Sugar

 

Where does sugar come from?

 

The sugar we produce comes from two very diverse sources:  sugarcane is one and sugar beets the other - about 50% of U.S. consumption is derived from each source.  Let’s start our discussion with sugarcane - which was the original source of sugar for our ancestors thousands of years ago.

 

Sugarcane : Latin Name

Saccharun offucinarum

 

How does sugar grow?

 

Sugarcane is any one of several species of true tall perennial seed grasses native to tropical and subtropical regions of South Asia.  The stalks are jointed and measure 6 to 19 feet tall.  Sugarcane species have been interbred, so the major commercial cultivars are complex hybrids.  The main product of sugarcane is sucrose which is extracted and processed as raw material in human food or is fermented to produce ethanol.

 

Propagation:

 

How is sugar propagated?

 

Sugarcane produces seeds, but stem cutting is the most common and efficient propagation method. There are small buds that sprout along the length of the stalk.  Cuts are made on either side of the bud and planted in the ground.  Large growers use mechanical planters that plant the cuttings or whole stalks and cover them with soil.  Cane takes approximately 1 to 2 years to reach maturity. 

 

A stand of sugar cane can be harvested many times.  Stalks re-grow after each harvest with smaller yields after each successive harvest, so they need to be freshly re-planted after two to ten harvests.

 

Harvest:

 

How is sugarcane harvested?

 

Harvesting is done by hand or mechanically.  

 

By hand:  First the field is set on fire which burns the leaves without hurting the stalks and roots.  Then the stalks are cut with a knife or machete right above ground level.  A skilled worker can harvest approximately 1,000 lbs. of can an hour.

 

Mechanical harvesting is done by large machines that cut the cane at the base, strip the leaves and chop the stalks into regular lengths that are then dumped into a transporter following alongside the harvester.  The remainder of the plants are blown back onto the field.  A harvester cuts over 100 tons an hour.

 

Processing:

 

How is sugarcane processed?

 

Making sugar is a complicated process divided into two stages:  Milling and refining.  These are sometimes done in two separate locations or, in the case of a large processing plant, in one big facility.

 

Milling:  

 

How is sugarcane milled?

 

1. Extraction: The first step after harvest is to bring the sugarcane to a sugar mill where juice is extracted from canes by running them through a series of large roller mills that operate like the old-fashioned wringers used to squeeze water out of washed clothes a century ago.  The leftover fiber, or “bagasse”, is used to power the sugar mill and the furnaces that heat the boilers for the next step in the milling process.  

 

2.  Evaporation:

The sugar juice runs through a boiler (or series of boilers) in order to clean it of impurities.  Lime is added to settle out the dirt and the remaining  juice is reduced to a thicker syrup by boiling off the water. Mixing also stops the decay of cane sucrose into glucose and fructose. 

 

3.  Crystallization

The sugar syrup is moved to a large container where it continues to boil until conditions are right for sugar crystals to grow.  The crystallization is triggered by adding some crystals or sugar dust to initiate crystal formation.  Then the resulting mixture is poured into a centrifuge where the crystals are separated from the remaining “mother” liquid.

 

4. Drying and storage:

The crystals are then dried with hot air and moved to a storage warehouse where they await further processing or transport to a processing plant.  This sugar is still in a very raw state, dirty from storage, heavy with molasses and without the distinctive sugar taste consumers expect. 

 

Refining:  

 

How is sugarcane refined?

 

1.  Raw milled sugar is mixed with a heavy syrup and cleaned in a centrifuge.  This washes away the outer coating of the sugar crystals leaving a pure, clean crystal.

 

2.  The crystals are dissolved into a syrup and phosphoric acid and calcium hydroxide are added that further combine with impurities and float to the surface where they are skimmed off.  Carbon dioxide may be used instead of phosphoric acid to the same effect.

 

3.  The clarified syrup is decolorized by filtering it through a bed of activated carbon.

 

4.  The purified syrup is repeatedly crystallized under vacuum and then separated from the molasses by centrifuge to produce refined white sugar.

 

5.  Light and dark brown sugar are produced by mixing molasses back in with the white refined sugar.

 

6.  Granulated sugar is made by first thoroughly drying it and then blowing cool air through it for several days.

History

 

What is the history of sugarcane?

 

Sugar cane is a giant grass that is native to India, particularly the Ganges delta. However currently there are only related wild plants that reside in that region.  The classic species, thought to be a result of mutation, is no longer found anywhere in India, except in its cultivated form. The ‘sweet redd’ which is known as ‘sweet calamus’ of the Bible, was brought to the Mediterranean by caravans in the early days of import business, 3rd century B.C.

 

Sugar cane syrup was rare and expensive, and used in medicines by the Egyptians and Phoenicians, before the Greeks and Romans. Until modern times sugar was a luxury item.

 

Top Producers:

 

Who are the top producers of sugarcane?

 

Brazil, India, China, Thailand, Pakistan

  

Sugar Beets:  Latin Name

Beta vulgaris

 

What are sugar beets?  How do sugar beets grow?

 

The sugar beet is a white conical root with a flat crown and a rosette of leaves.  Sugar is formed through photosynthesis in the leaves that is then stored as sugar in the root which contains 12 to 21% sugar, 75%water and 5% pulp depending on the growing conditions and the cultivar.  Pulp and molasses are byproducts of the beet crop and add 10% to the value of the harvest.  

 

The average weight of a sugar beet ranges from 1 lb. to over 2 lbs.  The foliage is a bright rich green color and grows over 14 inches tall. Sugar beets grow best in temperate zones where they are planted in spring and harvested in the fall.  In warmer areas where there are no freezing temperatures, they are planted in the fall and harvested in spring. 

 

Propagation:

 

How are sugar beets propagated?

 

Before planting, fields are deeply ploughed as the beets grow better in loose soil.  Then seeds are planted into the rows and thinned, so they are spaced about a foot apart.  Sugar beets reach maturity 90 to 95 days after planting.

 

Harvest:

 

How are sugar beets harvested?

 

Sugar beets mature 90 to 95 days after planting.  They are harvested when the leaves turn yellow as the plant pushes all its nutrients into the beet root for winter storage.  This is when the sugar content in the beets is at its highest, so this is the best time to harvest.   The beets are harvested by a mechanical harvester with a load truck following alongside to catch the beets and then transported to a processing plant.

 

Processing:

How are sugar beets processed?

1.  The beet roots are washed, mechanically sliced into strips, or “cossettes”, and passed through diffusers to extract sugar content into a water solution.  In the diffusers, the water and cossettes go in opposite directions which more efficiently draws the sugar out of the cossettes.

2.  This sugar water is called “raw juice.”  The cossettes, pulp now, are then pressed to extract even more sucrose out of them and then sold as animal feed.  The sucrose is added back to the raw juice.  

3.  Bacterial breakdown of the sucrose is into undesirable sugars and acids is sometimes chemically arrested by adding formaldehyde to the mixture and carefully monitoring pH levels.

4.  Carbonation:  The raw juice is mixed with a solution of lime (calcium hydroxide in water) and carbon dioxide is bubbled through it in order to entrap and absorb impurities and to chemically stabilize the mixture. The heavier particles settle out in the tanks.  This process may be repeated in order to further purify the raw juice.  This cleaner light brown solution is called “thin juice.”

.5.  Evaporation:  The thin juice is concentrated by means of evaporation to make a thick syrup which is then crystallized or can be stored for later use.

6.  Crystallization:

The thick juice is fed to the crystallizers, recycled sugar is dissolved into it and the resulting syrup is called "mother liquor". 

This is concentrated further by boiling under vacuum in large vessels and seeded with fine sugar crystals. These crystals grow, as sugar from the mother liquor forms around them. 

The resulting sugar crystal and syrup mix is called massecuite (which means "cooked mass" in French). 

The massecuite is passed to a centrifuge where the liquid is removed from the sugar crystals. 

Remaining syrup is rinsed off with water and the crystals dried in a granulator using warm air. The recycled syrup is fed into another crystallizer from which a second batch of sugar is produced. 

This sugar ("raw") is of lower quality with a lot of color and impurities and is the main source of the sugar that is re-dissolved into the mother liquor. 

The syrup from the raw sugar is also sent to a crystalliser. From this a very low quality sugar crystal is produced (known in some systems as "AP sugar") that is also redissolved. 

The syrup that is separated is also called molasses; still containing sugar but with too many impurities to be economically processed further.  Only molasses from sugarcane is consumable.

History

 

What is the history of sugar beets?

 

Olivier de Serres first extracted sugar from beets in the 16th century when he discovered that boiling them yielded a juice similar to that made from sugar cane (except it was red in color at the time).  In 1747, Professor Marggraf discovered that the sugar in beets had the same properties as that of sugar cane.  However it wasn’t until 1801 that the first beet factory was opened  in Silesia.  Napoleon compelled farmers to begin devoting large acreages to growing sugar beets and prohibited the importation of sugar from the Caribbean.  Sugar beet production started in the United States around 1890 and in the mid-1920’s in the United Kingdom.

 

Producers

 

Who are the top producers of sugar beets?

 

France, the United States, Germany, Russia and Ukraine are the biggest producers of sugar derived from sugar beets.

 

Which is better:  Beet or Cane sugar?

 

Some people taste no difference between cane sugar and beet sugar unless they are tasted side by side. 

For baking, always use cane sugar, especially when using brown sugar.  Brown beet sugar is actually white beet sugar with sugarcane molasses mixed back in for taste, texture and color. 

If you suspect you might have an allergy to sugar from one source, try using the other.  It may make a big difference.

 

Health benefits and impact on health:

 

What are the health benefits of sugar?  What is the impact of sugar on health?

 

Sugar intake should be severely limited as its impact on health can be, and often is, very bad.  Too much sugar contributes to increased rates of obesity, diabetes, inflammation and dental problems.  

 

The only good reasons for eating sugar are 1) to sweeten foods that are nutritious but otherwise unpalatable; and 2) for an extra burst of quick energy - especially for athletes just before they compete.