Pg. 21-24 Invloed van Bergtyd Voor en Na SO₂-Behandeling op Skilkleur, Vrugbederg en Swael Residuvlakke van Lietsjies

Die invloed van bergtyd by kamertemperatuur voor en na SO₂-behandeling op die vruggehalte van HLH Mauritius- en Red McLean (Madras)-lietsjies is geevalueer. Vrugte is gebreg by 21°C vir 0,5, 1, 2, 4, 18 en 30 uur voor SO₂-behandeling en vir 1, 2, 4, 12, 24 en 48 uur na SO₂-behandeling. Na ‘n koelbergingsperiode van 30 dae by 2°C, is geen betekenisvolle verskille ten opsigte van skilkleur en vrugbederf tussen die verskillende behandelings gevind nie. Vrugte behoort egter nie /anger as 24 uur voor of na SO₂-behandeling geberg te word nie, aangesien die vrug vog en fermheid verloor.

Swael-residu’s was hoer as die vereiste 10 dpm in die vrugvleis by vrugte wat in polietileen plastieksakkies verpak is, maar heeltemal aanvaarbaar by vrugte wat oop verpak was. Alhoewel na-smake van swael waargeneem is by vrugte wat in polietileen plastieksakkies verpak is, was die eetgehalte oor die algemeen aanvaarbaar.

Summary:

• The study evaluated the influence of storage time at room temperature (21°C) before and after SO₂ treatment on the skin color, post-harvest decay, and sulfur residue levels in HLH Mauritius and McLean’s Red (Madras) litchi cultivars.
• Litchis were stored for various periods (0.5 to 30 hours before SO₂; 1 to 48 hours after SO₂) at room temperature before packaging and cold storage at 2°C for 30 days.
• No significant differences were found in skin color or post-harvest decay among treatments after 30 days cold storage, but fruit should not be stored longer than 24 hours at room temperature due to moisture and firmness loss.
• Sulfur residues in the fruit flesh exceeded the 10 ppm limit when fruit was packed in polyethylene plastic bags, but residues were acceptable in open packing.
• The eating quality was generally good, except that fruit packed in polyethylene bags had a sulfur aftertaste.
• The litchis tested are non-climacteric fruit that must be fully ripe before harvest to ensure good red skin color and quality; improper maturity leads to poor color development and quality.
• Paper bagging on the tree improved skin color during storage likely due to higher humidity inside the bags.
• SO₂ residues were high immediately after fumigation but broke down to acceptable levels during cold storage.
• There was variability in sulfur residue absorption even in fruit from the same cultivar and carton, and Madras cultivars were more prone to sulfur aftertaste after long storage.
• The study recommends limiting room temperature storage before or after SO₂ treatment to maximize quality and minimize decay and sulfur residues.
• The findings support the importance of fruit maturity, packaging method, and timing of SO₂ treatment to optimize export litchi quality and residue compliance.
• The study was funded by the South African Litchi Growers’ Association.