ENGLISH PAPER
OBSERVATION
BIOTECHNOLOGY AT HOME YOGHURT, JUNREJO,
MALANG
Lecture :
Oktavia Widiastuti, M.Pd
By:
Ahmad Nuruddin Khoiri
(12620029)
DEPARTEMENT
OF BIOLOGY
FACULTY OF SCIENCE AND TECHNOLOGY
STATE ISLAMIC
UNIVERSITY MAULANA MALIK
IBRAHIM
MALANG
2013
ABSTRACT
Yoghurt or yogurt, milk is made by bacterial fermentation.
Yogurt can be made from any milk, including soy milk. But modern production is
currently dominated by dairy cows. Fermentation of the milk sugar (lactose)
produces lactic acid, which plays a role in milk protein to produce a gel-like
texture and smell unique to the yogurt. Yogurt is often sold as is, however
fruit flavors, vanilla or chocolate are also popular (Anonymous, 2007).
In the manufacture of yoghurt, there are several aspects of quality that need to be considered, are: Milk as a raw
material, raw milk yogurt can be used for full milk, skim milk, low-fat milk or fat
gain. Starter culture /
inoculum is a collection of microorganisms that are used in the production of
culture or cultured in dairy such as yogurt. Standarization of dry material, needed to obtain the structure of the gel and the desired consistency. Deaeration. Homogenization is necessary
to obtain a
mixture that is homogeneous so
that really can not happen cream or wheying separation during incubation and storage. Pasteurization to kill microbial pathogens and spoilage contaminants both contained in the
raw material. The incubation period is
important because the process darting through the stages of this process occurs
in milk fermentation by bacteria. Storage
techniques and cleanliness. Damage of
yogurt caused by microbes. Damage by microbes can
be determined visually, such
as the emergence of mycelium and spores, or can
be known from the beginning
of smell can also be distorted
and the basis of
microscopic examination.
TABLE
OF CONTENTS
ABSTRACT
................................................................................................................... 1
TABLE OF CONTENS.................................................................................................. 2
CHAPTER
I.................................................................................................................... 3
INTRODUCTION.......................................................................................................... 3
1.1
Background............................................................................................................... 3
1.2
Problems of study...................................................................................................... 3
1.3
Purpose of study........................................................................................................ 3
CHAPTER
II................................................................................................................... 4
DICUSSION................................................................................................................... 4
2.1 Explanation of
Yogurt............................................................................................... 4
2.2 Aspect of Quality in Making Yoghurt....................................................................... 5
2.3 Causes Damage to The Yoghurt................................................................................ 12
CHAPTER
III................................................................................................................. 14
CONCLUSION............................................................................................................... 14
BIBLIOGRAPHY........................................................................................................... 15
DOCUMENTATION......................................................................................................16
CHAPTER I
INTRODUCTION
1.1 Background
Yoghurt or yogurt, milk is made by bacterial fermentation.
Yogurt can be made from any milk, including soy milk. But modern production is
currently dominated by dairy cows. Fermentation of the milk sugar (lactose)
produces lactic acid, which plays a role in milk protein to produce a gel-like
texture and smell unique to the yogurt. Yogurt is often sold as is, however
fruit flavors, vanilla or chocolate are also popular (Anonymous, 2007).
Now often people like to consume yogurt. The
reason is because it is good for health. Yogurt
is fermented cow's milk. The content contained in yogurt the same as
cow's milk. Therefore a lot of people who do not
like cow's milk or cow's milk allergy by choosing to consume yogurt with yogurt
reason more delicious than cow's milk and yogurt have nowadays have a variety
of flavors.
1.2 Problems of the study
The problems of this
study, are:
1.
What’s
yogurt?
2.
How are
the spects of quality in making yogurt?
3. What are
the causes damage to the yogurt?
1.3 Purpose of the study
The purpose of this
study, are:
1.
To know the definition of yogurt
2.
To know the aspect of quality in making yogurt
3.
To know the cause of damage to the yogurt
CHAPTER II
DISCUSSION
2.1 Explanation of Yogurt
Yoghurt or yogurt, milk is made by bacterial fermentation.
Yogurt can be made from any milk, including soy milk. But modern production is
currently dominated by dairy cows. Fermentation of the milk sugar (lactose)
produces lactic acid, which plays a role in milk protein to produce a gel-like
texture and smell unique to the yogurt. Yogurt is often sold as is, however
fruit flavors, vanilla or chocolate are also popular (Anonymous, 2007).
Added Sugiono and Mahenda (2004), yogurt is a cultured milk
product, made by adding a culture of "good" bacteria in raw milk.
This can provide a good culture property or characteristic properties of
yogurt. These organisms will ferment and transform the milk sugar (lactose)
into lactic acid and create a certain flavor to the yogurt.
The term "yogurt" is derived from the Turkish language, namely jugurt or yogurut which means sour milk. By definition
yogurt is a product derived from milk that has been pasteurized and then
fermented with certain bacteria to obtain acidity, odor and flavor with or
without the addition of other materials are allowed (Surajudin, 2005).
Yogurt can be made from fresh milk or milk products with or
without added milk powder or skim milk powder. Source of fresh milk can be
derived from cow's milk, buffalo, goat or camel. But
of all the most commonly used cow's milk. Yogurt
is generally made from skim milk. Skim milk is milk that remains after a part
is taken partly or wholly cream in the separation process. Skim milk contains
all the nutritional components of milk are not separated, except fat and
fat-soluble vitamins (Surajudin, 2005).
2.2 Aspect of Quality in Making Yogurt
In the manufacture of yoghurt, there are several aspects of quality that need to be considered, are:
1.
Milk as a raw
material
Raw material in
the manufacture of yogurt is milk. Raw milk yogurt can be used for full milk,
skim milk, low-fat milk or fat gain. Whole milk good for raw materials, milk
powder without preservatives can also be used as a raw material. Raw milk is
milk that is to be in accordance with the quality. Raw materials must meet the
following requirements: low bacterial counts, does not contain antibiotics.
does not contain ingredients sanitiser, instead of colostrum, there is no smell
and no deviation bacterial contamination ophage.
Milk is a food
that is actually classified as sterile as in secretion in the udder, but on his
way to the nipple, the milk can be contaminated with a wide variety of
microorganisms. Some pathogenic microorganisms classified in the milk so that
the need for attention and special treatment are:
a.
Microorganisms in Milk Destroyer
The microbial quality of fresh milk is very important for
the assessment and production of quality dairy products. Milk can be said to
have broken if there is interference in texture, color, smell and taste of the
conditions under which the milk is no longer worth consumed by humans. Damage
caused by microorganisms in food often involves the degradation of nutrient
substances such as proteins, carbohydrates and fats, either by itself microorganisms
and enzymes are produced.
In general, the role of microorganisms in milk in this
case is psikotrof organism. Although most of these groups can be destroyed in
the pasteurization temperature, unfortunately, some kind such as Pseudomonas
fluorescens and Pseudomonas fragi can produce proteolytic and lipolytic enzymes
that are stable at high temperatures and can cause damage. Some of the species
and the descent of Bacillus, Clostridium,
Cornebacterium, Arthrobacter, Lactobacillus, Microbacterium, Micrococcus,
and Streptococcus can survive the pasteurization temperature and also able
to grow at temperatures in the cooling chamber, which in turn can cause damage
and spoilage problems in foodstuffs, especially milk.
b.
Pathogenic Microorganisms in Milk
Hygienic milk production as fast and precise handling, the
use of the means of production and means of storage and pasteurization
techniques have lowered the threat of the spread of disease through milk like
tuberculosis (TBC),
brucellosis, and so forth. Although still a debate among scientists, there have
been several cases of proven disease from consuming fresh milk or dairy
products made from cow's milk that is not pasteurized properly or poorly in
handling throughout the production process. Some pathogenic bacteria in fresh
milk and dairy products are still a concern at this time include:
o Bacillus
cereus
o Listeria
monocytogenes
o Yersinia
enterocolitica
o Salmonella
spp.
o Escherichia
coli O157:H7
o Campylobacter
jejuni
It should
be also disclosed herein that some types of fungi, most of the species of Aspergillus, Fusarium, and Penicillium can grow in the medium of milk and other dairy products. If conditions allow, this organism can produce mycotoxins substances that can be harmful to health.
Based
on that, we
need a handling raw milk prior to further processing into dairy products such as yogurt. If the milk is not the quality aspects dieprhatikan it will lead to lower quality of the product (yogurt), decay of food products (broken), missed on standard limits the number of microbes that make quality passes (off grade), and even the onset of illness from food poisoning or food.
2.
Starter culture / inoculum
Yoghurt starter culture or commonly called a starter or culture alone is a
collection of microorganisms that are used in the production of culture or
cultured in dairy such as yogurt or cheese. Starter cultures are cultured by
man (now generally performed in the laboratory) began when people started to
separate clumps of whey / curd or cream obtained from previous successful
fermentation process. And use it as an inoculant or a starter for the
manufacture of the product further. By using this starter culture produced
certain characteristics which can be easily controlled to produce the desired
fermentation product. In general, the primary function of this culture is to
produce lactic acid (lactic acid) of the sugar in milk (lactose). Moreover, culture can also be used to set:
o
flavor, aroma and alcohol production rate
o
the activity of proteolytic and lipolytic
o
inhibiting unwanted organisms
In general there are two categories of lactic starter culture:
a. Simple culture. Consists of one type of organism, or more than one which each number is known.
b. mixed culture. More than one type of organism, which each produce a specific character.
In the manufacture of yoghurt, starter / inoculum used was very influential on the products produced, among others, the formation of acid and flavor substances as well as other characteristics. Seeds or starter must be fresh if the seeds are already weak yogurt will be. To fully understand the principles of making yogurt is necessary to understand the stages of the process and its effect on the quality of the resulting product.
Yogurt culture has an important role in the process of
acidification and fermentation of milk. The quality of the final results of the
yogurt is strongly influenced by the composition and preparation of the starter
culture. The composition of the starter should consist of bacteria and
mesophilic tennofilik. Commonly used are Lactobacillus
bulgaricus with optimum temperature 42° - 45°C and Streptococcus thermophilus with an
optimum temperature of 38° - 42°C. Comparison of the amount of starter is
usually 1:1 to 2:3. During growth occurring symbiosis between the two types of
bacteria. Streptococcus thermophilus
will evolve more rapidly initiate the formation of lactic acid by fermentation
of lactose. This growth continues until reaching a pH of 5.5. They will also be
produced volatile compounds and release oxygen. These conditions provide an
excellent environment for the growth of Lactobacillus
bulgaricus. Proteolytic enzyme activity of Lactobacillus bulgaricurs cause decomposition of milk protein, produce amino acids and peptides that will stimulate the
growth of Streptococcus thermophilus. Lactobacillus
bulgaricus will also break down fats, producing fatty acids that give a
distinctive flavor to the final product yogurt.
In the manufacture of yoghurt usually there
are some problems that will
result from the use of a
starter who does
not meet the quality. For
example, with the
use of the same starter can continuously change
the ratio between the population of Streptococcus thermophilus and Lactobacillus bulgaricus and
eventually a mutation in derivatives
of 15 to 20. It
should be used in every manufacturing
of yoghurt new starter anyway.
Starter yogurt can
be made simply, can also
be obtained from the companies that
produce yogurt starter, starter bank or research institutions are usually called pure yogurt starter. Breeding pure starter mentioned
above, in the
company of making yogurt
in aseptic conditions and using sterile milk. So this should
be purely starter used
in the manufacture of yoghurt to produce products in
accordance with quality yogurt.
3.
Standarization of Dry Material
Standarization of dry matter needed to obtain the structure of the gel and the desired consistency. The addition of 3-5% skim milk can increase the nutritional value and improve the consistency of yogurt. The addition of stabilizer (eg 0.1-0.3% gelatin or agar or alginate) can improve the consistency and stability of the product. The addition of 4-11% sucrose and fresh fruit flavors of yogurt can change and thus more desirable, especially for people who do not like the sour taste. The addition of pieces can be done before or after pasteurization.
4.
Deaeration
The air contained
in the yogurt mix ingredients during the mixing process usually can’t get
out and can affect
the quality of the
final result yogurt. Therefore,
it should be done with
the deaeration pressure 0.7 - 0.8 bar at
70° -75°C. Deaeration can increase
the viscosity and stability
of yoghurt gel, while
also eliminating compounds that may
lead to the aroma and flavor that
is not desired.
5.
Homogenization
Homogenization mix ingredients after pasteurization is
necessary to obtain a
mixture that is homogeneous so
that really can’t happen cream or wheying separation during incubation and storage. Also to obtain a
stable consistency. Homogenization can also increase
the casein particles so
as to improve the consistency of the
gel during the
coagulation process.
6.
Heating treatment (pasteurization)
Pasteurization
carried out at a temperature of 85°C for 30 min or 95°C for 10 min. The purpose
of pasteurization is to kill microbial pathogens and spoilage contaminants both
contained in the raw material so as to provide a sterile environment and conducive
to the growth of the starter culture. In addition to whey protein denaturation
and coagulation so as to increase the viscosity and texture of yogurt.
7.
The incubation
period
Once the
process of starters finished the next process is the process of incubation. This incubation process is important
because the process darting through the stages of this process occurs in milk
fermentation by bacteria. In the
process of making yogurt requires warm temperatures. Not just warm but the
temperature needs to be maintained so constant, doesn’t go up or down too extreme during the incubation
process takes place. Rise and fall with the extreme temperatures can result in
yoghurt fermentation process is interrupted and failed to form.
The fermentation process is key
to the success of the production characteristics of the yogurt because the end
product formed during the fermentation process takes place. In general, the
fermentation is done at a temperature of 40° - 45°C
for 2.5 - 3 hours. However, temperature and fermentation time can be changed
depending on the type of bacteria in the starter culture used. Fermentation can
take up to 5 - 20
hours depending on the strength of the starter. In the fermentation process
will occur enzymatic hydrolysis of lactose into glucose and galactose.
Furthermore, glucose will be described through several stages of decomposition
to produce lactic acid. At this stage no change in the physical structure of
real milk, called prefermentation.
Galactose will not be used for glucose and lactose are still available for
fermentation. Therefore, the product still contained yogurt and lactose -
galactose residues. After a decline in the pH of the gel begins to form
gradually until it reaches the isoelectric point at pH 4.65. This process is called
primary fermentation. Gel formation followed by a change in viscosity. At this
stage also produced flavor.
In the fermentation process failure
often occurs partly because the incubation temperature is too low. Low
incubation temperature (room temperature) resulted in a slow rate of acid
synthesis (over 18 hours), while incubation at optimum temperature 40o-45oC
only need 2.5 - 3 hours.
The negative impact of the slow rate of acid formation may include, among
others, syneresis of milk serum (whey) that cause the quality is not so good
yogurt and lactic acids produced during the fermentation phase can’t be controlled. Therefore, it is
necessary to control the right temperature during the incubation process. In
addition to the temperature and time of incubation, hygiene issues also need to
be considered during the process of fermentation.
8.
Storage techniques
Cooling should be done immediately after the fermentation
so that no further acidification so that the product can be stored longer.
Products that have been finished and good, can be used as a starter in the
manufacture of yogurt next. Cultivated temperature decrease becomes l5° - 20°C can be achieved
within 1 - 1.5 hours. At this
stage it is the formation of flavor. Furthermore, the
ready-made yoghurt stored
at 5° - 6°C. For our own making
yogurt should be a maximum storage for 1 week. Cooling yogurt on the desired
acid levels can be done quickly so that the quality of the resulting yogurt is
more uniform.
Storage yogurt in principle is the preservation of the itself. Understanding preservation by Winarno and
Lakshmi (1974) is a technique or action taken by a man on a material such that the material is not easily damaged.
Further said that the aim of preservation inhibit or prevent damage, maintain quality and avoid poisoning. For fermented milk products, the acidic
nature enough to prevent damage by proteolytic bacteria or bacteria acid resistant (Frizier and Weshoff, 1978).
According Jawetz (1980), that storage at low temperatures is one way of controlling the breeding of
microorganisms. Further it is said that at very low temperatures germ activity stunted and almost no activity at temperatures
below freezing.
There are two things
to note in the storage of yoghurt are:
1.
Yogurt should not be exposed to sunlight.
2.
There should not be placed at room temperature, should be
stored in cold temperatures / refrigerator but also should not be placed in the
freezer. Yogurt should not be stored in the freezer for basic materials such as
milk yogurt that can be broken and that it would damage the yogurt.
Frazier and Weshoff (1978) says that the cold usually
resulted in a decrease in the number of microorganisms who live in a food, but
also a cold state can cause denaturation of the protein cells. Handling
yogurt after incubation
by freezing, do not show the effects of damage on the damage the starter culture yogurt or lactose activity (Speck and Geoffrion, 1980).
by freezing, do not show the effects of damage on the damage the starter culture yogurt or lactose activity (Speck and Geoffrion, 1980).
In addition to the quality of some important aspects to consider in the
manufacture of yoghurt there are also some things that should not be overlooked
is the cleanliness. Cleanliness is important, so you should use all the tools
that boiled in boiling water for 5-10 minutes. If hygiene is not maintained can
result in yogurt is not so, with the characteristics of a solid shape despite
not acidic, mushrooms grown on a solid surface in the form of black spots and
very sharp sour smell.
2.3 Causes Damage to The Yogurt
Some material is
considered defective if
they show irregularities consistency and texture of a
normal state. Normal material has
a thick consistency when the
situation becomes watery then
this is a sign of damage (Winamo and Lakshmi, 1974). Generally damage to the yogurt product is the deviation of the pH, odor rot and the incidence of whey and the occurrence of
gas.
Another form of damage is the damage caused by microbes. Damage by microbes can be determined
visually, for example onset of mycelium and spores, or can be known from the onset of odor distorted and can also be the basis of microscopic
examination. Damage often occurs in yogurt is the growth of mold on surface (Helferich and Weshoff, 1980). For example
yoghurt at pH 3.9 to 4.2 in the temperature of the cold storage when the contaminated will quickly be damaged due to the development of
mold and yeast.
1.
Damage To Room Temperature
Damage to the room temperature storage due to
damage growth The surface damage caused by the onset of yogurt and whey excessive.
Whey is a greenish yellow liquid separated from
yogurt (Helferich and Weshoff, 1980).
Damage caused by the onset of excessive whey shows
the magnitude of changes in the quality of yoghurt during storage temperatures room. At room temperature storage on the
third had already occurred damage with a very large decrease in pH well as the
total acid high.
2. Damage to the storage temperature of 10 °C
Damage at a temperature of 10 °C is generally caused by the
onset of fungi on the surface of the yogurt. The
survey results revealed that damage yogurt at 10
°C storage temperature began to arise in the week 3rd
storage.
Research has shown that yogurt can be said to be safe and
damage to the storage temperature of 10 ° C to 2 weeks of storage. Yoghurt is
immediately stored at 4-5 °C is still good for consumption after 7-10 storage
(Helferich and Westhoff, 1980).
CHAPTER III
CONCLUSION
3.1 Conclusion
Yogurt is a product derived from milk that has been
pasteurized and then fermented with certain bacteria to obtain acidity, odor
and flavor with or without the addition of other materials are allowed. In the manufacture of yoghurt, there are several aspects of quality that need to be considered, are: Milk as a raw material, starter culture / inoculum, standarization of dry material, deaeration, homogenization, heating treatment (pasteurization), the incubation period, storage
techniques and cleanliness. Damage of
yogurt caused by microbes. Damage by microbes can
be determined visually, such
as the emergence of mycelium and spores, or can
be known from the beginning
of smell can also be distorted
and the basis of
microscopic examination.
3.2 Suggestion
When making yogurt must always
be considered its aspects, in
order to produce a quality product.
BIBLIOGRAPHY
Farzier, W .C. and D
.C Wishoff . 1978 . Food Microbiologi
. Third Edition. Mc Graw-Hill. Book Company New York.
Helferich, W and D .
Westhoff. 1980 . All absut yoghurt prentice-Hall, Mc, Engel Wood-Cliffs . New
Yersey.
Speek, M .C. and J
.W. Geoffrion . 1980 . Lactose and
Starter Culture Surviver Inthat and
Frozen Yoghurt . J. Food Protection .
Surajudin. 2005. Yoghurt, Susu Fermentasi Yang Menyehatkan. Jakarta: AgroMedia Pustaka. 
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