STUDY ON THE USE OF NATURAL FOOD ADDITIVES AND PACKAGING ON THE SHELF LIFE OF BHAPA DAHI
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Date
2016
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Publisher
AAU, Anand
Abstract
‘Bhapa dahi’ is a popular Bengali delicacy prepared at domestic level in West
Bengal. It is basically a steamed sweet dahi and is often called the ‘Indian cheese
cake’. Bhapa dahi is a product having high total solids (36.0 to 48.0 percent) based on
chakka (a base material used for shrikhand) and milk solids, has viable Lactic Acid
Bacteria (LAB, used as starter culture) and is characterized by a sweet and acidic taste
and having a gelled structure. The traditional recipe for preparation of ‘Bhapa dahi’ is
time consuming since it involves thickening of the milk by slowly condensing it,
setting the dahi using starter culture, followed by steaming it to form a gelled mass.
The reported scientific literature on Bhapa dahi is scanty. Fruit flavoured Bhapa dahi
,with extended shelf life, has a promising potential for its commercial development by
the Indian dairy industry.
The present investigation was carried out with the objective of enumerating
the viability of Lactic Acid Bacteria (LAB) in Bhapa dahi as affected by the steaming
treatment involved in its preparation. Consumption of viable LAB through fermented
milk product has been found to exert beneficial therapeutic effects in human body,
especially the gut health. Natural food additives (e.g spice extracts) have healthier
image by the consumers as compared to use of class II preservatives for extending the
shelf life of fermented dairy products. The essential oils of certain spices may not
only have a role in augmenting the flavour of fruit flavoured Bhapa dahi, but it may
help in extending the shelf life of product stored under refrigerated condition. The
type of packaging material used to contain the product can have an impact on its shelf
life. Hence, two types of packaging materials [i.e. polyvinyl chloride (PVC) and
polypropylene (PP)] were tested to evaluate their efficacy in extending the shelf life
of Bhapa dahi stored under refrigeration. Though FSSA specifications exist for Dahi
and Yoghurt, so far legal standards for Bhapa dahi is non-existing.
In the present investigation, mango flavoured Bhapa dahi was prepared
following the process standardized by Patel (2014) at Anand Agricultural University,
Anand. The current study involved checking the feasibility of adding few spice oil
extracts to the base mix (i.e. chakka plus condensed milk) to validate their
compatibility with mango flavour and its impact on shelf life extension of Bhapa dahi
under refrigerated conditions, packaged in two types of packaging materials. The
physico-chemical characteristics, textural quality, sensory quality and assessment of
microbial quality of the resultant Bhapa dahi were analyzed using standard methods.
The outlines of the research work as well as the salient findings for Phase-I to Phase-
IV are depicted below.
Phase-I: Studying the influence of steaming period in the manufacture of Bhapa
dahi on the viability of Lactic Acid Bacteria
The variables studies were steaming period of 9, 11 and 13 min. It is
recommended to subject the base mix (chakka and condensed milk) to steaming for a
period of 9 min in order to obtain Bhapa dahi having high viable LAB count as well
as desired sensory characteristics in the resultant product.
Phase-II: Selecting the essential oil of spice from amongst cinnamon, clove and
cumin oils which is most compatible with mango flavour in Bhapa dahi and
provides maximum shelf life extension
Cinnamon oil and cumin oil were tried out at levels of 0.02, 0.04 and 0.06
percent by weight while clove oil was tried out at levels of 0.04, 0.06 and 0.08 percent
by weight. Use of cinnamon, clove and cumin essential oil is recommended to be used
individually at levels of 0.02, 0.06 and 0.02 percent by weight of base mix
respectively in the preparation of mango flavoured Bhapa dahi for value addition to
product. Bhapa dahi made using spice oil at intermediate level of addition led to
product having significantly greater hardness value. Bhapa dahi made using clove oil
used at 0.06 percent level had the highest sensory acceptability compared to cinnamon
and cumin oils. Hence, in subsequent phases, use of clove oil as additive in Bhapa
dahi was studied as against control (without clove oil) product.
Phase-III: Monitoring the refrigerated storage changes in control and
experimental (containing spice oil) Bhapa dahi packaged in two type of
packaging materials
Bhapa dahi was packaged in pre-sterilized polypropylene cups and poly vinyl
chloride trays and stored under refrigeration (7±1ºC). Incorporation of cumin and
cinnamon oils (both added at 0.02 percent level) could yield Bhapa dahi having shelf
life of only 28 days; such was also the case with control product. However,
incorporation of clove oil at the rate of 0.06 percent by weight helped in extending the
shelf life of Bhapa dahi by a week (i.e. 35 days at 7±1ºC). During refrigerated storage
of control and experimental Bhapa dahi, there was a progressive increase in acidity.
Conversely, there was progressive decrease in the moisture content, pH and total
sensory score of Bhapa dahi with increasing storage period. There was a decrease in
the total sensory score of control product to the tune of 17.05 percent (up to 28th day);
the decrease in the score was to the tune of 18.88 percent in case of experimental
Bhapa dahi (up to 35th day of storage). The Standard Plate Count (SPC) and LAB
count showed an increase up to 14th day of storage, for both control as well as
experimental product; subsequent storage led to decline in the SPC and LAB count.
LAB count had the major share (95.5 percent) of the total bacterial count. There was a
gradual increase in the yeast and mold count (YMC) from 14th day for experimental
product (PP and PVC) and control product packed in PP whereas control product
stored in PVC showed growth from 7th day itself. Coliform was not detected in both
fresh as well as stored product. In terms of the type of packaging materials, PP cup
was superior over PVC tray with regard to restricting the mold growth and storage
stability of experimental product with regard to SPC (i.e. high LAB count).
Phase-IV: Computing the cost of experimental and control Bhapa dahi
The cost of 100 g serving size of control and experimental (containing clove
oil) Bhapa dahi was computed at ` 20.43 and ` 20.58 respectively packaged in PP
cup.
It is concluded that Bhapa dahi containing desirable (> 106/g of fermented
product) LAB count can be obtained by restricting the period of steaming to 9 min.
Out of three essential oils (cinnamon, clove and cumin) as natural food additives;
clove oil was regarded to be the best on the basis of sensory characteristics of mango
flavoured Bhapa dahi, when used at the rate of 0.06 percent by weight of base mix.
Incorporation of clove oil at 0.06 percent by weight extended the shelf life of Bhapa
dahi by a week (i.e. 35 days) as against control which could keep well under
refrigeration (7±1ºC) up to 28 days only. Opaque PP cups were found to be
marginally superior over transparent PVC trays during refrigerated storage of Bhapa dahi.
Description
Keywords
dairy science, dairy technology, study