Investigation of starch hydration by 2D time domain NMR

Proton exchange between spin groups of the solid matrix of hydrated granular potato starch and water was studied using the 2D time domain NMR. The proton spin-spin relaxation time T$\text{}_{2}$, and spin-lattice relaxation time T$\text{}_{1}$ (selective and non-selective pulse sequences) were measured at room temperature. The observed spin relaxation results were analysed for exchange assuming a two-site exchange model (between water and solid matrix of starch). In this analysis we determined the intrinsic spin-lattice relaxation time for water protons (49 ms) and solid starch matrix protons (172 ms), as well as the water-starch magnetization exchange rate (86 s$\text{}^{-1}$)

Badanie sorpcji metali ciężkich przez bulwy ziemniaczane

In the paper a potential application of potato tubers for the removal of heavy metals from aqueous solutions was investigated. Sorption of Cu2+, Fe5+ and Pb2+ was studied for different salts in order to determine the influence of counter anions on the cation uptake by the investigated adsorbents. Potatoes in the form of raw and dried potato cubes and the peels were soaked in 5 % aqueous solution of the following salts: copper(II) acetate, chloride and sulfate, iron(III) chloride and nitrate(V) and lead(II) acetate and nitrate(V). After sample wet mineralization with HNO3 and HClO4, the total metal content was determined by the inductively coupled plasma atomic emission spectroscopy (ICP-AES). The inner structure of the applied sorbents was determined by using the scanning electron microscopy (SEM). Sorption was found to be dependent on both the cation and the anion present in the solution. Acetate ions significantly enhanced the metal uptake from the solution. In all studied samples the uptake of Pb2+ was most effective in comparison with that for the other cations. Among the sorbents, the potato peels have taken higher, than it was obtained for the others, amount of metals, and the raw potato cubes were more effective compared with the dried ones. The metal uptake was positively correlated to the moisture and protein content as well as the amount of Ca2+ and K+ ions in the initial samples. It was also related to the inner structure of used potato materials. The obtained results should be useful in the recovery of the heavy metals from the environmental samples.W pracy badano sorpcję metali ciężkich przez bulwy ziemniaczane oraz wpływ różnych anionów na wydajność tego procesu. Badano sorpcję Cu2+, Fe3' i Pb2+ z 5 % roztworów wodnych soli, takich jak octan, chlorek i siarczan(VI) miedzi(II), chlorek i azotan(V) żelaza(III) oraz octan i azotan(V) ołowiu(II). W roli sorbentów użyto surowe i suszone ziemniaki w postaci kostki oraz skórki ziemniaczane. Całkowitą zawartość metali w próbkach, po ich mineralizacji przy użyciu HNO3 i HClCu, oznaczono metodą ICP-AES. Wewnętrzną strukturę zastosowanych sorbentów określono przy użyciu skaningowej mikroskopii elektronowej (SEM). Stwierdzono, że wydajność sorpcji zależy zarówno od rodzaju kationów, jak i od anionów obecn w roztworze. Obecność jonów octanowych znacznie zwiększała pobieranie kationów z roztworu. Najwiekszą wydajność procesu, bez względu na zastosowany sorbent zaobserwowano dla jonów Pb2+. Wśród sorbentów skórki ziemniaczane okazały się najbardziej efektywnym materiałem wiążącym badane kationy metali ciężkich, a najmniejszą wydajność uzyskano dla suszonej kostki ziemniaczanej. Zauważono pozytywną' korelację pomiędzy ilością kationów metali związaną z danym sorbentem a jego wilgotnością, zawartością białka oraz ilością jonów Ca2+ i K+. Ponadto, struktura wewnętrzna sorbentów była również czynnikiem wpływającym na efektywność procesu. Uzyskane wyniki wskazują, że bulwy ziemniaczane, a zwłaszcza skórki ziemniaczane mogą być przydatne jako biosorbenty do odzyskiwania metali ciężkich z próbek środowiskowych

Characterization of starch nanoparticles

Nanomaterials already attract great interest because of their potential applications in technology, food science and medicine. Biomaterials are biodegradable and quite abundant in nature, so they are favoured over synthetic polymer based materials. Starch as a nontoxic, cheap and renewable raw material is particularly suitable for preparation of nanoparticles. In the paper, the structure and some physicochemical properties of potato and cassava starch particles of the size between 50 to 100 nm, obtained by mechanical treatment of native starch, were presented. We demonstrated, with the aim of the Scanning Electron Microscopy (SEM) and the non-contact Atomic Force Microscopy (nc-AFM), that the shape and dimensions of the obtained nanoparticles both potato and cassava starch fit the blocklets – previously proposed as basic structural features of native starch granules. This observation was supported by aqueous solubility and swelling power of the particles as well as their iodine binding capacity similar to those for amylopectin-type short branched polysaccharide species. Obtained results indicated that glycosidic bonds of the branch linkage points in the granule amorphous lamellae might be broken during the applied mechanical treatment. Thus the released amylopectin clusters could escape out of the granules. The starch nanoparticles, for their properties qualitatively different from those of native starch granules, could be utilized in new applications