Oligosaccharides, and in particular raffinose and kestoses, are of great importance not only in the field of cane and beet processing but also in respect of the analyses of a number of agricultural raw materials and trade products. The analytical and technological problems related to the presence of these compounds in factory juices are well known. In particular, the amount of raffinose, which increases inside beet roots during their storage under cold conditions, leads to a falsely high polarization, it slows down the kinetics of crystal growth and it causes the formation of sucrose needle crystals which are difficult to centrifuge and pack. Recently it has been pointed out that kestoses can also promote major habit modification of sucrose crystals due to their presence inside the lattice which causes a distortion of the lattice itself. The presence of kestoses has always been considered in connection with cane processing but considerable amounts of kestoses can be found even in beet processing, depending upon both the origin of the raw material and the type of technology adopted. In fact, kestoses can be decomposed under the particular pH and temperature conditions of the calco-carbonic purification process, but they can even be found in molasses and, in particular, in molasses originating from the direct crystallization of beet raw juice. The importance of the detection of the presence of raffinose in juices from Steffen processing or the chromatographic separation of molasses is well known. Recent investigations of beet raw juice chromatography have emphasized how important is the detection of both raffinose and kestoses which, if present in the «extract» fraction, can lead to shape and kinetic modifications of the final sucrose crystals. Beside the problems related to beet and cane processing, oligosaccharides, and kestoses in particular, are becoming increasingly important due to their characteristics as pre-biotic compounds. The commercial production of mixtures of kestoses via enzymatic processes is in operation industrially but extraction processes from different raw materials are being studied moreover transgenic sugar beet is being investigated with the objective of obtaining a crop that produces fructo-oligosaccharides. It is clear from the points mentioned above how important the setting up of simple and reliable analytical techniques can be for the detection of oligosaccharides in different materials. We believe that modern planar chromatography can be utilized, bearing in mind that HPTLC plates and AMD (Automated Multiple Development) completely automated elution systems, including sample positioning and spots detection, are available. Details on the analytical methodology adopted for molasses and other sugar products are presented and discussed also giving statistical data about its accuracy and precision. G. VACCARI, G. LODi, E. TAMBURINI, E. DOSI and G. MANTOVANI University of Ferrara, Ferrara, Italy

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Auteur : G. VACCARI G. LODi E. TAMBURINI E. DOSI G. MANTOVANI