Preservation of Indian
pickle
Vijay
Kumar Shah
shahvk55@gmail.com
Mobile +91
99353 60033
WhatsApp +91 98397 84033
There
are two methods of preserving food namely.
1.
By
killing all microorganisms responsible by heat or by other means and then
checking further entrance of fresh organisms into the preserved product. In this case the product should be practically
bacteria and oxygen free.
2.
By
making the conditions, most unfavourable to the growth of microorganisms, so
that they may not multiply and thus damage the product. In this case there may
be living microorganism and oxygen may be present in the product.
The
first method is used for fruit and vegetable canning and second one in pickles.
Spoilage
in Indian pickle
Spoilage
of pickle is due to four main causes:
1.
Microbial – Off
flavour, softening, blackening
2. Biochemical – Blackening,
softening
3.
Chemical – Blackening,
metallic taste, off flavour due to metal or air.
4. Physical – Colour fading due to sun light.
Microbial spoilage
The
spoilage includes alteration of flavour, colour and texture of fruits such as
softening, blackening, slime production, ropiness, mushy texture, unpleasant
odour, bubbling etc. The colour changes from reddish yellow to brown, texture
from soft slimy to lumpy and mushy, unpleasant, sour, and oily odour develop.
There is surface growth too. These changes make the pickle unfit for
consumption.
Due
to acidic nature of pickle, major cause of microbial spoilage in pickle is
Mould and Yeast and not Bacteria. Putrefactive bacteria prefer a near neutral
pH, and they generally do not survive acidic pickle, unless the pickles are
very low in acid.
Growth
of yeast is indicated by characteristic estery odour and slimy growth on the
surface (Film yeast). It forms bubble also in pickle. Being anaerobic it
develops in whole pickle.
Mould
growth formed a white matted tuft followed by dark colour fruiting heads on
surface of pickle. It causes disintegration of fruits due to pectolytic
activity of certain fungi followed by fermentation and putrefaction. Mould
appears as surface growth as it is aerobic. So it does not grow deep down in
pickle. Among moulds Aspergillus niger was found to grow well in pickle containing
salt 10 – 20% and requisite proportion of spices.
Darkening
of pickle specialy at top: This is by a rection between tannin, iron and
oxygen catalysed by Polyphenoloxidase enzyme which produces dark compounds.
Tannin and enzymes are in fruit, iron may enter through salt, water, equipment,
dirt etc. Oxygen is from air which is in contact with the surface of pickle.
This is not common phenomena, only if there is more
tannin in the fruit, the pickle have chances of getting dark. The solution is
to prevent oxygen contact by oil layer or adding antioxidant like BHA or
ascorbic acid, or vacuum packing.
Softening of pickles – Mostly in mango pickle. It is mainly due to
pectolytic enzyme found in mango which is extracted in brine and causes
softening.
Colour fading: The red colour of chillie fades under direct exposure
to sunlight, and pickle looks dull.
Principals
of Preservation:
Salt, acid, spice, oil are the important ingredients
used in pickling. These substances when used in sufficient quantities, act as
preservatives. However none of these alone is sufficient to give self-stable
product, but a combination is used. According to Leistner (1955) there are 7
hurdles to hinder microbial growth and preserve food.
F
High temperature Heating
T Low temperature Chilling,
freezing
aw Reduced water
activity Drying,
curing, conserving
pH Increased acidity Acid addition or
formation
Eh Reduced redox potential Removal
of oxygen or addition of
ascorbate
Pres. Preservatives Sorbate, sulfite, benzoates,
c.f. Competitive flora Microbial
fermentations
If
the level of a particular hurdle is insufficient, it should be increased. If by
increasing it the food quality is affected an additional hurdle should be
considered. In pickle preservation a combination of many hurdles is used.
Salt
/ sugar (aw) – reduced
water activity by binding water.
Acid
(pH) - Increase in acidity i.e. reduced pH.
Eh
Oil / brine
covering, cutting off contact with oxygen.
Preservative
Addition of chemical
preservative + spices as preservative.
c.f.
(LAB), Fermentation by
LAB makes it unsuitable for other bacterial growth.
F
High temperature Pasteurization is
practiced in pickle in vinegar.
A
combination of high salt and high acidity coupled with anti- microbial
properties of spices prevent the spoilage of pickles by creating unfavourable
growth substrate for them.
Oil
helps by coating their spores and vegetative cells thus creating a barrier
between microorganisms and the water nutrient media. Oil on top helps to create
anaerobic conditions, and check the growth of aerobic microorganisms (aerobic
bacteria, moulds and yeast) which causes spoilage. Normally pickles are shelf
stable and if proper quantity of ingredients used they have long shelf life.
The
role of different ingredient in preservation of pickle is as bellow:
Salt: It helps by
binding water, making it unavailable for microorganisms. Different
microorganism requires different quantity of water for survival. By increasing
salt percentage in pickle, the types and thus number of microorganism that may
grow in pickle is reduced. However salt alone cannot prevent microbial spoilage
of pickle.
Acid: All
microorganisms have minimum and maximum pH between which they may grow. By
changing pH, the type of microbial flora that will grow in pickle will change. Pickles
are in general acidic in nature. Bacteria prefers near neutral pH, so pickle is
not their favourite media for growth. Some moulds and yeast may survive. By
increasing acidity their quantity and number is reduced. Again like salt acid
alone cannot make pickle sterile, but in combination with other ingredients it
helps a lot.
Acetic
acid
has considerably preservative effect but its efficiency is by no means total.
However, it is non-toxic, adds an appealing flavour to a food, and it has no
rival under these terms as a preservative. Since the bacteria that cause food
poisoning do not tolerate acetic acid, pickled foods are not likely to be
suspect in a poisoning incident – at least not in those cases where vinegar is
used in sufficient amount.
Spices: Many spices
produce antimicrobial compound that helps in preserving pickle. Although they alone will not preserve pickle, but they help
by reducing the quantity of salt and acid required for preservation.
As now there is a cry for chemical free food, considerable
attention has been directed
to the antimicrobial properties of spices. Analysis of their volatile
flavour and odour fractions,
known as essential oils, has frequently identified compounds such as allicin in
garlic, eugenol from cloves and cinnamon and cinnamic aldehyde from cinnamon
and cassia which have significant antimicrobial
activity. As a consequence, herbs and spices may contribute to the
microbiological stability of foods in which they are used.
Spices must be used at high levels to be
effective antimicrobials, but this will cause flavor issues in pickle.
In the
quantity used, spices do not have a major biocidal role. They are mainly used
as flavouring agent. However they have supplementary effect. Turmeric powder,
mustard seed or oil, ginger etc. apart from contributing flavour, help to
reduce even by half the quantity of salt needed for preservation. Some of the
spices affecting microorganism are:
Mustard:
Mustard and mustard oil produces antimicrobial isothiocyanates. It helps in
preventing growth of moulds. Traditionally
mustard powder is added as natural preservative.
Cinnamon: 0.3% cinnamon
is effective in preventing mould growth in pulp containing 16% salt, while 3%
cinnamon was required for pulp without salt. Less salt proportionately more
cinnamon is required to prevent mould growth.
Clove: 0.2% clove is
sufficient to prevent mould growth in pulp with 16% salt while 0.6% is required
in salt less pulp. Proportionately more clove is required as salt % goes down
in pulp.
Ginger : in 5%
quantity has bactericidal effect.
Turmeric
powder
: It is common to use turmeric powder at the rate 0.5 – 1 kilo / 100 kilo in
brined stock of mango or lime stored for conversion to pickle.
Ajawain: Thymol of ajawain destroys some pathogenic yeast.
Oil: It reduces
redox potential, by preventing contact of oxygen with pickle. Microorganisms do
not grow in oil. For their nutrient supply they depend on osmosis which is they
absorb nutrients from pickle in water soluble form. Oil coats their spores and
vegetative cells thus creating a barrier between microorganisms and the water
nutrient media.
Many
of them require oxygen for growth. Oil has
been used as an air-excluding ingredient since ancient times to keep foods from
spoiling.
Oil
on surface of pickle helps to create anaerobic conditions, and check the growth
of aerobic microorganisms (aerobic bacteria, moulds and yeast) which causes
spoilage.
However, as with other ingredient
oil alone is not a guarantee against spoilage.
Preservative: Chemical preservatives are not must in
pickle. A proper pickle can have long shelf life without any preservative. But
addition of preservative is common in commercial pickle. It covers up for poor
hygienic condition in factory or faulty handling after opening the bottle. It also covers up if the quantity of salt and
acid is not properly balanced in recipe.
The
plus side of using preservative is that with its help quantity of salt and acid
can be considerably reduced without affecting self - stability of pickle.
The
most widely used food preservatives in pickle is the Sodium Benzoate. It is
only effective at pH values low enough to ensure that substantial amounts of
the un-dissociated forms of the acid are present. It is well established that a
major reason for this is that the un-dissociated acid readily enters into the
microbial cell.
At
the same level of concentration SO2 is most effective
preservative followed by sodium benzoate, sorbic acid and sodium propionate
respectively. Adding salt helps in reducing preservative doses. Higher the salt
% Lower is the requirement of preservatives.
Generally,
in the presence of preservatives, the temperature/time values required to kill
microorganisms are lower than in the absence of preservatives. In other words,
microorganisms are killed more swiftly in the presence of most preservatives
than at the same temperature in their absence.
Reduced
redox potential (Eh)
That
is pickle with low oxygen. It can be achieved by
Physical
exclusion of air.
Residual
respiration and oxygen consumption by plant cells that quickly reduce the Eh
and make the environment anaerobic.
Addition
of ascorbic acid or other antioxidant.
Oxygen
removal by vacuum-packaging.
Cover
pickle with a layer of oil or brine. All pieces covered, nothing exposed to
atmosphere.
The
advantage of exclusion of oxygen is that Pseudomonads, fungi, and other
obligate aerobic microorganisms that may initially be present at high levels,
have little opportunity for growth. Some of these organisms are also
salt-sensitive, further reducing their ability to grow in this environment.
Improves
the colour of the products.
Antioxidant
The contact with oxygen causes two
problems:
Top blackening
Off smell of
oil.
Use of antioxidant will help in
preventing it.
If there is more tannin in fruit like
immature mango, Anwala etc., top blackening may become a problem. In such cases
Antioxidant like Ascorbic acid or Erythorbic
Acid may be mixed in pickle. Or other antioxidant like
BHA or TBHQ can be added to oil.
Chelate
Blackening – is also due
to iron which may enter through salt or equipment. In some places water also is
high in iron. Best is to avoid contact with iron. If water is high in iron it
can be treated. If not practical then a suitable chelating agent may be added
to pickle.
Pickles
in India can be classified into following categories.
Pickle in Oil
Pickle without oil
Sweet pickle & Chutney
Pickle in vinegar
Brine stock
If
proper precaution is taken, they will have long shelf life.
Pickle
in oil
This
is most popular type in India. Mango pickle, Lime pickle, Jack Fruit pickle,
Mixed pickle etc. Everybody is familiar with these.
In
India, acidic fruits like lime, mango, or gooseberry are pickled using 15 – 20%
salt. In these pickle, salt and acid acts as preservative. These are not
fermented by LAB or any other microorganism.
In
non-acidic fruit like jack fruit etc. and vegetables like turnip, cauliflower,
green chilli etc. some souring agent like lime juice, tamarind extract, vinegar
etc. or organic acids are added.
They
are made from fresh or salt cured material. Generally the raw material is not
cured in brine. The fruits and vegetables are mixed with salt and spices and
packed in jars. Edible oil is poured over the pickle to form a thick layer.
These
pickles should have following specification for long shelf life -
In
oil pickle salt and acid should be calculated on oil free basis i.e. Pickle
mass – oil content.
Salt
– over
12%, best is >15%.
Under certain
conditions it can be brought down to even 8%.
Acidity
– Titrable > 2%
of which
preferably minimum 0.5% should be acetic acid.
pH - bellow
3.5
Moisture
- bellow 50%
Oil
– sufficient to cover top
completely.
All
pieces should be fully submerged into gravy. Any exposed piece will attract
spoilage organism.
Analysis of a few typical Commercial
Pickle in oil is as bellow::
Type pH Acidity % Salt %
Lime 2.3 3.3 15.2
Mango 2.98 2.3 14.8
Green Chillie 3.31 2.3 14.5
Mixed 2.98 2.6 14
Preservative
– optional but commonly used in
commercial oil pickles. It should be in correct quantity and well mixed.
Normaly sodium benzoate is used. A little Sodium meta bi sulphite is also
useful and helps in making pickle bright.
Good
pickle is of typical reddish yellow colour, pleasant flavour, and firm texture
and does not show any surface growth.
Reduction
in moisture:
In
oil pickle less moisture means better shelf life. Some of the ways to reduce
moisture are:
Partial dehydration by exposing ready
pickle in glass jars to sun for several days.
Preserve pieces in brine and discard
brine. Use only pieces for pickle making.
Add solids like Gur,
Heat - salt, spices, oil etc. to
evaporate moisture in that.
Keeping
pickle in sun for 2 – 3 days as done in domestic condition improves flavor.
Pickle
without Oil
The
recipe of such pickle is more or less same as that with oil, only no oil is
added. Usually it is made from sour fruit like lime and mango. In these pickle
quantity of salt and acid should be on higher side and preferably chemical
preservative should be added. The pieces should be completely covered with
brine (Gravy) – nothing exposed.
Sweet
pickle & Chutney
FSSAI
classifies sweet pickle as chutney. Both are same.
Sweet
Mango Chutney:
It is generally exported.
A
value which may be called preservative index is important. The index should be
not less than 3.6%, which generally helps to preserve the product. In such
products, from organoleptic point of view, salt should not exceed 3 to 4%.
Hence by increasing the sugar content, it is possible to reduce the acetic acid
concentration. The quantity of acetic acid required may be calculated using the
expression:
Acetic acid in the whole product % = 
Analysis of typical Commercial Mango
chutney is as bellow::
Salt 2.3
+ 0.3
Acidity 0.7 + 0.8
Brix 58 - 60
pH 2.5 + 0.2
Sweet
Indian Pickle:
Sugar
alone to act as preservative should be 68.5%. If salt or vinegar or both are
present this quantity can be brought down. Thus if 4 – 6% salt is present and
1.5% acetic acid even 30 – 40% sugar will preserve. Analysis of a typical
commercial sweet mango chunda is as bellow:
Salt 1.8%
Acidity 1.1%
Brix 72 - 74
Inversion 30 – 50%
As there is high brix so there is danger
of sugar crystallization hence % sugar inversion is important here. Preservatives,
like sodium benzoate, may be added to extend the shelf-life of the product once
the jar has been opened.
Pickle
in Vinegar
This
is not common in India, but this type is very popular in western countries. Kimachi
of Korea, Saurkraut of Europe, Gherkin of Amerca are some of the examples. In
India radish, ginger, garlic, mixed vegetable etc. in Vinegar are made on
limited scale mostly in western India. The shelf life of these pickles is
dependent upon the vinegar and, where employed, on pasteurization. Vinegar contains
about 4% acetic acid.
Acetic
acid 3.5% alone will preserve and no organism will grow (3.5% of water content). As normal moisture is 55 – 60%, so 2% acidity
is sufficient. In vinegar pickle, vinegar
is main preservative. To avoid dilution of the vinegar by the water liberated
by the tissues of the vegetable are generally placed in strong vinegar of 10%
for several days before final packing. This treatment helps to expel the
intracellular gases and also prevents further dilution of vinegar in final
pickle.
Lactic Acid bacteria (LAB)
Fermentation
of foods also is a traditional and common preservation process. If lactic acid
bacteria are used for fermentation, acidification (low pH) contributes to the
preservation of pickles.
In
vegetable fermentation, the desired product quality and microbial stability are
achieved by a combination of factors such as salt, acidification, and so forth.
Bacteria in general prefer for their growth material with little or no acid.
The lactic acid bacteria (LAB), however, can grow in acid media and can also
produce acid through their action on the substrate. They
can grow in the presence of 8 to 10% salt. Advantage
is taken of these two factors in pickling. The growth of undesirable organisms
is inhibited by adding salt, while allowing the lactic fermentation to proceed.
When lactic acid is formed in sufficient quantity, the lactic acid bacteria
cease to function, and any further change in the composition of the material is
prevented. Normally these are packed in Vinegar.
LAB
fermentation is not common in Indian Pickle. However, it will improve texture
and flavour of vegetables with sugar like carrot, beet root; smelly vegetables
like radish, turnip; soft vegetables like cucumber etc.
Pieces
in Brine
In
India it is common to preserve fruits and vegetables in brine in season and
later convert them into pickle as per the market demand. Two methods of brining
are followed:
Dry
salting
– cut pieces of fruits and vegetables are mixed with 20 – 25% salt. By next
morning water from fruits and vegetables oozes out and forms brine. The fruits
shrink in volume due to exclusion of water and air from the tissues. The brine
stock should be mixed to make it uniform. As the volume of brine stock shrinks
so after a few days fill up the barrel up to top with cured material from
another barrel otherwise air space will help in developing bacteria and mould
to grow on top. In case pieces are not covered fully prepare brine of 20% salt
and 2% acidity and cover. This is practiced where fruit and vegetable contains
sufficient water like mango, Lime etc.
Wet
brining:
In this case fill up the barrel with vegetable and cover them with brine
solution up to top. If lactic fermentation is desired, start with 10% brine and
increase it to 20% gradually. As in case of carrot, radish, cucumber etc.
If
no fermentation is desired cover with 20% brine straightway. If fruits are non
-acidic like green chilli add 2% acid or lime juice in brine. Maintain overall salt
per cent of 16% and pH bellow 3.5 in the
pieces.
In
wet brining if fruits are floating as in green chilli, they should be pressed
down so that all is under brine, otherwise they will attract bacteria and fruit
flies. One may use wooden planks and stone for pressing or cover with plastic
sheet and weigh down it with water.
In
the presence of fifteen per cent salt and a certain concentration of acidity,
most of the harmful bacteria are inhibited and in time destroyed if allowed to
stand for a few weeks. If final
concentration of salt in the material is 15 – 20%, even LAB will not grow.
Some
people add chemical preservatives too to further safeguard from spoilage. In
brine stock by adding acetic acid and SO2 the quantity of salt could
be reduced. It has been observed that:
Mango slices in brine: Maximum number of yeast and bacteria are noticed in
10% brine. Mango slices kept in 15% salt permitted slow multiplication of yeast
but the slices were crisp and quality good.
Brinning condition for mango,
papaya, amla, bitter gourd, onion etc – A brine containing 10% salt + 0.3 –
0.5% acetic acid + 0.5% turmeric preserved the material in sound condition.
When
this method has been employed the vegetables can be kept in brine for more or
less an indefinite period provided the right storage conditions are maintained.
Precautions
should be taken to
save it from spoilage by aerobic microorganisms. 'The presence of salt and the
acid preserve the pickle by preventing the growth of putrefactive bacteria provided air is excluded. The common defects in stored
brine stock:
Film
Yeast:
During brining a white scum invariably forms on the surface of the brine.
Thickness of this scum varies from batch to batch and may be an imperceptible
film to a thick wrinkled layer. This scum layer is formed by wild yeast, which
will decrease the lactic acid formation during fermentation. So to minimize the
loss of lactic acid, this scum should be removed as soon after formation as
possible. If loss of lactic acid continues, there is a possibility of
putrefactive bacteria developing, making vegetables soft and slimy. However
addition of 1% acetic acid or even less will usually prevent the formation of
wild yeast.
Mould growth is
common on brine surface. It should also be removed as soon as formed. Addition
of 100 ppm SO2 will control it.
Blackening in pickle: It is characterised by the formation of black brine
and occurance of black or darkened areas on the outer surface of the pieces.
The black color of brine was found to be due to ferrous sulfide formed as a
result of reaction between the hydrogen sulfide (produced by bacteria) and iron
presnt in the salt. B. nigrificans isolated from black pieces, however
did not produce Hydrogen sulfide but produced a water soluble black pigment
which imparted the chareacteristic black colour to the brine.
Pasteurization
In
pickling of fruits and vegetables, thermal treatment is sometimes employed to
increase the microbial stability or safety of food products since vinegar
(acetic acid) alone or even combined with salt may be insufficient to prove reliable
long-term preservation. Pasteurization is quite common in fresh pack vinegar
pickle. In oil pickle it is not practised.
However many people specially obese and suffering from Hypertension
avoid pickle due to its high salt and oil content. Pasteurization can help to
formulate pickle with less salt and oil.
For
thermal processing, the pickle industry usually uses a procedure established in
the early 1940s that recommended an internal pasteurizing temperature of 74°C
for 15 min followed by prompt cooling.
However
for products with pH < 3.7, the slowest heating spot in the container should
achieve a minimum of 65°C for 16.7 min or 70°C for 2.1 min. Accordingly for oil pickle of < 3.5 pH pasteurization
at 700 C retort water temperature, 30 minutes dip. 10 minutes air cooling then water cooling is
sufficient.
Hygiene
The
initial microbial load of the raw material greatly influences the stability and
safety of food products. Good Sanitary condition should be followed.
Decontamination
of raw materials is effective. However it is not must.
Fruit
washing water- Should have 15 – 25 ppm
chlorine then plain water. Wash fruits and air dry.
Pickles
are in general self stable product with little preservation probelum. The
parameters mentioned above if followed will give pickles a long shelf life.
6.9.20
