Effect of dynamic high-pressure treatments on the multi-level structure of starch macromolecule and their techno-functional properties: A review

Over the past decades, dynamic high-pressure treatment (DHPT) executed by high-pressure homogenization (HPH) or microfluidization (DHPM) technology has received humongous research attention for starch macromolecule modification. However, the studies on starch multi-level structure alterations by DHPT have received inadequate attention. Furthermore, no review comprehensively covers all aspects of DHPT, explicitly addressing the combined effects of both technologies (HPH or DHPM) on starch's structural and functional characteristics. Hence, this review focused on recent advancements concerning the influences of DHPT on the starch multi-level structure and techno-functional properties. Intense mechanical actions induced by DHPT, such as high shear and impact forces, hydrodynamic cavitation, instantaneous pressure drops, and turbulence, altered the multi-level structure of starch for a short duration. The DHPT reduces the starch molecular weight and degree of branching, destroys short-range ordered and long-range crystalline structure, and degrades lamellar structure, resulting in partial gelatinization of starch granules. These structural changes influenced their techno-functional properties like swelling power and solubility, freeze-thaw stability, emulsifying properties, retrogradation rate, thermal properties, rheological and pasting, and digestibility. Processing conditions such as pressure level, the number of passes, inlet temperature, chamber geometry used, starch types, and their concentration may influence the above changes. Moreover, dynamic high-pressure treatment could form starch-fatty acids/polyphenol complexes. Finally, we discuss the food system applications of DHPT-treated starches and flours, and some limitations.

Complexation temperature regulated the structure and digestibility of pea starch-gallic acid complexes during high pressure homogenization

Formation of starch-polyphenol complexes by high pressure homogenization (HPH) is widely used to reduce starch digestibility and delay the postprandial glycemic response, thereby benefiting obesity and associated metabolic diseases. This study investigated the effect of complexation temperature on multi-scale structures, physicochemical and digestive properties of pea starch-gallic acid (PS-GA) complexes during HPH process, while also elucidating the corresponding molecular mechanism regulating in vitro digestibility. The results demonstrated that elevating complexation temperature from 30 °C to 100 °C promoted the interaction between PS and GA and reached a peak complex index of 9.22 % at 90 °C through non-covalent binding. The enhanced interaction led to the formation of ordered multi-scale structures within PS-GA complexes, characterized by larger particles that exhibited greater thermal stability and elastic properties. Consequently, the PS-GA complexes exhibited substantially reduced digestion rates with the content of resistant starch increased from 28.50 % to 38.26 %. The potential molecular mechanism underlying how complexation temperature regulated digestibility of PS-GA complexes might be attributed to the synergistic effect of the physical barriers from newly ordered structure and inhibitory effect of GA against digestive enzymes. Overall, our findings contribute to the advancement of current knowledge regarding starch-polyphenol interactions and promote the development of functional starches with low postprandial glycemic responses.

Differences in the Chromogenic Effect of Corn Starch and Potato Starch on Paprika Red Pigment and Structural Characterisation

The present study aims to investigate the chromogenic effect and the interaction between starch-pigment complexes of corn starch (CS) and potato starch (PS) complexed with paprika red pigment. Compared to PS, CS showed 12.5 times higher adsorption capacity for paprika red pigment. Additionally, the a* value of CS-P (26.90 ± 0.23) was significantly higher than that of PS-P (22.45 ± 1.84), resulting in a corn starch-paprika red pigment complex (CS-P) with a more intense red colour. The addition of paprika red pigment significantly decreased the particle size and porosity of CS by 48.14 ± 5.29% and 17.01 ± 3.80%, respectively. Conversely, no significant impact on PS was observed. Additionally, the Fourier transform infrared (FT-IR) spectroscopy results revealed that the starch molecules and paprika red pigment were bound to each other through strong hydrogen bonds. X-diffraction (XRD) results indicated that the starch-paprika red pigment complexes have a V-shaped structure. Furthermore, the relative crystallinity of the complexes between starch and red pepper pigment showed an increasing trend, however, the relative crystallinity of CS increased significantly by 11.77 ± 0.99-49.21 ± 3.67%. Consequently, the CS-P colouring was good.

Effect of pressure treatment duration on the rheological characteristics of dry-heated alocasia starch in the presence of monosaccharide and disaccharide

The current work investigated the impact of different pressure processing times (5, 10, and 15 min) at 120 psi on the rheological behavior of a mixture of dry-heated Alocasia macrorrizhos starch with monosaccharide and disaccharide. Shear-thinning behavior was exhibited by the samples in steady shear evaluation and the highest viscosity was observed in the 15 min pressure treated samples. In the initial phase of amplitude sweep measurement, samples exhibited strain dependency but later they remain unaffected with applied deformation. The greater value of Storage modulus (G') than loss modulus (G″) (G' > G″) indicating the weak gel-like behavior. Increasing in pressure treatment duration enhanced the value of G' and G″ with applied frequency and found maximum at 15 min. In temperature sweep measurement the G', G″ as well as complex viscosity curves increased initially and then decreased after achieving peak temperature. However, the rheological parameters of the samples treated under long pressure processing time were found to be improved during temperature sweep measurements. The resulting extremely viscous, pressure-treated dry-heated Alocasia macrorrizhos starch-saccharides combination has a variety of uses in different pharmaceuticals as well as in food industries.

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.

Vigna subterranea (L.) Verdc Starch-Soluble Dietary Fibre Potential Nanocomposite: Thermal Behaviour, Morphology and Crystallinity

Bambara groundnut (BGN) starch-soluble dietary fibre nanocomposite (STASOL) was manufactured by grafting 1.95 g BGN soluble dietary fibre (BGN-SDF) onto 15 g BGN starch (BGNS). The particle sizes, functional groups, crystallinity, morphology and thermal properties of BGNS, BGN-SDF and STASOL were studied using a Zetasizer, Fourier transform infrared, X-ray diffraction, scanning electron microscope and differential scanning calorimetry, respectively. STASOL had a particle size and conductivity of 74.01 nm and −57.3 mV, respectively. BGN-SDF and STASOL were amorphous and BGNS was classified as type C starch, typical of legumes. The biopolymers had functional groups in the regions 2900–3600, 1600–1642, 900–1200 and 800–1300 cm−1, which could be attributed to the vibrational stretching of OH groups, vibration of OH groups in the non-crystalline region of starch, vibration of C-O, C-C and C-H-O bonds and the vibration of C-O and C-C bonds, respectively. BGNS had smooth, oval structures while BGN-SDF and STASOL exhibited irregular, polygonal morphologies. STASOL was the most thermally stable biopolymer, disintegrating at 293 °C, therefore suggesting that it would find use in high-temperature food applications such as baking.

In vitro digestibility and structural control of rice starch-unsaturated fatty acid complexes by high-pressure homogenization

This study emphasized on structural alteration of rice starch-unsaturated fatty acid complexes by adding trans-2-dodecaenoic acid (t12), trans-oleic acid (t18), cis-oleic acid (c18) and linoleic acid (loa) with different concentration under high-pressure homogenization treatment, and further illustrated the underlying mechanism of modulating digestibility. Results showed that the complex primarily presented as V6 or type IIa polymorph; complex index, content of ordered structure and thermal stability appeared to be positively correlated to the concentration of unsaturated fatty acids. t12 was too mobile to form single helix, leading to the formation of loose matrix; t18 fitted better within the cavity of starch than c18, and formed structural domain with higher compactness and thermal stability; Rloa had lower complex index but higher degree of short-range order, and tended to form alternating amorphous and crystalline structure. The digestibility was higher in the order of Rloa, Rt18, Rc18 and Rt12.

A review on structural, digestibility and physicochemical properties of legume starch-lipid complexes

There is a growing interest in alternative sources of starch for various industrial applications to cater for the increasing demand of starch, avoid the sole reliance on conventional sources such as corn and to prevent shortage of supply. Legume starches with high levels of amylose and high resistant starch contents are suitable alternatives. However, starch must be modified to overcome the shortcomings associated with native starches. The modification of starch with lipids results in the formation of inclusion complexes, called V-amylose complexes with improved physicochemical and functional properties and this category of modified starch is further regarded as clean-label. Clean-label ingredients are consumer and environmentally friendly and do not contain synthetic chemicals that may present food safety concerns. This review documents the current level of research on V-amylose complexes formed using legumes starches and outlines research gaps that could be explored for better utilisation of these legumes in the industry.

Morphology, structural, thermal and rheological properties of wheat starch–palmitic acid complexes prepared during steam cooking

This work aimed to determine the changes in the morphology, complexation degree, the structural, thermal, and rheological properties of starch–fatty acid complexes during steam cooking. In this study, wheat starch with certain water and palmitic acid contents were steamed for 0.5, 1, 1.5, 2, and 2.5 h. The complexing index (CI) first decreased and then progressively increased with the prolonging of steam cooking time. The decrease in CI was associated with the decomposition of the complex layer formed on the granule surface at 0.5 h of steam cooking. The interaction between wheat starch and palmitic acid led to the change of starch crystal type. Prolonging treatment time promoted thermal stability and structural order degree. The type I and IIa complexes reached saturation and fatty acids in the interstitial space between helices increased with excessive treatment times. Rheological behavior analysis showed that the viscoelasticity and deformation degree of samples decreased and increased, respectively, with increasing steam cooking time. Results showed that the thermostability and order degree of the complex layer were lower than those of samples with long treatment times and complexing was effective during steam cooking.

The present paper introduces the formation and characteristics of wheat starch–palmitic acid complexes during long-term steam cooking.