- J A Duvenhage
- Merensky Technological Services, P O Box 14, Duivelskloof 0835
- 1993
Fruit were treated with a sodium metabisulphite dip on its own, as well as combined with hydrochloric acid dips, vitafilm, Semperfresh G and modified atmosphere packaging. The effect of the treatments on post-harvest disease, browning, colour, and taste was evaluated. Sodium metabisulphite dip followed by hydrochloric acid dips or Vitafilm gave the best results when taking into account all four criteria.
Summary:
- The study evaluates sodium metabisulphite (Na2S2O5) dips alone and combined with hydrochloric acid (HCl) dips, Vitafilm, Semperfresh G, and modified atmosphere packaging (Freshpak) on post-harvest decay, browning, color, and taste of litchis.
- Sodium metabisulphite dips followed by HCl dips or Vitafilm treatments gave the best overall results considering browning reduction, disease control, color retention, and taste.
- Browning and disease were scored from 0 (none) to 5 (severe), while color and taste were rated from 0 (unacceptable) to 5 (excellent).
- All sodium metabisulphite treatments significantly reduced browning compared to untreated controls; Semperfresh G performed poorly.
- For the cultivar Mauritius, sodium metabisulphite with HCl dip for five minutes resulted in the best color development and good taste.
- For the cultivar Madras, sodium metabisulphite combined with HCl dips also gave the best color development and showed significant browning reduction.
- Sodium metabisulphite combined with Vitafilm showed good browning reduction but higher disease incidence on Madras litchis compared to other treatments.
- Taste was generally better for sodium metabisulphite treatments compared to SO2 fumigation, which sometimes impaired flavor.
- The study highlights the need for alternatives to SO2 fumigation due to residue limits and negative taste effects.
- Overall, sodium metabisulphite combined with low pH hydrochloric acid dips is a promising alternative for maintaining litchi fruit quality during storage and export.
- Results were influenced by a dry season that minimized disease development, so further testing is suggested.