ศูนย์นวัตกรรมเทคโนโลยีหลังการเก็บเกี่ยว

Effects of Chitosan Coating with Citric Acid and Potassium Sorbate on Postharvest Decay and Browning of Longan Fruit during Cold Storage

W. Apai, V. Sardsud, P. Boonprasom and U. Sardsud

Book of Abstracts, Asia-Pacific Symposium on Assuring Quality and Safety of Agri-Foods, August 4-6, 2008, Radisson Hotel, Bangkok, Thailand.

2008

บทคัดย่อ

The efficacy of chitosan (Cts) in combination with citric acid (CA) and potassium sorbate (PS) o­n quality retention in the longan was evaluated as an alternative to SO₂ fumigation. Fresh longan fruits were dipped in the solutions of 1.2% Cts+3.0% CA+3.0% PS at two levels of pH solution: 2.8 and 3.3 as compared to those being dipped in coating componest; 3.0% CA+3.0% PS (pH 2.4) alone. After being dipped, the fruits were air-dried, packed in foam tray wrapped with 11µm thick PVC film and then stored at 4±1°C, 90% RH. The non-treated fruit (negative control) and SO2 fumigation (positive control) were used as control. The result revealed that except for SO₂, dipping fruits in Cts+CA+PS (pH-3.3) significantly delayed pericarp browning. The result was indicated by the lowest browning index and the highest pericarp color values (L*, C* and h°) for 32 days. In the mean time, the deferment of pericarp browning effect for fruits treated with Cts+CA+PS (pH 2.8), coating component (CA+PS) and the control fruit was o­nly for 24, 20 and 28 days, respectively. Fruits coating with Cts+CA+PS (pH 3.3) showed reduced decay, peericarp pH, weight loss, PPO activity, total phenol loss and retained excellent fruit color acceptability including eatable quality during cold storage and a transfer to simulate marketing shelf life at ambient condition. In contrast, the fruits with SO₂ showed the worst edible quality because of off-odor effects. Chitosan along with CA+pS (pH 3.3) could well prevent sorbic acid degradation in pericarp when compared to those applying CA+PS alone without chitosan.

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