Mold and dust inhibiting product and method

A mold and dust inhibiting composition which has particular utility in connection with the use of animal litter such as poultry litter, as well as having general utility for controlling both mold and dust. The composition of the invention is an aqueous solution of one or more salts of propionic acid, one or more deliquescent substances, and also preferably one or more humectants. Propionate ions are made available for mold control by this solution just as effectively as propionic acid, but without the disadvantages of propionic acid including a bad odor, serious corrosive characteristics, and high volatility and hence short residual time. The deliquescent, and preferably also the humectant, prevent moisture from migrating toward container walls where there is a large day/night temperature differential, and also prevent dry regions from developing and producing potentially harmful dust. Addition of lecithin to the product as a lubricant provides additional protection against dust being generated.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention is in the field of mold inhibitors, and also relates 
to the prevention of harmful dust which is likely to be generated in the 
handling and use of some products which also characteristically have mold 
problems, such as animal feeds and grains, and poultry litter. 
2. Description of the Prior Art 
a. Mold Problems 
There is a serious worldwide problem of molds growing in food materials, 
and particularly in animal feeds. This problem is most serious, and is a 
year-round problem, in tropical zones of both the eastern and western 
hemispheres, but it is also a problem in temperate and colder zones, 
particularly during the spring and fall seasons when there are frequently 
large temperature differentials between night and day, on the order of 
30.degree. F. or more, which can cause an accumulation of moisture in the 
feed adjacent the cold metal of feed tanks or bins. 
One reason molds present such a serious problem is that they produce 
dangerous mycotoxins, some of which are carcinogenic. For example, one of 
the common molds, Aspergillus flavus, produces the mycotoxin aflatoxin 
which, in addition to other toxic characteristics, interferes with the 
immune system's ability to produce gamma globulin, the protein that is 
part of the immune system. The resulting breakdown of the immune system 
then renders animals that have ingested such mold vulnerable to a variety 
of diseases. 
The standard product that has been used for many years for the control of 
molds is propionic acid CH.sub.3 CH.sub.2 COOH. Prior to the present 
invention, propionic acid has been the most reliable mold inhibitor for 
animal feeds, and it still remains the product of choice on a worldwide 
basis. 
However, propionic acid has serious problems, so that it is unacceptable in 
many circumstances, and its use will be limited in some areas of the 
world, particularly in the Orient where the mold problem is severe. A 
major problem with propionic acid is that it has a terrible, strong odor, 
which is almost like the smell of urine, and when people work around 
propionic acid, their clothes and bodies acquire this obnoxious odor. One 
reason for this bad odor is that it is very volatile, so that it is 
rapidly released in vapor form from feeds to which it has been applied. 
For this reason, many people, and the people of some regions such as the 
Orient, will not stand for the use of propionic acid; and those who do use 
it are uncomfortable in such use. Also, some animals, particularly hogs, 
are especially sensitive to the odor of propionic acid. 
Another serious problem with propionic acid is that it is highly corrosive. 
The only feasible place for propionic acid to be applied to feeds is in 
feed mill equipment, and this equipment is generally made of mild steel 
which is particularly vulnerable to acid corrosion. Thus, feed mill 
equipment in which propionic acid is added to the feeds will rapidly 
deteriorate from the attack of this acid. 
A further serious problem with the use of propionic acid is that it has a 
high degree of volatility and hence short residual time. 
A number of mold inhibitor products combining propionic acid with other 
ingredients such as acetic acid and benzoic acid have been and are 
currently being marketed under a variety of trademarks in an endeavor to 
make the products more commercially acceptable, but the principal 
operative ingredient of such products is still propionic acid, and such 
products still have the same problems of the odor and corrosiveness of 
propionic acid. 
It has been understood in the art that it is the propionate ion CH.sub.3 
CH.sub.2 COO-- that is the active mold inhibitor ingredient in propionic 
acid, so attempts have been made to use salts of propionic acid as mold 
inhibitors in an endeavor to overcome the odor and corrosion problems. The 
principal salts that have been used are the sodium and calcium salts of 
propionic acid, and as far as applicant is aware, these have only been 
used as mold inhibitors in a fine, granular form, and never in the form of 
a liquid solution. These propionate salts do not have an objectionable 
odor, and are neutral and hence not especially corrosive. The sodium 
propionate salt has been found satisfactory in solid form for human use in 
bread, this being made possible because the granular or powdered sodium 
propionate disperses fairly well in the wet bread dough, remaining well 
dispersed throughout the baked bread. 
Although currently used to a limited extent in animal feeds, the dry 
propionate salts are not satisfactory for feeds, the principal problem 
being that in granular form there is insufficient contact of the 
propionate salt particles with the grain particles unless great quantities 
of the propionate salts are used. On the order of five to seven times as 
much of the propionate salt must be used in order to disperse it 
adequately through the feed to get approximately the same degree of mold 
inhibition as can be achieved with liquid propionic acid. This makes the 
use of dry propionic salts such as sodium propionate and calcium 
propionate economically disadvantageous as mold inhibitors for animal 
feeds. 
Prior to the present invention, propionic acid salts have never been usable 
in the form of a liquid solution for treating animal feeds, even though 
they would be equally as effective for mold inhibiting as propionic acid 
because it is the propionate ion which performs the mold-inhibiting 
function, and the liquid would be readily dispersable in intimate contact 
with the feed grain particles in the same relatively small amounts as with 
liquid propionic acid, but without the objectionable odor and corrosive 
characteristics of the acid. It is believed that a reason liquid propionic 
salt solutions have not heretofore been used as animal feed mold 
inhibitors is the great propensity of the propionic salts to precipitate 
out of the solution in a mushy, gel-like form. Even though adequate 
concentrations might have been achievable under controlled laboratory or 
plant conditions, the long-term stability would have been unreliable for a 
useful mold-inhibiting product. 
Another mold problem of which applicant is aware associated with the 
handling of animals is in poultry litter. Poultry litter is conventionally 
composed of wood shavings, rice hulls and the like spread out to 
approximately a 6-inch depth under the poultry. This mold problem is most 
severe around the poultry feeders where moisture tends to accumulate from 
droppings from the birds. 
b. Dust Problems 
There are also serious dust problems in connection with the use, handling, 
and storage of some of these same materials for which there are mold 
problems as described above. 
One such dust problem of which applicant is aware that occurs in connection 
with animal feeds relates to poultry feed. The tips of poultry feed 
granules have a tendency to dry out and break off from the feed granules 
and turn into dust. Such dust when breathed in by the birds can cause 
serious respiratory diseases such as Aspergillosis. This same problem 
occurs with respect to the wood shavings, rice hulls and the like used for 
poultry litter. The litter tends to dry out and generate dust which, when 
breathed in by the birds, can cause the same diseases as feed dust. 
SUMMARY OF THE INVENTION 
In view of these and other problems in the art, it is a general object of 
the present invention to provide a liquid mold inhibitor that is as 
effective as propionic acid, but does not have the objectionable odor, 
corrosion problems, and high volatility and hence short residual time 
characteristic of propionic acid, and which is therefore particularly 
useful for controlling mold. 
Another general object of the present invention is to provide a liquid mold 
inhibitor which, because of its effectiveness and lack of objectionable 
characteristics, will be acceptable in all areas of the world, and most 
importantly, in those tropical areas where mold is a serious problem but 
propionic acid will often not be used because of its bad odor and 
corrosive charateristics. 
Another object of the invention is to provide a liquid mold inhibitor which 
comprises an aqueous solution of a salt of propionic acid, which may be 
one or more of three propionate salts, ammonium propionate, sodium 
propionate, and potassium propionate. 
Another object of the invention is to provide a propionate salt solution 
mold inhibitor which includes deliquescent material, preferably one or 
more deliquescent substances from the group consisting of magnesium 
chloride, calcium chloride, manganese chloride, ferric chloride, and zinc 
chloride, the deliquescent material holding water in the treated product 
to maintain hydrolyzation and hence effectiveness of the propionate ion 
content of the treated product, and serving the surprising function of 
preventing treated materials from becoming overly damp near the walls of 
containers subject to large overnight temperature differentials. 
Another object of the invention is to provide a liquid propionate salt 
solution mold inhibitor of the character described which includes one or 
more humectants, preferably from the group consisting of glycerol, 
potassium polymetaphosphate, propylene glycol, sorbitol, triacetin, 
mannitol, pectins, and polyhydric alcohols, the humectant trapping 
odor-carrying moisture molecules in the liquid solution, and also 
cooperating with the deliquescent material in keeping the water content of 
the solution up so that the propionate salt remains fully hydrolyzed and 
thereby fully functional as a mold inhibitor, and additionally cooperating 
with the deliquescent material in preventing water molecules from 
migrating through containers and concentrating proximate cold container 
walls. 
A further general object of the invention is to provide a novel aqueous 
mold-inhibiting solution which also surprisingly and synergistically has 
excellent dust-inhibiting characteristics, whereby the same aqueous 
solution of the invention when applied to poultry litter or the like will 
function to either inhibit the formation and propagation of mold or 
inhibit the formation of dust, and under some circumstances, will perform 
both of these inhibiting functions with respect to a product treated by 
the invention. 
A further, more specific object of the invention is to provide an aqueous 
solution containing one or more salts of propionic acid, one or more 
deliquescent substances, and also preferably one or more humectants, which 
will function both to prevent the growth of mold and prevent the 
production of dust with respect to treated products. 
A still further object of the invention is to provide a mold and dust 
inhibiting aqueous solution of the character described which, while 
protecting poultry litter against mold, also protects poultry litter 
against the formation of dangerous dust which, when breathed in by birds, 
may cause a respiratory disease such as Aspergillosis. 
Another object of the invention is to enhance the dust inhibiting function 
of the liquid product of the invention, by including a uniformly dispersed 
suspension of feed-grade lecithin in the aqueous solution of the 
invention, the lecithin lubricating against the production of dust by 
abrasion. 
An additional object of the invention is to provide a mold and dust 
inhibiting product which functions over a long residual time. 
The product of the present invention is an aqueous solution of one or more 
salts of propionic acid and deliquescent material, and preferably also 
humectant. The salt of propionic acid may be ammonium propionate, sodium 
propionate, or potassium propionate, or any combination of these three 
propionate salts. The deliquescent material may be one or more of a large 
number of deliquescent substances as set forth hereinafter in the Detailed 
Description, but is preferably one or more deliquescent substances from 
the group consisting of magnesium chloride, calcium chloride, manganese 
chloride, ferric chloride, and zinc chloride. The humectant is preferably 
one or more humectant substances from the group consisting of glycerol, 
potassium polymetaphosphate, propylene glycol, sorbitol, triacetin, 
mannitol, pectins, and polyhydric alcohols. The pH of the aqueous solution 
of the invention is preferably in the range of from approximately 6.3 to 
approximately 6.9, which is a substantially neutral condition of the 
aqueous solution. Such substantially neutral condition minimizes the 
volatility of the propionate ion content of the solution, and thereby 
helps keep odor to an absolute minimum, while at the same time the 
propionate ion content of the solution is fully effective for mold 
control, being just as effective as propionic acid. Because of this 
substantially neutral condition of the solution of the invention, it is 
generally noncorrosive, having corrosive characteristics approximating 
those of water. 
The deliquescent material in the aqueous solution of the invention stops 
water from coming off of the treated product, maintaining hydrolyzation of 
the propionic salt and hence effectiveness of the propionate ion content 
for inhibiting the propagation of mold throughout the product that is 
treated. At the same time, it is believed that by stopping water from 
coming off of the treated product, the deliquescent material thereby also 
stops propionate ions from coming off with the water vapor, which would 
otherwise tend to shorten the residual time or effective operating life of 
the solution of the invention and also tend to cause objectionable odor. 
The presence of the deliquescent material in the solution of the invention 
also prevents dry surface areas from developing in products treated by the 
invention, such as poultry litter, and thereby prevents the generation of 
potentially harmful dust from the treated products. 
The humectant which is also preferably included as a component of the 
aqueous solution of the invention cooperates with the deliquescent 
material in stopping water from coming off of the product, and hence in 
maintaining hydrolyzation of the propionic salt, blocking both water 
molecules and propionate ions from coming off of the treated materials, 
and in preventing the development of dry, dust-producing areas of the 
treated materials. 
While odor control is primarily accomplished by use of propionate salt 
instead of propionic acid, and also by the substantially neutral condition 
of the solution which minimizes volatility of the propionate ion content, 
odor control is also aided by the water molecule-attracting power of the 
deliquescent material, and where humectant is included in the solution, 
the humectant further controls odor by inhibiting the moisture molecules 
from escaping the liquid solution and thereby locking odor-carrying 
moisture in the solution. 
An additional ingredient that may be included in the solution of the 
invention is a substantially uniform dispersion of feed-grade lecithin. 
A still further ingredient that may be included in the solution of the 
invention is monosodium glutamate.

DETAILED DESCRIPTION 
The product of the invention is a mold and dust inhibiting aqueous solution 
which finds particular utility in connection with the use of animal litter 
such as poultry litter, as well as having general utility for controlling 
both mold and dust where humidity and temperature conditions are such as 
to make these a problem. 
Mold problems are conventionally thought of as only being present in damp, 
humid climates. However, applicant has determined that where products are 
stored or transported in metal bins or containers, regardless of the 
humidity wide temperature variations which are likely to occur between day 
and night will often cause moisture migration toward and onto the walls of 
such bins and containers, producing a peripheral concentration of moisture 
which is conducive to mold propagation. 
Dust problems are conventionally regarded as dry, low humidity climate 
problems, and those having ordinary skill in the art would not consider 
the possibility that a product such as the present invention which has 
particular utility for the control of dampness-propagated mold might also 
have particular utility for the control of dust. In the present invention, 
the novel combination of ingredients not only effectively controls the 
propagation of mold, but at the same time, performs what would normally be 
considered an opposite function of effectively controlling dust, and the 
present invention is desirably applied to inhibit and control mold 
propagation and/or dust production regardless of what environments such 
batches may be subjected to, and therefore without any need for 
selectively applying separate mold inhibiting and dust inhibiting measures 
according to projected environments or handlings to which the treated 
material may be subjected. 
The principal combination of the invention is an aqueous solution of a salt 
of propionic acid, which is preferably ammonium propionate, sodium 
propionate, or potassium propionate, or any combination of these, together 
with a deliquescent material, which is preferably one or more deliquescent 
materials from the group consisting of magnesium chloride, calcium 
chloride, manganese chloride, ferric chloride, and zinc chloride. The 
invention also preferably includes one or more humectants from the 
preferred group consisting of glycerol, potassium polymetaphosphate, 
propylene glycol, sorbitol, triacetin, mannitol, pectins, and polyhydric 
alcohols. 
Moisture control in the material to which the invention is applied is 
accomplished primarily by the presence of the deliquescent material, and 
involves stabilization of moisture in the product to which the invention 
is applied, both against evaporation and against movement or migration of 
water molecules, as described hereinafter in detail. When humectant is 
combined in the product of the invention, it cooperates with the 
deliquescent material in controlling moisture against evaporation and 
migration by blocking the escape of water molecules from the protected 
product, and is also particularly useful in controlling odor which has 
historically been a serious problem where propionic acid has been used for 
mold control. 
Applicant's aqueous solution of one or more salts of propionic acid and one 
or more deliquescent materials, and also preferably one or more 
humectants, serves both of the primary inhibiting functions of the 
invention, namely, mold inhibiting and dust inhibiting. Nevertheless, as 
further assurance against the production of potentially explosion-causing 
dust, it is also preferred to include a fatty material, preferably 
feed-grade lecithin, as a substantially uniformly dispersed suspension in 
the aqueous solution, the lecithin or other fatty material cooperating 
with the other ingredients as a positive assurance against the production 
of dust in this situation. 
An additional ingredient that may be included in the aqueous solution of 
the invention is monosodium glutamate (MSG). 
By employing one or more salts of propionic acid instead of the 
state-of-the-art mold inhibitor propionic acid per se, the solution of the 
present invention is enabled to be made close to neutral, with a preferred 
pH of approximately 6.6, and a preferred pH range of from approximately 
6.3 to approximately 6.9, instead of highly acidic as is propionic acid, 
and this in turn makes the solution much less volatile than propionic 
acid, which reduces the odor, and also makes the solution generally 
noncorrosive, having corrosive characteristics approximating those of 
water. A series of factors which determine this preferred pH and preferred 
pH range are described in detail hereinafter. The salt or salts of 
propionic acid embodied in the invention nevertheless have substantially 
the same mold-inhibiting effectiveness as propionic acid, but without its 
three major objectionable features, namely, disagreeable odor, highly 
corrosive characteristics, and high volatility and hence short residual 
time. Thus, the propionate salt component of the present invention gives 
the invention the same utilitarian capability as propionic acid, without 
its objectionable features, and thereby makes the invention acceptable for 
mold control in all areas of the world, and most importantly in those 
humid tropical areas where mold is a severe problem but propionic acid 
will not be used because of its bad odor, corrosive characteristics, and 
short residual time. 
While all three salts of propionic acid, sodium, ammonium, and potassium, 
or any combination of the three, are satisfactory for the present 
invention, as will be appreciated from test data set forth hereinafter, 
ammonium propionate is presently preferred because for a selected 
percentage by weight of the deliquescent material or materials in the 
formulation, a relatively greater, and hence more effective, percentage by 
weight of propionate ions can be included in the formula. Next preferred 
is potassium propionate, because for a selected percentage by weight of 
deliquescent material, the next largest percentage by weight of propionate 
ions can be included in the formula. Least preferred of the three 
propionate salts is sodium propionate, because for a selected percentage 
by weight of deliquescent material, the least percentage by weight of 
propionate ions can be included in the formula of the three propionate 
salts. 
For similar reasons, the most preferred deliquescent materials from the 
preferred group consisting of magnesium chloride, calcium chloride, 
manganese chloride, ferric chloride, and zinc chloride, are magnesium 
chloride, ferric chloride, manganese chloride, and zinc chloride, while 
the least preferred of these five deliquescent materials is calcium 
chloride. For a selected percentage by weight of these preferred four 
deliquescent materials, a larger percentage by weight of effective 
propionate salt is enabled to be included in the formula than can be 
included where calcium chloride is the selected deliquescent material. 
Test data supporting such selection is set forth in detail hereinafter. 
Of the preferred group of humectants consisting of glycerol (glycerine), 
potassium polymetaphosphate, propylene glycol, sorbitol, triacetin, 
mannitol, pectins, and polyhydric alcohols, the presently preferred 
humectant is glycerol because of its widespread availability and 
acceptance as a food ingredient. 
The presence of the deliquescent material in combination with the salt of 
propionic acid in applicant's aqueous solution provides a plurality of 
cooperative functions which, at least in part, are unexpected and 
surprising, and contrary to what those skilled in the art would expect. 
The strong attraction of the deliquescent component of the invention 
effectively stops water from evaporating from or coming off the poultry 
litter, or other treated product to which the present invention has been 
applied. (1) Thus, the deliquescent material prevents a reduction of 
moisture in the treated product which would in turn reduce hydrolyzation 
of the propionate salt which is necessary for maintaining the active 
condition of the propionic ions for performing the mold inhibiting 
function. (2) Also, the deliquescent material in the solution of the 
present invention bars evaporation of water molecules from relatively warm 
zones and migration of such evaporated water molecules toward relatively 
cold zones such as bin or container walls under climatic conditions where 
there is a relatively large temperature differential between day and 
night, preventing moist, mold-propagating zones from being generated 
adjacent container walls during storage and transport of such treated 
materials. (3) Further, it is believed that the deliquescent material, by 
inhibiting escape of water vapor from the treated products, stops 
propionate ions from coming off of the treated products with water vapor 
which would reduce the propionate concentration and hence the 
mold-inhibiting strength of the treatment, and which would also tend to 
cause objectionable odor. (4) Presence of the deliquescent material in the 
solution of the invention prevents dry, dust-producing surface zones from 
developing on poultry litter and the like by evaporation of moisture from 
such surface portions, preventing the production of dust which might be 
harmful when breathed in by animals such as poultry, or which might result 
in calamitous, explosive atmospheres in storage regions. (5) Further, the 
deliquescent material tends to equalize moisture or make moisture more 
uniform throughout the treated product by providing a relatively greater 
affinity for moisture in relatively drier regions of the product than in 
relatively wetter regions of the product, tending to reduce unwanted zones 
of high moisture concentration such as in litter under poultry feeders, 
minimizing mold-propagating moisture concentrations. 
While the presently preferred deliquescent material is one or more 
deliquescent substances from the group consisting of magnesium chloride, 
calcium chloride, manganese chloride, ferric chloride, and zinc chloride, 
nevertheless the deliquescent material may be any one or more deliquescent 
chemicals from the group consisting of ammonium citrate, calcium chlorate, 
calcium chloride, calcium iodide, calcium nitrite, cobaltous ammonium 
chloride, cobaltous iodide, cupric chlorate, cupric nitrate, ferric 
chloride, ferric lactate, ferric nitrate, ferrous iodide, magnesium 
ammonium chloride, magnesium chlorate, magnesium chloride, magnesium 
iodide, magnesium nitrate, magnesium potassium chloride, chloride, 
manganese oxide, manganese sulphate, phosphoric acid, phosphorus oxide, 
potassium acetate, potassium carbonate, potassium iodide, potassium 
phosphate, sodium bisulphate, stannic sulphate, and zinc chloride. 
The humectant or combination of humectants preferably included in the 
product of the present invention have the characteristic of opposing or 
blocking escape of water molecules from materials to which the present 
invention is applied, such as feeds, grains, or poultry litter, and by 
virtue of such function, the humectant or humectants cooperate with the 
deliquescent material in maintaining hydrolyzation of the propionic salt, 
avoiding the development of dry zones in the treated material, preventing 
evaporation of moisture from relatively warm zones so that it might be 
able to migrate to relatively cold zones, and in preventing propionate 
ions from coming off with water vapor which would tend to reduce the 
mold-inhibiting strength of the product and also tend to cause odor from 
released propionate ions. 
The great reduction of odor achieved by the present invention appears to be 
the result of a synergistic cooperation between the substantial 
neutralization of propionic acid and the presence of both the deliquescent 
component of the solution and the humectant component of the solution. The 
substantially neutral propionic salt solution has a much lower volatility 
than propionic acid, which greatly reduces the evaporation of 
odor-carrying moisture to a sufficiently low level for the deliquescent 
material and the humectant to be able to substantially completely "lock 
in" the odor. A humectant has heretofore been used by applicant for 
control of evaporation, but applicant is not aware of any prior use of a 
humectant, or of a deliquescent material, coupled with neutralization for 
odor control, or of any such use for animal feed. In applicant's prior 
U.S. Pat. No. 4,008,332, issued Feb. 15, 1977 for "Microcide," a humectant 
and a deliquescent were used to prevent evaporation of a very thin film of 
microcide-containing moisture on a relatively short-term basis, unrelated 
to odor control. 
The propionate salt solution of the present invention is produced by mixing 
propionic acid with base which may be ammonium hydroxide, sodium 
hydroxide, potassium hydroxide, or a mixture of any two or more of these 
three bases. The quantity of base relative to the propionic acid is 
adjusted to provide the desired pH. The pH of the present mold-inhibiting 
product solution is preferably in the range of from approximately 6.3 to 
approximately 6.9, which, although slightly acidic, is a substantially 
neutral state. The presently preferred pH for the product of the invention 
is approximately 6.6. There is a series of factors which form the basis 
for such preferred and most preferred pH ranges for the present invention. 
One such factor is that applicant has found that this preferred range is 
optimal for the effectiveness of propionic acid salt in controlling most 
molds. The propionic acid salt disassociates with maximum effectiveness in 
the aqueous solution within the pH range of approximately 6.3 to 
approximately 6.9, and it is the propionate ion which does the job of mold 
control. A second factor that applicant has found in having his preferred 
range of pH from about 6.3 to about 6.9 is that within this range, the 
solution is not substantially more corrosive than water, and this is 
important because the aqueous solution of the present invention is 
primarily applied to vegetable materials housed in mild steel containers. 
A third factor of importance relative to pH is that the lower the pH below 
approximately 6.3, the more volatile the propionate ions become, with 
consequent evaporation and loss of strength of applicant's solution for 
its intended purpose of mold inhibition, and also increased odor. 
The ability of the liquid product of the invention to effectively inhibit 
the production of dust in connection with the use and handling of poultry 
litter is a surprising and synergistic functional addition to the 
mold-inhibiting capability of the product. The dust-inhibiting function of 
the product is important in several specific environmental situations of 
which applicant is aware. There are two separate sources where dust is 
commonly generated in the production of poultry. First, the tips of 
poultry feed particles dry and break off into dust, and this is breathed 
in by the birds and is a common cause of respiratory disease problems such 
as Aspergillosis. A separate source of dust which is a common cause of 
these same diseases in birds is poultry litter, which is generally in the 
form of wood shavings, rice hulls and the like. The litter is periodically 
rototilled, but nevertheless areas of the litter commonly dry out and 
become dusty, and when such dust is breathed in by the birds, it is likely 
to cause respiratory diseases such as Aspergillosis. When the poultry 
litter is sprayed with the liquid product of the invention, the 
deliquescent material in the product, and also preferably the humectant in 
the product, cause the moisture to be locked into the product, preventing 
moisture from evaporating off of surface portions of the litter. The 
result is that dust cannot be generated from the litter. At the same time, 
the liquid product of the invention protects the litter against mold where 
conditions are such that mold might otherwise propagate. 
Applicant has discovered that a sufficient proportion of feed-grade 
lecithin can be uniformly dispersed in the aqueous solution of the 
invention to perform the surface lubricating function conventionally 
accomplished by adding fats. Lecithin is a waxy phospholipid or 
phosphatide, and applicant has found that up to one part feed-grade 
lecithin to four parts of applicant's liquid product can be uniformly 
dispersed in colloidal suspension in the aqueous solution. The lecithin 
has two advantages over fats. First, it does not require a separate 
emulsifier to be placed in a stable, uniformly dispersed suspension in the 
aqueous solution of the invention. Second, lecithin is a hygroscopic 
substance, and therefore tends to cooperate with the deliquescent material 
and humectant in their moisture and odor control functions. 
If a fatty substance other than lecithin is embodied in the aqueous 
solution of the invention to assist in dust suppression, it will normally 
require use of a conventional emulsifying procedure in order to be placed 
in uniformly dispersed suspension in the solution. 
The dust problem pertaining to poultry litter and the solution of such 
problem by use of the present invention were described above. There is 
also a mold problem in the use of poultry litter, which is conventionally 
wood shavings, rice hulls and the like, in general around feeders where 
liquid excrement tends to accumulate. Substantially uniform application of 
the liquid product of the invention to poultry litter completely solves 
this problem by the strong mold-inhibiting quality of the invention. The 
excellent odor control characteristic of the invention is important in the 
use of the invention with poultry litter because the large area over which 
the litter is spread and the fluffy, porous nature of the litter exposes a 
very large overall surface area to the atmosphere within the confines of 
the poultry housing area. Use of the conventional propionic acid mold 
inhibitor for this purpose would be virtually impossible because of the 
terrible odor which would accumulate. Despite such large exposed surface 
area of poultry litter, the moisture retention and odor suppression 
characteristics of the invention enable excellent mold-inhibiting 
characteristics to be maintained over an extended useful life of the 
litter without objectionable odor from the product of the invention. 
With the product of the invention substantially uniformly dispersed 
throughout the litter, the invention tends to maintain a generally uniform 
moisture distribution throughout the litter. Where added moisture tends to 
accumulate around feeders, the mold-inhibiting quality of the invention 
has been found with repeated applications of the invention to be strong 
enough to prevent formation or propagation of mold in such regions. 
Applicant has found that to assure long-term protection against mold and 
dust in most environments, 2-4 lbs. per ton of the liquid mold and dust 
inhibitor of the invention should be used for a moisture content of up to 
14 percent by weight; and that for every 2 percent increase in moisture 
over 14 percent, one lb. per ton more of the product should be added. 
Thus, 3-5 lbs. per ton of the product should be used for a moisture 
content of 14-16 percent, 4-6 lbs. per ton for a moisture content of 16-18 
percent, and 5-7 lbs. per ton for a moisture content of 18-20 percent. For 
severe mold problems, considerably more of the product of the invention 
may be desirable. For example, in the most severe mold problem of which 
applicant is aware, it may be desirable to use up to approximately 10 lbs. 
of the liquid product of the invention per ton. 
Where feed-grade lecithin is employed in suspension with the invention, 
that will represent an additional weight of product per ton, preferably 
approximately one part by weight of lecithin to four parts by weight of 
the liquid product of the invention. 
Limits and Proportions of the Ingredients 
Upper Limits for Propionate Ions 
In the following description, percentages by weight for propionate ion 
content in solutions of the invention are given as percentages by weight 
equivalent of propionic acid, of which 98.65 percent by weight is 
propionate ion. 
In general, it is preferred that close to the maximum possible propionate 
ion content be provided in the product of the invention for maximum 
effectiveness in the function of mold inhibition, while still being a 
totally stable product under forseeable weather conditions (i.e., no 
material amount of the product being likely to precipitate out), and at 
the same time, enabling the presence of sufficient deliquescent material 
for efficient operation of the product both as a mold inhibitor and as a 
dust inhibitor, which includes efficient operation of the product in its 
water anti-migration function. 
2.7 percent by weight is a desirable percentage of deliquescent material 
for a highly effective product according to the invention, being a 
sufficient amount to assure against loss of moisture and consequent dust 
problems in very dry climates and to assure against moisture migration 
where there are likely to be very wide day/night temperature variations 
and moisture migration would otherwise be a serious problem. With 2.7 
percent by weight deliquescent material, where the salt of propionic acid 
is ammonium propionate, the maximum weight equivalent of propionic acid 
(of which 98.65 percent by weight is propionate ion) which applicant has 
been able to place in a stable solution of the invention is: 
59% with calcium chloride as the deliquescent; 
68% with magnesium chloride as the deliquescent; 
68% with ferric chloride as the deliquescent; 
68% with manganese chloride as the deliquescent; 
68% with zinc chloride as the deliquescent. 
With sodium propionate as the salt of propionic acid, for 2.7 percent by 
weight deliquescent material, the maximum percent by weight equivalent of 
propionic acid (of which 98.65 percent by weight is propionate ion) which 
applicant has been able to place in a stable solution of the invention is: 
30% with calcium chloride as the deliquescent; 
68% with magnesium chloride as the deliquescent; 
68% with ferric chloride as the deliquescent; 
68% with manganese chloride as the deliquescent; 
68% with zinc chloride as the deliquescent. 
Where the salt of propionic acid is potassium propionate, for 2.7 percent 
by weight of deliquescent material, the maximum percentage by weight 
equivalent of propionic acid (of which 98.65 percent by weight is 
propionate ion) which applicant has been able to place in a stable 
solution of the invention is: 
41.7% with calcium chloride as the deliquescent; 
62.4% with magnesium chloride as the deliquescent; 
68% with ferric chloride as the deliquescent; 
62.4% with manganese chloride as the deliquescent; 
56.8% with zinc chloride as the deliquescent. 
Applicant's testing indicates that where a combination of two or more of 
the ammonium, sodium and potassium salts of propionic acid is employed, 
and where a combination of two or more of the deliquescents calcium 
chloride, magnesium chloride, ferric chloride, manganese chloride, and 
zinc chloride is employed, the amounts of propionate ion and the amounts 
of deliquescent which may be included in a stable solution of the 
invention may be approximately determined by averaging from the specific 
test data set forth above and hereinafter for the particular ingredients. 
Thus, for approximately 2.7 percent by weight of deliquescent material, for 
any of the three propionate salts, ammonium, sodium or potassium, or any 
combination thereof, and for any of the preferred five deliquescent 
materials or any combination thereof, applicant has found that a stable 
solution of the invention can always be formulated with at least 
approximately 30 percent by weight of propionate salt. 
Also, for approximately 2.7 percent by weight of deliquescent material, 
applicant's test data indicates that an upper limit of approximately 68 
percent by weight equivalent of propionic acid may be included in a stable 
solution of the invention by proper selection of the salt of propionic 
acid and the deliquescent material or various combinations thereof. 
It is presently preferred to embody at least approximately 1.0 percent by 
weight of deliquescent material in the solution of the present invention 
to assure adequate mold inhibiting and dust inhibiting functioning of the 
product in various climates, including adequate water anti-migration 
capability. Applicant's tests indicate that approximately the following 
percentages by weight equivalent of propionic acid (of which 98.65 percent 
by weight is propionate ion) can be included in a stable product according 
to the invention where the amount of deliquescent material is 1.0 percent: 
For ammonium propionate as the salt of propionic acid, approximately 64 
percent with calcium chloride deliquescent, and approximately 73 percent 
with magnesium chloride, ferric chloride, manganese chloride, or zinc 
chloride deliquescent materials. 
For sodium propionate as the salt of propionic acid, approximately 35 
percent with calcium chloride deliquescent, and approximately 73 percent 
with magnesium chloride, ferric chloride, manganese chloride, or zinc 
chloride deliquescent materials. 
For potassium propionate as the salt of propionic acid, approximately 46 
percent with calcium chloride deliquescent, approximately 67 percent with 
magnesium chloride or manganese chloride deliquescent, approximately 73 
percent with ferric chloride deliquescent, and approximately 62 percent 
with zinc chloride deliquescent. 
Thus, for approximately 1.0 percent by weight of deliquescent material, for 
any of the three propionate salts, ammonium, sodium, or potassium, or any 
combination thereof, and for any of the preferred five deliquescent 
materials or any combination thereof, applicant's tests indicate that a 
stable solution of the invention can always be formulated with at least 
approximately 35 percent by weight of propionate salt. 
Also, for approximately 1.0 percent by weight of deliquescent material, 
applicant's test data indicates that an upper limit of approximately 73 
percent by weight equivalent of propionic acid may be included in a stable 
solution of the invention by proper selection of the salt of propionic 
acid and the deliquescent material or various combinations thereof. 
To provide a guide for those skilled in the art in the selection of one or 
more of the five preferred deliquescent materials to be included in the 
solution, applicant conducted tests determining the relative proportions 
of each of the five preferred deliquescent materials which could be 
contained in a stable solution product of the invention for a selected 
percent by weight equivalent of propionic acid in the solution. 
With ammonium propionate as the salt of propionic acid, for 55 percent by 
weight equivalent of propionic acid, the following percentages by weight 
of the five deliquescent materials which could be contained in a stable 
solution were: 
Calcium chloride between 4.0 and 5.0 percent 
Magnesium chloride between 7.0 and 8.0 percent 
Ferric chloride between 8.0 and 9.0 percent 
Manganese chloride between 7.0 and 8.0 percent 
Zinc chloride between 9.0 and 10.0 percent. 
With sodium propionate as the salt of propionic acid, and 36.7 percent by 
weight equivalent of propionic acid, the following percentages by weight 
of the five deliquescent materials which could be contained in a stable 
solution were: 
Calcium chloride between 0.5 and 1.0 percent 
Magnesium chloride between 11.0 and 12.0 percent 
Ferric chloride between 0.5 and 1.0 percent 
Manganese chloride between 13.0 and 14.0 percent 
Zinc chloride between 1.0 and 2.0 percent. 
With potassium propionate as the salt of propionic acid, and 30 percent by 
weight equivalent of propionic acid, the following percentages by weight 
of the five preferred deliquescent materials which could be included in a 
stable solution were: 
Calcium chloride between 3.0 and 4.0 percent 
Magnesium chloride between 7.0 and 8.0 percent 
Ferric chloride between 7.0 and 8.0 percent 
Manganese chloride between 8.0 and 9.0 percent 
Zinc chloride between 8.0 and 9.0 percent. 
It is apparent from the foregoing that the use of calcium chloride as the 
deliquescent material places a considerable limitation on the amount of 
propionate ion which can be contained in the solution. Nevertheless, an 
adequate percentage of propionate ion together with an adequate percentage 
of calcium chloride can be embodied in the solution of the invention for 
satisfactory operation of the invention in most circumstances. 
Tests conducted by applicant indicate somewhat better performance of 
calcium chloride as a deliquescent than the other four preferred 
deliquescent materials, at least on a relative short-term basis, which 
appears to be a compensating factor making use of calcium chloride more 
acceptable as the deliquescent material in the present invention. 
Lower Limits for Propionate Ions 
Applicant is not aware of any physical basis for a specific lower limit of 
the percent by weight equivalent of propionic acid to be included in the 
solution product of the invention. Nevertheless, it is presently preferred 
to include at least approximately 20 percent by weight equivalent of 
propionic acid (of which 98.65 percent by weight is propionate ion) to 
assure that the product is effective as a mold and dust inhibitor under 
all conditions of operation. Below approximately 20 percent, the propionic 
salt becomes rapidly functionally and economically ineffective for 
performing its intended functions of inhibiting both mold and dust. It is 
the upper limits of propionic ion content which are important since it is 
preferred to include close to the maximum possible percent by weight of 
propionic ion content in the solution of the invention for maximum 
mold-inhibiting performance of the invention. 
Upper Limits for the Deliquescent Material 
It is preferred to not include more than approximately 10 percent 
deliquescent material in the solution product of the invention. Greater 
than 10 percent deliquescent material undesirably limits the amount of 
propionic ion which may be made available in the formulation, and 
therefore limits the basic mold-inhibiting performance which is available 
from the product. Nevertheless, applicant's tests indicate that up to 
approximately 20 percent deliquescent material may be included in the 
product of the invention without seriously impairing the performance of 
the product, although it would then be necessary to undesirably limit the 
percent by weight of propionate ion available in the product, particularly 
where the deliquescent material is calcium chloride. Any amount greater 
than approximately 20 percent by weight of the deliquescent material would 
be entirely nonutilitarian, and in very humid climates there would be an 
undesirable tendency for the product of the invention to take on moisture 
from the humid atmosphere. 
Lower Limits for the Deliquescent Material 
Applicant has not determined any physical basis for a specific lower limit 
of the percentage by weight of deliquescent material to be included in the 
solution product of the invention. 0.5 percent by weight of deliquescent 
material appears to provide satisfactory operation of the invention for 
most circumstances. At least approximately 1.0 percent deliquescent 
material is presently preferred to assure adequate operation of the 
invention for both mold and dust inhibiting under the various climatic 
conditions where the product is likely to be utilized. At least 
approximately 2.7 percent by weight deliquescent material is a presently 
most preferred amount to assure against loss of moisture and consequent 
dust problems under very dry climate conditions, and to assure against 
moisture migration where very wide day/night temperature variations might 
otherwise tend to cause moisture buildup adjacent container walls. A 
presently preferred amount of deliquescent material in the product is 
approximately 3.6 percent. 
Humectant 
The humectant is preferably any one or more humectants from the group 
consisting of glycerol, potassium polymetaphosphate, propylene glycol, 
sorbitol, triacetin, mannitol, pectins, and polyhydric alcohols. The 
preferred range for the amount of humectant in the product, regardless of 
which one or more humectants may be included, is from approximately 1.0 
percent to approximately 4.0 percent by weight. Within this range, 
applicant has found that the humectant does not appreciably change the 
amounts or proportions of propionate ions and deliquescent material which 
may be included in a stable solution of the invention as indicated in the 
test results presented above. 
Method for Producing the Invention 
The method for producing the product of the invention is believed most 
clearly understandable by a description of the production of specific 
batch weights of the product with the ingredients in relative proportions 
that will produce a satisfactory embodiment of the product. 
EXAMPLE 1 
The total batch weight for the first example given is 300 lbs., and the 
product to be produced is an aqueous solution of sodium propionate in 
which the humectant is glycerine, and which includes MSG. In this example, 
the MSG will be made during the process by including hydrochloric acid and 
glutamic acid among the ingredients. 
For this 300 lb. batch, the ingredients and amounts thereof by weight are 
as follows: 
26.5 lbs. water 
3.3 lbs. "concentrated" hydrochloric acid [HCl] 
3.6 lbs. 100% glutamic acid HOOC(CH.sub.2).sub.2 CH(NH.sub.2)COOH 
7.25 lbs. 100% glycerine 
3.0 lbs. deliquescent material consisting of 1.5 lbs. magnesium chloride, 
1.0 lb. calcium chloride, 0.3 lb. manganese chloride, 0.1 lb. ferric 
chloride, and 0.1 lb. zinc chloride 
110.0 lbs. 50% sodium hydroxide [NaOH] 
146.35 lbs. 100% propionic acid CH.sub.3 CH.sub.2 COOH 
The hydrochloric acid and glutamic acid are added to the water before the 
water is added to another of the ingredients except possibly the 
glycerine, and this will produce glutamic acid monohydrochloride, as 
follows: 
ti C.sub.5 H.sub.9 O.sub.4 N+HCl.fwdarw.C.sub.5 H.sub.10 O.sub.4 N.sup.+ 
Cl.sup.- 
The glycerine is added to the water, preferably after the hydrochloric acid 
and glutamic acid have been added; but if desired, the glycerine may be 
added to the water before the hydrochloric acid and glutamic acid. 
The deliquescent material is added to the water, preferably after the 
hydrochloric acid and glutamic acid have been added; but if desired, the 
deliquescent material may be added to the water before the hydrochloric 
acid and glutamic acid. 
Then, preferably the next step is to dilute the propionic acid with the 
water which already contains the glutamic acid monohydrochloride and the 
glycerine and deliquescent material, and then the sodium hydroxide is 
added to the mixture. Alternatively, the sodium hydroxide may be diluted 
wtih the water which contains the glutamic acid monohydrochloride, and 
then the propionic acid added to this mixture. The first of these two 
alternatives is preferred, because when the water is added to the sodium 
hydroxide, a large amount of heat is generated, and by having the large 
quantity of propionic acid already present when the sodium hydroxide is 
added, the propionic acid will serve as a heat sink and the thermal 
activity will be reduced. 
The chemical reaction of the propionic acid with the sodium hydroxide is as 
follows: 
EQU Propionic Acid+Sodium Hydroxide.fwdarw.Sodium Propionate+Water 
or 
EQU CH.sub.3 CH.sub.2 COOH+NaOH.fwdarw.CH.sub.3 CH.sub.2 COO.sup.- Na.sup.+ 
+H.sub.2 O 
In preparing a sodium propionate solution with high propionate ion 
concentration as is desirable for the present invention, applicant has 
found that when sodium hydroxide is added directly to propionic acid there 
is a serious precipitation problem. However, by placing all of the other 
ingredients, including the water, glycerine, hydrochloric acid and 
glutamic acid, in one of the solutions before the sodium hydroxide and 
propionic acid are brought together, the number of molecules per unit of 
space has already been diluted out sufficiently to produce a solution 
after completion of the acid/base reaction with all of the ingredients 
fully dissolved and with a high propionate ion concentration and long-term 
stability suitable for the purposes of the present invention. 
During the reaction, the hydrochloric acid component of the glutamic acid 
monohydrochloride will be neutralized by the sodium hydroxide and thereby 
removed from the glutamic acid, and the glutamic acid will react with the 
sodium hydroxide to produce MSG, as follows: 
EQU Glutamic Acid+Sodium Hydroxide.fwdarw.Monosodium Glutamate+Water 
or 
EQU C.sub.5 H.sub.9 O.sub.4 N+NaOH.fwdarw.C.sub.5 H.sub.8 O.sub.4 N.sup.- 
Na.sup.+ +H.sub.2 O 
For this 300 lbs. batch example, there is 48.4 percent propionic acid by 
weight, of which 98.65 percent by weight is propionate ion. Thus, in the 
product of the invention that is produced in this example, there is 48.14 
percent by weight of propionate ion. 
If the MSG is to be added as MSG instead of being formed during the process 
by getting it into solution with hydrochloric acid and reacting it with 
sodium hydroxide, then the MSG is preferably added to the water before the 
water is combined with the other ingredients of the product. For the 
foregoing 300 lbs. batch, the 3.6 lbs. of glutamic acid used in the 
formulation will result in 4.14 lbs. of MSG in the final product. 
Accordingly, if the MSG is not made during the process but added at the 
end of the formulating procedure, 4.14 lbs. of MSG will be added to make 
the 300 lb. batch formulation in this example. In that case, without the 
presence of hydrochloric acid as one of the ingredients, in order to 
neutralize the product, 3.7 lbs. less of sodium hydroxide will be used, 
and then to make up the same batch weight and relative amounts of the 
ingredients in the batch, water will be added in the amount of 3.7 lbs. 
Such water is preferably added prior to the mixing together of the sodium 
hydroxide and propionic acid in accordance with the procedure referred to 
above of diluting out the number of molecules per unit of space as much as 
possible to work against precipitation. 
In the final product, the sodium propionate ionizes in the solution to 
become: 
EQU CH.sub.3 CH.sub.2 COO.sup.- NA.sup.+ 
It is this propionate ion which is the effective mold inhibitor in the 
product, and it inhibits mold in the same way and with the same efficacy 
as the corresponding propionate ion does in propionic acid, but without 
the offensive odor and corrosiveness of the propionic acid. 
It is to be understood that in the preparation of this first example as 
described above, the ingredients are to be mixed as required at the 
various stages. 
The percentages by weight of active ingredients in this first example are 
approximately 48.14 percent propionate ion, 1.0 percent deliquescent 
material, 2.42 percent humectant, and 1.38 percent MSG, and this first 
example product has a pH of approximately 6.6. 
EXAMPLE 2 
Applicant has prepared a 100 lb. batch of the product of the invention. The 
ingredients for this batch were: 
10.8 lbs. water 
1.3 lbs. 100% MSG 
2.3 lbs. 100% glycerin 
1.0 lb. deliquescent material, consisting of approximately 0.5 lb. 
magnesium chloride, 0.33 lb. calcium chloride, 0.1 lb. magnesium chloride, 
0.033 lb. ferric chloride, and 0.033 lb. zinc chloride 
36.4 lbs. 50% sodium hydroxide 
48.2 lbs. 100% propionic acid 
First, the MSG was mixed and dissolved in the water. Then the glycerine and 
deliquescent material were added to the water and mixed. Then the sodium 
hydroxide was added to the water/MSG/sodium hydroxide and mixed. Finally, 
the propionic acid was added to the other ingredients and mixed. The 
reaction was then allowed to proceed to completion, resulting in a 
mold-inhibiting product according to the invention having the following 
relative proportions by weight of the ingredients: 
47.55% propionate ion 
1.0 % deliquescent material 
2.3 % humectant 
1.3 % MSG 
It will be noted that some water was added in each of the above two 
examples. In order to provide the solution product of the present 
invention with maximum propionate ion content, water need not be 
deliberately added as in these two examples, because sufficient water for 
a satisfactory aqueous solution will automatically be produced in the 
reaction when the ingredients are mixed, from the 50 percent hydroxide 
component of the mixture, and also because water is a reaction product 
between the acid and the base. The water in the aqueous solution product 
enables the salt of propionic acid in the product to be substantially 
uniformly dispersed when the product is applied to the feed. The water 
also maintains the salt of propionic acid in hydrolyzed condition so that 
the propionate ion component of the solution is enabled to most 
efficiently perform its function as a mold inhibitor. 
In summary, the aqueous solution product of the present invention is the 
first completely satisfactory mold-inhibiting product of which applicant 
is aware, the product having no objectionable odor or corrosion 
characteristics, so that the product is comfortable to use and should be 
acceptable on a worldwide basis. The product of the invention has been 
found experimentally to be fully acceptable and will not contaminate 
workers with any objectionable odor. In addition to its excellent 
mold-inhibiting characteristics, the product of the invention also has 
surprising and synergistic dust-inhibiting characteristics which solve 
heretofore very serious dust problems in connection with poultry litter. 
It is to be understood that although the present invention has been 
described hereinabove primarily for use in connection with poultry litter 
mold and dust problems, the invention is fully applicable to a variety of 
other mold and dust problems. Accordingly, the invention is not intended 
to be limited to use in connection with the specific examples described 
herein. 
While the present invention has been described herein in what are conceived 
to be the most practical and preferred embodiments, it is recognized that 
departures may be made therefrom within the scope of the invention, which 
is therefore not to be limited to the details disclosed herein, but is to 
be accorded the full scope of the appended claims.