CROSS REFERENCE TO RELATED APPLICATIONS
This application is a continuation-in-part of a continuation-in-part
of i.a. Serial No. 07/416,963 filed October 4, 1989 which matured into U.S. Patent
NO. 5,039,537, issued 08/31/91; and Serial NO. 07/358,650 filed May 26, 1989, which
matured into U.S: Patent NO. 4,994,297 issued 2/19/91.
FIELD OF THE INVENTION
This invention relates to a process for producing liquid products
and their use coloring and flavoring foodstuffs. More particularly, this invention
is concerned with pyrolyzing sugars and starches to produce a liquid product for
coloring and flavoring foodstuffs.
BACKGROUND OF THE INVENTION
Pyrolysis reactions produce a complex and variable mixture of chemicals
and include vaporous compounds which are normally liquid at room temperature.
Pyrolysis is a general term for the thermal decomposition of any organic material
(i.e. wood, plants, fossil fuels etc.) and can occur during a combustion process
or in the absence of combustion. In the former, the oxidation or burning of a portion
of the organic material provides the head required to vaporize and decompose the
remainder. In the absence of combustion, heat must be supplied indirectly from
some other source (i.e. radiation, a solid or gaseous heat carrier, or conduction
through reactor walls, etc.).
Pyrolysis of organic material or biomass produces liquids (condensable
vapors), gases (non-condensables vapors) and solids (char and ash) in varying
proportions depending upon reaction conditions. The pyrolysis liquids can be further
subdivided into water-soluble condensable vapors and water insoluble components.
It is known that the desirable active ingredients for smoke flavoring are among
the water-soluble condensable vapors (liquids).
Use of pyrolysis liquid solutions as a replacement for smoking foodstuffs
by direct contact with smoke produced from burning wood has become a standard
industry practice. When applied to the surface of meats and other proteinaceous
foodstuffs, common pyrolysis solutions not only give the foodstuff a characteristic
smoke flavor, but react with the proteins to produce a coloring typical of smoked
One such commercial liquid smoke preparation is the aqueous liquid
smoke flavoring described by Hollenbeck in U.S. Patent No. 3,106,473. This flavoring
product is produced by slow pyrolysis or partial combustion of wood with limited
access to air, followed by subsequent solvation of the desirable smoke constituents
into water. The water-soluble condensable vapors are used for smoke flavor, while
a water-insoluble phase which contains tar, polymers, polycyclic aromatic hydrocarbons
including benzo(a)pyrene, waxes and other undesirable products unsuitable for use
in food applications is discarded.
Another method of producing liquid solutions for smoke flavoring
foods is the fast pyrolysis of wood or cellulose process which is disclosed by
Underwood et al. in U.S. Patent No. 4,876,108. The liquids produced by the fast
pyrolysis process are collected and diluted with water to achieve a partial phase
separation and to provide an aqueous liquid smoke flavored solution.
WO 90/12514 relates to a process to make liquid smoke compositions
from wood smoke which is refined to preferentially remove selected undesireable
smoke components. The process essentially includes the contacting of an aqueous
liquid smoke solution having a soluble organics concentration of about 4 to 40°
Brix with both polymeric nonionic and ionic resins to give a composition having
a reduced phenol and basic constituent content. The improved flavor of the product
thus obtained is due to removal of particular compounds which are derived from
the pyrolysis of wood.
O. Fennema, "Food Chemistry", 2nd edition, publ. 1985, by Marcel Dekker,
Inc. (New York), p. 98 discloses that directly heating carbohydrates, particularly
sugars and sugar syrups, produces a complex group of reactions termed "caramelization".
It is mentioned therein that three types of caramel colors are commercially produced
Regardless of whether wood or cellulose is pyrolyzed by a slow pyrolysis
method or by a fast pyrolysis method the resulting smoke flavored liquid solutions
may have a stronger smoke flavoring for some foodstuffs for a given degree of smoke
coloring than is desirable for the tastes of some consumers. Even though some
consumers prefer a very mild to little smoke flavor, there is still a preference
that the flavored foodstuff, especially meat, have the typical full brown color
associated with well smoked foodstuffs. Even though a need for such a smoke flavored
liquid solution exists none seems to be presently available.
SUMMARY OF THE INVENTION
The present invention provides a high browning, aqueous composition
or liquid product that has been derived from a sugar or a starch in which the
composition or product has a soluble organic content of less than about 50° Brix,
a browning index greater than about 30 and a ratio of titratable acidity to browning
index of less than about 0.06. A preferred composition or product has a browning
index greater than 50 and more preferably greater than 75. A preferred high browning
aqueous composition of this invention is a liquid product derived from pyrolyzed
corn syrup having a soluble organic content of about 45° Brix, a browning index
of about 104 and a titratable acidity of about 3.2%. The reduced acidity and high
browning index provide a liquid product which may be particularly beneficial to
color encased foodstuffs such as sausages or other meat products which are prepared
by known casing processes.
The present invention also provides a process for producing a high
browning liquid product which includes the steps of pyrolyzing a feedstock which
is a member of the group consisting of sugar, starch and mixtures thereof to produce
a vaporous pyrolysis product; condensing the vaporous pyrolysis product to produce
a water-soluble pyrolysis liquid contacting the water-soluble pyrolysis liquid
with an organic solvent which is essentially insoluble in water to extract flavoring
materials from the water soluble pyrolysis liquid into the organic solvent; and
separating the extracted liquid from the organic solvent to yield a browning liquid
product which has substantially no detectable flavoring ability by taste.
It is generally advantageous to add sufficient water to dilute the
water-soluble pyrolysis liquid phase to reduce its Brix value to about 30° Brix
or lower in order to ensure the complete separation of the desired water-soluble
components from the undesired water-insoluble components. Specifically, if the
Brix value of the water-soluble pyrolysis liquid phase is greater than about 30°
Brix, the separation of benzo(a)pyrene from the aqueous layer may be incomplete.
Furthermore, it is also desirable to ensure that the water-soluble
liquid phase be less than about 42° Brix when further extracting or treating the
water-soluble liquid phase. At Brix values greater than about 42° Brix, subsequent
extraction or treatment steps are less effective primarily due to the greater solvating
effects of the organic components of the more concentrated solutions.
The resulting water-soluble pyrolysis liquid phase provides a product
which is capable of imparting a very full brown color when a sufficient amount
is applied to foodstuffs, such as meat and specifically bacon, followed by heating
to complete processing of the treated foodstuffs. Furthermore, treatment of a
foodstuff with the product leads to a brown colored foodstuff which has little
or substantially no smoke flavor or aroma.
The initial water-soluble liquid pyrolysis product described above,
and desirable having a maximum Brix value of about 30°, according to the invention
is further improved by additional treatments to further lower the amounts of flavoring
materials in the product. The product is extracted with a suitable water-insoluble
organic solvent, such as methylene chloride, to remove flavoring materials, especially
food flavoring materials which provide smoke flavor and aroma, while retaining
those materials which provide browning activity; preferably, hydroxyacetaldehyde
which is water-soluble, but quite insoluble or has very little solubility in organic
solvents, such as methylene chloride. Generally, suitable extraction solvents include
those with a proper range of hydrogen bonding parameters and an appropriate polarity
index to solubilize the undesired flavor-supplying organic materials present in
the water-soluble product. One suitable alternative solvent is chloroform. After
extraction, the organic solvent is then separated from the aqueous phase to yield
a food browning liquid product which has little or substantially no flavoring ability.
The water-soluble pyrolysis liquid, with or without a prior extraction
with methylene chloride or some other suitable organic solvent, may also be treated
with a nonionic resin, cationic resin or a combination of such resins, to also
remove undesired contaminants and flavoring materials. The resin treatment of liquid
solutions produced by slow pyrolysis of wood is described in U.S. Patent No. 4,959,232.
The conditions disclosed therein are suitable for further processing
the water-soluble pyrolysis liquid obtained from a sugar, starch or mixtures thereof,
with or without a prior organic solvent extraction. The resulting food browning
liquid product has little or substantially no flavoring ability.
After suitable treatment the browning liquid product can be diluted
with water or concentrated for appropriate food browning ability depending on the
type of application process which is to be used as well as the type of foodstuff
which is to be treated.
DETAILED DESCRIPTION OF THE INVENTION
The present invention provides a method for producing useful flavoring
and browning products by pyrolyzing sugars and starches.
Some of the sugars which may be suitably pyrolyzed according to the
invention are mono-, di- and trisaccharides. Specific sugars and sugary products
which can be pyrolyzed are glucose, sucrose, dextrose, invert sugar, galactose,
lactose, corn syrup, malt syrups and molasses. Specifically, cow's milk is a well
known source of lactose and lactose found in whey is a relatively abundant by-product
of the cheese making process. Thus, lactose is a unique readily available sugar
that is not derived from plant sources. Due to availability and cost, dextrose,
lactose and corn syrups are presently preferred sugars for use in the invention.
Starches which may be pyrolyzed include corn starch, potato starch,
wheat starch, oat starch, tapioca starch and rice starch.
The sugar or starch may be pyrolyzed by slow pyrolysis although fast
pyrolysis is preferred.
Slow pyrolysis is characterized by relatively slow thermal reactions
occurring at moderate temperatures. A typical slow pyrolysis reactor temperature
is approximately 420°C. Depending on the method of heating, the temperature gradient
in a slow pyrolysis reactor may be from 600°C at the heat transfer surface to
250°C at the feedstock surface. Residence times of the solids in the slow pyrolysis
reactor may be about one to ten minutes.
The fast pyrolysis process is designed to achieve a very high temperature
within a minimum amount of time as well as having a relatively short reactor residence
time at the sugar or starch pyrolysis temperature. Short residence times at high
temperatures can be achieved in several ways. However, the parameters to be optimized
in any fast pyrolysis of a sugar or starch to produce a suitable liquid product
in high liquid yields include:
- 1) High heating rates of the sugar or starch feedstock (greater than 1,000°C
- 2) Vapor residence times (i.e. the average time that the gas/vapor phase remains
in the reactor) greater than about 0.05 sec. and less than about 1.0 sec. and
preferably less than 0.6 sec.;
- 3) Isothermal reaction temperatures between about 400 and 800°C; and
- 4) Quenching of the liquid/vapor product to temperatures of less than 300°C
in less than 0.6 sec..
A first fast pyrolysis method, or vacuum pyrolysis method, is based
on the principle that primary pyrolysis products can be withdrawn from the reactor
under vacuum conditions before they have a chance to react further and produce
secondary pyrolysis products. This vacuum pyrolysis method has been described
by Roy et al., in "Pyrolysis Under Vacuum of Aspen Poplar," Fundamentals of
Thermo-Chemical Biomass Conversion, R.P. Overend et al. (editors) Elsevier
(publisher) (1985) the contents of which is incorporated herein by reference.
In this process, the solid sugar or starch feedstock remains in the reactor until
completely reacted and the heating rate of the sugar or starch is much slower
than a rapid thermal process or a fluidized bed pyrolysis process, both subsequently
described herein. Reactions of primary pyrolysis products to produce secondary
pyrolysis products, however, are reduced by quickly removing and cooling the primary
pyrolysis vapors. As such, the heating rate is less significant when secondary
reactions are limited.
A second fast pyrolysis method, often referred to as "flash" pyrolysis,
uses a fluidized bed reactor system operating at a high temperature, generally
between 400 and 650°C. Reactor residence times of about 0.5 to about 3 seconds
are particularly suitable. (See, e.g., Scott et al., "Production of Liquids from
Biomass by Continuous Fast Pyrolysis," Bioenergy 84 vol. 3, Biomass Conversion,
(1984), the contents of which are incorporated herein by reference).
A third fast pyrolysis method, referred to as rapid thermal processing,
is a fast pyrolysis method which uses hot particulate solids and/or inert gases
to rapidly transfer heat to a feedstock in a reactor system.
These fast pyrolysis methods offer much improved yields and improved
quality of liquid products compared to slow, low temperature pyrolysis systems.
The pyrolysis process may be effected using a variety of sugar or
starch feedstocks. Pyrolysis of a solid sugar or starch as well as pyrolysis of
solutions, syrups or suspensions of a sugar or starch in a solvent or liquid carrier
may all be used. Preferably, the type of feedstock will be selected to allow the
use of feed systems or injectors which are compatible with specific pyrolysis
apparatus and equipment. Further, it is not necessary for the feedstock to be homogenous.
Mixtures of impure sugar or starch compositions may all be used as pyrolysis feedstocks
provided the additional components or impurities do not interfere with either
pyrolysis of the feedstock or isolation of the liquid product or cause problems
with the pyrolysis apparatus. Specifically, low nitrogen content whey solutions
containing lactose, as well as other by-products of the cheese making process,
may be pyrolyzed.
A wide variety of sugars can be thermally degraded to form a pyrolysis
liquid containing the food browning agent hydroxyacetaldehyde (HAA). For example,
each of the sugars listed in Table 1 was added to water to make a 5 wt./vol.%
sugar solution. Each solution was then injected into a Varian gas chromatograph
with an injection port temperature of 250°C to give pyrolyzed products, including
hydroxyacetaldehyde. The amounts of hydroxyacetaldehyde produced from the listed
sugars are set forth in Table 1.
NUMBER OF CARBON ATOMS
PARTS PER MILLION OF HAA FORMED
While varying amounts of hydroxyacetaldehyde were produced from each
of the above-identified sugars, the results listed in Table 1 demonstrate that
the observed yield is related to the thermal lability of the sugar. Due to the
250°C injector port temperature limit in this experiment, only lyxose approached
the theoretical maximum yield of two divided by the number of carbons atoms per
monosaccharide unit, the lyxose yield being 38%. It can be concluded that nearly
all simple sugars can be pyrolyzed to yield varying amounts of hydroxyacetaldehyde
at about 250°C.
Both aldoses and ketoses (fructose and sorbose are ketoses, the remaining
sugars are aldoses) will pyrolyze to yield hydroxyacetaldehyde. Galactose and
mannose are more thermally resistant to pyrolysis to hydroxyacetaldehyde than the
other sugars. Neither could be pyrolyzed under the conditions of this experiment
at 250°C. Furthermore, additional thermal stability results from the combination
of two or more simple sugars in a pyrolyzed molecule as is seen in data for cellobiose,
lactose, maltose and sucrose.
Based on the data for glucose and galactose when pyrolyzed independently,
it was expected that, on a molar basis, the yield of hydroxyacetaldehyde, a known
food browning agent, from lactose would be about half that of glucose. Surprisingly,
hydroxyacetaldehyde is formed from the galactose portion of lactose as well as
from the glucose portion. Either the epimeric alpha- or beta-form of lactose is
suitable as the yield is independent of the type of disaccharide linkage.
While not meant to be a limitation of the mechanism of carbohydrate
pyrolysis, it appears than there exists a kinetic bias to cleave lactose between
carbons 2 and 3 to yield the two carbon hydroxyacetaldehyde. A mechanism which
suggests this bias is reported by Piskorz et al., J. Anal. Appl. Pyrol.,
9:121-137 (1986). The observed yield of the pyrolysis products is believed to
be a matter of having sufficiently rapid heat transfer for the kinetics of pyrolysis
to favor this pathway as opposed to dehydration by other alternate pathways. Short
vapor residence times are believed to limit undesired secondary reactions. Furthermore,
no oxygen should be present.
The desired liquid products of this invention may be directly applied
to a foodstuff using techniques and methods well known in the liquid smoke art.
Application techniques such as dipping, spraying, pumping and soaking are all
suitable methods for browning a foodstuff with these present liquids.
The liquid product of this invention provides the capability of browning
a foodstuff with a minimum concentration of hydroxyacetaldehyde in the liquid
product. Suitable concentrations of hydroxyacetaldehyde in a liquid solution required
to impart a rich golden brown color to meat when the meat is cooked in a microwave
oven are listed in Table 2. To impart color, the solution is applied to the surface
of Swift Premium Brown and Serve Sausages by a 2 to 3 second dip. The sausages
are then microwaved for one minute along with untreated sausages which serve as
controls. After microwaving the sausages are evaluated for visual color appeal.
Thus, liquid products having a hydroxyacetaldehyde concentration as low as 0.05%
may be used to impart a noticeable golden brown color to sausages.
HAA = hydroxyacetaldehyde
HAA in Solution (Wt./vol.%)
Surface Coating Concentration (µg HAA/cm2)
Total Product Loading (µg HAA/g product)
Light Golden Brown
Very Light Brown
In addition to direct application to a foodstuff, the liquid product
of this invention may also be applied to foodstuffs indirectly by applying the
liquids to sausage and food product casings. The application to casings indirectly
allows a processor to impart a brown color to a particular food product.
Any well known method may be used to contact the sausage or foodstuff
casing with the liquid product. See, for example, the methods disclosed in U.S.
Patents 3,330,669 and 4,504,500. Suitable methods for contacting foodstuff casings
with the liquid product are also described in U.S. patent application Serial No.
07/416,963 filed October 4, 1989 which matured into U.S. Patent No. 5,039,537
Food casings suitable for use in the present invention include tubular
casings, and preferably tubular cellulosic casings, that are prepared by any of
the methods well known in the art. Such casings are generally non-fibrous, flexible,
thin-walled seamless casings formed of regenerated cellulose or cellulose ethers,
such as hydroxyethyl cellulose, in a variety of diameters. Also suitable are tubular
cellulosic casings having a fibrous reinforcing web embedded in the wall of the
casings, commonly called fibrous food casings.
The liquid product may be applied to the outer surface of the food
casing by passing the casing through a bath of the browning liquid product. The
liquid product is generally allowed to soak into the casing before doctoring off
any excess liquid by passing the casing through squeeze rolls or wipers for an
amount of time sufficient for the casing to incorporate the desired amount of
product into the casing. The liquid product may also be externally applied to the
casing by methods other than dipping, such as spraying, brushing or roll-coating.
Another method of treating the casing with the liquid product of
this invention involves passing a flattened, tubular, cellulose sausage casing
over guide rolls through a dip tank which contains the liquid product. The casing
passes over additional guide rolls after exiting the dip tank, and then passes
between squeeze rolls which minimize any excess carryover of the liquid smoke
composition. The total contact time of the casing with the liquid smoke composition
in the dip tank, and with excess liquid smoke composition on the casing passing
over the guide rolls before the casing passes through the squeeze rolls, typically
determines the amount of smoke coloring and flavoring of the liquid smoke composition
that the casing will incorporate. The casing is then sent on to conventional further
processing, including conventional humidification, as may be required, and conventional
Alternatively, the liquid product may be applied to the internal
surface of the casing by any of several well-known procedures. These include slugging
or bubble coating, spraying, and coating while shirring. The slugging method for
coating the inside of a casing involves filling a portion of the casing with the
coating material, so that the slug or coating material generally resides at the
bottom of a "U" shape formed by the casing, and then moving the continuous indefinite
length of casing so that the slug of coating material remains confined within the
casing, while the casing moves past the slug and is coated on its inside wall
by the coating material contained within the slug.
The casing may then be shirred by conventional methods or, prior
to shirring, it may be dried or humidified before shirring to a water content suitable
for shirring or further processing. The need for conventional drying or humidification
after the external liquid treatment depends on the water content of the casing
after treatment and the type of casing. If the casing is a non-fibrous casing,
a water content within the range of about 8-18 wt.% water immediately before shirring
is typical, and for fibrous casing a water content within the range of about 11-35
wt.% water immediately before shirring is typical, where weight percent is based
on the total weight of casing including water.
The hydroxyacetaldehyde present in the browning liquid product is
also a particularly preferred agent when used with collagen casings because the
difunctional hydroxyacetaldehyde is an effective cross-linking agent. Thus, the
physical properties of the collagen casings may be improved by the cross-linking
provided by hydroxyacetaldehyde.
In the indirect application of the liquid product to sausage or food
casings, the lack of a strong or an undesirable flavor is a notable, additional
advantage. Conventional liquid smoke products generally must be used at high concentrations
to impart enough color or browning to the encased foodstuff. These high concentrations,
however, typically have a flavor which is sometimes more intense than desired.
The use of the liquid products provided hereby on foodstuff casings allows a processor
to achieve the desired brown color without necessarily imparting smoke flavor
characteristics to the foods.
BRIEF DESCRIPTION OF THE DRAWINGS
Details of embodiments of the invention are described by reference
to the accompanying drawings in which:
DETAILED DESCRIPTION OF THE DRAWINGS
- Fig. 1 is a schematic representation of an apparatus useful in a fast pyrolysis
method referred to as rapid thermal processing.
- Fig. 2 is a top plan view of the reactor of the pyrolysis apparatus of Fig.
- Fig. 3 is a sectional view taken on the line III-III of Fig. 2.
- Fig. 4 is a schematic representation of a fast pyrolysis apparatus including
an upflow reactor.
In the following description the corresponding elements as shown
in each figure of the drawings are given the same reference number.
While Figs. 1 to 3 of the accompanying drawings and the description
thereof pertain to Rapid Thermal Processing, similar products can be produced
using other fast pyrolysis apparatus and processes, including vacuum pyrolysis
and flash pyrolysis as well as other systems that result in a high temperature
with a limited residence time.
The major components of the apparatus used in the rapid thermal process
are illustrated in Fig. 1. Rapid mixing and heat transfer are carried out in two
vessels. The first vessel or thermal mixer (1) allows heat to be transferred to
the sugar or starch feedstock from hot inert particulate solids, an inert gas which
can be gaseous nitrogen, or a combination of the two. The second vessel or quencher
(2) allows fast quenching of the reaction products to prevent the initial pyrolysis
products from undergoing secondary reactions.
As shown in Figures 2 and 3 the thermal mixer (1) has opposing converging
inlets (3) for the heated inert particulates. This system effectively destroys
the radial momentum of the particulate heat carrier causing severe turbulence.
The particulate feedstock is then injected from the top of the thermal mixer (1)
through a cooled tube (4) into the turbulent region where mixing occurs within
After heating and mixing occur, the feedstock and the primary pyrolysis
vapors are maintained at the reaction temperature for between 0.03 and 2 seconds.
The primary pyrolysis vapors are produced as soon as the feedstock is sufficiently
heated to start the pyrolysis reactions. The hot gaseous product is rapidly cooled
(i.e. less than 30 milliseconds) by the injection of a single tangential stream
of cryogenic nitrogen (5).
Mechanical table feeders may be used to supply the feedstock to the
reactor system. The solids pass from sealed hoppers (6) through a double funnel
system and are thereby metered onto a rotating table. Two fixed armatures sit
near the surface of the rotating table and plough the solids off the outer circumference.
The solids then fall from the table into a conical chamber where they are picked
up and carried into the transport line by nitrogen gas. The feed rate of the sugar
or starch particulate solids is controlled by setting the gap between the lower
funnel and the table. Fine control is exercised by the rotation speed of the table.
When inert particulate solids are required to supply the process
heat, the feeders (7) send the hot inert particulate solids through a non-mechanical
high temperature valve which operates at the reaction temperature. These hot inert
particulate solids are then sent on to the thermal mixer (1).
The solid particulate feedstock (or atomized sugar or starch liquid)
is then injected into the thermal mixer (1) through a water or air cooled tube
(4) into the turbulent region where effective mixing and rapid heating to at least
400°C occurs within 0.10 second, and preferably within 0.03 second.
Fast pyrolysis of the sugar or starch feedstock (1) continues in
a transport reactor (9). The transport reactor is a length of pipe which is indirectly
heated using an electrical oven (10) or directly heated by the combustion of natural
gas or propane. The mixture of hot gases and feedstock passes from the thermal
mixer (1), through the transport reactor (9), to the quencher (2) and to the solids
separator (23). With variation of the reactor volume and by manipulating the inert
heat carrier/feedstock flow rates, the residence time can be varied between 30
ms and 3 seconds. Reactor temperatures can be set in the range of 400 to 1000°C.
Preferable reactor temperatures are between 400 to 800°C and more preferably between
500 to 600°C. The heating rate that can be achieved with this apparatus is over
10,000°C per second.
An efficient cyclonic condensor (25) may be used to increase the
yield of recovered liquid products. In addition, an electrostatic precipitator
(24) can be integrated into a downstream gas line to recover additional liquid
After collection of the liquid products, water is added to cause
phase separation to reduce benzo(a)pyrene and tars concentration in the liquid
product. The amount of water added beyond that necessary to achieve effective
phase separation is to some extent a matter of choice. However, it is generally
desirable to dilute the raw liquid product with enough water to produce a water-soluble
liquid product having a maximum specific gravity of about 30° Brix.
Figure 4 illustrates another apparatus useful for the fast pyrolysis
of sugars and starches by the rapid thermal process. Bin (40) stores a supply of
the feedstock solid sugar or starch in granular or powder form. The feedstock
is removed from the bin (40) by an auger (42) and fed to the lower interior portion
of the reactor (44) above a windbox (101) and a grid plate (43). The auger (42)
may be water cooled at the inlet to the reactor to prevent premature pyrolysis,
which can produce tarry materials. Alternatively, a solution or syrup of a carbohydrate-containing
liquid feedstock may be injected into the reactor using a suitable well known
injector apparatus. Heated storage tank (110) stores a supply of a liquid feedstock.
The liquid feedstock is pumped from the storage tank (110) by a pump (112) through
a clean jacketed conduit (114). The liquid feedstock enters the reactor (44) through
an injector nozzle (116). The injector nozzle (116) may be cooled at the inlet
in the reactor by a water-cooled jacket (118) to prevent premature pyrolysis of
the liquid feedstock in the injector nozzle.
A stream of recirculation gas transport fluid is fed by a conduit
(100) into the windbox (101), through the grid plate (43) and into the lower portion
of the reactor (44) containing a heat transfer medium such as sand (45). Rapid
mixing and conductive heat transfer from the sand (45) to the sugar or starch
feedstock occurs in the reactor (44). Pyrolytic conversion of the feedstock to
a raw product vapor is initiated and continues through the reactor with upward
flow into the primary cyclone separator (48). The pyrolysis stream comprising
sand (45) and pyrolysis vapor is removed from the reactor (44) by conduit (46)
and fed to primary cyclone separator (48). The hot sand (45) is removed from the
product vapor stream in the separator (48) and recycled by means of a conduit (50)
to the reactor (44). The recycled sand (45) is reintroduced into the lower portion
of the reactor (44) at a point above the grid plate (43). Product vapor containing
char is withdrawn from the primary cyclone separator (48) by a conduit (52) and
fed to a secondary cyclone separator (54) which can be a high efficiency reverse
flow cyclone separator. Char and solid sand fines are removed in the secondary
cyclone and fed therefrom to a char catchpot (56) for disposal or further handling
The hot product stream is withdrawn from the top of the secondary
separator (54) through a conduit (58) which feeds the vapor comprising condensable
and noncondensable components and some fine residual char and ash to the lower
interior space of a baffled condenser (60) where the vapor is immediately quenched.
The condenser (60) uses the product liquid as the quench medium.
The condensed liquid product is withdrawn from the bottom of the
condenser (60) through a conduit (62) and is fed to a pump (64) which pumps it
to a heat exchanger (66) indirectly cooled by water. The cooled product liquid
is removed from the heat exchanger (66) and returned by conduit (68) to the top
of the condenser (60) as a spray. A conventional transparent vertical sight indicator
(61) is mounted on the lower part of the first condenser (60). The sight indicator
has high and low liquid level marks. When the volume of liquid in the condenser
(60) reaches the high level mark raw pyrolysis liquid is withdrawn through a conduit
(63) until the liquid level reaches the low level mark. Liquid is then accumulated
in the condenser until it reaches the high level mark again when the raw pyrolysis
liquid withdrawal step is repeated.
Non-condensed product vapor is withdrawn from the top of the condenser
(60) by conduit (70) and is fed to a packed second condenser column (72) where
it is further cooled. Liquid is withdrawn by a conduit (74) from the bottom of
the packed second condenser and fed to a pump (76) which pumps it through a water
cooled heat exchanger (78). Cooled liquid product is removed from the heat exchanger
(78) by conduit (80) and is fed to the top of the packed second condenser column
(72). A conventional transparent vertical sight indicator (73) is mounted on the
lower part of the second condenser (72). The sight indicator has high and low liquid
level marks. When the high level mark is reached raw pyrolysis liquid is withdrawn
through conduit (75) until the liquid level reaches the low mark.
A vapor stream is removed from the top of the packed second condenser
column (72) by a conduit (82) and fed through a water cooled heat exchanger (84)
from which it is fed to a conduit (86) which feeds it to a mist eliminator (88).
The vapor is fed from the mist eliminator (88) to a conduit (90) which delivers
the vapor to a filter (92). Liquid is removed from the bottom of the filter (92)
by means of a conduit (102) and recirculated to the bottom portion of the second
condenser column (72) above the level of liquid in the column. A portion of the
resulting clean by-product gas stream is ducted from the filter (92) by a conduit
(94) to waste while a further portion is taken from the conduit (94) and fed to
conduit (96) which feeds it to a gas recirculation blower (98). The recirculated
gas is fed from the blower (98) to a conduit (100) which feeds it into the bottom
of the reactor (44).
The following examples are presented to further illustrate the invention.
In the examples, the concentration values for the organic components in the described
liquids are given as °Brix values. The °Brix values were obtained using standard
refractory techniques which are well known in the sugar industry. The percent
weight per volume (% wt./vol.) values for hydroxyacetaldehyde were obtained using
gas chromotography and comparing the peak integrations of a sample of a liquid
(diluted if necessary) with peak integrations of a standard curve generated from
a 1-5% serial dilution of hydroxyacetaldehyde in water. Gas chromatograms were
run on a Varian Gas Chromatograph (Model 3300 equipped with a Varian Integrater
Model 4290) fitted with a fused-silica capillary column (either a 0.25mm x 60m
J&W DB1701 column or a 0.25mm x. 30m J&W DB-Wax column) using hydrogen
carrier gas at a flow rate of 2.0 ml/mm and a temperature program of 40°C initial
temperature, zero minute hold followed by increasing the temperature at 8.0°C/minute
to 255°C. The injector temperature was 220°C, the detector temperature was 300°C.
Under these conditions, the retention time of hydroxyacetaldehyde
in the J&W DB-1701 column was 2.85 minutes and on the J&W DB-Wax column
was 4.70 minutes.
Dextrose (Cerelose® dextrose 2001, D.E. 95, Corn Products, Inglewood
Cliffs, New Jersey) was fast pyrolyzed at about 550°C using an apparatus as illustrated
in Fig. 4 with a vapor residence time of 0.7 seconds at a pressure of 1-1.5 psi.
The vapors were condensed by direct contact with 20°C recirculating water. About
five pounds of dextrose were fed to the apparatus over a twenty minute period.
The resulting raw pyrolysis liquid was found to have a Brix value
of about 4° and to contain about 0.5 % wt./vol. hydroxyacetaldehyde. The solution
was then concentrated at 50°C under a water aspirator vacuum of about -28.5 inches
of mercury to remove excess water to give a solution of about 63° Brix and a hydroxyacetaldehyde
concentration of about 29 % wt./vol.
Powdered dextrose was pyrolyzed in a downflow transport reactor (Fig.
1) using sand as the heat transfer media. The reactor temperature was 600°C and
the vapor residence time in the reactor was 75 msec. The pyrolysis liquid yield
was 83.5%, noncondensable gases yield was 14% and char yield was 2.5%. The composition
of the condensed raw pyrolysis liquid was as follows:
Other organics (including hydroxymethyl furfural)
The initial 4° Brix pyrolysis liquid obtained in Example 1 was concentrated
by evaporation under reduced pressure to give a 18° Brix solution containing about
5 % wt./vol. hydroxyacetaldehyde. A portion of this solution (60 ml) was extracted
with three portions of food grade methylene chloride (20 ml) to remove flavor
components. The extracted solution was then treated batchwise with two types of
food grade resins, first with the Rohm & Haas nonionic resin XAD-4 (6 g) and
then with the Rohm & Haas cationic resin IR-120 (3 g) to remove additional
flavor constituents. The resulting solution (about 12.9° Brix) was evaporated to
about 50° Brix to remove low molecular weight volatile components and residual
methylene chloride. The concentrated solution contained about 32 % wt./vol. hydroxyacetaldehyde.
Subsequently, the concentrate was diluted with water back to 13° Brix, which is
a suitable concentration for direct application to a foodstuff.
The 13° Brix solution containing about 5 % wt./vol. hydroxyacetaldehyde
was applied to the surface of Swift Premium Brown and Serve Sausages (Swift -
Eckrich, Inc., Oak Brook, Illinois). The sausages were microwaved along with untreated
sausages which were used as a control. After microwaving the sausages treated
with the browning solution had a rich golden brown color compared to the untreated
control sausages which had a greyish white color. There was no palatable difference
in terms of flavor between the two groups of sausages. This shows that the flavorless
browning solution browned the sausages without also contributing a detectable
flavor to the sausages.
This example describes a method for producing a high browning, flavorless
liquid product from dextrose and its usefulness in browning foods in a microwave
Dextrose was fast pyrolyzed at about 550°C in an upflow circulating
fluidized bed reactor as illustrated shown in Fig. 4. The vapor residence time
was about 0.7 second, the pressure was about 1-1.5 psi and the pyrolysis vapors
were condensed and solubilized by direct contact with circulating 20°C water. The
resulting aqueous condensate solution contained about 4° Brix total organic solids
as determined by refractive index and about 0.5 % wt./vol. hydroxyacetaldehyde
as determined by gas chromatography. This solution was then concentrated to 18°
Brix organic solids by rotary evaporation and was found to contain about 6 % wt./vol.
hydroxyacetaldehyde. A portion of this solution (60 ml) was then extracted with
three portions of food grade methylene chloride (20 ml) to remove flavor components.
The solution was then concentrated to 50° Brix organic solids to remove low molecular
weight flavor components. This solution was found to contain 23 % wt./vol. hydroxyacetaldehyde
by gas chromatography. Gas chromatography analysis also showed that furfural,
phenolics, and pyrazines were the major flavor components removed by the extraction
and evaporation. Water was then added to dilute the solution back to 5 % wt./vol.
hydroxyacetaldehyde and the organic solids content was found to be 12° Brix.
This diluted flavorless foodstuff browning solution was applied to
the surface of Swift Premium Brown and Serve Sausages. The sausages were microwaved
for two minutes along with untreated sausages which were used as a control. After
microwaving the sausages treated with the browning solution had a rich golden
brown color compared to the control sausages which had a greyish white color. There
was no palatable difference in terms of flavor between the two groups of sausages.
This shows that the flavor less browning solution browned the sausages without
also contributing a detectable flavor to the sausages.
This example describes a method for producing a high browning, flavorless
liquid product from lactose.
Lactose was pyrolyzed in a circulating fluidized bed reactor, capable
of processing about 100 lbs/hr of solid feedstock, at 500°C. in an upflow circulating
fluidized bed reactor described in connection with Fig. 4. The vapor residence
time in the reactor was about 0.7 second, the pressure was about 1-1.5 psi and
the pyrolysis vapors were condensed by direct contact with circulating 20°C water
as described in Example 1. The resulting condensate solution, or raw pyrolysis
liquid, contained about 2° Brix total organic solids as determined by refractive
index. The hydroxyacetaldehyde concentration was 0.11%, the acetic acid content
was less than about 0.01% and the acetol content was about 0.06% as determined
by analytical gas chromatography. The solution was then concentrated by evaporation
at 50°C under a vacuum of -29 inches mercury to 26° Brix organic solids including
4 % wt./vol. hydroxyacetaldehyde. The concentrated solution (60 ml) was extracted
with three portions of food grade methylene chloride (20 ml) to remove flavor components
such as furfural, phenolics and pyrazines. The extracted solution was then concentrated
to 50° Brix organic solids to remove low molecular weight flavor components. This
solution was found to be 11 % wt./vol. hydroxyacetaldehyde. The solution was then
diluted with water back to 5 % wt./vol. hydroxyacetaldehyde and was found to contain
19° Brix organic solids.
This diluted flavorless food browning solution was applied to the
surface of Swift Premium Brown and Serve Sausages by dipping the sausage into the
solution for two to three seconds and then allowing the sausage to drip dry for
thirty seconds. The sausages were microwaved along with untreated sausages which
were used as a control. After microwaving the sausages treated with the browning
solution had a rich golden brown color compared to the control sausages which had
a greyish white color. There was no palatable difference in terms of flavor between
the two groups of sausages. This shows that the flavorless browning solution browned
the sausages without also contributing a detectable flavor to the sausages.
This example shows a second method for producing a high browning,
flavorless liquid solution from dextrose and its usefulness in browning a foodstuff
cooked in a microwave oven.
Dextrose was pyrolyzed according to the method of Example 4 and the
resulting aqueous solution was concentrated to 18° Brix organic solids and 6 %
wt./vol. hydroxyacetaldehyde. A portion of this solution (60 ml) was then treated
batchwise with two types of food grade resins, first with the Rohm and Haas non-ionic
XAD-4 resin (6 grams) and then with the Rohm and Haas cationic IR-120 resin (3
grams) to remove flavor components. The solution after resin treatment was found
to contain about 13° Brix organic solids by refractive index. It was then concentrated
to about 50° Brix organic solids by evaporation to remove low molecular weight
flavor components. Gas chromatography analysis showed that this solution contained
23 % wt./vol. hydroxyacetaldehyde and that furfural, phenolics and pyrazines were
the major flavor constituents removed by the resin treatment and evaporation. The
solution was then diluted back with water to 5 % wt./vol. hydroxyacetaldehyde
and found to have about 12° Brix organic solids.
This diluted flavor less food browning solution was applied to the
surface of Swift Premium Brown and Serve Sausages. The sausages were microwaved
along with untreated sausages which were used as a control. After microwaving
the sausages treated with the browning solution had a rich golden brown color compared
to the control sausages which had a greyish white color. There was no palatable
difference in terms of flavor between the two groups of sausages. This shows that
the flavor less browning solution browned the sausages without also contributing
a detectable flavor to the sausages.
This example describes removing undesired flavor components from
a liquid product of lactose by methylene chloride extraction.
Lactose was fast pyrolyzed according to the method of Example 5.
The resulting aqueous liquid product was found to contain about 2° Brix total organic
solids by refractive index. This solution was then concentrated by evaporation
at 50°C and -29 inches mercury to about 26° Brix organic solids and then divided
into two portions. One of the portions (100 ml) was extracted with food grade methylene
chloride (3 x 30 ml) and a second portion was not extracted so as to serve as
a control. The organic solids in the extracted portion dropped from 26° Brix to
Each solution was then diluted to 150 ppm organic solids with distilled
water. A triangular taste panel was set up with the following three samples:
Ten taste panelists were asked to pick the odd sample and comment on the flavors.
Seven of the panelists identified Sample A. Comments of the panelists indicated
Sample A had virtually no flavor compared to B and C which both had a mild smoky
flavor. This demonstrates that the methylene chloride extraction was an effective
way to remove flavor components from the lactose pyrolysis liquid.
- A =
- Extracted Diluted Sample
- B =
- Not Extracted Diluted Sample
- C =
- Not Extracted Diluted Sample
This example describes a method of producing a liquid product from
A sample of FRO-DEX-24-D (Amaizo Co., Hammond, Indiana), a powdered
starch containing 6% moisture and having a 26% dextrose equivalent content was
fast pyrolyzed at about 550°C in an upflow circulating fluidized bed reactor such
as illustrated in Fig. 4. The vapor residence time was about 200 msec. and the
pyrolysis vapors were condensed and solubilized using a cold water condenser.
The resulting condensate solution was found to contain 51° Brix organic solids
by refractive index and 24 % wt./vol. hydroxyacetaldehyde by gas chromatography.
Thus, the hydroxyacetaldehyde concentration was about 50% of the organic solids
of the condensate solution.
This examples describes another method of producing a liquid product
A sample of PF powdered starch (Amaizo Co., Hammond, Indiana) containing
about 12% moisture was fast pyrolyzed at about 550°C in an upflow circulating
fluidized bed reactor. The vapor residence time was about 200 msec. and the pyrolysis
vapors were condensed and solubilized using a cold water condenser. The resulting
condensate solution was found to contain 56° Brix organic solids by refractive
index and 29 % wt./vol. hydroxyacetaldehyde by gas chromatography. Thus, the hydroxyacetaldehyde
concentration was about 50% of the organic solid of the condensate solution.
This example describes a method of producing a high browning, flavorless
liquid product from corn syrup.
High dextrose corn syrup having 83.7% total solids and 16.3 % moisture
(62 D.E./44 Baume' corn syrup, ADM Corn Sweetners Cedar Rapids, IA.) was heated
to about 150°F and then pumped through steam heated conduits into an upflow circulating
fluidized bed reactor illustrated in Fig. 4. The heated corn syrup enter the reactor
through a nozzle having a 3/32 inch aperture. The reactor temperature was about
550°C, the vapor resident time was about 700 m sec. and the pressure was about
1.5 psi. The pyrolysis vapors were condensed and solublilized by direct contact
with 20°C recirculating water to give a liquid product having about 30° Brix.
The compositions of the liquid product was as follows:
The 30° Brix solution was extracted with methylene chloride (one
volume methylene chloride to ten volumes solution) and then concentrated by evaporation
under reduced pressure (-28.5 inches of mercury) at about 50°C to give a liquid
product of about 45° Brix.
The corn syrup derived liquid product of Example 10 was diluted with
water to about 23° Brix and compared to four different pyrolysis liquid samples:
1) a methylene chloride extracted slow pyrolysis commercially available liquid
smoke made according to the procedure described in U.S. Patent 4,717,576 to Nicholson
(Briefly, CHARSOL C-12, 500 ml 28° Brix, 12% titratable acidity, browning index
12, Red Arrow Products Company Inc. was extracted with methylene chloride, 50
ml, to give a liquid smoke of about 23° Brix); 2) a fast pyrolysis product of Avicel
pH 101 cellulose made according to the procedure described in Example 8 of U.S.
Patent No. 5,039,537 issued 08/13/91.
3) a fast pyrolysis product or maple sawdust treated by contact
with a XAD-4 nonionic resin made according to the procedure described in Example
6 of U.S. Patent No. 5,039,537
and 4) a fast pyrolysis product of dextrose the values were calculated
from the data in Example 2, above, in direct proportion to °Brix values.
Comparative physical properties of the five liquid products are illustrated
in Table 3.
*Values calculated according to
the procedures described by Nicholson. U.S. Patent 4,717,576
Titratable Acidity/Browning Index (B.I.)
Case Browning* Density B.I./cm2
CHARSOL C-12 (methylene chloride extracted)
AVICEL pH 101
HARDWOOD XAD-4 resin extracted
CORN SYRUP (methylene chloride extracted)
The case browning index shown in Table 3 is a measure of the browning
ability of a casing treated with a liquid composition. The calculation according
to the procedure described by Nicholson, US-Patent No. 4,717,576, will become more
clear by the following sample calculation for CHARSOL C-12 (first example in Table
The case browning density was determined using a casing loading of
5.87 mg/cm2 of concentrated liquid smoke, as disclosed in Table H and
lines 45 to 55 in column 26 of US-Patent No. 4,717,576. The loading factor of 5.87
mg/cm2 relates to a concentrated CHARSOL C-12 product (i.e., a product
that is concentrated by a factor of 4). A loading factor of 5.87 mg/cm2
uses a concentrated product corresponding to a loading factor of 1.4 mg/cm2
for unconcentrated CHARSOL C-12, i.e., 5.78 mg/cm2 4.
Unconcentrated CHARSOL C-12 (1.0 ml or 1.096 g) has a browning index
of 12, as determined by the procedure set forth in US-Patent No. 4,717,576 at column
21, lines 27 to 65. Therefore, unconcentrated CHARSOL C-12 has a casing browning
1096 mg C-12 / (12 B. Index) = 1.4 mg C-12/cm 2 / (x B.
Index/cm 2) ; X=0.015 B.I./cm 2
This is the value shown in Table 3. Calculation of the other values
The above data indicated that the liquid product prepared according
to Example 10 has a significantly higher casing browning density value compared
to commercial liquid smoke treated by the method disclosed by Nicholson. In addition,
the pyrolysis of sugars and starches provides a liquid product with a significantly
reduced acidity. Such low acidity liquid products are particularly preferred for
applications to food casing because casings are susceptible to degradation at
low pH values.
The foregoing detailed description has been given for clearness of
understanding only, and no unnecessary limitations should be understood therefrom,
as modifications will be obvious to those skilled in the art.