Sugarcane (
Saccharum officinarum) is one of the important commercial crops used for the manufacture of sugar, jaggery and other products. Sugarcane is cultivated in India in an area of approximately 5.15 million hectares with production of approximately 383 million tonnes (MY 2018-19). Jaggery provides an alternative market to sugarcane growers. About 26% of the sugarcane produced is diverted for jaggery production. Jaggery is an unrefined, non-centrifugal whole cane sugar eaten across the globe. Jaggery is a rich blend of minerals and vitamins, which makes it the healthiest sugar in the sweetener category
(Gopalan et al., 1991). The Jaggery is very widely used not only in individual households but also in many eateries, restaurants, clubs and hostels and it has certain industrial applications as well. Due to its wide applications, the market for jaggery is continuously growing. Presently jaggery is being produced on small scale by traditional method. The jaggery has a good demand in domestic and foreign market
(Banakar et al., 2012). The quality and price of jaggery is depends upon its external features like color and texture
(Selvi et al., 2022). A best quality jaggery is judged by its features like golden yellow in color, hard in texture, crystalline structure and its unique sweet taste, less in impurities like molasses and some crystals and low in moisture
(Shweta et al., 2019). Colour is one of the important criteria determining the grade of gur/jaggery. Normally jaggery with light colour is preferred for consumption.
Jaggery production and market scenario
India is the world’s second largest producer of sugarcane. The production of sugarcane in India stands at 354 million tons. Out of the entire jaggery production in the world, 70% production (approximately 10 million tons) takes place in India alone. Approximately 40% of India’s jaggery is exported
(Madan et al., 2004). India during the last couple of years has produced more than 300 MMT of sugarcane out of which, about 79.91% is utilized in producing white sugar, 11.29% in producing jaggery and khandsari, 8.80% as cane juice, seed cane for the next harvest
etc. Sugar recovery for different states in India lies in the range of 8.89 to 11.26% on cane (MY 2018-19), whereas, recovery of jaggery (gur) ranges from 10-13% depending upon the variety, sugarcane quality, soil texture, irrigation facilities, time of cane crushing etc
(Narendra Mohan and Anushka Agarwal 2020).
Nutritional importance of jaggery
The jaggery contains approximately 60-85% sucrose, 5-15% glucose and fructose, 0.4% of protein, 0.1 g of fat. Also it is rich in important minerals
viz., magnesium 70-90 mg, potassium 10-56 mg, phosphorus 20-90 mg, sodium 19-30 mg, iron 10-13 mg, manganese 0.2-0.5 mg, zinc 0.2- 0.4 mg, copper 0.1-0.9 mg and chloride 5.3 mg per 100 g of jaggery), vitamins (
viz., Vitamin A-3.8 mg, Vitamin B1-0.01 mg, Vitamin B2-0.06 mg, Vitamin B5-0.01 mg, Vitamin B6-0.01 mg, Vitamin C-7.00 mg, Vitamin D2-6.50 mg, Vitamin E-111.30 mg, Vitamin PP-7.00 mg) and protein-280 mg per 100 g of jaggery, which can be made available to the masses to mitigate the problems of mal nutrition and under nutrition. The micronutrients present in the jaggery possess antitoxic and anti-carcinogenic properties
(Selvi et al., 2022). But, sensing a demand for jaggery from health-conscious consumers, farmers have started constructing jaggery units.
Nowadays, two processes are mainly being followed in India to produce jaggery. One is old indigenous method and the other is modern sulphitation process. A typical Khandsari and Jaggery industry have 1-20 furnaces. The size of the Khandsari sugar units varies between 50-1000- tons of cane crushing capacity per day (Tones Crushed per Day), whereas for Jaggery it ranges 1-15 TCD. The recovery of sugar ranges from 7% (traditional process) to 9% (modern process) whereas recovery for jaggery it is 9% (traditional process) to 13% (modern process) of cane crushed. There is extremely low thermal efficiency of the traditional method of producing jaggery. Since these devices are typically built by local artesian, a large part of the energy is lost into the environment in the form of flue gases. It needs elevated ability and more manual labour due to long heating activity. The conventional method of producing jaggery cannot be used for mass production due to batch processing
(Kumar and Kumar 2018). In India jaggery is produced in the winter and spring seasons and the rest of the year is processed there. In order to preserve the quality of jaggery, the conventional storage methods such as earthen pot, wooden box and metal drum,
etc. are not very successful. Jaggery storage is a major issue as it absorbs moisture from the air which changes its properties. Conventional storage methods, primarily under all environmental conditions, are not very effective in the rainy season. More than 10% of the $0.6 million worth of jaggery produced in India is estimated to be lost each year due to degradation under normal storage processes
(Mandal et al., 2006).
Although the Jaggery industry has grown several folds over the decades, there has been no organized effort to improve its performance, efficiency and recovery. Hence, this review paper explain the traditional method of jaggery making plants and storage, their constraints and to overcome problems associated with traditional methods of jaggery making, advanced modified method of jaaggery making process and storage was summarized here.
Traditional jaggery manufacturing process
Jaggery manufacturing is a continuous cycle of heat and mass transfer in which the fresh sugarcane juice are used; bagasses are used as raw material for fuel. The progressive heating and stirring of sugarcane juice in an open pan changes the sugarcane juice from liquid to semi-solid, which further becomes solid after cooling. The traditional jaggery manufacturing process involves a number of operations that are performed by skilled and semi-skilled persons
(Kumar and Kumar 2018). Depending on the type of canes used, sugarcane juice varies in colour from grey dark green to light yellow
(Rao et al., 2007). In addition to this molasses is also a valuable byproduct of the jaggery manufacturing process that also serves as fuel. Thus this industry does not depend on additional fossil fuel for its production. Clarificants are the organic and inorganic components used in the process of making jaggery to clarify the raw sugarcane juice
(Carter 1954).
The traditional Jaggery manufacturing process involves a number of operations which are shown in Fig 1.
Classical jaggery production operations and equipments
The first step in the manufacturing of jaggery is the weighing of the cane and then transferred by crushing it in a crusher to extract sugarcane juice (Kelhua). In order to crush canes, vertical or horizontal crushers with three rollers are typically used. Conventionally, a couple of bullocks run a crusher. Now the bullocks are replaced by a diesel engine for a day. The performance of vertical and horizontal crusher juice recovery ranges from 50-55 per cent and 55-60 per cent respectively. The crushing efficiency can be increased from 27 per cent to 80 per cent using multiple crusher and hot water. This method is not possible in conventional method tiny jaggery making unit
(Rao et al., 2007). The schematic views of different sugarcane crushers are shown in Fig 2.
(Kumar and Kumar 2018).
In the masonry settling tank, crushed sugarcane juice is stored for some time to isolate the heavier impurities due to sedimentation process. There clear juice is transferred to boiling pan with continuous stirring action and juice will be heated in boiling pan. The juice will be boiled using bagasse as a fuel. The time required for boiling of juice is normally depends on workers engaged in the process. After boiling the juice will be allowed for clarifications in which impurities will be removed. The quality of jaggery depends on clarifier used in the process
(Narian 2002;
Asokan and Rupa 2008).
Recent technologies in jaggery manufacturing process
Three kinds of jaggery manufacturing plants are historically used in India, namely, single-pan, two-pan and multi-pan (three or four pan) jaggery manufacturing plants. In typical jaggery production plants, pans used are typically rectangular with a flat surface or hemispherical or cone shaped. Several modifications have been done in the pan type used in the units in order to increase the thermal efficiency. They are shown in Table 1. The schematic view of temporary single pan jaggery making plant is shown in Fig 3a.
In case of two pan jaaggery making plants, two pans are fitted at the top of the furnace. First pan is the gutter pan fixed as first pan in which sugarcane juice will be boiled. The second is boiling pan, the juice will be heated at desired temperature level. The schematic view of two-pan jaggery making furnace is shown in Fig 3b. In addition, to boiling and gutter pans, one or two more pans will be fitted in a series manner in multi pan jaggery system. The sugarcane juice will be pre heated in first two pans. Then pre heated juice will be moved to the boiling pan for actual heating. In the plants, direction of juice conversion is opposite to the direction of movement of hot thermal energy. The other structural features of three or four pan model are similar to that of two pan jaggery making model. Performance of the jaggery making plant is more in three and four pan model due to more heat generation. But, the use of three or four pan type does not indicate a noticeable change of increase of thermal efficiency and a decrease in the consumption of bagasse. The schematic view of four-pan jaggery making plant is illustrated in Fig 3c.
Anwar (2014) developed an efficiency booster, at the bottom of the single pan jaggery manufacturing plant. The schematic view of efficiency booster used in jaggery manufacturing plant is shown in Fig 4.
Anwar (2010) increased the heat utilization efficiency of two-pan jaggery making plant by using fins at the bottom of boiling and gutter pans along with the saving of bagasse. The schematic views of fins at the bottom of boiling and gutter pans used in jaggery manufacturing plant is shown in Fig 5.
From the above discussion, it is noted that, the efficiency of traditional plants producing jaggery is very poor because they are manufactured by local artisans. In order to improve the efficiency of jaggery making following method has been used.
Jaggery making using freeze pre-concentration of sugarcane juice
Rane and Jabade (2005) proposed a new idea of the heat pump dependent freeze concentration system (FCS) for the concentration of sugarcane juice in a jaggery method. In this method water is extracted from sugarcane juice by selective freezing in the form of ice.
The schematic view of freeze concentration system used in jaggery manufacturing plant is shown in Fig 6. In this process, water is selectively freezed and separated from juice to form ice and concentrated juice. Freezing point of juice changes from -1.5 to -4.6
oC
(Mathlouthi and Reiser, 1995) for 20 to 40 minutes. During this initial 63% water removal, bagasse is saved and that can be recycled in field for composting. Concentrated juice is obtained at low temperature. This juice is further concentrated using steam jacketed pan with vegetative clarificants. Altogether, it improves colour of jaggery from dark brown to golden yellow which has higher market value.
Storage of jaggery
The quality and storability of jaggery depends on varieties used for cultivation, quality and quantity of inputs used in the jaggery making plant. The major problem associated with jaggery storage is the presence of inverts of sugars and mineral salts, which, being hygroscopic in nature, absorb moisture particularly during the moonsoon season when the ambient humidity is high leads to spoilage of the jaggery materials. It was estimated that during monsoon season more than 10% of total jaggery produced in India of value 0.6 million US $ is lost annually
(Mandal et al., 2006). For good consistency and should be kept at 43-61 per cent relative humidity. The storage of jaggery is a significant function for its preservation under adverse environmental conditions. Jaggery production begins in the month of September/October in India and continues until March/April and is processed for the rest of the year. It has been estimated that every year between one third and one half of the total output of jaggery is stored
(Kumar et al., 2013b). The pretreatment with nitric oxide of sugarcane juice provides better colour and sucrose amount, which helps increase the shelf life of jaggery
(Hussain et al., 2012).
The researchers used various conventional and enhanced methods to increase the shelf life of jaggery. For jaggery storage, which varies from region to region, usually earthen pot, wood box and metal drums are used. Jaggery is stored in the shape of a heap in some areas and filled with cane garbage, bagasse, wheat straw, cottonseed, furnace ash, palmyra leaf mat, rice husk,
etc. to protect it from direct contact with moist air
(Rai and Paul 2007). The various studies carried out on storage and packaging of jaggery is listed in Table 2 and Table 3, respectively.
It is observed that from the above discussion the jaggery is stored in traditional method and modern scientific methods
viz., tin, painted earthen pot, low temperature storage, drying cum storage bin, nitrogen PET film and whey coatings. The storage of jaggery in a whey coated drying cum storage bin is found to be most efficient in preserving the consistency of jaggery. The greenhouse drying of jaggery is an effective way to extract and preserve the moisture content of jaggery for a longer period of time.
Varieties suitable for jaggery making
Varieties having high sucrose content, low reducing sugars, high purity, low colloids, low organic non sugars such as nitrogen, phenols, amino acids, starch , gums and high level of phosphate should be chosen for jaggery production. The varieties suitable for jaggery making are always found to be equally suitable for sugar. The quality of cane is a main genetic factor also many other factors like climate, soil type, crop management etc affect the jaggery production. The sugarcane variety suitable for jaggery should have specific characters like early maturity, less fibre content, high purity of juice
etc. Some of the Tamil Nadu sugarcane varieties are specifically suitable for jaggery making CoG 6, CO 0212, CO 06022 and CO 11015 (Atulya).
The greenhouse drying of jaggery is an effective way to extract and preserve the moisture content of jaggery for a longer period of time. The various studies carried out on solar drying of jaggery are listed in Table 4. The schematic views of natural and forced convection greenhouse jaggery dryers are shown in Fig 7a and b.
Summary
Traditional jaggery making process involves consumption of more manual source and long hours of operation for the production. Also, during the traditional method of operation, the flue gas emanating from direct fire under the pan releases harmful chemicals in the boiling house which are hazardous and cause respiratory problems to workers. In order to solve this problem, two-pan, three-pan and four-pan plants are used to absorb hot flue gases with optimum thermal capacity. In this way, many researches have been carried out to increase the efficiency of the jaggery making plant. Among the methods studied, multi-pan plants with a heat pump based freeze concentration system is found to be a good approach for the efficient production of jaggery. Since, storage is also a major concern; the conventional method of jaggery storage is not very successful to maintain the quality. Compare all the storage methods, whey coated drying cum storage bin is most efficient in maintaining the consistency of jaggery for a longer time. So, the key challenge before the researchers is the optimization of jaggery manufacturing processes, improvement in conventional jaggery manufacturing plants and preservation of jaggery.
Way forward
The Scientists/researchers have to work more effectively in the production and storage of jaggery to meet these challenges in the future. To make the jaggery manufacturing process eco-friendly, the government and researchers should encourage the farmers to use solar energy in heating sugarcane juice.
