Process optimization for grinding of turmeric at sub-ambient temperature
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Date
2019-09
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G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand)
Abstract
Turmeric (Curcuma longa L.), is one the most important spices of India. India ranks first at world level, in turmeric production and within the country, Andhra Pradesh is the major producer followed by Tamil Nadu, Orissa and Karnataka. Turmeric is rich in natural antioxidants and possess numerous medicinal properties including anti-oxidant, anti-protozoal, anti-viral, anti-carcinogenic activities. Grinding of turmeric is an important unit operation to convert raw turmeric into usable form, but unfortunately, it increases the temperature of the product leading to loss of valuable constituents like volatile oil, curcumin, flavouring compounds and colour. Increase in temperature also renders clogging of sieves and high-power consumption due to heat dissipation during grinding. The present investigation was thus aimed to minimize losses of valuable constituents of turmeric by initial pre-cooling, reducing heat generation during grinding by cooling through means of jacketed chilled water circulation and manipulation of particle size. Turmeric rhizomes were pre-cooled at -18°C and then first coarse ground with jacketed chilled water circulation at temperatures i.e. control, 0, -10 and -20°C. It was again subjected to cooling at -18°C and finally fine ground at temperatures control, 0, -10 and -20°C. Particle size also plays important role in determining the quality of ground turmeric hence it was subjected to five sieve sizes i.e. >300, 150-300, 106-150, 90-106 and >90 μm. The process of turmeric was optimized by circulating chilled water at -20°C and sieving the ground turmeric by 90-106 μm sieve size. Grinding by optimized process resulted in significant increase in per cent yield, curcumin, anti-oxidant activity, volatile oil, oleoresin and colour i.e. L, a and b values i.e. 91.66, 2.64, 74.66, 0.63, 7.33, 86.41, - 8.70 and 76.96 respectively as compared to 87.56, 0.80, 64, 0.56, 3.66, 86.70, -7.77 and 62.17 respectively at control temperatures. The cost of optimized product was also Rs 45.34 lesser than market turmeric powder.
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