The influence of the type of substituents on the polymer dynamics of different regioselective 2-O-esters of starch using dielectric spectroscopy

The dielectric relaxation spectra of different regioselective 2-O-acyl-esters of amylomaize starch with a degree of substitution DS=1 were measured in an extended temperature (−135 to 0 °C) and frequency range (0.01 Hz to 3 MHz). For all starch esters, two relaxation processes were found, which are from the type of a secondary relaxation (constant activation energy). One process can be assigned to the local backbone motion of the polymer and the other one with the ester side group motion in position C2 at the anhydro glucose unit. The dynamic parameters of both relaxations were determined and compared. The double bond in the crotonoyl-ester side group has a little influence on both the segmental and the side group motion in relation to the butanoyl-ester. The bulky benzoyl-ester side group shows an inverse influence on the local chain dynamics than the alkyl-ester side group.     

The behaviour and susceptibility to degradation of high and low molecular weight barley β-glucan in wheat bread during baking and in vitro digestion

The behaviour and susceptibility to degradation of a high molecular weight (HMW) and low molecular weight (LMW) barley β-glucan in white bread during manufacture and in vitro digestion were investigated. The incorporation of both HMW and LMW barley β-glucan resulted in stiffer dough, lowered loaf volume and height compared to the control. The HMW barley β-glucan caused the greatest loss of dough and bread quality. Breads with HMW and LMW barley β-glucan exhibited attenuated reducing sugars release (RSR) over a 300 min in vitro digestion compared to the control, with generally no difference between the breads. HMW barley β-glucan was degraded during bread manufacture; however, degradation of the LMW barley β-glucan was not apparent. An in vitro digestion did not result in any further degradation of the molecular weight (MW) of either barley β-glucan.     

Some physical and nutritional characteristics of genetically modified potatoes varying in amylose/amylopectin ratios

Transgenically modified potatoes with a large spread in amylose/amylopectin ratios were analysed both as tubers and in the form of isolated starch. Different microscopic techniques were used to study starch granules and tuber tissue. Starch gelatinisation properties and recrystallisation of amylopectin and amylose were studied by differential scanning calorimetry. Starch bioavailability and resistant starch (RS) were evaluated using enzymatic in vitro procedures. Glycaemic indices (GI) were predicted from low molecular weight carbohydrates (LMWC) contents and the in vitro hydrolysis rate of the starch moiety. For many of the examined parameters, differences of varying magnitude were found between the potato lines, especially for high amylose lines. High amylose starch granules had irregular shapes and showed only a limited swelling. Moreover, contents of RS and recrystallised amylose were elevated. GI’s for the starch moiety were reduced, though elevated contents of LMWC caused a high over-all predicted GI.     

Amaranth starch-rich fraction properties modified by extrusion and fluidized bed heating

Today amaranth is a promising food source yet its technological properties are not well known. The modification of some properties of an amaranth starch-rich fraction by a controlled heating is studied. This fraction was obtained by the differential milling of Amaranthus cruentus grains.Tests were performed by both fluidized bed and extrusion heating, according to a factorial experimental design of two variables: temperature and moisture, at three levels 150-170-200 °C and 120-160-200 g/kg wb, respectively. Effects were evaluated by the ANOVA method. As responses, solubility and water absorption, amylographic and dynamic rheological properties, crystallinity, granular integrity and resistant starch content were evaluated. Flours obtained from samples heated by fluidized bed gave aqueous dispersions with high consistencies when cooked, and they had low solubility in water and preserved part of the starch crystalline structure. Flours obtained from extrusion-heated samples gave very high solubility in water but had lower consistency of the aqueous dispersions when cooked, and they showed a complete loss of the crystalline and granular structure.By applying each of the two heating processes, it was possible to modify, according to selected targets, the amaranth starch-rich fraction, what would allow to obtain pre-cooked amaranth flours with a wide range of hydration and rheological properties.     

淀粉的辐射降解及应用研究

介绍了＾６０Ｃｏγ射线对淀粉的辐射降解作用，初步研究了辐射剂量，剂量率对淀粉粘度的影响，测定了辐射降解淀粉中羧基的生成量，评价了淀粉辐照后的贮藏稳定性，粘度热稳定性，色泽变化等，简述了产品的应用情况。     

Biomaterials supported CdS nanocrystals

CdS quantum dot materials were prepared through a simple room temperature deposition of CdS nanocrystals on biomaterials including starch and chitosan. Materials obtained were found to contain differently distributed CdS nanocrystals on the surface of the biopolymers, making them potentially interesting for biomedical applications as contrast agents and/or in photocatalysis.     

酶法生产全糖的工艺与技术

介绍了全糖的组分、作用，以碎米为原料酶法生产全糖的工艺和技术要求。     

Effects of sodium dodecyl sulphate and sonication treatment on physicochemical properties of starch

Effects of sodium dodecyl sulphate (SDS) and sonication treatment on physicochemical properties of starch were studied on four types of starch, namely, corn, potato, mung bean, and sago. The SDS and sonication treatments caused a significant reduction of protein content for all the starches. The SDS treatment did not cause apparent damage on granular structure but sonication appeared to induce changes such as rough surface and fine fissures on starch granules. The combination of SDS and sonication increased amylose content for all starches. This could be attributed to the removal of surface protein by SDS and structural weakening by sonication which facilitated amylose leaching from swollen starch granule. The X-ray pattern for all starches remained unchanged after SDS treatment, suggesting no complexation of amylose–SDS had occurred. Combined SDS-sonication treatment increased swelling and solubility of corn, mung bean, and potato starch. The treated starches showed significant increase in peak viscosity with reduction in pasting temperature, except for potato starch. Results of the present study indicate the possibilities of exploring SDS and sonication treatments for starch modifications.     

ENZYMATIC HYDROLYSIS OF STARCH BY USING A SONIFIER

In the present study, the ultrasonication method was used to investigate the effect of ultrasonic energy on the hydrolysis of corn, rice, and wheat starch by using the alpha-amylase enzymes produced by Bacillus species and Bacillus licheniformis. The effects of sonifier operation variables such as duty cycle and acoustic power rate on the stability of alpha-amylase enzymes and hydrolysis degrees of three types of starches were investigated at a temperature of 40°C and pH 6.5. To determine the effect of temperature with sonication on the hydrolysis process, wheat starch hydrolysis experiments were also carried out at a temperature of 50°C. Then, the relation between duty cycle and enzyme stability during hydrolysis for each enzyme at 50°C was expressed by a zero-order inactivation model.     

Preparation of poly(acrylic acid)/starch hydrogel and its application for cadmium ion removal from aqueous solutions

In this paper, potassium bromate/thiourea dioxide redox system was used to initiate the graft copolymerization reaction of acrylic acid onto maize starch. The so obtained polyacrylic acid/starch graft copolymer was crosslinked by further treatment with alkaline epichlorohydrin to get three dimensional hydrogel. This crosslinked hydrogel was used for the removal of the heavy element, Cd²⁺ from its aqueous solution by adsorption. All factors which are expected to affect the adsorption process, like adsorbent concentration, immersion time, graft yield of the adsorbent, Cd²⁺ concentration and adsorption temperature were extensively studied and reported in the text. The study and investigations demonstrated that the adsorption efficiency is affected by the adsorbent graft yield and the adsorption medium temperature. In addition, on fitting the data obtained from the adsorption process, it was found that the adsorption obeys both Langmuir and Freundlich adsorption isotherms but the Langmuir isotherm shows better mathematical fitting for the equilibrium data than does Freundlich model, based on the higher R² value for the Langmuir isotherm.