Gelatinization kinetics of rice starch studied by non-isothermal calorimetric technique: influence of extraction method, water concentration and heating rate

Effects of Porphyra haitanensis polysaccharides on gelatinization and gelatinization kinetics of starches with different crystal types

The effects of Porphyra haitanensis polysaccharide (PHP) on the gelatinization and gelatinization kinetics of corn starch (CS), potato starch (PS) and lotus seed starch (LS) were studied. The gelatinization, rheological and thermal enthalpy properties of the samples were measured by a rapid viscosity analyzer (RVA), a rheometer, and a differential scanning calorimeter (DSC), respectively. And the kinetic equations were further established. RVA confirmed that the addition of 0.4 %, 0.8 % and 1.2 % PHP elevated the gelatinization viscosity of CS and LS but decreased that of the PS, and also elevated the thermal balance of CS, PS, and LS, especially PS (The breakdown viscosity was decreased to 363.00 ± 6.08, 370.00 ± 1.15, and 362.00 ± 0.58, respectively). And the rheometer indicated that the addition of 0.4 %, 0.8 % and 1.2 % PHP improved the apparent viscosity of CS, PS and LS, especially PS (The consistency coefficient was increased to 18.26 ± 0.02, 21.71 ± 0.04, and 23.26 ± 0.01, respectively). Eventually, DSC displayed that the addition of 0.4 %, 0.8 % and 1.2 % PHP extended the gelatinization temperature and enthalpy of CS, PS, and LS, especially PS. Among them, the gelatinization temperature (63.40 ± 0.03, 70.26 ± 0.02 and 74.61 ± 0.01, respectively) and the gelatinization enthalpy (1.55 ± 0.01) of PS increased the most with 1.2 % PHP. Moreover, gelatinization kinetics displayed that the addition of 0.4 %, 0.8 % and 1.2 % PHP decreased the rate constants of CS, PS, and LS and accelerated the activation energies of CS (666.37 ± 4.23, 623.89 ± 4.21 and 558.39 ± 2.35, respectively) and PS (752.53 ± 4.13, 699.61 ± 3.78 and 662.15 ± 4.52, respectively) while reducing that of the LS (938.87 ± 3.38, 669.98 ± 4.61 and 491.48 ± 4.29, respectively). Therefore, the addition of PHP at all concentrations inhibited the gelatinization procedure of CS and PS but promoted that of the LS. This study provided a theoretical basis for the creation of new products based on PHP and starch.

Application of Computational Fluid Dynamics (CFD) in the Deposition Process and Printability Assessment of 3D Printing Using Rice Paste

Computational fluid dynamics (CFD) was utilized to investigate the deposition process and printability of rice paste. The rheological and preliminary printing studies showed that paste formed from rice to water ratio (100:80) is suitable for 3D printing (3DP). Controlling the ambient temperature at 47±5 °C also contributed to improving the printed sample’s structural stability. The viscoelastic simulation indicated that the nozzle diameter influenced the flow properties of the printed material. As the nozzle diameter decreased (1.2 mm to 0.8 mm), the die swell ratio increased (13.7 to 15.15%). The rise in the swell ratio was a result of the increasing pressure gradient at the nozzle exit (5.48×106 Pa to 1.53×107 Pa). The additive simulation showed that the nozzle diameter affected both the residual stress and overall deformation of the sample. CFD analysis, therefore, demonstrates a significant advantage in optimizing the operating conditions for printing rice paste.

Effect of Cryostructuring Treatment on Some Properties of Xanthan and Karaya Cryogels for Food Applications

Cryogels are novel materials because the manufacturing process known as cryostructuring allows biopolymers to change their properties as a result of repeated controlled freeze-thaw cycles. Hydrogels of xanthan and karaya gums were evaluated after undergoing up to four controlled freeze-thaw cycles in indirect contact with liquid nitrogen (up to -150 °C) to form cryogels. Changes in structural, molecular, rheological, and thermal properties were evaluated and compared to those of their respective hydrogels. Samples were also analyzed by Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy with Attenuated Total Reflection (FTIR-ATR), Rotational Rheology (RR), Modulated Differential Scanning Calorimetry (MDSC) and zeta potential (ζ). In general, significant differences (p < 0.05) between the numbers of freeze-thaw cycles were found. Karaya cryogels were not stable to repeated cycles of cryostructuring such as the three-cycle xanthan cryogel, which has the best structural order (95.55%), molecular interactions, and thermal stability, which allows the generation of a novel material with improved thermal and structural properties that can be used as an alternative in food preservation.

Trypsin and chymotrypsin are necessary for in vitro enzymatic digestion of rice starch

An appropriate in vitro starch digestion model is necessary to comparatively evaluate the digestibility of starch samples and to help predict the in vivo glycemic responses of starchy foods.

Retrogradation enthalpy does not always reflect the retrogradation behavior of gelatinized starch

Starch retrogradation is a term used to define the process in which gelatinized starch undergoes a disorder-to-order transition. A thorough understanding of starch retrogradation behavior plays an important role in maintaining the quality of starchy foods during storage. By means of DSC, we have demonstrated for the first time that at low water contents, the enthalpy change of retrograded starch is higher than that of native starch. In terms of FTIR and Raman spectroscopic results, we showed that the molecular order of reheated retrograded starch samples is lower than that of DSC gelatinized starch. These findings have led us to conclude that enthalpy change of retrograded starch at low water contents involves the melting of recrystallized starch during storage and residual starch crystallites after DSC gelatinization, and that the endothermic transition of retrograded starch gels at low water contents does not fully represent the retrogradation behavior of starch. Very low or high water contents do not favor the occurrence of starch retrogradation.

Molecular disassembly of rice and lotus starches during thermal processing and its effect on starch digestibility

The molecular disassembly of starch during thermal processing is a major determinant for the susceptibility of starch to enzymatic digestion.

Phase transitions of pea starch over a wide range of water content

The phase transitions of pea starch over a wide range of water content were investigated by differential scanning calorimetry (DSC). Swelling of starch granules increased progressively with increasing water content. The main endotherm G broadened progressively with increasing water content up to 94.5 wt % (water:starch ratio 15:1), above which it became too broad to define. The corresponding peak and conclusion temperatures and enthalpy change increased with increasing water content. Scanning electron microscopy (SEM) showed that, at a water:starch ratio of 2:1 (water content of 70.7 wt %), starch granules only swelled partially with discernible granular contours still clearly evident. The results of swelling power tests and SEM images revealed that the endotherm G obtained at a water:starch ratio of 2:1 represented only partial swelling of starch granules. The transition from a narrow to broad endotherm G was interpreted to reflect the thermal transition behavior progressing from limited swelling to maximum swelling and then partial dissolution and leaching of starch polymers from the granules.

State diagrams for improving processing and storage of foods, biological materials, and pharmaceuticals (IUPAC Technical Report)

Supplemented temperature/composition phase diagrams include the non-equilibrium glass-transition temperature (Tg) curve and equilibrium ice-melting and solubility curves. The inclusion of the non-equilibrium curve allows one to establish relationships with the time coordinate and, thus, with the dynamic behavior of systems, provided that the thermal history of such systems is known. The objective of this report is to contribute to the potential applications of supplemented state diagrams for aqueous glass-formers, in order to describe the influence of water content, nature of vitrifying agents, and temperature on the physico-chemical properties of foods and biological and pharmaceutical products. These data are helpful to develop formulations, processing strategies, or storage procedures in order to optimize the stability of food ingredients and pharmaceutical formulations. Reported experimental data on phase and state transitions for several food and pharmaceutical systems were analyzed. Some methodological aspects and the effect of phase and state transitions on the main potential chemical reactions that can alter those systems during processing and/or storage are discussed.