- D. Lemmer and F.J. Kruger
- Institute for Tropical and Subtropical Crops, Private Bag XI 1208, Nelspruit 1200
- 2002
In this study, four trials were conducted to test a range of new modified atmosphere (MA) packaging products, with South African litchis. The films included in the first trial were: Loni Life Solutions® (a low density polythene (L.D.P.) permeable film impregnated with natural minerals) Everfresh® (a MA film impregnated with an ethylene inhibitor) and Xtend®(a MA bag system of which two types were evaluated in the present study). In addition to untreated ‘HLH Mauritius’ fruit, the litchis were dipped for one minute in 1ml/l Desogerme®, a quaternary ammonium compound. All the bags reduced pericarp browning and mass loss after 25 days of cold storage at 1°C. The untreated fruit that were stored in the two types of Xtend® bags retained between 60-70% of their original colour and between 1.4-1.9 % in mass. The litchis stored in the Long Life Solutions® bags, retained 70-75% of their original colour and lost 1.3% mass during the storage period. The best results were obtained with the Everfresh® bags where colour retention was found to be between 80-85% . Unfortunately, the Desogerme® treatments exhibited a very high degree of pericarp browning. It was promising to note that no fungal infection was observed on the untreated fruit stored in the Everfresh® and Long Life® bags. The design of the second trial was similar to the first, but in this case, ‘McLean’s Red’ fruit were used. The results obtained in this trial were comparable with those of the first trial. In the third trial, a poly ethylene chlorine dioxide bag from BTC Products and Services (CC) was evaluated with ‘McLean’s Red’ fruit. The pre-cooled fruit were treated with Desogerme® (1ml/l) and combined solutions of Desogerme® (1 ml/I) and 1% calcium propionate (C6H10CaO4) or 1% sorbic acid (C6H7O2K). The dipped fruit were either dried with a fan before packing or packed in a semi-wet state. The anti-fungal properties of the chlorine dioxide bags were not found to be superior to the control. The wet Desogerme® treatments showed promise in terms of fungal infection and colour retention. However, the effect was not enhanced by the addition of calcium propionate or sorbic acid. In a fourth trial, the different bags were evaluated at 25°C in order to determine their potential on the local market. Very good results were obtained for the BTC Products and Services (CC) polyethylene and Everfresh® bags when packed wet after the Desogerme treatment. Both these bags promoted colour retention and inhibited moisture loss during the 7 day storage period.
Summary:
- Four trials were conducted to test various modified atmosphere (MA) packaging films for their effect on reducing pericarp browning and mass loss in South African litchis.
- The packaging films tested included Long Life Solutions (low-density polyethylene with natural minerals), Everfresh (MA film with ethylene inhibitor), Xtenda MA bag systems, and polyethylene chlorine dioxide bags from BTC Products and Services CC.
- Litchis were stored cold at 1°C for 25 days followed by one week at 13°C, with evaluations of mass loss, fungal infection, firmness, soluble solids, acidity, and external/internal appearance.
- All MA bags reduced pericarp browning and mass loss compared to control fruit stored without bags.
- Everfresh bags achieved the best color retention (80-85%) and inhibited fungal infections effectively.
- Long Life Solutions bags also performed well, retaining 70-75% color and limiting mass loss.
- Xtenda bags were less effective, retaining 60-70% color.
- Desogerme (a quaternary ammonium compound) treatments led to higher browning, especially when fan-dried before packaging.
- The polyethylene chlorine dioxide bags showed no superior antifungal properties compared to control.
- Wet packing after Desogerme treatment combined with polyethylene or Everfresh bags showed promising results for market storage at ambient temperatures (25°C), preserving color and moisture for up to 7 days.
- Fungicide combinations with calcium propionate or sorbic acid did not enhance effects beyond Desogerme alone.
- Care should be taken to exclude insect-damaged fruit from packaging to avoid fermentation and odor issues.
- The study concludes that Everfresh, Long Life Solutions, and BTC polyethylene bags improve litchi storage potential by reducing browning, preserving acids, and slowing mass loss.
- The wet Desogerme treatment protocol with MA packaging shows particular promise for fungal control and color retention, warranting further research and optimization.