3 edition of Freezing and thawing microbes found in the catalog.
Freezing and thawing microbes
P. H. Calcott
Bibliography: p. 64-68.
|Statement||P. H. Calcott.|
|Series||Patterns of progress : Microbiology series ; PP/M/14|
|LC Classifications||QR69.F7 C34|
|The Physical Object|
|Pagination||68 p. :|
|Number of Pages||68|
|LC Control Number||79305881|
Hi, why do we have to freeze the cells slowly, and thaw them rapidly?-backlash-QUOTE (backlash @ Dec 26 , PM) Hi, why do we have to freeze the cells slowly, and thaw them rapidly? "For bacteria it's important to freeze quickly. That's because when freezig slowly, ice cristals may form. Freeze the glycerol stock tube at °C. The stock is now stable for years, as long as it is kept at °C. Subsequent freeze and thaw cycles reduce shelf life. To recover bacteria from your glycerol stock, open the tube and use a sterile loop, toothpick or pipette tip to scrape some of the frozen bacteria .
Cooked pork has no business thawing on the counter. Concerns About Re-Freezing. There’s actually a valid reason behind the myth that frozen meat can’t be thawed and refrozen. That’s because bacteria can start growing on your meat when you thaw it. And if you thaw and refreeze and thaw again, the theory is that you have even more bacteria. Thawing Meat. Meat conducts heat very poorly. Smaller meat cuts will freeze and thaw much faster than large pieces. Thawing is a much slower process than freezing and is best done in a refrigerator. The process would be faster if performed at higher temperature but that would create favorable conditions for the growth of bacteria.
For example, freezing and thawing meat more than one time might cause color and odor changes, moisture loss, and increased oxidation of its fat and protein (3, 4, 5, 6). Freeze-thaw—you know it’s bad for your samples, don’t you? While working in the lab, you have most likely heard someone say ‘aliquot your protein/cells/DNA/RNA to avoid too many freeze-thaw cycles.’ But do you actually understand why? You probably thought that avoiding freeze-thaw cycles had something to do with damaging cell structure as well as proteins or DNA/RNA—and you .
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Additional Physical Format: Online version: Calcott, P.H. Freezing and thawing microbes. Shildon [Eng.]: Meadonfield Press, © (OCoLC) Actually, there are many other known and yet unknown processes occurring during freezing that may injure bacteria.
So low temperatures can be hazardous for microbes in many different ways. According to a study, in certain situations, repeated freezing and thawing (when done properly) may kill more bacteria than freezing in itself. Most proteins withstand freezing and thawing without adverse effects but many cellular functions, dependent on protein complexes, may be affected; enzyme systems are particularly apt to change.
When freezing microbes, it is important to realize that damage may be caused by freezing, storing and thawing. Protection must be considered for each by: HOLLANDER DH, NELL EE. Improved preservation of Treponema pallidum and other bacteria by freezing with glycerol.
Appl Microbiol. May; 2 (3)– [PMC free article] MAJOR CP, McDOUGAL JD, HARRISON AP., Jr The effect of the initial cell concentration upon survival of Freezing and thawing microbes book at C.
J Bacteriol. Mar; 69 (3)– [PMC free article] Cited by: I’m not an expert in biology, but I had to nerd out about this question because I see people say wildly different things.
That means someone has to be wrong. The Common Wisdom What’s the common wisdom. I just Googled “Does freezing kill bacteria?”. Calcott PH () Freezing and thawing microbes. Meadow Field, Durham Google Scholar Calcott P, Wood D, Anderson L () Freezing and thawing induced curing of drug-resistance plasmids from bacteria.
HARRI-4 4' t I ' Figure 1. Survival of Lactobacillus fermenti in brothto asingle freezing andtoasecondfreezing after storage intervals of 1 week, 4 weeks, and 8 weeks. A'S Figure S. Survival of bacteria to successive freezings after storage intervals of 1 week. A, Lactobacillusfermentiinbroth.B,Escherichiacoli in water.
within the tube during the course of the experi. Yes, they do. For a look at survival of Lactobacillus and other bacterial species after multiple freeze/thaw cycles, check out Harrison (below). The awesome hand-drawn graphs show that many bacteria survive after being frozen for 11 weeks.
There's also a figure on the following page showing that many bacteria also survive after multiple freeze-thaw cycles, but I won't include that page.
slowing the movement of molecules, causing microbes to enter a dormant stage. Freezing preserves food for extended periods because it prevents the growth of microorganisms that cause both food spoilage and foodborne illness. Freezing to 0 °F or below inactivates any microbes -- bacteria, yeasts, and molds -- present in food.
Quick freezing and thawing lead to less inactivation of microorganisms than does slow freezing and thawing. Quick freezing is highly desirable for reasons of product quality. According to Lorentzen /13/, the freezing and thawing times, but also the temperature profile of the product, depend on the enthalpy reduction, thickness, geometry.
Effect of high-temperature short-time pasteurization, freezing and thawing, and constant freezing on the survival of Yersinia enterocolitica in milk. Food Protect.
– Freezing to 0 °F inactivates any microbes — bacteria, yeasts and molds — present in food. Once thawed, however, these microbes can again become active, multiplying under the right conditions to levels that can lead to foodborne illness.
Repeated freezing and thawing may cause cell damage to the meat, releasing nutrients, making them more available to bacteria. Repeated thawing increases the time that the meat is at a temperature that bacteria can grow.
Freezing and thawing food In general, frozen foods have an excellent safety record – it is extremely rare for a foodborne illness to be traced back to a frozen food. Freezing preserves food by either stopping microbes (bacteria, fungi etc) from multiplying or halting the foods own enzyme activity that would otherwise cause the food to rot.
However, once the ice begins to thaw, the bacteria can "wake" back up. The researchers also found that the freezing and thawing process does kill about 90% of a virus each time it's thawed.
Another recent study of ice cubes shows they are loaded with bacteria. These bacteria aren't killed by the freezing process, but they may not be able to grow. Freeze/Thaw has plenty of laugh out loud moments, but its all pinned on an intriguing and quite feasible near-apocalyptic scenario.
The story is packed with great characters, page turning action and cool tech. This is relatable, accessible sci-fi, and though his madcap writing personality still shines through now and then, Freeze/Thaw proves /5(22).
Exposed rock is subject to various processes that act to erode and weather away the surface. These processes, such as freeze-thaw weathering, help to break apart exposed rock, and ultimately shape the landscape.
The impact of freezing and thawing on rock is most prominent in mountain environments, such as the French. Microbes. Soil freeze-thaw cycles caused an approximate twofold increase in both soil and ion-exchange resin extractable inorganic N in the organic soil during the period following snowmelt through commencement of leaf-out (Sorensen et al.,Sanders-DeMott et al., b).
3 Modelling of Freezing Processes 51 Q. Tuan Pham 4 Specifying and Selecting Refrigeration and Freezer Plant 81 Andy Pearson 5 Emerging and Novel Freezing Processes Kostadin Fikiin 6 Freezing of Meat Steve James 7 Freezing of Fish Ola M.
Magnussen, Anne K. Hemmingsen, Vidar Hardarsson, Tom S. Nordtvedt, Trygve M. Eikevik. This work was undertaken in an attempt to find out what fundamental changes occur in bacteria as the result of freezing. Aqueous suspensions of young cultures-usually 20 hours old-were prepared, and small quantities were frozen rapidly with solid carbon dioxide at °C.
Viable counts were made before and after freezing. The results varied with different organisms. Wet books should be left frozen longest before air drying or vacuum freeze dried. As the books thaw, assess the degree of wetness remaining.
If the books are slightly wet or damp, proceed as in step 4. If the books are still wet, as the books thaw, interleave every 16 pages or so with paper towels or clean, unprinted newsprint.The greatest weight losses during the freezing, thawing and cooking were registered at slow freezing procedures (freezing rate of 022 cm/h and 029 cm/h), when the meat was tougher and less soft.
Freezing Food Doesn't Kill E. Coli And Other Germs: The Salt An outbreak of E. coli in frozen pizza, cheesesteaks, and other foods makes it clear: .