Hot air oven

Last updated
Hot air oven Hot air oven.jpg
Hot air oven

Hot air ovens are electrical devices which use dry heat to sterilize. They were originally developed by Louis Pasteur, [1] and are essentially the same as fan ovens used for cooking food. Generally, they use a thermostat to control the temperature. Their double walled insulation keeps the heat in and conserves energy, the inner layer being a poor conductor and outer layer being metallic. There is also an air filled space in between to aid insulation. An air circulating fan helps in uniform distribution of the heat. These are fitted with the adjustable wire mesh plated trays or aluminium trays and may have an on/off rocker switch, as well as indicators and controls for temperature and holding time. The capacities of these ovens vary. Power supply needs vary from country to country, depending on the voltage and frequency (hertz) used. Temperature sensitive tapes or biological indicators using bacterial spores can be used as controls, to test for the efficacy of the device during use.

Contents

Advantages and disadvantages

They do not require water and there is not much pressure build up within the oven, unlike an autoclave, making them safer to work with. This also makes them more suitable to be used in a laboratory environment. They are much smaller than autoclaves but can still be as effective. They can be more rapid than an autoclave and higher temperatures can be reached compared to other means. As they use dry heat instead of moist heat, some pathogens like prions, may not be killed by them every time, based on the principle of thermal inactivation by oxidation.[ citation needed ]

Usage

A complete cycle involves heating the oven to the required temperature, maintaining that temperature for the proper time interval for that temperature, turning the machine off and cooling the articles in the closed oven till they reach room temperature. The standard settings for a hot air oven are:

....plus the time required to preheat the chamber before beginning the sterilization cycle. If the door is opened before time, heat escapes and the process becomes incomplete. Thus the cycle must be properly repeated all over.

These are widely used to sterilize articles that can withstand high temperatures and not get burnt, like glassware and powders. Linen gets burnt and surgical sharps lose their sharpness.

Related Research Articles

<span class="mw-page-title-main">Kiln</span> Furnace for clay products

A kiln is a thermally insulated chamber, a type of oven, that produces temperatures sufficient to complete some process, such as hardening, drying, or chemical changes. Kilns have been used for millennia to turn objects made from clay into pottery, tiles and bricks. Various industries use rotary kilns for pyroprocessing and to transform many other materials.

<span class="mw-page-title-main">Endospore</span> Protective structure formed by bacteria

An endospore is a dormant, tough, and non-reproductive structure produced by some bacteria in the phylum Bacillota. The name "endospore" is suggestive of a spore or seed-like form, but it is not a true spore. It is a stripped-down, dormant form to which the bacterium can reduce itself. Endospore formation is usually triggered by a lack of nutrients, and usually occurs in gram-positive bacteria. In endospore formation, the bacterium divides within its cell wall, and one side then engulfs the other. Endospores enable bacteria to lie dormant for extended periods, even centuries. There are many reports of spores remaining viable over 10,000 years, and revival of spores millions of years old has been claimed. There is one report of viable spores of Bacillus marismortui in salt crystals approximately 25 million years old. When the environment becomes more favorable, the endospore can reactivate itself into a vegetative state. Most types of bacteria cannot change to the endospore form. Examples of bacterial species that can form endospores include Bacillus cereus, Bacillus anthracis, Bacillus thuringiensis, Clostridium botulinum, and Clostridium tetani. Endospore formation is not found among Archaea.

<span class="mw-page-title-main">Pressure cooking</span> Cooking food under high-pressure steam

Pressure cooking is the process of cooking food with the use of high pressure steam and water or a water-based liquid, inside a sealed vessel called a pressure cooker; the high pressure limits boiling and creates higher temperatures not possible at lower pressures which allow food to be cooked much faster than at normal pressure.

<span class="mw-page-title-main">Microwave oven</span> Kitchen cooking appliance

A microwave oven or simply microwave is an electric oven that heats and cooks food by exposing it to electromagnetic radiation in the microwave frequency range. This induces polar molecules in the food to vibrate and produce thermal energy in a process known as dielectric heating. Microwave ovens heat foods quickly and efficiently because excitation is fairly uniform in the outer 25–38 mm(1–1.5 inches) of a homogeneous, high-water-content food item.

<span class="mw-page-title-main">Autoclave</span> Temperature and pressure instrument

An autoclave is a machine used to carry out industrial and scientific processes requiring elevated temperature and pressure in relation to ambient pressure and/or temperature. Autoclaves are used before surgical procedures to perform sterilization and in the chemical industry to cure coatings and vulcanize rubber and for hydrothermal synthesis. Industrial autoclaves are used in industrial applications, especially in the manufacturing of composites.

<span class="mw-page-title-main">Sterilization (microbiology)</span> Process that eliminates all biological agents on an object or in a volume

Sterilization refers to any process that removes, kills, or deactivates all forms of life and other biological agents present in or on a specific surface, object, or fluid. Sterilization can be achieved through various means, including heat, chemicals, irradiation, high pressure, and filtration. Sterilization is distinct from disinfection, sanitization, and pasteurization, in that those methods reduce rather than eliminate all forms of life and biological agents present. After sterilization, an object is referred to as being sterile or aseptic.

<span class="mw-page-title-main">Oven</span> Enclosed chamber for heating objects

An oven is a tool which is used to expose materials to a hot environment. Ovens contain a hollow chamber and provide a means of heating the chamber in a controlled way. In use since antiquity, they have been used to accomplish a wide variety of tasks requiring controlled heating. Because they are used for a variety of purposes, there are many different types of ovens. These types differ depending on their intended purpose and based upon how they generate heat.

<span class="mw-page-title-main">Convection oven</span> Appliance that heats food

A convection oven is an oven that has fans to circulate air around food to create an evenly heated environment. The increased air circulation causes a fan-assisted oven to cook food faster than a conventional non-fan oven, which relies only on natural convection to circulate the hot air. Fan-assisted convection ovens are commonly used for baking as well as non-food, industrial applications. Small countertop convection ovens for household use are often marketed as air fryers.

Infection prevention and control is the discipline concerned with preventing healthcare-associated infections; a practical rather than academic sub-discipline of epidemiology. In Northern Europe, infection prevention and control is expanded from healthcare into a component in public health, known as "infection protection". It is an essential part of the infrastructure of health care. Infection control and hospital epidemiology are akin to public health practice, practiced within the confines of a particular health-care delivery system rather than directed at society as a whole.

<span class="mw-page-title-main">Wood drying</span> Also known as seasoning, which is the reduction of the moisture content of wood prior to its use

Wood drying reduces the moisture content of wood before its use. When the drying is done in a kiln, the product is known as kiln-dried timber or lumber, whereas air drying is the more traditional method.

A waste autoclave is a form of solid waste treatment that uses heat, steam and pressure of an industrial autoclave in the processing of waste. Waste autoclaves process waste either in batches or in continuous-flow processes. In batch processes, saturated steam is pumped into the autoclave at temperatures around 160 °C, or 320 °F. The steam pressure in the vessel is maintained up to 6 bars (gauge) for a period of up to 45 minutes to allow the process to fully 'cook' the waste. The autoclave process gives a very high pathogen and virus kill rate, although the fibrous products which come from the process are susceptible to bacteria and fungus as they are high in starch, cellulose and amino acids. When designed for sterilizing waste containing mostly liquids, a waste autoclave is known as an Effluent Decontamination System.

In biology, a substrate is the surface on which an organism lives. A substrate can include biotic or abiotic materials and animals. For example, encrusting algae that lives on a rock can be itself a substrate for an animal that lives on top of the algae. Inert substrates are used as growing support materials in the hydroponic cultivation of plants. In biology substrates are often activated by the nanoscopic process of substrate presentation.

Laboratory ovens are a common piece of equipment that can be found in electronics, materials processing, forensic, and research laboratories. These ovens generally provide pinpoint temperature control and uniform temperatures throughout the heating process. The following applications are some of the common uses for laboratory ovens: annealing, die-bond curing, drying or dehydrating, Polyimide baking, sterilizing, evaporating. Typical sizes are from one cubic foot to 0.9 cubic metres (32 cu ft). Some ovens can reach temperatures that are higher than 300 degrees Celsius. These temperatures are then applied from all sides of the oven to provide constant heat to sample.

<i>Kamado</i> Traditional Japanese cook stove

A kamado is a traditional Japanese wood- or charcoal-fueled cook stove.

Dry heat sterilization of an object is one of the earliest forms of sterilization practiced. It uses hot air that is either free from water vapor or has very little of it, where this moisture plays a minimal or no role in the process of sterilization.

Moist heat sterilization describes sterilization techniques that use hot water vapor as a sterilizing agent. Heating an article is one of the earliest forms of sterilization practiced. The various procedures used to perform moist heat sterilization process cause destruction of micro-organisms by denaturation of macromolecules.

<span class="mw-page-title-main">Biomedical waste</span> Waste containing infectious material

Biomedical waste or hospital waste is any kind of waste containing infectious materials generated during the treatment of humans or animals as well as during research involving biologics. It may also include waste associated with the generation of biomedical waste that visually appears to be of medical or laboratory origin, as well research laboratory waste containing biomolecules or organisms that are mainly restricted from environmental release. As detailed below, discarded sharps are considered biomedical waste whether they are contaminated or not, due to the possibility of being contaminated with blood and their propensity to cause injury when not properly contained and disposed. Biomedical waste is a type of biowaste.

<span class="mw-page-title-main">Waste converter</span>

A waste converter is a machine used for the treatment and recycling of solid and liquid refuse material. A converter is a self-contained system capable of performing the following functions: pasteurization of organic waste; sterilization of pathogenic or biohazard waste; grinding and pulverization of refuse into unrecognizable output; trash compaction; dehydration. Because of the wide variety of functions available on converters, this technology has found application in diverse waste-producing industrial segments. Hospitals, clinics, municipal waste facilities, farms, slaughterhouses, supermarkets, ports, sea vessels, and airports are the primary beneficiaries of on-site waste conversion.

<span class="mw-page-title-main">Combi steamer</span>

Combi steamers are combination ovens that expand upon standard convection ovens in that they can also generate conventional moist steam or superheated steam and are capable of shifting between cooking modes automatically during the cooking process. They can be used to simultaneously steam vegetables or potatoes quickly and gently, while also roasting or braising meat and fish, or baking bread. The appliance is fit for many culinary applications, including baking, roasting, grilling, steaming, braising, blanching and poaching. These devices are cooking appliances typically used in professional catering or food service operations. They help gastronomy-industry professionals bridge the gap between economy and menu diversity while also maintaining the desired food quality.

<span class="mw-page-title-main">Central sterile services department</span> Hospital facility

The central sterile services department (CSSD), also called sterile processing department (SPD), sterile processing, central supply department (CSD), or central supply, is an integrated place in hospitals and other health care facilities that performs sterilization and other actions on medical devices, equipment and consumables; for subsequent use by health workers in the operating theatre of the hospital and also for other aseptic procedures, e.g. catheterization, wound stitching and bandaging in a medical, surgical, maternity or paediatric ward.

References

  1. Ananthanarayan, R; Paniker, C. J. (2006). Textbook of Microbiology (7th ed.). India: Orient Blackswan. pp. 2, 25–26. ISBN   978-8125028086.