Endogenous factors responsible for the textural characteristics of buckwheat products.
Endogenous factors responsible for the textural characteristics of buckwheat products were studied. An analysis with various buckwheat samples showed that there were variations in protein, starch, amylose and amylopectin contents among the various buckwheat flours examined. The protein contents of the buckwheat flours were significantly negatively-correlated to the starch, amylose and amylopectin contents of buckwheat. A texturometric analysis showed that the springiness of heated-dough made from buckwheat flour was positively correlated to its starch content and amylopectin content, and the springiness and chewiness was negatively correlated to the protein content. Experiments adding isolated buckwheat protein or starch to buckwheat dough confirmed the above-mentioned correlation between texture and components. This study suggests that both the protein and starch present in buckwheat flour may be important factors responsible for the textural characteristics of buckwheat products.
Near-infrared diffuse reflectance spectroscopic analysis of the amounts of moisture, protein, starch, amylose, and tannin in buckwheat flours.
The feasibility of near-infrared (NIR) diffuse reflectance spectroscopy scanning from 1100 to 2500 nm in the analyses of the amounts of moisture, protein, starch, amylose, and tannin in buckwheat flours was examined. Fifty ground samples comprised of 27 different cultivars harvested in 12 different countries were divided into two sets: 35 samples as a calibration set and 15 samples as a prediction set. The multiple regression equations (MREs) established between the second derivative NIR spectra data and the reference data, which were obtained by chemical analyses of the calibration set, gave multiple correlation coefficients of higher than 0.93 for moisture, protein, and starch, and workable standard error of predictions (SEPs) in relation to the reference standard deviation data. In contrast, the MREs for amylose and tannin were judged as unstable because the SEPs had no difference with their reference standard deviation data. The influential wavelengths were 1925 nm for water (assigned to the combination of the stretching and bending vibrations of hydroxyl [OH]), 2057 nm for protein (assigned to the combination of NH and amide II or III), and 2100 nm for starch (assigned to the combination of OH and CO). The obtained results indicated that the NIR procedure can be used as a nondestructive analysis method for rapid and simple measurement of the amounts of moisture, protein, and starch in buckwheat flours.
Using Partial Least Squares Regression and Multiplicative Scatter Correction for FT-NIR Data Evaluation of Wheat Flours
Scanning Fourier transform near infrared reflectance (FT-NIR) spectroscopy was used to record spectra of roller and commercial milled wheat flours (varieties and mixtures). Partial least squares (PLS) regression of multiplicative scatter corrected (MSC) NIR data was carried out. Correlations to moisture, protein, wet gluten, water absorption and falling number were studied. Promising correlations to these parameters except falling number were obtained for both types of milled samples. Explanation factors (R2) and standard errors of prediction (SEP) in the roller milled flours were as follows: moisture R2 = 0.97 and SEP = O.16 g/100 g; protein R2 = 0.92 and SEP = 0.40 g/100 g d.b. (dry basis); wet gluten R2 = 0.89 and SEP = 1.37 g/100 g; and water absorption R2 = 0.83 and SEP = 0.84 g/100 g. The explanation factor of predicted falling numbers to the actual values of the roller milled flours remained lower than 0.5. Explanation factors and SEP in the commercial milled flours were as follows: moisture R2 = 0.85 and SEP = 0.19 g/100 g; protein R2 = 0.91 and SEP = 0.63 g/100 g d.b.; wet gluten R2 = 0.87 and SEP = 2.22 g/100 g; water absorption R2 = 0.88 and SEP = 1.10 g/100 g; and falling number R2 = 0.55 and SEP = 28.2.