SERVED
FRESH
Gautam
Bhattacharya discusses the best options available for packaging of fruit
juices and pulps, which promise to preserve the organoleptic properties
of the product
Juices
of fruits and berries were, in all possibility, the first beverages
that ancient human beings discovered, other than water. Wine, as we
know, was discovered accidentally and this was the first step towards
preparing fermented juices. Most fruit juices fermented so readily that
there was no commercial packaging required until, of course, the nineteenth
century.
By
the mid 19th century, the knowledge gained by the canning industry was
transferred to the bottling of fruit juices. Large-scale packing of
fruit juices started around 1925 in the US with packaging of tomato,
citrus and pineapple juices. Europe started commercial production of
packaged apple and grape juice post World War II.
Packaging
essentials
For
packaging of fruit pulp and fruit juices, there are certain chemical
considerations that need to be strictly adhered to. These are:
Acidity:
All fruits and their juices contain organic acids that can be detected
by taste and hence fruit juice products usually maintain an acidic character.
In most fruits there is one dominant acid, while the other components
of the product occur in secondary or trace amounts. Acidity is often
used as an indication of maturity, as it decreases on ripening of the
fruit.
Enzymes:
These
exist in all fruit juices and are also being used extensively for processing
the same. The most important enzyme, from the commercial point of view,
is pectolytic enzyme. Cloudiness of some citrus products is related
to pectin, which requires pasteurisation at a high temperature to inactivate
the enzyme before the juices are packed.
Vitamin
C (ascorbic acid): The
Vitamin C content of fresh fruits increases until just before ripening
and then decreases due to the action of an enzyme called ascorbic acid
oxidase. When the fruits are cooked, much of the ascorbic acid transfers
from the fruit tissue to the liquid juice and is oxidised.
Colour:
Permitted colours are mostly added to overcome the bleaching effect
of the sulfite which is used as a preservative, and to add to the appearance.
Flavourings:
These are added in the form of a syrup, which may contain fruits with
essential oils and other flavouring materials, preservatives, colouring
and artificial sweeteners.
Spoilage
and preservation
Yeasts
are mainly responsible for spoilage of fruit juices and pulps. Therefore,
to prevent the same, every living yeast cell must be removed from the
juice or suppressed by methods like pasteurisation, filtration and/or
preservatives.
Pasteurisation:
In
this method, the temperature of the fruit juice is raised to approximately
70-75oC and the heated juice is maintained at the high temperature for
a short period of time after which it is cooled before filling.
Filtration:
It
is normally used to achieve brilliance and clarity and to remove any
traces of yeasts.
Preservatives:
Depending on the legal requirements of the market and the flavour and
packaging considerations, the preservatives to be used are decided upon
and a maximum limit is listed for its usage.
Future
trends in packaging
The
fruit juice and pulp industry is going through a phase of radical change.
During the last few years, traditional glass and metal packages have
been replaced by paper-foilplastic aseptic packages and hot fill packages.
Recent advances in plastic extrusion technology show that high barrier
plastic packages will provide additional packaging alternatives in the
future, while continuously taking care of the critical oxygen barrier
properties of the package or packaging material that is used.
Glass
bottles and metal cans
Due
to suitable mechanical strength and barrier properties of glass and
metal, fruit juices and pulp are being packaged in glass bottles and
metal cans since a very long time. It has been observed that even when
stored normally under ambient temperatures, the fruit juice or pulp
remains organoleptically and nutritionally acceptable even after two
years of storage!
The
mechanical strength properties of these two materials allow thermal
processing of the fruit juice and pulp, and hot filling provides a virtually
limitless shelf life by avoiding....
contd.....
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