Processing of cauliflower by ohmic heating: influence of precooking on firmness

Abstract

The feasibility of processing cauli¯ower by ohmic heating was investigated. Firstly, cauli¯ower¯orets were precooked in tap water at low temperatures (40±70°C) for 0 to 60 min. A control sample was cooked at 95°C for 5 min. No signi®cant textural differences were found between samples treated at 40 or 50°C and fresh samples, but the ®rmness of samples cooked above 60°C decreased. The effect of precooking time was not found to be signi®cant. Secondly, low temperature precooking was performed in salted water for 30 min and followed by ohmic heating (holding time 30 s at 135°C). After ohmic heating,¯orets pretreated at low temperatures were ®rmer than control samples. The ®rmness of¯orets precooked at 40°C or 50°C was considerably increased (b300%) compared to those precooked at 95°C. Low-temperature precooking increased the ®rmness of cauli¯ower subjected to ohmic heating. The experimental results show that ohmic heating combined with low-temperature precooking in saline solutions offers a viable solution to high temperature/short time sterilisation of cauli¯ower¯orets.