JP7634079B2 - Method for producing peanuts, method for pretreating peanut seeds, method for improving flavor of peanuts, and method for suppressing leakage of components from the thin skin of peanut seeds - Google Patents

Description

The present invention relates to a method for producing peanuts, a method for pre-treating peanut seeds, a method for improving the flavor of peanuts, and a method for suppressing the leakage of components from the thin skin of peanut seeds.

Seeds of various plants are highly nutritious and have a good flavor, and have been consumed for many years. Such seeds can be processed to improve their palatability, etc.
There are various known methods for processing seeds, including a process for separating the thin skin (also called "astringent skin") on the surface of the seed. For example, Patent Document 1 describes a process for soaking almond kernels in hot water and then separating the astringent skin.

Japanese Patent Application Laid-open No. 62-239964

For peanuts, one commonly used method for separating the thin skin from the seed is to immerse the entire seed in hot water and then separate the skin.

However, the inventors have found that such soaking can cause components contained in the peanut seeds to leach out, potentially impairing the flavor, etc.

The present invention was made in consideration of the above situation, and its objective is to provide technology that can suppress the leakage of components contained in peanut seeds.

The inventors discovered that the above problems can be solved by spraying water vapor under certain conditions when separating peanut seeds, and thus completed the present invention. Specifically, the present invention provides the following:

(1) A spraying step of spraying water vapor of 65° C. or higher onto the surface of a peanut seed including an embryo and a thin skin covering the surface of the embryo for 50 seconds to 400 seconds;
After the spraying step, a peel separation step of separating the peel;
Including,
The manufacturing method of peanuts.

(2) A spraying step of spraying water vapor at 65°C or higher onto the surface of a peanut seed, including the embryo and the thin skin covering the surface of the embryo, in an amount that results in a water absorption of 2 g or more per 100 g of the seed;
After the spraying step, a peel separation step of separating the peel;
Including,
The manufacturing method of peanuts.

(3) A manufacturing method described in either (1) or (2), further comprising a step of recovering the skin after the skin separation step.

(4) A method for pretreatment of peanut seeds, comprising the steps of:
The seed includes an embryo and a membrane covering a surface of the embryo,
The pretreatment method includes a step of spraying water vapor at 65° C. or higher on the surface of the seeds for 50 seconds to 400 seconds.
Pretreatment methods.

(5) A spraying step of spraying water vapor of 65° C. or higher onto the surface of the peanut seed, including the embryo and the thin skin covering the surface of the embryo, for 50 seconds to 400 seconds;
After the spraying step, a peel separation step of separating the peel;
Including,
How to improve the flavor of peanuts.

(6) A spraying step of spraying water vapor of 65° C. or higher onto the surface of the peanut seed, including the embryo and the thin skin covering the surface of the embryo, for 20 seconds to 400 seconds;
After the spraying step, a peel recovery step of recovering the peel;
Including,
A method for inhibiting leakage of components from the thin skin of peanut seeds.

The present invention provides a technology that can suppress the leakage of components contained in peanut seeds.

FIG. 1 is a diagram comparing the cross sections of peanut seeds when soaked or sprayed.

The following describes in detail an embodiment of the present invention, but the present invention is not limited thereto.

<Peanut manufacturing method>
The method for producing peanuts of the present invention (hereinafter, simply referred to as the "production method of the present invention") includes the following two aspects. These aspects are common to each other except that the conditions for the spraying step are different.
(First aspect)
A spraying step of spraying water vapor of 65° C. or higher onto the surface of a peanut seed including an embryo and a thin skin covering the surface of the embryo for 50 seconds to 400 seconds;
After the spraying step, a peel separation step of separating the peel;
Including,
The manufacturing method of peanuts.
(Second Aspect)
A spraying step of spraying water vapor at 65° C. or higher onto the surface of a peanut seed including an embryo and a thin skin covering the surface of the embryo in an amount that results in a water absorption of 2 g or more per 100 g of the seed;
After the spraying step, a peel separation step of separating the peel;
Including,
The manufacturing method of peanuts.

In all embodiments, the manufacturing method of the present invention includes a step of spraying water vapor onto the surface of peanut seeds.
"Steam spraying" refers to spraying a mist of liquid (water) onto a target (peanut seeds in this invention), and is clearly distinguished from "immersion," which involves immersing a target in liquid contained in a container or the like.

Conventionally, the thin skin of peanut seeds has been separated (removed) by immersing the skin-covered seeds in hot water to absorb water and soften them, and then using a peeling machine (roll type or vibrating type) or by hand peeling.
However, the present inventors found that such soaking causes components contained in peanut seeds to flow out, such as water-soluble components such as sucrose and glutamic acid.
Since sucrose and glutamic acid provide sweetness and umami, respectively, there is concern that the sweetness and umami of the seeds may be reduced when using conventional methods.

As a result of further investigations, the inventors have discovered that, instead of immersing in hot water, spraying with water vapor at 65°C or higher under specified conditions can efficiently separate the thin skin of peanut seeds and also suppress the loss of components contained in the peanut seeds.

In the present invention, the "components contained in peanut seeds" are not particularly limited, but include components (particularly water-soluble components) that are normally contained in plant seeds (eg, embryo, pellicle, etc.).
Specific examples include sucrose, glutamic acid, polyphenols, and the like.

In the present invention, "suppression of outflow of components contained in peanut seeds" encompasses suppression of a decrease in the content of components (particularly water-soluble components) contained in peanut seeds after spraying water vapor onto the peanut seeds, as compared to peanut seeds treated by a conventional method (e.g., immersion in hot water of 90°C or higher for 80 seconds or more).
Whether the outflow of components contained in peanut seeds is being suppressed will be determined using high performance liquid chromatography (HPLC) and sensors (chemical sensors, biosensors).

According to the present invention, the outflow of components (sucrose, glutamic acid, etc.) contained in the embryo of the peanut seed is suppressed, so that peanuts having a sweeter taste and tastiness than conventional peanuts can be obtained.
Furthermore, according to the present invention, the outflow of components (such as polyphenols) contained in the skin of the peanut seeds is suppressed, so that the amount of useful components retained in the skin is greater than in the past.

The manufacturing method of the present invention is described in detail below.

(peanut seeds)
The production method of the present invention is a method for producing peanuts from peanut seeds.

"Peanut" (scientific name: Arachis hypogaea) is a plant of the genus Arachis in the subfamily Fabaceae, and refers to the entire plant body including edible parts (seeds, etc.) and inedible parts (shells, pods, etc.).

In the present invention, the "peanut seed" refers to the main edible part of the peanut, and generally includes the embryo, the membrane, the cotyledons, and the like.
The peanut seeds subjected to the production method of the present invention include an embryo and a thin skin covering a part or the entire surface of the embryo.

In the present invention, "peanuts" refers to peanut seeds from which the thin skin has been peeled off (mainly the embryo). However, this does not exclude the case where the thin skin is mixed in with the peanuts obtained by the manufacturing method of the present invention.

The origin and variety of peanuts used in the present invention are not particularly limited.

The amount of peanut seeds used in the manufacturing method of the present invention is not particularly limited and may be a small amount (one or a few) or a large amount (factory production level).

At the time of the spraying process, the peanut seeds are usually in a shelled state.
From the viewpoint of easily achieving the effects of the present invention, it is preferable that the peanut seeds have not been subjected to any artificial steps (washing, etc.) other than the separation of the shells at the time of being subjected to the spraying step.

(Spraying process)
The spraying steps in the first and second embodiments will be described below.

[Spraying step in the first embodiment]
In the first embodiment, water vapor at 65° C. or higher is sprayed onto the surface of peanut seeds for 50 to 400 seconds.

In the present invention, the "temperature of water vapor" may be a constant temperature within a range that satisfies the requirements of the present invention, or it may not be a constant temperature.

In the present invention, the "spray time of water vapor" refers to the total time for which water vapor is sprayed onto the surface of peanut seeds, and the spray time may be continuous or intermittent. If the spray time is intermittent, the spray interval is adjusted so that the seed surface does not dry out, in order to prevent the thin skin from drying out.

By setting the temperature of the steam to 65° C. or higher, the thin skins of the peanut seeds can be sufficiently absorbed with water, and the thin skins can be efficiently separated.
The lower limit of the temperature of the water vapor is preferably 70° C. or higher, and more preferably 90° C. or higher.

From the viewpoint of preventing deterioration of the peanut seeds and the outflow of ingredients (particularly sucrose, glutamic acid, and polyphenols), the temperature of the steam does not need to be excessive.
The upper limit of the temperature of the water vapor is preferably 210° C. or lower, more preferably 90° C. or lower.

By spraying the steam for a period of 50 to 400 seconds, the thin skin of the peanut seeds can be sufficiently absorbed while preventing the loss of ingredients.

From the viewpoint of more efficient separation of the peanut seed membrane, the lower limit of the water vapor spray time is preferably 60 seconds or more, more preferably 180 seconds or more.

From the viewpoint of further suppressing the outflow of peanut seed components (especially sucrose, glutamic acid, and polyphenols), the upper limit of the water vapor spray time is preferably 300 seconds or less, more preferably 240 seconds or less.

The total amount of water vapor sprayed onto the peanut seeds can be adjusted accordingly.
From the viewpoint of making it easier to achieve the effects of the present invention, the total amount of water vapor sprayed on the peanut seeds may satisfy the conditions of the spraying step in the second embodiment described below (i.e., an amount that results in water absorption of 2 g or more per 100 g of seeds).

[Spraying step in the second embodiment]
In the second embodiment, water vapor at 65° C. or higher is sprayed onto the surface of peanut seeds in an amount that results in water absorption of 2 g or more per 100 g of seeds.

In the present invention, the "amount of water absorption" is determined by measuring the change in mass of the peanut seeds before and after water absorption. In other words, the increased mass of the peanut seeds after water absorption corresponds to the amount of water absorption.

By setting the temperature of the steam to 65° C. or higher, the thin skins of the peanut seeds can be sufficiently absorbed with water, and the thin skins can be efficiently separated.
The lower limit of the temperature of the water vapor is preferably 70° C. or higher, and more preferably 90° C. or higher.

From the viewpoint of preventing deterioration of the peanut seeds and the outflow of ingredients (particularly sucrose, glutamic acid, and polyphenols), the temperature of the steam does not need to be excessive.
The upper limit of the temperature of the water vapor is preferably 210° C. or lower, more preferably 95° C. or lower.

When the amount of water vapor absorbed is 2 g or more, the thin skin of the peanut seeds can be sufficiently absorbed, and the thin skin can be efficiently separated.
The lower limit of the amount of water vapor absorption is preferably 2 g or more, and more preferably 4 g or more.

In order to prevent the outflow of peanut seed components (especially sucrose, glutamic acid, and polyphenols), the amount of water absorption is adjusted so as not to be excessive.
The upper limit of the water absorption is preferably 7 g or less, more preferably 5 g or less.

The time for spraying the peanut seeds with steam can be adjusted appropriately.
From the viewpoint of making it easier to achieve the effects of the present invention, the spraying time for the peanut seeds may satisfy the above-mentioned condition of the spraying step in the first embodiment (i.e., 50 seconds or more and 400 seconds or less).

[Other conditions in the spraying process]
In each of the first and second embodiments, other conditions in the spraying step are not particularly limited, and conditions conventionally known in the field of food production and the like can be adopted.
For example, the following conditions may be adopted:

In the spraying step, a part or the entire surface of the peanut seeds is brought into contact with water vapor.
To facilitate contact, the spraying process may involve moving the steam nozzle and/or agitating the peanut seeds.

Methods for spraying water steam include, for example, using a steamer or a hose (connected to the boiler supply steam).

In the present invention, an embodiment in which the conventional method (thin skin separation by immersion) is carried out in addition to the spraying step in the present invention is not excluded.
However, from the viewpoint of easily achieving the effects of the present invention, the production method of the present invention does not include a step of soaking peanut seeds in water (particularly, hot water of 90° C. or higher) for 80 seconds or more.

(Thin skin separation process)
After the spraying process, the peanut seeds are subjected to a dehulling process to separate the hulls.
This process yields peanuts and skins separately.

The interval between the spraying step and the skin separation step is not particularly limited.
However, the peanut seed membrane is easy to remove when it is in a softened state (i.e., when it has absorbed water from the spraying process). Therefore, it is preferable that the interval between the two steps is short enough to keep the membrane in a softened state. It is also preferable that no other steps are included between the two steps.

Methods for separating the thin skin include using a peeling machine (roll type or vibrating type) or peeling by hand.

After the skin separation step, drying or the like may be carried out as appropriate.
The drying method is not particularly limited, but may be a method using an electric fan or the like.

After the skin separation step, the resulting peanuts can be consumed as is or can be further processed.
The peanuts are inhibited from losing components (especially sucrose and glutamic acid) and have excellent flavor (sweetness, umami, etc.).

After the peel separation step, the separated peel may be discarded or may be collected and stored.
The thin skin prevents components (such as polyphenols) from leaking out, so it retains a greater amount of useful components than conventional skins.
Therefore, the skin can be used as a source of useful components (such as polyphenols). For example, the skin can be subjected to extraction to obtain useful components.

<Pretreatment method for peanut seeds>
As described above, the spraying step in the present invention is useful as a method for allowing peanut seeds to absorb water while suppressing the outflow of components contained in the peanut seeds.
Therefore, the present invention also encompasses a method for pretreating peanut seeds comprising the spraying step of the present invention (the spraying steps in the first and second aspects).

In the present invention, "pretreatment" includes pretreatment for peel separation.

<How to improve the flavor of peanuts>
As described above, the spraying step in the present invention is useful as a method for suppressing the outflow of components contained in peanut seeds and improving the flavor of the resulting peanuts.
Therefore, the present invention also includes a method for enhancing the flavor of peanuts, which includes the spraying step of the present invention (the spraying step in the first and second aspects) and also includes a skin separation step of separating the skins after the spraying step.

In the present invention, "peanut flavor" includes sweetness derived from sucrose, etc., umami derived from glutamic acid, etc.

<Method for preventing leakage of components from the thin skin of peanut seeds>
As described above, the spraying step in the present invention is useful as a method for suppressing the outflow of components contained in peanut seeds.
Therefore, the present invention also includes a method for inhibiting the leakage of components from the peanut seed skins, which includes the spraying step in the present invention (the spraying step in the first and second aspects) and also includes a skin recovery step of recovering the skins after the spraying step.
However, in the component outflow suppression method, the lower limit of the spraying time in the spraying step may be 20 seconds or more, preferably 30 seconds or more, more preferably 40 seconds or more, and even more preferably 50 seconds or more.
In addition, it is preferable that the upper limit of the spraying time in the spraying step is not excessive from the viewpoint of suppressing outflow of the components, and for example, it may be preferably 400 seconds or less, more preferably 330 seconds or less, even more preferably 300 seconds or less, and even more preferably 180 seconds or less.

In the present invention, "components of the peanut seed membrane" include polyphenols.

The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to these examples.

<Making peanuts>
Peanuts were prepared from peanut seeds in the following manner.

(1) Preparation of peanut seeds Peanuts with shells were purchased, and the shells were removed to remove the peanut seeds. Each seed contained an embryo and a thin layer covering the surface of the embryo.

(2) Spraying of Steam onto Peanut Seeds Peanut seeds (100 g for each example) were placed on a net, and steam was evenly applied to the surface of the seeds using a hose connected to the steam supplied to a boiler.
The water vapor release rate was kept constant in each example.
The temperature of the steam was set in the range of 50° C. to 110° C. (see the "Steam temperature" section in the table below).
The spray time of the water vapor on the peanut seeds was set in the range of 30 seconds to 330 seconds (see the "Spray Time" section in the table below).

Additionally, the amount of water vapor sprayed onto the peanut seeds was confirmed based on the amount of water absorbed immediately after spraying was completed.
As a result, when the spray time of peanut seeds and steam was 50 seconds or more and the temperature of the steam was 65°C or higher, the amount of water absorbed was 2 g or more (maximum about 5 g) per 100 g of seeds in all cases.
On the other hand, when the peanut seeds were sprayed with steam for less than 50 seconds or the temperature of the steam was less than 65° C., the amount of water absorbed was less than 2 g per 100 g of seeds in all cases.

The amount of water absorption was calculated by calculating the absorption rate based on the following formula, and the obtained value was specified as the amount of water absorption per 100 g of seeds.
Water absorption rate (%)=(mass of peanuts immediately after spraying process−mass of peanuts before spraying process)/mass of peanuts before spraying process×100

(3) Separation of Membranes Immediately after spraying with steam, the membranes were separated from the peanut seeds by hand peeling to obtain peanuts.
The separated skins were stored at room temperature until they were subjected to the following evaluation.

(4) Drying of Peanuts The peanuts were dried using a fan until no longer moist, and then stored at room temperature until used for the following evaluation.

<Various evaluations>
The ease of separation of the skins during the peanut production process, and the resulting peanuts and skins were evaluated by the following methods.

(1) Ease of Separating the Skin In the process of preparing peanuts, the ease of separating the skin (ease of peeling the skin) in "(3) Separating the skin" was evaluated according to the following criteria. The results are shown in Table 1.

[Criteria for ease of peel separation]
: The skin is very easy to peel off.
A: The skin is easy to peel off.
△: The skin is somewhat easy to peel off.
×: The skin cannot be peeled off.

As shown in Table 1, when spraying was performed under the conditions of the present invention, the thin skin was easily peeled off.
In particular, the skin was easier to peel when the steam temperature was 70° C. or higher and the steam spray time was 60 seconds or longer. Furthermore, the skin was significantly easier to peel when the steam temperature was 90° C. or higher and the steam spray time was 180 seconds or longer.

On the other hand, when spraying was carried out in a state that did not satisfy the conditions of the present invention, the thin skin was difficult to peel off.
In particular, when the steam temperature was below 65° C., the peanut seeds did not absorb enough water even when the spraying time was extended, and the skin did not soften, making it impossible to peel the skin.
Furthermore, when the spraying time was less than 50 seconds, the peanut seeds did not absorb enough water even when the steam temperature was increased, and the skin did not soften, making it impossible to peel the skin.

(2) Flavor of peanuts Peanuts were eaten by experienced panelists, who were then asked to evaluate the flavor (sweetness and umami) of the peanuts according to the following criteria. The results are shown in Table 2.

[Peanut flavor standards]
◎: Strong sweetness and umami flavor.
◯: Sweetness and umami are noticeable.
△: Sweetness and umami are slightly noticeable.
×: No sweetness or umami taste is observed.

As shown in Table 2, when spraying was performed under the conditions of the present invention, the resulting peanuts had a sweet and umami taste.
In particular, clear sweetness and umami were observed when the temperature of the steam was around 90° C. Furthermore, clear sweetness and umami were observed when the spray time of the steam was 180 seconds or more and 240 seconds or less.
Furthermore, when the temperature of the steam was around 90° C. and the spray time of the steam was 180 seconds or more and 240 seconds or less, a significant sweetness and umami were observed.
However, if the water vapor spray time was long, the components in the seeds were washed out, and the sweetness and umami flavor tended to decrease slightly.

On the other hand, when spraying was carried out without satisfying the conditions of the present invention, the thin skin was difficult to peel, making it difficult to evaluate the sweetness and umami of the peanuts.

(3) Amount of polyphenols in the skin During the peanut production process, the amount of polyphenols in the skin recovered in "(3) Separation of the skin" was measured based on the Folin-Ciocalteu method.
In addition, the amount of polyphenols in the skins of peanut seeds that had not been sprayed with steam (untreated skins) was also measured.

The measurement results obtained were evaluated according to the following criteria. The results are shown in Table 3.
However, no measurement was performed for cases in which the skin could not be separated at all.
In Table 3, some of the measurement results of the polyphenol amount are shown in parentheses at the bottom of each column.

As a "control" (treatment based on the conventional method), instead of "(2) spraying steam onto peanut seeds" during the peanut production process, peanut seeds were placed in a container filled with hot water (90°C) and the entire peanut seeds were immersed in the hot water for 180 seconds, and the amount of polyphenols in the resulting skin was also measured.
As a result, the amount of polyphenols was found to be "0%" (i.e., no polyphenols remained in the skin).

[Standards for polyphenol content in skin]
⊚: The amount of polyphenols in the skin is 50% or more of the amount of polyphenols in the untreated skin.
◯: The amount of polyphenols in the skin is 30% or more and less than 50% of the amount of polyphenols in the untreated skin.
Δ: The amount of polyphenols in the skin is 10% or more and less than 30% of the amount of polyphenols in the untreated skin, or the peanut has a bitter taste (transfer of polyphenols from the skin to the embryo).
×: The amount of polyphenols in the skin is less than 10% of the amount of polyphenols in the untreated skin, or the skin cannot be separated at all, or the peanut has a strong bitter taste (transfer of polyphenols from the skin to the embryo).

As shown in Table 3, when spraying was performed under the conditions of the present invention, the amount of polyphenols remaining in the skin was high.

On the other hand, when spraying was carried out under conditions that did not satisfy the conditions of the present invention, not only was it difficult to peel the skin in the first place and difficult to recover the skin, but even if it could be recovered, the amount of polyphenols remaining in the skin was low.

<Reference: Conventional method>
For reference, peanuts were prepared by separating the membrane from peanut seeds using the conventional method described below.

(1) Preparation of peanut seeds Peanut seeds were prepared in the same manner as described above in <Preparation of peanuts>.

(2) Soaking of Peanut Seeds Peanut seeds were placed in a container filled with hot water (90° C.), and the entire peanut seeds were soaked in the hot water for 180 seconds.
When the amount of water absorbed after soaking was measured, it was found to be more than 20 g per 100 g of seeds.

(3) Separation of the skins and drying of the peanuts The skins were separated and the peanuts were dried in the same manner as in <Preparation of peanuts> above.

The evaluation was carried out in the same manner as in the above <Various Evaluations>, and the results are shown in the "Conventional Method" section of Table 4. Note that "Invention" in Table 4 is the result in the above <Various Evaluations>, where the water vapor temperature was 90°C and the spray time was 180 seconds.

As shown in Table 4, by satisfying the conditions of the present invention, not only is it easier to separate the skins, but the flavor of the peanuts is enhanced and the leakage of polyphenols from the skins is suppressed compared to the "conventional method."

Furthermore, when the amount of components leached from peanut seeds was measured using high performance liquid chromatography (HPLC), a significant decrease in the amounts of sucrose and glutamic acid was observed in the "conventional method" compared to before treatment (a 5-15% decrease in sucrose and a 1-5% decrease in glutamic acid).
On the other hand, no changes in these amounts were observed in the "present invention."

In this example, the cross-sections of the peanuts of the "conventional method" and "present invention" in Table 4 were observed under an electron microscope to see how they changed before and after immersion or spraying. The results are shown in FIG.
As shown in FIG. 1, the "conventional method" showed expansion of the cross section and a large number of voids, whereas the "present invention" showed some voids, but there was little change from the cross section before spraying.

Claims (2)

A spraying step of spraying water vapor having a temperature higher than 80° C. and lower than 100° C. onto the surface of a peanut seed including an embryo and a thin skin covering the surface of the embryo for 180 seconds or more and 240 seconds or less ;
After the spraying step, a peel separation step of separating the peel;
Including,
How to improve the flavor of peanuts. 2. The method for enhancing the flavor of peanuts according to claim 1, wherein in the spraying step, the seeds are sprayed in an amount such that the seeds absorb 2 g or more of water per 100 g of the seeds.