Quantification of Ash and Moisture in Wheat Flour by Raman Spectroscopy

Tomasz Czaja,Aldona Sobota,Roman Szostak

doi:10.3390/foods9030280

Abstract

Wheat flour is widely used on an industrial scale in baked goods, pasta, food concentrates, and confectionaries. Ash content and moisture can serve as important indicators of the wheat flour’s quality and use, but the routinely applied assessment methods are laborious. Partial least squares regression models, obtained using Raman spectra of flour samples and the results of reference gravimetric analysis, allow for fast and reliable determination of ash and moisture in wheat flour, with relative standard errors of prediction of the order of 2%. Analogous calibration models that enable quantification of carbon, oxygen, sulfur, and nitrogen, and hence protein, in the analyzed flours, with relative standard errors of prediction equal to 0.1, 0.3, 3.3, and 1.4%, respectively, were built combining the results of elemental analysis and Raman spectra.

Highlights

Wheat flour is the most important product of wheat milling
We present a new, fast, and reliable Raman spectroscopic method for ash, moisture, and protein quantification in wheat milling fractions
The fluorescent background is more pronounced for the samples with higher ash content

Summary

Introduction

Wheat flour is the most important product of wheat milling. The ash obtained from flours consists of mineral compounds of phosphorous, potassium, calcium, magnesium, iron, zinc, and copper. The whole wheat grain contains 1.17–2.96% of the mineral constituents [5]. This variation is caused by the genotype, wheat class and cultivar as well as the growing location and year [4]. Flour characterized by a higher ash level is usually less purified and contains more particles of fine bran and endosperm adjacent to the bran. From a nutritional point of view, an increase in the ash content in flour combined with an increase in the content of dietary fiber, vitamins, and non-gluten proteins is desirable [7]. Measurement of the ash content is routinely performed using a standard

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Conclusion