PhD Vermeiren Lieve Compleet - Hogeschool Gent

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• Sub-objective 5 Chapter 5 aimed at testing whether it was possible to extend the application field of the selected protective cultures. More specific, the usefulness of the cultures to control growth of L. monocytogenes and to improve in this way the food safety of CMP was investigated. The introduction of the new regulation on microbial criteria in food (the current Commission Regulation (EC) No 2073/2005) (European Commission, 2005) makes this study even more relevant. Furthermore, one of the objectives of chapter 5 was also to test the influence of inoculum level, storage temperature (4°C versus 7°C) and packaging type (vacuum versus modified atmosphere) on the biopreservative effect. • Sub-objective 6 The previous chapters had resulted in the selection of the promising protective culture Lactobacillus sakei 10A. However, up to that moment, the action of the culture was only tested on a model product. Therefore, it was the objective of chapter 6 to validate the antagonistic effect of L. sakei 10A towards the spoilage organisms Leuconostoc mesenteroides and Brochothrix thermosphacta on the one hand and towards the food born pathogen L. monocytogenes on the other hand when this culture is applied to several industrially prepared cooked meat products. Furthermore, large efforts were made to obtain a better understanding of the impact of the protective culture L. sakei 10A on the sensory properties of these products. In this chapter, L. sakei 10A was in fact considered as a particular case study from which conclusions on protective cultures in general could be derived. • Sub-objective 7 The work presented in chapter 7 tried to elucidate the mechanism by which the nonbacteriocinogenic L. sakei 10A inhibits the growth of L. monocytogenes. • Sub-objective 8 Finally, it was the objective of chapter 8 to broaden our view on biopreservation by investigating biopreservation of vacuum packaged cooked meat products by means of bacteriophages. Introduction and objectives ix
Chapter 1: Antagonistic micro-organisms for biopreservation of food products Chapter 2: Isolation, screening and selection of protective cultures Chapter 3: Characterisation of spoilage organisms of cooked meat products Chapter 4: Interaction between protective cultures and spoilage organisms Chapter 5: Interaction between protective cultures and L. monocytogenes Figure 0.1. Outline of this <strong>PhD</strong> Chapter 6: Application to CMP: Effectiveness and impact on sensory quality Chapter 7: Mechanism of inhibition Chapter 8: Biopreservation by means of bacteriophages Introduction and objectives x
Page 1: Hogeschool Gent Biopreservation of
Page 4 and 5: ir. Lieve Vermeiren Biopreservation
Page 6 and 7: Woord vooraf Proefbuizen, labojasse
Page 8: Table of contents
Page 11 and 12: 3.4. EFFECT OF PROTECTIVE LAB ON TH
Page 13 and 14: 1. INTRODUCTION....................
Page 15 and 16: 2.8. STATISTICAL ANALYSES 189 3. RE
Page 18 and 19: Introduction and objectives In rece
Page 22: Summary
Page 25 and 26: Chapter 3 presented a systematic st
Page 27 and 28: 10A and an atmosphere containing 50
Page 30: Samenvatting
Page 33 and 34: werden deze stammen beschouwd als m
Page 35 and 36: ewaartemperatuur (4°C versus 7°C)
Page 37 and 38: In-vitro testen toonden aan dat de
Page 40 and 41: Chapter 1 Antagonistic micro-organi
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Page 44 and 45: 1.4.3. The genus Pediococcus This g
Page 46 and 47: taxonomy) and the present phylogene
Page 48 and 49: 1.5.1. Fermentation end-products 1.
Page 50 and 51: The ability of lactic acid to rotat
Page 52 and 53: 1.5.2. Bacteriocins Bacteriocins, p
Page 54 and 55: molecule inserts into the membrane
Page 56 and 57: 1.5.3. Other antagonistic systems 1
Page 58 and 59: explains why CMP, immediately after
Page 60 and 61: Weissella Weissella viridiscens has
Page 62 and 63: 2.3.3.3. Discolouration Green disco
Page 64 and 65: eported an incidence of L. monocyto
Page 66 and 67: The use of micro-organisms or their
Page 68 and 69: 3.2.2. Organic acids In general, re
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Furthermore, protective LAB can be
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Fish, fish products and seafood Spo
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Table 1.3. Effect of (non-)bacterio
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performance as a biopreservative in
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Table 1.6. Studies on the effect of
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prevent them from growth of food bo
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The application of the host-specifi
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Multiplicity of infection (MOI) Pha
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using Leuc. carnosum 4010 in frankf
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activity of LAB in general, this se
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effect (Gram et al., 2002). Several
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for one or more of these vitamins o
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clinical cases, patients were immun
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different degrees and classify them
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this way an equal distribution over
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Chapter 2 Evaluation of meat born l
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temperatures, the characterisation
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dextranicum LMG 6908 T , Leuc. carn
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2.6. Behaviour of 12 selected putat
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considered as unacceptable. Finally
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From the 74 remaining strains, only
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Among the isolates, 76% (28/37) was
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Within the group of isolated strain
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with fast growth rates at low tempe
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pH 6.3 6.2 6.1 6.0 5.9 5.8 5.7 0 5
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34th day of the storage period, alt
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Table 2.5. Summary of the LAB-count
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Chapter 3 In-vitro and in-situ grow
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1. Introduction A considerable part
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7°C and revived by transferring a
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The sensory quality of cooked ham s
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lesser extent compared to the LAB s
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LC2 and LM3 not significantly decre
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Sensory rejection was mainly based
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log10(cfu/g), respectively. It migh
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Chapter 4 Co-culture experiments de
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1. Introduction Interest in the rol
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growth characteristics, antibacteri
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1 g/l Peptone (Oxoid)) was prepared
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were sensitive to 8/11 tested antib
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Log10(cfu/g) Log10(cfu/g) 9 8 7 6 5
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On the other hand, no significant (
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Table 4.3. Evolution of the glucose
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Log10(cfu/g) Log10(cfu/g) 9 8 7 6 5
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day 28 in the HG-product. However,
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glucose. Buchanan & Bagi (1997) als
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Chapter 5 The interaction of the no
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1. Introduction Several authors hav
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(3) an interaction study at 7°C be
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3. Results and discussion The chemi
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Log10(cfu/g) 9 8 7 6 5 4 3 2 1 0 0
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Clearly, the growth of L. sakei 10A
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Table 5.2. Evolution of the pH of t
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Chapter 6 The sensory acceptability
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1. Introduction During the last dec
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mixture of Leuc. mesenteroides LM2
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to a sensory panel of 18 non-traine
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inoculation, 200 g portions of prod
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Buffering capacity (mmol lactic aci
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where LAB-growth results in sensory
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3.2.1. Antagonistic activity of L.
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In all five products, L. sakei 10A
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the glucose consumption in 10A-samp
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In general, CMP with such low pH-va
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3.3. Discussion 3.3.1. Antagonistic
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that cooked ring sausages were deem
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Chapter 7 The contribution of lacti
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1. Introduction The last two decade
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Table 7.1. Composition of the diffe
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In all three experiments, growth of
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2.5.2. Challenge experiment in CFS
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3. Results and discussion 3.1. Co-c
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However, cell numbers were analysed
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Log10(cfu/ml) or pH Log10(cfu/ml) o
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Log10(cfu/ml) Log10(cfu/ml) 10 9 8
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Log10(cfu/ml) Log10(cfu/ml) 9 8 7 6
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that case the pH of the CFS would h
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Log10(cfu/ml) Log10(cfu/ml) 9 8 7 6
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these experiments when there was st
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Chapter 8 Treatment with bacterioph
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1. Introduction Listeria monocytoge
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(7°C and 30°C). Experiments were
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L. monocytogenes cocktail, 100 µl
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3. Results and discussion 3.1. Effe
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susceptibility of the genus Listeri
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end-point for the microbial shelf-l
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therefore, be sufficient to control
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contaminated cooked meat products,
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General discussion, conclusions and
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possible that the bacteriocin was n
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manufactured cooked meat products (
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deviations can be prevented and led
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List of abbreviations
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pfu plaque forming unit PPS Pepton
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References 1. Aasen, I.M., Markusse
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26. Berry, E.D., Liewen, M.B., Mand
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50. Buncic, S., Avery, S.M. & Moorh
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75. Devlieghere, F., Debevere, J. &
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99. Foegeding, P.M., Thomas, A.B.,
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125. Hudson, J.A., Billington, C.,
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150. Korkeala, H., Alanko, T., Mäk
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174. Marceau, A., Zagorec, M. & Cha
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nonbacteriocinogenic Carnobacterium
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style green olive fermentations. Ap
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253. Stratford, M. (2000). Traditio
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277. Vitas, A.I. & Garcia-Jalon, V.
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Curriculum vitae Curriculum vitae L
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of Listeria monocytogenes by the no
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2. ILSI Europe 2nd International Sy
Page 306:
13. EFSA Colloquium On Microorganis
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PhD Vermeiren Lieve Compleet - Hogeschool Gent

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