Quality of cabbage during long term steaming; phytochemical, texture and colour evaluation P.Y. Nugrahedi a, b, * , M. Dekker a, 1 , B. Widianarko b , R. Verkerk a a Food Quality and Design Group, Department of Agrotechnology and Food Science, Wageningen University, PO Box 17, NL-6700 AAWageningen, The Netherlands b Department of Food Technology, Soegijapranata Catholic University, Jl. Pawiyatan Luhur IV/1 Bendan Duwur, Semarang 50234, Indonesia article info Article history: Received 8 January 2015 Received in revised form 7 August 2015 Accepted 11 August 2015 Available online 12 August 2015 Keywords: Glucosinolate Cabbage Steaming Modelling abstract Steaming has been reported to better retain the glucosinolate (GS) content in Brassica vegetables than boiling. However, there is little information on the GS content, colour, and texture attributes in Brassica vegetables in relation to the duration of steaming. This study investigated the effect of the duration of steaming, which was applied in certain commercial preparation processes, on the GS content, colour, and texture of white cabbage. Results showed that the total accessible content of GSs increases initially during steaming until 10 min followed by a consistent decline up to 180 min. This observed initial in- crease is mainly due to the content of aliphatic GSs rather than indole GSs, which tend to decrease from the start of steaming. A mathematic model for the observed behaviour of the GSs, taking into account several mechanisms, is proposed and fitted to the data. The intensity of the green colour of the cabbage slightly increased during the first 15 min of steaming followed by a decrease onwards. The hardness showed a continuous decline during the entire steaming duration. The study indicates that steaming up to 10 min could promote the health properties as well as the colour and texture attributes of steamed cabbage. © 2015 Elsevier Ltd. All rights reserved. 1. Introduction Intake of Brassica vegetables has been inversely associated with the risk of lung, colorectal, and prostate cancer (Higdon, Delage, Williams, & Dashwood, 2007; Kristal & Lampe, 2002). Several conversion products of glucosinolates (GSs), found almost exclu- sively in Brassica vegetables, are showing biological activities in the human body that are assumed to be responsible for reducing this risk of several cancers (Verhoeven, Verhagen, Goldbohm, van den Brandt, & van Poppel, 1997). In intact plant tissue, GSs are stored in separate compartments from the enzyme myrosinase (thio- glucosidase EC 3.2.1.147). However, upon the plant tissue disrup- tion, GSs are highly prone to hydrolytic degradation catalysed by the enzyme (Fahey, Zalcmann, & Talalay, 2001; Mithen, Dekker, Verkerk, Rabot, & Johnson, 2000). Among the breakdown prod- ucts of the GSs, isothiocyanates have been reported to inhibit phase 1 and to induce phase 2 enzymes that are beneficial with respect to (pro)carcinogen metabolism and excretion (Traka & Mithen, 2009). GSs are water-soluble compounds that may leach into cooking water during vegetable preparation. For example, boiling of Bras- sica vegetables results in 25%e75% decreases in total GS content (Nugrahedi, Verkerk, Widianarko, & Dekker, 2015). Cooking methods that use less water, such as steaming and microwaving, have shown to reduce GS losses (Rungapamestry, Duncan, Fuller, & Ratcliffe, 2006; Song & Thornalley, 2007; Vallejo, Tomas-Barberan, & Garcia-Viguera, 2002; Verkerk & Dekker, 2004). Several types of processing of Brassica vegetables have been studied and many have a pronounced impact on the concentration of GSs and their corre- sponding isothiocyanates (Verkerk et al., 2009). The observed ef- fects can be explained by multiple mechanisms such as i) myrosinase inactivation, ii) cell lysis and leaching of GSs, break- down products, and myrosinase in the cooking water, and iii) thermal degradation of GSs (Nugrahedi et al., 2015). Often, these studies describe various cooking procedures based on the dietary habits and cuisines in the western society. While * Corresponding author. Department of Food Technology, Soegijapranata Catholic University, Jl. Pawiyatan Luhur IV/1 Bendan Duwur, Semarang 50234, Indonesia. E-mail addresses: probo@unika.ac.id (P.Y. Nugrahedi), matthijs.dekker@wur.nl (M. Dekker). 1 For post publication: Food Quality and Design Group, Wageningen University, PO Box 17, NL-6700 AAWageningen, The Netherlands. Contents lists available at ScienceDirect LWT - Food Science and Technology journal homepage: www.elsevier.com/locate/lwt http://dx.doi.org/10.1016/j.lwt.2015.08.034 0023-6438/© 2015 Elsevier Ltd. All rights reserved. LWT - Food Science and Technology 65 (2016) 421e427