The scientists at Ghent University (Belgium) have investigated the effect of initial headspace oxygen (IH) on microbial and sensorial quality of fresh-cut pineapple. This study is only the first part of a larger research project with the main aim of optimizing the shelf-life of fresh-cut fruit by using MAP (Modified Atmosphere Packaging).For the study, pineapple agar was used to simulate fresh-cut pineapple at first. The agar was inoculated with yeasts and the initial microbial load was 102-3 CFU/cm2 of agar. The inoculated petri plates were individually packaged testing different initial headspace oxygen levels (0, 1, 3, 5 and 21%). The packaged plated were then incubated at 7°C.
The microbial analyses to control yeast growth were performed on days 0, 2, 4, 6 and 8 for Candida argentea and Candida sake and on days 2, 4, 6, 9 and 12 for Meyerozyma caribbica. The petri plates were also used for identification and quantification of the volatile organic compounds (VOCs) that can occur during storage.
The same analyses were performed on fresh pineapple cut into cubes, packaged and stored at 7°C for 5 days, testing the same initial headspace oxygen levels (1, 5 and 21%).
Results showed that high initial headspace oxygen level (21%) accelerated yeast growth and favoured the production of VOCs, which were responsible for off-odours and flavour formation.
The scientists conclude that at present a longer shelf-life can be reached when fresh-cut pineapple is packaged using 5% of initial headspace oxygen, however the research will continue for optimizing the shelf-life of fresh-cut pineapple investigating the most effective MAP by combining O2 and CO2 levels.
Source: Zhang B-Y., Samapundo S., Rademaker M., Noseda B., Denon Q., de Baenst I., Sürengil G., De Baets B., Devlieghere F., ‘Effect of initial headspace oxygen level on growth and volatile metabolite production by the specific spoilage microorganisms of fresh-cut pineapple’, 2014, LWT- Food Science and Technology, Vol. 55, pagg. 224-231. Further info: http://www.sciencedirect.com/science/article/pii/S0023643813003046