Packhouse practices for mango

When the mangos arrive from the orchard, unloading should begin immediately in order not to delay further processing and the beginning of cooling. Weight of crates and fruits is recorded. A first quality control can take place simultaneously with unloading. A quality supervisor registers this data of the product. The stacking of the products received at the facility is done orchard-wise and clearly identifiable to maintain traceability.

De-sapping can already been done at an earlier stage, immediately after the harvest in the orchard. In other cases, de-sapping takes place in the packhouse. The stems of mango fruits are cut carefully to 0.5 to 1.0 cm. The fruits are held stem-end down while cutting the stem, and then placed stem-end down in racks. De-sapping, or latex removal, is necessary to prevent latex from mango stems dripping onto the fruit skin.

In this process the mangos are transferred into a dump tank, and water flume system, before entering the grading line. This transfer can be done manually or automatically, but in any case carefully in order not to injure the fruit. If de-sapping is done in the packhouse, it is highly recommended to wash the mangos immediately after de-sapping in order to remove any possible stains resulting from the latex. To avoid infestation with plant pathogens in the dump tank, the water must be sanitized. As a final step, the fruit must be rinsed with fresh clean water.

Depending on the import market, mangos may need to undergo a quarantine treatment to control infestations of fruit flies. This is to protect domestic agricultural production in the importing country against fruit flies from tropical regions. The most common quarantaine treatment for mangos is hot water treatment in which the mangos are submerged in hot water basins for certain periods. Hot water treatments are used as quarantaine treatment against fruit flies, as well as to reduce incidences of decay.

The goal of sizing is to ensure uniformity in size within the same package. The fruits must be dry before sizing starts. Drying can be done on a belt consisting of rolls where air turbines remove excess water from the washing step. The size of mangos is determined by the weight of the fruit or by count. Mangos below a certain minimum weight (for example 100 g) may not be suitable for the intended market.

The process of grading and classification should result in uniformity in origin, variety or commercial type, size and quality. Good quality mangos should appear full, firm and shiny. Make sure to sort out mangos with signs of decay and damages (such as cuts, bruises and latex stains). Always handle fruit carefully during this grading process. Mangos are classified into classes such as: class Extra, Class I and Class II. Examples of minimum requirements for all classes are that fruits must be clean and free from marked bruising.

Waxing may be done to reduce water loss and to obtain a shinier appearance. The need for waxing will depend on the requirements of the client. Then a food-grade wax is used, approved by the importing country. Fruits must be dry prior to waxing. The wax can then be applied by automatically spraying it on the fruit surface. Brushing during application helps to obtain an uniform application to the fruit. After waxing, the fruits pass through a forced air dryer.

The packaging needs to provide physical protection to the fruit. Therefore, a strong protective packaging is used. The cardboard boxes must be packed based on weight, ripeness and classification. Packaging requirements vary between customers and market segments, but usually the packaging is in single-layer boxes. The common varieties are often traded in 4 kg cardboard boxes with 7 to 8 mangos.

Filled packages must be stacked on a pallet and labelled with information including packhouse code, size/class, and batch number. Further the name of the fruit (mango) + variety, and net weight must be on each box label. The exact requirements can differ depending on local regulations and client demands. The completed pallets must be strapped well in such a way that the packaging cannot shift or fall. Often cardboard edge protectors are used to stabilize pallets. As soon as pallets are completed, they need to be moved to the cold storage.

A fast temperature reduction is necessary to remove field heat as soon as possible. Mangos should be cooled soon after harvest when their temperature is above the recommended cold storage temperature (usually 10-12 °C). Forced-air cooling is an effective tool to quickly bring down the fruit temperature and should be used when mangos are harvested under warm conditions. During this pre-cooling process, the fruit temperature should be checked regularly in the interior of the boxes, at the coldest and warmest spot of the pallet.

The optimal storage temperature for mangos depends on various factors such as cultivar, maturity stage and storage time. The temperature under which chilling injury may occur can also depend on cultivar. The best practice to follow in most case is to be conservative and avoid temperatures below 12 °C. Mangos should not be stored below their critical temperature, as chilling injury can occur that would result to risks of various quality problems, such as uneven ripening, increased susceptibility to decay and, in severe cases, flesh browning and poor flavour. Therefore, regularly check the temperature and quality in the storage room. A high relative humidity (85-90%) can further help to maintain quality.

Some packhouses (with importers) have ripening facilities. These are important for the ready-to-eat mangos and supply to supermarkets. The ripeness level at the start and temperature management are critical for the ripening. The exact ripening program is supervised by experienced experts. Special (forced-air) ripening rooms are used to achieve and maintain an uniform fruit temperature of, for example, 20 °C. The fruit is monitored to decide when to stop the ripening process. Exposure to ethylene can be an additional tool to speed up the ripening.

Proper cleaning and sanitizing of building and equipment is part of good packhouse practice. Besides maintenance as prescribed by the supplier, a good cleaning and sanitizing of equipment such as the grading line is necessary prior to use. Sorting belts must be clean and have smooth surfaces. All surfaces that could lead to bruising or puncturing of fruit should be well covered for example with impact absorbing foam.