Device for treating nuts

Disclosed is a novel method of treating nuts with a compressed carbon dioxide gas so as to make them oxidation-resistant. For carrying out the method, a device is used, which can contain a compressed carbon dioxide gas and which is equipped with (i) (a) door(s) or (a) gate(s) to put nuts into and take them out of itself, (ii) (a) heater(s) to heat nuts in itself, (iii) (a) chiller(s) to chill nuts in itself, and (iv) (a) valve(s) to introduce a carbon dioxide gas into itself and release the gas out of itself. Nuts as treated by the novel method with the illustrated device are to be satisfactorily oxidation-resistant when they are stored.

FIELD OF THE INVENTION 
This invention can be utilized for treatment of nuts, especially of high 
fat content. Nuts generally contain a lot of fats and are quite easily 
oxidized after heating or roasting so as to lose their commercial values. 
BACKGROUND OF THE INVENTION 
General methods to retard or prevent oxidation of foods include addition of 
antioxidant or a substitution of air in pouches with inactive gases, for 
instance nitrogen or carbon dioxide, or addition of oxygen absorbing 
agents into pouches. As for nuts, an addition of antioxidants is not very 
effective. And a substitution of air with an inactive gas or addition of 
oxygen absorbing agents in pouches is very costly, because more precious 
pouch material is required to cut off an invasion of oxygen through pouch 
films, and these methods lose their effect after opening the pouches. It 
has never been previously known to treat nuts with compressed carbon 
dioxide gas to retard their oxidation, so this is a novel method of 
antioxidation and devices of this invention are also novel. 
SUMMARY OF THE INVENTION 
The present invention provides a novel method of treating nuts with a 
compressed carbon dioxide gas so as to make them oxidation-resistant. 
As one embodiment of carrying out the novel method, there is provided in 
accordance with the present invention a device which can contain a 
compressed carbon dioxide gas and which is equipped with (i) (a) door(s) 
or (a) gate(s) to put nuts into and take them out (ii) (a) heater(s) to 
heat nuts within the device, (iii) (a) chiller(s) to chill nuts in the 
device, and (iv) (a) valve(s) to introduce carbon dioxide gas into the 
device and release the gas therefrom.

DETAILED DESCRIPTION OF THE INVENTION 
The word "NUTS" in this invention includes peanut, almond, pecan nut, seed 
of pumpkin, walnut, sesame, sunflower seed, hazel nut, brazil nut, 
pistachio nut, cashew nut, macadamia nut, seed of pine tree, seed of rotus 
and so on. 
Fats contained in nuts are composed of highly unsaturated fats, so they are 
rapidly oxidized after roasting or heating or frying. However coffee beans 
are relatively stable after roasting though they contain 
oxidation-sensitive aroma components. The reason for roasted coffee bean 
stability is ascribed to carbon dioxide gas which evolves during roasting 
owing to chemical reactions, and carbon dioxide gas remains after roasting 
in coffee beans. When hot water is poured onto ground roasted coffee 
beans, many bubbles evolve, which are composed chiefly of carbon dioxide 
gas. And also it is said that roasted coffee beans which do not release 
bubbles at the time of extraction by hot water lose their aromas. 
So it is probable that when carbon dioxide gas is pushed into nuts 
forcedly, it can prevent or retard oxidation of oils in the nuts. The 
inventors made some experiments to treat nuts with compressed carbon 
dioxide gas and found that in some cases oxidation velocities became much 
slower than untreated nuts. And the fact that nitrogen gas cannot replace 
carbon dioxide gas was also found out, too. 
The methods of this invention involves treatment of nuts with compressed 
carbon dioxide gas under heating conditions. Carbon dioxide gas of 
pressure below 30 Kg/cm.sup.2 is effective enough. If higher pressure is 
chosen, a discharge of compressed gas after treatment requires more time, 
because rapidly discharging gas causes breakage of nuts owing to a violent 
vaporization of carbon dioxide dissolved into nuts tissues. 
Temperature higher than room temperature but not too high to cause browning 
or roasting should be chosen to enhance carbon dioxide gas diffusion into 
nuts. It is also desirable to chill nuts quickly after carbon dioxide gas 
treatment to prevent damage from excess heating or browning and a loss of 
carbon dioxide gas from nuts. And also it is recommended to evacuate air 
from the treatment vessel before carbon dioxide gas treatment to remove 
oxygen completely. 
A device of this invention is composed of the following features. 
(1) Its main part is a vessel which can hold compressed carbon dioxide gas 
therewith. 
(2) It has to have (a) door(s) or (a) gate(s) to put nuts into and take 
them out. Of course these doors or gates should be airtight and withstand 
the pressure of the compressed gas. 
(3) The device has (a) heater(s) to heat nuts during treatment. These 
heaters can be composed of heat exchangers, e.g. pipe(s) or tube(s) or 
plate(s) or jacket(s) through which steam or hot water or hot oil or any 
other hot fluid can circulate, or electrical heater, or generators of 
radiation, such as infrared or microwave, can be provided. 
(4) It has (a) chiller(s) to chill nuts therewithin quickly after 
treatment. These chillers can be made in the same manner as the heater 
through which chilled water or chilled oil or any other chilled fluid can 
circulate. In some cases heaters can be used also as chillers, when hot 
fluid is replaced by chilled fluid. 
(5) It has (a) valve(s) through which compressed carbon dioxide gas is 
supplied into and discharged out of the vessel. In some cases a single 
valve can be used for introduction as well as release of the CO.sub.2 gas. 
(6) It is desirable to make a device in such a manner so that it can be 
rotated freely to make (a) door(s) or (a) gate(s) face upward or downward. 
In this case nuts are put into the device through (a) door(s) or (a) 
gate(s) when the door(s) or gate(s) are facing upwardly, and after 
treatment the device is rotated upside down and nuts are easily taken out 
when it (they) is (are) facing downwardly. 
(7) It is also preferable to attach (a) vibrator(s) on or in a device to 
facilitate taking treated nuts out of the device. 
(8) To save carbon dioxide it is also recommended to attach (a) 
compressor(s) and (a) container(s) or (a) bomb(s) to recover and store 
used carbon dioxide gas. 
(9) To discharge air and remove oxygen completely out of a device, it is 
also preferred to attach (a) pump(s) to a device. 
A typical structure of device of this invention is shown in FIG. 1. 
A main part of the device, i.e., a vessel 1 can contain compressed carbon 
dioxide gas therewithin. Through a door or a gate 2 nuts are put into and 
taken out of the vessel 1. In this figure the door or gate 2 is placed 
downward, but when the vessel is rotated upside down, it faces upwardly. 
The vessel 1 can be rotated freely by a shaft 6 which is rotated by a 
motor 5. When the door or the gate 2 is upward, nuts are easily put into 
the vessel 1 and when downward, they are easily taken out of the vessel 1. 
Heaters 3 are provided in the vessel 1, which can be made as hollow plates 
or tubes or pipes to circulate hot fluid inside. And in this case heaters 
3 are easily changed into chillers if chilled fluid is passed inside 
instead of hot fluid. A vibrator 7 is attached to make it easy to take 
treated nuts out of the vessel 1. Preferably a pressure gauge 8, a 
thermometer 9 and a window 10 are attached to the vessel 1 to confirm a 
process condition in the vessel 1. Carbon dioxide gas is supplied from a 
bomb 13 through valves 16e and 16a into the vessel 1. A pipe 4 is through 
the shaft 6b and is connected to a distributing pipe by means of a sealer 
15 to enable the vessel 1 to be rotated. Before supplying gas into the 
vessel 1, a pump 14 evacuates air from the vessel 1. After a treatment is 
finished, gas is discharged out of the vessel 1 through the pipe 4 by 
means of a compressor 11. At that time compressed gas is chilled by a 
chiller 12, then stored in the bomb 13. 
EXAMPLE 1 
Commercial roasted peanuts 350 gr were put into a glass container which was 
placed onto the other same one without peanuts in an autoclave of 3L inner 
volume. 
After sealing the autoclave, carbon dioxide gas was supplied from a bomb 
until the inner pressure became 10 Kg/cm.sup.2, then released rapidly to 
an atmospheric pressure. This procedure was repeated two more times to 
replace air for carbon dioxide gas in the bomb. 
Then carbon dioxide gas was filled in the bomb to a pressure 10 Kg/cm.sup.2 
and the autoclave was heated to maintain the temperature of peanuts 
between 70.degree..about.72.degree. C. for an hour, then carbon dioxide 
gas was discharged for about 30 minutes, while the autoclave was placed at 
a room temperature, then the autoclave was opened to take peanuts out. 
These peanuts are called (A). 
The same commercial roasted peanuts treated in the same manner under the 
condition that the chilling the autoclave as well as discharging gas was 
done for 18 hours at a room temperature. 
These peanuts are called (B). 
Peanuts not treated are called (C). 
(A), (B) and (C) were put in pouches which are made of polyethylene 80 
.mu.m thick and sealed with rubber bands. They were stored at a room 
temperature and periodically about 50 g of them were extracted with fresh 
ethyl ether of a chemical reagent grade to extract oils in Soxlet 
extractor. Extracted oils were condensed and dried completely in vacuo, 
then titrated to evaluate their acid values (AV: mg/gr) and peroxide 
values (POV: meq/1000 gr). 
The result is cited in the following table. 
______________________________________ 
JUST AFTER 
THE AFTER 1 AFTER 2 
TREATMENT MONTH MONTH 
______________________________________ 
(A) AV 1.36 1.11 1.01 
POV 3.8 26.81 35.41 
(B) AV 1.25 1.13 0.94 
POV 2.6 24.81 34.11 
(C) AV 1.38 1.08 1.64 
POV 4.7 33.71 42.01 
______________________________________ 
EXAMPLE 2 
Roasted peanuts freshly roasted in a factory were treated with carbon 
dioxide gas in a similar manner described in Example 1. In this experiment 
they were treated under the condition of a pressure 25 Kg/cm.sup.2 and a 
temperature 120.degree..+-.5.degree. C. for an hour. After the treatment 
the autoclave was chilled forcedly by putting wet towels on its surface 
for about 2 hours till the inner temperature became 50.degree. C., then 
carbon dioxide gas was released for about 15 minutes. 
They were pouched in the same manner described in Example 1, then stored at 
37.degree. C. 
______________________________________ 
JUST AFTER THE 
TREATMENT AFTER 1 MONTH 
______________________________________ 
TREATED AV 0.92 0.93 
POV 1.5 17.8 
UNTREATED AV 1.14 0.97 
POV 12.1 51.8 
______________________________________ 
AFTER 2 AFTER 3 AFTER 4 
MONTHS MONTHS MONTHS 
______________________________________ 
TREATED AV 1.05 0.93 1.19 
POV 38.3 37.4 40.8 
UNTREATED AV 1.17 1.17 1.21 
POV 80.4 62.7 64.9 
______________________________________ 
EXAMPLE 3 
Commercial roasted peanuts were treated in a similar manner described in 
Example 1 under the condition of a pressure 5 Kg/cm.sup.2 and a 
temperature 80.degree. C. for an hour and the release of carbon dioxide 
gas was done for 30 min. without forced chilling at a room temperature. 
They were pouched in the same manner described in Example 1 and stored at 
37.degree. C. 
______________________________________ 
JUST AFTER 
THE AFTER 1 AFTER 2 
TREATMENT MONTH MONTH 
______________________________________ 
TREATED AV 1.45 1.11 2.32 
POV 21.6 69.1 89.3 
UNTREATED AV 1.78 2.23 2.37 
POV 64.7 113.2 129.4 
______________________________________ 
EXAMPLE 4 
Roasted peanuts freshly roasted in a factory were treated with compressed 
nitrogen gas under the condition of a pressure 25 kg/cm.sup.2 and of a 
temperature 120.degree..+-.5.degree. C. Before the treatment, air in the 
autoclave was replaced by nitrogen in the same manner described in Example 
1. After the treatment, chilling the autoclave forcedly and releasing 
inner gas were done in the same manner described in Example 2. Peanuts 
were packed in the same manner described in Example 1 and stored at 
37.degree. C. 
______________________________________ 
JUST AFTER THE 
TREATMENT AFTER 1 MONTH 
______________________________________ 
TREATED AV 0.88 0.69 
POV 1.0 34.0 
UNTREATED AV 0.90 0.90 
POV 1.1 35.4 
______________________________________ 
In this experiment no effect is found.