Citrus

In the citrus processing industry, the raw juice, the peel residue and the seeds are the major product or by-products and from these sources a lot of industrial products are derivable.  The raw juice itself, single strength (natural) fruit juice (orange, lime/grapefruit, etc.), concentrated juice, citrus fruit powders and fruit (orange) flour are some of the major industrial products.  The peel residue, the pressed peel, citrus pulp and meal, peel oil, citric and lactic acids, brandy spirit, feed yeast, vinegar, marmalade, candied peel, citric pomade, etc. are some of the products. 

Products derivable from the seeds are seed oil and meal.  The level of sophistication of the citrus fruit utilization therefore depends on the technology available within the various citrus producing countries, and the dynamics of the cost of derivable products locally or internationally.

  Orange Juice Production (Single Strength): The basic industrial and domestic processing of citrus fruit for juice production is simple in that both processes (industrial and domestic) tend to ensure that the juice content of wholesome fruits are extracted without crushing the seeds nor allow contamination by the orange essence contained in the peel.  The following constitute the steps in the processing:

Cleansing: The citrus fruit e.g. orange the raw material is cleaned in a rotary washer, which is a propelling screw with a water injection pipe built in.

Warm Water Heating: Peeling of orange is easy if it is preparatory warmed by sending it through hot water.  Therefore cleaning takes place in hot water rotary brusher.

Peeling and Trimming:  Orange is peeled manually on a trimming table, where inferior fruits are eliminated.

Juice Extraction:- Peeled orange is fed into a hopper, at the entrance of which it is cut up into small fragments, which go into a cylindrical screen.  It is scrapped against the inner wall of the screen with a rotary scoop, so that the juice may be ejected from the holes of the screen and the waste from the outlet of the cylinder.  The juice then goes into a tank after been strained through a secondary cylindrical screen.

Preheating and Cooling:- The juice is heated to a temperature of 90^oC for inactivation of enzymes as well as pasteurization, after which it is cooled to a temperature of about 40^oC.  The pre-heater and cooler are designed for mutual heat exchange for effective utilization of heat.

Centrifugal Separation:  A centrifuge is employed in order to remove any pulp contained in the juice.

Desecration: In the course of the various treatments earlier discussed, a fairly large amount of air is bound to mix up with the juice.  It is for the elimination of such air that the juice is made to fall in a form of thin film, in cylindrical equipment, which is subject to a pressure of 60 – 100 mm/Hg on the inside.  Air is eliminated during the fall of the juice.

Formulation: This is done to adjust the concentration and the sugar contents of the juice. Addition of essence, colours, activators, citric acid, etc. may also be done.

Bottling/sterilization:  The juice is bottled and sterilization done at temperature of 90⁰C for 30 seconds.

Citrus production in Nigeria is still at its infancy. During the course of this survey, it was observed that more than 70% of the existing citrus orchards nationwide were planted with seeding plants obtained from uncertified sources. Majority of these orchards were at a stage of rapid decline in yield and needs to be rehabilitated.  This presents ample opportunity for nurserymen who can produce certified budded materials for the rehabilitation of these declining orchards.  The demand for citrus budding is on the increase and supply cannot cope with demand.

Also, most of the existing citrus orchards are in the small-scale category while only a few orchard fall into the medium and large holdings.  Most of the fruit juice processing industries are working at less than 50% installed capacity as a result of inadequate supply of raw materials.  Many of these industries have resorted to massive import activities of citrus concentrates.  This phenomenon highlights the heavy untapped investment opportunity in the area of citrus plantation establishment in Nigeria. 

Also a lot of investment opportunities exist in the area of fruit juice processing, as many Nigerians are aware of the health benefits of fresh fruit juices over the imported concentrates.

The industrial “waste” in citrus fruit juice production constitute between 40 – 45% in lemon and 50 – 55% (orange) as percentage of the original raw materials.  Such waste can be industrially used in production of seed oil and peel, lactic and citric acid, feed yeast, vinegar, wine, citrus pulp and meal, orange flour, peel oil, flavour nodes, etc.  These form a very big industrial enterprise in some countries like U.S.A.