Characterization of Different Orchid Species and Rheological Properties of Orchid Solutions

Abstract

This study investigated the physicochemical, bioactive, and rheological properties of salep obtained from ten different wild orchids collected from different regions of Turkey (Anacamptis pyramidalis, Orchis isaura, Anacamptis palustris subsp. palustris, Orchis morio, Serapias vomeracea subsp. artemisiae, Orchis italica, Ophrys mammosa, Orchis sancta, Dactylorhiza euxina, Ranunculus ficaria subsp. calthifolius, and commercial salep). Firstly, the salep samples were ground and their color, pH, bioactive components, and FTIR spectrum were determined. The color and pH properties of salep differed due to the different species (p≤0.05). Two strong peaks were observed at 1618 and 1422 cm-1 due to asymmetric and symmetric stretching of the ester groups in salep glucomannan. According to salep species, there was a significant difference in the TPC (total phenolic content), % DPPH (2,2-diphenyl-1-picrylhydrazyl) scavenging activity, and CUPRAC values (p≤0.05), which were 5.29-26.84 mg GAE/g, 5.02-12.2%, and 0.81-3.82 mg TE/g, respectively. The FTIR findings revealed that the spectrum peaks did not change between commercial salep and other salep species. In the second part of the study, we prepared 1%, 2%, and 3% aqueous solutions of salep and examined their flow behavior, dynamic rheological properties, and 3-ITT (3-Time Interval Thixotropic Test) rheological behavior. A significant difference was observed between the values (p≤0.05). All salep solutions had a flow behavior index (n) value below 1, indicating that all samples exhibited shear-thinning behavior. The consistency coefficient (K) value significantly changed (p≤0.05) and was determined to be 0.003-2.91 Pa.sn, 0.003-28.81 Pa.sn, and 0.017-94.134 Pa.sn at salep concentrations of 1%, 2%, and 3%, respectively. Salep is a preferred stabilizer due to its functional properties, bioactive components, and polysaccharide structure. As a result, when the rheological properties of salep samples are evaluated, it is shown that especially Anacamptis pyramidalis, Orchis morio, Orchis sancta species can be used as stabilizers in the food industry.