Effect of plastic permeability and exposure to light during storage on the quality of minimally processed broccoli and cauliflower Carmen Olarte a, * , Susana Sanz a , J. Federico Echa ´ varri b , Fernando Ayala b a Departamento de Agricultura y Alimentacio ´n, A ´ rea de Tecnologı ´a de los Alimentos, Universidad de La Rioja, C/Madre de Dios, 51, 26006 Logron˜o, Spain b Departamento de Quı ´mica, A ´ rea de Fı ´sica Aplicada, Universidad de La Rioja, C/Madre de Dios, 51, 26006 Logron ˜o, Spain article info Article history: Received 2 July 2007 Received in revised form 12 June 2008 Accepted 1 July 2008 Keywords: Light Broccoli Cauliflower Minimally processed vegetables Packaging films Quality abstract The impact of lighting on minimally processed broccoli and cauliflower packaged in four different film types (PVC and three P-Plus) has been measured and compared. The effect on the sensory quality of storage at 4  C in darkness and under lighting was evaluated. The gas concentration in the packages, pH, mesophilic counts and weight loss was also determined. Neither the type of film used for packaging nor the storage conditions led to changes in the evolution of pH or the microorganism count in broccoli and cauliflower. However, exposure to light stimulated sto- matic opening facilitate the exchange of gases between the plant tissue and the atmosphere within the packaging. Thus, a considerable loss of water vapor was observed in the packages of both vegetables stored in the presence of illumination. Moreover, exposure to light stimulated respiratory activity so that for the cauliflower, the composition of the atmosphere within the packages varied depending on the permeability of the packaging film used and the storage conditions. However, in the case of the broccoli, the increase in respiratory activity due to the lighting was compensated by the photosynthetic activity which took place in these conditions, in such a way that the composition of the atmosphere inside the packs solely depended on the permeability of the film. This difference in the physiological response conditioned the most suitable kind of packaging film in each case. For cauliflower, in conditions of darkness, P-Plus 120 film proved the most suitable for preserving its sensory qualities, while under conditions of lighting, this film did not prove suitable due to its low permeability. However, in broccoli the different packaging films tested behaved in a very similar way whether stored under lighting or in the dark. Ó 2008 Swiss Society of Food Science and Technology. Published by Elsevier Ltd. All rights reserved. 1. Introduction The shelf life of minimally processed vegetables (MPV) is usually extended by means of a combination of appropriate refrigerated storage throughout the entire cold chain, modified atmosphere packaging (MAP) and, of course, good manufacturing and handling practices. However, several factors affect the physiological response of vegetables to minimal processing and these must be controlled in order to extend the shelf life of MPV products. Numerous reports have been published on the use of permeable polymeric films to extend the shelf life of minimally processed vegetables through the modification of the atmospheric conditions of packaging (MAP) (Singh & Goswami, 2006). The effect of the interruption of the cold chain on the physio- logical behavior of MPV products has also been studied by numerous authors (Garcı ´a, Medina, & Olias, 1998; Jacxsens, Devlieghere, & Debevere, 2002). Other factors such as calcium content (Conway & Sams, 1987; Dong, Wrolstad, & Sugar, 2000; Soliva-Fortuny, Oms-Oliu, & Martı ´n-Belloso, 2002) and the presence of ascorbic acid compounds or other additives (Arte ´ s, Escalona, & Arte ´ s-Ferna ´ ndez, 2002; Lamikanra & Watson, 2001; Piagentini, Gu ¨ emes, & Pirovani, 2002) have also been studied. However, only a very small number of studies in the bibliog- raphy make reference to the effect of exposure to light during storage on the physiological response of MPV products. Neverthe- less, the few studies that have examined this effect highlight the importance of this factor in terms of preserving the sensory and nutritional quality of such products (Paradis, Castaigne, Desrosiers, & Willmot, 1995; Sanz, Olarte, Echavarri, & Ayala, 2007). Color is one of the most important sensory attributes that determine food quality which is highly affected by light (Hutchings, 1999). Changes in color during the processing and storage of food products need to be measured and controlled. The most evident symptom of senescence in harvested vegetables is the loss of the green color due to degradation of chlorophyll. The presence of light * Corresponding author. Departamento de Agricultura y Alimentacio ´ n, Complejo Cientı ´fico-Tecnolo ´gico, Universidad de La Rioja, C/Madre de Dios, 51, 26006 Log- ron ˜o, Spain. Tel.: þ34 941 299730; fax: þ34 941 299721. E-mail address: carmen.olarte@unirioja.es (C. Olarte). Contents lists available at ScienceDirect LWT - Food Science and Technology journal homepage: www.elsevier.com/locate/lwt 0023-6438/$34.00 Ó 2008 Swiss Society of Food Science and Technology. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.lwt.2008.07.001 LWT - Food Science and Technology 42 (2009) 402–411