Engineering Properties of Peeled and Unpeeled Multiplier Onion

Abstract

Multiplier onion (Allium cepa L. var aggregatum. Don.) is mainly used for its unique flavour in seasoning dishes. The unpeeled onions are processed at farm level by means of primary processing and by secondary processing various products like paste, flakes, powder could be produced from peeled onions. For the design of processing and handling equipment knowledge of engineering properties is essential. The engineering properties of peeled and unpeeled multiplier onion were determined. The average values of the physical properties of unpeeled onion were recorded for bulk density and true density as 636.621 and 1526.825 kg/m3 respectively. Similarly for peeled onions, the bulk and true density were 627.03 and 1108.74 kg/m3 respectively. The moisture present in peeled and unpeeled onion was 77.66 % and 74.43% (w.b) respectively. The TSS of multiplier onion was found to be 20° Brix for both peeled and unpeeled samples. The colour values were also measured using colour flex meter for the peeled and unpeeled onions. The frictional properties including coefficient of friction, filling and emptying angle of repose were also measured. Mechanical properties were determined by using a texture analyser. The firmness was measured in terms of penetrating force and crushing strength which were recorded to be 8.59 N and 124.93 N respectively for peeled and 12.00 N and 138.35 N respectively for unpeeled onions.