Harvesting and Postharvest management

Harvesting and Postharvest management

         Since apple is climacteric fruit, the maturity of fruits does not coincide with ripening. The fruits usually do not attain fully ripe edible quality on the tree while harvesting. The fruits should be harvested at proper picking maturity to attain proper edible quality at ripening. Picking of immature fruits results in poor quality fruits lacking flavour and taste which shrivel during storage. Over-mature fruits develop soft scald and internal breakdown with poor shelf-life. There are several maturity indices which can be adopted in proper fruit harvesting. The TSS of fruit pulp, ease in separation of fruit from spur, change in ground surface colour from green to pale, change in seed colour to light brown, fruit firmness and days from full bloom to harvest are some reliable maturity indices for apple which can be considered singly or in combination.

          All the fruits do not mature evenly on trees depending on the time and number of flower flushes. Thus more than one pickings are required. Apple fruits should be picked in such a way that bruising and stem punctures are avoided and pedicel must remain with fruit. Apple should be grasped between index finger, middle finger and thumb, and quick upward twist of wrist will easily pluck the fruit along with pedicel. Picked fruit should be placed softly in the picking bags or baskets. The fruits should be transferred carefully from picking baskets to boxes or baskets be transported to packing houses for grading and packing.

Precooling

           After picking, the fruits should be placed in a cool and ventilated place to remove field heat before packing. Air cooler, cold water sprinkling or fruit washing with water also helps quick removal of field heat. Keeping fruits over-night near the tree basins for cooling down is another practical way to remove field heat. Fruit surface must be free of moisture before grading, wrapping or packing in cartons.

Grading

             Apples are graded according to fruit size and fruit appearance or quality. On the basis of fruit size, apples are graded manually in 6 grades. On the basis of fruit colour, shape, quality and appearance, apple fruits can be graded in 3 or more quality grades. These grades are designated as AAA, AA and A; A, B, C; or extra fancy, fancy class I and fancy class II. For size grading, mechanical graders with washing and waxing facilities are available in India now.

 Packaging

             Apples are packed in wooden boxes. Size of wooden boxes used in different apple-growing areas of India are different and carry about 10kg or 20kg fruits in a box. Standard-sized wooden boxes are 45.7cm long, 30.5cm wide, and 25.4, 27.5 and 30.5cm in height according to size of grade.

Corrugated-fibre board (CFB) cartons are also available for packing apples. Such cartons are of 2 types—universal cartons and telescopic tray-pack cartons. The CFB cartons not only save the precious wood and forest wealth but result in very less fruit bruising (3.5%) which fetch good market price. The usual dimensions of CFB cartons with trays are 50.4cm × 30.3cm × 28.2cm (outer jacket) and 50.0cm × 30.0cm × 28.2cm (inner case).

Storage

           Apples have long storage life compared to other fruits. However, different varieties have different storability. Deterioration of fruits starts after climacteric stage. However, shelf-life of apples can be prolonged by providing optimal storage conditions. The cold storage retards fruit deterioration and reduces decay from pathogens and shrivelling from water loss. The recommended storage temperature for apple is –1.1°–0°C which is about 0.8°–1.8°C above the average freezing point of most apple varieties. The relative humidity of 85–90% should be maintained in cold storages. Most apple varieties can be stored for 4–8 months after harvesting, Ambri has the longest storage life.