Harvest and Maturity Guidelines for Pome Fruit
Characteristics of Fruit Ripening
Pome fruit are climacteric, meaning they produce the ripening hormone ethylene autocatalytically—once ethylene is produced, its production increases exponentially. During development and maturation, fruit undergoes:
- Loss of chlorophyll (loss of green colour)
- Development of anthocyanins (in red cultivars)
- Conversion of starch to sugar
- Production of flavour volatiles (important for eating quality)
The picking and handling protocol is designed to help producers manage fruit according to these physiological changes.
Fruit passes through pre-climacteric, climacteric, and post-climacteric phases (including senescence). Knowing the onset, duration, and termination of these phases allows for optimal handling. These changes are referred to as changes in maturity. Cooling after harvest and cold storage are aimed at maintaining fruit quality, making knowledge of fruit maturity or age essential.
Fruit Maturity and Its Role in Quality
Fruit must be harvested at the optimum stage of maturity to maximize quality and storage potential. Various picking and storage parameters are used to determine this, based on maturity indexing programmes (e.g., Hortec, 1983–2001).
- Release date (start of harvest): Fruit reaches physiological maturity and will ripen to good eating quality after storage. This is the minimum maturity for harvest and is best for long-term storage.
- Optimum harvest: Usually 10–14 days after the release date, balancing colour, size, and internal quality.
- Post-optimum harvest: Fruit is eating ripe with best flavour, suitable for short to medium-term storage.
Table 1: Maturity Criteria
Apples
| Cultivar | Maximum Firmness (kg) | %TSS | Starch (% white) | Acid % | Minimum Firmness (kg) | Minimum Acid % |
|---|---|---|---|---|---|---|
| Royal Gala | 8.4 | 11.0 | 15 | 0.40 | 7.0 | 0.35 |
| Golden Delicious | 7.8 | 12.0 | 15 | 0.50 | 7.0 | 0.40 |
| Red Delicious | 8.0 | 11.0 | 10 | 0.30 | 7.3 | 0.25 |
| Braeburn | 8.6 | 11.5 | 20 | 0.60 | 8.0 | 0.40 |
| Granny Smith | 7.8 | 11.0 | 20 | 0.75 | 6.8 | 0.55 |
| Fuji | 8.5 | 13.5 | 20 | 0.45 | 7.0 | 0.35 |
| Cripps’ Pink | 8.7 | 12.5 | 10 | 0.75 | 7.5 | 0.55 |
| Cripps’ Red | 9.1 | 12.5 | 15 | 0.75 | 8.5 | 0.60 |
Pears
| Cultivar | Maximum Firmness (kg) | %TSS | Acid % | Minimum Firmness (kg) | Minimum Acid % |
|---|---|---|---|---|---|
| Williams BC | 10.5 | 11 | 0.35 | 7.2 | 0.30 |
| Beurre Hardy | 6.4 | 11 | 0.45 | 4.1 | 0.35 |
| Beurre Bosc | 8.1 | 12.5 | 0.30 | 4.5 | 0.20 |
| Doyenne du Comice | 6.8 | 12.0 | 0.35 | 3.6 | 0.25 |
| Packham’s Triumph | 8.0 | 11.5 | 0.30 | 5.0 | 0.20 |
| Forelle | 6.8 | 13.5 | 0.30 | 4.5 | 0.20 |
Harvest Timing and Methods
- Immature fruit: Will not ripen or develop good taste; high risk of defects (bitter pit, wilting, scald).
- Optimum maturity: Best for medium to long-term storage; minimized risk of defects.
- Post-optimum: Best flavour, short to medium storage; higher risk of yellowing, bruising, mealiness, greasiness.
Harvesting Methods
- Strip pick: All fruit harvested at once; not recommended due to maturity variation.
- Selective/multiple pick: Recommended; fruit picked by size or colour for more uniform maturity.
Picking Windows
- Pre-optimum: First 3–4 days after release; good storage potential, taste develops after storage, risk of scald/bitter pit.
- Optimum: Middle 7–10 days; best for storage and taste.
- Post-optimum: Short storage, superior taste, risk of over-maturity defects.
Additional Harvest Considerations
- Minimum residue levels (MRLs): Observe pesticide/fungicide withholding periods.
- Export standards: Comply with national and market-specific standards.
- Pears: Sensitive to picking maturity and moisture loss; use selective picking and prevent shrivel.
- Apples: Gala, Fuji, and Pink Lady® are challenging for harvest decisions; selective picking is beneficial.
Practical Harvest Guidelines
- Clean bins with hot water/steam and sanitizers.
- Use bin liners appropriately to minimize bruising.
- Avoid picking during or after rain.
- Keep bins covered on hot days.
- Pickers should avoid jewelry and have short nails.
- Use mats to minimize bruising when emptying picking bags.
- Pick during cooler periods of the day.
- Coordinate delivery to minimize waiting times.
- Keep fruit under cover during transport and at depots.
Note: Every precaution taken during harvest and handling positively affects fruit quality.