|Infobox on Molasses
|Example of Molasses
|Stowage factor (in m3/t)
|0,79 m3/t (bulk)
|Humidity / moisture
Molasses is a viscous by-product of the refining of sugarcane, grapes, or sugar beets into sugar. The quality of molasses depends on the maturity of the source plant, the amount of sugar extracted, and the method employed.
To make molasses, the cane of a sugar plant is harvested and stripped of its leaves. Its juice is extracted usually by crushing or mashing, but also by cutting. The juice is boiled to concentrate it, which promotes the crystallisation of the sugar. The result of this first boiling and of the sugar crystals is first syrup, usually referred to in the Southern states of the USA as "cane syrup" as opposed to molasses, which has the highest sugar content because comparatively little sugar has been extracted from the source. Second molasses is created from a second boiling and sugar extraction, and has a slight bitter tinge to its taste.
The third boiling of the sugar syrup yields blackstrap molasses, known for its robust flavour. The majority of sucrose from the original juice has been crystallised and removed. The food energy content of blackstrap molasses is still mostly from the small remaining sugar content. However, unlike refined sugars, it contains trace amounts of vitamins and significant amounts of several minerals. Blackstrap molasses is a source of calcium, magnesium, potassium, and iron; one tablespoon provides up to 20% of the daily value of each of those nutrients. Blackstrap has long been sold as a health supplement. It is also used in the manufacture of Ethyl Alcohol for industry and as an ingredient in cattle feed.
Sugar beet molasses
Molasses made from sugar beet is different from sugarcane molasses. Only the syrup left from the final crystal ligation stage is called molasses; intermediate syrups are referred to as high green and low green, and these are recycled within the crystallization plant to maximize extraction. Beet molasses is about 50% sugar by dry weight, predominantly sucrose, but also contains significant amounts of glucose and fructose. Beet molasses is limited in biotin (vitamin H or B7) for cell growth; hence, it may need to be supplemented with a biotin source. The non-sugar content includes many salts, such as calcium, potassium, oxalate, and chloride. It also contains the compounds betaine and the trisaccharide raffinose. These are either as a result of concentration from the original plant material or as a result of chemicals used in the processing, and make it unpalatable to humans. Hence it is mainly used as an additive to animal feed (called "molassed sugar beet feed") or as a fermentation feedstock.
It is possible to extract additional sugar from beet molasses through a process known as molasses desugarisation. This technique exploits industrial-scale chromatography to separate sucrose from non-sugar components. The technique is economically viable in trade-protected areas, where the price of sugar is supported above the world market price. Molasses is also used for yeast production.
Shipment / Storage / Risk factors
The two types of molasses commonly carried in bulk by sea are cane and beet molasses. Both types take the form of a thick brown syrup and are produced during the sugar refining operations by removal from the sugar crystals. Cane molasses or blackstrap, which comes from raw cane sugar, is the heavier of the two with its final composition depending on the country of origin, cane maturity and methods of manufacture. Beet molasses is processed from the roots of the sugarbeet and is less viscous molasses than blackstrap. The better grades of both types of molasses can be fermented into alcohol such as rum and can also be used in treacle manufacture. Other uses include animal feedstocks and the production of yeast and organic chemicals.
Molasses is a low value product and the seaborne shipment of the commodity is a restricted market. Only a small number of operators worldwide handle sizeable amounts of the product, these being carried in epoxy or uncoated tanks suitable for products for a specific gravity of 1,4.
Most of this commodity is now carried in bulk in tank vessels and in Deep Tanks of general cargo ships. B/L, C/P, or Contract should be claused to the following effect: - ‘It is expressly agreed that Surveyor’s certificate as to tightness, and Shipper’s certificate as to cleanliness of tank, shall be deemed conclusive evidence that the deep tank in all respects is tight, clean, and suitable for the reception and carriage of Molasses in bulk’.
From the tanker it is discharged by ship’s pumps, but in the case of ordinary cargo vessels by special pumps, generally , though not always, provided by consignees, pumps being suspended by chain blocks or otherwise from hatch beams and lowered from time to time as the discharging proceeds.
The molasses is heated by means of steam coils as ordinarily fitted for carriage of vegetable oil, and discharging commences at a temperature of about 32°C. As this commodity expands rapidly with heat, care must be exercised when loading to provide space for expansion, due to difference between loading temperature and the highest anticipated up to commencement of discharge.
To avoid damage to general cargo by heat to be used to liquefy the molasses, care must be exercised during the loading, to avoid the stowage of cargo liable to melt or otherwise to be damaged by heat, near Deep Tank bulkheads or on its flats, etc.
When the discharging is fairly under way it is more or less customary to direct live steam into the molasses by means of flexible hose and so raise the temperature as high as 40°C, in order to expedite pumping. However, care should be taken not to permit the temperature to rise above 40°C or that prescribed in writing by consignees, as too high a temperature causes damage by ‘singeing’.
Tanks which have carried molasses should, as soon as possible after discharge, be thoroughly cleaned by washing and scrubbing, using salt water – fresh water or steam do not lend themselves to this purpose – and as this commodity exercises a corrosive effect on iron and steel, the cleaning should be thorough in order to prevent deterioration of the ship structure.
Ships which are proceeding to an up-river or fresh water port to discharge Molasses should fill a ballast tank with clean sea water for this purpose.
Molasses in combination with salt water forms a corrosive compound which, if not removed, will cause corrosion back of frames, brackets, etc. To ensure the removal of all traces of such, a thorough swilling down of all parts of the tank with fresh water should be made after the cleaning process is over. That will also expedite the drying of the tank.