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1,3-Dichloropropene, chemical formula C3H4Cl2, is a clear to straw-coloured liquid with a sharp, sweet, irritating odour.  1,3-Dichloropropene dissolves in water and evaporates easily. It is a by-product in the chlorination of propene to make allyl chloride 
PAH substances can be carcinogenic but are used in many consumer products. German institute estimates that it is possible to minimise the PAH content to below 0.2 mg/kg. The German BfR institute for risk assessment estimates that it is possible to minimise the PAH content in consumer products to below 0.2 mg/kg. Many polycyclic aromatic hydrocarbons, or PAHs, are carcinogenic and safe dose levels cannot be derived for carcinogenic substance mixtures. PAHs are used in many consumer products with long-term or repeated skin contact. BfR estimates that it is technically feasible to minimise the PAH content to 0.2 below mg/kg in all common rubber materials, elastomers and plastics. Lowering the levels in plastic and rubber parts of products will further reduce consumers’ exposure to PAHs. The BfR evaluation has been reached in connection with their work on development of German criteria for the GS certification mark for product safety.
Pizza is one of the world’s most popular foods. In the US, 350 slices are eaten every second, while 40% of Americans eat pizza at least once a week. There’s a reason why pizza is so popular. Humans are drawn to foods that are fatty and sweet and rich and complex. Pizza has all of these components. Cheese is fatty, meat toppings tend to be rich, and the sauce is sweet. Pizza toppings are also packed with a compound called glutamate, which can be found in the tomatoes, cheese, pepperoni, and sausage. When glutamate hits our tongues, it tells our brains to get excited — and to crave more of it. This compound actually causes our mouths to water in anticipation of the next bite. Then there are the combinations of ingredients. Cheese and tomato sauce are like a perfect marriage. On their own, they taste pretty good. But according to culinary scientists, they contain flavour compounds that taste even better when eaten together. Another quality of pizza that makes it so delicious: Its ingredients become brown while cooking in the oven. Foods turn brown and crispy when we cook them because of two chemical reactions. The first is called caramelisation, which happens when the sugars in a food become brown. Most foods contain at least some sugar; once foods are between 230 and 320 degrees, their sugars begin to turn brown. Caramel is made from several thousand compounds, making it one of the most complex food products. On a pizza, ingredients like onions and tomatoes become caramelised during baking, making them rich and sweet and flavourful. That brown and crispy crust is also the result of the dough caramelising. While the meat and cheese on your pizza also get brown, this is due to a different process called the “Maillard reaction,” which is named after French chemist Louis-Camille Maillard. The Maillard reaction occurs when the amino acids in high-protein foods like cheese and pepperoni react with the sugars in those foods when heated. Pepperonis that become crispy with curled edges, and cheese that browns and bubbles, are examples of the Maillard reaction at work. With bread, cheese, and tomato sauce as its base, pizza might seem like a simple food. It isn’t. And now, the next time you’re about to devour a slice, you’ll be able to appreciate all of the elements of pizza that excite our brains, thrill our taste buds, and cause our mouths to water.