Author: S. R. Assumi, T. Angami, H. Rymbai, A. W. Yanthan, P. K. Sinha
Khasi mandarin is one of the most important commercial fruit crops of Northeast India. The region produces about 32,660 thousand tonnes of citrus from an area of 76.81 thousand hectares. Its trees are medium to large with erect habit, dense foliage, both thorny and thorn less. Fruits are depressed, globose to ovate, orange-yellow to bright orange in colour with smooth surface and even base, occasionally short-necked, segments 8 to 10, abundantly juicy which is orange coloured and seed ranging from 9 to 25. Most of the mandarin orchards of the region are 20-50 years old and needs either replanting or rejuvenation. Moreover, due to absence of proper pre and postharvest management practices, a bulk quantity of mandarin gets damaged during the process of handling, transportation, marketing and storage.
Major causes of postharvest loss are-
- 1. Lack of proper maintenance of orchard.
- 2. Mishandling of the produce.
- 3. Improper storage facilities.
- 4. Improper means of distribution.
- 5. Seasonal over production.
Table 1: Post harvest loss at various stages of handling.
| Stage of handling | Percentage (%) |
| Harvesting | 3.25 |
| Grading | 0.75 |
| Transportation | 1.25 |
| Marketing/Storage | |
| Wholesaler | 1.20 |
| Retailer | 7.50 |
| Total loss | 13.95 |
Harvesting : Harvesting of the produce in time reduces the postharvest losses to maximum extent and harvesting at proper maturity allows handlers to begin their work with the best possible quality produce. Maturity indices are some sorts of identification marks/signals that help the growers to harvest their produce at appropriate time. The following indices may be taken into consideration while harvesting.
Table 2: Maturity indices of Khasi mandarin.
| Sl. No. | Indices | Range |
| 1. | Rind colour (visual) | Yellow-orange |
| 2. | Juice content (%) | >49.00 |
| 3. | Days from flowering to harvesting | 230-250 |
| 4. | TSS (°B) | 9.5-10.0 |
| 5. | Titrable acidity (% as citric acid) | 0.75-.081 |
| 6. | TSS:Acid | 12.38-12.97 |
- 1. Better sensory and nutritional qualities of the fruits.
- 2. Increased shelf life of the fruits.
- 3. Reduces the chances of alternate bearing of the tree.
- 4. Post harvest handling for shelf life extension.
Post harvest handling for shelf life extension
Quality of harvested produce cannot be improved after harvest, but can be maintained for certain period during storage with appropriate post harvest treatments. It is important to harvest fruits at proper stage and size and at peak quality. Immature or over mature fruits/vegetables may not last for long in storage as compared to the fruits that picked at proper maturity. Harvested fruits should be kept shaded in the field and handled gently. The produce after harvesting should be pre-cooled to remove field heat, washed, graded and waxed to enhance the keeping quality during storage. Crops destined for storage should be as free as possible from skin breaks, bruises, spots, rots, decay and other deterioration. Bruises and other mechanical damage not only affect appearance, but provide entrance to decay organism as well.
Waxing : The shelf life of the Khasi mandarin fruits could be increased up to 25-30 days when the fruits harvested at optimum maturity are treated with stayfresh wax (1 part wax + 2 parts water). The treated fruits will have minimum weight loss (5-7%) and higher retention of ascorbic acid during storage.
Packaging : Fruit bruising is a major problem during harvesting and packing. A 30cm drop is able to cause significant damage to the impact side of the fruit. Therefore, the packaging of fruits should protect the commodities from injury and water loss. Packages should also provide information about the product, including the grade, handling instructions, and appropriate storage temperatures when the product is on display. The cost of the packaging is important, including whether the container can be recycled or reused. The ultimate goal of packaging must lead to easier handling of the produce, a better quality and better marketable product.
Improved corrugated fibre board (CFB) boxes have been developed by Assam Agricultural University, Jorhat for long distance transportation of Khasi mandarin. The post harvest loss during transportation by truck (1000 km) was less than 15 in CFB boxes as against 10.82 per cent in wooden boxes. The cost of each box with an accommodation capacity of 128 fruits is Rs. 40-45 only.
Table 3: Specifications of CFB box.
| Parameters | CFB box |
| Internal dimension (L x W x H) in mm | 420x300x320 |
| Numbers of ply | 5 |
| Breathing holes | 18 nos. of circular holes (2 cm diameter) |
| Capacity | 128 nos. of mandarin |
| Stock load | 120 kg |
Advantages of CFB boxes:
- Minimum weight loss, least shriveling and reduced rotting due to mould growth during transportation.
- Better shelf life (25-30 days).
- Better marketability.
- Higher retention of ascorbic acid and sensory qualities.
- Longer shelf life of the fruits after transportation as compared to wooden and bamboo basket.
- Absence of bruising in the fruits during transportation.
- Easy to handle, good printability and economically viable.
Two pre harvest sprays with 0.1% Bavistan during August and September
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Harvesting fruits at optimum maturity (yellow orange/orange coloured stage)
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Sorting and grading
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Washing the fruits with chlorinated (100 ppm) water
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Drying (removal of surface moisture)
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Treatment of fruits with stayfresh wax (1 part wax + 2 parts water)
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Drying (removal of surface moisture)
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Packing in CFB boxes (128 fruits/box)
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Transportation by ventilated truck/train
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Wholesale market
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Retail market
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Consumer
Figure 1: Improved post harvest handling operations of Khasi mandarin
Storage: The basic objective of storage is to prolong the shelf life of a particular produce. If a produce is to be stored, it is important to begin with quality produce. In general proper storage practices include temperature control, air circulation and maintenance of space between containers for adequate ventilation and avoiding incompatible product mixes.
Table 4: Recommended storage temperature and relative humidity of orange.
| Temperature (°C) | Relative humidity (%) | Approximate storage life (weeks) |
| 3-9 | 85-90 | 3-8 |
| 6-7 | 90-95 | 45 |
Control of post harvest diseases:
Post-harvest decay of mandarin oranges due to infection of various pathogens (Botryodiplodia theobrommae, Colletotrichun gloeosporioides and Alternaria citri as pre-harvest pathogens) can be controlled to a great extent, if proper disease control packages are adopted. The stem-end rot caused by Botryodiplodia sp. and Alternaria citri are commonly experienced.
- Three pre-harvest spraying (45, 30 and 15 days before harvesting with Benzimidazole covering the whole canopy controls stem-end rot disease effectively.
- The post-harvest diseases caused by Penicillium, Aspergillus and Geotrichum spp. can be controlled by (a) washing fruits with chlorine water and (b) dipping them for 5 minutes in benzimidazole fungicides.
| Treatment | Storage temperature | Storage period (days) |
| Wax 3% + Benlate 350 ppm + PE | 11-19°C | 24 |
References:
1. Deka, B. C., Sharma, S. and Choudhury, S. (2008). Packaging system for long distance transportation of Khasi mandarin. Indian Journal of Horticulture, 65(4): 491-493.
2. Deka, B. C., Sharma, S. and Borah, S.C. (2006). Post harvest management practices for shelf life extension of Khasi mandarin. Indian Journal of Horticulture 63(3): 251-255.
3. Ghosh, S. P. (2007). Post harvest management of citrus. In: Citrus fruits. Directorate of Information and Publications of Agriculture, Indian Council of Agriculture, New Delhi, pp. 52-59.
About Author / Additional Info:
Scientist at ICAR Research Complex for NEH Region, Umiam, Meghalaya