In a professional kitchen, chefs and cooks keep on hand two
kinds of basic sauces:
flour based sauces:
White, Brown, Béchamel, and Tomato, and
Bearnaise, Hollandaise and
From these basic sauces, numerous variations can be made.
To make flour based sauces, the combination of butter and flour, called
roux is cooked together for thickening sauces. A sauce of average thickness is
made by allowing two tablespoons each of butter and flour to one cup liquid,
whether it is milk, stock, or tomato.
Butter and flour for brown sauces are
cooked together over low heat until brown.
For Brown Sauce, butter should
be stirred until well browned; flour should be added and stirred in butter
until both are browned before the addition of liquid.
The secret in making
a brown Sauce is to have butter and flour well browned before adding liquid.
To make brown Sauce, a slightly larger quantity of flour is necessary, as
by browning flour its thickening property is lessened, its starch being changed
When sauces are set aside or cooled for later use, put a few
bits of butter on top and cover with parchment paper to prevent crust from
Egg based sauces are emulsions of eggs, butter or oil.
Hollandaise, Bearnaise and mayonnaise. emulsion at work Sometimes eggs function
Try mixing oil and water, and you'll get, well, oil and
water. But with the addition of an egg yolk, oil and water-or fat and water-can
blend together into a smooth mix.
In Bearnaise sauce and hollandaise sauce,
melted butter and water form a creamy mixture. Tiny droplets of the butter are
dispersed in the water, creating a delicious combination.
A chemist would
call this an emulsion. A substance that helps two liquids remain in this state
is called an emulsifier. Egg yolks contain a number of emulsifiers. The same
applies to eggs and oil in mayonnaise
ASSURING SAFETY OF EGG YOLK-BASED
SAUCES AND SALAD DRESSINGS
by O. Peter Snyder, Jr., Ph.D.
Hospitality Institute of Hospitality and Management
670 Transfer Road,
St. Paul, MN 55114 USA
years, products prepared from raw shell eggs have been implicated in foodborne
disease outbreaks. It is now known that there may be the possible presence of
Salmonella enteritidis within the yolk of a small percentage of intact,
USDA-graded shell eggs. Food microbiologists and public health authorities have
named homemade mayonnaise, Caesar dressing, and Hollandaise and
Béarnaise sauces as items that pose risks of a hazard if prepared from
raw shell eggs. The safety of these products can be assured if the cook takes
specific steps, as presented in this paper, to reduce any possible Salmonella
spp. in raw eggs (egg yolks) to a safe level. This can be accomplished when
cooks use a preparation method for egg yolks that includes the addition of acid
and a pasteurization step that provides a 100,000-to-1 CFU/g (5D) Salmonella
reduction before the acidified/pasteurized egg yolks are used in the
preparation of these products. Recipe formulations, calculations, directions
for preparation, and pH of final products are given.
Raw eggs are a functional ingredient in many sauces and salad
dressings. In the past, the FDA considered the contents of whole, uncooked
shell eggs to be pathogen-free and did not consider the contents of fresh eggs
to be a high risk food. However, possible contamination of intact shell eggs by
S. enteritidis was recognized in Europe and the United States during the latter
1980s when it became known that this pathogen could be transferred from the
infected ovaries of laying hens to the egg yolk before the shell was formed.
USDA grading of shell eggs does not detect the presence of this pathogen.
Today, a small percentage of raw shell eggs are contaminated, perhaps 1 in
10,000. This is true throughout the U. S. Unfortunately, one cannot look at the
intact shell egg and have any idea about its safety. Therefore, food
microbiologists and public health authorities have named homemade mayonnaise,
Caesar dressing and Hollandaise and Béarnaise sauces as items that pose
risks of a hazard if prepared from raw shell eggs. However, the safety of these
products can be assured if the cook takes specific steps as presented in this
paper to reduce any possible Salmonella spp. in raw eggs to a safe level. This
can be accomplished when cooks use a preparation method for egg yolks that
includes pasteurization which provides the same 100,000-to-1 CFU/g (5D)
Salmonella reduction, or greater than is specified for cooking hamburgers.
To prevent foodborne illness, public health authorities recommend: (1)
using pasteurized intact shell eggs (available in only a few areas of the
U.S.), (2) using commercial liquid egg products pasteurized according to USDA
specifications (USDA 1969) that are normally only available frozen, in large
containers, (3) purchasing supplier-certified, salmonellae-free eggs (which are
available from only a few suppliers), and (4) cooking eggs until all parts of
the egg reach a temperature of at least 145F (63C) for 15 seconds according to
the FDA 1995, 1997 Food Codes. (This really is not an adequate pasteurization.)
None of these options are practical for a normal retail food operation
preparing fresh sauces and dressings in small quantity.
hazard can be eliminated if certain precautions are taken, such as those used
in the commercial preparation of mayonnaise. Acid ingredients in mayonnaise, if
in sufficient concentration or amount, can eliminate salmonellae from raw egg
yolks if given an adequate amount of holding time at room temperature after
manufacture. Federal regulations assume the presence of salmonellae in raw eggs
used for salad dressings and require that commercially manufactured dressings
such as mayonnaise and salad dressing made with unpasteurized eggs must have a
pH of less than or equal to 4.1, an acetic acid level of the aqueous phase of
greater than or equal to 1.4%, and a holding period of 72 hours before the
product is shipped (CFR Title 21 Part 101.100 and 169.140). These conditions
were established to assure destruction of Salmonella and were based on studies
of Wethington and Fabian (1950). The use of unpasteurized eggs in mayonnaise or
salad dressing by commercial manufacturers was discontinued in the early 1970s
and they began using USDA-certified, pasteurized eggs. However, there still may
be low contamination of these pasteurized products with low levels of
Salmonella spp. Therefore, the acetic/citric acid level in these products
remains critical. Commercial mayonnaise in the United States produced in
accordance with the FDA Standard of Identity actually contains enough acid to
destroy Salmonella spp. and inhibit the growth of other foodborne pathogenic
bacteria such as Listeria monocytogenes (Smittle, 1977; Glass and Doyle, 1991;
Erickson and Jenkins, 1991; Radford and Board, 1993).
This paper will
describe a simple egg yolk pasteurization method that incorporates this
acid-safety concept. Restaurant chefs and cooks in homes can use this method to
assure the safety of sauces and dressings made from fresh egg yolks. This
method can be used to prepare a few pasteurized egg yolks in advance for use in
sauces and dressings throughout the day as well as for the immediate
preparation of these items.
Method for Controlling
Salmonellae Contamination in Egg-Based Sauces and Dressings
The simplest method for controlling microbial contamination and minimizing the
risk of foodborne illness in a kitchen is the application of heat.
occurs when products are pasteurized. However, heating fresh eggs (whole or
yolks) to temperatures sufficient to decrease microbial hazards for emulsified
salad dressings and sauces has not been thought by cooks to be possible. This
is because most cooks know that when eggs (whites and yolks) are heated above
150F (65.6C), the egg proteins solidify and become hard. When egg-thickened
sauces are heated excessively, the emulsions break, and the sauces curdle and
separate. Therefore, cooks attempt to keep the temperature of the sauces just
slightly warm [110 to 120F (43.3 to 48.9C)] when these products are prepared.
In the attempt to maintain the stability of the sauces, these sauces are held
at temperatures of 110 to 115F (43.3 to 46.1C). These temperatures allow the
growth of pathogenic bacteria such as Salmonella spp.
Cooks must understand
the importance of acid and temperature in the preparation of egg-based sauces,
mayonnaise, and Caesar dressing in order to prepare these items safely. The
procedure is accomplished by diluting and acidifying the yolk of eggs and
heating the mixture to a pasteurizing temperature [heating for a sufficient
period of time necessary for a 100,000-to-1 CFU/g (5D) reduction]. This
procedure ensures the destruction of vegetative cells of Salmonella spp. and
other pathogenic bacteria such as L. monocytogenes and Escherichia coli
O157:H7. The method has been adapted from that described by McGee (1990a,
1990b). Actually many formulated cookbook recipes for mayonnaise, Caesar
dressing, Hollandaise and Béarnaise sauce include more than enough acid.
However, the amount of acid in these foods is not recognized as a critical
The first step is to recognize that if the egg yolk protein
is mixed with an equal volume of water and from one-third to an equal volume of
lemon juice or vinegar, the temperature at which coagulation of the egg yolk
protein occurs is raised. When the egg yolk/acid mixture is heated to 150F
(65.6C), vegetative pathogenic bacteria are reduced at least 100,000 to 1
CFU/g, while the egg yolk proteins have not been heated sufficiently to
denature and coagulate because of the water dilution and acid. It is critically
important that an accurate thermocouple thermometer (such as the Atkins 33040 )
be used to measure the temperature of the mixture. Temperature measurement is
necessary to ensure that the mixture is heated to 150F (65.6C) to assure
safety, but not heated to temperatures above this point [approximately 180 to
190F (82.2 to 87.8C)] which cause the yolk proteins to coagulate.
emulsifying capability of egg yolk is mainly related to its content of lecithin
(about 1.22% of the yolk) (Stadleman 1986). Lecithin is a phospholipid and is
not affected by the acid/heat pasteurization process and remains an effective
emulsifying agent in the pasteurized egg yolk/acid mixture.
Procedures for Cold Oil Sauces Mayonnaise and Caesar dressing are examples of
cold oil sauces containing egg yolks. See recipe formulations for mayonnaise
and Caesar dressing
Method for assuring destruction of Salmonella spp.
in egg yolk.
Place egg yolk(s) in a small, stainless steel bowl. (The
container must be large enough so that it can allow the egg yolk/acid mixture
to be stirred or whisked as it is heated.) Place the container containing the
egg yolk/acid mixture in a pan or bowl of water (such as a small double boiler)
that is at a simmering temperature of 180 to 190F (82.2 to 87.8C). Heat the
yolk/acid mixture to a temperature of 150F (65.6C). This will take about 1
minute. The mixture must be stirred or whisked constantly and the temperature
measured frequently by using a micro-tip thermocouple thermometer (such as the
Atkins 33040 ). Immediately remove the pan containing the yolk/acid mixture
from the hot-water heat source. The yolk/acid mixture is now pasteurized and
can be used in the preparation of mayonnaise and Caesar dressing.
for these products should be checked, or recipes provided in this paper should
be used to assure that there is the correct amount of acidity. As a starting
point, the standard of identity for vinegar is 5% acetic acid. The amount of
citric acid in lemon juice (bottled or freshly squeezed) is 4.7%. A typical
mayonnaise should be prepared with 1 raw egg yolk per 8 ounces of oil and the
acid concentration should be 1.4% of the aqueous phase as recommended by the
FDA (CFR Title 21 Part 101.100).