Physiological and enzymatic changes during post-harvest low temperature storage periods and the manifestation of symptoms associated with Internal Browning in pineapples.

Internal Browning (IB) is one of the most important physiological disorders, which affects storability of pineapple fruits. Factors causing the browning reaction, including polyphenol oxidase (PPO) activity, phenylalanine ammonia lyase (PAL) activity, peroxidase (POD) activity and the non-enzymatic production with the low temperature storage period were tested. Mature pineapple fruits (cv Mauritius') were stored at 15°C for 4 weeks and afterwards examined for internal quality and biochemical parameters. It was found that PPO and POD were correlated with the storage period and the appearance of storage symptoms. Results further indicated that non-enzymatic browning and PAL were not directly related to IB development. To verify these results, polyacrylamide gel electrophoresis (PAGE) was carried out with the peroxidase in the fruit and PAGE of the peroxidase in the fruits affected by the storage period indicated differences in the band intensities.