Original article Modelling the respiration rate of minimally processed broccoli (Brassica rapa var. sylvestris) for modified atmosphere package design Elena Torrieri,* Nadia Perone, Silvana Cavella & Paolo Masi Department of Food Science, University of Naples Federico II, Via Universita` 100, Portici (NA), Italy (Received 22 April 2010; Accepted in revised form 16 July 2010) Summary In this work, the effect of temperature, oxygen and carbon dioxide on the respiration rate of minimally processed broccoli was studied to develop suitable modified atmosphere packaging. Respiration rate was measured at 3, 5, 7, 10, 15 and 20 °C under different gas compositions of O 2 and CO 2 (1%, 5%, 10%, 15% and 21% of O 2 with the balance N 2 , a mixture of 10% and 20% of carbon dioxide with the balance air and a mixture at 3% of O 2 and 15% of CO 2 with the balance N 2 ). As expected, temperature was the most influential factor on respiration rate, for all atmospheres tested: increasing the temperature from 3 to 20 °C resulted, for air-stored samples, in a 84% change in oxygen respiration rate, whereas at constant temperature, the respiration rate decreased by 35% with lowering the O 2 concentration from 21% to 1% and by 44% with increasing the CO 2 concentration from 0% to 20%. The Michaelis and Menten competitive model with maximum respiration rate varying against temperature with an Arrhenius equation accurately described the influence of gas composition and temperature on the respiration rate of minimally processed broccoli, and it was used to design a suitable package. Keywords Modified atmosphere packaging design, minimally processed broccoli, respiration rate. Introduction In recent years, consumer demand for freshness and convenience has led to the development and increased production of minimally processed fruits and vegetables. Nevertheless, as fresh-cut products have quite a short shelf-life, modified atmosphere packaging (MAP) is needed to extend the product shelf-life while preserving its freshness attributes (Ahvenainen, 1996). For fresh vegetable products, atmosphere modifica- tion in the package headspace relies on the natural interplay between two processes, the respiration of the product and the transfer of gases through packaging, which leads to an atmosphere enriched in CO 2 and poor in O 2 . This altered gas composition combined with low temperatures reduces the respiration rate (Fonseca et al., 2002b; Tano et al., 2007), proliferation of micro- organisms (Oms-Oliu et al., 2007), physiological weight losses (Habibunnisa et al., 2001), ethylene production (Saxena et al., 2008) and tissue senescence (Lu, 2007). Nevertheless, an incorrectly designed MAP system may be ineffective or even shorten the storage life of a product: if the desired atmosphere is not established rapidly, the package draws no benefit; if O 2 ⁄ CO 2 levels are not within the recommended range, the product may present serious alterations and its storage life may be shortened (Torrieri et al., 2002). The design of an MA package depends on a number of variables related to the product, packaging and environmental factors (Fonseca et al., 2002a; Mahajan, et al., 2007; Torrieri et al., 2009b). To design an MAP, respiration rate of a product is a very important variable, although the most limiting factor of MA-packed fresh-cut fruits and vegetables is the permeability of the films available in the market. Respiration rate is a function of several additional parameters related to the product (type, variety, ripe- ness, degree of cutting) and storage conditions (temper- ature, relative humidity, gas composition). For example, the respiration rate of Piel de Sapo cut melon is reported to depend on the degree of ripeness (Oms-Oliu et al., 2007) and harvest time (Bai et al., 2003), whereas the respiration rate of fresh-cut carrots increased together with the ratio between the package area and product weight (Surjadinata & Cisneros-Zevallos, 2003). Pretel *Correspondent: Fax: +39 08 17754942; e-mail: elena.torrieri@unina.it International Journal of Food Science and Technology 2010, 45, 2186–2193 2186 doi:10.1111/j.1365-2621.2010.02387.x Ó 2010 The Authors. International Journal of Food Science and Technology Ó 2010 Institute of Food Science and Technology