ISO 6662:1983

Overview

ISO 6662:1983 - "Plums - Guide to cold storage" gives practical, internationally agreed guidance for handling and cold-storing selected plum cultivars (Prunus domestica, Prunus insititia and Prunus salicina) intended for fresh supply and some varieties intended for processing. The standard covers harvesting timing, packing, store conditions and optimum procedures, and includes Annex A (optimum temperatures and storage lives for many varieties) and Annex B (limits of application).

Key topics and technical requirements

• Harvesting and packing

  • Harvest during the coolest part of the day (best in the morning, dry weather).
  • Fruits should be whole, healthy, clean and at a suitable maturity; stalks and natural bloom are preferred for fresh market fruit.
  • Pack close to the place of picking into rigid containers (boxes) sized to avoid crushing lower layers.

• Timing and handling

  • Put fruit into cold store as soon as possible and not later than 12 hours after picking.
  • Stores should be disinfected and free from odours; containers handled carefully and placed on pallets.

• Cold store environment

  • Air temperature: Maintain mean air temperature at 1 m above floor and in passages typically 0 to 1 °C for certain non-cold-resistant varieties; specific optimum temperatures by variety are in Annex A.
  • Relative humidity: 90–95% recommended.
  • Air circulation: High air movement (air circulation ratio per ISO 2169) of 30–50 until fruit reach 0–1 °C, then reduced to <30.
  • Leave about 1 m free space between top of stacks and roof; stack to store-permitted height.

• Packaging options

  • Certain varieties recommended for high-pressure polyethylene bags 30–70 µm thick (common capacity 1 kg, sealed with two or three seams). Some plums stored at -1.5 to 0 °C for 2–3 months if suitable.

• End of storage

  • Warm fruit at 2–3 °C for 2–3 days before marketing; after warming, use within about 5 days.
  • Storage life varies widely (approx. 15–90 days depending on variety and conditions); Annex A lists detailed times and temperatures for many cultivars.

Applications and users

ISO 6662:1983 is practical for:

• Plum growers and harvest supervisors planning harvest and pack schedules
• Packing-house operators and cold-storage managers setting temperature, humidity and air-flow regimes
• Exporters and quality-control teams defining shelf-life expectations and packaging protocols
• Processors selecting semi-late/late varieties suitable for cold storage prior to processing
• Horticultural advisors and post-harvest specialists

Related standards and limitations

• Reference: ISO 2169 (Fruits and vegetables - Physical conditions in cold stores - Definitions and measurement) for air circulation metrics.
• Annex B notes the guidance is general: local climate, varietal variability and horticultural practices may require adjustments. ISO 6662 does not address agronomic causes of physiological disorders or storage wastage in detail.