The X‐ray wide‐angle scattering patterns of legume starches are attributed to the C‐type in contrast to the A‐ and B‐type of cereal and root starches. Starting from the question if this C‐pattern is to be considered as a mixed A‐ and B‐type or as an independent X‐ray wide‐angle diffractogram. examinations have been performed with starches from Vicia faba and Pisum sativum in comparison with pure A‐ and B‐type starches from maize and potato. The phase proportions in the crystalline parts of the C‐starches were calculated by means of a linear regression method. The pea starch is composed of 38.6% type B and 61.4% type A, and for the starch of bean we calculated 17.0% type B and 83.0% type A. By these results as well as by the high values for the correlation coefficients it is proved that the starch C‐polymorph is a mixture of A‐ and B‐unit cells. The legume starches consist of starch granules of pure A‐type as well as of pure B‐type in varying relations.

No abstract

Thermally reversible maltodextrin gels are two-phase systems, composed of disc-like crystalline domains with a diameter of about 300 nm and regions containing amorphous polymer chains and water. The structure of the polysaccharide chains within the lamellae is that of the crystalline B-form of amylose, the polymer chains are arranged in double-stranded helices, which are packed in a hexagonal unit cell (a = b = 1.85 nm, c (fiber repeat) = 1.04 nm, ~, = 120~ As revealed by measurements of the excess wide-angle X-ray scattering of the polysaccharide, gelation of the solutions is due to a partial crystallization of the polymer. In non-gelling maltodextrin solutions a crystallinity cannot be detected.

In maltodextrin gels the junction zones of the network are microcrystalline domains consisting of polysaccharide chains. Such microcrystalline aggregates already exist in a 10% maltodextrin solution. If the degree of crystallinity rises above loyo, a gel is formed. In the 25% gel, ISYO of the polysaccharide chains are involved in these junction zones. As calculated from the integral breadth of the peaks ,the crystallite size of 17 nm is considerable smaller than the maximum dimension of 280 nm of the domains found by small-angle X-ray scattering. This discrepancy is caused by lattice distortions in the crystalline domains. Consequently, each domain is composed of microcrystallites. Realstruktur eines teilkristallinen Maltodextringels abgeleitet aus der Rontgen-WeitwinkelstreuungIn Maltodextringelen sind die Haftpunkte des Gelnetzwerkes mirkokristalline Bereiche von Polysaccharidketten. In 10yoigen Losungen von Maltodextrinen existieren bereits derartige mikrokristalline Aggregate. Steigt der Kristallinitatsgrad uber loyo, so gcliert die Losung. In einem 25yoigen Gel sind 16% der Polysaccharidketten Bestandteil dieser mikrokristallinen Haftpunkte. Die aus den Reflexbreiten berechnete KristallitgroBe von 17 nm ist deutlich kleiner als der aus der Rontgen-Kleinwinkelstreuung bestimmte groBte Durchmesser der kristallinen Regionen von 280 nm. Diese Diskrepanz wird durch Gitterstorungen in den kristallinen Bereichen hervorgerufen. Die Gitterstorungen bewirken, daB jeder Bereich aus vielen Mikrokristalliten aufgebaut wird. Hacmomqam cmpykmypa uacmuuno-~ppUcmafifiuuecRozo z e m ntafibmoaemrnpunos, nofiyllennam uantepenufi.~ penmzenosckozo paccesnurc no8 6ofiazuu.u~ y z f i m u B FeJIFIX ManTOAeKCTpHHOBTOYKaMH CqenJIeHHFI HBJIRmTCR MHKpOKpHCTanJIHYeCKHe 06JIaCTH IIOJIHCaXapHAHblX qenefk. Taxme MHHpOKpHCTannHYeCKMe ElrrpeI'aqllll CylIJeCTByIoT y?Ke B 1oo/,HblX PaCTBOpaX MaJIbTOAeKCTpHHObB. ECZH CTeneHb KPHCTannHqHOCTH IIpeBbIIIIaeT loyo, TO PaCTBOp ?KeJlHpyeT. B 25y0~OM reJIe 16% IIOJlHCaXapHRHbIX 4eIIefk BXOAHT B COCTaB BTHX MHKpOKpACTanJIHqeCKklX TOqeK CqenneHHR. Pa3Mep KpHCTannHTOB, PaCCWiTaHHbIfi H3 IUHPHHOfk OTpa?KeHHfk, COCTaBJIReT 17 HM, YTO CyqeCTBeHHO HHXe 280 HM -HaH60nbIUerO AHaMeTpa

X-ray small-and medium-angle scattering of partially ordered or semicrystalline materials is composed of background scattering from the form scattering of the components and from the amorphous phase and of peaks from the scattering of the crystallites. By the slit geometry of X-ray diffractometers constructed for registration of small-and medium-angle X-ray scattering, the diffuse scattering and the peaks are distorted and the peak positions and half-widths are changed. A program module based on the Akima interpolation [Akima (1970). J. Assoc. Comput. Math. 17,[589][590][591][592][593][594][595][596][597][598][599][600][601][602] is proposed for calculation of the first derivative of the complete smeared scattering curve, which is then explicitly used in direct collimationcorrection procedures. The desmearing of scattering curves from semicrystalline starch samples proves the convenience of the method for low-noise conditions and exhibits a significant gain of measuring time in comparison with data of comparable accuracy but measured with SoUer-slit collimation systems or desmeared with direct methods using frequency filtering.