Yasuhisa Nakano

Prediction of the concentrations of ethanol and acetic acid in the culture broth of a rice vinegar fermentation using near-infrared spectroscopy

Abstract Near-infrared spectroscopy (NIR), which is a nondestructive analytical technique, was employed for the simultaneous prediction of the concentrations of ethanol and acetic acid in the culture broth sampled from a rice vinegar fermentation. The broth was placed in a near-infrared spectrophotometer and the absorbance at wavelengths between 400 and 2,500 nm was measured at 2 nm intervals. To obtain calibration equations, multiple linear regression (MLR) was conducted on the NIR spectral data and on the ethanol and acetic acid concentrations obtained by gas chromatography of a calibration sample set. The value of the multiple correlation coefficient (R) was 0.999 when using the wavelengths of 1,686 and 1,738 nm for ethanol. The value of R for acetic acid was 0.940 when using the wavelengths of 1,674 and 1,718 nm. To validate the calibration equations obtained, ethanol and acetic acid concentrations in a prediction sample set which was not used for calibration were calculated using the calibration equation, and compared with the concentrations measured by gas chromatography. Excellent agreement between the results of the conventional method and those of NIR was observed for both constituents. The concentrations of ethanol and acetic acid in the culture broth could be analyzed simultaneously by NIR. The procedure of NIR was simple, and the operation time required to predict the concentrations was only 5 min. These results indicate that NIR may be a useful method for the monitoring and control of rice vinegar fermentation.

Contributions of the opponent mechanisms to brightness and nonlinear models.

Additivity of heterochromatic brightness matching was investigated between unique-green and red (660 nm), and between unique-blue and unique-yellow with 2-deg bipartite field composed of a 100 td white reference field and a bichromatic mixture field. Ten subjects participated in the measurements and the results showed wide varieties among subjects. Previous models for brightness perception based on the contributions of red-green and yellow-blue opponent channels can explain some properties of the results, but they fail to explain other aspects. To overcome the difficulties, a new model is proposed for the brightness perception at photopic levels.

Effects of C N ratio and pH of raw materials on oil degradation efficiency in a compost fermentation process.

Waste oil treatment was attempted using a compost fermentation process. To develop a simple method for waste oil treatment, cheap and simple materials were used as compost materials. The fermentation experiment was performed using a domestic composter to determine the optimum conditions of the fermentation. Adjustment of the pH value during the compost fermentation was also important for progression of the oil degradation. When the pH value was not controlled, the pH value decreased quickly and reached about 2 and the oil degradation was stopped. Adding caustic lime to the raw materials caused the pH value of the compost to stabilize at approximately 7. The addition of a nitrogen source had a large effect on oil degradation during the compost fermentation. The optimum value of the C N ratio of the raw materials with pH control was between 10 and 40. When the C N ratio of the materials was adjusted to 10, 20, and 40, the rate constants for oil degradation were very similar. The rate constants for NH4+ consumption were also similar. Oil degradation efficiency reached 83.5% relative to the initial oil content in the compost materials. Repeated batch operation of the compost fermentation was carried out and the compost system could maintain good efficiency for oil degradation over several repeated batch operations. Finally, the compost system was applied to the treatment of recalled mayonnaise, with favorable results being obtained.

Simultaneous measurement of carbon and nitrogen content of compost using near infrared spectroscopy

Near infrared (NIR) spectroscopy was used to determine the carbon and nitrogen content of compost during compost fermentation of tofu (soybean-curd) refuse. Reflectance measurements in the wavelength range between 400 and 2500 nm were made at 2 nm intervals. The NIR absorption of the carbon components was observed at two wavelengths, 1584 and 1024 nm in the second derivative spectrum. The NIR absorption of nitrogen components was observed at two wavelengths, 2174 and 900 nm in the second derivative spectrum. To formulate a calibration equation, a multiple linear regression analysis was carried out between the NIR spectral data and the carbon and nitrogen content in the calibration sample set (sample number, n = 60) obtained using a Pregie–Dumas combustion method. The values of the multiple correlation coefficient were 0.988 and 0.984, respectively. To validate the calibration equations obtained, the carbon and nitrogen content in the prediction sample set (n = 48), not used for formulating the calibration equation, were calculated using the calibration equations and compared with the values obtained using the Pregie–Dumas combustion method. Good agreement was observed between the results of the Pregie–Dumas combustion method and the NIR method. The values of the simple correlation coefficient were 0.986 and 0.972, respectively. The study indicates that NIR is a useful method for process management of the compost fermentation of tofu refuse.

Spectral luminous-efficiency functions obtained by direct heterochromatic brightness matching for point sources and for 2° and 10° fields

Brightness luminous-efficiency functions for point sources and for 2 degrees and 10 degrees fields are based on 6, 63, and 76 subjects, respectively. The function for point sources can be approximated by Judds 1951 modification of the CIE V(lambda) function. The 2 degrees and 10 degrees functions differ greatly from V(lambda). The two functions differ from each other only at wavelengths from 410 through 520 nm, where the differences are attributed to absorption by the macular pigment.

Rapid measurement and control of the moisture content of compost using near-infrared spectroscopy

In a compost fermentation of soybean-curd (tofu) refuse, the effects of the moisture content of the compost on the compost reaction were studied. The moisture content of the compost was a very important factor for good fermentation. Near-infrared spectroscopy (NIRS) was applied to the determination of the moisture content of the compost. The reflected rays in the wavelength range between 400 and 2500 nm were measured at 2 nm intervals. The absorption of water was observed at three wavelengths, 960, 1406 and 1888 nm. To formulate a calibration equation, a multiple linear regression analysis was carried out between the near-infrared spectral data at 960 nm (sample number, n = 50) and on the moisture content obtained using a drying method. The values of the simple correlation coefficient and the standard error of calibration were 0.987 and 1.33%, respectively. To validate the calibration equation obtained, the moisture content in the prediction sample set (n = 35) not used for formulating the calibration equation was calculated using the calibration equation, and compared with the values obtained using the drying method. Good agreement was observed between the results of the drying method and those of the NIRS method. The simple correlation coefficient and standard error of prediction were 0.979 and 1.85%, respectively. Then, the NIRS method was applied to a practical situation in which the moisture content was measured and controlled during the compost fermentation, and good results were obtained. The study indicates that NIRS is a useful method for measurement and control of the moisture content in the compost of soybean-curd refuse.

Determination of the Content of Water and Rice Bran in Solid Media Used for Mushroom Cultivation Using Near-Infrared Spectroscopy

Abstract Near-infrared spectroscopy (NIR) was employed for the simultaneous determination of the water and rice bran content in solid media used for mushroom cultivation. The solid media were prepared by addition of water to a mixture of sawdust with rice bran and wheat bran. The medium packed in a polyethylene bag was placed in a near-infrared spectrophotometer. The reflected rays, in the wavelength range between 400 and 2500 nm, were measured at 2 nm intervals. To obtain a calibration equation for water content, a simple linear regression was carried out on the near-infrared spectral data at 1450 nm and on the water content of a calibration sample set (sample number, n=113) obtained using dry-weight method. The values of the simple correlation coefficient and the standard error of calibration were 0.995 and 1.33%, respectively. On the basis of the result of a multiple linear regression on the content of rice bran in the solid media, a calibration equation using the second-derivative reflectance data at the wavelengths of 672 and 2100 nm was obtained, with the values of the multiple correlation coefficient and standard error of 0.978 and 1.73%, respectively. To validate the calibration equations obtained, water and rice bran content in the prediction sample set (n=56) not used for formulating the calibration equations were calculated using the calibration equations, and compared with the values obtained using the dry-weight method based on the mixing ratio. For both the water and rice bran content, excellent agreement was observed between the results of the conventional method and those of NIR method. The simple correlation coefficient and standard error of prediction were 0.995 and 1.33% for water content and 0.975 and 1.84% for rice bran content. The content of water and rice bran in the solid media could be analyzed simultaneously by NIR. The NIR procedure was simple, and the operation time required to determine the content was only 5 min. These results indicate that NIR may be a useful method for monitoring the content of water and rice bran in solid media used for mushroom cultivation.

Color fusion and flicker fusion frequencies using tritanopic pairs.

We determined color fusion and flicker fusion frequencies for tritanopic color pairs, so that only short wavelength sensitive cones were modulated. The minimally distinct border (MDB) technique was used to determine tritanopic pairs for each observer. If S-cones do not contribute to the luminance channel, color fusion and flicker fusion frequencies should be equal, because the achromatic flicker perceived beyond color fusion frequency is supposed to be elicited just by the luminance channel. The results show a significant difference between color fusion and flicker fusion frequencies for all pairs and for all subjects, which suggests a contribution of S-cones to the luminance channel. However, the results also showed that the residual achromatic flicker can not be eliminated by adjusting relative luminance of two colors flickering in counter-phase. The relative luminance stayed the same as the MDB setting when residual flicker was minimized. This means that minimum flicker was obtained when L- and M-cones are temporally silenced, and suggests little or no contribution of S-cones to luminance channel. These conflicting results might be explained by phase shift between responses of S-cones and other longer-wavelength-sensitive cones.

Measurement of the concentrations of glucose and citric acid in the aqueous solution of a blood anticoagulant using near infrared spectroscopy

Near infrared (NIR) spectroscopy was employed for the simultaneous prediction of the concentrations of glucose and citric acid in the aqueous solution of a blood anticoagulant solution. The solution was placed in an NIR spectrophotometer and the absorbance at wavelengths between 400 and 2500 nm was measured at 2 nm intervals. Multiple linear regression (MLR) was used to obtain calibration equations relating the NIR spectral data and the glucose and citric acid concentrations of a calibration sample set obtained by enzymatic methods. The value of the multiple correlation coefficient (R) was 0.993 when using the wavelengths of 2274 and 1674 nm for glucose. The value of the simple correlation coefficient (r) for citric acid was 0.993 when using the wavelength 1690 nm. To validate the calibration equations obtained, glucose and citric acid concentrations in a prediction sample set were compared with the concentrations measured by the enzymatic methods. Excellent agreement between the results of the enzymatic method and those of NIR spectroscopy was observed for both constituents. The procedure of NIR spectroscopy was simple and the operation time required to predict the concentrations was a few minutes. These results indicate that NIR spectroscopy may be a useful method for monitoring the production process of the blood anticoagulant.

Predicting methanol and glycerol concentrations in microbial treated wastewater discharged from a biodiesel fuel production process using near infrared spectroscopy

Microbiological treatment of wastewater discharged from purification processes of biodiesel fuel (BDF) produced from waste edible oil with alkaline catalyst was carried out in a 3L jar-fermentor. Wastewater treatment was started by the addition of the seed culture of Rhodotorula mucilaginosa HCU-1 to the medium prepared from oil-removed wastewater. Methanol and glycerol concentrations in the wastewater were predicted simultaneously using near infrared (NIR) spectroscopy. The wastewater containing the microorganism cells in a 1 mm light path length cuvette was placed in an NIR spectrophotometer and the absorbance at wavelengths between 400 nm and 2500 nm was measured at 2 nm intervals. Simple or multiple linear regression analysis was used to obtain calibration equations relating to the NIR spectral data and the content of a calibration sample set (n=66) obtained by the conventional methods. The wavelengths at 2264 nm, and 2274 nm and 2256 nm were selected to make calibration equations for methanol and glycerol, respectively. Prediction of methanol and glycerol contents (n=45) was successfully carried out using NIR spectroscopy with r2=0.996 and SEP=0.637 gL−1 and r2=0.996 and SEP=0.31 gL−1 respectively.