If you suffer from acne you will be looking for an effective treatment that won't make your skin dry and flaky and that is also good value for money. As you will be using these products for quite some time you will want to find an effective product that isn't going to leave you broke! One of the most effective ingredients used in acne products is benzoyl peroxide and we'll look at two of the most popular products that contain this ingredient here.

Most people can tolerate a 2.5% benzoyl peroxide product well but before you use one you need to be aware of the side effects. If you have never used this type of product before take care that you don't use if too often at first. It is tempting to apply it frequently in the hope that more often will lead to quicker results but this is not the best way. Only apply twice a day at first until you know how your skin is reacting. Side effects include redness, itching and dryness and these are more likely to occur if you use a high concentration cream. You should start with a low concentration such as 2.5% and only go on to a higher concentration if your skin does not react to this and if you are not getting results. For most people a 2.5% is adequate to clear their acne.

Although there are more popular products that contain high concentrations of benzoyl peroxide we'll look at only those that contain a lower 2.5% of active ingredient in this article. The first one we'll consider is produced by Acne.org. It is formulated not to be drying to the skin and should be used with the program laid out on their website. Customers who used this product at Amazon gave it an overall rating of the top five stars and found it to be effective and pleasant to use. It contains no fragrance and is considerably less drying than many other benzoyl peroxide products. It can be bought for less than $20 for an 8oz bottle or in a kit with cleanser and moisturiser. For those who are new to using a benzoyl peroxide product and who have mild to moderate acne this product is recommended.

Our second product is the Proactiv Acne Treatment System which consists of a kit containing lotion, toner, cleanser and mask. The cleanser contains exfoliating beads to prepare your skin by thoroughly cleaning the pores and the toner is gentle and alcohol free with ingredients designed to soothe inflamed skin. The lotion contains 2.5% benzoyl peroxide and is formulated to be gentle, non drying and non irritating. The Proactive kit received a four star rating by customers at Amazon.

These products will be effective against acne if used as directed. Although they may take a little longer to work than the high concentration benzoyl peroxide products they are much less irritating to the skin and will be less likely to cause redness and flaky skin than products with a higher level of the active ingredient.

Find out more and see the Top Ten Best Benzoyl Peroxide Products for Acne

Scooters that are powered by electric or gas motors are becoming increasingly popular for children and teenagers and are a good choice if your child has outgrown his kick scooter but is not yet ready for a full sized motor vehicle. Some popular models such as a Razor electric scooter or a Go-Ped are readily available and come in a wide variety of models. Motorised scooters have either a gas or electric motor and vary in both initial cost and running costs so which one should you choose for your child? We'll look at both these types of motors to see some of the advantages and disadvantages so that you can choose wisely.

The main difference between them is in performance. Gas powered scooters are generally faster than electric powered models with top speed of around thirty mph. Electric scooters vary depending on the size of the motor but the maximum speed is around twenty mph for one of the more powerful (and expensive) models with cheaper ones being somewhat slower. Speed of course, is related to safety and you need to be sure a child can handle the speed before allowing him to use one. For younger children who may be getting their first powered scooter an electric model with a lower speed is much safer. As he learns to handle it responsibly he can progress to a faster model and then to a gas powered scooter with faster speeds.

Another thing to consider is how easy the scooter is to look after. A child should be expected to take care of his own things properly and a gas powered scooter may be harder for a child to look after on his own. With a gas engine maintenance is needed to check and change the oil regularly and to make sure spark plugs are clean and not corroded. This won't be easy for a young child but an older child or teenager can be expected to do this kind of maintenance. An electric motor however needs very little looking after so will be more suitable for a younger child.

Electric scooters are easier to re-charge, just plug into a power socket at night. A gas scooter will need to be taken to a local gas station to be filled up which may not be so convenient. How long do electric scooters run on one recharge? This can vary considerably depending on the size of the motor with the cheaper scooters only carrying a charge that is enough for forty minutes of continuous use. A bigger motor can be used for up to four hours between recharging. when you are looking to buy a scooter check with the manufacturer for the running time on one charge to make sure it is enough. Although four hours may not seem very long it is plenty for a child to use his scooter around the neighborhood as he won't be using it for four hours continuously.

Running costs also need to be taken into consideration as electric powered scooters are cheaper to run than gas powered models and don't need spare parts such as oil filters and spark plugs to be changed regularly. A cheaper Razor scooter with a shorter running time can be bought for under $100. if you want one that can run for four hours between re-charges expect to pay more, perhaps as much as $350. A gas powered model such as a Go-Ped will start at around $450.

In conclusion then we can say that an electric scooter will be a better buy for a younger child who can progress to a faster, gas scooter when he is older and more experienced at both riding and looking after his scooter.

See a great selection of scooters at Razor Scooters for Sale

As parents we must ensure that our children are safe when they play and one thing we should do is to make sure the toys they play with are not hazardous to them. Buying well made toys from reputable manufacturers is essential but we can't just stop there. Children can be extremely rough with their and over time toys even the most durable toys will become damaged so we need to inspect them regularly and throw out any that cannot be repaired safely.

Wooden toys, for example, are excellent for their durability but can be chewed by small children so that splinters can be a hazard. The good news is that wooden toys, unlike plastic toys, can easily be repaired by sanding down until smooth again and repainting with lead free paint.

Toys that are played with outside can become rusty and damaged and should be checked often. If they cannot be repaired throw them out before they cause an accident.

Many of us store away toys in toy boxes but we need to make sure these do not cause safety issues. Lids on toy boxes need to be fitted with safety catches so that they don't slam shut on tiny fingers or lock if a child climbs into them. Ventilation holes are also a good idea just in case a child decides to hide in one! Inspect the edges and corners to make sure they are smooth and do not have sharp places to cause damage.

Many children's toys and music players that make sounds have volume controls and it's important not to have this set too loud. Loud noise can do permanent damage to the hearing of a child especially if he uses a music player with in-ear head phones. Make sure your child knows as soon as he is old enough to understand not to use a toy or player at full volume.

Toddlers love pull toys but they can have special hazards that we must be aware of. Cords can be easily wound around a child's neck so never let him play with a pull toy without adult supervision. Some pull toys have a mechanism to automatically retract the cord and this is a good idea as long as it is working properly. If the mechanism is broken and the cord does not retract properly cutting off the cord is safer. Your child can still play with his toy by pushing it around!

For parents who have children in different age groups it is important to be aware of the hazards that toys made for older children can have for their younger siblings. Some toys have small parts that a baby or toddler may put in their mouth or even in their ears! Check the manufacturers guidelines for the appropriateness of a toy for your child's age and warn older children not to allow their younger brothers and sisters to play with their toys.

If your child has stuffed toys that contain batteries to make sounds or lights make sure they don't take them into a bath or pool as, not only will it damage the toy, but it may be hazardous for the child. Water damages the battery which can leak. All toys that contain batteries should not be exposed to water.

It is important to be aware of the safety issues that can arise with different types of toys and always be on the look out for things that can compromise our children's safety.

Read more at Cheap Toys for Sale.

Music is all around us and expresses a wide variety of moods and feelings. It can be gentle and soothing or wild and exciting but recent research has shown that, not only is it enjoyable but it can have a profound effect on young children's brains. As a baby grows pathways in the brain are laid down which become stronger as they are used. Connections formed by listening to music are developed and become much stronger the more that the child is exposed to different forms of music.

Can these connections affect the way your child thinks and processes information? Research has shown that after listening to classical music spacial reasoning can be improved temporarily because the connections made from listening to this type of music are similar to those used for spacial reasoning. Learning to play an instrument also has an effect on spatial reasoning which is longer lasting.

All types of music help to stimulate the formation of connections in the brain but classical music seems to have the most effect. This may be due to the complexity of classical music that stimulates the brain and lays down pathways that can then be used for other complex tasks.

Music also has a profound effect on our moods and can be used to lull babies to sleep or stimulate them in play. So we should expose our children to music of all types from an early age. We can play music to babies from birth and there are many musical toys available for children of all ages. When they are a little older we can begin to introduce them to musical instruments. A good place to start is with a good quality drum that is easy on parent's ears and produces a melodic sound, rather than the annoying banging of cheap drums. Remo Djembe drums are excellent quality or try a Remo drum set. Children can start to learn about rhythm and tones and have fun at the same time. Musical hand bells are also great from an early age and children can easily use them to make different melodies.

When they are a little older a 'learn to play' keyboard will be very popular. Look for one with color coded keys so that children can easily play melodies or make up their own music. There are some good quality ones available that can be bought for around $30.

Introducing music at an early age can, not only help in their development, but give them a life long love of music.
 

If you want to stay healthy and fit would it be a good idea to take an Omega 3 fatty acid supplement? These fatty acids are beneficial and many of us are not getting enough of them in our diets. What are the benefits of Omega 3 and should we be increasing our intake of this and other related fatty acids?

Omega 3 Fatty Acid Benefits

If you look at fish oil supplements you'll see a list of the fatty acids they contain. This usually includes EPA(eicosapentaenoic acid) and DHA (docosahexaenoic acid) which are beneficial for the heart and help to improve your chances of avoiding cardio-vascular disease, hardening of the arteries and heart attacks.

However, more is not always better! You also need to be careful not to take too high a dose as this can be harmful. Always make sure you keep to the recommended dose.

Omega 3 fatty acids below to the fatty acids that are poly unsaturated. These acids have been shown in clinical trials to reduce trigyceride levels in the blood and can also raise the level of high density lipo-proteins, which are the beneficial to us. Omega 3 has also been claimed to help relieve arthritis pain and to be helpful in some conditions that effect the skin. Recent research has indicated that these fatty acids may be helpful in controlling memory loss in Alzheimer’s disease and to help increase the effectiveness of the immune system.

Which foods are rich in Omega 3?

Many coldwater fish are high in these fatty acids. These include herring, anchovies, mackerel, salmon, and tuna. Other foods are spinach, kidney beans, walnuts broccoli and canola oil. Some people in the past few years have reduced their intake of coldwater fish, which is the main source of Omega 3 in our diets, partly because there have been well publicised concerns about the levels of mercury in these fish. We only need three servings a week, of about four ounces of fish in each serving, to get enough Omega 3. This is well below the level where any mercury poisoning would occur.

In addition many people are not fond of fish and may not be eating enough of the other foods that contain Omega 3 to consume enough, so an Omega 3 fatty acid supplement would be a good idea for them.

How can children benefit from Omega 3 supplements?

In a series of clinical trials at the University of South Australia children who suffered from ADHD were given an Omega 3 and Omega 6 supplement. It was found that this had a significant effect on their ADHD symptoms particularly on their behaviour and learning abilities. 40% of the children in the trial had an improvement in these areas.

Conclusion

Overall then, if you do not eat sufficient foods that contain Omega 3 fatty acids, it would be a good idea to add a daily supplement to ensure you get enough of this essential nutrient.

Image by Peter Rosbjerg

Polymers can be natural or synthetic. Some examples of natural polymers include starch, cotton and rubber but in this article I'm going to talk about synthetic polymers such as nylon, polyethene or perspex. The building blocks of polymers are called monomers which are connected together into long chains. Synthetic polymers can consist of chains of thousands or even millions of monomer units. We'll look at the types of monomers and how they are bonded together to make polymers of various kinds.

Synthetic polymers can be divided into two types, addition polymers and condensation polymers. They are formed from different types of monomers and with different bonds between them.

Addition Polymers

Addition polymers are always made with a group of organic compounds called alkenes. These all contain a double bond between two carbon atoms. Double bonds are more reactive than single bonds and can be induced to react together, given the right conditions which usually include the use of a catalyst, increased temperature and sometimes an increased pressure. Alkenes bond together in an addition reaction and form addition polymers.

An alkene - ethene

All bonds contain two electrons and the ethene molecule has a double bond between two carbon atoms. One of these bonds is more reactive than the other one and this bond breaks during the polymerisation process. The two electrons in the bond split up and end up on each of the carbon atoms. Now the electrons on adjacent ethene molecules can join together to form a bond between the two carbon atoms on different molecules thus joining the two molecules together with a single covalent bond. The electrons on the other carbon atoms can do the same thing and join up with other ethene molecules to start to form a chain. This process can continue until a huge chain is formed.

Formation of Polyethene

Formation of radicals

Naming of Addition Polymers

Polymers are named for the alkene monomer from which they are formed so, for instance a polymer made from the alkene called ethene forms the polymer polyethene (usually called more simply polythene). Other examples include polyvinylchloride (PVC) made from chloroethene which used to be called vinyl chloride, polystyrene and polytetrafluoroethylene (PTFE or Teflon).

Condensation Polymers

In this type of polymerisation, monomers are bonded together with the elimination of a molecule of water, hence the name condensation polymer. The monomers used in condensation polymerisation can be di-alcohols (containing two -OH groups), di-carboxylic acids (containing two -COOH groups) or di-amines (containing two NH₂ groups). When a polymer is made from a di-alcohol and a di-carboxylic acid an ester link is formed and the resulting polymer is a polyester as illustrated below.

Formation of condensation polymers

When a polymer is formed between a di-carboxylic acid and a di-amine a polyamide is formed. An example of a di-amide is nylon. The monomers used in this type of polymerisation must have reactive groups at both ends to allow chains to be formed.

Once the polymers have formed, further treatment is needed to produce plastics. Dyes, stabilisers, fillers and pigments are added to produce finished products. Polymers have different properties depending on the monomers used in their production and are used in various ways. Polyethene for example is used for plastic bags, mixing bowls etc. PVC is used for water pipes, floor tiles, waterproof articles and insulating materials. Nylon is used for textiles, ropes and carpets.
 

Images can make a good article into a great article and we strongly encourage all our authors to use at least one image. Word Wolf has a very special feature which allows you to easily add an image that will be resized to suit the article. It is easy to add an image. Just click on the 'image' button in the edit screen and upload your image. That's it! Your image will now appear at the top of your article in the correct size.

So now you need to find some images to add to your articles. Before we talk about sites to find images you need to know which images you can legally use. Images that are in the public domain can be freely used.
 Other images may be licensed in a number of ways.

Creative Commons Attribution ShareAlike 3.0 License

This is the most common license you will come accross and allows you to use the image under some conditions. You must provide an attribution in the form specified by the owner of the image license.

Creative Commons Attribution-Noncommercial 3.0 License

This is similar to the license above but restricts the image to non-commercial use. Word Wolf is non-commercial so you can use images bearing this license in your articles.

Attributing an Image

On many websites you can click on the creative commons license link to find the code you can use to place an attribute in your article. On Flickr you can click on the link 'Some rights reserved' next to the creative commons logo. It will take you to a page on the Creative Commons site where you can copy the code. Next you will need to add this code to your article. To do this on the source button in the editor and paste the code into your article then click on the source button again to take you back to the visual editor.

Where to Find Free Images

Wikimedia

All of the images from Wikimedia are either in the public domain or have one of the creative commons licenses. Check the license of the image you wish to use and always attribute the owner preoperly in your article.

Stock.xchng

This site has lots of free images although you'll have to register (free) to download large images. Some require you to inform the owner if you wish to use them but many are free to use without this. Images can be used on Word Wolf feeely but check with the Stock.xchng license to make sure you are following their guidelines. Be careful to only select images on the lower part of the page as the top part shows you premium images that you have to pay for.

Stock Vault

Stock vault is very similar to Stock.xchng with an identical license. As with Stock.xchng they show images that have to be paid for above the free images so scroll down to the Stock Photos section.

Every Stock Photo

Every Stock Photo lets you search for images from all of the above sites in one place. You'll have to see individual images for the license which in most cases will take you to the license page of the site hosting the images. Their advance search can be used to search for images with a specific license, so you could search for only images with a public domain license if you don't want add attributes to your article.

Flickr or Flickr Advanced Search

Many images on Flickr are free to use provided you attribute the owner properly. To find creative commons images use the advanced search button and tick the box to find images with a creative commons license.

Free Images

These images are free to use provided you credit the Free Images website and join their mailing list.

Free Digital Photos

If you use a free image from Free Digital Photos on Word Wolf, you must place a text hyperlink on that website to the photographer's portfolio page on FreeDigitalPhotos.net.

Morgue File

Despite it's rather macabre name Morgue File is a useful place to find images! They can be used freely without the need to attribute the owner.

These are just some of the places you can find images that you can freely use on your Word Wolf articles. It's easy to find images and use them in your Word Wolf articles and an image will make your article stand out from the crowd and look make it look professional.

 

Most organic compounds can be composted and the resulting material used to great benefit in your garden. Organic compounds refers to anything that comes from animals and plants and usually has a high percentage of carbon and hydrogen, plus trace amounts of other elements such as sulfur, oxygen etc.

The aim of a compost pile is to make an environment ideal for the micro-organisms that are the main decomposers of the organic material. In addition ants, worms and snails also play a part. All organic waste will decompose over time but in a compost pile you are providing the ideal conditions for these organisms to thrive, thus accelerating the process. Organic waste will contain compounds such as proteins, sugars, carbohydrates, starches, cellulose etc which are broken down at different rates. Carbohydrates are easily broken down to their constituent sugars while plant remains containing cellulose take longer.

Getting the carbon to nitrogen ratio right

For optimal conditions that encourage microbial growth it is important that the ratio of carbon to nitrogen in the compost pile is correct. The ideal ratio is around thirty parts carbon to one part nitrogen. Carbon is the energy source for the growth of the microbes, nitrogen is needed in smaller amounts for growth as it is a crucial element in enzymes, proteins and DNA. However, if you supply too much nitrogen it will be turned into ammonia (NH₃) which will make your compost pile smell! Too little nitrogen however will prevent the microbes growing at the fastest rate and slows down the decomposition.

So how do you ensure the ratio is correct? The ratio of 'green' to 'brown' compost materials is the best way to do this. Green materials are the fruit and vegetables scraps from the kitchen, coffee grounds, grass clippings etc which will be high in nitrogen. They also contain the bacteria that you need to begin the decomposition and to supply energy in the form of heat. Brown materials are high in carbon and are the woody materials such as paper, cardboard, dried autumn leaves and sawdust. You need to make the ratio of these materials 30:1 for the best conditions inside your compost pile. If you have too many autumn leaves make a seperate pile for composting into leaf mold. Don't make the mistake of only adding green waste to your bin or you'll end up with a rotting mess full of fruit flies with a horrible smell!

Composting is an aerobic process

Aerobic means 'with oxygen'. The microbes in the compost pile use oxygen when they process the material, using the carbon for both energy and as building material for their cells. They also use the nitrogen to make proteins and DNA but need much more carbon which is why you need only a small proportion of nitrogen in your bin. Other trace materials need by the organisms to grow include phosphorus, sulphur and a variety of metals such as iron, copper, and calcium in trace amounts. In order to encourage aerobic decomposition, oxygen needs to be supplied. This can be accomplished by agitating the pile with a fork or spade regularly. In aerobic respiration a lot of energy in the form of heat is produced.

The chemical equation for aerobic respiration follows:

If the supply of oxygen is inadequate anaerobic respiration (without oxygen) will result in the production of methane and volatile organic acids, ammonia and other compounds. Sulfur containing compounds such as hydrogen sulfide are also released. Contrary to popular belief methane has no smell, it's the other compounds that are also produced by the methanogens (the bacteria active in anaerobic decompostion) that give a badly aerated compost heap it's smell.

The chemical equation for anaerobic respiration follows:

Why does a compost pile become hot?

The microbes present in the green, moist materials added to the compost pile respire aerobically using up oxygen and releasing carbon dioxide. They also release a great deal of enegy in the form of heat. A compost pile can reach temperatures as high as 150F in a few days given the right conditions. Oxygen is needed to sustain this temperature which is why it is important to agitate the pile regularly or the aerobic microbes will die off and anearobic microbes take their place.

The pH of the compost pile

The pH level in the compost needs to be between about 5 and 8. In a new compost pile the digestion of the organic matter often produces some organic acids which lower the pH. This is not a bad thing however as this encourages fungi to grow which then digest the cellulose in plant materials. In a properly aerated pile the organic acids are themselves broken down. However if you don't aerate the pile adequately the pH can drop below about 5 because the organic acids begin to accumulate and this starts to restrict the activity of the aerobic microbes.

Conclusion

Chemistry in everyday life is fun to find out about! Now you know what is going on in your compost pile, why it gets hot and why it smells if you don't get it right! If you're eager to get started on your own compost pile see How To Make A Compost Heap In Your Garden

The chemistry behind fireworks started over 2000 years ago when, according to legend, the firecracker was invented when a Chinese cook mixed up charcoal, sulphur and saltpeter. He discovered that it would explode if packed into a bamboo tube and set alight. In the 9th century the Chinese invented gunpowder and produced fireworks for important events such as the Moon Festival and New Year using a combination of potassium nitrate (also called saltpeter), sulphur and charcoal.

Each of these chemicals burns in a different way. Charcoal burns slowly, potassium nitrate quickly and sulfur crackles and pops as it burns. Using different proportions of these chemicals produced various kinds of displays. They also invented rockets by placing gunpowder in a roll of paper and igniting it at one end.

Chemistry of fireworks

To start off the reaction energy must be supplied by lighting the fuse. Potassium nitrate acts as an oxidiser by providing oxygen for the charcoal or fuel to burn, sulphur helps to keep the reaction stable. Without the oxidiser the reaction would be too slow, the oxygen provided by the potassium nitrate speeds up the reaction. The three ingredients produce potassium sulphide, carbon dioxide and nitrogen which expand with the heat and provide the propelling force. In addition the reactions are exothermic, that is they produce heat, which contributes to the rate at which the gases expand and increases the explosive power of the reaction.

Fireworks were originally only able to produce yellow or white light which was emitted by heating up the gunpowder mixture. The effect can be varied to produce more glitter by increasing the amount of sulphur or a quick flash by adding more potassium nitrate. When white or yellow light is emitted in this way it is called incandescence. As a substance is heated it glows first with a red light (~480C) through bright red (~730C) to bright orange (~930C) and yellow (~1100C) then white at over 1400C. Until the late 18th century these were all the colours that could be produced in fireworks. Chlorates were produced industrially in the 19th century and allowed reds and greens to be produced in firework displays. It was only in the 20th century that purples and blues could be produced.

How does the oxidiser work?

When heated potassium nitrate releases oxygen and nitrogen but not all of the oxygen is released. Some remains bound to potassium ions.

When chlorates were manufactured industrially they began to be used in fireworks as they are better oxidisers than the nitrates. They release all their oxygen on heating so they are better oxidisers and can produce higher temperatures in the firework which allows more intense colours to be seen and a faster explosion.

However chlorates are fairly unstable so need very special care and today perchlorates are used as they are more stable but, as they also release all their oxygen, are also good oxidisers.

The chemistry of fireworks colors

Today we have fireworks that emit red, blue, green, yellow and lavender light so how is this possible? The answer lies in the way metals emit light as they burn.

Some metals and the colour of light they emit

                 Sodium               yellow
                 Barium                green
                 Strontium           red
                 Copper               blue
                 Potassium          lavender
                 Caesium             violet
                 Magnesium         brilliant white

You may have done flame tests at school to discover the identity of a metal by placing it in a flame and noting the characteristic colour that is emitted.

How do metals emit coloured light?

To find out what happens when we burn a metal we need to know something about the atoms of the metal. All atoms have a nucleus containing protons and neutrons (except hydrogen which is the lightest atom and doesn't have any neutrons). Electrons are in orbitals at various distances from the nucleus. The electrons will always occupy the lowest energy level possible, which are the ones closest to the nucleus.

When the electrons absorb energy, e.g. if they are heated, the energy allows them to jump to a higher energy level further away from the nucleus. Once in the higher energy levels they are unstable and will fall back to a lower energy level. When they do so they emit radiation in the form of light. The wavelength of the radiation emitted depends on the energy difference between the energy levels and is different for different metal atoms and for different energy levels within the same metal, so the colour of the light you see emitted will vary with the metal.

Some metals that burn brightly such as magnesium and titanium are used for both the bright light they emit and to increase the temperature of the burning compounds.

So next time you watch a firework display not only will you marvel at the wonderful colours and sounds but you will know more about how they are produced and the fascinating chemistry of fireworks!

 

We all like to eat meat that is tender and succulent rather than tough and stringy so what is the best way to tenderize meat? How tender meat is naturally depends on a number of factors including how the meat is treated after the animal is slaughtered, the type of meat and the age of the animal.

Meat has a high proportion of protein in the form of connective tissue, called collagen, which needs to be broken down before it is tender enough to eat. Collagen makes up around 30% of the protein found in animal tissues and is a major component of skin, cartilage, organs, bones and tendons.

What is collagen?

Collagen is a protein that is made from three intertwined poly-peptide chains. A poly peptide chain is a chain of amino acids bonded together to make a natural polymer. It is a stiff, strong structure that is hard to break down. Muscles that are weight bearing or used often contain larger amounts of collagen than other parts of the animal so legs and rump will be high in collagen. The age of an animal also has a bearing on the amount of collagen present which is why meat from older animals is tougher than that from younger ones.

Collagen

What ways are there to tenderize meat?

Hanging - meat can be hung after the animal is slaughtered. This loosens the muscle fibres.
Grinding and pounding - hitting the meat with a mallet is a popular way to tenderize meat, especially steak. The action of pounding on the meat loosens the muscle fibres by breaking up the connective tissue. Mincing or chopping up meat also has the same effect.

Cooking - cooking meat slowly with moist heat breaks down the collagen. However cooking also hardens the muscle fibres so a balance needs to made between gelatinising the collagen and preventing the muscles fibres from hardening. Moist cooking for around three hours is usually enough to break down the collagen but not long enough to harden muscle fibres. The exception to this is cooking some meats, like steak, that do not have a high collagen content. These types of meats are best cooked quickly with a dry heat as they will become tough if cooked slowly. Some meats can also be tenderized more easily in a pressure cooker. Gelatin is the product when collagen is broken down by heat.

Marinating - meat can be marinated in alcohol and acidic fruits or vinegar to tenderize it. Marinating is also used to add flavour to the meat. Marinating takes time for the ingredients to break down the connective tissue in the meat. Alcohol is effective but acids from vinegar or fruits works even better.

Using enzymes to tenderize meat - some foods contain enzymes that can be used to tenderize meat. Papaya (Paw-paw) contains the enzyme papain and pineapple contains bromelin both of which break down the collagen in meat. As we said earlier collagen is made up of three protein chains and these enzymes can break the bonds between the amino acids in the protein chains.

Individual amino acids in the protein are joined together with a peptide bond (coloured blue in the protein fragment pictured below). It is this bond that these enzymes break, thus fragmenting the protein chains and destroying the collagen structure.

Protein fragment showing peptide bond (in blue)

Conclusion

Chemistry in everyday life is a fascinating subject! Look around you and you can see examples of how chemistry comes into almost everything you do every day. I hope this has sparked an interest in this subject and that you will be eager to learn more.

Image Credits

Collagen by Nevit

papaya by Olegivvitby

Cast Iron Cooking by LarimdaMEMeat