scholarly journals Impact of cultivation strategy, freeze-drying process, and storage conditions on survival, membrane integrity, and inactivation kinetics of Bifidobacterium longum

2020 ◽  
Vol 65 (6) ◽  
pp. 1039-1050
Author(s):  
Regina Haindl ◽  
Alexandra Neumayr ◽  
Anika Frey ◽  
Ulrich Kulozik
Keyword(s):  
Freeze Drying ◽  
Bifidobacterium Longum ◽  
Membrane Integrity ◽  
Storage Conditions ◽  
Inactivation Kinetics ◽  
Whole Process ◽  
Cultivation Strategy ◽  
And Storage ◽  
Kinetics Of ◽  
Shelf Temperature

AbstractBifidobacterium longum, one of the main microorganisms in the human gut, is used as an adjunct to lactic acid starter cultures or sold as a probiotic product. Therefore, Bifidobacterium longum cell suspensions get freeze-dried with protective additives to prevent activity losses. To date, investigations covering growth and inactivation kinetics of Bifidobacterium longum during the whole process (cultivation, drying, and storage) have been lacking. In this study, the effect of cultivation conditions and shelf temperature as well as the influence of protectants (maltodextrin, glucitol, trehalose) at various concentrations on cell survival during freeze-drying was assessed. Drying was followed by a storage at + 4 °C and + 20 °C for 70 days to evaluate inactivation kinetics. The impact of the different factors was assessed by measuring surival rate and residual moisture content at various points of time over the whole process. In parallel cell membrane integrity and glass transition were determined to reveal inactivation effects. Cultivation strategy had a strong influence on survival with a huge potential for process improvement. A pH of 6.0 at the growth optimum of the strain provides better conditions regarding cell survival after drying than free acidification (non-regulated pH conditions). During the drying step, membrane leakage due to the removal of water is the main reason for the inactivation in this process step. In this study, the highest survival of 49% was obtained with cells dried at + 35 °C shelf temperature with an addition of maltodextrin (75% bacterial dry matter, w/w). The results show that Bifidobacterium longum cells are mostly inactivated during drying, whereas storage conditions at + 4 °C with an addition of 75% BDM maltodextrin relative to bacterial dry mass prevent cell loss completely.

scholarly journals Optimising storage conditions and processing of sheep urine for nitrogen cycle and gaseous emission measurements from urine patches

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Alice F. Charteris ◽  
Karina A. Marsden ◽  
Jess R. Evans ◽  
Harry A. Barrat ◽  
Nadine Loick ◽  
...  
Keyword(s):  
Freeze Drying ◽  
Storage Conditions ◽  
Chemical Components ◽  
Gaseous Emissions ◽  
Gaseous Emission ◽  
Grazing Systems ◽  
And Storage ◽  
Sheep Urine ◽  
Country Specific

AbstractIn grazing systems, urine patches deposited by livestock are hotspots of nutrient cycling and the most important source of nitrous oxide (N2O) emissions. Studies of the effects of urine deposition, including, for example, the determination of country-specific N2O emission factors, require natural urine for use in experiments and face challenges obtaining urine of the same composition, but of differing concentrations. Yet, few studies have explored the importance of storage conditions and processing of ruminant urine for use in subsequent gaseous emission experiments. We conducted three experiments with sheep urine to determine optimal storage conditions and whether partial freeze-drying could be used to concentrate the urine, while maintaining the constituent profile and the subsequent urine-derived gaseous emission response once applied to soil. We concluded that filtering of urine prior to storage, and storage at − 20 °C best maintains the nitrogen-containing constituent profile of sheep urine samples. In addition, based on the 14 urine chemical components determined in this study, partial lyophilisation of sheep urine to a concentrate represents a suitable approach to maintain the constituent profile at a higher overall concentration and does not alter sheep urine-derived soil gaseous emissions.

scholarly journals Growth kinetics of Salmonella Typhimurium and Listeria monocytogenes in buffalo milk under different processing and storage conditions

2021 ◽  
Vol 51 (11) ◽  
Author(s):  
Joelson Sousa Lima ◽  
Ana Paula Presley Oliveira Sampaio ◽  
Mylla Christy da Silva Dufossé ◽  
Paula Fernanda Morais de Sousa ◽  
Josyane Brasil da Silva ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Salmonella Typhimurium ◽  
Growth Kinetics ◽  
Storage Conditions ◽  
Buffalo Milk ◽  
Production Chain ◽  
Pasteurized Milk ◽  
Processing And Storage ◽  
And Storage ◽  
Kinetics Of

ABSTRACT: Buffalo milk is rich in nutrients and can serve as a substrate for the proliferation of microorganisms. Thus, the objective of the present study was to evaluate the growth kinetics of Salmonella Typhimurium and Listeria monocytogenes in buffalo milk under different processing and storage conditions. Samples of raw and pasteurized milk were inoculated with 1 CFU of each bacterium, separately and together, per 25 mL. After contamination, samples were stored at 8 °C or 37 °C, and bacterial counts were performed at 24, 48, and 168 h. In addition, the accompanying microbiota growth, pH, and the effect of these variables on the growth kinetics of microorganisms were monitored. The pathogens tested were able to proliferate under most conditions tested, reaching high titers throughout the experimental period. At 37 °C, there was a decrease in pH and an increase in the accompanying microbiota that interfered with the microbial growth curve. It was also observed that pasteurized milk subjected to 8 °C provided better conditions for the multiplication of bacteria. Therefore, it was concluded that care throughout the production chain, storage, and commercialization of milk must be adopted to guarantee the microbiological safety of this food.

Preservation and Storage Mechanisms for Raw Milk Samples for Use in Milk-Recording Schemes

1996 ◽  
Vol 59 (2) ◽  
pp. 151-154 ◽  
Author(s):  
HUMBERTO G. MONARDES ◽  
ROBERT K. MOORE ◽  
BRIAN CORRIGAN ◽  
YVON RIOUX
Keyword(s):  
Cell Count ◽  
Somatic Cell Count ◽  
Potassium Dichromate ◽  
Dairy Herd ◽  
Raw Milk ◽  
Storage Conditions ◽  
Sample Storage ◽  
Milk Samples ◽  
Whole Process ◽  
And Storage

This study, carried out by the Quebec Dairy Herd Analysis Service, compares (during summer conditions in Quebec) the performance of three types of preservatives for raw milk under four different systems of sample storage: no refrigeration, refrigeration at the laboratory only, refrigeration during transport and at the lab, and complete refrigeration from sampling at the farm to analysis. The objective was to determine the best preservative and storage conditions for protecting milk components during transportation and storage of raw milk samples collected at the farm and sent to a central testing lab for analysis. Milk samples were analyzed at day 3 and at day 7 after sampling to observe the effect of aging. A total of 12,480 samples were collected during the trial. The components studied were percentage of fat and protein and somatic cell count (SCC). In general, samples preserved with bronopol (2-bromo-2-nitropropane-1,3-diol and 2-bromo-2-nitropropanol) in liquid or in microtab tended to give higher readings for fat and protein contents than samples preserved with potassium dichromate. Significantly lower fat values were observed in 7-day-old samples compared to 3-day-old samples. Fat depression was more accentuated in nonrefrigerated samples. Under current methods of handling raw milk samples, refrigeration during the whole process of sampling, transportation, and until analysis, seems an ideal to attain to avoid significant reductions of fat values.

scholarly journals Protective Effects of Tropical Fruit Processing Coproducts on Probiotic Lactobacillus Strains during Freeze-Drying and Storage

2020 ◽  
Vol 8 (1) ◽  
pp. 96 ◽  
Author(s):  
Caroliny Mesquita Araújo ◽  
Karoliny Brito Sampaio ◽  
Francisca Nayara Dantas Duarte Menezes ◽  
Erika Tayse da Cruz Almeida ◽  
Marcos dos Santos Lima ◽  
...  
Keyword(s):  
Membrane Potential ◽  
Freeze Drying ◽  
Room Temperature ◽  
Membrane Integrity ◽  
Added Value ◽  
Protective Effects ◽  
Tropical Fruit ◽  
Freeze Dried ◽  
Fruit Processing ◽  
And Storage

This study evaluated the protective effects of coproducts from agroindustrial processing of the tropical fruits acerola (Malpighia glabra L., ACE), cashew (Anacardium occidentale L., CAS), and guava (Psidium guayaba L., GUA) on the probiotics Lactobacillus paracasei L-10, Lactobacillus casei L-26, and Lactobacillus acidophilus LA-05 during freeze-drying and storage. The occurrence of damage to membrane integrity, membrane potential, and efflux activity of Lactobacillus cells after freeze-drying was evaluated by flow cytometry, and viable counts were measured immediately after freeze-drying and during 90 days of storage under refrigerated or room temperature conditions. Probiotic strains freeze-dried without substrate had the overall highest count reductions (0.5 ± 0.1 to 2.9 ± 0.3 log cycles) after freeze-drying. Probiotics freeze-dried with fruit processing coproducts had small cell subpopulations with damaged efflux activity and membrane potential. Average counts of probiotics freeze-dried with ACE, CAS, or GUA after 90 days of storage under refrigerated or room temperature were in the range of 4.2 ± 0.1 to 5.3 ± 0.2 and 2.6 ± 0.3 to 4.9 ± 0.2 log CFU/g, respectively, which were higher than those observed for strains freeze-dried without substrate. The greatest protective effects on freeze-dried probiotics were overall presented by ACE. These results revealed that ACE, CAS, and GUA can exert protective effects and increase the stability of probiotic lactobacilli during freeze-drying and storage, in addition to supporting a possible added-value destination for these agroindustrial coproducts as vehicles for probiotics and for the development of novel functional foods.

scholarly journals Flow-cytometric assessment of damages to Acetobacter senegalensis during freeze-drying process and storage

2013 ◽  
Vol 2 (1s) ◽  
pp. 10 ◽  
Author(s):  
Rasoul Shafiei ◽  
Frank Delvigne ◽  
Phillipe Thonart
Keyword(s):  
Freeze Drying ◽  
Storage Temperature ◽  
Culture Media ◽  
Cell Envelope ◽  
Storage Conditions ◽  
Cell Multiplication ◽  
Drying Process ◽  
Log Reduction ◽  
Downstream Processes ◽  
And Storage

Downstream processes have great influences on bacterial starter production. Different modifications occur to cellular compounds during freeze-drying process and storage of bacterial starters. Consequently, viability and culturability (multiplication capacity) undergo some changes. In this study, the effects of freeze-drying process and storage conditions were examined on cell envelope integrity, respiration and culturability of <em>Acetobacter senegalensis</em>. Freezing of cells protected with mannitol (20% w/w) did not affect cell multiplication and respiration considerably; however, 19% of cells showed compromised cell envelope after freezing. After drying, 1.96&times;10<sup>11</sup> CFU/g were enumerated, indicating that about 34% of the cells could survive and keep their culturability. Drying of the cells induced further leakage in cell envelope and finally 81% of cells appeared as injured ones; however, 87% of the dried cells maintained their respiration capacity. Storage temperature had significant effect on cell multiplication ability; higher storage temperature (35&deg;C) caused 8.59-log reduction in cell culturability after nine-month period of storage. Collapse of cell envelop integrity and respiration was observed at 35&deg;C. At lower storage temperature (4&deg;C), the culturability decreased about one-log reduction after nine months. Cell envelope integrity was subjected to minor changes during a period of nine month-storage at 4&deg;C whereas a heterogeneous population of cells with different respiration capacity emerged at 4&deg;C. These results indicate that a major part of cells undergone drying process and storage entered into viable but non-culturable state. In addition, usage of different culture media didn&rsquo;t improve resuscitation. Besides, it seems that sub-lethal damages to cell envelope caused uptake of propidium iodide, however these kinds of injuries could not impress cell multiplications and respiration.

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