Rheological and textural studies of fresh and freeze-thawed native sago starch–sugar gels. I. Optimisation using response surface methodology

Influence of disaccharide and monosaccharide on the rheological behavior of dry-heated alocasia starch under high pressure assisted treatment

High viscous products made with starch are of great scientific interest in the food, pharmaceutical, and cosmetic industries because they can be used to make creams and gels, as well as functional foods and nutritional products. But, obtaining a good quality highly viscous materials represent a technological challenge. In this present study, the effect of high-pressure treatment at 120 psi for different time interval on the mixture of dry-heated alocasia starch in presence of monosaccharide and disaccharide was studied. A flow measurement test on the samples revealed their shear-thinning behavior. With 15 min of high-pressure processing time, the dry-heated starch and saccharide mixtures displayed the highest viscosity. The dynamic viscoelasticity measurement showed that the storage and loss modulus was enhanced significantly after high-pressure treatment, and all pressure-treated samples showed a gel-like structure (G/>G//). In temperature sweep measurement, the rheological profile of storage modulus, loss modulus, and complex viscosity exhibited a two-stage pattern, i.e., first increased, then decreased, and their values were enhanced significantly after pressure treatment. The resultant highly viscous dry-heated starch and saccharide system have various functionalities in diverse food and pharmaceutical products.

Controlled release of curcumin from gelatin hydrogels by the molecular-weight modulation of an oxidized dextran cross-linker

Controlled drug delivery could minimize side effects while maintaining a high local dose. Herein, a hydrogel carrier was prepared by forming dynamic imine bonds between gelatin and oxidized dextran (ODex) of different molecular weights (Mw = 10, 70, and 150 kDa). The morphology, thermal stability, rheology, mechanical properties, and swelling properties of the hydrogels and the controlled release of curcumin were characterized. When dextran with a higher Mw was used, the ODex contained more aldehyde groups, which led to a higher degree of cross-linking, considerably shorter gel time, decreased hydrogel porosity, and well-controlled release of curcumin. In addition, the cross-linked hydrogels exhibited not only high thermal stability but also excellent mechanical properties. However, because the matrix was hydrophilic, the swelling properties of the hydrogels were not significantly affected by the Mw of ODex. These observations suggest an approach for designing nutrient delivery carriers with improved controlled release.

Modification of Kutki millet (Panicum sumatrense) starch properties by the addition of amino acids for the preparation of hydrogels and its characterization

Starch is a biopolymer containing hydrophilic groups and is used in hydrogels preparation. Amino acids are multifunctional monomers of proteins that can be used as a cross linker to modify the starch by incorporating new functional groups into its chains. In this study, the Kutki millet starch was isolated and modified with lysine (positively charged), aspartic acid (negatively charged), and threonine (neutral) at varying pH levels. These modified starches were characterized for their various functional, structural, pasting, and textural properties. Hydrogels prepared from Lys9-KMS, Thr9-KMS, and AA11-KMS, possessing less adhesiveness, strong integrity, and hardness were then characterized for their XRD and morphological characterization. The principal component analysis (PCA) biplot showed that the samples modified at higher pH levels are positively correlated with the textural properties, swelling power and amylose content (I and IV quadrants), than those modified at lower pH. It may be inferred that starch modified with amino acid at higher pH have good textural properties than those at lower pH. Results of the overall investigation indicated that among these three amino acids, lysine could be a better cross linker for modification of Kutki millet starch and preparation of their gels for the delivery of nutraceuticals.

Rheological, textural and emulsifying properties of an exopolysaccharide produced by Mesorhizobium loti grown on a crude glycerol-based medium

In the present study, a new extracellular polysaccharide (EPS-M816) was obtained during the growth of Mesorhizobium loti Semia 816 on a crude glycerol-based medium. EPS-M816 precipitate mainly consisted of carbohydrates (82.54%) and proteins (11.31%), and the weight average molecular weight was estimated at 1.646 × 10⁶ Da. The biopolymer was characterized by FT-IR and NMR spectroscopy, and was found to have typical functional groups of other rhizobial polysaccharides. Furthermore, the rheological and emulsifying properties were investigated. The EPS-M816 solution (1.0% w/v) showed typical pseudoplastic non-Newtonian fluid behavior, and the addition of sodium and potassium chloride (1 mol L^-1) increased the apparent viscosity. Regarding its emulsification activity, EPS-M816 formed emulsions with different food-grade vegetable oils (soybean, rice, canola, sunflower and corn oils), showing emulsification index values over 65% in 24 h, indicative of strong emulsion-stabilizing capacity. The biopolymer was able to form gels with texture parameters similar to those reported for xanthan gum and low syneresis. Overall, these results suggest that EPS-M816 is a good candidate for application in the food, cosmetics and pharmaceutical industries as a thickening, gelling, stabilizing and emulsifying agent.

A comparison of the effects of heat moisture treatment (HMT) on rheological properties and amylopectin structure in sago (Metroxylon sago) and arenga (Arenga pinnata) starches

The objective of this study was to study and compare the impact of HMT on rheology and textural properties observed between sago and arenga starces, and then related to structural change of amylopectin. The HMT were conducted using the autoclaving method at 20% moisture content and heated to 120 C for 60 min for sago and 90 min for arenga starch as optimum condition. The HMT shifted gelatinization temperature higher and reduced the enthalpy of both starches. The HMT sago starch paste exhibited an exceptionally strong shear thinning behavior as shown by a rapid decrease of viscosity and an increase of shear rate. The HMT clearly made the texture of starch gels more fragile compared to their native form and reduced their breaking point to a lower strain. The HMT effect on the rheological properties and texture of the sago starch was greater than the changes observed with the arenga starch. Major changes in rheological properties after HMT was not followed by changes in amylopectin structure. The HMT process did not significantly affect the amylopectin chain-length distribution in Arenga starch. In the sago starch, HMT affect to long chain amylopectin with DP ≥ 37. The HMT effect on rheology and textural properties was higher in sago starch than arenga starch. This study demonstrated that long chain amylopectin with DP ≥ 37 plays an important role in contributing to the rheological change caused by the HMT.

Addition of Whey Protein in Bread-Making: Textural Parameters and Antioxidant Potential of Leavened and Unleavened Bread

The purpose of the study was to determine (1) whether baking process (a unit operation) – applied to produce leavened (LFB) and unleavened bread (UFB) – modifies the bioactivity of whey protein (WP) added in these portions and (2) how whey protein can change the textural parameters of these formulations. Reducing power activity (antioxidant potential) in food matrix was evaluated using phosphomolybdenum method. Textural parameters – hardness, cohesiveness, springiness, resilience, chewiness and gumminess – were carried out on a texture analyzer. In addition, this study demonstrated that the biofunctionality of whey protein was maintained in UFB 10 % WP. Nonetheless, this same formulation showed high values of textural parameters (hardness, chewiness and gumminess). Regarding the LFB formulations, the antioxidant potential was restricted after baking process in LFB 10 % WP. In conclusion, addition of bioactive additive in food matrix may not be sufficient to turn it into a functional food considering the effect of unit operations on bioactivity of some potential additives.

Extraction and application of starch-based coagulants from sago trunk for semi-aerobic landfill leachate treatment

Malaysia is one of the highest starch producers. In this study, sago starch was utilized as a natural coagulant aid to reduce the dosage of aluminum-based coagulant in leachate treatment. The potential of native sago trunk starch (NSTS) and commercial sago starch (CSS) was evaluated as sole coagulant and coagulant aid in the presence of polyaluminum chloride (PACl) in the removal of color, suspended solids (SS), NH3-N, turbidity, chemical oxygen demand, organic UV254, Cd, and Ni. Leachate was sampled from Pulau Burung Landfill Site, one of the semi-aerobic landfills in Malaysia. The optimum dosage for PACl in the presence of NSTS or CSS as coagulant aid was reduced from 3100 to 2000 mg/L. In the presence of 2000 mg/L PACl with 6000 mg/L NSTS and 2000 mg/L PACl with 5000 mg/L CSS, the removal performance for color, SS, and turbidity are 94.7, 99.2, and 98.9%, respectively. Similar results were obtained with the use of 3100 mg/L PACl alone. Therefore, CSS and NSTS can be used as coagulant aid.