JP3918693B2

JP3918693B2 - Cooked rice incubator

Info

Publication number: JP3918693B2
Application number: JP2002269556A
Authority: JP
Inventors: 孝裕梅田; 祐福田; 章広梅田; 彪長井
Original assignee: Panasonic Corp; Matsushita Electric Industrial Co Ltd
Current assignee: Panasonic Corp; Panasonic Holdings Corp
Priority date: 2002-09-17
Filing date: 2002-09-17
Publication date: 2007-05-23
Anticipated expiration: 2022-09-17
Also published as: JP2004105333A

Description

【０００１】
【発明の属する技術分野】
本発明は、米飯の黄変化や食味の際の物性低下を抑制し、保温してもおいしい米飯が得られる米飯保温器に関するものである。
【０００２】
【従来の技術】
従来、この種の米飯保温器としては、内釜（炊飯釜）の空気を減圧する減圧装置と、空気中の酸素のみを通過させる気体分離膜とを備えたものが知られている（例えば特許文献１参照）。
【０００３】
これは、減圧装置の前段に空気中の酸素のみを通過させる気体分離膜を備え、減圧装置を動作させることにより、内釜内の空気を、気体分離膜を通して外部に排出させ、内釜内の酸素の絶対量を減少させるものである。これにより、保温中の米飯の黄変化や保温臭の発生を防止していた。
【０００４】
【特許文献１】
特開平５−１５４０３９号公報
【０００５】
【発明が解決しようとする課題】
しかしながら、前記従来の米飯保温器では、内釜内の空気を減圧装置で排出させる構成であり、内釜内は高度な密閉性が要求され、また、長時間高度な密閉性を維持することは難しく、一般家庭用として適しているとは言い難い。
【０００６】
本発明は、前記従来の課題を解決するもので、窒素富化な空気と水蒸気により、米飯の黄変化や食味の際の物性低下を抑制し、保温してもおいしい米飯が得られる米飯保温器を提供することを目的とする。
【０００７】
【課題を解決するための手段】
前記目的を達成するために、本発明の米飯保温器は、大気中に含まれる酸素を除去し窒素富化なガスを供給する窒素供給手段と、内釜に水蒸気を供給する水蒸気供給手段と、内釜内への窒素供給および水蒸気供給を制御する制御手段とを備えたものである。
【０００８】
これにより、窒素富化な空気と水蒸気により、米飯の黄変化や食味の際の物性低下を抑制し、保温してもおいしい米飯が得られる。
【０００９】
【発明の実施の形態】
請求項１に記載の発明は、米飯を収容する内釜と、前記内釜の上方に設けた開閉可能な蓋と、前記内釜の米飯を加熱する加熱手段と、前記内釜の温度を検出する温度検出手段と、大気中に含まれる酸素を除去し窒素富化なガスを内釜へ供給する窒素供給手段と、窒素富化なガスを運搬するガス輸送手段と、予め水を貯蔵する水貯蔵手段と、前記水貯蔵手段を加熱する水加熱手段からなる前記内釜に水蒸気を供給する水蒸気供給手段と、前記温度検出手段の検出値をもとに前記加熱手段を用いて前記米飯を所定温度に加熱制御するとともに、前記窒素供給手段から内釜への窒素供給および水蒸気供給手段から内釜への水蒸気供給を制御する制御手段とを備えた米飯保温器としたことにより、内釜内へ窒素富化な空気と水蒸気の供給で、米飯の黄変化や食味の際の物性低下を抑制し、保温してもおいしい米飯が得られる。
【００１０】
また、一定時間毎に供給する水蒸気量に応じ、水加熱手段で水貯蔵手段を加熱するように制御し、内釜内に水蒸気を供給することができるので、米飯の黄変化や食味の際の物性低下を効果的に抑制することができ、保温してもおいしい米飯が得られる。
【００１１】
【実施例】
以下、本発明の実施例について、図面を参照しながら説明する。
【００１２】
図１は、本発明の実施例における米飯保温器を組み込んだジャー炊飯器を示すものである。図において、１は本体２内に装備した内釜であり、所定量の米飯と水とを収容して加熱調理を行う。
【００１３】
内釜１の底には、内釜１の温度を検出する温度検出手段４が内釜１に接するように設けられており、また、内釜１を加熱する電磁誘導の加熱コイルからなる加熱手段５が設けられている。６は温度検出手段４の検出値をもとに加熱手段５を用いて米飯を所定温度に加熱制御するとともに、窒素供給手段（後記）から内釜１への窒素富化なガスの供給量を制御する制御手段であり、加熱手段５に電力を供給する高周波電源も備えている。７は内釜１の側部の上部に設けた保温用の加熱手段である。８は内釜１の上方に設けた開閉可能な蓋で、その下部の放熱板９には、蓋用の加熱手段１０、および内釜１の温度を検出する蓋用の温度検出手段１１が設けられている。前記加熱手段７は制御手段６により加熱制御され、温度検出手段１１による検出値は制御手段６に入力されるものである。
【００１４】
また、蓋８には大気中に含まれる酸素を除去し窒素富化なガスを供給する窒素供給手段１５と、ガスを運搬するポンプやファンなどから成るガス輸送手段１６が設けられており、窒素供給手段１５と内釜１の間には前記内釜に水蒸気を供給する水蒸気供給手段１７が設けられている。
【００１５】
水蒸気供給手段１７は、予め水を貯蔵する水貯蔵手段１７ａと、この水貯蔵手段１７ａを加熱する水加熱手段１７ｂとを備えている。水貯蔵手段１７ａには、外部より水を供給する栓付きの給水口１７ｃと、水貯蔵手段１７ａから水を排出する栓付きの排水口１７ｄと、放熱板９を通して内釜１内に臨む蒸気口１７ｅとが設けられている。
【００１６】
また、窒素供給手段１５と水蒸気供給手段１７とは、窒素供給手段１５から延びたパイプ１５ａの先端を水貯蔵手段１７ａ内の水中に位置させて連絡している。そして、窒素供給手段１５からパイプ１５ａへの連絡部分にはバルブ１８が設けてある。
【００１７】
上記窒素供給手段１５と、ガス輸送手段１６および水蒸気供給手段１７の構成において、ガス輸送手段１６の動作によって、内釜１内の高濃度の酸素を含むガスを排出する（矢印ａ）ことにより、外部空気は、開口を介して窒素供給手段１５へと導かれ（矢印ｂ）、窒素供給手段１５で窒素と酸素に分離され、酸素は窒素供給手段１５を介して再び開口より外部へ放出される（矢印ｃ）。
【００１８】
一方、分離された窒素は、再び大気と混合され窒素富化なガスとなり、水蒸気供給手段１７を介して内釜１内へと導かれ（矢印ｄ）、内釜１内は速やかに窒素富化なガスに置換される。
【００１９】
一方、制御手段６が、窒素供給手段１５と、水加熱手段１７ｂと、バルブ１８およびガス輸送手段１６をコントロールすることにより、水蒸気供給手段１７から、水蒸気を内釜１内に連続供給、あるいは一定時間毎に供給を繰り返す間欠供給が行われる。水蒸気の供給は、窒素富化なガスと同時あるいは個別に行うものである。窒素富化なガスと水蒸気により、内釜１内の保温臭気を飛散させ、米飯の黄変化や食味の際の物性低下を抑制し、長時間、蓋８を密閉していても、おいしい米飯を提供することができる。
【００２０】
なお、内釜１内のガスを大気へと排出する、ガス輸送手段１６を設けた開口は、炊飯時には蒸気抜きとしても働くものである。また、内釜１から窒素供給手段１５へ高濃度の酸素を含むガスが逆流しないように蒸気口１７ｅには逆止弁が設けられている。
【００２１】
また、蓋８の上部の操作パネル部には、内釜１内の酸素濃度を表示する表示手段１２が設けられ、蓋８と本体２との接触部には、蓋開閉を検知する開閉検知手段１９を備えている。この開閉検知手段１９はリードスイッチのようなもので構成されており、開閉検知手段１９の情報より蓋８の開閉状態を制御手段６で検知している。なお、この図では電源線や信号線などの結線は省略されている。
【００２２】
この米飯保温器では、炊飯後、保温中の米飯の温度を内釜１の底に接する温度検出手段４で検知する。この情報は制御手段６に送られ、米飯の温度が保温設定温度である７２℃となるように加熱手段５に電力を供給して磁力を発生させ、ステンレスとアルミニウムから成るクラッド材で構成された内釜１のステンレス層を電磁誘導により加熱し、米飯を保温する。また、加熱手段７、１０の入力を制御手段６が電子制御することにより、米飯の量に応じた加熱熱量を与え、保温設定温度７２℃に米飯温度を保つようになっている。
【００２３】
さらに、制御手段６は、内釜１への窒素富化なガスおよび水蒸気の供給を制御することは先に記述したとおりである。
【００２４】
次に、窒素供給手段１５について、図２を基に説明する。これは、酸素イオン導電性を有する固体電解質２０と、前記固体電解質２０の互いに異なる表面に形成された一対の電極２１、２２と、前記一対の電極２１、２２間に接続された電圧供給装置２３と、前記固体電解質２０を加熱するヒータ２４と、前記ヒータ２４に電圧を供給するヒータ電源２５と、前記固体電解質２０および前記ヒータ２４の周囲に設けられた断熱材２６とを備えており、外部空気中に含まれる酸素を除去して外部に排出し、残りの窒素富化なガスを内釜１に供給するものである。前記固体電解質２０と一対の電極２１、２２とで酸素ポンプを構成している。この酸素ポンプの電圧−電流特性を図３に示している。
【００２５】
また、断熱材２６は、ヒータ２４で固体電解質２０を効率よく加熱するために設けられているもので、ヒータ２４は断熱材２６に埋設され、一体で形成され、窒素供給手段１５の小型化をはかっている。
【００２６】
また、断熱材２６は、多孔性であり通気性を有するので、ガスは十分に流出入し、外部と一対の電極２１、２２の間で酸素の授受が滞ることなく行われ、効率よく窒素富化なガスを供給することができる。
【００２７】
また、一対の電極２１、２２の形成された互いに異なる空間を気密よく分離するためにシール材２７を有し、固体電解質２０を気密よく断熱材２６および金属製の筐体に固定し、一方の電極２１（カソード）で分離した窒素富化の空気と、もう一方の電極２２（アノード）から放出される酸素を混合することなく分離しており、効率よく窒素富化なガスを供給することができるようにしている。
【００２８】
固体電解質２０には酸素イオン導電性を有するランタンガリウム酸化物から成る直径約２０ｍｍ厚さ１ｍｍのディスクを用い、この両面に一対の電極２１、２２としてペロブスカイト酸化物から成るペーストを印刷し、乾燥後、さらにその上に集電体を積層し、金属箔からなるシール材２７と、リード線を取り付け電気炉で焼成した。固体電解質２０には他の酸素イオン導電性を有する安定化ジルコニア、安定化セリアなども使用することができ、実施例で用いたランタンガリウム酸化物の酸素イオン導電性を向上させるためにランタンサイトおよびガリウムサイトの一部に遷移金属やアルカリ土類金属など異種金属を置換してもよい。
【００２９】
また、電圧供給装置２３と、固体電解質２０の間に固体電解質２０に流れる電流を検出する電流検出手段２８を接続した。落下や、耐久劣化などの原因により固体電解質２０、一対の電極２１、２２あるいはヒータ２４が劣化した場合、固体電解質２０に流れる電流に変化が現れるため、電流検出手段２８の検出値をもとに制御手段６が、窒素供給手段１５の状態を自己診断し、電流検出手段２８の検出値が予め設定した閾値を越えた場合、おいしい米飯を提供できる期間を判定し、窒素供給手段１５の交換を促したり、寿命を報知させたりすることができる。
【００３０】
また、米飯を保温した状態において開閉検知手段１９で蓋８が開から閉となったことを検知してからの経過時間と、電流検出手段２８の検出値をもとに内釜１内の酸素濃度を算出し、操作パネル部上の表示手段１２に酸素濃度を表示させる。したがって、内釜１内の酸素濃度を可視化でき、使用者が現在の内釜１内の酸素濃度を知ることができるだけでなく、米飯のおいしさを可視化することもできるので、おいしく米飯を食べられる期間を報知することができる。
【００３１】
ここで、外部より取り込まれ窒素供給手段１５に供給された大気は、多孔質な断熱材２６を介し、一方の電極２１（カソード）に到達し、大気に含まれる酸素がカソード２１上に吸着する。そして、電圧供給装置２３により一対の電極２１、２２間に電圧が与えられると、吸着した酸素は電子を受け取り、電極２１と固体電解質２０と気相との間に形成される三相界面より固体電解質２０中へ取り込まれ、酸素イオンとなり固体電解質２０中を移動する。
【００３２】
もう一方の電極２２（アノード）に到達した酸素イオンは、電極２２と固体電解質２０と気相との間に形成される三相界面で電子を放ち、再び酸素となり大気へ排出される。酸素が除去された窒素富化なガスは、ガス輸送手段１６の動作により、内釜１に供給され、高濃度な酸素を含むガスと置換され、高濃度な酸素を含むガスは外部へと排出される。その結果、内釜１内は低酸素濃度となり、米飯中の脂質、タンパク質および炭水化物が空気中の酸素と酸化反応したり、これらの物質が分解あるいは重合反応したりすることが抑制され、米飯の黄変化、保温臭の発生を低減することができる。
【００３３】
また、細菌の活性を抑えることができ、米飯の腐敗を遅延させることができる。また、細菌の活性を抑えることができ、米飯の腐敗を遅延させることができる。
【００３４】
上記のように構成された米飯保温器を用いて米飯の保温状態について調べた。まず、内釜１内に米飯の原料である米と水を入れ、炊飯を行った。炊飯直後、内釜１内のガスの酸素濃度はほぼ０％であったが、内部が冷えて飽和蒸気圧が下がるとともに外部から空気が流入し、徐々に酸素濃度は上昇した。
【００３５】
そこで、窒素供給手段１５のヒータ２４にヒータ電源２５を用いて１０〜２０Ｗの電力を供給し、固体電解質２０および一対の電極２１、２２で構成される酸素ポンプの動作温度が６００〜７００℃になるように加熱した。そして、一対の電極２１、２２間に電圧供給装置２３で所定の電圧を供給し、さらにガス輸送手段１６を作動させ、水蒸気供給手段１７を介して内釜１内に窒素富化なガスと水蒸気を供給した。窒素供給量は、電圧供給装置２３およびガス輸送手段１６を制御手段６により制御することで変化させることができる。
【００３６】
図４は、窒素供給手段１５で内釜１内の空気を窒素富化なガスに置換したときの保温時間と内釜１内の酸素濃度の関係を示した。酸素ポンプにより分離された酸素は毎分１０〜３０ｃｃで外部へ排出され、分離された窒素は再び空気と混合され、窒素富化なガスとなり、連続して毎分４０〜１２０ｃｃで内釜１内に供給される。これにより、内釜１内の空気は速やかに窒素富化なガスに置換され、２０〜６０分で内釜１内の酸素濃度は２〜４％となったので、窒素供給量を減らし、そのまま保持した。しばらくして外部空気の流入により内釜１内の酸素濃度が増加したが、ある程度、低濃度の段階で再び窒素供給量を増加することにより、迅速に内釜１内の酸素濃度を低下させることができた。また、このとき内釜１の内部はほぼ大気圧であり、気密構成も簡単でよいことが判った。
【００３７】
次に、炊飯直後、内釜１内の酸素濃度を２〜４％に保持し、水蒸気供給手段１７により水蒸気を供給したときの官能評価を行った。大気で保持した場合は、米飯の酸化がわずかに起こっており、保温臭と食味の評価が低かったのに対して、低酸素濃度で保持し水蒸気を供給した場合は、保温臭も少なく、食味もよかった。
【００３８】
さらに、この状態で１２時間および２４時間保温した米飯の官能評価を行ったところ、いずれも保温臭が少なく、炊き立ての匂いを有しており、黄変化も少なく、食味評価も粘り、弾力性など優れており、総合評価が高かった。これに対して、大気中で１２時間および２４時間保温した米飯は、いずれも保温臭がきつく、黄変化が発生しており、乾燥して食味もまずく、総合評価が低かった。
【００３９】
次に、蓋８を開閉させた場合の米飯の保温状態について調べた。蓋８を開けた直後は、内釜１内の酸素濃度は大気中の酸素濃度と等しくなり２０．８％となった。蓋８を閉めると開閉検知手段１９が、蓋８が閉まったことを検知し、窒素供給手段１５と、水蒸気供給手段１７と、バルブ１８およびガス輸送手段１６が動作する。内釜１内の空気は窒素富化なガスに速やかに置換され、２０〜６０分で内釜１内の酸素濃度は２〜４％となったので、窒素供給量を減らし、そのまま保持した。しばらくして外部空気の流入により内釜１内の酸素濃度が増加したが、ある程度、低濃度の段階で再び窒素供給量を増加することにより、迅速に内釜１内の酸素濃度を低下させることができた。
【００４０】
また、保温した状態において開閉検知手段１９で蓋８が開から閉となったことを検知したとき、水加熱手段１７ｂの出力を制御することにより、供給する水蒸気量を多くしたり、一定時間後に供給する水蒸気量を減らしたりするので、蓋８の開閉により内釜１内の水蒸気濃度が減少しても、米飯に水蒸気を供給することができ、保温中の米飯の保温臭気や黄変化を防ぎ、食味の低下を防止することができる。
【００４１】
蓋８を開閉した場合の米飯の官能評価も保温臭、米飯の黄変化および食味の物性など総合的によい結果が得られた。
【００４２】
また、保温する米飯の量に応じて窒素富化なガスおよび水蒸気の供給量を変化させることにより、保温臭の少ないおいしい米飯を提供できることが判った。
【００４３】
【発明の効果】
以上のように、本発明の米飯保温器によれば、大気中に含まれる酸素を除去し窒素富化なガスを供給する窒素供給手段と、内釜に水蒸気を供給する水蒸気供給手段と、内釜内への窒素供給および水蒸気供給を制御する制御手段とを備えたもので、窒素富化な空気と水蒸気により、米飯の黄変化や食味の際の物性低下を抑制し、保温してもおいしい米飯が得られる。
【図面の簡単な説明】
【図１】本発明の実施例における米飯保温器の概略構成を示す断面図
【図２】同米飯保温器の窒素供給手段の断面図
【図３】同窒素供給手段の電圧ー電流の特性図
【図４】同米飯保温器の保温時間と酸素濃度の関係を示す特性図
【符号の説明】
１内釜
４、１１温度検出手段
５、７、１０加熱手段
６制御手段
８蓋
１５窒素供給手段
１６ガス輸送手段
１７水蒸気供給手段
１７ａ水貯蔵手段
１７ｂ水加熱手段
１９開閉検知手段
２０固体電解質
２１、２２一対の電極
２３電圧供給装置
２４ヒータ
２５ヒータ電源
２６断熱材
２７シール材
２８電流検出手段[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a cooked rice warmer that suppresses yellowing of cooked rice and deterioration of physical properties during eating, and can provide delicious cooked rice even when kept warm.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, as this kind of cooked rice incubator, one having a decompression device that decompresses air in an inner pot (rice cooker) and a gas separation membrane that allows only oxygen in the air to pass through is known (for example, a patent) Reference 1).
[0003]
This is provided with a gas separation membrane that allows only oxygen in the air to pass through at the front stage of the decompression device, and by operating the decompression device, the air in the inner pot is exhausted to the outside through the gas separation membrane. It reduces the absolute amount of oxygen. As a result, yellowing of the cooked rice during the heat insulation and the generation of the heat insulation odor were prevented.
[0004]
[Patent Document 1]
Japanese Patent Laid-Open No. 5-154039
[Problems to be solved by the invention]
However, the conventional cooked rice warmer has a configuration in which the air in the inner pot is discharged by the decompression device, and the inner pot is required to have a high degree of hermeticity, and the high degree of hermeticity can be maintained for a long time. It is difficult to say that it is suitable for general household use.
[0006]
The present invention solves the above-mentioned conventional problems, and by using nitrogen-enriched air and water vapor, the cooked rice incubator can suppress the yellowing of the cooked rice and the deterioration of the physical properties during the taste and can obtain a delicious cooked rice even when kept warm. The purpose is to provide.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the cooked rice warmer of the present invention includes a nitrogen supply means for removing oxygen contained in the atmosphere and supplying a nitrogen-enriched gas, a steam supply means for supplying water vapor to the inner pot, And a control means for controlling supply of nitrogen and water vapor into the inner pot.
[0008]
Thereby, the nitrogen-enriched air and water vapor suppress yellowing of the cooked rice and deterioration of physical properties during eating, and a delicious cooked rice can be obtained even when kept warm.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
The invention according to claim 1 is an inner pot for storing cooked rice, an openable / closable lid provided above the inner pot, a heating means for heating the cooked rice in the inner pot, and detecting the temperature of the inner pot. Temperature detecting means, nitrogen supply means for removing oxygen contained in the atmosphere and supplying nitrogen-enriched gas to the inner kettle, gas transporting means for transporting nitrogen-enriched gas, and water for storing water in advance A steam supply means for supplying steam to the inner pot comprising a storage means, a water heating means for heating the water storage means, and the cooked rice using the heating means based on the detection value of the temperature detection means. In addition to controlling the heating to the temperature, the rice cooker is provided with a control means for controlling the supply of nitrogen from the nitrogen supply means to the inner pot and the supply of water vapor from the steam supply means to the inner pot. The supply of nitrogen-enriched air and water vapor makes yellow rice Suppressing property decrease during reduction and taste delicious rice can be obtained by incubating.
[0010]
In addition, according to the amount of water vapor supplied at regular intervals, the water storage means is controlled to be heated by the water heating means, and water vapor can be supplied into the inner pot. Degradation of physical properties can be effectively suppressed, and delicious cooked rice can be obtained even when kept warm.
[0011]
【Example】
Embodiments of the present invention will be described below with reference to the drawings.
[0012]
FIG. 1 shows a jar rice cooker incorporating a rice cooker in an embodiment of the present invention. In the figure, reference numeral 1 denotes an inner pot installed in the main body 2, which heats and cooks a predetermined amount of cooked rice and water.
[0013]
A temperature detecting means 4 for detecting the temperature of the inner hook 1 is provided at the bottom of the inner hook 1 so as to be in contact with the inner hook 1, and a heating means comprising an electromagnetic induction heating coil for heating the inner hook 1. 5 is provided. 6 controls the heating of the cooked rice to a predetermined temperature using the heating means 5 based on the detection value of the temperature detection means 4 and the supply amount of nitrogen-enriched gas from the nitrogen supply means (described later) to the inner pot 1. It is a control means for controlling, and is also provided with a high frequency power source for supplying power to the heating means 5. Reference numeral 7 denotes a heating means for heat insulation provided at the upper part of the side portion of the inner pot 1. Reference numeral 8 denotes an openable / closable lid provided above the inner hook 1, and the lower heat sink 9 is provided with a heating means 10 for the lid and a temperature detecting means 11 for the lid for detecting the temperature of the inner hook 1. It has been. The heating means 7 is heated and controlled by the control means 6, and the value detected by the temperature detection means 11 is input to the control means 6.
[0014]
Further, the lid 8 is provided with a nitrogen supply means 15 for removing oxygen contained in the atmosphere and supplying a nitrogen-enriched gas, and a gas transport means 16 comprising a pump and a fan for carrying the gas. Between the supply means 15 and the inner pot 1 is provided a water vapor supply means 17 for supplying water vapor to the inner pot.
[0015]
The water vapor supply unit 17 includes a water storage unit 17a that stores water in advance and a water heating unit 17b that heats the water storage unit 17a. The water storage means 17a includes a water supply port 17c with a plug for supplying water from the outside, a drainage port 17d with a plug for discharging water from the water storage means 17a, and a steam port facing the inner pot 1 through the radiator plate 9. 17e.
[0016]
Further, the nitrogen supply means 15 and the water vapor supply means 17 communicate with each other by positioning the tip of a pipe 15a extending from the nitrogen supply means 15 in the water in the water storage means 17a. A valve 18 is provided at a communication portion from the nitrogen supply means 15 to the pipe 15a.
[0017]
In the configuration of the nitrogen supply means 15, the gas transport means 16, and the water vapor supply means 17, by discharging the gas containing high concentration oxygen in the inner pot 1 by the operation of the gas transport means 16 (arrow a), The external air is led to the nitrogen supply means 15 through the opening (arrow b), and is separated into nitrogen and oxygen by the nitrogen supply means 15, and oxygen is again released to the outside through the nitrogen supply means 15. (Arrow c).
[0018]
On the other hand, the separated nitrogen is again mixed with the atmosphere to become a nitrogen-enriched gas, which is led into the inner pot 1 through the water vapor supply means 17 (arrow d), and the inner pot 1 is quickly enriched with nitrogen. The gas is replaced.
[0019]
On the other hand, the control means 6 controls the nitrogen supply means 15, the water heating means 17 b, the valve 18, and the gas transport means 16, so that water vapor is continuously supplied from the water vapor supply means 17 into the inner pot 1 or constant. Intermittent supply is performed that repeats supply every hour. The supply of water vapor is performed simultaneously or separately with the nitrogen-enriched gas. Nitrogen-enriched gas and water vapor dissipate the warming odor in the inner pot 1 and suppress the yellowing of the cooked rice and the deterioration of its physical properties when eating. Even if the lid 8 is sealed for a long time, Can be provided.
[0020]
In addition, the opening provided with the gas transport means 16 that discharges the gas in the inner pot 1 to the atmosphere also functions as a steam vent during rice cooking. Further, a check valve is provided at the steam port 17e so that a gas containing high-concentration oxygen does not flow backward from the inner pot 1 to the nitrogen supply means 15.
[0021]
In addition, a display means 12 for displaying the oxygen concentration in the inner pot 1 is provided in the operation panel section at the upper part of the lid 8, and an opening / closing detection means for detecting opening / closing of the lid is provided at the contact portion between the lid 8 and the main body 2. 19 is provided. The open / close detection means 19 is configured as a reed switch, and the control means 6 detects the open / closed state of the lid 8 based on information from the open / close detection means 19. In this figure, connections such as power lines and signal lines are omitted.
[0022]
In this cooked rice warmer, after cooking, the temperature of the cooked rice is detected by the temperature detecting means 4 in contact with the bottom of the inner pot 1. This information is sent to the control means 6, and the heating means 5 is supplied with electric power to generate a magnetic force so that the temperature of the cooked rice becomes 72 ° C., which is the heat retention set temperature, and is composed of a clad material made of stainless steel and aluminum. The stainless steel layer of the inner pot 1 is heated by electromagnetic induction to keep the cooked rice warm. Moreover, the control means 6 controls the input of the heating means 7 and 10 electronically, thereby giving a heating heat amount corresponding to the amount of cooked rice, and keeping the cooked rice temperature at the heat retention set temperature 72 ° C.
[0023]
Furthermore, the control means 6 controls the supply of the nitrogen-enriched gas and water vapor to the inner pot 1 as described above.
[0024]
Next, the nitrogen supply means 15 is demonstrated based on FIG. This includes a solid electrolyte 20 having oxygen ion conductivity, a pair of electrodes 21 and 22 formed on different surfaces of the solid electrolyte 20, and a voltage supply device 23 connected between the pair of electrodes 21 and 22. A heater 24 for heating the solid electrolyte 20, a heater power supply 25 for supplying a voltage to the heater 24, and a heat insulating material 26 provided around the solid electrolyte 20 and the heater 24, Oxygen contained in the air is removed and discharged to the outside, and the remaining nitrogen-enriched gas is supplied to the inner pot 1. The solid electrolyte 20 and the pair of electrodes 21 and 22 constitute an oxygen pump. The voltage-current characteristics of this oxygen pump are shown in FIG.
[0025]
The heat insulating material 26 is provided to efficiently heat the solid electrolyte 20 with the heater 24, and the heater 24 is embedded in the heat insulating material 26 and formed integrally to reduce the size of the nitrogen supply means 15. It's striking.
[0026]
Further, since the heat insulating material 26 is porous and has air permeability, the gas can flow in and out sufficiently, and oxygen can be exchanged between the outside and the pair of electrodes 21 and 22 without delay, and the nitrogen-rich material can be efficiently enriched. Gas can be supplied.
[0027]
In addition, a sealing material 27 is provided for airtightly separating different spaces in which the pair of electrodes 21 and 22 are formed, and the solid electrolyte 20 is airtightly fixed to the heat insulating material 26 and a metal housing, The nitrogen-enriched air separated at the electrode 21 (cathode) and the oxygen released from the other electrode 22 (anode) are separated without mixing, and an efficient nitrogen-enriched gas can be supplied. I can do it.
[0028]
As the solid electrolyte 20, a disk made of lanthanum gallium oxide having oxygen ion conductivity and having a diameter of about 20 mm and a thickness of 1 mm was used. A paste made of perovskite oxide was printed on both sides as a pair of electrodes 21 and 22 and dried. Further, a current collector was laminated thereon, and a sealing material 27 made of metal foil and lead wires were attached and fired in an electric furnace. The solid electrolyte 20 can also use other stabilized zirconia having stabilized oxygen ion conductivity, stabilized ceria, and the like. In order to improve the oxygen ion conductivity of the lanthanum gallium oxide used in the examples, A part of the gallium site may be substituted with a different metal such as a transition metal or an alkaline earth metal.
[0029]
Further, a current detection means 28 for detecting a current flowing through the solid electrolyte 20 is connected between the voltage supply device 23 and the solid electrolyte 20. When the solid electrolyte 20, the pair of electrodes 21, 22 or the heater 24 deteriorates due to a drop or deterioration of durability, a change appears in the current flowing through the solid electrolyte 20. Therefore, based on the detection value of the current detection means 28. When the control means 6 self-diagnose the state of the nitrogen supply means 15 and the detection value of the current detection means 28 exceeds a preset threshold value, it determines a period during which delicious cooked rice can be provided and replaces the nitrogen supply means 15. You can prompt or let you know the life.
[0030]
Further, in the state where the cooked rice is kept warm, the oxygen in the inner pot 1 based on the elapsed time after the opening / closing detection means 19 detects that the lid 8 has been opened and closed and the detection value of the current detection means 28. The concentration is calculated, and the oxygen concentration is displayed on the display means 12 on the operation panel unit. Therefore, the oxygen concentration in the inner pot 1 can be visualized and the user can not only know the current oxygen concentration in the inner pot 1 but also the deliciousness of the cooked rice, so that the user can eat delicious rice. The period can be notified.
[0031]
Here, the atmosphere taken in from the outside and supplied to the nitrogen supply means 15 reaches one electrode 21 (cathode) via the porous heat insulating material 26, and oxygen contained in the atmosphere is adsorbed on the cathode 21. . When a voltage is applied between the pair of electrodes 21 and 22 by the voltage supply device 23, the adsorbed oxygen receives electrons and is solid from a three-phase interface formed between the electrode 21, the solid electrolyte 20, and the gas phase. It is taken into the electrolyte 20 and becomes oxygen ions and moves through the solid electrolyte 20.
[0032]
The oxygen ions that have reached the other electrode 22 (anode) emit electrons at the three-phase interface formed between the electrode 22, the solid electrolyte 20, and the gas phase, and become oxygen again and discharged to the atmosphere. The nitrogen-enriched gas from which oxygen has been removed is supplied to the inner pot 1 by the operation of the gas transport means 16 and is replaced with a gas containing high-concentration oxygen, and the gas containing high-concentration oxygen is discharged to the outside. Is done. As a result, the inner pot 1 has a low oxygen concentration, and it is suppressed that lipids, proteins and carbohydrates in the cooked rice are oxidized with oxygen in the air, and these substances are not decomposed or polymerized. The occurrence of yellowing and warming odor can be reduced.
[0033]
Moreover, the activity of bacteria can be suppressed and the decay of cooked rice can be delayed. Moreover, the activity of bacteria can be suppressed and the decay of cooked rice can be delayed.
[0034]
Using the cooked rice warmer configured as described above, the heat insulation state of cooked rice was examined. First, rice and water, which are raw materials for cooked rice, were put into the inner pot 1 and cooked. Immediately after cooking, the oxygen concentration of the gas in the inner pot 1 was almost 0%, but the inside cooled and the saturated vapor pressure decreased, and air flowed in from the outside, and the oxygen concentration gradually increased.
[0035]
Therefore, 10-20 W of electric power is supplied to the heater 24 of the nitrogen supply means 15 using the heater power supply 25, and the operating temperature of the oxygen pump composed of the solid electrolyte 20 and the pair of electrodes 21, 22 is 600-700 ° C. It heated so that it might become. Then, a predetermined voltage is supplied between the pair of electrodes 21 and 22 by the voltage supply device 23, the gas transport means 16 is further operated, and the nitrogen-enriched gas and water vapor are introduced into the inner pot 1 through the water vapor supply means 17. Supplied. The nitrogen supply amount can be changed by controlling the voltage supply device 23 and the gas transport means 16 by the control means 6.
[0036]
FIG. 4 shows the relationship between the heat retention time and the oxygen concentration in the inner pot 1 when the nitrogen supply means 15 replaces the air in the inner pot 1 with a nitrogen-enriched gas. Oxygen separated by the oxygen pump is discharged to the outside at 10 to 30 cc per minute, and the separated nitrogen is mixed with air again to become a nitrogen-enriched gas, continuously in the inner pot 1 at 40 to 120 cc per minute. To be supplied. As a result, the air in the inner pot 1 is quickly replaced with a nitrogen-enriched gas, and the oxygen concentration in the inner pot 1 is 2 to 4% in 20 to 60 minutes. Retained. The oxygen concentration in the inner pot 1 increased due to the inflow of external air after a while, but the oxygen concentration in the inner pot 1 can be quickly reduced by increasing the nitrogen supply amount again at a low concentration stage to some extent. I was able to. Further, at this time, it was found that the inside of the inner pot 1 is almost at atmospheric pressure, and the airtight structure is simple.
[0037]
Next, immediately after cooking, the oxygen concentration in the inner pot 1 was maintained at 2 to 4%, and sensory evaluation was performed when water vapor was supplied by the water vapor supply means 17. When kept in the atmosphere, the cooked rice was slightly oxidized and the evaluation of heat retention odor and taste was low, whereas when kept at low oxygen concentration and water vapor was supplied, there was little heat retention odor and taste It was good too.
[0038]
Furthermore, when the sensory evaluation of the cooked rice that had been kept warm for 12 hours and 24 hours in this state, both had a little warming odor, had a freshly cooked odor, little yellowing, sticky taste evaluation, and elasticity The overall evaluation was high. On the other hand, the cooked rice that had been kept warm for 12 hours and 24 hours in the atmosphere had a strong warming odor, yellowing occurred, was dry and tasted poor, and the overall evaluation was low.
[0039]
Next, the heat insulation state of the cooked rice when the lid 8 was opened and closed was examined. Immediately after the lid 8 was opened, the oxygen concentration in the inner pot 1 became equal to the oxygen concentration in the atmosphere and became 20.8%. When the lid 8 is closed, the open / close detection means 19 detects that the lid 8 is closed, and the nitrogen supply means 15, the water vapor supply means 17, the valve 18 and the gas transport means 16 operate. The air in the inner pot 1 was quickly replaced with nitrogen-enriched gas, and the oxygen concentration in the inner pot 1 became 2 to 4% in 20 to 60 minutes. Therefore, the nitrogen supply amount was reduced and held as it was. The oxygen concentration in the inner pot 1 increased due to the inflow of external air after a while, but the oxygen concentration in the inner pot 1 can be quickly reduced by increasing the nitrogen supply amount again at a low concentration stage to some extent. I was able to.
[0040]
Further, when the open / close detection means 19 detects that the lid 8 is closed from the open state in the state of keeping the temperature, by controlling the output of the water heating means 17b, the amount of water vapor to be supplied can be increased or after a certain period of time. Since the amount of water vapor to be supplied is reduced, even if the water vapor concentration in the inner pot 1 is reduced by opening and closing the lid 8, water vapor can be supplied to the rice, preventing the warming odor and yellowing of the rice during the heat insulation. , Can prevent a decrease in taste.
[0041]
The sensory evaluation of the cooked rice when the lid 8 was opened and closed also showed comprehensively good results such as a warm odor, yellowing of cooked rice, and physical properties of the taste.
[0042]
Moreover, it turned out that delicious cooked rice with few heat retention odors can be provided by changing supply_amount | feed_rate of nitrogen-enriched gas and water vapor | steam according to the quantity of the cooked rice.
[0043]
【The invention's effect】
As described above, according to the cooked rice warmer of the present invention, nitrogen supply means for removing oxygen contained in the atmosphere and supplying nitrogen-enriched gas, steam supply means for supplying steam to the inner pot, It is equipped with a control means to control nitrogen supply and water vapor supply into the kettle, and it suppresses yellowing of rice and deterioration of physical properties during taste by using nitrogen-enriched air and water vapor, and is delicious even if kept warm Rice is obtained.
[Brief description of the drawings]
1 is a cross-sectional view showing a schematic configuration of a rice cooker in an embodiment of the present invention. FIG. 2 is a cross-sectional view of a nitrogen supply unit of the rice cooker. FIG. 3 is a voltage-current characteristic diagram of the nitrogen supply unit. [Chart 4] Characteristic diagram showing the relationship between the heat retention time and oxygen concentration of the rice cooker
DESCRIPTION OF SYMBOLS 1 Inner pot 4,11 Temperature detection means 5, 7, 10 Heating means 6 Control means 8 Cover 15 Nitrogen supply means 16 Gas transport means 17 Water vapor supply means 17a Water storage means 17b Water heating means 19 Opening / closing detection means 20 Solid electrolyte 21, 22 A pair of electrodes 23 Voltage supply device 24 Heater 25 Heater power supply 26 Heat insulating material 27 Sealing material 28 Current detection means

Claims

An inner pot for storing cooked rice, an openable / closable lid provided above the inner pot, heating means for heating the cooked rice in the inner pot, temperature detecting means for detecting the temperature of the inner pot, and in the atmosphere Nitrogen supply means for removing oxygen contained therein and supplying nitrogen-enriched gas to the inner kettle, gas transport means for transporting nitrogen-enriched gas, water storage means for storing water in advance, and the water storage means A steam supply means for supplying steam to the inner pot comprising a water heating means for heating; and heating control of the cooked rice to a predetermined temperature using the heating means based on a detection value of the temperature detection means; and the nitrogen A rice cooker comprising control means for controlling supply of nitrogen from the supply means to the inner pot and supply of steam from the steam supply means to the inner pot.