Drying and waxingThen, after the fungicide bath, the fruit must be dried properly before waxing. Any wet fruit going into wax application system could cause the wax to break down resulting in erratic wax coverage on the fruit. Waxes are used to replace some of the natural waxes removed in washing and cleaning operations and can help reduce water loss during handling and marketing (Kitinoja and Kader, 20002). Waxes and coatings for polishing and improving shininess of citrus fruits, and waxes are available in various forms such as solvent waxes, aqueous emulsions, and resin solutions. Most South African citrus producers use citrashine natural wax with IMZ (500ppm in water bath), and chitosan and polyethylene-shellac treatment of citrus fruits are some of the commonly used postharvest coatings. Hydroxypropyl methylcellulose (HPMC) incorporated with natural wax founded to extend the shelf life of citrus fruits and improve quality (Armon et al., 2015).
Synthetic and non-edible coatings and waxes known to be harmful to research. As fresh produce is waxed, the wax coating must be allowed to dry thoroughly before further handling.Grading and sizingFruits are now ready for sizing and grading after being waxed.
The fruits are separated into different sizes and grades, or classes. The local market fruit is taken out and sent on a different packline that leads to where fruit are put into pockets, and exports fruit is graded into number of different classes. Grading occur after the fruit has been treated with fungicides and waxed and usually before the fruit is sized. In some packhouses, an optic sizer is used that can also detect fruit shape, colour and blemishes, but in most cases, sizers only separate the fruit into size categories, and it is up to graders to manually separate the fruit into classes (Kitinoja and Kader, 2002). South Africa producers categorize fruits into two major export classes, being class 1 and class 2. Fruit that has below class 1 are exported as industrial fruit or sold locally as fresh fruit and sent for processing. It is important for a grader to the minimum standards for all citrus types, because different markets have their own standards. The recommendation is that the grading table should be 0.
9 metres high above the tables. Exports fruit is normally sized mechanically after being graded.Labelling and gradingAfter fruit has been graded and sized properly, fruits are now ready for labelling. Markets require that fruits are labelled. In most packhouses, mechanical fruit labelling is used, but some cases packers stick the labels on by hand.
Export fruit are packed in the right carton, in the packing pattern that the market requires. The fruit may also be wrapped, if that is what the market wants. In some packhouses automatic packing machines are used. Cartons are the labelled, indicating the variety, grade, size, packing date, pack-line number, production unit code and packhouse code.
It is important to label cartons proper for good traceability. Sealed package significantly reduces incidence of Cl, decay and weight loss in lemon and grapefruit while TSS or TA did not get affected (Ismail and Menshawy, 1997) and therefore modifying the atmosphere around the fruit will retain its quality.Waxing and palletisingCartons are weighed before they are stacked on pallets to make sure that they conform to the minimum weighed requirements. This information is also used to make sure that trucks are not overloading. The packed cartons are stacked neatly on pallets, with the stacking pattern depending on the type of carton. Corner pieces are put in place and strapping is used to stabilise and secure pallets. For open-top cartons, securing sheets and pallet caps are also used.
Inspection, storing and dispatchingInspectors will now inspect the packed and palletised frit to make sure that it complies with the minimum requirements for export. In South Africa, the fruit inspection is done by Perishable Products Export Control Board (PPECB. After being palletised and inspected, the fruit is stored either in a cold room, or in separate area in the pack house. In the case of postharvest storage, mandarins are kept at 5-80C while oranges are kept at 4-50C with relative humidity of 90-95% (Kader, 2002). Prompt pre-cooling after harvest helps to prevent pitting and other peel disorders, such as stem-end rind breakdown and blossom-end clearing, helps to prevent the development of decay during storage, and slows respiration and water loss. At some packhouses, the pallets of fruit are packed directly into shipping containers to save harbour handling costs. Pallets are loaded onto trucks for dispatch to the harbour.
Alternatively, the pallets are loaded into containers, which are either transported on trucks or by rail.ConclusionThe majority of citrus fruits are consumed as fresh product, and this clearly indicates the importance to preserve the natural qualities of fresh citrus after harvesting. All packing house operations until the arrival of the products to the final market play a very important role in maintaining the quality characteristics of the fruits.