Lesson 25

JUDGING AND GRADING OF BUTTER

25.1 Introduction

Butter may be judged from a commercial and from an individual standpoint. It is

important that the judge should become familiar with the quality of the butter as
required by the standard markets, and then judge the butter according to the demands
of the mass of the consumes, rather than according to the personal likes and dislikes.
In order to become a good butter judge it is essential that the senses of taste and smell
be acute even if one’s taste and smell are keen and sensitive, considerable practice or
experience is necessary. Almost anyone can tell good sample of butter from a very
poor one, but when it comes to differentiate between two samples, which are nearly
alike in quality, skill and experience are required. Most important in scoring butter is
to become thoroughly familiar with the ideal flavour of butter; then by repeated
comparisons of different samples of butter to this one ideal flavour, one will soon
become efficient in grading the butter. Various scorecards are formulated for sensory
evaluation of butter wherein maximum scores are allotted for various sensory
attributes of butter as shown in Table 25.1.
Table 25.1 Score card for butter

25.1.1 Desirable attributes of butter

—Package: should be attractive, neat, clean & tidy in appearance and have good
“finish” (smooth, attractive surface). All packages should be fastened firmly & neatly.

—Salt: it must be uniformly distributed & properly dissolved. If undissolved salt is

present, gritty effect is usually noticed in butter.

—Colour & appearance: a uniform light, pale yellow colour is liked most by the
consumers.

—Body & texture: the body of butter should be firm & exhibit a distinct waxy, close-
knit texture. When broken, the appearance of good quality butter should present
somewhat jagged, irregular, wrought-iron like surface. Butter should have smooth
“spreadability”.

Flavour: It should have a mild, sweet, clean & pleasant flavour & delicate aroma. A
characteristic feature of high-quality butter is that instigate appetite to crave more of
the product.

25.2 Manner of Judging

(i) Body: After the trierful of butter has been drawn out, the first thing to notice is the
aroma, and the body or texture of the butter. The butter on the outside should be
examined at once before it is affected by the temperature of the room. Notice its
colour, whether it is even or uneven, low or high. Determine to the appearance of the
butter whether it is greasy, fallow, spongy or sticky. Whether salty or salted
uniformly. Squeeze the butter with the thumb to ascertain the character of the body.
The aroma of the butter should also be noticed in connection with scoring the butter
on body and texture, as it is more pronounced immediately after the trierful of butter
has been drawn.

(ii) Flavour: It is impossible to describe flavours found in butter. However, there are
a few flavours which stand out more prominent and are more commonly met with
than any of the others. Good butter should possess a clean, mild, rich, creamy flavour,
and should have delicate milk, pleasant aroma.

Flat flavour is noticeable in butter made from unripened cream. Such butter is
otherwise clean, little objection is made to this kind of butter for ordinary commercial
purposes. The remedy is to ripen the cream a little higher with a proper ferment.
Rancid flavour is applied to butter which has an undesirable strong flavour. Rancid
flavour is the most common defect developing in butter on standing other flavours
developing in butter are, fishy stable flavour. Cheesy flavour is another characteristic
which is very common in butter. This condition develops chiefly in butter containing
little or no salt. It is claimed that it is due to the decomposition of the curd matter in
the butter.

Weedy flavor is quite common in butter. They are due to moisty to the condition of
milk previous to the manufacture of the butter. The remedy is to take the cows away
from the pasture in which weeks of the different kinds are growing, such as gartic,
milk onion etc.

Acid flavour is another common defect found in butter. It is usually due to the
improper ripening.

(iii) Colour: Colour of butter should be bright and even. The color preferred in Indian
markets is chiefly a high straw colour.

(iv) Salt: The amount of salt likewise depends upon the market and unless the salt
content is extremely high or extremely low, butter should not be criticized on account
of the amount of salt.

The chief thing to consider in judging butter on its salt content is the condition of the
salt. Notice whether it has been thoroughly dissolved and evenly distributed.

(v) Style: Style is the appearance of the butter and package whatever the shape of the
package, the chief thing to consider is that it is clean and neatly finished.

25.3 Grading of Butter

BIS has given an evaluation card of butter, which is shown in fig 25.1. The score
obtained after sensory evaluation of butter as per the card suggested by BIS, is used to
grade butter. As per BIS, grading of butter is as follows:

Quality Score Grade

Excellent
 90 or above A

Good B
80-89

Fair C
60-79

Poor D
59 and below

Fig. 25.1 Evaluation card for Butter

Uses of Butter: Butter can be used for direct consumption (table butter), in the
preparation of sauces, as a cooking medium, in the baking and confectionery
industries and in the manufacture of ice cream. Butter is also used in the manufacture
of butter oil and ghee and in the production of recombined milk.
Lesson 26
RHEOLOGY OF BUTTER

26.1 Introduction

Rheology is defined as the science of the deformation and flow of matter. The most
important aspect of rheology deals with the relationship between force and time on
one hand and deformation and flow of the material on the other.

Butter is an example of plastic materials that is upon application of force, the product
tends to yield or undergo permanent deformation. Butter texture is a critical factor in
determining functionality and consumer acceptance. It influences spreadability, taste,
mouthfeel, appearance, and its suitability for various uses. Spreadability is by far is
the most significant in relation to the table use of butter. Several methods have been
developed to determine the spreadability of butter in particular and texture in general.

Most of the tests used to characterize butter rheology are empirical in nature and
designed to imitate sensory perceptions for quality control operations. These are based
mainly on the principles of penetrometry, extrusion, and sectility and involve large
deformations which break down the material’s structure. The response of the material
to an applied stress provides an index for some consistency parameter which is
generally used to regulate a step in the butter making process.

Butter is a multiphase emulsion, consisting of fat globules, crystalline fat, and an

aqueous phase dispersed in a continuous oil phase. The textural properties of butter
are closely linked to their fundamental structures.

26.2 Butter Structure

Fat exists in butter in form of liquid fat and also in the form of intact globules. Liquid
fat makes the continuous phase in butter. Water droplets and air cells are dispersed in
this continuous phase. Some amount of fat is present as crystals. The number and size
of the fat crystals greatly depend on the temperature and the temperature history. A
considerable part of crystalline fat may be inside the fat globules because during
churning, liquid fat is extruded from the globules, mainly by spreading over the air
bubbles. But there are also crystals outside the globules and these aggregate to a
continuous network and may grow together to form a solid structure, which is mainly
responsible for the butter firmness. The microstructure of butter is shown in figure
26.1.

Fig. 26.1 Butter structure

26.2.1 Rheological properties of butter

The rheological properties of butter, to a large extent, are determined by the physical
state of milk fat. Hence, the consistency of fat can be modified in several ways like by
changing the temperature of cooling and working, and by changing the mechanical
treatment. Butter being an emulsion, ratio of solid to liquid fat, crystal dimensions and
polymorphic transformations play a major role.

26.2.1.1 Hardness and spreadability of butter

Butter hardness and spreadability are inversely related parameters and are two of the
most important aspects of texture. They have been the two most commonly measured
sensory properties as they greatly influence consumer acceptability. Butter possesses
poor spreadability at refrigeration temperatures, and poor structural stability at room
temperatures. At room temperature, butter also demonstrates oiling off and moisture
migration. The change in butter’s solid fat content between 10 and 20°C is very
pronounced, resulting in a very limited temperature range within which there is
desirable spreadability. At lower temperatures, more triacylglycerols crystallize into
the solid fat network. The degree of milk fat crystallinity is the largest determinant of
the rheological properties of butter. For easy spreading, butter should contain between
20 and 40% fat in solid form and, in general, butters with “yield stresses” below
roughly 125 kPa have satisfactory spreadability.

Butter texture depends on many interrelated parameters, and no single factor appears
capable of explaining its consistency. Milk fat’s fatty acid composition and positional
distribution influence the melting point, and therefore are of major importance. The
iodine value and average fatty acid chain length account for much of the variation in
butter firmness. A change in iodine value of 3% can effect a 50% change in firmness.
Winter butter is harder than summer butter because of seasonal variations in cow feed
which result in a more saturated fat overall during the winter.

26.2.1.2 Setting

Fat crystals, which are suspended in liquid fat, aggregate into 3-dimensional networks
because of Brownian motion and Van der Walls forces. This aggregation continues in
freshly made butter for months, resulting in increased firmness. The extent of this
setting depends on a number of variables, including composition, storage temperature,
storage time, the butter’s initial hardness, and the conditions during manufacturing.

26.2.1.3 Work softening

Butter may get softened by working. When the butter is subjected to extensive
working, its firmness is considerably reduced. The effect of working varies according
to the type and origin of butter. The greatest amount of breakdown occurs when the
temperature is around 10-15°C. If the butter is allowed to stand after working,
firmness gradually returns as discussed in setting of butter.
Lesson 27
MICROBIOLOGICAL ASPECTS OF BUTTER

27.1 Introduction

Microbiology of Butter reflects the micro flora present in pasteurization cream from which it is
made, water added at the time of salting of butter, Sanitary Condition of process of equipment,
manufacturing environment and conditions under which the product is stored. Intrinsic properties
of butter for e.g., pH salt content, uniformity of moisture distribution and droplet size, all impact
microbiological stability.

27.2 Micro-Environment of Butter

Micro-environment of Butter is unfavorable for growth of Microorganisms compared because of

the following compositional and structural differences.

27.2.1. Compositional differences

a) Fat content in butter is relatively resistant to microbial decomposition is present in

greater butter in butter (about 80%) compared to cream (except for high fat plastic cream)
b) Lactose which is readily utilizable by many of the microorganisms is present in lower
quantities.
c) Moisture content which is essential for microbial growth is present lower quantities
(<16%) in butter.
d) Salt in butter make its micro environment unfavorable for microbial growth.

27.2.2. Structural differences

The nature of distribution of water and fat in cream and butter makes their microenvironment
different. In cream water is in continuous phase and fat is in discontinuous phase, where are the
reverse in case of butter where water is discontinuous phase present as drops dispersed in fat. A
large number of water droplets are more than the number of Microorganisms in butter.
Moreover, unlike that in cream, Microorganisms cannot proliferate easily and spread in butter
because of the following reasons.
a) Water phase is separated by relatively resistant fat phase in butter. Molds and
Psuedomycelia forming yeast are able to grow and penetrate through the fat phase of
butter.
 b) Limited supply of nutrients in the H2O droplet in butter while in cream microorganisms
can grow in the continuous H2O phase having dissolved nutrients and migrate one portion
to the other.

27.3 Microflora of Butter

In spite of unfavorable conditions in butter for microbiological growth; since cream utilized for
butter making is pasteurized, the bulk of Microbial population in the final packet is contributed
by post pasteurization contamination during butter making. Microorganisms of the post
pasteurization contamination from utensils, H2O, air etc and belong to different groups of
bacteria such as psychrophilic/psychrotropic (proteolytic/Lipolytic), Mesophilic (Lactic and non
lactic acid) and spore forming bacteria. In case of yeast and molds, they may enter through aerial
route. The microflora of butter which belongs to above groups are summarized in the Table 1.

27.3.1 Sources of microorganisms in butter

Microorganisms which are present in Butter are derived from a variety of sources are explained
below.

27.3.1.1 Raw Material (Milk or Cream)

The quality of milk/cream utilized for production of Butter has a direct impact on
microbiological quality of the final product. Butter made from cream separated from EOD
(Every other day) collected farm bulk tank milk or bulk collected milk (refrigerated) was slightly
inferior quality with respect to flavor to butter made from daily collected can milk (cooled at
12�C). This is due to higher microbial number and activity in the EOD or bulk collected milk.
Highly heat resistant extracellular lipases which one secreted by Psychrotropic bacteria in such
milk may resettled in high free fatty acid content and also affect final composition and flavor of
cream and butter manufactured from it. This type of cream exhibited slow acid developed during
ripening due to possible adverse effects of liberated free fatty acids.

Both sour and sweet creams are generally used for manufacture of butter. Sweet cream contains
fewer nor organisms predominantly bacteria compared to yeast and molds. On the other side sour
cream contains larger nor of microorganisms sometimes up to a humdrum million per ml.
Sometimes the cream may be accumulated before churning into butter. During this period
microbial growth may occur. In some cases, because of the high initial population, a large
number of bacteria may survive in the pasteurized cream. Since the quality of cream has a direct
bearing on the microbiological quality of butter, these are a need for adopting the following
measures to maintain the quality standards of butter.
1) Hygiene production of milk and cream.
2) Proper quality control of cream before butter making.
3) Avoiding accumulation and high temperature (75�C)
Storage of cream before butter making
The following test may be carried out for quality control of cream for butter making:-
a) Organoleptic test
b) Acidity
c) Sediment test
d) MBR test
e) TBG
f) YGM count
As per the procedure laid down by APHA for milk and cream, the following standards as given
in Table 2 have been suggested for grading of cream on the basis of various microbiological
tests.
In India, no separate standard have been suggested for recommended for cream for butter
making, though the prescribed ISI standards are available market cream.

27.3.1.2 Equipments

The sanitary condition of various equipments used during butter manufacture determines to a
great extent the degree of contamination. Among these equipments, butter churn is
microorganisms� important source of contamination particularly in regard to psychrotrophic
organisms and yeast & molds, metals churns are advantageous from sanitary point of view but
still in many places, the wooden churns continue to be in use. These wooden churns are difficult
clean and sanitize since the wood surface is irregular which takes up water and subsequently
cracks, thereby, making the removal of solid particle difficult molds penetrates deep inside pores
and crevices of the wood and serve as a potential entry for contamination. The parts of
pasteurizers and allied units like pipelines, pumps, valves and coolers may be the other sources
of contamination.

27.3.1.3 Water supplies

During manufacturing of butter, water may be used for different purposes like to flush residual
cream form holding values into churns, for dilution of cream as break water, as chilled wash
water, for wet salting and for adjusting the moisture content of butter. In case of continuous
butter making process, water is used for washing of butter granules. The contaminated water
used one or more of those points lead to important sources for the entry of microorganisms. The
psychrotrophic bacteria known to cause spoilage in butter known to cause spoilage in butter may
gain entry into butter through such water supplies. The bacteria which are causing spoilage into
the final product through such water supplies are shown in Table 3.

Psychrotropic bacteria can grow extensively H2O in dairy tanks, when particularly when water
contains some organic matter and has not been efficiently chlorinated Coliforms and some heat
resistant Psychrotropic strains of bacilli and clostridia have been found to occur in natural water.
Psychrotropic counts of >100/ml & lipolytic counts of >10/ml are indicator of faulty chlorination
of H2O supplies. Total colony counts of> 250/ml (determined at 21 or 25�C) & Most probable
number (MPN) of > 10/ml (at 30�C) for Coliforms are indicator of unsatisfactorily quality of
H2O supplies. The effective measures to check contamination through water is chlorination of
H2O supply by adding suitable concentration of chlorine (1-5 ppm).

27.3.1.4 Air

Air is comparatively important source of contamination a butter plant than any other during
product plant. All plants don�t have a separate packing room or don�t maintain a high
standard of hygiene in butter packing room or don�t maintain a high standard of hygiene in
butter packing and printing room. Thus butter often gets exposed to air for long periods prior to
or during packing and get contaminated bacteria are the most predominant sources of aerial
contamination followed by yeast and molds. Suggested standard reported Bacterial counts of air
ranging from 11-132/ft3 & yeast & mold count of 4-26/ft3 during butter packing and printing
operations. Psychrotrophs are also encountered in the air of dairy plants. Molds spores remain
suspended in air and contaminant walls or wooden structures in the packing room, which can
serve as growth centres for molds. The main sources of aerial contamination in dairy plant
appear to be announcement of workers, fans, drains and dust from the surrounding areas.

Personnel

The persons involved in the manufacture and handling butter may introduce Microorganisms to
butter through contaminated hands, clothing, mouth, nasal discharge, sneezing etc particularly
doing packaging stage unhealthy persons, particularly those suffering from respiratory disorders
should not be allowed to handle butter. The personnel engaged in the packaging room should
follow the hygiene measures.

Butter color
The color used for incorporation into butter is particularly free from micro organisms. However,
if it is kept in open containers or is mixed with water in a unclean measuring containers, there are
chances of contamination of butter through butter color.

Packaging material

Normally, parchment paper is used for packing butter. This paper is usually received in a
satisfactory condition from the manufacturer but it may get contaminated especially with molds.
Subsequently during transportation or storage use of dry parchment and or air treatment of
parchment with hot brine or antifungal chemicals like sorbic acid/ potassium sorbate, Propionic
acid/ calcium or sodium propionate or benzoic acid/ Sodium benzoate may reduce the mold
contamination. Normally, a combined treatment of hot brine and sorbic acid (0.5%) for 24 hrs is
recommended.

27.3.2 Effect of processing on the microflora of butter

A number of factors like processing of cream, method of manufacture, working and salting and
conditions of storage affect the microflora of final product.

27.3.2.1 Effect of cream processing

The processing of sweet or sour cream like neutralization, pasteurization and cooling have a
pronounced effect on the microbiological quality of butter.

a) Neutralization of cream
The sour cream is neutralized before heat processing. The neutralization step may affect the
microbiological quality in the following manner.
The contaminated neutralization solution as a result of poor quality water used for dissolving
neutralizers may add microorganisms in cream. However, the contaminants entering at this step
may get killed during subsequent pasteurization of the neutralized cream.

(ii) Pasteurization

Cream is pasteurized at 71.1oC for 30 min (LTLT) or 90oC for 16 sec (HTST), which is more
severe treatment than that required for fluid milk. This leads to nearly 99% destruction of
microorganisms in cream. However, some of the cream borne Microorganisms are still carried
over to the butter due to the following reasons:
a) Resistance of certain microorganisms to survive pasteurization enables some of these
organisms like psychotropic heat resistant bacteria to cause spoilage in butter.
b) Improper pasteurization may results the survival of some spoilage causing
Microorganisms. Hence, a proper time-temperature combinatory for pasteurization
should be meticulously followed.
c) The practice of mixing raw cream with the pasteurized cream into the vat may also be
responsible for the subsequent transfer of microorganisms to the butter.
(iii) Ripening of cream

This step is applicable for making ripened cream butter. Ripening of cream affects the
microbiological quality of butter in the following ways.

a) There is considerable increase in the total bacterial count in butter involves direct
addition and multiplication of the added organism.
b) If the cultures used are contaminated, the considerable organism can also enter the
product.

c) In general, the acid production by butter cultures during ripening suppresses the growth
of spoilage causing organisms. (Eg. proteolytic and lipolytic pseudomonades)

Cooling /ageing of cream

After pasteurization, the cream is cooled to low temperature and it is help at this temp for ageing
(which helps in getting butter fat recovery in during churning). The temperature of cooling and
ageing generally followed under Indian conditions varies from 5-10oC for 2-4 hrs or overnight.
However, minimum holding is desirable in modern processing practices. If the cream properly
cooling/ageing conditions from satisfactory, there is little significance of such cooling/ageing
conditions from microbiological point of view. Bacterial numbers in pasteurized cream is
relatively lower and mainly thermophilic organisms are present which by and large appears to be
harmless in butter.

27.3.2.2 Effect of butter making

(i) Churning
Churning during conventional batch method of butter making involves vigorous agitation of
cream at 10�C. This step affects the microbiological quality butter in the following ways.
a) This process causes quantitative changes in microflora by breaking the bacterial clumps
and consequently increasing the total bacterial count.
b) Contamination of butter churn from extraneous sources may further add to the
microbial load in butter.
c) Major part of bacterial population goes to butter milk instead of butter during churning,
whereas rivers are true for molts due to this bigger size.

27.3.2.3 Effect of process for moisture distribution (working, printing and reworking)

The distribution of moisture droplet in butter is directly affected by working; printing and
reworking process the working of butter breaks the bigger droplets and brings about a uniform
distribution of tiny droplets, printing of butter, however, leads to aggregators of water into bigger
droplets and loss of free water from butter. Reworking of butter needed where moisture content
of lot of more and needs removal or when two or more lots of butter are to be mined. This is
preserved to have the same effect as the �Working� process on moisture distribution.

The nature of moisture distribution in turn affects the microflora of butter. The microbial growth
is restricted only infected droplets and a large number of tiny droplets in properly worked butter
remain sterile since migrations of bacteria through the resistant fat mass is difficult the
proliferation of organism in the infected droplet is restricted due to limited availability of
nutrients. On the other hand, in under worked or unworked butter, the bigger water droplets
support greater proliferation of microorganisms, thereby leading to butter spoilage. Based on this
mechanism, working of butter discourages microbial growth due to fines and uniform moisture
distribution whereas printing encourages microbial multiplication by creating bigger droplets.
Reworking has been observed to cause rapid deterioration of butter samples stores for long time
probably by renewed microbial activity.

27.3.2.4 Effect of salting

Salt, generally added to butter, is inhibitory to the growth of microorganisms. However, its
action is influenced by its concentration and its uniform distribution in water droplet which in
turn in dependent if butter is worked efficiently. The salted tiny droplets will contain high
concentration (>15% salt and hence prevent bacterial growth). If salt is not is uniformly
distributed, the bacteria will grow in regions where the salt concentration in moisture is low or
absent. Therefore, microbial growth is checked in the infected droplet in droplets in salted butter
and as a result microorganisms are more active in can worked or under worked salted butter than
in properly salted butter.

However some salt tolerant organisms for example particularly fluorescent pseudomonades can
grow in 3% salt concentration very few can grow in 5% salt and none can grow in 6% salt
concentration certain molds can also tolerate high slat concentration and grow on the butter
surface.

27.3.2.5 Effect of packaging

The addition of contaminating microorganisms in butter, at packaging stage mainly occur

through air and packaging materials, although the role of unhygienic packaging equipment
surfaces of personnel cannot be excluded.

27.3.2.6 Effect of storage

The temperature and time of storage have a definite effect on the microbiological quality of
butter. There is a wide range of temperature over and Microorganisms grow in butter. In tropical
countries like India, butter is stored at room temperature and conditions are congenial for the
microbial multiplication.

At low temperature storage, particularly in cold stores, the rate of growth of Microorganisms
decreases and only Psychrotropic organisms can multiply at such temperature. Coliform bacteria
die out during cold storage. Slight growth will occur in butter held at temperature below 0�C
and none is expected at -15�C. At this, temperature the total bacterial would be expected to
decrease slightly especially unsalted butter. Hence the ideal temperature for storage of butter for
keeping quality (12-18 months) is -12 to 18�C. Since the cooling rate of butter is slow due to its
high fat content, the bacterial counts will often increase especially in unsalted butter during the
initial stage of storage.

27.3.3 Microbial deterioration/spoilage of butter

Growth of micro organisms in butter causes a variety of color and flavor defects. Most of the
microorgansims in cream gets killed during pasteurization, the spoilage organisms mainly come
through post pasteurization steps and butter making. The defects in butter mainly attributed to
the presence of psychotropic bacteria (lipolytic & proteolytic), yeast and molds. The
psychotropic bacteria which are entering the product through unhygienic equipment grow during
low temperature storage. However, molds create problems and relatively high temperature as
prevalent India.

A. Color defects (Discoloration)

Discoloration of butter may be caused by bacteria, yeasts and molds. However major color
defect in butter are caused by yeast and molds.

Bacterial Discoloration

a) Black discoloration (like grease smudge) causative organisms: Pseudomonas

nigrificans. Due to butter stored at low temperature (optimum for pigmentation is 4�C
i.e. 15-20% salt concentration in the moisture droplets.

b) Fungal Discoloration: Butter gets discolored due to surface growth of molds and the
defect is also described as �moldy butter�. This is a major defect commonly occurred in
India since the ambient temperature storage condition encourages the growth of Fungi in
butter. Fungi growth also favored by higher moisture content and acidity. Some
psychotropic molds like Alternaria, Harmodendrum, phoma and stamphylium have been
appear to grow in butter ( unsalted) at low temperature (5�C) slightly growth @ -4 to -
6�C but not @ -7 to -9�C. Some common fungal discoloration frequently occurred in
butter areas follows

Discoloration Causative agent

 a. Mold discoloration

i. Black Cladosporium Eg. C. harbarum, Aspergillus,

Hasmodendrum,Alternaria, Mucor, Rhizopus, and Stamphylium

ii. Brown Aspergillus spp, and Phoma spp (muddy brown)

iii. Green & blue green Penicillium spp and Aspergillus app

iv. Orange& yellow Geotrichum candidum

v. Reddish pink Fusarium

�����������b. Yeast

i. Black Torula spp

ii. Pink Rhodotorula spp

B. Flavor defects: - Rancid & putrid or cheesy odor is the most common flavor defects in
butter. The other defects like malty, Shunk-like flavor yeasty may also occur in butter.

�����������a. Rancid flavor: - Butter gets rancid due to microbial,

enzymatic or chemical degradation of fat constituents. The fat hydrolysis in butter mainly
due to the activity of microbial lipases. Many of the lipolytic microorganisms are
psychotropic and are able to grow @ temperature slightly under 0�C and survive cold
storage @ -10�C. Some of the lipase producing organisms which can grow on butter is as
follows.

Bacteria Mold Yeast

Ps. fragi Geotrichism Candidum Candida

lypolitica

P. fluorescence Cladosporium butyri Torulopsis spp

P. putida Penicillium spp Rhodotorula

spp

Achromobacter lipolyticum Aspergillus spp Saccharomyces

fragilis
 �����������b. Putrefactive taint: - Defect is due to breakdown of proteins
by various Putrifactor organisms like Pseudomonas putrefacien, coliform, Flavobacterium
maloloris. The chemical compound which produced during the breakdown of protein is
closely related to isovaleric acid responsible for off-flavor. The causative organism enter
butter through unchlorinated water supplies and equipments (butter churns, Creat vats)

�������c. Cheese taints: - Cheese like flavors in butter is due to association

action of different gram negative rods shaped bacteria due to butter stored above 10�C.

�������d. Other flavor taints: -

i. Malty flavor: - is due to presence and growth of streptococcus Lactsis variable

maltigenes in cream. The formation of 3-methyl butanol in butter mainly
responsible for malty flavor.

ii. Shunk-like flavor: - Pseudomonas mephitica

iii. Fishy taint: Pseudomonas ichthyosmia, Geotrichum candidum and Yeasts

due to decomposition of lecithin to Trimethyl amine by microbes.

27.4 Public Health Importance

Butter is not an ideal medium for the growth of pathogenic or food poisoning organisms due to
high fat content, yet it may carry certain pathogen if contaminated during production, handling
and packaging. Certain pathogens have been found to remain viable for long periods in butter the
possible sources of pathogens in butter may be the cream itself (improperly pasteurized) or the
post-pasteurization contamination. Handler in the butter plant is usually the major sources of
such organisms in butter. Very few outbreaks of diseases or food poisoning have been reported
so far from butter. Staphylococcus aureus and salmonella have been encountered in butter.
Butter may, however, serves as a good medium for the growth molds including aflatoxins and
other Mycotoxins producers. Such toxins may cause serious health hazards in consumers. The
necessity of checking mold contamination and growth in butter.

27.5. Legal Microbiological Specifications for Cream and Butter

Consumer safety is paramount criteria for any food manufacturer or producer. To ensure the
safety to the consumer Food Safety and Standards Authority of India (FSSAI) introduce the Act
to monitor the food safety. It assigns the responsibility of food safety to the producer and
provides the necessary guideline, some chemical and microbial standards for the products like
butter are compulsory and every food manufacturing or dairy product manufacturing
organization need to follow these mandatory standards.

27.5.1 BIS standards for cream & butter

Beuro of Indian standards (BIS) has given the following standards for raw and pasteurized cream
i. Raw cream
Plate count/ ml (or g) Grade
< 4 X 105 Very good
4 X 105 � 20X 105 good
20X 105 - 1X 106 fair
>1X 106 poor

Coliform count /ml (or g) : Not more than 100 Satisfactory

ii. Pasteurized cream
The plate count/mL (or g) should not be exceeding 60,000 and coliform count/mL (or g)
should not be more than 10.
iii. BIS Standard for Butter
Standards and recommendations of Indian standards Institution for butter as follows
i) SPC. No standards have been suggested
ii) Coliform. The presence of more than 10cfu/mL butter is an index of insufficient
pasteurization or contamination of butter from external source like wash water,
equipment and other sources during manufacturing and packaging.
iii) Yeast & Molds (Y&M)
Y&M counts/ml Quality
Less than 20 Good
21-50 Fair
51-100 poor
More than 100 Very poor

USDA Specifications for Light Butter

Microbial determinations shall be made in accordance with the methods described in the latest
edition of Standards Methods for the Examination of Dairy Products, published by the American
Public Health Association. Samples shall be taken as often as necessary to insure microbial
control.
 Coliform -- Not more than 10 per gram.
 E. coli. -- Negative.
 Yeast and Mold -- Not more than 10 per gram.
 Standard Plate Count -- Not more than 1,000 per gram.

27.4.1 Sampling plans for cream and butter

The FSS regulations for microbiological criteria for the acceptance or rejection of sample are
lots. It sets out (FSSR, 2011):
v the food which must comply with the microbiological limits set in relation to that food;
v the micro-organism or group of micro-organisms of concern;
v the number of sample units to be taken and tested;
v the level of micro-organisms considered acceptable, marginally acceptable or
critical(depending on the sampling plan specified); and
v The number of samples that should conform to these limits.

The following terms, as used by the International Commission on Microbiological Specifications

for Foods (ICMSF), are defined and used in Standard 1.6.1.

n = the number of sample units which must be examined from a lot* of food. Most sampling
plans specify taking five sample units. However, when the risk has been assessed as relatively
high, a greater number of sample units is specified.
c = the maximum allowable number of defective sample units. This is the number of sample
units, which may exceed the microbiological limit specified by �m�. These are considered
marginal results, but are acceptable providing they do not exceed the limit specified by �M�.
m = the acceptable microbiological level in a sample unit. Sampling plans in which m=0 and c=0
are equivalent to �absent� or �not detected� reporting for the stated analytical unit size. In
most cases this is 25 g (e.g. not detected in 25 g).
M = the level which, when exceeded in one or more samples, would cause the lot to be rejected.
*A lot means a quantity of food, which is prepared or packed under essentially the same
conditions, usually:
� From a particular preparation or packing unit; and
� During a particular time ordinarily not exceeding 24 hours.
A lot of food does not comply with the standard if the number of defective sampled units is
greater than c, or the level of a micro-organism in a food in any one of the sample units Exceeds
M.

SI. Requirements Sampling Pasteurized Pasteurized Butter

No. Plan cream
1 Total plate count m 30,000/g 10,000/g
M 50,000/g 50,000/g
2 Coliform Count2 m < 10 /g 10/g
M 50/g
3 E.coli3 M Absent/ g Absent/g
4 Salmonella4 M Absent/ 25g Absent /25g
5 Staphylococcus aureus5 m < 10/ g 10/g
(coagulase positive) M 50/g
6 Yeast and mould count6 m - 20/g
M - 50/g
7 Spore Count: - -
(a) Aerobic7a m -
(B. cereus ) M - -
(b) Anaerobic7b m - -
(Clostridium
M - Absent/g
Perfringens)
8 Listeria monocytogenes8 M Absent/g Absent/g
Sampling Guidelines9 n 1-8 5 5
c 2 1-2, 5 2 1-2, 5-6
03,4, 8 03,4, 8
Storage & 0 to 4�C -18�C
transport
Sample 100ml or g 100ml or g
size
Lesson 28
BUTTER DEFECTS

28.1 Introduction

Defects in butter can be classified as defects related to flavour, body and texture and
colour. These defects may also be classified as defects related to cream and defects
related to faulty methods of manufacturing. All these defects are discussed in detail in
this lesson.

28.2 Flavour Defects

28.2.1 Cream-related off flavours

28.2.1.1 Feed and weed flavours and odours

The feed and weed flavours that appeals in freshly drawn milk are more or less readily
soluble or absorbed by the milk fat. They, therefore, are often more intense in the
cream than in the original milk and they appear in the butter churned from such
cream.

28.2.1.2 Cowy and barny flavour

This type of defect is due to contamination of milk with manure or stable air or both.
The Cowy flavour may be due to cows with unclean udders and to milking with wet
hands, to the handling and prolonged exposure of the milk and cream in poorly
ventilated stables.

Prevention

· Sanitation and cleanliness in the production of cream/milk such that there is no

· Contamination with manure, stable, dust and impure stable air.

· Milking with clean dry hands.

· Prompt removal of milk from the farm.

· Handling and storing milk/cream in a place free from stable air.

28.2.1.3 Unclean or utensil flavor

The task suggests contact of cream with utensils incompletely washed such as unclean
strainers, cream cans or separator bowls or faulty sanitary conditions of factory
equipments such as vats, pumps, conveyors, pipes, churns or packing equipments.

Unclean flavour may be the direct result of contamination of the cream with milk
remnants from unclean utensils or of absorption of their odours; it may also be the
indirect result of the activity of m. o. contained in the milk remnants of unclean
utensils.

28.2.1.4 Musty, smothered flavour

Causes

· When warm cream from the separator is held in a tightly sealed can, it often acquires
a peculiar smothered musky flavour and odour which may follow it into the butter.

· Storing of cream in a damp, musky smelling cellar, or other poorly ventilated room.

· Empty, sealed cans that have been out of service for a considerable period.

Prevention

· Prompt and proper cooling of the freshly separated cream.

· Storage in a properly ventilated place.

· Rinsing and clean cans before use.

28.2.1.5 Bitter flavour

Causes

· Abnormal physical condition of certain cows.

· Feeds and weeds.

· Protein and clean cans before use.

Some cows in late lactation regularly yield milk that has a bitter flavour.

Such feeds and weeds as lupines, ragweed, bitter weed, beet tops, raw posture, raw
potatoes, diverse decayed if feed stuffs, moldy oat and barley straws have been found
to be the cause of bitter flavour.

Bitter flavour also occurs due to the action of yeasts on proteins resulting in formation
of peptones and amino acids.
28.2.1.6 Yeasty flavour and odour

It is caused by the fermentation of the cream by certain species of yeasts (Torula

Cremoris and Torula sphaerica). In early stages of yeast fermentation of cream, the
odour usually is not unpleasant, aromatic and nutty character. Prolonged yeasty form
generally gives the butter a disagreeable bitter yeasty taste. In many cases, the yeasty
flavour and odour are accompanied by profuse foaming of the cream.

Prevention

i) Wash utensil after each use.

ii) Cool the cream to as low a temperature as possible as soon as it leaves the
separator.

iii) Do not allow the cans to stand on the station platform exposed to the sun in hot
weather.

28.2.1.7 Cheesy flavour

It denotes a very low grade of raw material. The cheesy flavour in such case is usually
of the cheddar cheese character. It is the result of very old cream that has been
produced and held under conditions that cause high acidity, curdiness and curd
decomposition.

28.2.1.8 Metallic flavour

The causes for this defect cab be classified as (i) contamination of cream with metallic
taste and (ii) action of certain species of bacteria.

The absorption of metallic salts by the cream is probably the most common cause of
metallic flavour in butter made from sour farm skimmed cream. This is attributable
chiefly to the condition of the utensils in which the cream is held on the farm and of
the cream shipping cans. Exposed surfaces of copper such as in copper vats, fore
warmers, pasteurizers, cream pipes etc with defective in coating also surface of alloys
containing considerable copper such as white metals are potential sources metallic
flavour in butter.

Metallic flavour is also caused by bacterial activity. The starters at certain advanced
stages of fermentation may and often do become metallic and may cause metallic
flavour in the cream inoculated with them. High acidity is practically always a factor
in the combination of conditions that produces this flavour defect. Cream rich in
butter fat, likewise, is more susceptible to the tendency to develop metallic flavour
than cream low in butter fat.

Preventions

i) Keep fat % less than 35.

ii) Encourage use of cans that are clean and not rusted.

iii) Keep all copper surfaces in plant equipment properly, tinned.

iv) Efficient CIP/Cleaning of equipments.

v) Do not over ripen the cream as don’t hold it excessively long.

28.2.2 Process-related off-flavours

a) Flat flavour

Butter termed flat in flavour lacks the pronounced pleasing flavour and aroma that is
characteristic of butter of superior quality.

Causes

i) Low content of volatile acidity, Diacetyl and other products that make up the
desired complex of desirable butter flavour.’

ii) Churning the cream sweet and without the use of starter.

iii) Profuse dilution of the cream with water.

iv) Excessive washing of butter.

Prevention

i) Proper ripening of cream.

ii) Avoiding dilution with water.

b) High Acid and Sour flavour

High acid flavour in butter is characteristics of butter made from cream received in
sour condition and that is not neutralized.

High acid flavour and aroma may also be caused by churning over-ripened cream or
by the use of over-ripe starter or by the use of high cream ripening temperature in the
presence of starter that lacks flavour organization and process acid only.

Prevention

i) Use of starter containing the proper balance of acid and flavour organisms.

ii) Ripening at optional temperature/time combination.

Butter with a typical sour flavour is usually the result of the presence of excessive
buttermilk. Such butter may also develop a curdy, cheesy flavour. This defect is
obviously due to insufficient washing and is avoided by washing the better
sufficiently to avoid in the butter.

c) Cooked or Scorched flavour

This flavour is characteristic of butter made from pasteurized cream. It is caused by

exposure of cream to high temperature.

* Cream properly pasteurized – cooked flavour in fresh butter which disappears

before the butter reaches market.
* If the temperature difference between heating medium – Scorched flavour and
cream is too high.
* More chances of scorched flavour when high acid cream is neutralized with lime
neutralizers.
* Heating the cream by means of direct steam pasteurization under pressure (with live
steam) and without metallic heating surface minimizes the danger of cooked or
scorched flavour, even when pasteurizing at high temperature.

d) Neutralizer Flavour

The tendency for this defect to appear and its intensity, depend largely on the amount
of neutralizer used. This amount of neutralizer depends on the initial acidity of cream
and the point to which it is neutralized.

The sourer the cream and the lower the point to which it is neutralized the greater is
the tendency for butter to show neutralizer flavour.

Lime and Magnesia neutralizer – Limy, bitter flavour

Soda - Soapy flavour

Causes

i) Reducing acidity of high acid cream to a very low level.

ii) Adding the neutralizer in too concentrated form, not distributing it quickly and
uniformly throughout the body of the cream or not giving the neutralizer sufficient
time to complete the reaction in the cream.

Prevention

i) Double neutralization

ii) Proper addition of neutralizer.

e) Oily or Oily Metallic Flavour

This defect is usually present in the fresh butter at the churn. The exact reactions
responsible for this defect are not a yet fully understood. However some factors are
identified modifying or controlling these factors can possibly prevent this defeat.
These factors are:

1. High acid cream

2. High fat content cream (more than 33% fat)

3. High temperature of pasteurization.

High temperature treatment of sour neutralized cream provides a combination of

conditions that is highly favourable to the production of oily metallic flavour in the
butter.

4. Prolonged holding after Pasteurization

5. Contamination of the cream with metallic salts.

There is no evidence that the presence of metallic salts like oxide cause this defect.
These oxides and salts are active oxidizers and catalizers so they intensify the defect.

Prevention

1. Vat pasteurization at temperature not exceeding 1600 F/30min.

2. If higher temperature must be used, churn as soon as possible.

3. Avoid cream contact with surfaces of copper/other metals.

28.2.3 Storage-related off-flavours

a) Surface Taint, Limburger or Putrid Flavour

The defect is called surface taint because it first develops at the surface taint because
it first develops at the surface. However the putrid flavour is not confined to the
surface, it rapidly involves the whole mass or package of butter.

The putrid flavour defect is also called as Limburger flavour suggesting the flavour
and odour of Limburger cheese.

The putrid flavour defect is mostly found in butter made from unripened or sweet
cream and light salt butter.

Causes

1. Protein decomposition by putrefactive bacteria Achromobacter putrafaceins,

pseudomonas and B. flourescens liquefaciens.

2. Contamination of butter cream after pasteurization. (Efficient pasteurization

destroys all putrefactive bacteria.)

Prevention

1. Efficient pasteurization.

2. Sanitation between pasteurizer and churn.

3. There should be no contamination from churn.

4. At the time of draining buttermilk it should be kept in mind that no buttermilk

should flow back to the churn as the bottom line is seldom clean and it usually
contains milk remnants with putrefactive bacteria.

5. Water supply.

6. Precaution in packing water.

b) Cheddar and Roquefort Flavours

* Found mostly in light salted and unsalted butter.

* Absent in butter held in commercial cold storage.
Cheddar cheese type flavour is caused by Proteolysis and lipolysis by several species
of bacteria.

Roquefort cheese flavour is usually associated with mold growth which involves both
proteolysis and fat hydrolysis.

Prevention

1. Good sanitation practices throughout the process.

2. Cream ripening with good starters.

Trends of flavour change

Rancid Flavour

It is a common flavour defect of butter made from raw cream. Rancid flavour in butter
resembles the pungent respecting taste and odour of such volatile fatty acids a butyric,
caproic and caprylic acids. It is caused by hydrolysis of fat which splits the butter fat
into FFA and glycerol.

Hydrolysis of fat is brought about by the action of m. o. or enzymes or both.

Prevention

1. Proper pasteurization

2. Efficient sanitation in plant

3. Clean water supply.

c) Tallowy flavours

The tallow flavour of butter resembles the flavour and odour of mutton tallow. In
severe cases of tallowiness, the butter usually also bleaches in colour. It is caused by
oxidation of the fat, involving the unsaturated fatty acids in butter such as the oleic
acid. Some investigations suggested that oleic acid combined with free glycerol
(produced by fat hydrolysis) forms glycolic acid ester of oleic acid. This product is
responsible for tallow flavour.

Causes
1. Air, light and heat

Exposures to air cause oxidation of fat. This is accelerated in the presence of light and
heat.

2. Metals

The presence in butter of certain metals, their salts or oxides, greatly hastens reactions
that lead to tallowy flavour. (Cu, iron)

3. Neutralization

Over neutralization aggravates the tendency of tallowy flavour as an alkaline

condition promotes fat hydrolysis and oxidation.

4. Diacetyl

Diacetyl is capable of causing tallowy flavour and bleaching of butter fat in the
presence of air. Excessive fortification with diacetyl thus causes tallowiness. Diacetyl
in butter should not be more than 4 ppm.

5. Absence of bacteria

Bacteria utilize oxygen in their metabolism and thus retard tallowiness.

Prevention

1. Uses if air and light proof liners and wrappers, treatment of wrappers with harmless
antioxidants such as Oat flour solution.

2. Surfaces should be properly tinned SS should be used.

d) Fishy flavour

Butter has a flavour and odour characteristic of fish. It is very serious defect of butter.

Causes

i) Certain feeds and feeding areas cause fishy flavour fish. It is very serious defect of
butter.

ii) Activity of microorganisms.

28.3 Defects in Body and Texture

i) Crumbly, Brittle body

The proposition of high and low melting fats present is controlled by the composition
of the butter fat and this is turn is primarily affected by the season of the year i. e. the
feed.

Winter – decreased amount of low melting point fats.

Summer – increased amount of low melting point fats.

Thus the winter butter fat is often accompanied by excessive hardness, crumbliness
and stickiness of butter. Winter butter fat contains large coarse fat crystals that will
continue to grow in size after manufacture, has a hard, friable, crumby texture.

Prevention

i) Avoid low cream cooling temperature and prolonged holding of cream at low
temperature.

ii) Chilling granular butter with cold wash water.

iii) Sticky Butter

This defect refers to butter that doesn’t cut clean. It sticks to knife or trier.

Prevention

i) Same as for crumbly.

ii) Churning immediately after cooling.

iii) Wash the butter with wash water at a temperature of 3 to 40 F below that of the
bottom.

iv) Weak Body

It lacks the desired firmness and standing up property.

Causes

i) Incomplete fat crystallization.

ii) Faulty adjustment of cooling temperature of cream or holding time.

iii) Low proportion of high m. p. glycerides.

iv) Greasy Texture

This defect occurs when butter is worked excessively while in soft condition. The
danger of greasiness is usually greatest in the case of abnormally rich cream
insufficiently cooled, and churned and worked while too warm.

Prevention

i) Proper cooling of cream.

ii) Chilling the butter granules thoroughly with very cold water (ice water) before
working.

iii) Leaky butter

Usually appears wet to the eye. When bored, it shows small droplet of moisture on the
plug and the back of the trier looks wet.

Butter suffers excessive shrinkage and loss of weight in storage.

Causes

i) Incomplete or improper working.

ii) Lack of fine dispersion of moisture in butter.

iii) Gummy butter

Butter when placed in mouth does not melt readily. It sticks to the roof of the mouth
and gives the impression of gumminess.

Causes

i) Presence of an excess of high melting triglycerides.

ii) Mealy butter

Mealiness is most likely to occur in butter made from sour cream that is improperly
neutralized with lime. Lime particles combine with the sour casein, forming minute
particles of insoluble calcium caseinate. In subsequent pasteurization these casein
lime particles contract and harden giving both the cream and butter, a disagreeable
rough graining as mealy character.

28.4 Colour Defects in Butter

The ideal color of butter ranges between a straw color and a golden yellow color. It
must be uniform churning to churning and the colour must be solid that is it must be
of the same shade or intensity throughout the body of the butter.

i) Bleached Butter due to oxidation of fat.

ii) Mottled – Unevenness of colour in the body of butter is shown in the form of
streaks, waves and mottles.

Causes

i) The whitish opaque dapples in mottled butter are due to localized sections of
innumerable, very minute droplets.

ii) Salting out action of the salt.

iii) Uneven working of different portions of butter of one and the same churning.

Prevention

i) Keep working rolls in good mechanical condition.

ii) Do not overload the workers/churn.

iii) Dissolve the salt completely.

Other defects

Yellow specks, white specks, green discoloration, Pink color and Moldy butter.