Development of Mechanized System for Production of Date-Palm Jaggery Granules

Making of date-palm jaggery (popularly known as khejur gur) with its characteristic aroma and flavor is very popular all over India for making various sweet dishes and confectionery products. It is available only for a short duration between middle of November and end of January. The production of solid jaggery includes sap collection (juice) by tapping, filtration, concentration by boiling, cooling of concentrated juice followed by moulding, drying, and storage. Making date-palm jaggery from the raw juice is an art and requires some skill to get the characteristic aroma bearing product with optimum stickiness and colour. Solid jaggery deteriorates rapidly and becomes liquid within 1 or 2 weeks due to its moisture content, invert sugar, and hygroscopic nature. Granular jaggery having low moisture content (1 - 2%d.b) is very popular, tenders several advantages, such as extended shelf-life, easy handling and distribution, high demand for domestic and international markets. It could be made from either solid jaggery or concentrated juice. Therefore, a manually-powered operated granulator (20 kg capacity) was designed, developed, and tested with 5 levels of moisture content (8.4 to 16.25 %db) and 5 levels of rotational speed (48 - 132 rpm) of blades for the production of desired size of jaggery granules. The mass mean diameter of the particles varied linearly with the moisture content of the feed, yielding particles having an average size of 656 µm (Dp) for feed containing 8.4 (%db) moisture. The mean particle size was as low as 700 µm when the machine was operated at 132 rpm with feed moisture content of 12 (%db). The average particle size of 1000 µm is obtained at feed moisture content of 9.0 (%db) and the agitator rotational speed of 76 rpm.