More on Microwave cooking

I had mentioned yesterday that I had cooked CDs and DVDs just to see the sparkle effects on them. Do NOT try them at home. It could result in serious fire hazard or permanent damage to your microwave oven.

I just wanted to show you here how a DVD looks after sitting inside a microwave for only 5 seconds. The image below shows a normal “raw” uncooked DVD.

Observe the random pattern burnt on the surface and the colorful effects around the burn mark. In fact you will not see any dark tell-tale burnt mark on the DVD. It is all in golden hue.

Cooked DVD

Cooking in Microwave ovens

Microwave OvenThis heading might raise eyebrows as is expected.  It takes long hours of hard work to run servers and portals. Like most of you, I make do with pizzas and takeaways half the time. But the ubiquitous microwave sitting on the shelves of our office, finally induced me to spruce up some snack when I am famished. Apart from the gallons of coffee it could brew and the standard cup-of-noodles kind of snacks it could so easily deliver, it could do a whole lot of things we never imagined – at least I never even imagined.

The following is an exercise into the world of microwave cooking with a difference – we look at all aspects – technical and practical as well.

Technical View: If you are one of those who think that technology is best left to techies and nerds, skip to the practical section. Let us be practical.

Microwave ovens use magnetrons to generate electromagnetic waves at a frequency of 2450 MHz to induce heat in water, fat and sugar molecules in the food.  Magnetrons require about 600 – 700 Watts of energy to drive them. The various power settings on the control panel actually turns the magnetron on or off as per the settings. Mercifully, the power is fed to the magnetron through a simple transformer and a power diode. Do not try to open up an unit if it fails or out of curiosity. The voltage doubler capacitor may have enough power stored in it to give a lethal shock even after switching off the mains supply. The magnetron lives close to the food chamber and its supply feeds carry enough amperes to make a toast of you.  For your safety as well as all around you, opening up the internals of a microwave oven is best left in the hands of qualified service personnels. 

If the required power were derived from a chopper power supply or to use the computer parlance – switch mode power supply, the resulting harmonics would have inundated the spectrum.  Still microwave ovens emit enough low level power to swamp around the 2450 MHz frequency. Many cordless phones operating out of this frequency spectrum are not too happy sitting around in the same room with a microwave.

Practical View: This method of cooking works because of dielectric heating, which penetrates food deeper, depending upon the composition. As there is little distance between the source of heat and the food, the food is cooked faster. As a corollary, the nutrients are retained better with microwave cooking than through conventional means.Equally, there is a flip side too – the food does not get to that stage of appetizing browning or has the time to develop that delicious golden crust. Meat cooked over a slow fire laced with spices and herbs is always delicious. It is one of the reasons why microwave ovens are more used to reheat and pop corn kernels than regular cooking by many.There is one more use to which microwave ovens can be used about which many people are unaware – zapping microbes so ubiquitous in our kitchen. Our cutting board is easily contaminated with bacteria present in the meat being sliced. You will need to wash them with hot soap water after every use normally. After cleaning, splash water over them and keep them inside microwave for a couple of minutes for zapping the unseen microbes. Table linen and cloth tablemats can be sterilized inside microwaves. However, ensure that there is water on them for real results.  

Bone-dry cloth or paper wrappers sit inside with little effect on them, as there is no water molecule to fire up. But don’t put your cutleries inside a microwave as the metal implements will act as antennas to absorb the microwave energy which manifests in the form of nasty sparking. Sustained sparking and operating an empty microwave can damage the magnetron, which is the most expensive component in a microwave.

Again use utensils, wrappers, glassware and containers specifically designed for microwave use inside a microwave. Some plastics disintegrate and the resulting carcinogens may leach into the food. Another issue about the microwave is its tendency to induce super heating in some foods under certain conditions, which can result in severe burns on the user. Covered soups or liquid food can burst into droplets of boiling liquid and steam when moved or handled immediately after cooking in microwave. Always let the food stay for sometime before handling them. Eggs display a tendency to explode inside a microwave.

Really cooking in microwave ovens:

 Let us get into the meat of the matter – I mean we will see if we can make some scrumptious meal in our office microwave oven. I suggest some caveat here, as I am not so good in churning out tasty meals.  So proceed with caution.

Chicken Nugget (has no relationship to the real ones sold in market other than the name):

 Few shredded chicken pieces, marinated in a tablespoon of black soy sauce and powdered black pepper – about 200 gms

Egg white of one egg

Sesame seeds enough to coat the chicken

Method:


After marinating for a few hours, the chicken pieces can be dipped in the beaten egg white and then hauled over the bowl of sesame seeds.    Keep the chicken pieces in several layers of kitchen paper inside microwave and cook under full power for about 4 to 7 minutes. Actual time to cook may vary depending on the chicken, microwave or the power supply conditions. Check by piercing the middle of chicken piece with a fork.

Not So Practical View:


I have cooked a dud CD inside a microwave, in a bid to lower my frustration and at first sight, it emerged unscathed. But on closer inspection, I could see that the thin metal film layer had resulted in some sparking and localized heating melting the plastic surrounding it.  I should not be surprised at the results. Typically, a microwave oven’s magnetron produces about 500 watts of electromagnetic energy, which must have been concentrated in the small surface of the metal layer on the CD – vaporizing the metal. This is not recommended for the normal household microwave ovens.

Disclaimer: The above information is provided as-is and carries no warranty express or implied about the methods or techniques explained here. The author of this Blog or the site in which this appears will not be responsible for any consequence arising out of the use of this article under any circumstances. You will be advised to read the instructions of the manufacturer of the products.

 

 

 

 

 

 

Latent Semantic Analysis

Recently people in the know of things about search engines use a buzz word – LSI  – Latent Semantic Indexing. For example when you query Google for the phrase – women portal like this : ~women portal

http://www.google.com/search?num=100&hl=en&lr=&q=%7Ewomen+portal

You can see the tilde(~) before the search phrase to indicate that you want the latent semantic analysis to be turned on, Google will try to look for the logical extension of the supplied phrase – to put it in a simple manner. Actually, it is a lot more complicated than this.

One thing I like about the Internet is the way it offers level playing field for anyone whether you are a 900 lb Gorilla or a timid 6 lb Chihuahua. We have been tinkering with LSA for sometime now – about a couple of years. Our agenda is much simpler in nature – to deliver the right page from our thousands of pages of content for a given search phrase. You would have noticed in our main page and elsewhere a search box with some mumbo jumbo about Natural language navigation.

To tell you the truth with out much technicalities and hype, LSA ( Latent Semantic Analysis) is a simple behind-the-scene process by a computer program to figure out the concept behind the word phrase and identify the matching content. Most writers use different word or phrase to describe the same idea or concept. Even the most painstaking editing effort before the publication stage will not weed out the individual bias of the language to mean different things for different people. Editors can offer consistent style and language across the entire website – but can do little to bring homogeneity to the choice of words.

For those who are technically inclined this is what is called as synonymy – where many words exist to describe a singular idea. In contrast, Polyseme describes a word or phrase with multiple meanings – again a problem in our search engine approach. Some of the words people use to search might end up getting the wrong page.

Human languages are probably one of the most complicated issues to be handled by computers. Subtle nuances of the language are not so easy to quantify in objective terms. People often intuitively “arrive” at the intended meaning of the written word by the position of the words in relation to each other. Cues like modulation of the voice, emphasis placed on syllables etc, which exist in spoken words don’t exist in a written page.

The only cue left to analyze is the relative position of the words to each other and the frequency of occurrence in each article page. Most of our pages contain thousands of occurrences of common words, which receive less weight than the unique primary keyword phrases. Evidently, these ‘weighted’ phrases are factored in to our search engine along with their synonyms for classification.

To cut a long story short, we decided to use an extensive dictionary of English words to help our version of LSA. Sometimes it is really thrilling to see that our internal search engine delivers the most appropriate article for the search phrase with relative ease. On the other hand, equally it is stumped by a contrived phrase though the frequency of this occurring is relatively small.

The technology to negotiate the vast realms of human languages is still nascent and our LSA is still at beta.

To go back to the first example of the LSA concept where we used Google to  look for the semantically related words matching the phrase – women portal, you should see many occurrences of lady, woman, female and so on from the search results page. It is also in beta …

 

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