【発明の詳細な説明】[Detailed description of the invention]
この発明は、特に酒造用原料米を得るに好適な
玄米、精米の洗浄処理法に関する。
酒造用原料米に要求される条件としては、酒
に異味、異臭を与える成分が含まれていないこ
と、蒸しが容易で麹の破精込がよく溶解糖化の
良いことなどが挙げられる。そして、異味、異臭
の原因は原料米に含まれる油脂（粗脂紡）、粳臭
成分、古米臭成分によるものであるこが判明して
おり、原料米中のこれら成分の含量を極力低くす
るようになされせいる。また、蒸しが均一で良い
蒸米を得るためには、原料米の吸水性が良くなけ
ればならない。
第１図に示したグラフは、精米歩合による精米
中の粗脂紡含量の変化を示すものであるが、この
グラフより、精米歩合が75％までは粗脂肪含量は
これに比例して急激に減少するが、75％以下とな
ると減少率は大幅に低下することがわかる。この
結果から現在、原料米は精米歩合で75〜73％程度
まで高度に精白し、臭気成分の低減および油脂含
量の低減を図つて、上記の要求を満している。
しかし、高度精白を行えば当然の事ながら原料歩
留が極めて悪くなり、酒造コストの上昇を招く。
また、精白の際に、原料米の胴割れ、破砕が多く
発生し、精米としての歩留も悪く、無効精白度合
が大きくなる。さらに、精白の際に大量の糠が発
生すらが、この糖の処理も大きな問題となつてい
る。
一方、ビール醸造原料としても米が多量に使用
されている。ビール醸造においても原料米中の油
脂含量は製品ビールの良否に大きく影響する。す
なわち、油脂含量が多いと、ビールの香味を極度
に損い、泡持ちも悪くし、さらに濾過性の低下、
糖化時間の延長、エキス収率の低下をきたす。し
たがつて、ビール用原料米としての油脂含量は１
％以下とされており、これに対応して精白されて
いる。
また、精白後の米穀は蒸きよう加工前、その表
面に付着している糠および糠臭の除去が必要とな
る。この除去処理には、水洗によるものが一般に
行われている。しかし、水洗による方法は、これ
を工業的に処理する場合大量の水を必要とすると
ともに排水が公害をもたらす欠点があつた。すな
わち、水洗後の排水はBODが非常に高く、油分
を含むためこれを浄化処理するのに多額の費用を
必要とする。また水洗によつて糖やアミノ酸の有
効成分が流出し、回収ができないという欠点もあ
る。
この発明は上記事情に鑑みてなされたもので、
酒造用原料米等の脱脂、脱臭を極めて効率よく行
うことができ、かつ米の胴割れや破砕等の損傷が
なく、しかも精米の水洗を行う必要のない米穀の
処理方法を提供すことを目的とするものである。
以下、この発明を詳細に説明する。この発明の
米穀の処理方法は、玄米、精米等の米穀を液状ま
たは超臨界状態の炭酸ガスに接触させるものであ
る。
まず、この発明に用いられる抽出溶剤である炭
酸ガスの性状について説明する。第２図は炭酸ガ
スの圧力一温度線図（PT−ダイアグラム）を示
すもので、炭酸ガスの温度、圧力に応じた各状態
（液体、固体、気体）が表示されている。図中TP
は三重点で三相が共存する温度、圧力を示し、
CPは臨界点で圧力（Pc）73.8バール（72.84Kg／
cm2）、温度（Tc）31.06℃である。この発明で用
いられる炭酸ガスは、第２図中斜線で示した範囲
内にあるもので、液状炭酸ガス好ましくはその温
度度での蒸気圧以上に加圧した炭酸ガスおよび超
臨界状態の炭酸ガスである。ここで、超臨界状態
とは、臨界点（CP）以上の圧力、温度の領域を
指す。
そして、このような液状または超臨界状態の炭
酸ガスに玄米や精米を接触させて、脱脂、脱臭、
脱糠を行う。具体的には、まず耐圧容器内に玄
米、精米を所定量収容する。次に上記状態の炭酸
ガスを加えて洗浄処理する。この際の炭酸ガスの
温度は−20〜＋150℃、圧力は20〜300Kg／cm2とさ
れる。また、外部から撹拌等の外力を加える必要
はないが、必要に応じて静かに撹拌してもよく、
さらには一定量の炭酸ガスを容器内に連続的に循
環させて洗浄するようにしてもよく。処理時間は
特に限定されるものではなく、数分〜数時間の範
囲で用途によつて適宜選択される。炭酸ガスの温
度、圧力は上記範囲から目的に応じて好ましい値
が選ばれる。すなわち、米中の臭気成分を主に除
去しようとする場合（脱臭）には低温、低圧で処
理すればよく、20〜80Kg／cm2、−20〜＋20℃の範
囲とされる。また、臭気成分と油脂分を同時に除
去しようとする場合（脱脂、脱臭）には高温、高
圧で処理すればよく、80〜300Kg／cm2＋20〜＋150
℃で処理すればよい。一般に、高温、高圧で処理
すれば炭酸ガスの溶剤としての溶解性が向上し、
よく脱脂、脱臭されるようになるが、温度が＋
150℃以上となると米のデンプンの変性を来し、
好ましくなく、圧力が300Kg／cm2以上となると耐
圧容器の耐圧および作業の安全性から不都合とな
る。
一定時間処理が行われたのち、まず炭酸ガスが
耐圧容器から排出され、ついで１秒当り約1.2
Kg／cm2以下の減圧速度で容器内の圧力を常圧まで
減じた後、玄米または精米を取り出す。この際、
急激な減圧は胴割れの原因となるので注意を要す
る。
以上の処理によつて、玄米、精米中の粗脂妨、
臭気成分が炭酸ガスによつて抽出され、炭酸ガス
に移行して除去されるとともに精米表面に付着し
ている糠も同時に除去される。したがつて、例え
ば酒造用原料米をこの方法によつて処理する場合
には精白度（精米歩合）は、最小限の91〜92％で
充分であり、原料米の歩留を向上させることがで
きる。また、処理中炭酸ガスが米粒内部まで浸透
するため、処理後の水の吸水速度および吸水率が
飛躍的に（未処理米に比して特に吸水速度が２〜
10倍）に増加する。よつて、酒造用原料米とした
ときの蒸しが良好となり、溶解糖化が促され、歩
留もよくなる。さらに、驚くべきことに高圧下に
よる処理にもかかわらず、米粒の胴割れや破砕等
の米粒の損傷が全く無く、外観の良好な処理米が
得られる。
このようにして洗浄処理を受けた米穀は脱脂、
脱臭が行わわれて、異臭がなく、、光沢に富み透
明感のある白色の米穀が得られ、清酒、ビール等
の醸造原料米として特に好適であるばかりでな
く、米飯としてあるいは各種米加工品の原料とし
て広く使用れうるものである。
また、炭酸ガスは周知のように食品衛生上安全
なものであり、全く無害であり、しかも処理中に
米穀中の害虫やこれらの卵等を死滅させることも
できる。
以下、実施例を示して、この発明を具体的に説
明する。
〔実施例〕
ササニシキ（昭和55年宮城県産）の精米（精白
度91％）１Kgを耐圧容器に入れ、25℃、85Kg／cm2
の炭酸ガス２Kgをこの容器内に連続して循環して
流し、洗浄処理した。３時間炭酸ガスを流しつづ
けたのち、炭酸ガスを容器から排出し、ついで処
理精米を取り出し、このものを試料として、粗脂
肪含量、吸水性を測定するとともに官能試験によ
つて外観および臭気を検査した。各試験法は以下
の通りである。
粗脂肪含量………試料を粉砕後、約10gを精秤
し、ソツクスレ−抽出装置でエチルエーテルを抽
出溶媒として抽出した。粗脂剖含量は以下の式を
用いて算出した。
粗脂肪含量（％）＝抽出油脂ｇ／試料ｇ×100
吸水性………重量既知のステンレス製管に試料
約10g精秤して入れ、これに15℃の水を加えて所
定時間浸漬した。その後、遠心分離機にかけて
3000rpm、５分間遠心分離して精米表面に付着し
ている水を除いて試料と管との重量を測定した。
吸水による重量増加分をagとすれば吸水率は次
式で求められる。なお、浸漬時間は10、20、30、
120分とした。
吸水率＝ａ（ｇ）／試料の重量ｇ×100
官能試験…６名のパネルにより、試料の外観を
目視により検討し、さらに試料を水洗せずに所定
時間水中に浸漬した後、40分間蒸きようし、その
臭気を検査した。
また、同様に炭酸ガスの温度、圧力、処理時
間、米穀品種、精白度を変化させて、洗浄処理を
行つた。処理条件、品種および結果を表および第
３図に示す。
The present invention relates to a washing treatment method for brown rice and polished rice, which is particularly suitable for obtaining raw rice for sake brewing. Requirements for raw rice for sake brewing include that it does not contain ingredients that give off-flavors or off-flavors to sake, that it is easy to steam, that the koji is well broken down, and that it dissolves and saccharifies well. It has been found that the causes of off-taste and odor are due to fats and oils (crude spinning), starch odor components, and old rice odor components contained in raw rice, and efforts are being made to reduce the content of these components in raw rice as much as possible. I'm being made to do it. In addition, in order to obtain steamed rice that is uniformly steamed and has good quality, the raw material rice must have good water absorption. The graph shown in Figure 1 shows the change in the crude fat content in milled rice depending on the rice polishing ratio. From this graph, it can be seen that when the rice polishing ratio reaches 75%, the crude fat content increases rapidly in proportion to this. However, it can be seen that the rate of decrease decreases significantly when it falls below 75%. Based on these results, raw rice is currently highly polished to a polishing ratio of 75 to 73%, reducing odor components and oil content, and meeting the above requirements.
However, if high-level polishing is performed, the raw material yield will naturally be extremely poor, leading to an increase in sake brewing costs.
Furthermore, during milling, raw rice often cracks and breaks, resulting in poor milled rice yield and a high degree of ineffective milling. Furthermore, a large amount of bran is generated during milling, and the processing of this sugar is also a major problem. On the other hand, rice is also used in large quantities as a raw material for beer brewing. In beer brewing as well, the oil and fat content of raw rice has a large effect on the quality of the beer product. In other words, if the oil content is high, the flavor of the beer will be severely impaired, the foam will not last long, and the filterability will be reduced.
Prolongs saccharification time and reduces extract yield. Therefore, the oil and fat content as raw material rice for beer is 1
% or less, and the whitening is done accordingly. In addition, before steaming the polished rice grains, it is necessary to remove the bran and bran odor adhering to the surface of the rice grains. This removal treatment is generally performed by washing with water. However, the method of washing with water requires a large amount of water when it is processed industrially, and has the disadvantage that the waste water causes pollution. In other words, the waste water after washing has a very high BOD and contains oil, so it requires a large amount of money to purify it. Another drawback is that active ingredients such as sugar and amino acids flow out when washed with water and cannot be recovered. This invention was made in view of the above circumstances,
The purpose of the present invention is to provide a rice processing method that can extremely efficiently defatte and deodorize rice used as raw material for sake brewing, does not cause damage such as cracking or crushing the rice, and does not require washing the rice with water. That is. This invention will be explained in detail below. The method for treating rice grains of the present invention involves bringing rice grains such as brown rice and polished rice into contact with carbon dioxide gas in a liquid or supercritical state. First, the properties of carbon dioxide gas, which is the extraction solvent used in this invention, will be explained. FIG. 2 shows a pressure-temperature diagram (PT-diagram) of carbon dioxide gas, and each state (liquid, solid, gas) of carbon dioxide gas is displayed depending on the temperature and pressure. TP in the diagram
indicates the temperature and pressure at which three phases coexist at the triple point,
CP is the pressure (Pc) at the critical point of 73.8 bar (72.84 Kg/
cm 2 ) and temperature (Tc) of 31.06°C. The carbon dioxide gas used in this invention is within the shaded range in Figure 2, preferably liquid carbon dioxide gas, carbon dioxide gas pressurized above the vapor pressure at that temperature, and carbon dioxide gas in a supercritical state. It is. Here, the supercritical state refers to a region of pressure and temperature above the critical point (CP). Then, brown rice or polished rice is brought into contact with such liquid or supercritical carbon dioxide gas to degrease, deodorize,
Remove the bran. Specifically, first, a predetermined amount of brown rice and polished rice is placed in a pressure container. Next, carbon dioxide gas in the above state is added for cleaning treatment. At this time, the temperature of the carbon dioxide gas is -20 to +150°C, and the pressure is 20 to 300 Kg/ cm2 . In addition, there is no need to apply external force such as stirring from the outside, but you may stir gently if necessary.
Furthermore, cleaning may be performed by continuously circulating a certain amount of carbon dioxide gas inside the container. The processing time is not particularly limited, and is appropriately selected depending on the application within the range of several minutes to several hours. Preferable values for the temperature and pressure of carbon dioxide gas are selected from the above ranges depending on the purpose. That is, when mainly removing odor components from rice (deodorization), it is sufficient to perform the treatment at low temperature and low pressure, and the range is 20 to 80 kg/cm 2 and -20 to +20°C. In addition, when attempting to remove odor components and fats and oils at the same time (degreasing, deodorization), it is sufficient to process at high temperature and pressure, 80 to 300Kg/cm 2 +20 to +150
It can be processed at ℃. Generally, treatment at high temperature and high pressure improves the solubility of carbon dioxide as a solvent.
It will be well degreased and deodorized, but if the temperature is +
If the temperature exceeds 150℃, the starch of rice will be denatured.
If the pressure exceeds 300 kg/cm 2 , it will be undesirable in terms of pressure resistance of the pressure container and work safety. After the treatment has been carried out for a certain period of time, carbon dioxide gas is first discharged from the pressure vessel, and then at a rate of approximately 1.2 per second.
After reducing the pressure inside the container to normal pressure at a decompression rate of Kg/ cm2 or less, take out the brown rice or polished rice. On this occasion,
Care must be taken as sudden decompression may cause the shell to crack. Through the above processing, brown rice, coarse fat during polishing,
Odor components are extracted by carbon dioxide gas, transferred to carbon dioxide gas, and removed, and the bran adhering to the surface of the milled rice is also removed at the same time. Therefore, for example, when raw rice for sake brewing is processed using this method, a minimum polishing rate (rice polishing ratio) of 91 to 92% is sufficient, and it is possible to improve the yield of raw rice. can. In addition, since carbon dioxide gas permeates into the inside of the rice grain during the treatment, the water absorption rate and water absorption rate of the treated water dramatically increase (compared to untreated rice, the water absorption rate is 2 to 30%).
10 times). Therefore, when the rice is used as a raw material for sake brewing, it can be steamed well, dissolution and saccharification is promoted, and the yield is also improved. Furthermore, surprisingly, despite the treatment under high pressure, there is no damage to the rice grains such as cracking or crushing of the rice grains, and treated rice with a good appearance can be obtained. The rice that has been washed in this way is defatted and
After deodorization, the resulting white rice is glossy and transparent, with no foreign odors, and is not only particularly suitable as a raw material for brewing sake, beer, etc., but also as rice or in various processed rice products. It can be widely used as a raw material. Furthermore, as is well known, carbon dioxide gas is safe from a food hygiene perspective, is completely harmless, and can also kill pests and their eggs in rice grains during processing. Hereinafter, the present invention will be specifically explained with reference to Examples. [Example] 1 kg of polished Sasanishiki rice (produced in Miyagi prefecture in 1980) (polishing degree 91%) was placed in a pressure container and heated to 85 kg/cm 2 at 25°C.
2 kg of carbon dioxide gas was continuously circulated into this container for cleaning treatment. After continuing to flow carbon dioxide gas for 3 hours, the carbon dioxide gas was discharged from the container, and the treated polished rice was then taken out and used as a sample to measure the crude fat content and water absorption, as well as to examine the appearance and odor through a sensory test. did. Each test method is as follows. Crude fat content: After pulverizing the sample, approximately 10 g was accurately weighed and extracted using a Soxhlet extractor using ethyl ether as an extraction solvent. The crude fat content was calculated using the following formula. Crude fat content (%) = Extracted oil g/Sample g x 100 Water absorption: Approximately 10 g of the sample was accurately weighed and placed in a stainless steel tube of known weight, and 15°C water was added thereto and immersed for a predetermined time. Then put it in a centrifuge
The sample was centrifuged at 3000 rpm for 5 minutes to remove water adhering to the surface of the polished rice, and the weight of the sample and tube was measured.
If the weight increase due to water absorption is ag, the water absorption rate can be calculated using the following formula. The soaking time is 10, 20, 30,
It was set as 120 minutes. Water absorption rate = a (g) / weight of sample g x 100 Sensory test: The appearance of the sample was visually examined by a panel of six people, and the sample was immersed in water for a predetermined time without washing, and then steamed for 40 minutes. I then tested the odor. In addition, the cleaning treatment was performed by changing the carbon dioxide temperature, pressure, treatment time, rice grain variety, and polishing degree in the same manner. The treatment conditions, varieties and results are shown in the table and FIG.
【表】【table】
【表】
表および第３図の結果から明らかなように、処
理によて、粗脂肪含量が低下し、脱脂が効果的に
行われ、糠臭も全くなく臭気成分の除去も完全に
行われている。また、外観も白色、透明感に富
み、非常に好ましいものとなり、しかも胴割れ、
破砕もない。さらに処理によつて米の吸水速度が
大きく増大し、吸水率も向上することがわかる。
以上説明したように、この発明の米穀の処理方
法は、米穀を液状または超臨界状態の炭酸ガスに
接触させて処理し、炭酸ガスの溶解能によつて米
穀中の粗脂肪、異臭成分および糠を除去するもの
であるので、処理された米穀は、粗脂肪含量が低
下し、異臭成分も存在せず、かつ外観も美麗で吸
水性が向上し、特に醸造用原料米として好適なも
のとなる。また、蒸きように際し、水洗の必要が
ないので、洗米廃水による公害等の問題も生じ
ず、洗浄に伴う省力化も達成できる。さらに炭酸
ガスは食品衛生上全く無害であり、この処理によ
る食品衛生上の問題を招くこともない。特にま
た、清酒用原料米としては従来のように高度に精
白する必要がなく、原料歩留が大幅に向上すると
ともに洗米工程の不要化廃水処理の不要化が達成
され、清酒製造コストの大幅な低減が計れる。さ
らに、処理によつて米穀中の害虫やこれらの卵等
を死滅させることができるとともに乾燥状態で米
穀を回収できるので保存が容易で長時間の保存が
可能である。また、炭酸ガスから除去された脂
肪、糠等を容易に乾燥状態で回収できるのでこれ
らの有効利用をも計るとができる。さらにまた、
炭酸ガスは安価に入手できるとともに循環して使
用することにより、消費量が少くて済み、処理費
用も安くて済むなどのすぐれた利点を有する。[Table] As is clear from the results in the table and Figure 3, the treatment reduced the crude fat content, effectively degreased the oil, and completely removed odor components without any bran odor. ing. In addition, the appearance is white and transparent, making it very desirable.
No crushing. Furthermore, it can be seen that the water absorption rate of the rice increases significantly through the treatment, and the water absorption rate also improves. As explained above, the rice grain processing method of the present invention involves treating rice grains by bringing them into contact with carbon dioxide gas in a liquid or supercritical state. As a result, the treated rice has a lower crude fat content, no off-flavor components, a beautiful appearance, and improved water absorption, making it particularly suitable as raw material rice for brewing. . Furthermore, since there is no need for washing with water during steaming, problems such as pollution caused by waste water from washing rice do not occur, and labor savings associated with washing can also be achieved. Furthermore, carbon dioxide gas is completely harmless in terms of food hygiene, and this treatment does not pose any food hygiene problems. In particular, rice used as a raw material for sake does not need to be polished to a high degree as in the past, which greatly improves the raw material yield, eliminates the need for a rice washing process, and eliminates the need for wastewater treatment, resulting in a significant reduction in sake production costs. The reduction can be measured. Furthermore, the treatment can kill pests and their eggs in the rice grains, and the rice grains can be collected in a dry state, making it easy to store and can be stored for a long time. Furthermore, since fat, bran, etc. removed from carbon dioxide gas can be easily recovered in a dry state, they can be used effectively. Furthermore,
Carbon dioxide gas has excellent advantages such as being available at a low cost, and by using it in a circular manner, the consumption amount is small and the processing cost is low.
【図面の簡単な説明】[Brief explanation of the drawing]
第１図は米穀の精米歩合と脂質含量との関係を
示すグラフ、第２図は炭酸ガスの圧力一温度線
図、第３図は本発明の処理方法によつて得られた
米穀の吸水性を示すグラフである。
Figure 1 is a graph showing the relationship between rice milling ratio and lipid content, Figure 2 is a carbon dioxide pressure-temperature diagram, and Figure 3 is the water absorption of rice obtained by the treatment method of the present invention. This is a graph showing.