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Open access

Elżbieta Wojtowicz, Aldona Krupska and Renata Zawirska-Wojtasiak

Summary

Introduction: Novel raw materials are being constantly searched for chicory coffee, which thanks to their specific composition can influence human health, thus promoting properties and of course the attractive aroma. Prior to their addition herbs – sea buckthorn (Hippophaë rhamnoides L.), rowanberry (Sorbus aucuparia L.), lovage roots (Levisticum officinale Koch) and dandelion (Taraxacum officinale coll.) – are roasted, which may change their antioxidant properties and generate free radicals with pro-oxidative properties.

Objective: The characteristic of antioxidant activity of roasted herbal raw materials (sea buckthorn fruits, rowanberry, lovage roots and dandelion roots) for the production of chicory coffee and to determine the level of free radicals formed under the influence of roasting.

Methods: Total phenolic contents were determined before and after the roasting process using the Folin-Ciocalteu phenol reagent and antioxidant activity by ABTS and DPPH assays. Free radicals were examined using electron paramagnetic resonance (EPR) spectroscopy.

Results: The roasted materials were good sources of bioactive compounds, estimated at the total phenolic levels from 23.9 to 38.8 mg GAE/g. The highest antioxidant activity by ABTS and DPPH at 109.6 and 71.0 mg Tx/g was determined in roasted sea buckthorn. Free radicals were present in both the raw and roasted herbal materials. Roasted materials were characterised by markedly higher free radical concentrations when compared with the corresponding samples. The lowest free radical concentrations were recorded for roasted sea buckthorn fruits (0.031 × 1015 spin/g).

Conclusion: Despite a high content of compounds with potent antioxidant activity, free radicals were present in novel roasted herbal materials. The formation of both antioxidant molecules and free radicals during the roasting process demonstrates that the two processes were not inversely related.

Open access

Lucyna Słomińska, Roman Zielonka, Leszek Jarosławski, Aldona Krupska, Andrzej Szlaferek, Wojciech Kowalski, Jolanta Tomaszewska-Gras and Marek Nowicki

Abstract

Air dry potato starch (84.9% d.s.) was subjected to pressurizing under the pressure of 50, 100, 250, 500, 750, 1000 and 2000 MPa for 1 h. The physical properties of pressurized starch, such as morphology, surface and crystalline structure, gelatinization parameters, were studied by means of scanning and atomic force microscopy (SEM/AFM), X-ray diffraction (X-ray), differential scanning calorimetry (DSC). The susceptibility to the amylolytic enzyme (α-amylase) was also measured. Application of pressure in the range of 50–2000 MPa results in an increase in the compressed potato starch bulk density, change in the contours of the granules from oval to polyhedral, increase in the roughness of the granule surface, vanishing of the X-ray reflexes generated by the orthogonal structure and weakening of the reflexes generated by the hexagonal structure, lowering of the enthalpy of starch gelatinization, and the enhancement of hydrolytic susceptibility of starch granules to the amylolytic enzyme.