PROBLEMS IN JAM MAKING
Jam is a product made by boiling
fruit pulp with sufficient sugar to a reasonably thick consistency, firm enough
to hold the fruit tissues in position. It can be prepared from a single or two
or more kinds of fruits. Commercial Jams can be prepared from pieces of fruit,
fruit scraping and pulp. Apple, pear, sapota, apricot, loquat, peach, papaya,
karonda, carrot, plum, strawberry, raspberry, mango, tomato, grapes and
muskmelon are used for the preparation of jams.
Jam is a very common product made out of fruits and
vegetables that permit consumers to taste the fruits of their liking even
during lean periods or when the fresh produce is expensive. These products also
permit the diversification of the fruit used to avoid distress sales during the
production season and to minimize post-harvest wastages. This practice of
preparing Jam is very simple and could be attempted at household levels even in
rural areas if adequate food safety-related precautions are put in place.
Besides, there are several fruits that are not cultivated in large quantities
to permit large-scale processing. Still, these fruits are novel enough to
convert them into processed products like jam and present them to consumers.
The method of preparation of fruit jam is given in
our previous blog and can be seen through Method of Fruit jam preparation
Proper and well-processed jam can be stored for
6-12 months. But sometimes improper processing and storage leads to spoilage
of jam. Some of the problems in jam production are crystallization, sticky or
gummy jam, premature setting, surface shrinkage and graining and microbial
storage.
The problems in jam preparation are described below.
Crystallization
The crystallization of jam can occur due to a higher
concentration of sugar. The final product should contain 30-50% of invert
sugar. If the invert sugar percentage is less than 30% then the cane sugar may crystallize
and if its percentage is more than 50% then the jam will become a honey-like mass due
to the formation of small crystals of glucose. Corn syrup or glucose may be added
along with cane sugar to avoid crystallization.
Sticky or gummy jam
The high percentage of Total
Soluble Solid (TSS) in jam will cause gummy or sticky jam. This problem can be
solved by the addition of pectin or citric acid or both.
Premature setting
Premature setting of the jam
may occur due to low TSS and high pectin content in the jam. This issue can be
solved by adding more sugar. If sugar addition can’t solve the problem, then it
can be controlled by the addition of a small quantity of sodium bicarbonate, which
reduces the acidity of the jam and premature setting can be prevented.
Surface shrinkage and graining
Storing the jam at low RH (%)
and high temperature causes more moisture loss causing surface shrinkage and
graining.
Microbial spoilage
Moulds are the most
important microbes causing spoilage to the jam during storage. They are
destroyed if exposed to less than 90% humidity. Hence jam should be stored at
80% humidity. Mould growth can also be prevented by not sealing the filled jar
and covering the surface of the jam with a disc of waxed paper. Because mould does not
grow under open conditions than in closed spaces. Sulphur @ 50ppm in the form of
KMS (Potassium metabisulfite) can be added to the jam, but when one is taking
cans addition of SO2 is not recommended as it may cause blackening
of the internal surface of the can. Yeasts are not a serious problem due to the
high concentration of sugar.
Hence the proper processing and storage of jam can
be advised to reduce the problems in jam production.
