TKF Science Writing

Melamine is an important compound in organic chemistry. It is used in many different industries due to its versatility in different environments (temperature, acidity, etc.). There is a dark side to this compound which lead to massive infant sickness and death in China. Researchers are finding that long term complications are being seen in infants who consume melamine contaminated milk powder.

Melamine is described as a white, solid-like structure that is semi-soluble in water. It has a chemical formula of C3N3(NH2)3. In industry, it is primarily used to make a resin which is heat and fire tolerant. Whiteboards, floor tiles, kitchenware, fire retardant fabrics, formica countertops, and commercial filters are produced from the resin. The resin is produced by mixing urea with formaldehyde. When this combo is heated, it is easily moldable into desired shapes making this compound a versatile starting material for various products.

In 2008, China had a serious problem with melamine contamination in infant milk formulations. The chemical appeared to have been added to the milk to increase its protein content. Chinese food companies have been adding this compound to wheat flour. Usually the nitrogen content of a food is the marker used to measure the protein content. High protein foods are in high demand given the world’s protein demand and so economically, the strategy made sense.

The effects that the addition of melamine would have on health was not studied well enough. According to researchers, melamine, in high doses, can cause kidney stones and kidney failure in small animals. Because melamine is a crystalline structure, the urea in the body won’t effectively dissolve it all. The undissolved portions accumulate in the kidneys which can lead to kidney stones and kidney failure. Approximately 300,000 infants were sickened by melamine in China.

According to a study by the World Health Organization in October of 2008, melamine, when combined with cyanuric acid (also found in infant formula), forms crystals in the kidneys. Many companies and laboratories are now working on ways to detect melamine tainted products.

Since milk is an essential part of the human diet, especially in infants, the FDA guided its efforts to try and isolate the melamine-cyanuric acid complex. Milk is 88% water with the remaining 12% consisting of proteins, fats, and sugars. The additional vitamins and minerals such as calcium and potassium make it easy for melamine to disguise itself when contaminated. Scientists would first “clean-up” the milk sample by removing unwanted items. In theory, this should leave the analyte of interest (melamine). Scientists found that, by lowering or raising the pH level, the toxic melamine-cyanuric acid complex can be broken. This complex is held together by hydrogen bonds, which are relatively weak so by changing the system (acid or base) that this compound sits in, allows researchers to isolate the analyte. Once the sample is cleaned up, a technique called chromatography, or more precisely, high performance liquid chromatography (HPLC) allows researchers to purify the compound as much as possible.

According to the FDA website, it has contacted infant formula production companies and found that there is no melamine threat to infant formulas produced in the United States. These companies are reporting that they do not use imported formulas from China. For further information, you can log on to the FDA website and search for melamine which will bring you to a list of products that the FDA advises consumers not to ingest due to a possible melamine contamination.

History and Origin

Gouda is a semi-soft cheese made primarily from cow’s milk and is named from the town of its origin in the South Holland region of the Netherlands.  In researching the origin of Gouda, some say that it dates back to 1697.  Farmers from the region would bring their cheese to the market and eventually, the cheese adopted the name from which it came.  

How Gouda is Made

The cow’s milk is cultured and heated until the curd is separated from the whey.  Curd is the part of milk that coagulates as seen when putting sour milk into a cup of coffee.  The whey or milk plasma is the liquid portion leftover after the curd has been strained.  The curd is then “washed” by adding hot water.  This separates out more whey from the curd.  The resulting mixture is pressed into circular moulds and soaked in a brine solution.  Eventually, a rind will form.  After soaking, the cheese is dried then coated to prevent dehydration and then allowed to ripen.

Taste

A very complex tasting cheese, Gouda meshes salty, sweet, sour, bitter, and umami (meaty or savory) flavors all in one tasty bite.  It also exhibits a fifth and not well-known flavor profile described as having mouthfullness, thickness, and a complex body.  This flabor profile is due to the presence of what are called Kokumi compounds.

Kokumi Sensation

Termed by the Japanese, Kokumi compounds generate the Kokumi sensation, which is a Japanese word used to describe deliciousness.  More succintly, it describes the continuity and roundness of a particular food.  Scientists in Munich, Germany, in a recent journal article from the Journal of Agricultural and Food Chemistry were seeking to unlock the flavor secrets of these compounds as it relates to Gouda cheese.

To start, the scientists chose two Gouda subjects of different ripeness; a 44-week and a 4-week cheese .  Their goal was to understand and apply biological principles that give rise to Gouda’s unique flavors by separating components and attempting to recombine them synthetically.  The results of the synthetically re-combined product was measured against the original components in natural Gouda.  They did this by focusing on the small-molecule metabolite profiles recognized by our taste sensors.

Senses

The four sensory tastes (bitterness, sweetness, sourness, and umami) were recognized previously in different studies of cheese.  Calcium and magnesium chloride were found to give rise to bitterness along with amino acids.  Lactic acid and hydrogen phosphate brought out a sour taste.  Sodium chloride and sodium phosphate were culpable for the salty sensation.  Lastly, Unami, the meaty or savory sensation was a result of monosodium L-glutamate and sodium lactate.

Results

The scientists found that tasters preferred and noticed a more pronounced mouthfullness, thickness, and a complex body in the natural 44-week subject more than the artificial re-combinant.  This lead scientists to believe that the Kokumi compounds and subsequent sensation are generated through the ripening process and that re-creating that taste may be a difficult endeavour.  In any event, to get the full Gouda flavor, for now, your best bet is to visit your local cheese shop.