Yoshinobu Naito

Advanced Taste Sensors Based on Artificial Lipids with Global Selectivity to Basic Taste Qualities and High Correlation to Sensory Scores

Effective R&D and strict quality control of a broad range of foods, beverages, and pharmaceutical products require objective taste evaluation. Advanced taste sensors using artificial-lipid membranes have been developed based on concepts of global selectivity and high correlation with human sensory score. These sensors respond similarly to similar basic tastes, which they quantify with high correlations to sensory score. Using these unique properties, these sensors can quantify the basic tastes of saltiness, sourness, bitterness, umami, astringency and richness without multivariate analysis or artificial neural networks. This review describes all aspects of these taste sensors based on artificial lipid, ranging from the response principle and optimal design methods to applications in the food, beverage, and pharmaceutical markets.

Analysis of a Lipid/Polymer Membrane for Bitterness Sensing with a Preconditioning Process.

It is possible to evaluate the taste of foods or medicines using a taste sensor. The taste sensor converts information on taste into an electrical signal using several lipid/polymer membranes. A lipid/polymer membrane for bitterness sensing can evaluate aftertaste after immersion in monosodium glutamate (MSG), which is called “preconditioning”. However, we have not yet analyzed the change in the surface structure of the membrane as a result of preconditioning. Thus, we analyzed the change in the surface by performing contact angle and surface zeta potential measurements, Fourier transform infrared spectroscopy (FTIR), X-ray photon spectroscopy (XPS) and gas cluster ion beam time-of-flight secondary ion mass spectrometry (GCIB-TOF-SIMS). After preconditioning, the concentrations of MSG and tetradodecylammonium bromide (TDAB), contained in the lipid membrane were found to be higher in the surface region than in the bulk region. The effect of preconditioning was revealed by the above analysis methods.

Detection of agricultural chemicals using a lipid membrane sensor

Describes a measurement method to detect ppm level of noncharged agricultural chemicals using a lipid/polymer membrane sensor within five minutes. In the case of this new measurement method, non-charged toxic substances are detected indirectly. Sensor output is change of membrane potential caused by interaction among lipid membrane, agricultural chemicals and lipid in a solution. This, method has a possibility of detection of a trace amount of agricultural chemicals. It is useful for the evaluation of safety of vegetables and fruits.

Detection of noncharged organic substances by new measurement method using a lipid membrane sensor

This paper reports a new measurement method to detect ppb levels of noncharged organic substances using lipid/polymer membrane sensors. Noncharged organic substances have large influences on the adsorption of positively-charged lipids to negatively-charged membranes. Organic solvents (trichloroethylene) and endocrine disrupting chemicals (di-2-ethylhexylphthalate) were detected by utilizing the sensor output, which is the change of membrane potential caused by interactions among the lipid membrane, noncharged organic substances, and lipids in solution. This new potentiometric method has a possibility of detection of a trace amount of noncharged toxic substances.

Detection of Agricultural Chemicals of Leaf Vegetables Using a Positively Charged Lipid Membrane Sensor

This paper describes a measurement method to detect a ppb level of agricultural chemicals within five minutes using a lipid/polymer membrane sensor. Noncharged organic substances have large influences on the adsorption of positively charged lipids to negatively charged membranes. In this study, noncharged agricultural chemicals in the washed vegetables (spinach, broccoli and Japanese basil) solution can be detected. These substances can be detected above 2000 ppb in these solutions. In the case of spinach and broccoli, it can be considered that agricultural chemicals inhibit the adsorption of the adsorbent in solution to the positively charged lipid membrane, because the change rate is below zero. In the case of Japanese basil the agricultural chemicals have a synergetic effect on the adsorption of the adsorbent to the lipid membrane. These results show that noncharged agricultural chemicals can be detected indirectly. We obtained a possibility that agricultural chemicals can be classified before an accurate chemical analysis. It is useful for the evaluating safety of vegetables and fruits.