Effect of different extraction methods on yield and physico-chemical properties of garden cress (Lepidium sativam L.) oil

Abstract

Effect of different extraction methods on yield and physico-chemical properties of garden cress oil was
studied. Oil from the dried garden cress seeds were extracted by screw press, solvent extraction (without
heating) and soxhlet extraction method. Physical properties studied were specific gravity, viscosity and colour,
whereas, chemical properties analyzed were peroxide value, acid value and iodine value. Soxhlet extraction
was found to give highest yield of oil. Non-significant difference was observed for specific gravity of oil
extracted by all methods. Viscosity of the oil extracted with screw press was highest (53.7 mPa.s) than
solvent extracted oil and soxhlet extracted oil (39.9 and 42.7 mPa.s, respectively). Oil extracted by soxhlet
method was darker in colour than the solvent extracted. Peroxide value (2.53 meq.kg-1) and acid value (0.74
mg KOH.g-1) were higher for oil extracted with the soxhlet extraction method followed by solvent and screw
press extraction method (1.27, 0.69 meq.kg-1 and 0.83, 0.61 mg KOH.g-1, respectively) whereas, iodine value
was highest (134.2 g I2.100g-1) for solvent extraction method followed by soxhlet extraction and screw press
method (131.7, 97.3 g I2.100g-1, respectively). Fatty acid profile and tocopherols content analysis of the oil
extracted by soxhlet method showed that, garden cress seed oil contains 34.46 % of alfa linolenic acid and
971.6 ppm total tocopherols. Oil stored in polyvinyl terephthalate bottle for 90 days showed significant increase
in peroxide (25.8meq.kg-1).