Science Facts

How Sugar Gets White Colour? – Decolorization

White Sugar

Sugar is removed from the plant and washed to remove the naturally present molasses and other plant materials. It is not white, moved by bleach. The real sugar in your pantry comes from sugar beets and sugarcane plants. Sugar beets are related to red beets but are white and much larger than their cousin. The sugar is stored in their root. Sugar cane looks similar to bamboo and stores the sugar in its stalk.

When sugar is initially extracted from the plants, it has a golden color because of the nonsugar materials attached to and within the sugar crystals. The sugar is then purified by removing the plant fibers and molasses and resulting in white sugar crystals. Sugar crystals are the same granulated sugar you buy at the grocery store. From the plant to the product, no bleach is used to make sugar white.

How sugar gets white colour?

Sugar can be found on food labels under many different names like rice syrup, barley malt, high-fructose corn syrup, or dextrose. All these are nothing but just other names of the same sugar. White sugar also goes through a similar round of refining as white flour. It is obtained from sugar cane or sugar beets.

After extracting the juice from these raw materials, the roughage or fibrous part is discarded. The juice is then thickened and crystallized, and at this point, it is known as raw sugar. Raw sugar is darker in color as it contains molasses. The raw sugar is further refined to get the white crystals of sugar, which eventually make their way to kitchens.

The process of refining includes two steps:

Step 1 – Removal of molasses

This step lightens the color of the sugar. Over the years, molasses has been reported to have many beneficial health properties. It has a plethora of vitamins and minerals, including iron, manganese, and selenium. In fact, these days, molasses is sold separately as a dietary supplement in the market.

Step 2 – Decolouring

The 2nd step of refining sugar is decoloring. After removing molasses, the sugar crystals are treated with another decolorization round to lighten their color further. What remains is pure white crystals of sugar.

Sugar obtained in the sugar manufacturing industry is generally brown or golden in color, also known as raw sugar. To obtain the white-colored refined sugar, it is necessary to treat it with some additional processes. In many sugar manufacturing industry refining is done along with the sugar production process. But in some industries, it is completely done after sugar manufacturing. So the steps involved in sugar refining involves:

  • Collection of raw sugar.
  • Affination.
  • Melting.
  • Defecation or clarification.
  • Filtration.
  • Decolorization.
  • Evaporation.
  • Crystallization.

Affination: During refining, raw sugar is taken for affination. Raw sugar contains many impurities, which are added mainly on the surface. In affination, raw sugar is mingled with one saturated syrup to soften the adhering film of molasses.

Melting: After affination, the next step is melting sugar. The affinated sugar is dissolved with hot condensate to obtain a liquid syrup of 72-degree Brix at 75 degrees celsius prior to defecation.

Defecation: After melting, defecation or clarification is done. It helps reduce almost 40 percent colorants in this process. Defecation is of two types: Carbonatation and phosphatation.

  • Carbonatation is also called carbonation. Melted sugar is treated with lime that is calcium hydroxide into this mixture. Carbon dioxide gas is pumped reaction between calcium hydroxide and carbon dioxide forms calcium carbonate. Calcium carbonate removes the impurities, and we obtain the purified sugar syrup.
  • In phosphatation, melted sugar is treated with lime and phosphoric acid. The reaction between lime and phosphoric acid forms calcium phosphate precipitates, removing the impurities from the sugar syrup and obtaining the purified sugar syrup.

Filtration: After clarification, sugar syrup is filtered by using various filters like pre-coat vacuum filters, pre-coat pressure filters, deep bed multimedia filters, or a combination of these to produce a filtered syrup.

Decolorization: After filtration, the filtered syrup is treated further for decolorization. Several techniques can be used for removing color from sugar syrup. The most common technique is activated carbon in the form of powder or granules apart from that polymeric media like synthetic iron exchange resins or absorbent. Resins or bone char can also be used for the decolorization of sugar syrup.

Evaporation: After filtration and decolorization, sugar syrup has a 68 to 72 degrees Brix concentration. But for crystallization, supersaturation of syrup is necessary, which can be attained at 80 degrees Brix. To concentrate sugar syrup, evaporation is done using multiple effect evaporators.

Crystallization: After evaporation, crystallization is done under reduced pressure of 75 to 90 kilopascal and 60 to 70-degree Celsius temperature conditions. Many times, crystallization is initiated by adding a small quantity of sucrose. The crystals thus formed are grown under automatically controlled conditions until the desired final grain size is achieved. The process of centrifugation separates the sugar crystals.

Frequently asked questions

Is white sugar is good for health?

Over the last fifty years or so, sugar consumption and the percentage of obesity in the world have increased hand in hand. There is enough evidence to believe that sugar and processed foods containing them are directly linked to obesity, chronic diseases like type-II diabetes, or even heart diseases.

The problem with sugar or processed foods is that they lack the presence of any fiber. As a result, they are absorbed very quickly by the body and instantly raise blood sugar and insulin levels.

Although sugary foods provide you with calories, they do not give you a feeling of satiety or fullness. It doesn’t register to the brain that you have eaten anything at all. As a result, the hunger is back in no time.

A study found that people who had sugary drinks before their meals ate more than people who did not have sugary drinks. This showed that consumption of processed foods containing sugar might increase your intake of regular meals. Not just fiber, sugar does not contain any nutrients whatsoever. It is the reason sugar is also known as a source of empty calories.

Is brown sugar is better than white sugar?

A common belief is that brown sugar is better than white sugar. However, this is only a misconception. Brown sugar is made by adding a small percentage of molasses back into white sugar. Therefore, although brown sugar contains slightly higher nutrients than white sugar, the percentage is small to give any real health benefits.

Brown sugar contains approximately 5% molasses versus 95% sugar granules. In contrast, white sugar has been stripped of that molasses. Contrary to popular belief, most brown sugar on the market is not somehow purer or more natural, or less processed than white sugar. It is more processed than white sugar because it adds molasses back to the white sugar at the final production stage.

With that said, molasses does contain the minerals calcium, potassium, iron, and magnesium. But they are in such trace amounts that consuming brown sugar the cost drastically outweighs any benefit you’re getting from those minerals. At the end of the day, sugar is sugar, whether it’s brown whether it’s white.

It is most difficult to give up sugar in all the white foods, as sugar is present in almost everything, from those cookies to flavored yogurts to soda cans. While completely refraining from these food products might not seem possible, moderation is the key to sugar as well. Be vigilant of how often you consume these food products and try to make careful choices daily.

How many teaspoons of sugar is recommended per day?

Based on evidence that over-consumption of sugar is linked with cases of obesity, overweight, and dental caries, the world health organization has recommended adults and children reduce their daily intake of sugar to less than 10% of the total energy intake. That is about 25 g of sugar or 6 teaspoons of sugar per day.


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