Pg. 17-18 SO₂ Residu van Berookte Mauritius-Lietsjies

Faktore wat die S0₂-residuvlakke van berookte lietsjies mag bei’nvloed is ondersoek. Alhoewel residuvlakke ongewensde variasie getoon het, is ‘n aantal verskille opgemerk. In die skil was die S0₂ °residu’s 10 tot 20 maal hoer as in die vrugvleis, terwyl residuvlakke afneem tydens berging. Bepalings onmiddellik na beroking, sowel as na berging vir een tot vier weke by 2°C, het gemiddelde residuvlakke van 61,20; 7,91; 4,28; 1,98 en 1,66 dpm getoon. Feitlik geen korrelasie kon gevind word tussen residuvlakke en faktore soos natheid, klein verskille in die hoeveelheid swael gebrand, berokingstyd, SO₂-konsenfrasie tydens beroking, vrugvolwassenheid, humiditeit of temperatuur nie. Verskille tussen vrugte van verskillende produsente is egter opgemerk.

Summary:

• The study investigated factors influencing sulfur dioxide (SO₂) residue levels on fumigated Mauritius lychees.
• SO₂ residues were found to be 10 to 20 times higher in the fruit skin compared to the flesh.
• Residue levels significantly decreased during storage at 2°C, from an average of 61.20 ppm immediately after fumigation to 1.66 ppm after four weeks.
• No significant correlation was found between residue levels and factors like wetness of fruit, small differences in sulfur quantity burnt, fumigation time, SO₂ concentration, fruit maturity, humidity, or temperature.
• Variations in residue levels were noted between fruits from different producers.
• The current maximum allowable residue levels are 10 ppm in the flesh and 250 ppm on the skin.
• The study found that residue levels often exceeded these limits immediately after fumigation but declined over storage, suggesting residues are unlikely to pose problems upon export after several weeks.
• No meaningful differences in residue were observed between dry and wet fruit during fumigation regarding residue levels, but wet packaging still causes spotting issues.
• The amount of sulfur burnt during fumigation impacted residue levels and color; heavier fumigation tended to correlate with higher residues and better bleaching of fruit color.
• Fumigation until the fruit skin shows a cream color with slight pink bleaching is recommended for efficacy.
• Packaging in plastic bags post-fumigation controls post-harvest decay well but may trap sulfur residues, requiring monitoring.
• Internal inspections during export may allow certain residue limits depending on transport method (e.g., boat vs air freight).
• More specific experimental trials are needed to understand the effects of various factors on residue levels due to compensations producers already make in practice.
• The study concludes current residue limits are acceptable under normal conditions but emphasizes timing of residue sampling after fumigation as critical.