JPS646757B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) This invention relates to a food preservative and a food preservation method using this preservative. It is a food preservative that can shorten the time required to build up the vapor concentration required for food preparation, and can also be stored for a long time.It is a food preservative that can be stored for a long time, and ethyl alcohol is applied directly to food in the form of liquid and high-concentration vapor. It is an object of the present invention to provide a method for preserving foods that can particularly effectively perform a preservative function even when stored under temperature conditions, and can be effectively preserved regardless of the type of storage container. (Prior art and its problems) Food preservation methods and preservatives are disclosed in the previously disclosed Japanese Patent Application Publication No.
No. 53-44642, etc., the preservation method according to this disclosed invention aims to avoid direct contact of ethyl alcohol with liquid food and to maximize its effectiveness by using ethyl alcohol vapor. However, it has not been able to fully demonstrate its effectiveness in foods that are housed in low-temperature atmospheres where ethyl alcohol vapor is difficult to vaporize or in packages that are difficult to maintain completely airtight. On the other hand, in the preservative according to the previously disclosed invention, a substance on which ethyl alcohol is adsorbed is filled in a bag having ventilation holes through which ethyl alcohol is released in a gaseous state. This occurs only through the pores and the amount of ethyl alcohol adsorbed on the adsorbent is smaller than the saturated oil absorption amount to avoid contact between the liquid alcohol and the food, so the evaporation rate is slow and the vapor necessary for food preservation is slow. Concentration rise time is long,
In particular, it is not suitable for preserving foods that begin to deteriorate within a short period of time after being stored. Furthermore, as a kind of preservative according to the previously disclosed invention, it is disclosed that paper, etc. is impregnated with ethyl alcohol and used without packaging, but this method is difficult to handle because the ethyl alcohol drips from the paper, etc. It was inconvenient, and the rate of evaporation of ethyl alcohol could not be controlled and ethyl alcohol evaporated immediately, making it unsuitable for long-term storage. In addition, as food preservatives using ethyl alcohol vapor, Japanese Patent Publication No. 44312/1986 and Utility Model Publication No. 57
-There is one published in No. 43512. The food preservative described in Japanese Patent Publication No. 57-44312 is a plastic container containing ethyl alcohol and sealed with a cement mortar stopper. It is stored with food with the cement mortar stopper facing down, and is stored in an airtight space. It should be left inside. This technique of Japanese Patent Publication No. 57-44312 also has the following problems. (a) Ethyl alcohol in the plastic container passes through the thick structure of the cement mortar plug, which is difficult to pass through, and leaches onto the surface of the cement mortar plug.
Because ethyl alcohol evaporates from the surface of a small cement mortar plug, the leaching rate of ethyl alcohol is slow and the rate of transpiration is also slow.Especially under low temperature conditions where ethyl alcohol is difficult to evaporate, ethyl alcohol vapor reaches a concentration effective for preservative protection. It takes a long time, and sufficient preservation cannot be achieved in the early stages of storage. (b) Under low temperature conditions, a large amount of water contained in the cement mortar plug freezes before ethyl alcohol can leach into the structure of the cement mortar plug, which is difficult to pass through, and ethyl alcohol enters the structure of the cement mortar plug. Leaching of alcohol is inhibited by frozen water, and ethyl alcohol cannot evaporate smoothly, making preservation difficult under low temperature conditions. (c) Ethyl alcohol in the plastic tissue leaches into the structure of the cement mortar plug and then continuously leaches to the surface of the cement mortar plug and evaporates directly from the surface, so that ethyl alcohol does not reach the surface of the cement mortar plug. If the leaching rate is fast, the continuously leached ethyl alcohol overflows from the surface of the cement mortar stopper with a small saturated impregnated amount and drips down in liquid form, making it inconvenient to handle and potentially contaminating preserved foods. . On the other hand, the food preservative described in Japanese Utility Model Publication No. 57-43512 contains an adsorbent impregnated with ethyl alcohol in a container, and a thread that acts as a capillary is inserted into the adsorbent. It protrudes from the outside of the container and is left in a closed space along with the food to be preserved. However, the food preservative disclosed in Japanese Utility Model Publication No. 57-43512 has the following problems. (a) The ethyl alcohol impregnated in the adsorbent leaches into the thread structure with a small cross-sectional area by capillary action and evaporates from the tip of the thread with a small surface area, so the leaching and transpiration rate of ethyl alcohol is slow;
In particular, under low temperature conditions where ethyl alcohol is difficult to evaporate, it takes a long time for ethyl alcohol vapor to reach an effective concentration for preservation, and sufficient preservation cannot be achieved in the early stages of storage. (b) Of the ethyl alcohol impregnated into the adsorbent, the ethyl alcohol surrounding the yarn leaches into the yarn structure due to the capillary action of the yarn, but the ethyl alcohol that is away from the yarn leaves room for leaching into the yarn. Since there is almost no ethyl alcohol, evaporation of ethyl alcohol is maintained only for a short period of time, and long-term storage is impossible. ``Anti-mildew,'' disclosed in Utility Model Publication No. 59-25841,
The "preservative" is disclosed as "an anti-mold or preservative obtained by filling and sealing ethyl alcohol inside a laminated bag with a moisture-permeable film such as polyethylene as the inner layer and a sheet material such as pulp paper as the outer layer." However, this disclosed technology also had the following drawbacks. (a) Moisture-permeable films such as polyethylene allow ethyl alcohol to pass through in gaseous form, but not in liquid form, and the volatilization of the vapor is poor at first, making it impossible to expect a rising effect when added to food, so it is difficult to use it. Pretreatment to promote volatility, such as heating treatment, is required beforehand. (b) If the remaining amount of alcohol in the filling drops below a certain level, or if food is often stored in low-temperature dry conditions where alcohol evaporates and condenses easily, under these conditions ethyl alcohol is in a liquid state and evaporates. It was not suitable for long-term storage because the speed could not be controlled and it evaporated immediately. (Means for Solving the Problems) This invention was made to solve the above problems, and ethyl alcohol is retained in the structure or surface of a porous adsorbent in an impregnated or adsorbed state, and this ethyl alcohol is retained. The amount is 90 to 200% of the saturated amount of ethyl alcohol impregnated in the porous adsorbent,
This porous adsorbent holding ethyl alcohol is housed inside a bag body, and this bag body consists of a permeable layer and a fibrous leaching and transpiration layer coated on the surface of this permeable layer, and the permeable layer is a non-permeable layer. A food preservative consisting of a liquid-absorbing sheet with permeable holes through which ethyl alcohol passes in liquid form, and a food preservative that is stored in a food package together with the food in close or close contact with the food, in order to preserve the food. By providing a food preservation method using food preservatives, the anti-mold effect is immediately apparent from the start of use without any pretreatment, and after a certain period of time, volatilization is prevented due to the effect of the adsorbent. It is rate-limited and maintains its effect for a long period of time, which solves all of the above problems. (Structure of the Invention) [Food Preservative] In this invention, the adsorbent is a powdery material made of a material capable of adsorbing ethyl alcohol, such as silicon dioxide, aluminum silicate, talc, starch, sugar, cellulose, gelatin, sponge, or sponge. , granules, lumps, plates, and other shapes can be suitably used. In this invention, the amount of ethyl alcohol that is partially or completely impregnated into the adsorbent is 90% to 200% of the saturated amount of ethyl alcohol impregnated into the adsorbent.
%, preferably 90% to 150%. In this invention, all of the adsorbents adsorbed with ethyl alcohol near or above the impregnated saturation amount may be used and housed in a package, but some, for example, half of the adsorbents may have an impregnated saturation amount near or above. Impregnating or adsorbing the above ethyl alcohol,
The remainder may be impregnated with or adsorbed with ethyl alcohol in an amount of about 50 to 70% of the impregnation saturation amount, and these may be mixed and used. In the case of this mixing, it is desirable to arrange an adsorbent with a high impregnation amount near the package. The reason for blending 90 to 200% ethyl alcohol in this way is that ethyl alcohol, which has a food preservative function, is applied to the food using high-concentration steam, and its preservative function is maintained even under low temperature conditions where ethyl alcohol is difficult to evaporate. This is to make the product work effectively, to fill the food packaging container with ethyl alcohol in a short time even at room temperature, and to sufficiently replenish steam even when the container lacks airtightness. In this invention, the non-liquid-absorbing permeable layer constituting the package is preferably made of polyethylene, polypropylene, or other synthetic resin material that ethyl alcohol does not permeate, and has permeable holes formed over almost the entire surface. Furthermore, it is desirable that the size of this permeable hole is from several μ to several 100 μ. The reason why we used a synthetic resin that does not allow ethyl alcohol to permeate as the material for the permeable layer and formed permeable holes on its surface is to allow ethyl alcohol to permeate in predetermined amounts not only in the vapor state but also in the liquid state. The reason why the permeation holes are desirably several microns to several hundred microns in size is to prevent the adsorbent particles housed inside from leaking out, and to allow ethyl alcohol to pass through even in liquid form. In this invention, paper, cloth, or other fibrous materials are used as the leaching and evaporation layer constituting the package, and a film is formed by thermally fusing the surface of the permeable layer. The reason for using a fibrous material as the leaching and transpiration layer is that it can be impregnated with ethyl alcohol in liquid form and leached out in the liquid state, while its large surface area allows ethyl alcohol to be evaporated as a highly concentrated vapor. Furthermore, the reason why the leaching evaporation layer was formed as a coating on the permeation layer was that the ethyl alcohol that permeated through the permeation pores of the permeation layer did not accumulate between the permeation layer and the leaching evaporation layer, and was able to pass through the leaching evaporation layer at a high concentration. This is so that it can be released quickly in the form of steam. In this invention, a package consisting of at least two layers, a permeable layer and a leaching and evaporative layer, is used, but other coatings may be laminated on these two basic layers, particularly on the leaching and evaporating layer. An example of this coating layer is a permeable membrane having permeable holes. [Method for preserving food using a food preservative] In the present invention, a food preservative is stored in a food package together with the food in close or close contact with the food to preserve the food. As the food to be preserved in this invention, any of various processed foods, fresh foods, etc. can be suitably used. In this invention, bringing the food preservative into close contact with the food refers to the state in which the surface of the preservative is in direct contact with the food surface, and "in close contact" refers to the state in which the preservative is brought within a few mm from the surface of the food. state. The reason why food preservatives are brought into close contact with food in this way is that ethyl alcohol, which acts as a food preservative, acts on food in a highly concentrated vapor state, further enhancing the preservative effect, and especially preventing ethyl alcohol from evaporating. This is because even under difficult, low-temperature conditions, high-concentration vapor of ethyl alcohol can be applied directly to food in a short period of time to achieve its preservative function. In addition, in the method of this invention, in some cases, the liquid alcohol in the leaching and transpiration layer of the package may come into direct contact with the food, but the total amount of alcohol normally used is about 1 g, and the amount that passes through in liquid form is about 1 g. The maximum amount is 1g, which is usually around 0.3g, which is an extremely small amount compared to more than 100g for food, and in fact, the rate of diffusion of liquid alcohol into the leaching and transpiration layer is faster than the rate of transfer of liquid alcohol to food. Therefore, the amount of alcohol adsorbed to food is small, and since alcohol itself is an additive that is usually allowed to be added directly to food, food contamination problems do not occur much. In this invention, as the food packaging body, common food packaging bodies such as synthetic resins such as polyethylene, polypropylene, bags or boxes made of paper, etc., and boxes made of wood, metal, etc. are suitably used. (Effects) This invention allows ethyl alcohol to be retained in the structure or surface of the porous adsorbent in an impregnated or adsorbed state,
The amount of ethyl alcohol retained is 90 to 200% of the saturated amount of ethyl alcohol impregnated in the porous adsorbent, and the porous adsorbent holding this ethyl alcohol is housed inside a bag, and this bag is permeable. layer, and a fibrous leaching and evaporation layer coated on the surface of this permeable layer, and the permeable layer has permeable pores in the size of several microns to several hundred microns that allow ethyl alcohol to pass through in liquid form through the non-liquid absorbing sheet. Since it is a food preservative formed by the following effects: The supersaturated ethyl alcohol adsorbed on the surface of the porous adsorbent passes through the permeable pores in liquid form and leaches into the fibrous leaching and transpiration layer, creating a large surface area on the surface of the permeable layer. Since ethyl alcohol evaporates at a high concentration from the leaching transpiration layer, the evaporation rate of ethyl alcohol is fast in the early stage of storage, and even under low temperature conditions where ethyl alcohol is difficult to evaporate, ethyl alcohol vapor can reach an effective concentration for preservatives in a short period of time. This enables effective preservation even in the early stages of storage. After the alcohol held in an adsorbed state on the surface of the porous adsorbent evaporates, the ethyl alcohol held in the impregnated state within the structure of the porous adsorbent gradually leaches onto the surface of the porous adsorbent, and the same Ethyl alcohol evaporates from the surface, passes through the permeable holes, and is released in predetermined amounts over a long period of time from the easily permeable leaching evaporation layer, making ethyl alcohol effective as a preservative even under low temperature conditions. Alcohol vapor concentration is maintained for a long period of time, allowing long-term storage. The water contained in the structure of the porous adsorbent is replaced by ethyl alcohol that is impregnated into the structure of the porous adsorbent, so water freezes within the structure of the porous adsorbent under low temperature conditions. There is no fear of ethyl alcohol impregnated into the porous adsorbent structure, and the leaching of the ethyl alcohol impregnated into the porous adsorbent structure onto the porous adsorbent surface is not inhibited by frozen water, and the ethyl alcohol leaches smoothly into the porous adsorbent structure. The impregnated ethyl alcohol can be evaporated smoothly. Ethyl alcohol, which is retained in an adsorbed state on the surface of the porous adsorbent, once leaches into the fibrous leaching and transpiration layer, which has a large impregnation saturation amount and transpiration amount. Even though ethyl alcohol is retained, the ethyl alcohol remains in a liquid state and does not drip down, making handling convenient and preventing contamination of preserved foods. The invention described in claim 2 is characterized in that ethyl alcohol is retained in the structure or surface of the porous adsorbent in an impregnated or adsorbed state, and the retained amount of ethyl alcohol is equal to the saturated amount of ethyl alcohol impregnated in the porous adsorbent. A porous adsorbent holding this ethyl alcohol is housed inside a bag, and this bag forms a permeable layer and a fibrous leaching/transpiration layer coated on the surface of this permeable layer. The permeable layer is made of a non-liquid-absorbing sheet with permeable holes through which ethyl alcohol passes in liquid form, and the food preservative is stored in the food package together with the food in close or close contact with the food. Since this is a food preservation method using a food preservative that is characterized by preserving food, it has the following effects. Ethyl alcohol held in an adsorbed state on the surface of the porous adsorbent passes through the permeation pores as a liquid and leaches into the fibrous leaching and transpiration layer, resulting in leaching and transpiration with a wide surface area formed on the surface of the permeation layer. Since ethyl alcohol evaporates from the layer at a high concentration, the evaporation rate of ethyl alcohol is fast in the early stages of storage, and even under low temperature conditions where ethyl alcohol is difficult to evaporate, ethyl alcohol vapor can be effective for preservative preservation around food in a short period of time. concentration is reached, and effective preservatives can be more reliably achieved even in the early stages of storage. After the alcohol held in an adsorbed state on the surface of the porous adsorbent evaporates, the ethyl alcohol held in the impregnated state within the structure of the porous adsorbent gradually leaches onto the surface of the porous adsorbent, and as the temperature increases A predetermined amount is transpired from the surface of the porous adsorbent depending on the conditions and the surrounding ethyl alcohol vapor concentration,
Liquid ethyl alcohol passes through easy-to-pass permeation holes and is released in a predetermined amount over a long period of time from the easy-to-pass leaching and evaporation layer around the food in close or close proximity, so even under low temperature conditions, In addition, even if the storage container is not completely sealed, or even if the storage container is opened or closed during storage, the vapor concentration of ethyl alcohol, which is effective for preservative purposes, will be maintained for a long period of time around the food in close or close proximity. Long-term storage becomes more reliable regardless of the type of storage container. The water contained in the structure of the porous adsorbent is replaced by ethyl alcohol that is impregnated into the structure of the porous adsorbent, so water freezes within the structure of the porous adsorbent under low temperature conditions. There is no fear of ethyl alcohol impregnated into the porous adsorbent structure, and the leaching of the ethyl alcohol impregnated into the porous adsorbent structure onto the porous adsorbent surface is not inhibited by frozen water, and the ethyl alcohol leaches smoothly into the porous adsorbent structure. The impregnated ethyl alcohol can evaporate more smoothly into the surroundings of the food in close or close proximity. Ethyl alcohol, which is retained in an adsorbed state on the surface of the porous adsorbent, once leaches into the fibrous leach/transpiration layer with a large impregnation saturation amount and transpiration amount.
Even though the porous adsorbent retains ethyl alcohol close to or above the impregnation saturation amount, and even though it is in close or close contact with the food, the ethyl alcohol does not drip down in liquid form. , and will not contaminate stored foods in close or close proximity. The effects of this invention will be made clearer by describing Examples and Test Examples of this invention. Example 1

[Table] A food preservative was obtained with the composition shown in Table 1 above. The preparation procedure was as follows: First, silica gel powder was immersed in 200 c.c. of ethyl alcohol and left in a sealed state for 5 hours or more to allow the ethyl alcohol to permeate into the silica gel powder, and then the silica gel was taken out. This silica gel was then placed in a bag-shaped permeable layer. In this case, the amount of ethyl alcohol contained in the permeable layer was 50 c.c., which exceeded the saturation amount of silica gel. This is because ethyl alcohol is retained on the surface of the silica gel and between the silica gel particles. The amount of ethyl alcohol accommodated was calculated by subtracting the amount after decantation from the amount before immersion in the silica gel. Example 2 The amount of ethyl alcohol in Example 1 was changed to 40c.c.
(114%)* A food preservative was obtained in the same manner as in Example 1. Example 3 The amount of ethyl alcohol in Example 1 was changed to 32 c.c. (90 c.c.
%) * A food preservative was obtained in the same manner as in Example 1. Example 4 The amount of ethyl alcohol in Example 2 was changed to 70c.c.
(200%) *A food preservative was obtained in the same manner as in Example 1. Comparative Example 1 The amount of ethyl alcohol in Example 1 was changed to 30 c.c. (86
%) * A food preservative was obtained in the same manner as in Example 1. Comparative Example 2 The amount of ethyl alcohol in Example 1 was changed to 77 c.c.
(220%) *A food preservative was obtained in the same manner as in Example 1. Comparative Example 3 Ethyl alcohol was placed in a plastic container and sealed with a cement mortar stopper to obtain a food preservative. Comparative Example 4 Absorbent cotton absorbing and impregnating ethyl alcohol was placed in a polyethylene bag, a cotton thread was inserted and fixed into the absorbent cotton, and its tip was made to protrude outside the polyethylene bag to obtain a food preservative. Comparative Example 5 Rice cake (5 cm x 5
cm
The pressure was reduced to 600 mg, and 600 mg of ethyl alcohol was injected into the container, which was vaporized and stored. Test Example 1 The food preservatives of Examples 1 to 4 and Comparative Examples 1 to 4 were left at temperatures of 0°C and 20°C, and the amount of vapor of ethyl alcohol was measured. The results are shown in Table 2-A and B. As is clear from these results, in Examples 1 to 4 and Comparative Example 2, the steam rise speed was higher than in Comparative Examples 1, 3, and 4, and the time required for the rise of the steam concentration necessary for preservation was shortened. I understand. In Comparative Example 2, there is no problem with the rate of rise of steam, but the ethyl alcohol is in liquid form and drips, making it inconvenient to handle. Test Example 2 Each example in a polyethylene bag (10cm x 10cm),
One piece each of the comparative example (5m x 5cm x 1
cm) and seal with heat seal.
The mold was left at a temperature of 20°C and 20°C, and the state of mold growth was visually observed over time. The results are shown in Table 3-A and B.

【table】

【table】

[Table] As is clear from the results, Examples 1 to 4,
In Comparative Example 2, the growth of mold was clearly suppressed compared to Comparative Examples 1 and 3 to 5, and by applying ethyl alcohol in a highly concentrated vapor state, it was possible to effectively exert its antiseptic function, and in particular, ethyl alcohol It can be seen that the antiseptic function can be effectively exhibited even in a low temperature atmosphere where alcohol is difficult to evaporate. Although Comparative Example 2 has no problem in terms of antiseptic function,
Ethyl alcohol is liquid and drips, making it inconvenient to handle. Example 6 and Comparative Example 6 Silicic acid (ethyl alcohol impregnation saturation amount, oil absorption amount
1.6 g/g) powder, 10 x 8 (cm) Japanese paper and polyethylene (16 100μ holes, 32 g/m ² ) laminated bag with holes, 10 x 8 (cm) Japanese paper and polyethylene (32 g/m 2 ) The relationship between the transpiration rate of alcohol and the pores of polyethylene was investigated using a laminated bag with no holes (m ² ). As Example 6, 5 g of silicic acid was impregnated with 10 g of alcohol (125% impregnation) and filled into the perforated laminated bag. As Comparative Example 6, 10 g of alcohol was filled into the holeless laminated bag as a liquid. Three samples were prepared for each, and the transpiration of alcohol was examined every hour. The results of three average values are shown in Table 4. The results are expressed as a percentage of the amount of alcohol evaporated from the initial filling amount.

[Table] The non-perforated laminated bag of the comparative example has extremely poor volatility.
In addition, in one of the samples, there was an invisible gap when the bag was sealed, and almost all of the ethyl alcohol flowed out of the bag in liquid form within 2 hours. This sample was excluded from the calculation of the average value. As is clear from the above Examples and Comparative Examples, the food preservative according to the present invention is shown in Comparative Example 1 in which the food preservative of the present invention is absorbed and adsorbed below the saturation absorption point of an absorber or adsorbent such as ethyl alcohol powder. Unlike conventional preservatives, the liquid portion of ethyl alcohol adsorbed above the saturation adsorption point of the adsorbent oozes out through the permeation holes of the perforated laminated bag, and is absorbed and diffused in liquid form into the leaching evaporation layer. Since the ethyl alcohol is diffused as a gas, the rate of evaporation of ethyl alcohol is extremely fast.Moreover, when the liquid portion of the adsorbent, which has been allowed to exceed the saturation adsorption point, evaporates, the ethyl alcohol in the adsorbent evaporates, resulting in a fast-acting and antiseptic effect. It is long-term. In addition, in the case of the conventional example shown in Comparative Example 6, in which liquid ethyl alcohol was directly impregnated into a laminated bag with a two-layer structure and no holes, ethyl alcohol evaporated poorly or there were no holes. However, if there is a pinhole or heat seal error in the laminated bag, ethyl alcohol will flow out of the laminated bag in a liquid state within a short period of time, staining the food, and having no preservative effect. Unlike the conventional example,
The liquid portion that has adsorbed ethyl alcohol above the saturation adsorption point of the adsorbent oozes out through the holes in the permeable layer of the laminated bag with holes, is absorbed and diffused in liquid form into the leaching evaporation layer, and is diffused as a gas from this leaching evaporation layer. The rate of evaporation of ethyl alcohol from
Moreover, the liquid portion that has been adsorbed above the saturation adsorption point is about 10 to 20% of the total ethyl alcohol, so even if there is a pinhole or heat seal error, the ethyl alcohol can be removed from the laminated bag within a short time. It can be seen that the present invention has stable ethyl alcohol volatilization performance because it does not flow out completely in liquid form, but is simply absorbed and diffused in liquid form into the leaching evaporation layer, and is diffused as a gas from this leaching evaporation layer.

Claims (1)

[Scope of Claims] 1. Ethyl alcohol is retained in the structure or surface of the porous adsorbent in an impregnated or adsorbed state, and the retained amount of ethyl alcohol is 90 to 200% of the saturated amount of ethyl alcohol impregnated in the porous adsorbent. %, and a porous adsorbent holding this ethyl alcohol is housed inside a bag body, and this bag body consists of a permeable layer and a fibrous leaching/transpiration layer coated on the surface of this permeable layer, and the above-mentioned The permeable layer is a food preservative made of a non-absorbent sheet with permeable holes that allow ethyl alcohol to pass through in liquid form. 2. Ethyl alcohol is impregnated or retained in an adsorbed state within the structure or on the surface of the porous adsorbent, and the amount of ethyl alcohol retained is 90 to 200% of the saturated amount of ethyl alcohol impregnated in the porous adsorbent. A porous adsorbent holding alcohol is housed inside a bag body, and this bag body consists of a permeable layer and a fibrous leaching and transpiration layer coated on the surface of the permeable layer, and the permeable layer is a non-liquid absorbing layer. A food preservative comprising a plastic sheet with permeable holes through which ethyl alcohol passes in liquid form is housed in a food package together with the food in close or close contact with the food, thereby preserving the food. How to preserve food using preservatives.