グルタミン酸脱炭酸酵素（GAD）活性を利用したたくあん漬けのγ-アミノ酪酸（GABA）含量の変化について検討を行った．新鮮ダイコンのGABA含有量0.28±0.01mg/g乾燥重（DW）に対して，日干しまたは塩押しといった脱水処理により4.93∼9.07mg/g DWまで増大した．グルタミン酸（Glu）は5.72±0.23mg/g DWから0.59∼0.85mg/g DWまで減少した．GAD活性は新鮮ダイコンで最も高く，脱水·塩蔵処理にともない顕著に低下した．食塩と同時に0.1∼0.5%のグルタミン酸ナトリウム（MSG）を添加することで，さらに1.2∼3倍まで増大させることができた．MSG添加した塩蔵ダイコンの上がり水に，経時的なGluの低下とGABAの増大が認められた．微生物により変換されたGABAが塩蔵ダイコンに移行することが示唆された．塩蔵ダイコンの色は，無添加ダイコンでは淡黄色を保持していたが，MSG添加したダイコンは，塩蔵2ヶ月を超えると，くすんだ灰色に変色した．これらの結果から，MSGの添加は塩蔵ダイコンのGABAを富化させることはできるが，色の変化により塩蔵による保存寿命を短縮させることが明らかになった．

This study was performed to clarify the enhancement of the 4-methylthio-3-butenyl isothiocyanate induced yellowing of salted radish root (takuan-zuke) by low pH during short-term salt-aging at low temperature and low salinity. We used two different methods to prepare the dehydrated daikon prior to salt-aging: air-drying outdoors (hoshi takuan-zuke) or salting with a stone press (shio-oshi takuan-zuke). Low salt-aging at low temperature was carried out under pH control with citrate-phosphate buffer. The yellowing of both types of takuan-zuke was accelerated below pH 5, and the color of air-dried takuan-zuke was deeper than that of salt-pressed takuan-zuke. To elucidate this phenomenon, several previously reported yellowing-related compounds were analyzed by high-performance liquid chromatography. The result showed that the production of the primary pigment, 2-[3-(2-thioxopyrrolidin-3-ylidene)methyl]-tryptophan, was low compared with that in previous reports. Therefore, we suggest that an unknown pigment was generated through a previously unreported pathway.

2-thioxo-3-pyrrolidinecarbaldehyde (TPC) is an important intermediate in the yellowing of Japanese pickles “takuan-zuke”. TPC has been reported to have antibacterial activity against bacteria causing food poisoning and microorganisms associated with the development of caries, as well as various physiological functions such as antimutagenicity. However, since TPC has high reactivity, robust quantitative analysis is difficult with the extraction method or pre-column derivatization method using 2,4-dinitrophenylhydrazine. In this study, a high-performance liquid chromatography (HPLC) method involving labeling with 4-(N,N-dimethylaminosulfonyl)-7-hydrazino-2,1,3-benzoxadiazole (DBD-H) was developed for the determination of the level of TPC in takuan-zuke. DBD-TPC was successfully stabilized by adding a buffer solution to the reaction solution, which established continuous analysis by HPLC using an autosampler. The DBD-TPC calibration curve was linear in the range of 0.25–250 nmol/mL (final concentration) and showed a wide dynamic range. The lower limit of detection was 0.205 nmol/mL in TPC standard. The proposed method was successfully applied to the measurement of TPC in daikon-oroshi. The results reveal the possibility of determining the variation of TPC level in processed foods containing radish. We concluded that the proposed method is useful for evaluating the quality of processed radish products.

White radish root (daikon) is an important vegetable in Japanese food culture and has spawned the development of various cooking and processing methods. takuan-zuke is the major processed food derived from daikon. Takuan-zuke is prepared by the dehydration of the root using a salt-press or a weighted stone, or by sun-drying, followed by salt-aging using salt or salted rice bran. The color of takuan-zuke changes to yellow during salt-aging. We determined the effects of dehydration and salt-aging on the metabolism of daikon using takuan-zuke. In the yellowing reaction, the generation of daikon isothiocyanate was significant, requiring a temperature of ≥10°C and pH ≥5. The color change of the sun-dried takuan-zuke was the most significant. Moreover, we investigated the nutritional characteristics of takuan-zuke. In the sun-dried daikon, metabolism progressed for 3 weeks during drying, with increase in the concentrations of γ-aminobutyric acid (GABA) and proline as well as drying stress metabolites. In the salt-pressed daikon, GABA concentrations temporarily increased due to osmotic stress but then decreased on metabolic inhibition by salt permeation. In addition, no change in the concentration of proline was observed under salt-press conditions. The results showed a marked difference between the stress response of the living and processed root.

Originally, the manipulator played an auxiliary role of man. However, when a manipulator's workspace expanding and the cooperation work with people is taken into consideration, the development of manipulator with the capability as more man-like an "arm". Then, in this paper we design the joint part which imitated movement of man's shoulder joint for the junction part connecting the frame and a articulated manipulator. Because heavy weight acting on a shoulder joint, it is composed the parallel mechanism which is the form driven by two or more actuators. Moreover, in the manipulator which is connected by the shoulder joint, a wrist and an elbow joint is arranged serially. This research examines the practicality about the manipulator that combined a serial and parallel form.