Method for the preservation of wheat and device useful therefore

A humidity measuring device and standard is disclosed. Humidity is measured by comparing the reflectivity and selected wavelengths of light of a grain sample to the reflectivity of a standard of known humidity in order to ascertain humidity. A holographically generated reflecting standard with a sculptured wavelength and amplitude filtering element is utilized.

TECHNICAL FIELD 
The present invention relates to an improved method for measuring the 
moisture content of wheat whereby the same may be regulated to optimize 
maintenance of the nutritional value of the grain. 
BACKGROUND 
Long before the dawn of recorded history, man has cultivated various plants 
for the nutritional value of their fruits and grains. The majority of 
important food plants today have originated from three principle regions 
of the world, namely, the fertile crescents in the Middle East, the 
southern Chang Jian River valley and Yunnan Province in China, and the 
relatively arid areas in the foothills of the Andres Mountains in Peru. 
These areas, while separated by great geographic distances, share one 
important characteristic, which, in the evolutionary history of plant life 
on earth, have caused the plants of those areas to develop fruits with 
relatively large volumes of highly nutritional substances. 
In particular, relatively long arid periods in each area cause native 
plants to evolve survival strategies centering around highly efficient 
systems for the storage of moisture and nutrition to sustain the 
development of new plants. Specifically, these systems took the form of 
large seeds (such as wheat), fruits (such as tomatoes), tubers (such as 
potatoes) and bulbous root systems (such as onions). Even today, 
agricultural scientists concentrate their efforts for gathering new 
genetic breeding materials on these areas of the earth due to the great 
variety of plants available, only a tiny fraction of which have been 
commercially developed. 
Just about as soon as human populations began the cultivation of food 
plants, storage and preservation of the same became a primary problem for 
solution. Food products that cam e from the grasses offered especially 
promising opportunities in this regard. To those early farmers, grains 
such as barley, rye, alba and corn must have seemed to have almost 
unlimited useful shelf life. Thus, Aztec corn and Greek alba both found 
their way into granaries which were invented in similar fashion on both 
sides of the Atlantic Ocean. Generally, these storage facilities, which 
remain unchanged in their essentials since ancient times, are large closed 
spaces which protect the grain from the adverse environment effects of 
rain and sun. While the ancients could hardly have suspected the effects 
of long term exposure to ultra-violet radiation on nutritive value, the 
more obvious connection between excess moisture and rot suggested keeping 
grain in closed receptacles, a solution which simultaneously addressed 
many of the problems associated with other aspects of the deterioration of 
grains, including ultra-violet deterioration. 
One of the most important events in the agricultural history of western man 
was the discovery, probably in a field of alba, of a particular plant 
which would come to be known as wheat. An incidental but most important 
characteristic of this plant was the fact that when a number of grains 
were rubbed against each other, the coarse shell of the seed, also known 
as the chaff, would fracture and become disassociated from the kernel. 
This mutation eventually came to supplant alba almost in its entirety. 
As man's use of wheat continued to grow, he came to learn about the 
preservation of the wheat and the pernicious effects of moisture and 
dryness. In particular, if wheat was allowed to become too moist, it 
rotted. On the other hand, if wheat become too dry, it lost flavor and, as 
learned relatively recently, it also lost nutritional value. Thus, it has 
long been an object in wheat storage to maintain the maximum possible 
moisture without encouraging fungal degradation of the grain. 
It also came to be learned that the best way of judging the moisture 
content of the wheat is by the color of the grain. Thus a skilled granger 
periodically checks wheat from various parts of the granary and observes 
the color thereof from which he can judge the moisture content of the 
grain. In recent years, higher moisture contents can be maintained by, for 
example, fumigation of the grain with anti-fungal agents. In addition, 
while economically impractical, grain moisture content can be maintained 
at a high level by refrigeration of the grain. 
More recently, less precise methods of visual observation of grain color 
have been replace by the measurement of grain color using optical 
instrumentation. Such instruments as spectrum analyzers compare light from 
a standard sample of grain of known humidity which is hermetically housed 
behind a sodium chloride window. Light reflected by an unknown sample is 
analyzed and the spectral content of the reflected light is compared to 
the reflected by standards of known humidity to find a match, thus 
indicating that the unknown has the same humidity as the known matched 
standard sample. 
Unfortunately, such standard samples are very expensive to manufacture and 
have extremely limited life. Accordingly, they must be constantly replaced 
at great cost. The present invention has the object of dispensing with 
this difficulty. 
SUMMARY OF THE INVENTION 
In accordance with the present invention, the controlled humidity sample 
grain standard of the prior art is replaced with a sculpture controlled 
dyeless optical filtration device which may be directly substituted for 
known humidity grain standards in black body integrating sphere 
spectroanalysis systems of the type presently being used in the field. 
Because of the dyeless and inorganic nature of the standard, individual 
inventive standards have indefinite durability. Replication of standards 
is considerably less expensive than in the case of existing real grain 
standards. Moreover, accuracy is far easier to control and improved 
results may be obtained.

BEST MODE FOR CARRYING OUT THE INVENTION 
Referring to FIG. 1, a humidity standard 10 constructed in accordance with 
the present invention is illustrated. Standard 10 generally comprises a 
housing 12 having an input light port 14, a diffracting surface 16 and a 
plurality of output ports 18 and 20. 
The principle of operation is that an incoming wide band infrared beam 22 
containing different wavelengths of light 24 passes through input 14 
striking the surface of diffractor 16. This causes the light to break down 
into component light beams of different wavelengths such as beams 26, 28, 
and 30. In practice, most sources would give a large number of wavelengths 
and only three wavelengths are illustrated in the drawing for simplicity 
of illustration. The effect of the sculptural shape of housing 12 and the 
position of outlet ports or slits 18 and 20 is to pass output beams 26 and 
28 while causing the blocking of output beam 10. Thus analysis is limited 
to particular wavelengths of interest. 
It is noted that both the inside surface 32 and the outside surface 34 are 
coated black. This blocks wavelengths of light such as those of beam 30, 
which are absorbed by the black inside surface 32. Likewise, stray 
radiation will be absorbed by the black coating on the outside surface 34 
of housing 12. Of course, the blackening of the outside surface 34 is far 
less critical than the blackening of inside surface 32 and if a high 
degree of accuracy is not required may even be dispensed with. 
It is contemplated that diffractor 16 will be a diffraction grating 
preferably having focusing characteristics. Accordingly, while the ruling 
of such a grating is possible using a mechanical ruling engine (for 
example, one may rule a conventional Rowland grating and place exit slits 
18 and 20 along the appropriate Rowland Circle), it is contemplated that 
the subject grating would be replicated from a holographic master. 
Such holographic masters, like their mechanically ruled counterparts, are 
easily replicated by impressing a replica of the master grating into a 
cellulose acetate butyrate blank or other known techniques. Replicated 
grating grooves would then be over-coated with gold for high reflectivity 
in the infrared region as well as a high degree of environmental 
stability. 
As alluded to above, it is contemplated that the use of holographically 
fabricated gratings would be preferable to using mechanically ruled 
devices. In particular, holographically generated gratings, such as 
grating 216, in FIG. 2 which may have a plurality of grating structures 
(not evident in a sectional view), have the advantage of providing a 
self-focusing function without the addition of the optical elements such 
as mirrors and lenses and, for example, may even provide a spectrum which 
is planar in configuration. Obviously, this allows for easy fabrication of 
a housing 212 to include a planar sculptured filtering surface 236 
incorporating an inlet slit 214 and outlet slits 238, 240 and 242 which 
are positioned to pass light beams 244, 246 and 248 of different 
wavelengths. The position of the outlet slits controls the wavelength 
passed and the width of the slit controls the amplitude at that 
wavelength. Such self-focusing diffraction gratings which provide planar 
spectra are available from Instruments SA, Inc. of Edison, N.J. 
As noted above, the position of the slit along the focal plane determines 
the wavelength of the light emitted from the housing. The wavelength 
transition, or precision of tuning in on a particular wavelength to the 
exclusion of adjacent wavelengths, may be determined by the amount of 
displacement of the slit from the focal plane. Therefore slit size and 
placement determines the wavelength, the wavelength transition and the 
amplitude of the light emitted from the housing. 
The holographic grating has another advantage over the mechanically ruled 
gratings in that it is capable of capturing different grating structures. 
Gratings may be superimposed with different axis orientation. In this way 
three grating structures may be superimposed and oriented at 120.degree. 
with respect to each other. 
A housing associated with a triple grating structure would then be 
fashioned with three sets of slits. This allows for the custom 
construction of the desired standard spectrum as shown in FIGS. 3 and 4. 
The triple grating structure system may build a composite spectrum in the 
area of wavelength .lambda..sub.0 in the following manner. The triple 
grating will have three associated focal planes each with a corresponding 
wavelength .lambda..sub.n. One slit of width W is positioned at 
.lambda..sub.0 on one focal plane giving a spectrum as shown in FIG. 3A. A 
second slit is positioned at .lambda..sub.0 but displaced from a second 
focal plane giving the less sharp (hump vs spike) spectrum as shown in 
FIG. 3B. A third slit associated with the remaining focal plane is of a 
small width, positioned at .lambda..sub.0 +x and removed from the focal 
plane giving the spectrum of FIG. 3C. The system as a whole will then 
produce a composite spectrum as in FIG. 3D for the area of .lambda..sub.0, 
showing an asymmetrical area around .lambda..sub.0 with a spike at 
.lambda..sub.0. 
By the use of several slits with each of the three focal planes, composite 
spectrums for the neighborhoods of several different wavelengths will 
combine to give a spectrum such as that in FIG. 4. Through proper 
placement of the slits a spectrum may be constructed conforming to desired 
characteristics. 
A variety of slit shapes, as illustrated in FIG. 5, may also be employed in 
fine tuning the emitted spectrum to more closely resemble the desired 
spectrum. Thus a spectrum may be fixed and available representing 
perishable or ephemeral samples not always available and often quite 
expensive. 
FIG. 6 is a top view of the humidity standard 10 of FIG. 1. Here it may be 
seen that slits 18 and 20 may be of irregular shape in order to allow 
passage of the desired wavelenghts. FIG. 6 contemplates a domed housing. 
Such a shaped housing may require different shaped slits than a 
rectalinear housing, such as the one illustrated in FIG. 2, to produce a 
similar standard spectrum. 
A spectral analysis system 250 with which a humidity standard 210 
constructed in accordance with the present invention may be used, is 
illustrated in FIG. 2. Generally, the analyzer 250 comprises an outer 
housing 252 which contains an inside silvered surface 254 which acts to 
internally reflect and thus integrate exiting light beams 244, 246 and 248 
reflected by grating 216 in response to input broadband infrared light 
beam 222 which is output by broadband IR source 256. The output of the 
integrator is received through port 258 which is coupled to a spectrum 
analyzer 260. The standard for a sample of grain to be analyzed is 
supported on platform 262. 
When it is decided to use the inventive system, a humidity standard 210 
having the light reflective characteristics for certain selected 
wavelengths of light which are identical to the characteristics of a 
sample of grain of known humidity is place on platform 262 and a reading 
taken with spectrum analyzer 260. A sample is then placed on platform 262 
and another reading with the spectrum analyzer 260 is taken. One then 
compares the readings with the standard and the sample and if a match 
occurs, the humidity of the sample of grain is known to be that of the 
standard. If not, another standard is inserted into the machine and the 
reading compared until a standard is found which substantially matches the 
readings obtained with the sample. 
With computer technology the standards may be analyzed and used for 
calibration of the system to allow the humidity of a sample to be 
determined immediately through interpolation. 
Variability of the light source and detector can both contribute to the 
need to periodically recalibrate and standardize the instruments. 
While an illustrative embodiment of the invention has been described, it is 
of course understood that various modifications will be obvious to those 
of ordinary skill in the art. Such changes and modifications are within 
the scope of the invention which is limited and defined only by the 
appended claims.