Collapse temperature comes up often in conversation and rarely with the context attached. Here we lay out the basics in order, then work through the practical considerations.
Last reviewed on 2025-12-29. Where a claim depends on a specific study, the study is described rather than over-claimed.
The low pressure used during drying allows water vapor to move from the ice surface to a cold condenser. Energy supplied as heat drives sublimation but must stay below the collapse temperature of the frozen matrix. If the product becomes too warm, the frozen structure may soften or melt, reducing pore formation and slowing drying. Formulations often include bulking agents, stabilizers, or buffers to support a rigid cake. The final moisture content depends on formulation, freezing rate, and the length of secondary drying.
Freeze-drying is distinct from simple evaporation and from spray drying. Evaporation removes water at temperatures above freezing, while spray drying rapidly dries droplets in a heated gas stream. Lyophilization avoids high temperatures, which can be useful for heat-sensitive materials such as proteins, vaccines, and some foods. The porous cake produced by sublimation dissolves or rehydrates more quickly than a dense dried mass. Not all materials tolerate freezing or the pH shifts that can occur as solutes concentrate during ice formation.
The physics of freeze-drying couples heat transfer, mass transfer, and phase change. Heat supplied through the shelf must reach the sublimation front without melting the ice or degrading the product. Water vapor then travels through the already dried layer and leaves the chamber, where low pressure and cold traps keep it from returning. The dried layer acts as a resistance to vapor flow, so drying rate changes as the front recedes. Open questions remain about how pore structure and formulation heterogeneity affect drying uniformity at larger scales.
Lyophilization removes water from a frozen material by sublimation under reduced pressure. The process begins with freezing, which converts liquid water into ice and concentrates dissolved solids. Primary drying then lowers chamber pressure so ice changes directly into vapor without passing through a liquid phase. Secondary drying raises the shelf temperature to remove bound water that remains after ice sublimation. The result is a dry, porous structure that can be reconstituted later.
Formulation composition influences whether freeze-drying produces an intact cake or a collapsed mass. Excipients such as sugars and polymers can raise the collapse temperature and provide bulk during drying. The critical temperature for primary drying is often the collapse temperature or the glass transition temperature of the maximally concentrated phase. If the product temperature exceeds this threshold, the frozen matrix may soften and lose structure. Established practice therefore links shelf temperature and chamber pressure to the formulation's thermal properties.
| Property | Value | Notes |
|---|---|---|
| Primary phase change | Sublimation | Ice changes directly to vapor under reduced pressure |
| Typical chamber pressure | 0.01–0.5 mbar (1–50 Pa) | Below the triple point of water; product-specific |
| Typical product temperature during primary drying | −40 °C to −10 °C | Kept below collapse temperature |
| Typical residual moisture | 0.5–3% w/w | Target range varies by formulation and use |
| Common synonyms | Freeze-drying; lyophilisation | Lyophilization is the US spelling |
A typical cycle begins with freezing, which fixes the material into a solid and determines ice crystal size. Primary drying then raises heat under vacuum so ice sublimes, often near or below the collapse temperature of the formulation. Secondary drying removes bound water that remains after ice is gone, usually by gently warming the product. Each stage balances heat input against pressure to avoid melting or structural damage. Temperature probes and pressure sensors guide the transition between stages.
In practice, lyophilization is slower and more energy intensive than simple drying. Cycle times can range from hours to several days depending on load, container, and formulation. Amorphous materials may require excipients that help preserve structure during freezing and drying. The method is widely used for biological materials, pharmaceuticals, and foods where heat drying would cause unacceptable change. Open questions remain about scaling cycles between laboratory and production equipment, and this gap affects technology transfer.
Lyophilization is a dehydration technique in which a product is frozen and the solvent is removed under reduced pressure. The low pressure allows ice to sublimate directly into vapor without passing through a bulk liquid phase. This differs from conventional drying, where heat drives evaporation and can damage heat-sensitive structures. The process is used for biological materials, pharmaceutical formulations, and some foods. Its main advantage is preservation of porous structure and rapid reconstitution.
Freezing is the first stage and sets the ice structure that later becomes the pore network. The formulation is cooled below its freezing point, often with a controlled ramp, and solutes concentrate as ice forms. Primary drying then lowers chamber pressure and supplies heat to sublime the ice. The product temperature must stay below its collapse or eutectic temperature to prevent structural loss. Secondary drying raises the temperature modestly to remove bound water and achieve a low residual moisture.
=== Exercise === Early experimental evidence that skeletal muscle contraction induces vascular endothelial growth factor (VEGF) expression came from studies using electrically stimulated muscle. In a rat model, Hang et al. (1995) demonstrated that electrically stimulated skeletal muscle exhibited significant upregulation of VEGF expression, establishing skeletal muscle fibers as an active source of angiogenic signaling. This work preceded later exercise-training studies and contributed to the understanding of VEGF as a contraction-responsive factor involved in skeletal muscle angiogenesis.
=== Even- vs odd-chained fatty acids === Most naturally occurring fatty acids are even-chained, e.g. stearic (C18:0) and oleic (C18:1), meaning they are composed of an even number of carbon atoms; odd-chained fatty acids (OCFA) also occur, albeit far less frequently. The most common OCFA are the saturated C15 and C17 derivatives, pentadecanoic acid and heptadecanoic acid respectively, which are found in dairy products. On a molecular level, OCFAs are biosynthesized and metabolized slightly differently from the even-chained relatives.
El Bulli 1983–1993 (with Juli Soler and Albert Adrià) El Bulli: el sabor del Mediterráneo, 1993, ISBN 84-7596-415-X Los secretos de El Bulli, 1997, ISBN 84-487-1000-2 El Bulli 1994–1997 (with Juli Soler and Albert Adrià) Cocinar en 10 minutos con Ferran Adrià, 1998, ISBN 84-605-7628-0 Celebrar el milenio con Arzak y Adrià (with Juan Mari Arzak), 1999, ISBN 84-8307-246-7 El Bulli 1998–2002 (with Juli Soler and Albert Adrià), Conran Octopus, 2003, ISBN 1-84091-346-0; Ecco, 2005, ISBN 0-06-081757-7 El Bulli 2003–2004 (with Juli Soler and Albert Adrià), Ecco, 2006, ISBN 0-06-114668-4 El Bulli 2005 A Day at El Bulli 2008 FOOD for thought THOUGHT for food (El Bulli y Ferran Adrià), 2009 ACTAR Editorial, ISBN 978-84-96954-68-7 The Family Meal: Home Cooking with Ferran Adrià 2011 Phaidon, ISBN 978-0-7148-6253-8 In October 2008, Ferran Adrià published A Day At El Bulli along with Juli Soler, and Albert Adrià. The book describes 24-hours at the El Bulli restaurant, with images, commentary, photographs and 30 recipes. Most of the recipes included are complex and require many out-of-the ordinary kitchen appliances, such as a Pacojet, freeze-dryer, liquid nitrogen tank, candyfloss machine and Perspex molds.
A 2023 review found that men tend to be diagnosed with type 2 diabetes at a younger age and lower BMI, and that women with the condition have a higher relative risk of cardiovascular disease and death than men (although absolute cardiovascular mortality remains higher in men), yet women, particularly younger women, are less likely to receive guideline-recommended cardiovascular risk reduction. Racial and ethnic minorities are disproportionately affected with higher prevalence of diabetes compared to non-minority individuals. While US adults overall have a 40% chance of developing type 2 diabetes, Hispanic/Latino adults chance is more than 50%. African Americans also are much more likely to be diagnosed with diabetes compared to White Americans. Asians have increased risk of diabetes as diabetes can develop at lower BMI due to differences in visceral fat compared to other races. For Asians, diabetes can develop at a younger age and lower body fat compared to other groups. Additionally, diabetes is highly underreported in Asian American people, as 1 in 3 cases are undiagnosed compared to the average 1 in 5 for the nation. People with diabetes who have neuropathic symptoms such as numbness or tingling in feet or hands are twice as likely to be unemployed as those without the symptoms. In 2010, diabetes-related emergency room (ER) visit rates in the United States were higher among people from the lowest income communities (526 per 10,000 population) than from the highest income communities (236 per 10,000 population).
For the second consecutive year, the AFL's opening round was spread across two weekends. Due to concern over one-sided matches, each of the top four teams from 2012 (Sydney, Hawthorn, Adelaide and Collingwood) played each of the bottom four teams (the Western Bulldogs, Melbourne, Gold Coast and Greater Western Sydney) only once each – except that Sydney played local rival Greater Western Sydney twice, and that the Western Bulldogs played Adelaide twice. None of the bottom five teams from 2012 (Western Bulldogs, Port Adelaide, Melbourne, Gold Coast and Greater Western Sydney) featured in a Friday night match during the home-and-away season. This is due to the AFL's policy of awarding Friday night matches only to teams that perform consistently throughout the season. This season was the last in which AFL football was played at AAMI Stadium, with both Adelaide and Port Adelaide moving to a redeveloped Adelaide Oval from the 2014 season. Match starting times are local.
Sources: en.wikipedia.org
Tadalafil, sold under the brand name Cialis among others, is a medication used to treat erectile dysfunction, benign prostatic hyperplasia, and pulmonary arterial hypertension. It is taken by mouth. Onset is typically within half an hour and the duration is up to 36 hours. Common side effects include headache, muscle pain, flushing, and nausea. Caution is advised in those with cardiovascular disease. Rare but serious side effects include a prolonged erection that can lead to damage to the penis, vision problems, and hearing loss. Tadalafil is not recommended in people taking nitrovasodilators such as nitroglycerin, as this may result in a serious drop in blood pressure. Tadalafil is a PDE5 inhibitor which increases blood flow to the penis. It also dilates blood vessels in the lungs, which lowers the pulmonary artery pressure. Tadalafil was approved for medical use in the United States in 2003. It is available as a generic medication. In 2022, it was the 172nd most commonly prescribed medication in the United States, with more than 3 million prescriptions.
Cooperatives also play a great part in banking. Cooperative banks in India serve both the rural and urban societies. Just like the sugar companies, these institutions serve as the power base for local politicians.
Hygiene, e.g. measured by number of micro-organisms per mL of finished product. Energy efficiency measured e.g. by "tonnes of steam per ton of sugar produced". Minimization of waste, measured e.g. by "percentage of peeling loss during the peeling of potatoes". Labour used, measured e.g. by "number of working hours per ton of finished product". Minimization of cleaning stops measured e.g. by "number of hours between cleaning stops".
== See also == Adipose tissue Appetite Basal metabolic rate Energy homeostasis Glucagon Glycemic index Glycemic load Hyperinsulinemia Insulin sensitivity Insulin Ketogenic diet Leptin Lipogenesis Low-carbohydrate diet Low-glycemic index diet Metabolic Syndrome Obesity Refined carbohydrates Set point theory Sugar Ultra-processed food
Sources: en.wikipedia.org
=== Equipment === The gauge of the needle used can range from 25 gauge to 27 gauge, while the length can vary between 1⁄2-inch to 5⁄8-inch for injections using a syringe and needle. For subcutaneous injections delivered using devices such as injector pens, the needle used may be as thin as 34 gauge (commonly 30–32 gauge), and as short as 3.5 mm (commonly 3.5 mm to 5 mm). Subcutaneous injections can also be delivered via a pump system which uses a cannula inserted under the skin. The specific needle size/length, as well as appropriateness of a device such as a pen or pump, is based on the characteristics of a person's skin layers.
Dean Robinson (born 9 September 1974) is an Australian fitness coach who has worked with a variety of both AFL and NRL clubs. Better known as The Weapon, Robinson is notable for his intense training methods which were criticised following a spate of soft-tissue injuries at Essendon in the second half of the 2012 AFL season. Prior to his work as a professional fitness coach, Robinson showed a passion for rodeo. Acting the position of both a steer wrestler and a rodeo clown, Robinson proved a versatile competitor and went all the way to the World Steer Wrestling Association titles in 1997. He also spent several years training other rodeo athletes, before later branching out into additional sports. Before his association with a long string of clubs, Robinson worked at the NSW Institute of Sport. His subsequent transition into the NRL was sparked by his brother Trent Robinson, who had been employed in a variety of coaching roles at several clubs. Beginning in 2005, Robinson worked with the Manly Sea Eagles. Spending two years at the club, Robinson implemented a far more scientific approach to training than was previously in place. Robinson’s contribution to the club’s improved performance did not go unnoticed, and in 2006 AFL clubs also began to express interest in his services. This soon culminated in the Geelong Football Club hiring him for the 2007 season. Robinson left Geelong to join the new Gold Coast Football Club in their inaugural season. After a year there, he moved back to Melbourne and began working for the Essendon Football Club.
=== Status epilepticus === Status epilepticus may be defined as seizure activity lasting beyond five minutes and needing anticonvulsant medication. Several guidelines recommend the use of propofol for the treatment of refractory status epilepticus.
Sources: en.wikipedia.org
Lyophilization relies on sublimation, so water moves from solid ice to vapor without becoming liquid. The material is frozen, pressure is reduced, and controlled heat is supplied. Vapor is captured on a cold condenser, leaving a dry porous solid.
The process has three main stages: freezing, primary drying, and secondary drying. Freezing sets the ice structure, primary drying removes free ice, and secondary drying removes bound water. Each stage uses specific temperature, pressure, and time settings.
No, it is a drying method rather than a sterilization method. Removing water can limit microbial growth, but it does not reliably kill microorganisms. Sterility must come from separate steps such as filtration, heat treatment, or aseptic processing.
Primary drying removes ice by sublimation at low pressure and low shelf temperature. Secondary drying removes bound water by raising the shelf temperature, often under the same vacuum. The two stages differ in the water state being removed.