Response of Two Libyan Soft Date Cultivars to Induced Ripening Under Controlled Atmosphere Conditions

Abstract

Induced ripening under controlled atmosphere (CA) conditions was investigated using two Libyan soft date cultivars, "Bronsi" and "Taboni". An experimental setup consisted of an airtight 15L plastic bottle was used, fruits were filled in the setup at 0.6kg.L-1 bulk density. The setup was also equipped with valves; facilitating real time monitoring and measurement of oxygen (O2), carbon dioxide (CO2) and ethylene (C2H4), in addition to temperature and relative humidity inside the enclosure and throughout the treatments. The ripening process was carried out in two stages; an airtight CA and regular air (RA). In the first stage, fruit ripening was initiated while in the second stage full conversion to Rutab stage and coloring took place. Accumulated CO2 produced was fairly linear for both cultivars, whereas accumulated C2H4 was linear for "Bronsi" and exhibited polynomial trend for "Taboni" cultivar. However, respiration and C2H4 production rates did not follow specific trends, instead; they exhibited peaks that were very much related to fruit ripening. Time-wise, the first ripening stage lasted 22 hours for both cultivars, but the second stage lasted 23 hours for "Bronsi" and 45 hours for "Taboni", while ripening percentages for both cultivars exceeded 90% (w/w). Quality attributes such as color (L, Hue angle and Chroma) and sensory attributes (sweetness, taste and acceptance) for CA induced ripened dates were compared with naturally ripe ones. Results showed no significant differences in color and sensory attributes at (p<0.05). The study demonstrated the potential of using the method for date ripening. Further investigation using other cultivars and improving the current methodology are highly recommended.