Evaluation of size reduction on the yield and quality of celery seed oil

The effect of grinding/flaking with and without pre-cooling of celery seeds on the yield and physical and chemical characteristics of volatile oil was evaluated. For smaller batches (200 g) with pre chilling and flaking, yields of oil were marginally but consistently higher (2.20%), compared to grinding celery at ambient temperature using a mini plate mill (1.9%) and with waring blender (1.8%). With flaking at room temperature the yield of oil was 2.0%. However, in large batches (10 kg), with steam distillation the yield of steam distilled oil was significantly higher for flaking (1.76%) as compared to the hammer mill powdering (1.4%), both at room temperature. Extraction of volatile oil from celery powder or flakes follows first order kinetics with an variance value of 0.04. Gas chromatograph (GC) and gas chromatograph-mass spectra (MS) analysis showed that in case of flaking, the volatile oil had higher levels of limonene, the major volatile compound and sedanenolide, the major character impact compound being present in almost equal quantities in both the cases of flakes and powder. Selective collection of volatile oil at different intervals of time of distillation gave products of different flavour profiles. Flaking had the advantage of higher yields of the volatile oil with better flavour quality. It was also observed that flaking of celery helped in overcoming the problem of clogging and choking which is associated with the conventional grinding, (c) 2006 Elsevier Ltd. All rights reserved.