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Snap Freezing
Snap freezing (or cook-chill or blast freezing) is the process of rapid cooling of a substance for the purpose of preservation. It is widely used in the culinary and scientific industries. Scientific use Snap-freeze is a term often used in scientific papers to describe a process by which a sample is very quickly lowered to temperatures below -70 °C. This is often accomplished by submerging a sample in liquid nitrogen. This prevents water from crystallising when it forms ice, and so better preserves the structure of the sample (e.g. RNA, protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residue (biochemistry), residues. Proteins perform a vast array of functions within organisms, including Enzyme catalysis, catalysing metab ..., or live cells).{{cite journal , title=Collection, Storage, Retrieval and Distribution of Biological Materials for Research , journal=Cell Preservation Technology , date=1 March 2008 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Liquid Nitrogen
Liquid nitrogen (LN2) is nitrogen in a liquid state at cryogenics, low temperature. Liquid nitrogen has a boiling point of about . It is produced industrially by fractional distillation of liquid air. It is a colorless, mobile liquid whose viscosity is about one-tenth that of acetone (i.e. roughly one-thirtieth that of water at room temperature). Liquid nitrogen is widely used as a coolant. Physical properties The diatomic character of the N2 molecule is retained after liquefaction. The weak van der Waals interaction between the N2 molecules results in little interatomic attraction. This is the cause of nitrogen's unusually low boiling point. The temperature of liquid nitrogen can readily be reduced to its freezing point by placing it in a vacuum chamber pumped by a vacuum pump. Liquid nitrogen's efficiency as a coolant is limited by the fact that it boils immediately on contact with a warmer object, enveloping the object in an insulating layer of nitrogen gas bubbles. Thi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residue (biochemistry), residues. Proteins perform a vast array of functions within organisms, including Enzyme catalysis, catalysing metabolic reactions, DNA replication, Cell signaling, responding to stimuli, providing Cytoskeleton, structure to cells and Fibrous protein, organisms, and Intracellular transport, transporting molecules from one location to another. Proteins differ from one another primarily in their sequence of amino acids, which is dictated by the Nucleic acid sequence, nucleotide sequence of their genes, and which usually results in protein folding into a specific Protein structure, 3D structure that determines its activity. A linear chain of amino acid residues is called a polypeptide. A protein contains at least one long polypeptide. Short polypeptides, containing less than 20–30 residues, are rarely considered to be proteins and are commonly called pep ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cell (biology)
The cell is the basic structural and functional unit of all life, forms of life. Every cell consists of cytoplasm enclosed within a Cell membrane, membrane; many cells contain organelles, each with a specific function. The term comes from the Latin word meaning 'small room'. Most cells are only visible under a light microscope, microscope. Cells Abiogenesis, emerged on Earth about 4 billion years ago. All cells are capable of Self-replication, replication, protein synthesis, and cell motility, motility. Cells are broadly categorized into two types: eukaryotic cells, which possess a Cell nucleus, nucleus, and prokaryotic, prokaryotic cells, which lack a nucleus but have a nucleoid region. Prokaryotes are single-celled organisms such as bacteria, whereas eukaryotes can be either single-celled, such as amoebae, or multicellular organism, multicellular, such as some algae, plants, animals, and fungi. Eukaryotic cells contain organelles including Mitochondrion, mitochondria, which ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flash Freezing
In physics and chemistry, flash freezing is a process by which an object is rapidly frozen by subjecting an object to cryogenic temperatures, or through direct contact with liquid nitrogen at . This process is closely related to classical nucleation theory. When water freezes slowly, crystals grow from fewer nucleation sites, resulting in fewer and larger ice crystals. This damages cell walls and causes cell dehydration. When water freezes quickly, as in flash freezing, there are more nucleation sites, and more, smaller crystals. This results in much less damage to cell walls, proportional to the rate of freezing. This is why flash freezing is good for food and tissue preservation. Flash freezing is commonly applied in the food industry and is studied in atmospheric science. Impact of freezing The surface environment does not play a decisive role in the formation of ice and snow. Density fluctuations within water droplets result in the possible freezing regions covering bo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Blast Chilling
Blast chilling is a method of cooling food quickly to a low temperature that is relatively safe from bacterial growth. Bacteria multiply fastest between . By reducing the temperature of cooked food from or below within 90 minutes, the food is rendered safe for storage and later consumption. This method of preserving food is commonly used in food catering and, recently, in the preparation of "instant" foods, as it ensures the safety and the quality of the food product. The blast chiller is a cousin of the refrigerator, another appliance designed to store food between , but the blast chiller is a higher grade and more expensive appliance and is usually only found in commercial kitchens. in the UK, blast chillers are typically priced from £2,000 to £8,000 excluding value-added tax. Use of blast chillers is prescribed for the restaurants of the European Union, e.g. in the regulations 852/2004 or 853/2004.Regulation (EC) No 853/2004 of the European Parliament and of the Council of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Food Preservation
Food preservation includes processes that make food more resistant to microorganism growth and slow the redox, oxidation of fats. This slows down the decomposition and rancidification process. Food preservation may also include processes that inhibit visual deterioration, such as the enzymatic browning reaction in apples after they are cut during food preparation. By preserving food, food waste can be reduced, which is an important way to decrease production costs and increase the efficiency of food systems, improve food security and nutrition and contribute towards environmental sustainability. For instance, it can reduce the Environmental impact of agriculture, environmental impact of food production. Many processes designed to preserve food involve more than one food preservation method. Preserving fruit by turning it into jam, for example, involves boiling (to reduce the fruit's moisture content and to kill bacteria, etc.), sugaring (to prevent their re-growth) and sealing wi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
