JPS59189811A - Vacuum frying apparatus - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a vacuum frying apparatus. Several types of vacuum frying devices have already been devised. For example, the drawings are disclosed in Japanese Patent Publication No. 47-665, Japanese Patent Publication No. 52-28865, Japanese Patent Publication No. 58-17666, Japanese Patent Application Laid-Open No. 57-22652, etc.

Generally, a vacuum frying apparatus is composed of various parts such as a fryer, a heating means, a vacuum generating means, a condensing means, a stirring means, a transfer means (in the case of a continuous fryer), an oil supply means, and an oil location means.

For example, Japanese Patent Publication No. 57-22652, Japanese Patent Publication No. 52-28
No. 865, Japanese Patent Publication No. 47-665, etc., do not mention any condensation means among these, and there is only a single stage of inclined shell-tube type in Japanese Patent Publication No. 58-1766'6. As can be seen from the fact that the condenser is only shown in the drawing, condensing means have not been studied in depth in the art.

The present inventor has worked to commercialize the vacuum frying method and has spent many years improving the process and equipment.

Of course, when commercializing this method, attention must be paid to (1) quality, (2) rationalization of operations, especially shortening of frying time, and (3) economical use of fats and oils.

Regarding (1), (a) Quality is strongly influenced by the conditions of the water removal process in the latter half of frying, and the so-called bound water (strongly molecularly bound to proteins, polymeric carbohydrates, etc.) that remains in the raw material If you do not thoroughly remove water), you will not be able to obtain a porous and crisp product.

In addition, removal of bound water is more difficult than removal of so-called free water in the first half of frying process, and the quality is partly influenced by the conditions for removing free water in the first half of frying process. In order to obtain a puffed, crisp product with good water rehydration, it is advantageous to rapidly remove free water.

Generally, it is preferable to remove at least 80% or more of the moisture in the raw material within several minutes, or at most 5 minutes, from the start of frying.

Regarding (2), as mentioned in (1), it takes time to remove the so-called bound water (normally, it involves a quiet collision phenomenon compared to the process of free water, which involves rapid collisions). (The process of removing bound water can be estimated to be about 1.5 to 2.5 times as long.) It is necessary to complete the latter process as quickly as possible.

Regarding (3), intense shaking occurs in the first half of the frying process, and a portion of the fat and oil is carried away to the condensing section due to the steam distillation phenomenon or the concomitant phenomenon of fat and oil splashes accompanying the rapid discharge of water vapor. The loss of fats and oils reaches 5% in some cases, and usually several percent.

We have experienced that problems such as these occur with scale-up.

Although these are not clearly recognized on an experimental scale (several hundred grams to several hundred grams in terms of raw materials), they are not clearly recognized in operations based on profitability (at least several tens of kilograms or more in terms of raw materials, oil-to-fat ratio of 8% or more).
15%), it becomes extremely noticeable.

For example, if the raw material is about 5 mm thick, it is possible to obtain a crisp product with a moisture content of 3% or less under mild conditions of 100 Torr and 1120 to 180°C.

However, as a result of processing 40 to 90 kg ffi of bananas, pineapple, pine mushrooms, etc. under the conditions of 40 to 100 TOrr and 1100 to 120°C, which have traditionally been the standard conditions for this method, the inventor found that a 30 minute long Even if it took a long time, it was not possible to obtain a crispy puffed product. In this case, in order to increase the efficiency per batch, the fat-to-oil ratio must be at least 8% to 15%, and the above results were obtained under this restriction.

On the other hand, the inventor has determined that the pressure of the fryer is lower than 20 Torr in the latter half of the frying process, preferably l Q T
orr or less, the scale can easily dry to a moisture content of 3% or less in a short time even under the above operating conditions.
The invention has been completed.

However, the degree of vacuum is reduced to 2 in the pre-frying process.
It is practically impossible and futile to maintain it below 0 Torr. The water vapor and gas that are explosively generated during the first half of the frying process are removed and condensed to 20 Torr.
If you try to keep it below, you probably have an extraordinary ability,
Expensive equipment would be required.

In fact, free water can be removed smoothly at 150 Torr or less, so there is no need to require more capacity than necessary.

Ideally, the exhaust means and condensation means should be switched between the first half and the second half of the frying process.

This is because in the first half, a high degree of vacuum is required, the pumping speed is greater than the ability to reach it, the exhaust means is insensitive to water suction, such as a steam ejector, and the condensing system is capable of condensing a large amount of water vapor at once. In contrast, in the second half, the pumping speed may be low, but pumping means with a high degree of vacuum attainment ability, such as a vacuum pump with a mechanical booster or a diffusion pump, and a small volume pump with low water vapor pressure are required. This is because it is necessary to employ a condensation system that reliably condenses water vapor.

However, in practice, it is preferable to share one means in terms of equipment investment and layout. Particularly in the case of a batch-type system, it is difficult to make a profit unless the one-patch operation time is set short and the number of staff is reduced, so complicated operations must be omitted as much as possible.

In order to practically solve these two conflicting demands, the inventor found that it would be sufficient to adopt a multi-stage series capacitor, and completed the present invention.

According to the present invention, the entire public money frying process can be completed using only one commercially available, inexpensive piston-type or rotary-type vacuum pump.

The configuration of the present invention is as follows.

(1) The exhaust gas is first led to the first condenser.

This method can be of any type, such as a tube type or a plate type, but the temperature of the steam is sufficiently lowered here, and at least a portion of the steam and a portion of the oil and fat are cooled to the extent that they are condensed. . Generally, room temperature water or well water may be used, and in some cases (if the heat exchange area is small) cooled water (0 to 5°C) may be used. As a result, the vapor pressure decreases rapidly, and the rate can be reduced by a sufficient amount. Therefore, the cooling capacity of the condenser after the second phase is small, and water is sucked into the pot due to turbulence,
Can prevent condenser distortion.

For example, as in Japanese Patent Publication No. 53-17666, - group,
When only a condenser with a long cooling pipe is used, a large amount of water vapor that rapidly flows in (during the first few minutes of the frying process) quickly turns into water at the rear end.
Due to the pulsating motion of water and the accompanying turbulence and pulsation of water vapor, stable bumping within the fryer cannot be maintained, and bumps may occur in some cases. If the velocity of water vapor is too high, the efficiency of transfer of large latent heat due to the gas-liquid phase conversion will be poor, and the overall heat exchange efficiency will be reduced.

The second condenser is also of any type, but its cooling is at least 10°C or lower, preferably with cooling water of 0 to 5°C.
This is carried out using a refrigerant (for example, brine) at a temperature of about 0°C to -5°C. Its cooling capacity shall be sufficient to condense almost all of the water vapor and oil. However, when using brine, etc., partial freezing must not occur.

Freezing disrupts the progress of continuous operations. 2nd conotine 1. Water vapor that could not be captured by the sensor (although it is a small amount)
is condensed by providing a third condenser as required. This is effective when maintaining the inside of the fryer at several Torr or less in the latter half of the frying process. When removing ice with brine, the exhaust diameter can be sufficiently increased to prevent clogging, and the ice can be removed by hot air ventilation, hot water injection, etc. in the first half of the frying process, isolated from the decompression system.

The temperature of the first and second condensed water (generated in the first half of the frying process) is set to a level that does not coagulate the fats and oils contained therein. (This can be done by adjusting the flow rate of cooling water.) In the vacuum frying method, the finish and shelf life of the product (AV, POV)
Solid fats (coconut oil, coconut oil, palm oil, etc.) are preferred over solid fats (coconut oil, coconut oil, palm oil, etc.), but in these cases, the temperature of the condensed water that is produced in large quantities in the first half should be kept below 30°C. No.

Furthermore, in order to reduce the amount of oil flying, it is effective to provide a baffle plate in front of the exhaust hole of the fryer that is larger in diameter than the hole.

The generated condensed water is led to a container with liquid-liquid separation ability (usually a cylindrical container with a conical bottom), isolated from the depressurization system by means such as a cock, and the upper intake valve is opened to drain the lower end. If the structure is such that the cock can be opened, water and oil can be efficiently collected at any stage during frying.

This container may be attached to the bottom of each connotesser, or may be provided to collectively contain several condensed waters.

In practice, approximately 90% or more of the condensed water is recovered within 5 minutes. Moreover, the temperature of this condensed water is quite high, so
There is a risk that it will evaporate again under high vacuum conditions in the latter half of frying, interfering with drying of the fries. Therefore, it is preferable to isolate the condensed water from the vacuum system at the end of the first half.

Since the water condensed in the latter half is small and contains little oil, it can be strongly cooled and kept in the free space at the bottom of the condenser, or it can be led to another container. These can simply be removed together with the condensed water that forms during the first half of the next frying operation.

EXAMPLES The present invention will be specifically described below with reference to Examples, but the scope of the present invention is not limited to these.

4. Example In a batch type fryer with an oil amount of 450 kg, slices (
a In1n ~4 mm thick) banana 35 hg
Store it in a basket and hang it in a 2-3 cm layer.

Immerse at an oil temperature of 120°C and 60 Torr. The heat transfer area of the fryer is maintained at 80°C to 90°C with 5nf and maximum 6 kg/cd of steam 200#/b. The exhaust means is operated at an exhaust rate of 316 m3/min, and the degree of pressure reduction is controlled by adjusting the leak valve. The first condenser is a tube type (cooling water flows through the tube) with a heat transfer area of 1517/cm and a maximum of 400 g of cooling water at approximately 20°C.
/min, water can be passed through. The second container is a shell tube type (exhaust gas passes through the tube), has a heat transfer area of 1.0 mm, and passes 5°C cooling water at a maximum rate of 60 rpm. Cooling water is chiller unit (5QQQkcal/11r
) powered by The third condenser is a tube type (cooling water flows through the tube) with a heat transfer area of 0.5
Cooling water of 4Qkg/min at 5°C is passed through.

A violent bump occurs about 1 minute after soaking.

Maintain a reduced pressure of IQQTorr and an oil temperature of 90°C. The steam temperature in the second condenser is maintained at 40-50°C. After 5 minutes, the bump quickly subsided and the degree of vacuum was 70T.
It recovers to orr. Close the cocks of the condensate water reservoirs (also serving as liquid-liquid separators) from the first and second condensers,
Frying is completed in 13 minutes while maintaining the oil temperature at 5 to 7 Torr and 100°C.

Collect approximately 1# of fats and oils.

Procedural amendment (formality) %formula% 1.Display of the incident 1981 Patent Application No. 62609 2. Name of the invention 3 Person who makes corrections Relationship to the case Patent applicant 5. Subject of amendment: application/specification

Claims (4)

[Claims] (1) Steam generated during vacuum frying is led to at least two or more condensers connected in series, and the first condenser condenses at least part of the steam and part of the flying fats and oils. In the first half of vacuum frying, the degree of vacuum in the fryer is reduced to 20 to 150 Torr.
A vacuum frying device characterized by having the ability to maintain the temperature at 20 Torr or less in the second half. (2) The vacuum frying apparatus according to claim (1), characterized in that a liquid-liquid separator is connected to at least one condenser. (3) Claim (2) characterized in that the liquid-liquid separator can be airtightly separated from the depressurized space of the fryer by a cock, valve, etc., and the condensed fluid inside can be taken out at any time.
vacuum frying equipment. (4) The vacuum frying apparatus according to claims (1), (2), and (3), characterized in that a baffle plate larger than the inner diameter of the exhaust pipe is provided in front of the exhaust pipe of the fryer.