Co-products of sugar beets and sugar cane
Although cane and beet are both sources of sugar, their processing also generates a number of interesting co-products for the agricultural sector and certain agri-food and industrial activities. Nothing goes to waste in the sugar sector: everything is retrieved, recycled and recovered.
In 2017, there were seven sugar companies in mainland France, operating 25 sugar processing plants located in the north of France. Production, in regulatory terms, was 4.7 million tonnes of beet sugar (2016-2017).
The sugar sector (farming, sugar processing plants, sugar plants/distilleries and refineries) directly employ 44,500 people and generate a turnover of 3.8 billion euros. Beets have other valuable resources, in the form of co-products from the sugar beet extraction process. Mainly used in the form of molasses and pulp, these co-products each have a wide variety of applications.
Once the juice has been extracted, pressed or dehydrated beet pulp provides an ideal foodstuff for cattle. Pulp can also be used to produce industrial pectin or dietary fibre contained in foods that have been “enriched with fibre”.
The equivalent of pulp in sugar cane production is called bagasse.With its high calorific value (4,000 kcal per kilo), bagasse is used as a fuel in sugar production plants, where it often represents the only source of energy. Surplus bagasse plays a role in the production of wax, paper, and thermal or sound insulation.
Slime is the result of filtering. It is pressed before being compacted into a filterpress cake. Filterpress cakes are used as calcium fertiliser on agricultural land.
A non-crystallisable substance obtained from the third boiling of sugar syrup, beet molasses contains 50% of its own weight in sugar. It has numerous uses. It is found in a variety of products, including certain animal feeds. The fermentation properties of molasses form part of the production process of baker’s yeast, amino acids used as condiments, and citric acid in confectionary products and non-alcoholic drinks. Molasses is also used in the production of alcohol.
Cane molasses is still enjoyed by some North American consumers,who value its high vitamin B and mineral content. The only drawback is its appearance, a viscous brown paste that’s far from appetizing.
Once the principal substances have been extracted from the molasses, the residual product, called vinasse, is not discarded. Rich in nitrogen, it is one of the products used in the production of high-quality flour for animal feed.
Alcohol derived from sugar beet juice can be made from pure sugar beet juice or from beet molasses. In the first case, the sugar beets are processed to obtain a sweet juice and beet pulps, as in a sugar processing plant. The sugar juice is left to ferment and then distilled to produce alcohol. A tonne of sugar beets is equal to an average 90 to 100 litres of alcohol.
The production of alcohol using molasses follows the same process, with the exception that the molasses is diluted before fermentation.One tonne of molasses yields approximately 300 litres of alcohol. Alcohol derived from sugar beet juice is suitable for human consumption (spirits, perfume, vinegar and pharmaceutical products) and ideal for use in household products (cleaning fluids, methylated spirits, etc.) and chemical substances (solvents, etc.).
Alcohol produced from sugar cane is, of course, more commonly known as rum. Agricultural or plantation rum results from the fermentation and distillation of sugar cane juice. Industrial rum is produced from cane molasses.
The alcohol derived from these processes is also called ethanol or bioethanol. When mixed with petrol, bioethanol provides a more environmentally-friendly fuel because it is made from plant matter (biomasse).
Plants use CO2 to grow, they use photosynthesis which captures solar energy to transform CO2 and water (H2O) into their basic components and recombine carbon and hydrogen. CO2 is therefore “captured” by these plants. CO2 emitted by car exhaust fumes is captured by the plant as it grows.