Effect of active-modified atmosphere packaging on the respiration rate and quality of pomegranate arils (cv. Wonderful) Kalenga Banda a , Oluwafemi J. Caleb a,b , Karin Jacobs c , Umezuruike Linus Opara a,b, * a Postharvest Technology Research Laboratory, South African Research Chair in Postharvest Technology, Department of Horticultural Science, Faculty of AgriSciences, Stellenbosch University, Private Bag X1, Stellenbosch 7602, South Africa b Postharvest Technology Research Laboratory, South African Research Chair in Postharvest Technology, Department of Food Science, Faculty of AgriSciences, Stellenbosch University, Private Bag X1, Stellenbosch 7602, South Africa c Department of Microbiology, Faculty of Science, Stellenbosch University, Private Bag X1, Stellenbosch 7602, South Africa A R T I C L E I N F O Article history: Received 2 February 2015 Received in revised form 3 June 2015 Accepted 6 June 2015 Available online 23 June 2015 Keywords: Shelf life Respiration rate Anthocyanin Aerobic mesophilic bacteria Packaging A B S T R A C T Two experiments were conducted to investigate the effects of active- and passive-modified atmosphere packaging (MAP) on respiration rate (RR) and quality attributes of minimally processed pomegranate arils (cv. Wonderful) stored at 5  C for 12 d. In experiment 1, pomegranate arils were packaged in low barrier bi-axially oriented polyester (BOP) film under active-MA (5 kPa O 2 + 10 kPa CO 2 , 30 kPa O 2 + 40 kPa CO 2 ), passive-MA and in clamshell trays. In experiment 2, a high barrier Polylid 1 film was used with arils packaged under three active-MAs (5 kPa O 2 + 10 kPa CO 2 + 85 kPa N 2 ; 30 kPa O 2 + 10 kPa O 2 + 60 kPa N 2 ; 100 kPa N 2 ) and passive-MA. Arils packed in clamshell trays had lowest RR (RCO 2 ) compared to the other MA treatments in experiment 1, ranging from 41.1 nmol kg 1 s 1 on day 3 to 238.8 nmol kg 1 s 1 on day 12. Respiration rate of arils packaged in the high barrier polylid film was significantly affected by MA treatments. At the end of 12 d storage, total anthocyanin content (TAC) in arils was highest for clamshell packages (0.31  0.01 g L 1 ) and lowest in passive-MAP (0.27  0.02 g L 1 ). Packaging arils in high O 2 atmosphere and 100 kPa N 2 significantly lower aerobic mesophilic bacteria counts throughout the storage duration. Based on sensory scores obtained and microbial load, the shelf life for arils packaged in clamshell trays, passive-MA, and high O 2 level MA was 6, 9 and 12 d, respectively. ã2015 Elsevier B.V. All rights reserved. 1. Introduction Modified atmosphere packaging (MAP) combined with low temperature storage has been successfully used to prolong the shelf life of fresh fruit and vegetables (Mahajan et al., 2014). Modified atmospheres are achieved by hermetically sealing fresh respiring produce in polymeric film and allowing the atmosphere within the package to be modified passively by the interplay of produce respiration rate (RR) and the film permeability properties, or actively by flushing the desired gas mixtures inside a package before sealing (Kader and Watkins, 2000; Rico et al., 2007; Mangaraj et al., 2009). Modified atmosphere packaging slows down physiological and biochemical processes and retards senescence (Caleb et al., 2012a). Thereby maintaining packaged produce freshness, quality attributes and microbial safety. Failure to create this suitable atmosphere may result in a shortened shelf life (Mangaraj et al., 2009). Suitable equilibrium atmospheres are achieved by proper matching of fresh produce RR and film permeability characteristics (Jacxsens et al., 2002; Kader, 2002; Caleb et al., 2012a). Desired atmospheric equilibrium/compositions inside pack- aged fresh produce are low oxygen (O 2 ) (2–5 kPa) and/or moderate carbon dioxide (CO 2 ) (10 kPa) (Rico et al., 2007; Sandhya, 2010). Previous studies have reported on the RR of minimally processing pomegranate arils under different conditions (Ersan et al., 2010; Caleb et al., 2012b). Ayhan and Estürk (2009) reported an increase in antioxidant activity and lower mesophilic bacteria counts in minimally processed pomegranate arils (cv. Hicaznar) stored under super atmospheric O 2 (70 kPa) atmospheres compared to those stored under low O 2 (5 kPa) and in normal air at 5  C. Super atmospheric O 2 atmospheres (>21 kPa) have also been used in MAP of minimally processed products because of their ability to prevent anaerobic fermentation, inhibit enzymatic discolouration and microbial growth (Jacxsens et al., 2001). O 2 concentrations >25 kPa are nonetheless considered highly explosive and, as they pose a hazard should be used with caution (Jacxsens et al., 2001). * Corresponding author at: Postharvest Technology Research Laboratory, South African Research Chair in Postharvest Technology, Department of Horticultural Science, Faculty of AgriSciences, Stellenbosch University, Private Bag X1, Stellenbosch 7602, South Africa. Fax: +27 21 808 3743. E-mail address: opara@sun.ac.za (U.L. Opara). http://dx.doi.org/10.1016/j.postharvbio.2015.06.002 0925-5214/ ã 2015 Elsevier B.V. All rights reserved. Postharvest Biology and Technology 109 (2015) 97–105 Contents lists available at ScienceDirect Postharvest Biology and Technology journal homepa ge: www.elsev ier.com/locate/postharvbio