Note: Descriptions are shown in the official language in which they were submitted.
REDI~CTION OF_NI~ROSAMIN F_ MATION
IN PROCESSED MEAT PRODUCTS
. . . _ _ _ . _ _
TEC~NICAL FlFLD: -
This invcntion relates to the reduction of nitro-
samine formation in processed meat products particularly
in nitrite cured meats. More specifically, the invention
relates to the process for reduction of cured meats, such
as bacon, which are cooked at high temperatures by grill-
ing or frying in their preparation for eating.
BACKGRO~ND ART:
It is well known to treat fresh meats with a
curiny brine comprising an alkaline metal nitrite which
provides a preservative action to the meat. The nitrite
has the particular function of converting pigments, such
as myoglobin and hemoglobin, to their nitrosyl derivatives
to give the meat its characteristic color. The nitrite
is particularly active ayainst food spoiling microorgan-
isms of the species Clostridiwn and Salmonella. Organic
nitrites may be substituted for the alkaline metalnitrite.
It has been found that meats ~ed with conve~ition~
curir-g mixtures result in minute amounts of undesirable
nitrosamines to be formed on (ooking. That is, the cooXed
cured meat product contains either n-nitrosopyrrolidine (NNP)
or n--dimethyl nitrosamine (DNN), or both, which are known to
be carcinogenic materials. Thus, it is desirable to reduce,
eliminate or pre~ent the formation of these nitrosamines in
the cooked meat product. Bacon is such a cured meat product
with over seven hundred (700) meat producers supplying over
25,000,000 pounds of bacon per week in the United States.
Recent tests for determining the source of nitro-
samine in the cured meat products are not conclusive. At the
present time, it is not c]ear where or how the particular
nitrosamine is being formed. Complex conditions within the
meat product during processing have, to date, prevcnted the
specific determination of any precursors of the nitrosamine
in the meat product.
There have been several at-ternpts -to reduce or con-
-trol the nitrosamine forrnation in cured meats. These prior
art procedures are represented by the patents 4,039,690,
4,076,849, 4,079,153 and 4,088,793. These patents refer to
the use of various compounds such as aromatic primary and
secondary amines, and otller sophisticated compound usage
which would take years to put into practical use because of
~overnmental safety standards associated with chemicals in
food products~ Thus, -~here is a critical need to find a
method for reducing and controlling nitrosamines that will
not take years to deve]op and use comrnercially.
The inoculation of foods with bacteria from the
41~
families of I..actobacteriaceae and Micrococcaceae is well
known to produce flavor in cured meats (U.S. Patent
3,193S391). It is also well known to use lacti,c acid pro-
ducing bacteria in other meat curing processes (U.S. Patents
5 3,794,739, 3,814,817 and 4,013,797). It is also well kno~n
to use lactic acid as an accelerating agent in a curing
brine solution ~U.S. Patent 2,681,287). Surprisingly, it
has been found -that certain well known food additives may be
~Ised under specific conditions to produce the desired re-
sults.
DISCLOSURE OF INVENTION:
_ _ . _ _ _ _ _ _ _ . _ _ _ _ _ _
'I`he primary object of the invention is to modify
existing meat processing procedures in a rnanner to obtain
governmental approval quickly to meet the critical need
stated above.
Another object of the i,nvention is to provide a
curing solution for meats incorporating known food additives
in amounts sufficient to produce the new and unexpected re-
sult of reducing nitrosamine formation in the cured meatproduct.
A further object of the invention is to provide a
process of treating foods in a manner to provide a nitrite
cured meat product wherein the formation of nitrosarnine dur-
iny cookiny has }~een substantially eliminated.
The present i.nvention is d;,l-ected to a pl-ocess
for n;trosamine control in nitrite cured meats and specific
compositions to effect the process. An efective a~ount of
starter culture and/or chemical acidulant is added to a
typical nitrite pickle or curing solution for treating meats
to reduce the quantity of nitrosamine formed when the cured
meat is cooked at frying temperatures. The starter culture
is capable of producing an organic acid from fermentable
carbohydrate. In a specific embodiment of the invention,
bacon is cured with a nitrite curing solution containing an
amount of lactic acid starter culture and/or chemical acidu-
lant in an amount effective to reduce the quantity of nitro-
samine formed during cookin~ of the nitrite cured bacon.
According to well known chemical reactions, nitro-
samines form in an acidic environment. Where the additives
to the nitrite curing solution in the present invention are
used, there is generally a reduction in the pH values, thus
producing a more acidic environment. However, it has been
discovered that even ullder such conditiolls, the formation of
nitrosamine in the subsequently cooked meat product is sub-
stantially reduced.
DETAILED DE.SCRII'rlON:
Bacon is a typical meat produc-t subjected to
nitrite curing. Bacon is normally pLocessed by pumping raw
pork bellies with a curing pickle. A typical pickle compo-
sition is as fol]ows:
tj
Salt 17 0
Sugar (sucrose) 3.6
Sodium tripolyphospllate 2.6
Sodium nitrite 0.17
Sodium erythorbate 0.6
Water 76 0
100.0
The pork bellies are yenerally pumped to obtain
10~ additional weight before being smoked. That is, 100
pounds of raw bellies would weigh 110 pounds after the pump-
ing operation. The bellies are then hung in the smokehouse
where they are heat processed at a temperature in the range
of 125 to 135~ for a period of from about six to twelve
ihours to obtain an internal temperature in the bellies of
from about 126 to 128F. The cured bellies are then chiUea,
sliced and vacuum packaged.
The product must shrink to its original green
weight during the heat processing step. That is, the 110
pounds of weight would be reduced back to 100 pounds. The
sliced bacon generally contains sufficiently high levels of
residual nitrite of from about 20 to ]00 parts per million
which subsequently combines with secondary amines to form
nitrosamines during frying of the bacon. The pH of the
bacon subjected to standard processing procedures as ais-
cussed hereinabove is generally about 6.0 to 6.4.
Several specimens of bacon were prepared frompork bellies which have been treated in accordance with the
following several examples.
~XAMPLE I
Cont,rol Bacon Specimen
A pork bell.y was pumped to 10~ by weight with the
above noted typical nitrite curing composition. The pumped
belly was then processed normally at 135F. in a smokehouse
with natural smoke to an internal temperature of about 126
to 128F. This smokehouse treatment was for a period of
about 7.5 hours. The smoked belly was then frozen, sliced
and analyzed for residual nitrite and pH levels before frying
and for the quantity of nitrosarnines after frying. The
analytical result of these tests was as follows:
Before frying-
residual nitrite 60 ppm
pH 6.4
After frying:
n--dimethyl nitrosamine 2.2 ppb
l-nitro.sopyrrolidine27 ppb
Residual nitrites generally fall within a range
of 40 to 60 using conventional curing compositions. The
acceptable level, of nitrosamines after frying is set by the
~nited States Government at 10 parts per billion or less and
preferably 5 parts per billion or less. N-dimethyl nitro-
samine is generally found in meat products, such as sausage
and frankfurters. The l--nilrosopyrrolidine is prevalent in
bacon.
The following examples II through V involve the
use of different pi.ckle curing solutions which have been
used to pump pork bellies 10~ by weight as i,n the control
Example I. The prvcessing following the p~ping procedure
is also the same as the control Example I, wherein the
pumped pork belly ~as smoked at 135DF. with natural smoke
to an internal temperature of about 126 to 128F. The
smoking step was extended for approximately 7.5 hours. The
smoked belly was then subsequently frozen, sliced and ana-
lyzed for residual nitrite and pH level before ~rying and
for the quantity of nitrosamines after frying the sliced
specimen. Each of the e~amples set forth the analytical
results as stated before and after ~rying.
~ EXAMPLE II
. __
Pickle Curing Composition
Salt 17.0
Sugar (sucrose) 3.6
Sodium tr:ipolyphosphate 2.6
Sodium nilrite 0.17
Sodium erythorbate 0.6
~ater 76.02
Lactic acid starter culture
(ABC-18)* 0.01
100.O
Anal~tical Results
Before frying:
residual nitrite 8.Q ppm
pH 5.8
After frying:
n-dimethyl nitrosamine 1.1 ppb
l-nitrosopyrrolidine 15.0 ppb
* Trade Mark
EXAMPLE III
Pickle Curing Composition
Salt 17.0
Sugar (sucrose) 10.0
Sodium nitrite 0.17
Sodium erythorbate 0.6
Water 72.22
Lactic acid star-ter culture
(ABC-18) 0 01
l O O . O
Analytical Results
Before frying:
residual nitrite 20.0 ppm
pH 5.8
After frying:
n-dimethyl nitrosamine 1.3 ppb
l-nitrosopyrrolidine10.0 ppb
EXAMPLE IV
Pickle Curing Composition
~
Salt 17.0
Dextrose (corn sugar)10.0
Sodium nitrite 0.17
Sodium erythorbate 0.6
Water 72 22
Lactic acid starter culture
(ABC-18j 0.01
100. 0
Analytical Results
__ _ __
Before frying: -
residual nitrite 11.0 ppm
pH 5.8
After frying:
n-dimethyl nitrosamine 0.6 ppD
l-nitrosopyrrolidine 1.1 ppb
EX~MP E V
Pickle Curing Compositlon
Salt 17.0 %
Sugar ~sucrose~ 3.6
- Sod:ium tripolyphosphate 2.6
Sodium nitrite 0.17
Sodium erythorbate 0.6
Water 75 03
Lact-ide 1.0
100. 0
Analytical Re~u~ts
Before frying:
residual nitrite 9.0 ppm
pH 5.8
After frying:
n-dimethyl nitrosamin~ 0.9 ppb
l-nitrosopyrrolidine 15.0 ppb
16
- 10 -
The lactic acid starter culture is commercially
available from the American ~acterological & Chemical
Research Corporation and is designated as "Strain 18."
More specifically, Strain 18 is Lactobacillus plantarum
of the family of Lactobacteriaceae. With respect to
Example V, the lactide is a chemical acidulant which, in
addition to glucono-delta-lactone, lactic acid, acetic
acid and the like, will operate to reduce the amount of
nitrosamine formation in cured meat products upon cooking
of same.
The specific culture used in the examples was
a frozen concentrate of a living bacteria. ~owever, this
bacteria may also be in dried fol~. A dead bacteria might
also be used where there are active metabolic enzymes
still present therein.
The following Examples VI and VII are di.rected
to the use of pickle curing compositions as were used in
Examples II and IV, respectively. I~owever, the processing
parameters in these particular Examples VI and VII include
an initial heat processing step at a temperature of from
%5 to 100F. for an extended period of time, from about
12 to 18 hours. ~ore specifically, each of the pumped
bellies in the Examples VI and VII have been held at 100 F.
for a period of about 16 hours~ The pretreated pumped
bellies are then subjected to the same smokehouse treat-
ment as was effected for the contro] bacon specimen of
Example I.
11~4~16
EXAMPLE VI
Pickle .Curing Composition
Sal~ 17.0 %
- Sugar (sucrose) 3.6
. 5 Sodium tripolyphosphate 2.6
Sodium nitrite 0.17
Sodium erythorbate 0.6
~ater 76.02
Lactic acid starter culture
(ABC-18) 0.01
100. 0
Analytical Results
- -
Before frying:
residual nitrite 8.0 ppm
pH 6.0
After frying:
n-dimethyl nitrosamine 1.0 ppb
l-nitrosopyrrolidine 13.0 ppb
EXAMPLE VII
Pickle Curing Composition
Salt 17.0 %
Dextrose (corn sugar) 10.0
Sodium nitrite 0.17
Sodium erythorbate 0.6
Water 72.22
Lactic acid starter culture
- (ABC-18) 0.01
100. 0
- 12 -
Analytical Results
Be~ore frying:
residual nitrite 5.0 ppm
p~ 5.6
- 5 After frying:
n-dimethyl nitrosamine 0.7 ppb
l-nitrosopyrrolidine 4 0 ppb
The raw pork bellies pumped with pickle curing solutions
Or the above Examples contained large numbers of lactic
acid microorganisms in an amount of from about 105 to 107
microorganisms. The microorganisms produce lactic acid to
lower the p~ of the environment. Once the pH reaches a
level of from about 4.8 to 5.2 pH, the microorganisms are
killed. That is, the production of -the lactic acid ulti-
mately produces a bacteriacide environment. Unlike mater-
ial fermentation, where there are a variety of microorgan-
isms, the use of a single species of a microorganism
provides the opportunity to control the requisite pH
levels more effectively~
The tripolyphosphate acts as a buffering agent
in a well known manner within the pickling compositions
of the above Examples. The erthyorbate is a coloring
additive or agent which provides co]or stability to the
meat product.
The starting pork bellies and the analytical
methods used to determine the nitrosamine levels are
known to be variable. However, the E~amples clearly show
4 i~
the extremely significant reduction and control of nitro-
.samine formation in nitrite cured meat products according
to the present invention. The particular levels to which
the nitrosamines have been reduced are well below the
S acceptable levels established by the U.S. Government.
The particular mechanism by which the nitrosamine is re-
duced or controlled is not-known. As already noted, the
reaction environment within the meat product being cured
is ex.tremely complex. Thus, no a-ttempt beyond a -theoreti-
cal assumption is made to explain the surprising new andunexpected results obtained through the use of the nitrite
pickling compositions of the present invention.
