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With respect of the partial molecular degradation of the starch polysaccharides, the impact of the acid-thinning process on the specific starch properties of two corn genotypes was investigated. A high amylose corn (HACS) and a waxy corn (WxCS) starch were hydrolyzed using HCl in the laboratory scale slurry process (40% w/w, 30 °C). The acid concentration (0.3, 0.6 and 0.9 M) as well as the hydrolysis time (4, 10 and 20 h) were graded systematically (experimental design) and the obtained modified starch genotypes characterized comprehensively. As revealed by scanning electron micoscopy (SEM), the supramolecular structure was preserved in general, and the carbohydrate solubilization was limited to about 2–3 %. Molecularly dispersed solutions were characterized by means of size exclusion chromatography-multi angle laser light scattering-differential refractive index detection (SEC-MALS-DRI). Both acid concentration and hydrolysis time reduced the molar mass (MM) of the starch [HACS: 4.4∙106 (native)…1.2∙106 g∙mol−1 (highest degree of degradation); WxCS: 49.7∙106 (native)…6.4∙106 g∙mol−1 (highest degree of degradation)], the amylose (AM) fraction as well as the amylopectin (AP) branch chain length systematically. Perceptible differences in dependence on starch variety were ascertained and discussed. The molecular properties of the investigated acid-thinned genotypes are selectively controllable with the hydrolysis process. The relationship between modification process, starch’s molecular state, and resulting functional properties was examined in the second part of the study.

The work presented here is concerned with the production of sugar from mixed juices that origin from both cane and beet. This is of interest because with the end of the regulation of the European sugar market in 2017 producers aim for higher utilization of their production sites. This can for example be achieved by co-processing of raw cane sugar and beet juice. Despite the abundant body of work concerning the colorants inclusion in either beet or cane sugar manufacturing practically no detailed information on this important parameter is available for mixed juices. The systematic study reported here reveals that colorants from different origin show a mutual suppression of their incorporation into the crystal. This is particularly surprising because these colorants are reported to follow specific incorporation mechanisms on different faces of the growing crystal. Further analysis reveals that the color contribution due to liquid inclusions, hence crystal imperfections, starts to increase only at high cane inclusion levels (80%), while the color effects of co-crystallization dominate and increase systematically with cane levels. Finally a model to forecast the color values of sugars crystallized from mixed juices is formulated.

Lecithin find a wide spread application in the food industry. The purpose of the work reported here was to systematically map the effects of some commercially available lecithins from different sources (soybean, sunflower, rapeseed), in their native state or hydrolysed form, on the crystallization behavior of model fat systems. To this end, systems based on palm oil as hard fat were studied. Next to macroscopic properties such as product hardness, the crystallization behaviour and the microstructure were studied as a function of time and temperature. Addition of the studied lecithin preparations had a significant influence on the hardness (p

In recent years, the interest in alternative cereals as pseudocereals has increased. The pseudocereal amaranth should be heated thermally before consumption. The purpose of this study was to investigate the textural and morphological change of Amaranthus caudatus during heat soaking below boiling temperature. Therefore, the effects of heat soaking at different temperatures (20, 50, 60, 70, 80 °C) and times (1, 5, 24 h) of Amaranthus caudatus were researched. A significant textural and morphological change of amaranth grains was found for samples soaked at temperatures ≥60 °C, due to gelatinization of starch. Overall, with an increase in temperature moisture content and water absorption increased, while the firmness of grains decreased. A similar trend was observed for color changes: higher temperatures lead to a darker grain color. SEM images of hydrothermally treated amaranth samples displayed microstructural changes of the embryo and perisperm, which explain the firmness decrease. The temperature had a higher influence on morphological and textural changes than soaking time. Especially higher temperatures significantly altered the texture and external appearance of the grains while soaking time had negligible effect.

The impact of the acid modification on the molecular properties of two corn starch genotypes (high amylose corn starch: HACS, amylose (AM) content about 70% w/w; waxy corn starch: WxCS, AM content

A commercial dietary fiber was mechanically modified by treating a suspension in a high pressure homogenizer. Different drying methods were applied prior to examining macroscopic and water binding properties. DSC experiments show that more water is bound non-freezable with increasing mechanical modification. Capillary suction method and centrifugation experiments confirm that the water binding capacity changes systematically on mechanical treatment. Rheological studies confirm that the modification has a profound effect on the physico-chemical properties of the fibers. Samples with higher water binding capacity result in gel-like structures relating to higher specific volumes or swelling and possibly increased mutual entanglement. The water binding is primarily linked to structural parameters, such as porosity and does not increase any further once additional mechanical treatment does not further lead to increased porosities. Electron microscope images support the experimental findings. Effects of mechanical treatment supersede the impacts of the different drying methods. However, more gentle drying methods such as freeze drying and water-ethanol-extraction-drying yield in general higher water binding capacities than spray drying and oven drying. The study documents that the profound effect of mechanical treatment on the water binding capacity of a cellulose based fibrous material is strongly related to the porosity of the dried samples.

Enzymatic neutralization is a recent research focus due to an increasing awareness of environmental problems caused by conventional oil refining. This study investigated the kinetics of enzymatic neutralization in crude Jatropha oil utilizing an immobilized lipase from Rhizomucor miehei . Free fatty acids, in particular oleic acid were esterified with glycerol. The reaction seems to follow a multisubstrate Ping Pong mechanism with competitive inhibition by the acyl acceptors (mono-, diacylglycerides and glycerol). Free fatty acid content did not affect lipase activity within the ranges investigated. The kinetic parameters were determined and showed that enzyme affinity is much higher to glycerol than to free fatty acids. These observations were supported by the fact that the optimum glycerol level is rather small while the reaction rate increases with increasing free fatty acid concentration.

The analysis of sucrose crystal size and shape modifications induced by the presence of dextran was key to this study. Therefore, evaporative crystallisation experiments using synthetic thick sucrose juices containing various contents of high molecular mass dextran (T2000) were performed. HPLC analysis of the dissolved sucrose crystals revealed that T2000 dextran gets incorporated into the sucrose crystal, indicating that dextran-related crystal size and shape modifications occur. For analysing the sucrose crystal size and shape distribution, static image analysis was implemented and compared to common sieve analysis as well as dynamic image analysis (Camsizer). All methods consistently indicate an increase of crystals with lower minimum and especially lower maximum feret diameters due to the presence of T2000 dextran. For the sucrose crystal shape analysis, average values and relative frequency distributions were evaluated. For more detail, the shape data were further processed using a crystal size-dependent evaluation. Thereby, it was found that cube-shaped crystals, elongated needle-shaped crystals and agglomerates can be related to the presence of dextran. The data suggest that the occurrence of the three dextran-related shapes depend on the dextran content present and also relate to certain sucrose crystal sizes. This way, cube-shaped crystals could be related to small-sized crystals, predominantly occurring at lower dextran contents. Agglomeration and distinct elongation were found to be related to mid- and especially large-sized crystals. The latter two, especially distinct elongation, seem to increasingly occur when higher dextran contents were present.

The structure of many food products is based on networks of crystalline triacylglycerol (TAG) hardstock. These contain high levels of saturated fatty acids, which are among the factors contributing to cardiovascular diseases. Therefore it would be desirable to have alternative routes to structure edible oils. This review starts with general structuring concepts and building blocks which can be found in organic solvents. Subsequently it focuses on the field of edible oil structuring. Among the alternative structuring agents that have received attention in recent years are mono- and diglycerides, fatty acids, fatty alcohols, waxes, wax esters, sorbitan esters, and phytosterols. It is found that the most efficient structuring agents form small, preferably non-spherical particles. Mixing of components often provides superior structuring over use of pure components. Straightforward screening of pure components might be feasible. However, the number of options provided by mixing requires guided screening, for which understanding of the underlying mechanisms is essential. Analytical methods helping to characterise oil structuring and elucidate the structuring mechanisms are discussed.

Edible fats and oils are complex mixtures containing a wide range of (classes of) compounds. The most important group of compounds are the triglycerides (triacylglycerides, TAGs). Because of the large number of possible fatty acid combinations, an enormous number of TAGs is possible. In the present feasibility study, the applicability of different modes of comprehensive two-dimensional LCXGC for detailed oil and fat analysis is evaluated. Comprehensive LCXGC was found to be an extremely powerful analytical method for the analysis of complex TAG samples. Using the new comprehensive set-ups, TAGs can be separated according to two independent parameters: carbon number vs. number of double bonds, or fatty acid composition vs. number of double bonds. The information content of comprehensive separations by far exceeds that of the current generation of analytical methods. The quantitative results of the separations show a good agreement with data obtained from standard analytical methods. The comprehensive methods studied can also be used for fingerprinting of oil samples, as well as for the analysis of target compounds or compound groups. Highly detailed separations of olive oil samples were obtained. Zooming in on one region of the chromatogram allowed reliable analysis of wax esters without interferences of sterol esters.

Phytosterol esters are known for their blood cholesterol lowering effect and have consequently been incorporated into vegetable oil table-spread products. In furtherance to gaining knowledge about these materials in a fat-blend environment, the current work describes the phase-diagram based thermal characteristics of a series of β-sitosterol alkyl-ester homologues prepared as binary mixtures and observed using differential scanning calorimetry. A scanning speed of 10 K min−1 was chosen and, whilst not representing true equilibrium conditions, was more indicative of the likely dynamic melting or cooling conditions found in a fat-blend product during processing. The thermal behaviours presented reflect therefore this concept. Long-chain saturated esters showed ideal solubility behaviour of immiscible solids. In contrast, the shorter-chain homologues produced complex and dynamic phase behaviours, including some mesophase development. In all cases, supercooling was observed on cooling due to retarded crystallisation, which could equally result in two crystal conformations, depending on the actual composition.

In this paper experimental results on vapour–liquid and solid–fluid phase equilibria for three types of ternary mixtures are reported. The ternary systems studied were methane+water+hexadecane, methane+propane+tetracosane, and methane+docosane+tetracosane. The influence of an excess water phase on the vapour–liquid critical curve of the methane+hexadecane system is determined and found to be negligible in a temperature range from 290 to 350 K. The effect of the addition of propane on the phase behaviour of two mixtures of methane+tetracosane was studied. On addition of propane (xC3=0.15) a decrease of the bubble- and dew-point pressures of up to 40 MPa was observed. Also a shift of the solid+fluid/fluid)boundary curve towards lower temperatures at constant pressure of approximately 6 K was found. For 20 mixtures of the ternary system methane+docosane+tetracosane, the solid–fluid and vapour–liquid equilibria were studied at temperatures up to 350 K and at pressures up to 200 MPa. The different isobaric solid-solubility curves show discontinuities at a relative solute mole fraction of tetracosane of 0.15 and 0.5. This most likely indicates the presence of different mixed crystal structures in the solid phases precipitating from the ternary mixtures at high pressures.

In this paper, experimental data on the high-pressure phase behaviour of the systems methane + phenanthrene and methane + 1-phenyldodecane are presented. For both systems vapour-liquid, solid-fluid, and solid-liquid-vapour equilibrium data were determined. The experiments were carried out for various mixtures covering almost the whole composition range. The temperature range investigated was from 360 to 460 K for the methane + phenanthrene system and from 260 to 400 K for the methane + 1-phenyldodecane system. The maximum pressures exerted on the samples were dependent on the equipment used, either 200 or 400 MPa. The second critical endpoint (s + 1 = g), which is the pressure maximum of the three-phase curve (solid hydrocarbon + liquid + vapour), is, for the methane + phenanthrene system, located at a temperature T = 403.3 ± 0.4 K, a pressure p = 358.9 ± 1.5 MPa, and a mole fraction of phenanthrene in the critical fluid phase x = 0.126 ± 0.009. The coordinates of the second critical endpoint of the methane + 1-phenyldodecane system were found to be T = 277.1 ± 0.4 K, p = 148.0 ± 0.6 MPa, and for the mole fraction of 1-phenyldodecane in the critical fluid phase x = 0.076 ± 0.005.

Experimental vapour-liquid, solid-fluid, and solid-liquid-vapour equilibrium data of the binary system (methane + tetracosane) in the temperature range 315–450 K and for pressures up to 200 MPa are presented. The experiments were carried out for various mixtures with compositions ranging from almost pure methane to pure tetracosane. It was found that the (solid α-to-solidβ) transition of pure tetracosane has hardly any influence on the shape of the (solid + fluid/fluid) boundary curves and the three-phase equilibrium curve (solid tetracosane + liquid + vapour) of the binary system. The second critical endpoint of the three-phase curve (sC24 + 1 = g), where solid tetracosane is in equilibrium with a critical fluid phase was located at a temperature of T = (322.60 ± 0.25)K, a pressure of p = (104.7 ± 0.4)MPa, and a mole fraction of tetracosane in the critical fluid phase of xC24 = (0.041 ± 0.003).

Experimental results for the various phase equilibria of {(1 −x)CH4+xCH3(CH2)18CH3} are presented. (Vapour + liquid) equilibria were measured for 26 different mixtures covering almost the whole composition range. The temperature varied between 303 K and 370 K. (Solid + liquid) and (solid + vapour) equilibrium measurements were performed for 20 different mixtures. The pressures applied did not exceed 100 MPa. On the basis of the primary experimental two-phase equilibrium results, the course of the three-phase curve (solid eicosane + liquid + vapour) could be derived. The second critical endpoint, where solid eicosane is in equilibrium with a critical fluid phase (SC20+ 1 = g), was found at a temperatureT= (307.37 ± 0.15) K, a pressurep= (89.0 ± 0.25) MPa, and a mole fraction in the critical fluid phase ofx= (0.049 ± 0.0012).