The effect of heat stress on freeze-drying and conservation of Lactococcus

Ziadi, Manel; Touhami, Youssef; Achour, M.; Thonart, P.; Hamdi, Moktar

doi:10.1016/j.bej.2005.02.001

Cited by 28 publications

(19 citation statements)

References 11 publications

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“…For example, P. fluorescens BTP1 decreased from 10.30 log 10 to 4.5 log 10 at 60°C after 8 h storage, to 5.7 log 10 after 28 days storage at 37°C and to 9.2 log 10 after 60 days storage at 4°C. The present results basically confirm literature data (An-Erl King et al, 1998;Achour et al, 2001;Picot and Lacroix Ziadi et al, 2005). Strain BB2 performs better than BTP1 and PI9 at 37 and 60°C.…”

Section: Resultssupporting

confidence: 82%

“…Strain BB2 performs better than BTP1 and PI9 at 37 and 60°C. Some work demonstrated, that experimental determination of bacterial survival at higher temperatures can be successfully used to predict bacterial survival for lower temperature (Achour et al, 2001;Hernández et al, 2006;Ziadi et al, 2005;Yao et al, 2008). Figure 2 shows the survival rate curves of P. fluorescens strains.…”

Section: Resultsmentioning

confidence: 99%

“…AST can be also used to study the stability of freeze-dried bacteria. Supportive work was previously reported (An-Erl King et al, 1998;Achour et al, 2001;Ziadi et al, 2005;Hernández et al, 2006;Aguirre et al, 2009). The effect of different temperature on the survival of Gram positive bacteria was studied.…”

Section: Introductionmentioning

confidence: 99%

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Accelerated storage testing of freeze-dried Pseudomonas fluorescens BTP1, BB2 and PI9 strains

Mputu¹,

Destain²,

Noki³

et al. 2012

Afr. J. Biotechnol.

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Freeze-dried cultures of Pseudomonas fluorescens are used in agriculture and microbiological industry. However, P. fluorescens is very susceptible to damage during freeze-drying and subsequent storage and it would be useful to increase culture viability during storage. The viability of freeze-dried P. fluorescens strains (BTP1, PI9 and BB2) was evaluated by using the Arrhenius model. This model was described by measuring the reaction rate constants (D or k) and temperature sensitivity of rate constant (z or Ea). The freeze-dried P. fluorescens strains were stored in glass tubes at 60, 37 and 4°C for 8 h, 28 days and two months, respectively. D value decreased or k increased with an increase of the storage temperature. By comparing their decimal reduction time (D), we observed that BB2 strain was more resistant than BTP1 and PI9 at 37 and 60°C. The activation energy of all P. fluorescens strains were not significantly different and thermal inactivation may occur by the same mechanism. Thus, it was possible to compare rate constants of survival for the freeze-dried P. fluorescens strains. These results will be useful to the development of improved reference materials and samples held in culture collections.

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Section: Resultssupporting

confidence: 82%

Section: Resultsmentioning

confidence: 99%

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Accelerated storage testing of freeze-dried Pseudomonas fluorescens BTP1, BB2 and PI9 strains

Mputu¹,

Destain²,

Noki³

et al. 2012

Afr. J. Biotechnol.

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“…lactis var. diacetylactis [43], Lactobacillus paracasei [24], Streptococcus thermophilus [44] and Lactobacillus acidophilus [45]. As well as frozen cultures such as Lactobacillus rhamnosus [46], Lb.…”

Section: Discussionmentioning

confidence: 99%

Influence of Freezing and Freeze Drying on Intracellular Enzymatic Activity and Autolytic Properties of Some Lactic Acid Bacterial Strains

Kandil¹,

Soda²

2015

AiM

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Lactic acid bacteria possess several interesting properties of great economic importance. Improvement and stabilization of these industrially important features are an active research area at the present time. The objectives of this work are to study the effect of freezing and freeze-drying on the survival rate, autolytic activity and intracellular enzymatic activity of the main species of lactic acid bacteria used in the dairy industry. The article focused on several characteristics that were not well covered in the past. The obtained results revealed that both preservation methods have a significant effect on viability, autolytic activity and intracellular enzymatic activity. After six months of storage we found that frozen cultures exhibited higher survival rate, higher rate of intracellular enzymatic activity and lower rate of autolysis. The impact of conservation treatments was only strain specific in the case of survival rate. The results obtained lead to the selection of the best preservation method for the selected cultures based on survival rate, autolytic activity and intracellular enzymatic activity.

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“…These strains exhibit a higher acidification rate and a large range of aroma compounds (Ziadi et al 2008(Ziadi et al , 2010. The production and conservation of these starters in semi-synthetic medium (M17) and corn steep have been investigated in our laboratories (Ziadi et al 2005).…”

Section: Introductionmentioning

confidence: 99%

Kinetic study of Lactococcus lactis strains (SLT6 and SLT10) growth on papain-hydrolysed whey

Ziadi

Rezouga

Bouallagui

et al. 2010

World J Microbiol Biotechnol

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The effect of controlled whey hydrolysis by papain on growth of two lactic acid bacteria isolated from artisanal Leben: Lactococcus lactis var. diacetylactis (SLT6 and SLT10) was investigated. The higher biomass and maximum specific growth rate (l max ) were obtained after 30 min of hydrolysis. HPLC analysis of peptides showed that whey hydrolysis reduced the amount of peptides of MW [ 400 Da and increased those peptides of MW \ 400 Da. The two studied strains exhibited different peptide requirements. The pH-controlled batch cultures in 30 min hydrolysed whey followed the Monod kinetic for growth and for lactate production. The values of the key kinetic constants were: maximum specific growth rate (l max ), 1.08 and 0.56 h -1 ; yield biomass on lactose (Y x/s ), 0.20 and 0.18 g g -1 and saturation constant K s , 4.2 and 2.8 g L -1 for SLT6 and SLT10, respectively. When compared with batch experimental data, the model provided good predictions for growth, lactose utilisation and lactate production profiles.

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The effect of heat stress on freeze-drying and conservation of Lactococcus

Cited by 28 publications

References 11 publications

Accelerated storage testing of freeze-dried Pseudomonas fluorescens BTP1, BB2 and PI9 strains

Accelerated storage testing of freeze-dried Pseudomonas fluorescens BTP1, BB2 and PI9 strains

Influence of Freezing and Freeze Drying on Intracellular Enzymatic Activity and Autolytic Properties of Some Lactic Acid Bacterial Strains

Kinetic study of Lactococcus lactis strains (SLT6 and SLT10) growth on papain-hydrolysed whey

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