India is the 4th largest producer of ethanol after United States of America (USA), China, Brazil having more than 300 distilleries with a production capacity of about 3.2 billion litres mainly by fermentation of sugarcane molasses. Out of the total available ethanol, about 45% is used for potable liquor, about 40% is used as industrial solvent in chemical industry and for blending in fuel and for other applications. There is a continuous growth in demand for ethanol in India due to growth in industrial applications and its use as blending agent in fuel. However, the production capacities are lagging with respect to the market demand for the ethanol and the amount of ethanol currently being produced in India is not sufficient to meet domestic demand. The ongoing efforts to reduce the fuel import burden on the country, the Central government decision to increase the blending percentage of alcohol in petrol encouraging the ethanol producers to increase their capacities and to explore alternate feedstock for ethanol fermentation. This enabled sugar mills to produce ethanol by diverting cane juice towards ethanol production and availability of ethanol for the Ethanol Blended Petrol (EBP) programme. The support from government to provide higher compensation price for ethanol produced from sugar juice or syrup and B molasses would aid in reducing excess sugar stocks and impacting the sugar industry capacity to pay arears to sugarcane farmers. All sugar mills/ distilleries are planning to take to take benefit of the scheme by participating in supply ethanol for the Ethanol Blended Petrol (EBP) programme.
Molasses is the key by product of sugar industry and is one of the main feedstocks for ethanol production while going forward sugarcane juice and syrup are going to play a significant share as feedstock in ethanol fermentation that may include primary/secondary/mixed/clear juice and syrup which has concentrated juice with total dissolved solid content more than 50 Brix. Clarified sugarcane juice, from the milling section, is concentrated to 60 brix in the falling film evaporation section to convert juice into syrup. Operating the distillery throughout the year is the challenge with out the storage of raw material for off-season, though cane juice can be used during season, it is very difficult to maintain its sugar content as well as keep it free from microbial contamination in the most compact manner. However, the cane syrup could be stored and utilized as a raw material for off-season consumption (90 days operation).
Challenges in syrup preservations:
The Solubility of Sucrose changes with varying temperature and at low temperatures the sucrose might get crystallized in syrup.
The sucrose tends to breakdown into monomers, which are more susceptible for microbial degradation. The pH is an indicator for microbial degradation and is also evident from formation of by-products such as gluconic acid, Lactic acid, and Acetic acid.
Numerous preservation methods being investigated by researchers for the sugarcane syrup consists of chemical, thermal, and non-thermal methods that includes usage of enzymes prior to storage. Enzymes will also be dosed in the storage tank at regular intervals for achieving extended shelf life of cane syrup. Simultaneously, the stored syrup will be cooled by recirculation with a provision of inert gas blanketing in the storage tank head space to avoid contamination when the syrup comes in to contact with air. It is also proposed to consume syrup on first-in, first out basis. We at Catalysts, has Govt of India approved in-house Research and Development centre, working on development of syrup storage process with the help of our proprietary enzyme formulations to provide cost effective tailormade solutions to industry and our valuable customers.
Credits: Valérie Heuzé / AFZ)
Schematic of process of sugarcane to produce ethanol and sugar. (Credits: John A Dutton)