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The production of fresh citrus juices

Warren A. Kennedy

The Outback Juice Company. Hillston. NSW


The production of orange juice has undergone several cyclical changes since the inception of the citrus processing industry at the beginning of the twentieth century.

The first juice product was from hand squeezed oranges. It had a very short shelf life and a local distribution radius. Consumption was close to the point of production and very seasonal.

In the 1940s a giant step forward was made with the development of automated juice extractors which greatly increased the volume of juice available and lowered its cost. This, coupled with new processing technology, led to the rapid development of a processing/concentrating industry which allowed the consumption of orange juice to continue throughout the year without the cyclical interruptions of seasons and fruit availability.

It is from this point that today's world production and trade of FCOJ (Frozen Concentrate Orange Juice) has grown and upon which the world's juice converting industry has been based.

The 1990s Period

Until now, Australia has been a mass consumer of reconstituted FCOJ and not of fresh orange juice from retail outlets. Those who have wanted the fresh taste have hand squeezed their own oranges faithfully each morning with a dedication akin to those who punish the body with jogging.

Today the demand for a fresh orange juice has suddenly arisen as a part of the renewed consciousness of eating and living healthily. Australians are rediscovering the FRESH taste of orange juice, exchanging reconstituted juices for those which are freshly sqeezed.

Fresh Juice Production

Fresh juice production falls into several categories, each with its peculiar characteristics, which offer the consumer a number of choices. The common denominator here is that fresh juice is a more expensive product than those juices made from concentrate, not only because of the technical problems incurred but also because much of our concentrate is imported at a low price from nations which both subsidise the product and offer local people minimal standards of living.

In an effort to extend shelf life, fresh juice can be:

(i) pasteurised, often with resultant burnt tastes permeating the product;

(ii) preservatised;

(iii) both (i) and (ii) together;

(iv) chilled only.

The Hillston Operation

The Outback Juice Company at Hillston has taken a unique approach in an effort to gain its market share and acceptance, producing only a freshly squeezed product to which no external processes are applied or preservatives added.

The juice produced under these conditions is unique because it is still a living product which in turn limits its "life". This has required an innovative approach to juice production, as a minimum shelf life of 7 days is required for commercial acceptance.

The juice produced is a mixture of living cells, enzymes, volatile flavours and microorganisms. To maintain its inherent quality, both the respiration/ oxidation rate and the development of microorganisms and enzyme action must be inhibited. Fortunately this can be achieved with sustained low temperatures at all points of production.

The Process

Fresh oranges are placed in a cool room and chilled to 3oC. This is an expensive process considering only 50% of the chilled orange is juice.

The oranges are then run across a sorting table where substandard fruit is rejected. This is essential as a single bad orange can spoil a batch of juice, as opposed to those preservatised/pasteurised products which have a high tolerance of contaminated fruit.

After sorting, the oranges are washed and sanitised and proceed directly to the mechanical juice extractor which requires special adjustments to minimise the amount of albedo entering the juice (causing premature bittering).

The freshly squeezed orange juice is then stored in a refrigerated vat, in which the temperature is further reduced to 2oC.

Aseptic containers are direct filled with the chilled juice, palletised and placed into cold storage for despatch in refrigerated transport. All juice is then placed onto the retail shelf, up to 1000 km away, within 24 hours of squeezing.

As long as the product is treated by consumers in a manner similar to milk, a shelf life of 7 to 9 days is achievable.

Special Considerations

There are several special considerations necessary to successfully produce this sensitive product - all resolve around hygiene. All machinery which contacts the juice product must be sanitised with meticulous care both before and after each production run to prevent the accumulation and development of bacterial and yeast cultures. Regular bacteriological tests can identify an unseen problem area developing.

The entire factory area must be regularly sanitised to prevent the accumulation of yeast spores, bacteria and dust. In a similar manner the juice extractor must be cleaned of all peel and juice debris after each use to prevent yeast colonies from forming.

Waste peel and orange oils are disposed directly into trucks. This product is then fed to sheep.

Other Developments

New developments hold the promise of improved product and prolonged shelf life. Some of these are:

(i) deoxygenation of the juice and air space in the bottle to reduce the rate of product oxidation;

(ii) debittering of navel juice (removal of limolin), without pulp separation and pasteurisation. This will allow the use of fresh navels throughout winter and thus offer a better quality winter juice;

(iii) deacidification of juices to improve the taste of early season juices; essential, as most Australians, while having a sweet palate, decline the added sugar option to modify the taste. In a similar process to debittering, this is traditionally performed upon pulpless, pasteurised juice causing loss of fresh aromas and imparting a burnt sugar taste into the juice. A process is sought to achieve the above results using resin bead technology on bulk, pulpy juice;

(iv) new pasteurisation techniques are being investigated which will, with minimal temperatures, inactivate both enzymes and microorganisms, whilst maintaining the original flavour.

The fresh juice industry, whilst still in its infancy, is at the centre of innovative and exciting technological changes which will produce a better product.

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