Chemical and Physical Characterization of Dehydrated Functional Fenugreek Leaf Powder

Abstract

Fenugreek (Trigonella foenum-graecum) is a popular and most ancient recorded medicinal herb. Leaves and seeds of which are used as important ingredient in Indian cuisine. Even after harvesting of leaves, respiration and transpiration continues and affect quality during post harvest handling operations. Shape of leaf being as infinite slab having enormous exposed surface area to volume ratio, the enhanced respiration and transpiration losses are reported to be extremely high and losses the quality in short duration. Thus this important leafy vegetable is often categorized under highly perishable category of foods. Attempts have been made to process the fenugreek leaves into shelf stable form having maximum possible retention of quality characteristics in its dehydrated form. The dehydration process was subjected in a cabinet drier maintained at the isothermal temperatures ranging from 50 to 90 °C with an interval of 10 °C. The identified time and temperature combination based on the physico-chemical parameters, the combination method of different temperature during dehydration process was recommended. The obtained dehydrated leaves were converted into powdered form before fractionated and characterized on the basis of chemical, physical and optical parameters. As expected the dehydration process was governed by the subjected pretreatment, dehydration temperature and exposure time during dehydration operation. The quality of obtained dehydrated fractional functional fenugreek powder was found better for the fenugreek leaves dehydrated at an initial temperature of 70 °C with finishing temperature of 60 °C with its counterpart. The chlorophyll content has been found to be enhanced by more than seven times in powdered fraction of fenugreek leaf with the loss of merely 12 %. The antioxidant effect on DPPH radical scavenging activity was found to be 377 mg/g. The non-polar solvent extract of fenugreek leaf powder was revealed the presence of various phyto-chemicals having potentially important nutritional, therapeutic and medicinal values. The antimicrobial aspect of fenugreek leaf powder was checked on selected bacterial strains.