Pg. 35 Die Effek van Lae pH-Oplossing na SO₂-Behandeling op Skilkleur, Vrugbederf en Swael-Residuvlakke in die Vrugvleis van Lietsjievrugte na Koelverberging

Lietsiievrugte van beide die HLH Mauritius- en Red McLean-kultivars (Madras), is na SO₂behandeling gedoop in lae pH-oplossings van 0,25, 0,5 en 1 persent sitroensuur, soutsuur (HGI) en salpetersuur (HNO₃). Uitwendige skilkleur na ‘n 30-dae-koelbergingsperiode by 2°C was by al die behandefings beter as die van vrugte wat net met SO₂ behandel is. ‘n Vol roof kleur is verkry by die Madras-kultivar wat met HG/ behandel is. Geen probleme is ondervind met vrugbederf nie en by al die behandelings is 100 persent beheer verkry. Swael-residuvlakke in die vrugvleis was by die meeste behandelings laer as die vereiste 10 dpm. ‘n Onverklaarbare 219, 11 dpm het by die 1 persent HNO₃-behandeling in HLH Mauritius-vrugte voorgekom. Geen onaanvaarbare smake/na-smake is waargeneem by enige van die behandelings nie.

Summary:

• Litchi fruit from HLH Mauritius and Red McLean (Madras) cultivars was treated post SO₂ fumigation with low pH solutions (0.25%, 0.5%, 1%) of citric acid, hydrochloric acid (HCl), and nitric acid (HNO₃).
• After 30 days storage at 2°C, fruit treated with low pH solutions had superior external skin color compared to standard SO₂-only treated fruit.
• Madras cultivar treated with hydrochloric acid showed a full red color after storage.
• All treatments provided complete control of post-harvest decay with no fruit spoilage observed.
• Sulfur residues in fruit flesh were below the international maximum limit of 10 ppm, except in the HLH Mauritius fruit treated with 1% HNO₃, which showed an unusually high 219.11 ppm sulfur residue.
• No unacceptable flavors or aftertastes were detected in any treatments.
• The study confirms that low pH post-treatment can restore red skin color lost during SO₂ treatment while maintaining disease control and minimizing sulfur residue.
• Maintaining attractive red skin is important as litchi peel browns quickly after harvest, which affects marketability though not internal fruit quality.
• This research supports improved post-harvest handling practices for extended shelf life, market appeal, and compliance with export residue standards.