The shielded region was in fluid communication with the cavity so that thawed material may flow from the cavity into the shielded region. Even if microwave-thawing systems have not been commercially successful but microwave-tempering systems have found successful applications in the meat and dairy industry Bialod et al. A vacuum-heat thawing system operates by transferring the heat of condensing steam under vacuum to the frozen product.
Theoretically, a condensing vapor in the presence of a minimum amount of a non-condensable gas can achieve a surface film heat transfer coefficient far higher than that achieved in water thawing.
The principle of operation is that when steam is generated under vacuum, the vapor temperature will correspond to its equivalent vapor pressure. The steam will condense onto any cooler surface such as a frozen product.
The benefits of latent heat transfer cooking without any problems which would occur at atmospheric pressure. Thawing cycles are very rapid with thin materials, enabling high daily throughputs to be achieved. The advantage of a high h-value is increasing less marked as material thickness, and beef quarters or 25 kg meat blocks require thawing times permitting no more than one cycle per day.
The cost of largest capacity units tones can restrict its application. The frozen product is continuously tumbled with vacuum tumble thawing systems while steam under vacuum condenses on the exposed surfaces of the food. Very fast thawing is claimed to be obtained with small bulk-frozen individual products.
Heat is produced in the frozen foodstuff during radio frequency thawing because of dielectric losses when a product is subjected to an alternating electric field. A homogeneous regular slab is placed between parallel electrodes in an idealized case of radio frequency heating without any heat exchanging.
When an alternating electromotive force emf is applied the electrodes thawing and tempering using microwave processing the resulting field in the slab is uniform, so the energy and the resultant temperature rise is identical in all parts of the food.
Foodstuffs are not generally in the shape of perfect parallelepipeds; for example, frozen meat consists of at least two components fat and lean. During loading, frozen meats pick up heat from the surroundings, the surface temperature rises and the dielectric system is not presented with the uniform temperature distribution required for even heating.
To overcome runaway heating with slabs of frozen pork bellies, workers have tried coating the electrodes with lard, placing the bellies in oil, water and saline baths and wrapping the meat in cheesecloth soaked in saline solution. Only the last treatment was successful but even that was not deemed practical.
An industrial system was installed to thaw frozen blocks of boned-out poultry in the late s. The continuous plant had a throughput of kg per hour with four It was claimed that the process reduced thawing time from 3 to 4 days to less than 2 hours and cut weight loss from 7 to 0.
Microwave or radio frequency cooking are newer methods that have been introduced to the meat industry. Roasts cooked by microwave took less time to reach endpoint temperatures in comparison with conventional methods. Meat cooked with microwaves does not have typical browned surface associated with other methods of cooking because of short cooking time. Radio frequency as a volumetric form of heating is another rapid cooking alternative in which heat is generated within the product, which reduces cooking times and could potentially lead to a more uniform heating.
Microwave oven cooking tends to retain higher amounts of vitamins such as retinol, thiamin, and riboflavin compared with earth-oven-cooked meat. The difference in vitamin retention could be due to a higher cooking temperature of earth-oven cooking compared with microwave cooking Welke et al.
In cooking process, the contractile proteins of meat myosin and actin will denature and the connective tissue collagen under goes to solubilize. MW heating can solubilize more collagen percentage of hydroxyproline than does boiling. In general, MW-cooked meat and poultry have higher cooking losses than those cooked by conventional methods Moody et al.
Cooking losses, evaporation and drip losses were greater for steaks cooked in MW convection ovens compared with those cooked in forced air convection or conventional ovens, though they found no difference in juiciness, tenderness, beef flavor, or external color of the steaks.
Evaporative losses were higher for oven dry-roasted beef than for MW- convection roasts, which were higher than MW roasted samples. Drip losses were highest for MW, followed by oven roasted, then by MW-convection roasted samples. Although Instron shear values did not differ, oven dry-roasted samples were judged as tender by taste panelists.
Lean meat cook yield was lower for MW-cooked rib eye roasts while it was the same for round and chuck roasts, whether cooked conventionally or in the MW.
Tenderness, softness, natural flavor and tenderness shear force were unaffected. MW-cooked rib eye roasts were browner and less juicy. Visual color and tenderness improved for meat products cooked in the MW oven. There were no differences in drip loss of MW-cooked chops, though evaporative and total losses were lower than for broiling. Flavor scores were highest for broiled chops and did not differ due to MW power level. Chops cooked at low MW power were juiciest and tenderness varied inversely with cooking rate.
Overall acceptability was lowest for chops cooked at high MW power level. Textural analysis showed greater peak forces for hot air oven-cooked products compared to MW-cooked products. MW cooking time was shorter and produced more uniform heating, though flavor was better in hot air oven-cooked products.
Cooking time of chicken breasts increase with decreasing power level, but cooking losses are not affected. It was reported that convection-MW-cooked chicken was more tender, juicy and acceptable than MW-cooked chicken even if its flavor intensity was similar Hines et al. Exposure of pre-rigor broiler muscle to MW energy can decrease glycogen metabolism but it has no effect on ATP retention and is not improve tenderness.
When meat is cooked in the MW, addition of fluids and other ingredients, and cooking from the frozen state, appear to improve the overall outcome.
Curing of buffalo meat using a polyphosphate solution may increase pH from 5. When cooking started from the frozen state, roasts cooked by MW on low power were comparable to those conventionally cooked in sensory quality. Roasts cooked from the frozen state by MW on high power had lower palatability scores except flavor and higher shear values.
While MW cooking resulted in lower fat contents, and higher water-holding capacity, TBA value and cook yield than conventional oven cooking. Visually, MW-heated beef may appear to be unevenly cooked. MW-thawed and cooked roasts and steaks may be redder in the interior, and lighter and more yellow on the exterior, than their broiled counterparts.
The irregular shape of many whole meat cuts results in significantly non-uniform heating. In addition, bone reflects MW, causing overheating in the regions adjacent to the bone Moody et al. Thermal insulation at the faces of the slab increases this variation. MW is used primarily for reheating precooked meat products, making cook loss even more problematic. Because fluid losses appear to be the primary roadblock in producing precooked, reheatable meat products, adding fluid enhancement has been evaluated in an effort to produce a juicy product.
However, flavor may suffer during MW reheating. Reheating of precooked frozen turkey in MW and conventional ovens tends to create stale, aldehyde-like aroma.
Meaty-brothy flavor and aroma were more intense in MW-reheated meat. MW-reheated light meat was flat or bland flavored, less juicy and higher in moisture content than conventionally reheated meat. MW cooking had no effect on chicken flavor or aroma, though MW reheating resulted in less warmed-over flavor than conventional reheating.
TBA analyses showed that multiple reheating of dark turkey meat using MW energy retarded lipid oxidation, including that caused by NaCl 2. MW reheating did not influence warmed-over aroma or flavor or TBA values of cooked stored roast beef. Cooking fresh meat in a microwave can represent a challenge since the cool air surrounding the meat results in lack of browning.
While the meat heats up inside, there is mass transfer from the interior to the outside, resulting in a tough, dry and flavourless product. Ingredient selection can target these problems, such as a salt-based coating to attract microwave energy to the surface of the meat along with a colouring agent, a water binding ingredient such as starch to reduce moisture loss and an enzyme to retain tenderness.
Flavours can be added for overall improvements. In general it is recommended to keep the salt concentration as low as possible to improve the penetration depth and slow the heating at the surface while providing more uniform heating and avoiding thermal runaway.
On the other hand, the addition of salt may be recommended in some cases as it can increase the heating rate at the surface for particular applications Schiffmann, ; Taki, ; Schiffmann, Quality control methods and microstructural evaluation were employed to study the qualitative parameters of meat and meat products. Microscopical techniques are used to characterize meat structure.
Optical microscopy achieved the observation of fat globules distribution and protein gel in emulsion-type buffalo meat sausages. It revealed that caseinate and modified whey form distinct dairy protein gel regions within meat batters, and this could explain their ability to enhance the textural properties of the meat batters compared with the other dairy proteins Krishnan and Sharma ; Barbut, Scanning electron microscopy SEM and environmental scanning electron microscopy ESEM have been used for the examination of living and fresh botanical samples including fungal mycelium and cross sections of stems from different plant sources.
ESEM has been known as one of the most interesting new developments in the field of electron microscopy. A number of studies have demonstrated the use of ESEM for hydrated biological samples. Some research compared unprocessed ESEM specimens and samples prepared by conventional methods. Much research has been done on the study of wool fiber.
Processes for industrial wool commence with sheep breeding and conclude with the study of finished fabric. Investigations in many of these processes can be largely enhanced using ESEM microscopes and techniques. In this study ESEM has been applied to study the microstructure of goat semimembranosus muscle, using raw muscle as a control and comparing it to different heat treatments including conventional and microwave heating.
Scanning electron microscopy was useful to show structure differences in low-fat sausages. The environmental scanning electron microscopy ESEM is capable of examine specimens in a gaseous environmental saturated with water vapor and higher resolution micrographs have been illustrated at the presence of gas. The environmental scanning microscope has been described as a scanning electron microscopy technique to retain a minimum water vapor pressure of at least pa in the chamber specimen.
ESEM creates the possibility of testing practically any sample which is wet Fig. Diagrammatic representation of a two-stage differential pumping system for an ESEM. Source: Danilatos, The two main parts of the instrument include an electron gun chamber or electron opticsolumn and specimen chamber.
The gun chamber is located at the top part of instrument and provides a flow of electrons by heating a tungsten filament, lanthanum hexaboride filament or field emission source. The specimen chamber is capable of working at a very poor vacuum unlike any other types of ESEM which require high vacuum. Therefore this specimen will not dry and ESEM is used to observe specimens in the fresh state.
Some important advantages have been shown for the gas around the samples in the specimen chamber. Accumulation of charge on insulating samples can be recognized as a basic advantage for this technique. This phenomenon occurs by ionization of the gases inside the specimen chamber and nowadays much work has been done on it. The gas itself can be employed as a detector in the microscope system which is another advantage for ESEM Parsons et al. The result shows bundles of muscle fiber in raw SM muscle that is parallel to each other Fig.
The collagen fibers surrounding the muscle fiber are not clear in some Figures, but in Fig. In order to observe collagen more clearly than before, Miller stain was used. This technique increased contrast by increasing the conductivity of the material Miller, Structure of SM muscle using Miller stain. Collagen network appears bright c: collagen, mf: muscle fiber. As shown in Fig. Cross section of SM muscle has been shown in Fig.
There is also the possibility which might occur from electron beam on the sample if the operating system is not clearly set and adjusted prior to imaging. If you are told to put something in a Microwave oven for 70 seconds, it is just a tried and tested method of getting the food to the correct internal temperature.
You can't compare it to a standard oven. This chart displays Watts with the corresponding temperature. I hope this helps. I assume you mean what temperature would your food be after microwaving it? It depends on the food. A microwave isn't getting hot like an oven does. It shoots microwaves at your food which causes the food to heat up a certain amount. The amount it heats up depends a lot on its water content, mass, etc. A microwave is going to transmit a fixed amount of energy to your food in a given time frame.
This energy will be converted to heat. However since its a fixed amount of energy it depends on what is receiving the energy that determines how much its heated up. A pound steak will rise in temperature much less than the 1 pound steak because there is more of the pound steak to heat up. I've been using the following basic guidelines, but I do feel the need to gather more accurate information so will be following up with scientific method.
I've had good luck with this. My microwave was manufactured to be Watts, but I'm not sure that is helping me so I'll need to be checking it's actual output with 1 liter of water nuked on high and then measuring the temperature between 70F and after result. Then multiplying that by 35 should get acceptably near the wattage. At least, as we used to say in the military, "close enough for government work".
A recipe that says "70 seconds on high in a Watt microwave" wants exactly that: put it in a W microwave for 70 seconds, at full power setting.
The recipe author already worried about how hot or done the food is supposed to get from these settings; if you adjust the recipe including doubling or halving , or use a weaker or stronger microwave, you have to estimate how much to adjust the cooking time.
Sign up to join this community. The best answers are voted up and rise to the top. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Learn more. What temperature is 'High' in a watt microwave?
Ask Question. Asked 6 years, 10 months ago. How hot does a microwave get? Oh sorry! Before asking this question I must have asked how often are you going to use a microwave rather than an oven each day? I guess N number of times. Microwave is an essential appliance in every kitchen and sometimes it becomes necessary to be aware about your product.
If you are well informed about your product, it would be helpful to you in every way. My curiosity starts after using my product couple of times. A microwave will be your best friend especially if you are heating last night leftovers. Actually microwave takes couple of second or minutes to reheat the food as compare to other conventional methods.
The best part about a microwave oven is that it is a Time Saver. Suppose you have to leave for a meeting or an event and you are short of time, a microwave can boil water, tea, or milk or even heat a bowl of some food stuff so quickly.
But of course, if you are cooking something complex you need to know about the Microwave Temperature. Microwave is a perfect gadget in your kitchen to save your valuable time that you can devote to other household chores it is an electric device performs function of cooking and heating with electromagnetic radiation.
0コメント