of Listeria monocytogenes. Sensory assessments and pH measurements confirmed that 10A, even when present at a high level for prolonged storage times, did not acidify the cooked ham to a point of sensory rejection.

Co-culture experiments demonstrate the usefulness of Lactobacillus sakei 10A to prolong the shelf-life of a model cooked ham.

This study investigated the usefulness of two selected lactic acid bacteria, Lactobacillus sakei subsp. carnosus (10A) and the lactocin S producing L. sakei 148 (LS5), to extend the shelf-life of cooked meat products. The interaction between these potential protective cultures and the spoilage organisms, Leuconostoc mesenteroides (LM4) and Brochothrix thermosphacta (BT1), were examined in co-culture studies on a model cooked ham product at 7 degrees C under vacuum packaged conditions. Furthermore, the influence of the glucose content of the model cooked ham on the interaction phenomena was investigated. When artificially contaminating the model cooked ham with BT1 at 10(2) cfu/g in combination with 10A at 10(5) cfu/g, the growth of BT1 was significantly slower compared to a simultaneous mono-culture experiment. In a similar experiment with LM4, LM4 reached a level of 10(7) cfu/g +/-14 days later when LM4 grew together with 10A compared to its growth in mono-culture. The lactocin S producing LS5 did not demonstrate an inhibitory action towards LM4 or BT1 and is therefore not useful as protective culture on cooked meat products. The glucose level of the model cooked ham had no influence on the observed antagonistic interactions of 10A towards LM4 or BT1, indicating that the action of the biopreservative 10A in cooked meat products is independent of the substrate glucose.

The sensory acceptability of cooked meat products treated with a protective culture depends on glucose content and buffering capacity: A case study with Lactobacillus sakei 10A.

Biopreservation has been proven to be a promising natural preservation technique, but the impact of protective cultures on the sensory properties of cooked meat products (CMP) is not well documented. This work presents a case study on the protective culture Lactobacillus sakei 10A to obtain a clear view on the real consequences of using protective cultures on the sensory quality of CMP. A preliminary screening study on 13 different CMP and more elaborate application trials at 7°C on vacuum packaged pâté, cooked ham, cooked sausage and two cooked poultry products demonstrated that L. sakei 10A inhibits the endogenous LAB-flora, Leuconostoc mesenteroides, Brochothrix thermosphacta and Listeria monocytogenes. Despite these promising antagonistic effects, the application of L. sakei 10A to CMP was in some cases limited by a significant acidification resulting in an acid taste of the product. This was most obvious in pâté and cooked sausage and less obvious in cooked turkey fillet. From the results a hypothesis could be derived that high buffering capacity and low glucose content are key elements to avoid sensory deviations when applying protective cultures on CMP.

In vitro and in situ growth characteristics and behaviour of spoilage organisms associated with anaerobically stored cooked meat products.

AIMS: Understanding spoilage caused by different types of spoilage organisms, associated with vacuum-packaged sliced cooked meat products (CMP). METHODS AND RESULTS: First, strains were characterized in a broth at 7 degrees C under anaerobic conditions to compare their growth rate, acidifying character and metabolite production under conditions simulating refrigerated vacuum-packaged conditions. Brochotrix thermosphacta grew faster than the lactic acid bacteria (LAB). Within the group of the LAB, all strains grew fast except Leuconostoc mesenteroides subsp. dextranicum and Leuconostoc carnosum. Secondly, the organisms were inoculated on a model cooked ham to better understand the relationship between spoilage, microbial growth, pH, metabolite production and accompanying sensory changes. Most rapidly growing strains were Leuc. mesenteroides subsp. mesenteroides followed by B. thermosphacta, while Leuc. mesenteroides subsp. dextranicum and Leuc. carnosum grew very slowly compared with the other LAB. Brochotrix thermosphacta caused sensory deviations at a lower cell number compared with the LAB. The related pH changes, metabolite production and sensory perception are presented. CONCLUSIONS: In this pure culture study, B. thermosphacta and Leuc. mesenteroides subsp. mesenteroides had the highest potential to cause rapid spoilage on CMP. SIGNIFICANCE AND IMPACT OF THE STUDY: A systematic study on the behaviour of spoilage organisms on a model cooked ham to establish the relationship between microbial growth, pH, metabolite formation and organoleptic deviations.

Evaluation of meat born lactic acid bacteria as protective cultures for the biopreservation of cooked meat products.

In this study, 91 strains, originating from meat products, were subjected to a step-by-step screening and characterisation to search for potential protective cultures to be used in the cooked cured meat industry. Strains were first tested on their homofermentative and psychrotrophic character and salt tolerance. Secondly, the antibacterial capacities towards Listeria monocytogenes, Leuconostoc mesenteroides, Leuconostoc carnosum and Brochotrix thermosphacta were determined in an agar spot test. In total, 38% of the tested strains were inhibitory towards all indicator strains. However, 91%, 88% and 74% of the strains could inhibit, respectively, L. monocytogenes, B. thermosphacta and Leuc. mesenteroides. Finally, 12 strains, with the highest antibacterial capacities, were evaluated on their competitive nature by comparing their growth rate, acidifying character and lactic acid production at 7 degrees C under anaerobic conditions in a liquid broth. All 12 strains, except for a bacteriocin producing Lactobacillus plantarum strain and the lactocin S producing Lactobacillus sakei 148, combined a fast growth rate with a deep and rapid acidification caused by the production of high levels of lactic acid. The 12 selected strains were then further investigated for their growth capacity on a model cooked ham product to establish whether the presence of these cultures on the ham did not negatively influence the sensory properties of the ham. All strains grew in 6 days at 7 degrees C from a level of 10(5)-10(6) to 10(7)-10(8) cfu/g and again the bacteriocin producing L. plantarum strain was the slowest growing strain. As the glucose level of the model cooked ham product was low (0.09+/-0.03%), growth of the putative protective cultures resulted in glucose depletion and a limited lactic acid production and accompanying pH decrease. Cooked ham inoculated with isolates 13E, 10A, 14A (all three identified as L. sakei subsp. carnosus by SDS-PAGE) and with strains L. sakei 148 (LS5) and L. sakei subsp. carnosus SAGA 777 (LS8) were not rejected by the sensory panel at the 34th day of the vacuum packaged storage at 7 degrees C. Therefore, these strains could have potential for the use as protective culture in cooked meat products.

Evaluation of the potential of meat born lactic acid bacteria for use as protective cultures in the biopreservation of cooked meat products.

In this study, 97 lactic acid bacteria were subjected to a step-by-step screening and characterisation to search for potential protective cultures to be used in the cooked cured meat industry. Strains were first tested on their homofermentative and psychrotrophic character and salt tolerance. Secondly, the antibacterial capacities towards Listeria monocytogenes, Leuconostoc mesenteroides, Leuconostoc carnosum and Brochotrix thermosphacta were determined in an agar spot test. Finally, 12 selected strains were evaluated on their competitive nature by comparing their growth rate, acidifying character and lactic acid production at 7 degrees C under anaerobic conditions.

Effectiveness of some recent antimicrobial packaging concepts.

A new type of active packaging is the combination of food-packaging materials with antimicrobial substances to control microbial surface contamination of foods. For both migrating and non-migrating antimicrobial materials, intensive contact between the food product and packaging material is required and therefore potential food applications include especially vacuum or skin-packaged products, e.g. vacuum-packaged meat, fish, poultry or cheese. Several antimicrobial compounds have been combined with different types of carriers (plastic and rubber articles, paper-based materials, textile fibrils and food-packaging materials). Until now, however, few antimicrobial concepts have found applications as a food-packaging material. Antimicrobial packaging materials cannot legally be used in the EU at the moment. The potential use would require amendments of several different legal texts involving areas such as food additives, food packaging, hygiene, etc. The main objective of this paper is to provide a state of the art about the different types of antimicrobial concepts, their experimental development and commercialization, and to present a case study summarizing the results of investigations on the feasibility of a low-density polyethylene (LDPE)-film containing triclosan to inhibit microbial growth on food surfaces and consequently prolong shelf-life or improve microbial food safety. In contrast with the strong antimicrobial effect in in-vitro simulated vacuum-packaged conditions against the psychrotrophic food pathogen L. monocytogenes, the 1000 mg kg(-1) containing triclosan film did not effectively reduce spoilage bacteria and growth of L. monocytogenes on refrigerated vacuum-packaged chicken breasts stored at 7 degrees C.