Authors:T. Gelencsér, R. Juhász, M. Hódsági, Sz. Gergely, and A. Salgó
Resistant starches (RS) can be used in the food industry aiming to enhance the dietary fibre content and reduce the glycaemic response of food. The aim of the present study was to investigate the physical and chemical properties of different resistant starches (origin, type of resistance) and their comparison with native starches in pure form and in stoichiometric mixtures. Measurements were carried out to determine enzymatic digestibility, water absorption, thermogravimetric parameters (DSC), and viscometric characteristics (RVA) of resistant and native starches and their mixtures. Enzymatic digestibility and water absorption were reduced linearly by adding resistant starches into the mixtures. RVA parameters have shown non-proportional character in the stoichiometric mixtures. The results of DSC measurements proved that the gelatinisation of resistant starches is quite different and only chemically modified resistant starch was heat-sensitive. Results indicated that circumspect evaluation is needed in the selection of resistant starch products for the development and innovation of food products with reduced glycaemic response.
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.