JPS6132940B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing candied chestnuts, and more specifically, candied chestnuts prepared using a sugar solution with a sugar content of 20 to 65 are dried by micro-irradiation heating, and then ventilated to maintain shelf life as a food material. ,
The present invention also relates to a method for quickly and efficiently producing dried chestnut candied vegetables, which is highly versatile. In Japan, chestnuts are produced in large quantities in limited production areas during the limited season from September to October, but there are very few suitable methods for preserving them. Chestnuts are mainly composed of carbohydrates consisting of starch and sugars, have a mild flavor, are susceptible to deterioration, and have a fragile structure. For this reason, chestnut-based food materials are almost never boiled in water and canned, but are steamed with a large amount of cane sugar to retain their flavor. A method of making candied chestnuts with a long shelf life, a method of bottling or canning ground chestnut paste, etc. A method of drying the chestnuts, putting them in a foil, and then removing the skin and astringent skin and pounding the chestnuts. It was limited to methods such as making chestnuts. However, products produced by these conventional methods lacked versatility as food materials. For example, the manufacturing method for chestnuts is extremely complicated.
It has a special flavor and requires a long time to regenerate when used, so it is only used for New Year's and other celebrations. In addition, chestnut candied and chestnut paste are used as raw materials for making Western confectionery such as chestnut yokan and Mont Blanc, and cooked rice such as chestnut rice and chestnut okowa, but in order to retain the flavor and have shelf life, a large amount of cane sugar is used. Because it is manufactured by adding sugars such as, the sweetness is too strong and unsuitable as an ingredient for cooked rice. Furthermore, candied chestnuts and chestnut paste bottled or canned lose their shelf life after being opened, and are inconvenient to handle when divided into small portions for commercial processing. Furthermore, in many cases, even though only chestnuts are required for use, more than 30% by weight of a concentrated sugar solution is added to the chestnuts in order to preserve them, resulting in a lot of waste during storage and transportation.
There is no effective way to use this sugar. In addition, packaging containers such as storage bottles and cans pose a pollution problem when disposed of after use. The present inventors have completed the present invention as a result of extensive research in order to solve the above-mentioned drawbacks and develop a method for processing chestnuts that has sufficient storage stability, easy restorability, and excellent versatility. It was reached. According to the present invention, (1) Even if the moisture content of dried chestnut products is up to 15% by weight, no deterioration occurs due to microorganisms, especially mold;
It has sufficient storage stability. (2) It can be easily returned to the state of candied chestnuts, which is the raw material. (3) Since the sugar content of the sugar solution used in the production of candied chestnuts can be selected from a wide range of 20 to 65, from the conventional 53-65, it is possible to make candied chestnuts with less sweetness, making them widely used as food ingredients. be able to. (4) Since it is not necessary to store it in a specific container, it is easy to store and transport, and it is also easy to subdivide. Dried chestnut candied vegetables having the following characteristics are provided. The present invention will be explained in detail below. The present invention involves boiling chestnuts, draining the sugar solution, cutting the chestnuts if necessary, heating them with microwaves, drying them to a moisture content of 15 to 25% by weight, and then ventilating the chestnuts at a temperature of 90°C or less. The present invention provides a method for producing candied chestnuts, which is characterized by drying to a final moisture content of 15% or less. In the present invention, candied chestnuts are used as a raw material, but conventional manufacturing methods can be applied except that a sugar solution with a sugar content of 20 to 65 can be used in producing candied chestnuts.
That is, it is produced by boiling peeled chestnuts in water, then replacing the water with sugar solution, steaming, and soaking them. The sugar solution used at this time is prepared from one or more of sucrose, glucose, fructose, and high fructose sugar, and dextrin, starch syrup, etc., if necessary. When drying candied chestnuts boiled in honey using a sugar solution with a sugar content of 20 to 65, according to the hot air drying method, which is a representative method of traditional ventilation drying, there are various factors such as sample volume, air flow rate, and outside air humidity. However, as shown in Table 1 below, the drying efficiency is extremely poor. Moreover, as the surface dries, the internal structure of the chestnut becomes dense, making it difficult to dry, and it takes 60 degrees Celsius to reach the minimum moisture content of about 15% by weight in order to prevent the growth of mold and preserve it. It takes about 15 hours at 90°C and about 8 hours at 90℃. Note that even in this case, an undried portion remains in the center.

Use [Table] Furthermore, even if chestnuts are of the same variety and origin, they are usually mixed with chestnuts that are extremely difficult to dry. If chestnuts are dried at a high temperature of 90°C or higher for a long period of time, the chestnuts will turn orange overall and their color will deteriorate significantly. The present inventors investigated the drawbacks that would occur when candied chestnuts were dried using the conventional hot-air drying method as described above, and found that they could solve the above problems by first heating and drying candied chestnuts by microwave irradiation and then by ventilation drying. We have found that the problem can be solved. When candied chestnuts are irradiated with microwaves, the candied chestnuts are heated and dried starting from the center. When heating and drying by microwave irradiation, it is necessary to keep the water content within the range of about 15 to 25% by weight. Chestnuts will burn if they are dried until the moisture content after heating is less than 15% by weight. In addition, if drying is stopped when the moisture content exceeds 25% by weight, the microwave irradiation time will be too short and sufficient sterilizing effect will not be obtained, and the second stage of ventilation drying will require a long time, which is preferable. do not have. When dried by microwave irradiation and heating, the center of the candied chestnuts is dry, but the surface of the chestnuts may be insufficiently dried. In particular, when small chestnuts are mixed in, which are caused by boiling during cutting or boiling in honey, they absorb less microwaves and have less internal thermal movement than large chestnuts, so their temperature rises less and they are left undried. There are many parts. Therefore, in the present invention, as a second step, it is necessary to uniformly dry the chestnuts from the surface by applying a conventional ventilation drying method such as hot air drying. This ventilation drying
This is done at a temperature of 90°C or lower to bring the final moisture content of candied chestnuts to 15% by weight or less. As a result, the water activity of candied chestnuts becomes less than 0.65, and has sufficient bactericidal effect.
In other words, it is possible to prevent the growth of the mold (Asspergillus manigini) that is most likely to occur on chestnuts. In the case where the process order of the drying method of the present invention described above is reversed, and after conventional ventilation drying is performed as a pre-process, microwave irradiation heating drying is performed as a post-process, the microwave irradiation heating drying step is performed. The drying efficiency is poor, and the candied chestnuts tend to burn easily, making it impossible to obtain the excellent effects intended by the present invention. As mentioned above, the spoilage of candied chestnuts due to microorganisms is mainly caused by mold, but the moisture content of candied chestnuts can be reduced by the method of the present invention before drying.
It was confirmed that if dried to 15% by weight or less, the water activity would be about 0.65 or less, there would be no deterioration due to mold, and there would be no problems with its storage. Candied chestnuts boiled in honey using a sugar solution with a sugar content of 20 to 65 have a moisture content of about 42 to 43% by weight, and when candied chestnuts are dried by a combination of microwave irradiation heating and ventilation drying according to the present invention, For example, when heated with microwave irradiation for 210 seconds, the moisture content of candied chestnuts becomes about 17% by weight, and when dried by blowing hot air at 90℃, the moisture content decreases to 15% in about 1 hour.
It is about % by weight. As described above, according to the present invention, candied chestnuts are first subjected to microwave irradiation heating as a pre-process to dry them uniformly from the center, and then dried from the surface using a conventional ventilation drying method such as hot air drying as a post-process. By carrying out this process, it is possible to produce a dried chestnut candied product that has a long shelf life in an extremely short time and with thermal efficiency by supplementing the drying from the center part in the previous step and performing final drying. The dried candied chestnuts obtained by the present invention can be stored by storing them in a non-hygroscopic packaging material to maintain the moisture content at the end of drying by the method of the present invention, or by freezing or refrigerating them. No special consideration is required for preservation, such as placing it in a heat-resistant and water-resistant container and heating it after sealing. Examples of non-hygroscopic packaging materials include, for example, films made of synthetic resin, and moisture-resistant containers such as bag fiber drums made from such films.
Long-term storage is possible by simply blocking humidity. The dried product of candied chestnuts according to the present invention thus obtained can be returned to the state of moist steamed chestnuts by simple processing. The dried product of candied chestnuts according to the present invention returns to a moist state extremely quickly and is far superior in restorability, compared to raw chestnuts and boiled chestnuts prepared by the method of the present invention. That is, according to the present invention in which candied chestnuts in which sugars have permeated and dispersed in the lees are dried, when the resulting dried candied chestnuts are returned to a moist state by adding water again, water tends to rapidly permeate into the sugars, so that the dried chestnuts cannot be rehydrated. It's early. An example of a method for returning dried candied chestnuts to a moist state according to the present invention is to immerse the dried candied chestnuts in a concentrated sugar solution prepared separately in advance, heat them with microwave irradiation for 2 minutes, and then leave them for 15 minutes. Chestnuts can be easily returned to their candied state. In addition, after mixing the dried chestnut candied rice in a certain weight ratio with the washed rice just before cooking in an electric pot that has been weighed and watered, it is cooked in a gas rice cooker for about 15 minutes.
Chestnut rice can be made very easily by boiling the rice in an electric pot for about 25 minutes, then steaming it in the usual manner. The method for producing candied dried chestnuts of the present invention is to make candied chestnuts with a low sweetness by boiling chestnuts in honey using a sugar solution that has reduced the sugar content to about 1/3 of the sugar solution normally used so that the chestnuts do not disintegrate. It is also possible to apply it to
It is possible to obtain candied chestnuts with sufficient storage stability. Such a product can be used as a food material for cooking cooked rice, and can be made into a versatile product. However, chestnuts made from raw chestnuts or steamed chestnuts that are subjected to microwave irradiation heating and ventilation drying shrink significantly after drying and have a very poor recovery. In addition, when candied chestnuts dried by other drying methods, such as freeze-drying, are returned before cooking or cooked together with washed rice, the texture changes significantly, and the candied chestnuts according to the present invention are Or, when rice is cooked, it becomes fluffy, but it is flat and fluffy, and the desired texture is not achieved. Hereinafter, the present invention will be explained in more detail with reference to the following examples. Example 1 1000g of chestnuts with their skins and astringent skins peeled were placed in a small double boiler, 1500g of water was added thereto, and the temperature was raised to 65°C in 1 hour to degas the chestnuts. After that, change the water and add new water.
1500g was added and the temperature was raised to 98°C in 1 hour. Next, it was boiled for 40 minutes at 98°C to remove the scum and ripen. Thereafter, they were washed with water, drained, and poured with 1,300 g of a honey-boiled liquid with a sugar content of 65 that had been prepared in advance with sucrose, and boiled with honey at 96°C for 40 minutes. Just put it in the double pot.
The chestnuts were left to stand for 15 hours and made into candied chestnuts. Pour the candied chestnuts onto a sieve to remove the sugar solution, then cut the whole chestnuts into 1/2, place the 1/2 cut pieces on a Teflon sheet, and place it in a 2450MHz, 1KW microwave irradiation heating machine. The beaker was filled with water and heated and dried by irradiation with microwaves for 210 seconds while absorbing excess microwaves until the water content was 17% by weight. Next, this dried product is heated to 90% using a hot air dryer.
Dry candied chestnuts with a final moisture content of 13% by weight (water activity 0.54) by drying with hot air at ℃ for 1 hour to achieve a uniform finish.
Obtained 560g. This product had good shelf life. 100g of candied dried chestnuts obtained by the above method were immersed in 200g of a sugar solution with a sugar content of 60 prepared in advance, heated with microwave irradiation for 2 minutes while soaked, left for 15 minutes, and then sieved on a sieve. The candied chestnuts, which had the sugar solution removed and were reconstituted into candied chestnuts, were used in the production of chestnut cake. Example 2 Take 10kg of chestnuts with their skins and astringent skins peeled off in a double pot and boil them for 15 minutes.
Kg water was added and the temperature was raised to 65°C in 1 hour to degas the chestnuts. After that, change the water and add 15 kg of new water.
The temperature was raised to 98°C for 1 hour. Next, steaming was continued for 40 minutes at 98°C to remove bitterness and boil. After that, they were washed with water, drained, and poured with 13 kg of a honey-boiled liquid with a sugar content of 30 that had been prepared in advance with sucrose, and boiled with honey at 96°C for 40 minutes. The mixture was left in a double boiler for 15 hours to make candied chestnuts. Pour the candied chestnuts onto a sieve to remove the sugar solution, then pour in water to wash the surface.
Cut into 4 pieces, feed them on a conveyor at a rate of 150g/min, and heat them at 2450MHz in a microwave heating device.
It was dried by irradiating and heating with 4KW microwave for 5 minutes, and the moisture content was adjusted to 22% by weight. This dried product was then heated in batch-type hot air drying at 90°C for 1 hour.
After drying for 30 minutes, 5.550 kg of dried candied chestnuts with a final moisture content of 12% by weight were obtained. This product had good shelf life. 20g of candied dried chestnuts obtained by the above method and salt
Wash 2.0g of rice in advance (150g (1 cup)) and add 180g of water.
The rice was mixed with rice in an electric pot and cooked in the usual way until it was evenly cooked to obtain delicious chestnut rice with a fluffy texture. Example 3 1000g of chestnuts with their skins and astringent skins peeled were placed in a small double boiler, 1500g of water was added thereto, and the temperature was raised to 65°C in 1 hour to degas the chestnuts. After that, change the water and add new water.
1500g was added and the temperature was raised to 98°C in 1 hour. Next, boiling was continued for 40 minutes at 98°C to remove the scum and ripen. After that, wash with water, drain the water, and pour in a honey boiled liquid containing fructose with a sugar content of 60, which has been prepared in advance.96
The honey was boiled for 40 minutes at ℃. The chestnuts were left in a double boiler for 15 hours to make candied chestnuts. The whole chestnuts that had been boiled in the fructose solution were poured onto a sieve to remove the sugar solution. This whole chestnut was placed on a Teflon sheet, placed in a 2450MHz, 1KW microwave irradiation heating machine, and irradiated with microwaves for 240 seconds while filling a beaker with water to absorb excess microwaves, resulting in a moisture content of 16% by weight. It was heated and dried. Next, dry with hot air at 90℃ for 1 hour using a hot air dryer to remove the final moisture content.
600 g of dried chestnut candied with a concentration of 14% by weight was obtained. This product had good shelf life. 100g of dried candied chestnuts obtained by the above method were soaked in 200g of a sugar solution with a sugar content of 60 prepared in advance, heated under microwave irradiation for 2 minutes, left for 15 minutes, and cut the sugar solution on a sieve.Candied chestnuts Chestnuts returned to shape90
g was mixed with 210 g of yokan dough prepared separately, poured into a yokan boat, and cooled to obtain delicious chestnut yokan.

Claims (1)

[Claims] 1. After boiling the chestnuts, drain the sugar solution, cut the chestnuts if necessary, heat them with microwaves, dry them to a moisture content of 15 to 25% by weight, and further heat them at a temperature of 90°C. A method for producing candied chestnuts, which comprises drying through ventilation to reduce the final moisture content to 15% by weight or less. 2 The concentration of the sugar solution used when candied chestnuts is 20
~65 The manufacturing method according to claim 1.