This mobile fruit processing plant is a compact, movable juice extraction system designed for insertion on to the back of a moving heavy-duty truck. It is a fully integrated unit built on a skid mounted frame complete with non-slip durbar plate floor, canopy frame and heavy duty tarpaulin cover. The concept of operation is to be able to transport this facility remotely, over long distances to where ever required, for on-site processing in the growing area of fruit.
The mobile system is a simple, compact unit designed for processing a wide variety of fruits such as: mangoes, paw paws/papayas, pineapples, guavas, soursop and passion fruit. Provision can be made for the processing of citrus fruit such as oranges and an optional hydraulic press, complete with vegetable mill can also be included for the handling of hard fruits such as apples and hard vegetables, if required.
The mobile plant produces full-strength juice and has all the essential processes needed for juice extraction with the basic system comprising of: a rotary pulper/seiver (to extract juice and pulp from the fruit), juice reception/blending tanks and a juice pasteuriser unit. This unit is also supplied with large fibreglass tubs for manual fruit washing and handling and foldable stainless steel tables which are offloaded when stationary to enable manual inspection of the fruit and top and tail pineapples and halve the larger sized fruit.
The larger fruit need to be processed into smaller pieces prior to going through pulper/seiver on the mobile unit and therefore need to go through a specially designed fruit mill.
With the juice we would always recommend pasteurisation heat treatment to preserve the juice (rather than adding a lot of preservative chemicals). This involves heating the juice to a high temperature (85°C) for a short period of time to destroy bacteria’s, moulds and any unwanted micro-organisms that might be lurking in the juice. This improves the quality and also prolongs the shelf life of the fruit juice and avoids the use of artificial preservatives.
For the packaging, there are several options that can be considered. As the juice is being heated to high temperatures in the pasteuriser unit, the storage facilities/packaging used has to withstand hotfilling. It is therefore recommended either glass bottles or alternatively high-density polyethylene (HDPE) juice storage containers. These need to firmly sealed to prevent air contamination and then cooled. Processing unit also includes:
Non-citrus fruit – Up to approximately 500 - 1000kg/hr.
Hard fruit/Vegetables – Up to approximately 300kg/hr.
All fruit that are to be put through the mobile processing plant may be pulped using the preparation equipment provided with the unit. All the fruit must be ripe and of good quality and stringently inspected prior to being fed into the pulper/seiver. As many impurities as possible must be removed prior to milling and pressing, particularly the rotted or damaged fruit.
It is difficult to remove damaged or rotted fruit automatically therefore the most common method is to spread the fruit out on the conveyor where labour can be used.
Clearly the initial quality of the fruit determines the problems that may occur and the proportion that has to be removed, therefore minimum quality levels must be established for fruit purchased. In the fruit intake section - continued supply for any given fruit must be employed and a responsible reception controller must be employed to control this at all times.
Under ideal conditions average fruit weight would be 2kgs and the yield on average is 98 tons/hectare. For start-up purposes it is assumed that fruit will be 1.5kg average weight. On picking the crown is removed and he pedicule (stem) is cut as near the fruit as possible.
As the internal fruit temperature is direct sunlight can rise to 40°C the fruit should be picked early in the morning to minimise spoilage on transportation and storage. The fruit is collected in shallow perforated lug boxes which may be stacked without damaging the fruit. For short term storage the lug boxes may be stacked under a roof awning to prevent solar gain and occasionally sprayed with top spray of water which will evaporate and keep the fruit cool. The fruit should not be kept at temperatures below 10°C.
The pineapples are tipped onto the wash table where they are inspected to remove any defective fruit although with pineapples this should be carefully controlled at the picking stage.
The fruit then should be passed to the washer to remove soil, insects and loose scales followed by a drainage section to remove excess water. The pineapples are diverted onto a preparation table. The pineapples are topped and tailed and cleaved into longitudinal quarters. The cutting is done with stainless steel cleavers to avoid iron pick-up with cause’s discolouration. Quartering facilitates the efficient grinding of the fruit by reducing the fruit diameter and more particularly the fibrous core.
The quartered fruit is collected in the central conveyor and elevated to the fruit mill where is ground to a fine pomace. The fruit mill is mounted above the pulper/seiver unit and the pomace feeds directly in the sieving unit where the juice is separated from the coarse fibre. Both the fruit mill and the seiver have stainless steel contact parts. From the seiver, the juice is collected in a stainless steel reception tanks from which it is fed to the pasteuriser using a regenerating pump. The juice is heated to a pasteurisation temperature sufficient to destroy vegetative micro-organisms and enzymes. For pineapple juice it is necessary to heat to its maximum point to inactivate all the enzymes present. The pineapple juice yield will be up to 50% and is suggested that the waste fibre is recovered for cattle and poultry feed as it contains sugars, protein and fibre.
The soft ripe fruits are washed and then fed whole into the pulper/seiver where the pulp is extracted and the skins, stones and coarse fibre is removed separately. For a consistent product it is best to use one variety of fruit where possible and to avoid varieties with a pronounced turpene taste. Mango pulp needs acidification with citric acid prior to pasteurisation to bring the pH levels down and ensure a stable preserved juice.
The ripe fruit is washed, quartered and fed into the pulper/seiver to extract the pulp. The fruit may be used but should be adjusted to give a coarse cut to minimise damage to the seeds.
Ripe fruit of a consistent colour should be washed, halved and the bulk of the seed mass removed. The halves are then fed to the pulper/seiver machine to extract the pulp. Papaya pulp needs acidification with citric acid prior to pasteurisation to bring the pH levels down and ensure a stable preserved juice.
Ripe fruit is washed, shredded in the fruit mill and pulp extracted using the pulper/seiver.
The yellow passion fruit is washed, coarsely cut in the fruit mill and juice extracted in the pulper/seiver. For purple passion fruit, the fruit is cut at one end and seed ball reamed out and the juice extracted in the pulper/seiver.
Citrus Fruit - Orange
Provision has been made for processing citrus fruit and consists of a self-contained unit with feeder unit, with a squeezer mechanism and a separate holding tank for the juice. The reason for this self-contained unit is to ensure juice extraction without contamination from peels (oil). Oranges used for juice production must be of good quality and have good colour and flavour. Colour of the fruit will depend upon the variety. Unripe fruit will give a bitter taste, be low in sugar and have a low juice yield. Oranges are collected in stackable perforated lug boxes to minimise damage on transportation and storage.
The oranges should first be tipped out onto the inspection/preparation conveyor where the diseased, damaged and grossly undersized or oversized fruit need to be removed. The fruit is then passed through the fruit washer to remove adhering dirt and debris, rinsed and then drained to remove excess moisture. From this point the oranges then need to be put into clean lug boxes and fed manually into the orange juice extractor unit feeder for squeezing. Juice is then stored in a separate holding tank on the juice extractor unit itself and from there it would be pumped through to the pasteuriser.