Overview
ISO 2168:1974 - "Table grapes - Guide to cold storage" is an international guide for postharvest handling and refrigerated storage of table grape varieties originating from Vitis vinifera. The standard describes harvesting practices, packing and pre-cooling, optimum cold‑storage conditions (temperature, relative humidity, air circulation), storage life expectations, adjunct treatments (sulphur dioxide fumigation or in-package SO2 generators), and limits of application (Annex A). Annex B provides examples of varieties recommended for long‑term storage.
Key topics and technical requirements
- Harvest and packing
- Harvest grapes mature; avoid damaged or visibly fungal fruit.
- Pack in a single layer where possible; contents should be homogeneous and not overly tight.
- Avoid holding wet fruit; if immediate cooling is not possible, keep in shade and cool within 24 hours.
- Optimal cold‑storage conditions
- Temperature: Optimal range about −1.5 °C to 0 °C (greenhouse-grown grapes: approximately 0 °C to +1 °C).
- Relative humidity: Maintain 90–95% RH to prevent shrivel of stems and pedicels.
- Air circulation: Ensure good air mixing (guide example coefficient 30–40) and provide controlled air renewal.
- Storage life: Varies by variety and preharvest conditions; biologically possible up to 6 months, but maintaining green, turgid stems is difficult beyond ~4 months.
- Sanitation and antifungal controls
- Disinfect cold rooms and packaging before use.
- Apply antifungal treatments when authorized; control Botrytis with approved methods.
- Sulphur dioxide (SO2) treatments
- The guide describes short fumigations on chamber entry (examples: higher short‑dose or lower longer exposures) and periodic treatments (e.g., every 10–15 days at lower concentrations).
- For continuous or in‑package protection, the use of metabisulfite SO2 generators or impregnated sachets is described; target in‑package SO2 ranges are indicated (guide: 80–300 ppm in permanent regimes).
- Use of sealed packaging without gas exchange can produce off‑flavours; films should have perforations to allow gas removal.
- Limitations
- Annex A stresses local variability: not all varieties or climates are fully covered and specialists should adapt conditions accordingly.
- ISO 2169 is referenced for definitions and measurement methods of storage physical parameters.
Practical applications
- Enables growers, packers, cold‑storage operators and exporters to set evidence‑based parameters for postharvest handling and refrigerated storage of table grapes.
- Helps design packaging strategies (single‑layer packing, perforated films, in‑package SO2 generators) and cold‑chain procedures (pre‑cooling, temperature and humidity control).
- Informs quality control, shelf‑life planning, and export logistics to reduce fungal decay and maintain fruit quality.
Who should use this standard
- Grape growers and vineyard managers
- Packinghouse and cold‑store operators
- Postharvest technologists and food safety managers
- Exporters, distributors and cold‑chain logistics planners
- Researchers developing postharvest treatments and storage protocols
Related standards
- ISO 2169 - referenced for definitions and measurement of refrigeration physical quantities.
- Annex B of ISO 2168 lists example varieties (e.g., Thompson Seedless/Sultanine, Muscat, Italia, Cardinal) recommended for storage under the guide’s conditions.
Keywords: ISO 2168, table grapes cold storage, Vitis vinifera, temperature, relative humidity, sulphur dioxide, SO2 generators, postharvest handling, storage life, grape varieties.