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Near-infrared (NIR) spectrophotometers with different optical arrangements were used to measure the diffusely reflected electromagnetic radiation of different types of food additives in polyethylene (PE) foils. Eight compounds, frequently used in food process – but also in other industries –, were measured by different NIR spectrophotometers. The detected (‘as is’) and mathematically transformed (by scatter correction, second derivative combined with smoothing) NIR spectra were processed with multivariate data analysis (MDA). In this matter, unsupervised methods like principal component analysis (PCA) and cluster analysis (CA) were used, which techniques do not require prior information and reference measurements. The aim of the present study was to distinguish food additives by the help of the applied chemometric methods based on NIR spectra detected via the PE foils. Results indicated that distinction of different food additives and compounds with NIR methods is possible not only with the conventional sample preparations and handlings, but also without breaking the packaging.

Open access
Acta Alimentaria
Authors:
M. Hódsági
,
Á. Jámbor
,
E. Juhász
,
S. Gergely
,
T. Gelencsér
, and
A. Salgó

Resistant starches (RSs) are broadly investigated as appropriate additives in starch-based products due to their well-known and proved health benefits. However, it was shown in previous studies that these starches are sensitive of the different heat treatments used in the food processing, which can cause changes, especially in the resistance. There is an increasing trend to use microwave (MW) energy in food processing; therefore, our aim was to investigate the changes of RSs compared to native starches caused by MW heating. Maize, wheat, RS2 and RS4 starches were MW-treated according to a 2×2 experimental design (300 and 600 W of power, 30 and 150 s of time). The changes of in vitro digestibility, rheological properties (rapid visco analyser, RVA) and near infrared (NIR) spectroscopic characteristic were studied. Two spectrophotometers were applied (dispersive and Fourier-transform (FT)) to compare their sensitivity in the analysis of the MW-treated starches.Results showed that the digestibility of starches did not show any tendencies when increasing the microwave energy of treatments, the characteristics of the kinetic curves remained unchanged. The RVA analysis showed that the RSs did not gelatinize after the heat-treatments. The MW heating weakened the rheological properties of all starches. The NIR analysis was the most sensitive device for the detection of the effects of MW treatments. The analysis of the most characteristic carbohydrate regions (2080–2130 and 2270–2290 nm) highlighted structural alterations of the starches; moreover, the dispersive spectrophotometer was found to be more sensitive in the analysis of starches than the FT-one.

Restricted access
Cereal Research Communications
Authors:
T. Abonyi
,
S. Tömösközi
,
M. Budai
,
Sz. Gergely
,
É. Scholz
,
D. Lásztity
, and
R. Lásztity

The proteins that form gluten of a winter wheat cultivar, Ukrainka (HMW-GS composition 1, 7+8, 5+10) grown in Hungary and harvested in the year 2006, was investigated during grain development. The formation of gluten, its protein fractions and composition of polymeric fraction, were followed starting at the 12 th day after anthesis (DAA) to the 52 nd .Gluten formation was first observed (manual method of determination) only 20–25 days after anthesis and its quantity increased rapidly during the next period of grain development. The gluten was separated to a fraction extractable with SDS-phosphate buffer and another fraction, unextractable by this buffer. An increase in the ratio of unextractable polymeric protein (UPP)/soluble protein fraction was observed during grain development. As expected, gliadin was the main component of the soluble fraction and glutenin that of the insoluble one. HMW monomers were detected in unreduced fractions in small quantities only until 30 th DAA. RP-HPLC of reduced gluten fractions showed a slight increase of the ratio HMW/LMW with days after anthesis.An increase of relative viscosity of gluten solutions during grain development was also observed as a sign of polymerization of glutenin subunits and consequently an increase in average molecular weight of glutenin.

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