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Cassava ( Manihot esculenta Crantz) starch prepared from fresh roots of M4 cultivar was complexed with oxalic, malonic and succinic acids. The products were examined for their physicochemical, structural and enzyme digestibility properties. The results were compared to that of untreated starch sample. The properties looked into were swelling, solubility, intrinsic viscosity, amylose (blue value), free reducing sugars, pH and carboxyl content. Enzyme digestibility pattern was examined with respect to α - and β -amylases. Crystallinity of the sample was checked by means of X-ray diffractometry, and their IR spectra were taken and compared. Pronounced increase in aqueous and DMSO solubility was noticed in the case of starch–oxalic acid and starch–malonic acid complexes. These samples, also showed relatively higher carboxyl content and their pH turned to acidic range. pH value was lowest (2.4) in the case of starch–oxalic acid complex. Amylose content was also found to be the lowest in these samples. Among the three starch–acid complexes, starch–succinic acid complex showed relatively less change in these properties. α -amylase digestibility pattern of both untreated and experimental samples revealed highest resistance to enzyme digestibility by starch–succinic acid complex. However, this resistance could not be observed with respect to β -amylase. Both X-ray diffraction pattern and IR spectra of all the starch samples were generally similar.

Fresh samples of Xanthosoma sagitifolium were pretreated with sodium hexametaphosphate (SHMP), potassium metabisulphite (KMS), sodium chloride (NaCl) and aqueous ammonia, all in a concentration range of 1-5 % (w/v), and with glyceryl monostearate (GMS) at 0.025–0.125 % concentrations. The properties of these pretreated samples were compared with those of the control obtained by direct water extraction. The properties of the starch pretreated with chemicals showed characteristic changes regarding amylose contents, especially soluble amylose, and lipid extractability. Starch samples prepared from fresh roots pretreated with sodium chloride displayed a lower amylase digestibility. Control starch samples and the one prepared from roots pretreated with 5 % aqueous ammonia showed the highest amylase activity at 20 min incubation time. Other experimental samples showed only marginal changes.

Fresh roots of Amorphophallus paeoniifolius were separately pretreated with sodium hexametaphosphate (SHMP), potassium metabisulphite (KMS), sodium chloride (NaCl), and ammonium hydroxide (NH4OH) within a range of 1–5% (w/v) concentration and glyceryl monostearate (GMS) at 0.025–0.125% concentration. The quality of starch extracted from pretreated roots was compared with that obtained from fresh roots by direct aqueous extraction. The starch samples prepared from chemically pretreated roots showed characteristic changes in properties of water soluble amylose content, swelling and solubility and α-amylase susceptibility. X-ray diffraction of starch samples from chemically pretreated roots although resembled that of control, there was noticeable shift with respect to their ‘d’ spacing and Io/Imax values.

Cassava and maize starches were subjected to lintnerization under identical experimental conditions using 2·0 m hydrochloric acid. The filtrate and residual starch samples were separated at 5-day intervals up to 35 days. There were considerable changes in amylose content, viscosity, and cold water solubility values. Despite the α- and β-amylase susceptibility patterns being quite distinct, there were less perceptible changes between cassava and maize. X-ray diffractograms of lintnerized samples showed greater crystalline peaks than native samples.

Properties of cassava starch could be modified by subjecting to alkalitreatment under controlled experimental conditions. Modified starch samples showed lower amylose content and higher alkali number. Compared to untreated starch samples, alkali modified starches had higher α-amylase (Bacillus sp.) susceptibility. The properties could be advantageously made use of for preparing maltodextrins having DE 20–23. Untersuchungen uber alkalimodifizierte Cassavastarke - Anderungen der strukturellen Eigenschaften und der enzymatischen Angreifbarkeit (α-Amylase). Die Eigenschaften von Cassavastarke konnten durch Alkalibehandlung unter kontrollierten experimentellen Bedingungen modifiziert werden. Modifizierte Starkeproben zeigten niedrigere Amylosegehalte und hohere Alkalizahlen. Im Vergleich zu unbehandelten Starkeproben haben alkalimodifizierte Starken hohere Empfindlichkeit gegenuber α-Amylase (Bacillus sp.). Diese Eigenschaften konnen vorteilhaft fur die Darstellung von Maltodextrinen mit DE 20–23 genutzt werden.

An attempt has been made to prepare β-cyclodextrin (CD) from cassava starch. Freshly prepared samples of cassava starch from M-4 variety was treated with Standard cyclodextrin glycosyltransferase and the product obtained was converted to bromobenzene and chloroform chlathrates. The product was identified by non-chromatographic spectrophotometric assay and by thermal decomposition behaviour. The bromobenzene β-CD clathrate showed a distinct pattern of thermal degradation compared to that of both pure β-CD as well as β-CD chloroform chlathrates. The yield of the product isolated is approximately 10% (w/w) based on starch.

Experimental conditions for bioconversion of starch to get higher yield of s-cyclodextrin using cyclodextrin glycosyl transferase (CGT-ase) (EC 2.4.1.19) were worked out. A 5% initial starch concentration gave s-CD yield of 20-28% that could be separated as s-CD bromobenzene complex from the reaction mixture. Addition of bromobenzene during the second phase of the reaction, i.e. CD formation phase, was found beneficial. Verbesserte Reaktionsbedingungen zur Darstellung von s-Cyclodextrin (s-CD) aus Cassava (Manihot esculenta)-Starke Verbesserte Reaktionsbedingungen zur Darstellung von s-Cyclodextrin (s-CD) fur die Biokonversion von Starke zum Erhalt einer hoheren Ausbeute an s-Cyclodextrin unter Verwendung von Cyclodextrin-Glycosyltransferase (CGTase) (EC 2.4.1.19) wurden ausgearbeitet. Eine 5%ige Ausgangs-Starkekonzentration ergab eine s-CD-Ausbeute von 20-25%, die als s-CD-Brombenzolkomplex aus dem Reaktionsgemisch abgetrennt werden konnte. Es wurde gefunden, das der Zusatz von Brombenzol wahrend der der zweiten Reaktionsphase, d.h. der CD-Bildungsphase, vorteilhaft war.

A few samples of maltodextrins procured commercially were studied in detail for some of their specific physicochemical qualities. In addition to the Dextrose Equivalent value (DE) the samples were analysed for their cold water solubility and clarity, percent age of cold water solubles, and total hydrolyzable carbohydrates. Samples were also analyzed for their hygroscopicity at different relative humidities varying from 40 to 95%. The carbohydrate profile was studied using HPLC and X-ray diffraction pattern were taken and compared. When samples were tried for flavour encapsulation it could be noticed that samples considerably differed in their encapsulation behaviour. Untersuchungen zur Materialcharakterisierung an Maltodextrinproben fur die Verwendung als Wandmaterial. Einige im Handel bezogene Maltodextrinproben wurden hinsichtlich spezifischer physikalisch-chemischer Qualitatsmerkmale detailliert untersucht. Zusatzlich zum Dextroseaquivalent (DE) wurden die Proben auf ihre Kaltwasserloslichkeit und Klarheit, ihren Prozentgehalt an kaltwasserloslichen Stoffen und die gesamten hydrolysierbaren Kohlenhydrate analysiert. Die Proben wurden auch auf ihre Hygroskopizitat bei verschiedenen relativen Feuchten zwischen 40 und 95% gepruft. Unter Verwendung von HPLC und des Rontgenbeugungsmusters wurde das Kohlenhydratprofil studiert. Bei dem Versuch der Verkapselung von Geschmacksstoff konnte festgestellt werden, das sich die Proben bezuglich ihres Verkapselungsverhaltens betrachtlich von-einander unterschieden.

Effect of steam-hydrothermal treatment (SHTT) on functional properties of cassava was studied using fresh tubers of cultivar Malayan-4 (M-4). Fresh slices were steam-processed for 5, 10 and 20 min at atmospheric pressure. Plain-dried samples were also prepared for comparison. SHTT samples were found to have higher rehydration capacity, equilibrium moisture content by soaking (EMC-S), and sedimentation volume at room temperature (28–30° C). These samples also showed a lower amylose content than plain-dried samples. Electrolytes like sodium chloride, sodium sulphate and sodium phosphate at 1–0 N concentration changed the sedimentation volume, especially of SHTT sample:. Paste stability of steam-processed samples at cooking temperature (95° C) was relatively higher than plain-dried ones. Among the three SHTT samples, that steam-processed for 10 min showed the highest paste consistency and set-back ratio. X-ray diffraction pattern of flour prepared from SHTT samples indicated a clear shift from crystalline to a partially amorphous state. Infra-red spectra of cassava starch and flour samples were generally identical.