Complete Dadih (yogurt)
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Transcript of Complete Dadih (yogurt)
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COURSE CODE : FST 4822
COURSE NAME : LABORATORY FOR CHEMISTRY AND TECHNOLOGY OF PLANT AND ANIMAL
EXPERIMENT NO. : 1 (DAIRY)
EXPERIMENT TITLE : PROCESSING OF DADIH
GROUP NO. : 1
GROUP MEMBERS :
TAN YIH YING 147732
SOON HONN KEONG
FONG PUI KUAN
CHOW SOOK YEE
OON XIAO YI
TAY PEI YIH
148820
149352
148485
149250
148201
HANITA HANIM MOHD ALI
MARDHIAH SUAIDAH BT SHAFIE
HANIS NADIA YAHYA
SITI NORLELA BINTI MOH SALLEH
149217
146573
150897
146106
LECTURER: DR. SEYED HAMED MIRNOSSEINI
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INTRODUCTION
Dadih is a dairy product produced by bacterial fermentation of milk. The bacteria used to make dadih
are known as "yoghurt cultures". Worldwide, cow's milk is most commonly used to make yoghurt, but milk
from water buffalo, goats, sheep, camels and yaks is also used in various different parts of the world. In
theory the milk of any mammal could be used to make yoghurt. Soya yoghurt, a non-dairy yoghurt
alternative, is made from soy milk; this is not an animal product, being made from soy beans.
Dairy dadih is produced using a culture of Lactobacillus delbrueckii subsp. bulgaricus and
Streptococcus salivarius subsp. thermophilus bacteria. In addition, Lactobacillus acidophilus, Lactobacillus
bifidus and Lactobacillus casei are also sometimes used in culturing dadih. The milk is first heated to about
80 °C to kill any undesirable bacteria and also to denature the milk proteins so that they set together rather
than form curds. The milk is then cooled to about 45 °C. The bacteria culture is added, and the temperature
is maintained for 4 to 7 hours to allow fermentation. (Coyle, 1982).
Dadih can be easily prepared at home. To produce a quart of dadih, a quart of milk is heated
(generally to 180 °F or 80 °C) and then cooled to approximately 110 °F or 43 °C. An inexact test for the
temperature is to test it with a finger: if the finger can be left in the milk for ten seconds, the milk is at about
the correct temperature. Once the milk has cooled, a tablespoon of yoghurt containing live active cultures is
added to the scalded milk and mixed well. The dadih is poured into a container and incubated for the desired
length of time. The fermentation time depends on the desired texture and tang in the final product. A shorter
period yields a slightly runnier product with a mildly sour flavor, while a longer period yields thicker and
tarter dadih. (Najmieh, 2007).
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Result:
A) Chemical Analysisi. Viscosity
Table 1: Viscosity of
Formulation A
Table 2: Viscosity of Formulation BFormulation B
1 2 Mean ±SDT (°C) 24.80 24.50 24.65 ± 0.2121Η ( mPa T) 47.20 35.80 41.50 ± 8.0610 [ pa] 73.16 55.46 64.31 ±12.5158
[1/s] P 1550.90 1550.90 1550.90 ± 0.0000
Table 3: Viscosity of formulation CFormulation C
1 2 Mean ± SDT (°C) 24.00 24.40 24.20 ± 0.2828Η ( mPa T) 20.20 19.70 19.95 ± 0.3536 [ pa] 31.26 30.63 30.95 ± 0.4455
[1/s] P 1550.90 1550.90 1550.90 ± 0.0000
Table 4: Viscosity of formulation DFormulation D
1 2 Mean ± SDT (°C) 24.20 24.60 24.40 ± 0.2828Η ( mPa T) 13.80 14.90 14.35 ± 0.7778 [ pa] 21.46 23.18 22.32 ± 1.2162
[1/s] P 1550.90 1550.90 1550.90 ± 0.0000
Formulation A1 2 Mean ± SD
T (°C) 24.50 24.40 24.45 ± 0.0707Η ( mPa T) 17.40 17.40 17.40 ± 0.0000 [ pa] 26.98 26.92 26.95 ± 0.0424
[1/s] P 1550.90 1550.90 1550.90 ± 0.0000
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B) Sensory Evaluation
Types of
Formula-tion
Taste
Mean±SD
Flavour
Mean±SD
Overall acceptability
Mean±SDG1
G2
G3
G4
G1
G2
G3
G4
G1 G2 G3 G4
A1 1 3 1 1.50±1.00
03 3 4 4 3.50±0.57
71 2 3 2 2.00±0.81
7
B2 3 3 2 2.50±0.57
74 3 3 3 3.25±0.50
03 3 3 3 3.00±0.00
0
C4 4 3 3 3.50±0.57
72 2 2 3 2.25±0.50
03 2 2 3 2.50±0.57
7
D2 1 2 1 1.50±0.57
73 3 3 2 2.75±0.50
02 2 2 2 2.00±0.00
0
Table 5: Sensory Evaluation of Dadih
Scale:1: Worst 2: Bad 3: Normal 4: Good
Formulation A Formulation B Formulation C Formulation D
Figure 1: Dadih of Different Formulations
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Discussion:
The dadih is prepared by using the acid method. The citric acid was used as the acidic medium. Citric
acid has various functions. It contributes refreshing taste to many foods and helps to prevent microbial
growth which can cause spoilage, and finally acts as a chelating agent, and its salts act as buffers that
stabilize pH (D.M.A Manan et al, 1998). Citric acid can introduce the sourness to the yoghurt. Besides, the
citric acid causes the textual changes by reacting with the casein protein in the milk to form coagulation.
Coagulation increases the viscosity of the dadih (Richard, 1962).
Generally, stabilisers or emulsifier such as gum are used during the manufacture of some dairy
product, but in dadih only stabilisers are added to the milk base. The primary aim of adding the stabilisers to
the milk base is to enhance and maintain the desirable characteristic in dadih such as texture and viscosity. It
also can refer as hydrocolloid and their mode of function in dadih includes first, the binding of water and
second promotion of an increase in viscosity. Thus, the molecules of the stabilisers can form a linkage
between milk constituents. Another factor which determines the level of stabilisers added to the dadih milk
is the percentage of milk solid present. The effect on the casein of some hydrocolloids such as gum that used
in experiment can stabilise the casein micelle (Tamime and Robinson, 1999).Tamime and Robinson (1999)
also explained that the binding water into milk base is achieved by stabiliser is it binds the water as water of
hydration. It also reacts with the milk constituents (mainly the proteins) to increase their level of water
hydration. Besides, it also stabilises the protein molecules in the form of a network that retards the free
movement of water. Therefore, the functions of hydrocolloids in dadih are as gelling or thickening agents
and stabilising agents.
According to the result, the viscosity of the dadih is decreasing from formulation B, C, A, and finally
to formulation D. However, from the experiment, the hydrophilic colloids bind water and consequently
increase the viscosity of dadih and also help prevent the separation of whey from dadih. Thus, it is able to
contribute the good coagulation property. The dadih formulation B had shown the highest viscosity in the
result while the formulation D shows the lowest viscosity. The formulation D is added 1 litre of water to
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dilute the milk powder and thus it consequently decreases the viscosity of the dadih. Besides that, the dadih
for formulation D also added the least amount of gum which is only 0.1% of gum compare to formulation B
and C. Theoretically, the formulation C supposing to have highest viscosity rather than formulation B
because it is added the highest amount of gum which is 0.5% as the stabilisers in the dadih which can
increase the viscosity. Yet, it shows the second higher viscosity in the result. It may due to the human error
during experiment. The inaccuracy in measurement of amount of gum would affect the texture and viscosity
of the dadih.
From the result of sensory evaluation, the flavour of formulation B was much more preferred than
the other three formulations and this is mainly due to the different amount of stabilisers added in dadih. The
taste of formulations B, C and D was rated equally higher than that of formulation A. The taste was mainly
contributed by the coagulation compounds present in the dadih which is the stabilisers and other compounds.
The gum is used to increased the viscosity and gel formation of the dadih. The overall acceptability of the
dadih made from formulation B was the highest rated followed by formulations C, D and A which is 3.00
followed by 2.50, 2.00 and 2.00 respectively. The formulation A get the lowest acceptability because there is
not stabilisers added to the dadih. The poor texture is produced in the formulation A dadih. Meanwhile, the
formulation D also gives the poor acceptability due to the use of milk powder in processing dadih. The dadih
produced by liquid milk will have smooth texture compare to the dadih produced using the milk powder.
The most beneficial quantity of stabilizer to add to dadih has to be determined experimentally by each
manufacturer. This is because excess amount of stabilizer would contribute rubbery texture and hard solid
mass.
Conclusion
In this experiment, the added citric acid helps to increase acidity of dadih, which helps to prevent
microbial growth, provide buffering capacity due to presence of ions in the solution and also introduce sour
taste to the dadih. From the result, dadih with the formulation D has the lowest viscosity while dadih with
formulation B has the highest viscosity. The viscosity is affected by the amount of gum added to the dadih.
However, there is human error that affects the accuracy of the result of viscosity. Dadih with formulation B
is supposed to have the highest viscosity. In conclusion, the different amount of gum used in the dadih
processing will have different effect on the physical property and sensory attributions of dadih. In this
experiment, dadih produced by using formulation B has the best overall acceptance compared to other types
of formulation.
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APPENDIX
Refferences
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1. Coyle, L. Patrick (1982). The World Encyclopedia of Food. Facts On File Inc.. p. 763. ISBN 978-
0871964175. http://books.google.com/books?id=iuPJlbBOst8C. Retrieved 11 August 2009.
2. D.M.A Manan et al, (1998), Lactose content of modified enzyme-treated dadih, Food Chemisty
Volume 65, Issue 4, June 1999, Pages 439-443
3. Najmieh (2007). A Taste of Persia: An Introduction to Persian Cooking.
4. Richard, F.D. (1962), Modern Dairy Cattle Management Prentice Hall-Inc- Dadih, pg. 238.
5. Tamime, A.Y. & Robinson, R.K. (1999). Yoghurt: Science and Technology (2nd ed.) Woodhead
Publishing Ltd. pp. 36-40.