Effect of potassium and magnesium treatment on physicochemical and rheological properties of potato, corn and spelt starches and on thermal generation of free radicals

Effect of cation valence on the retrogradation, gelatinization and gel characteristics of maize starch

This study aimed to examine the impact of trivalent, divalent, or monovalent cations dissolving into water and being mixed with maize starch to influence its retrogradation, gelatinization, and gel characteristics. The result of the analysis using a differential scanning calorimeter showed that all cations raised the peak of gelatinization temperature of maize starch, especially Al3+ or Fe3+, while trivalent cations reduced the enthalpy. The result of the analysis using a rapid viscosity analyzer showed that trivalent cation caused lower trough viscosity, final viscosity, and pasting temperature but higher breakdown viscosity of maize starch than monovalent or divalent cations. Confocal laser scanning microscopy showed that the cation promoted the destruction of gelatinized maize starch granules, especially Zn2+, Fe3+, or Al3+. Additionally, trivalent Fe3+ or Al3+ caused higher gel strength of maize starch. Generally, the cation with higher valence changed more retrogradation, gelatinization, and gel characteristics of maize starch.

Metal ion-mediated modulation of morphology, physicochemical properties, and digestibility of type 3 resistant starch microparticle

Short-chain glucan (SCG) derived from debranched amylopectin has emerged as a promising candidate for the production of resistant starch particle (RSP) due to its controllable self-assembly features. Here, we investigated the effect of metal cations with different valencies and concentrations on the morphology, physicochemical properties, and digestibility of RSP formed by the self-assembly of SCG. The effect of cations on the formation of RSP followed the valency in the following order: Na⁺, Ka⁺, Mg²⁺, Ca²⁺, Fe³⁺, and Al³⁺, of which 10 mM trivalent cations increased the particle size of RSP over 2 μm and considerably decreased the crystallinity by 49.5 % ~ 50.9 %, which were significantly different from that of mono- and divalent ones. Importantly, RSP formed with divalent cations switched the surface charge from -18.6 mV to 12.9 mV, which significantly increased the RS level, indicating that metal cations would be useful for regulating physicochemical properties and digestibility of RSP.

The effects of pH and iron ions on the mechanical properties of pea starch hydrogels

In this study, the network strength of starch hydrogels was improved by adjusting the pH value (3-11.5) and adding iron ions (Fe3+), and the mechanical properties and swelling properties of the hydrogels were improved. The complex modulus of the starch hydrogel with a pH value of 11.5 and containing Fe3+ was above 3400 Pa. SEM showed that the hydrogel structure became more compact with the increase of pH value. In addition, the hardness of the hydrogel increased from 50.29 g at pH 3.0 to 215.1 g at pH 11.5, while the addition of 0.5 mol/L Fe3+ at pH 11.5 promoted a further hardness increase to 301.8 g. Moreover, the swelling rate of the hydrogel decreased from 670.2 % at pH 7.0 to 464.4 % at pH 11.5, and the addition of 0.5 mol/L Fe3+ further decreased the swelling rate to 191.8 %. Overall, the results indicate that the mechanical properties of starch hydrogels can be improved by making simple adjustments to the pH and the iron ion concentrations.

Rheological and technological characterization of red rice modified starch and jaboticaba peel powder mixtures

Properties of modified starch and its interaction with functional raw materials are of great interest to the food industry. Thus, this study aimed to evaluate the rheological and technological characterization of starches modified by the action of the enzymes α-amylase and amyloglucosidase and their mixtures with jaboticaba peel powder. The parameters of firmness, gumminess, and final viscosity of starches paste increased, and the tendency to setback was reduced with the addition of jaboticaba peel powder. Starches and mixtures presented shear-thinning behavior. The addition of jaboticaba peel powder to starches increased water, oil, and milk absorption capacity, while syneresis remained stable over the storage period. The addition of jaboticaba peel powder had a positive effect on native and modified starches' rheological and technological properties, qualifying it as an alternative for developing new functional food products.

A review on the physicochemical properties of starches modified by microwave alone and in combination with other methods

Native starches are unsuitable for most industrial applications. Therefore, they are modified to improve their application in the industry. Starch may be modified using enzymatic, genetic, chemical, and physical methods. Due to the demand for safe foods by consumers, researchers are focusing on the use of cheap, safe and environmentally friendly methods such as the use of physical means for starch modification. Microwave heating of starch is a promising physical method for starch modification due to its advantages such as homogeneous operation throughout the whole sample volume, shorter processing time, greater penetration depth and better product quality. More recently, the use of synergistic methods for starch modification is being encouraged because they confer better functionality on starch than single methods. This review summarizes the present knowledge on the structure and physicochemical properties of starches from different botanical origins modified using microwave heating alone and in combination with other starch modification methods.

Magnesium ion impregnation in potato slices to improve cell integrity and reduce oil absorption in potato chips during frying

The effect of structural alteration of potato tissues by using divalent ions on oil uptake, texture, and color of deep-fat fried potato chips. The structure modification was achieved by sonication-assisted vacuum impregnation (SVI), with varying sonication times and soaking concentrations of MgCl₂.

SVI pretreated (sonicated by 50 min in a 15K magnesium solution) potato chips had 20% and 41% less oil content than the NSVI and control samples, respectively; and absorbed 29% more magnesium than the NSVI samples. The SVI pretreatment significantly affected product texture, color, shrinkage, and porosity.

Potato chips treated with combined MgCl₂ and CaCl₂ received a significant higher score than the other two treatments because of the improved sample's texture (crispness).

Microscopic analysis of SEM images showed a well-intact cellular structure and thicker middle lamelae after SVI treatment compared to the control samples.

Transformations and functional role of starch during potato crisp making: A review

Potato chips are a major product in the savory snack market and are consumed worldwide because of their enjoyable and distinctive organoleptic properties. They are conventionally produced by deep-frying thin slices of fresh potato. In contrast, potato crisps are manufactured from dried potato derivatives such as potato flakes (PFs). Their production is reviewed in this manuscript and requires the formation of dough based on hydrated PFs. Expansion of the dough during deep-frying provides the crisps with their desired crunchy texture. As part of an overall trend, the consumer search for calorie-reduced food products has also stimulated research to lower oil uptake during crisp production. However, minimizing oil absorption without losing the characteristic palatability of deep-fried products is challenging and requires fundamental knowledge on factors determining product texture and oil absorption. The transformations and functional role of starch, potato's main constituent, during crisp making are key in this respect and are reviewed here.

Physicochemical properties of potato starches manufactured in Hokkaido factories

Potato starch is an important agricultural product in Hokkaido, the northernmost island of Japan, with output of around 0.18 million tons/year. The present investigation was conducted to evaluate the physicochemical properties of potato starch samples manufactured in 10 factories in Hokkaido. The starch samples were analyzed for pasting properties by rapid visco analyzer (RVA), gelatinization properties by differential scanning calorimetry (DSC), color components, and minerals, amylose, and resistant starch (RS) contents. The phosphorus and potassium contents of potato starches averaged 746 ppm and 681 ppm, ranging from 669 to 835 ppm and from 481 to 803 ppm, respectively. Relatively wide ranges were noted in the contents of sodium (35-134 ppm), magnesium (50-121 ppm), and calcium (34-164 ppm). RVA analysis revealed clear differences in peak viscosity (PV) and breakdown (BD) among starch samples examined. Higher contents of divalent cations, magnesium, and calcium, were associated with lower values of PV and BD, whereas the phosphorus content did not affect PV and BD. The differences in amylose content, DSC gelatinization properties and color components as well as RS content in raw starch were not large.

Cracking and fracture properties of potato (Solanum tuberosum L.) tubers and their relation to dry matter, starch, and mineral distribution

BACKGROUND

Potato disorders lead to a significant reduction in the yield and quality of marketable tubers. Thumbnail cracks are physiological tuber skin disorders that can significantly affect the tuber's appearance and, hence, the overall quality. The aim of this study was to characterize fracture properties of the tuber skin. Knowledge of the physiological reasons that influence the resistance of potato tubers to mechanical impacts and thus to cracking and fracturing is limited. Tuber dry matter (DM) and starch content were found to correlate with the rheological properties of tubers, which, in turn, could affect the resistance of the tubers to cracking and fracturing. Moreover, divalent cations, such as calcium (Ca) and magnesium (Mg), and their distribution in the tuber can affect the tuber's resistance to mechanical impacts via cell-wall stabilizing properties.

RESULTS

Tubers with higher DM, starch, and Ca concentrations exhibited the highest resistance to mechanical impacts.

CONCLUSIONS

The reason for the increased resistance of tubers with higher DM and starch concentrations to mechanical impacts is assumed to be related to a certain cell structure of these tubers, which is why considerable force is needed to damage the cell structures. The relation between higher Ca concentrations and an improved resistance of tubers to mechanical impacts is assumed to be connected with the role of Ca in linking cell-wall polymers and thus stabilizing the cell wall. © 2018 Society of Chemical Industry.

Preparation of iron-fortified potato starch and its properties

Iron fortification was applied to commercial potato starch by immersion in different concentrations of ferrous sulfate (FeSO₄) aqueous solutions. To determine the impact of iron fortification on the properties of potato starch, all of the starches obtained through the process mentioned above were analyzed for their pasting properties, color, gelatinization properties, and resistant starch content. Results indicated that the iron content markedly increased from 16 to 890 ppm when the potato starch was treated with a FeSO₄ aqueous solution. During iron fortification, pasting properties markedly changed. Peak viscosity and breakdown decreased while peak viscosity temperature increased with iron fortification. Iron fortification caused a little reduced whiteness (slightly lower L*-value) and enhanced yellowish color (higher b*-value). In contrast, iron fortification had little influence on the gelatinization temperature and enthalpy. Moreover, no significant change in the resistant starch content was observed due to iron fortification.

Preparation of calcium- and magnesium-fortified potato starches with altered pasting properties

Calcium- and magnesium-fortified potato starches were prepared by immersion in various concentrations of CaCl2 and MgCl2 aqueous solutions, respectively. The pasting properties, i.e., peak viscosity and breakdown, of all the starches obtained above were analyzed using a Rapid Visco Analyzer. Furthermore, the gelatinization properties and in vitro digestibility of the representative calcium- and magnesium-fortified starches were tested. The maximum calcium content of the fortified potato starches was as high as 686 ppm with the addition of a high-concentration CaCl2 solution, while the calcium content of the control potato starch was 99 ppm. The magnesium content increased from 89 to 421 ppm by treatment of the potato starch with an MgCl2 solution. Markedly lower values of peak viscosity and breakdown were observed in calcium- and magnesium-fortified potato starches than in the control potato starch. However, the gelatinization temperature and enthalpy as well as resistant starch content of calcium- and magnesium-fortified potato starches were similar to those of the control potato starch. It is concluded that potato starches with altered pasting properties can be easily manufactured by the use of solutions containing high levels of calcium and magnesium.