Impact of the degree of octenyl succinylation on metal ions complexation and functional properties of maize starch.

A study was carried out to determine the physicochemical and emulsifying properties of pre-treated octenyl succinic anhydride (OSA) sago starch in simple emulsion. Sago starch was pre-treated with STARGEN enzyme (EN OSA: single pre-treatment), heat moisture treatment followed by STARGEN enzyme (HMT EN OSA: dual pre-treatment) before being esterified with OSA. The ability of the pre-treated OSA sago starch to stabilize emulsion was then investigated. Dual pre-treated starch, HMT EN OSA, had significantly highest degree of substitution (DS), (DS = 0.0179) compared to single pre-treated starch, EN OSA, (DS = 0.0159) and native OSA, N-OSA (DS = 0.0057). As compared to emulsions prepared by N-OSA and HMT EN OSA, EN OSA had significantly highest emulsifying activity throughout all starch concentrations and it produced a thick viscous emulsion layer directly after emulsification. This might be due to enzymatic pretreatments may retained granule’s original shape and smooth appearance which allow having a better fit during the emulsification process. The highest emulsion stability was observed with the emulsion index values of EN OSA stabilized emulsions was the most stable for all starch concentrations throughout storage study. After the 8th week of storage study, the EN OSA remains the highest emulsion index from 0.37 to 0.56 for 200 mg/mL oil to 500 mg/mL oil starch concentration. Light micrograph of EN OSA showed that starch particles accumulated at the oil-water interface and cover the oil droplets with higher degree of coverage than the HMT EN OSA and control. No spaces were observed in the EN OSA stabilized emulsion which indicated that EN OSA modified sago starch can effectively stabilize oil in water emulsion.

Octenyl succinic anhydride (OSA) starch is widely used to stabilize emulsions. Nevertheless, the poor compatibility of starch with hydrophobic groups has restricted the performance of OSA modification. In this work, potato starch was pre-treated once or twice (dry heating, acetylation, and acid modification) prior to OSA modification. Pre-treatments increased the degree of substitution (DS), hydrophobicity, hydrophilicity, and decreased amylose content of OSA starches, with dual pre-treatments having greater effects. Among all pre-treatments, acid modification followed by dry heating resulted in the greatest OSA modification (DS: 0.015) and water-binding capacity (155%). Meanwhile, acid modification followed by acetylation produced OSA starch with the highest oil-binding capacity (290%). Scanning electron microscopy revealed that the granular deformation of dual pre-treated OSA starches was greater compared to single pre-treated and non-pre-treated OSA starches (O). Dual pre-treated OSA starches (ADO, 7%; ACO, 8%) had lower amylose contents than those of single pre-treated (AO: 12%, CO: 17%, DO: 21%) and O (36%). All the pre-treatments reduced the setback viscosity of OSA starch to a lower range (70–394 cP), simultaneously decreasing their retrograde tendency. This study suggested that dual pre-treatments could improve the efficiency of OSA modification and produce OSA starch with greater emulsifying potential.

Effect of metal ions on physicochemical and rheological properties of octenyl succinate starches

Chemical composition, digestibility and emulsification properties of octenyl succinic esters of various starches

SummaryThe objective of this study was to determine the effect of complexation of oxidised starch with mineral elements on its physicochemical properties. Corn starch was oxidised with sodium hypochlorite and, afterwards, modified with ions of potassium, magnesium and iron. Thus, native and modified starches were analysed for: contents of mineral elements, colour parameters (L*a*b*), water binding capacity and solubility in water at temperature of 60 and 80 °C. Thermodynamic characteristics of gelatinisation by DSC, molecular weight distribution by GPC, intrinsic viscosity and pasting properties by RVA were studied. The efficiency of incorporation of metal ions into oxidised corn starch was about 30%, 20% and 20% for potassium, magnesium and iron ions, respectively. The complexation with potassium ions caused the greatest changes in the molecular weight distribution and the intrinsic viscosity of starches and viscosity of starch pastes. Only modification of starch with iron ions affected the colour parameters of the starch. Incorporation of metal ions into starch resulted also in changes in its water binding capacity and solubility in water.

This study investigated the effects of octenyl succinate (OS) starches mixed with oleic acid on functional properties and potential use in edible films. Potato starches esterified with 1%, 3%, 5%, or 7% of octenyl succinic anhydride (OSA) were mixed with oleic acid. Degree of substitution (DS), hydrodynamic volume, and lipid content were measured to evaluate effectiveness of modification. Blank sample and modified starches were analyzed for water binding capacity, solubility, characteristic of gelatinization, pasting properties, and surface/interfacial tensions. Edible films were prepared from the obtained starches and tested for water vapor permeability, water binding capacity, and solubility. The complexation index increased linearly with DS. Oleic acid reduced water binding capacity and solubility, particularly at 80 °C, altered thermodynamic characteristic of gelatinization, decreased viscosities of OS starch pastes, and increased pasting temperatures by up to 20%. It also enhanced the surface tension lowering effect of OS starch and reduced water vapor permeability in films, especially at higher DS. Films from starch–oleic acid mixtures exhibited lower water binding capacity and solubility, notably in 5% and 7% OSA modified starch. Results show that oleic acid addition to OS starch markedly affect functional properties of starch, highlighting its potential for use in edible film applications.

This thesis is the first comprehensive study into the relationship between starch structure and the functional properties of its derivatives made by modification with octenylsuccinic anhydride (OSA). Several new methods have been developed in the process of this work, using a range of purposefully created octenylsuccinylated (OS) starches with controlled structures. Chapter 1 is a general introduction to the science involved and the state of the art. Chapters 2 to 4 explore methods in the development of structurally targeted OS starches. Chapters 3, 5 and 6 report the results from some analyses. As outlined in Chapter 1, OS starches represent an economically important product that has existed for many decades, but has recently shown significant growth in interest as seen in scientific literature. The reasons for this impressive surge in interest reflects the wide range of applications and versatility OS starches, determined primarily from the structural properties of the starch substrate. With that in mind, it is surprising that, to date, most interest has been focussed on conditions of the OSA modification process, rather than the structure-function relationships. After a comprehensive state-of-the-art review, this thesis has identified the important areas where structure-function research of OS starches should focus in-depth to provide the most thorough innovation in the field. Throughout, size exclusion chromatography (SEC) and nuclear magnetic resonance (NMR) have been used for structural analysis, while gel properties and emulsion function have been determined using a wide range of methods. Chapter 2 outlines NMR methods that were developed specifically for this project. It has been determined that the ideal system for analysing OS starches by NMR utilises 64 to 128 scans in deuterated dimethylsulfoxide (DMSO-d6) of at least 50 °C containing at least 22 mg mL-1 deuterated trifluoroacetic acid (TFA-d1), as has been published and improved upon during the course of this thesis. The method utilises the signal from the proton attached to the 5th Carbon residue of the octenyl tail to determine the number of OS groups, and compares that to the total number of monomers by the addition of α-(1→4), α-(1→6) and reducing end signals. The signal of the 5th proton is unique, because it neighbours the double bond. Due to the susceptibility of the double bond to the effects of TFA-d1, the analysis must be performed very quickly for best results. By this method it is possible to determine the degree of branching (DB) and the degree of OS substitution (DS) using the one simple analysis. Because it also accurately measures DB, the same method has proven useful for non-OSA-modified starches. Chapter 3 is an overview of the development and initial application of a method to determine the critical aggregation concentration (CAC, sometimes called “critical micelle concentration”, though the aggregates formed by OS starches are not by definition micelles). The method uses pyrene fluorescence and can be adapted for other polymeric surfactants, and has been used in this first instance to investigate a range of acid-hydrolysed starches. These starches were prepared by reaction with HCl in various alcoholic solvents. Acid hydrolysis has been found to be ideal for creating starch substrates of tailored hydrodynamic volume (Vh), with fairly low dispersity. The values determined by CAC analysis reflect the capacity of the surfactant to interact with itself and with interfaces, and are a useful and simple method of comparing surfactants; however, the results do not always translate directly into emulsion stability or overall quality. As outlined, OS starches from highly branched substrates show similar CAC characteristics to those seen with more linear synthetic polymer surfactants. Chapter 4 deals with the β-amylolysis of OS starch, particularly the effect of OS groups on the β-amylase activity. To achieve this, starches from waxy sorghum and waxy maize were modified with OSA to a range of DS, including very high levels beyond those used in industry. Hydrolysis by β-amylase was performed on both granular and gelatinised starches. Because the OSA modification process is on starch in granular form the reaction is heterogeneous with those areas accessible to the solvents more readily accessible; similarly, β-amylolysis in granular form restricted access of the enzyme to many of the same areas of the granule in which the esterification had predominantly occurred, whereas in gelatinised form the β-amylase activity was much more unhindered. The activity of the enzyme was somewhat diminished by the presence of OS groups, though the results were not so conclusive as to indicate complete blocking of the enzyme activity along individual branches. Chapter 5 introduces the critical test of emulsion capacity and stability, as well as an important method for determining the breakdown of β-carotene in the oil phase of emulsions. The method is an accelerated test at high storage temperature that can determine the oxidative effects on any labile components in the oil phase. The methods of acid hydrolysis used in Chapter 5 are similar to those in Chapter 3; however, the spectrum of samples is more broad and encompasses a range of structural variables. Amylose/amylopectin ratio is used as a simple method of controlling the DB, and the molecules are reduced to controlled sizes through the use of acid hydrolysis in alcohols. Methods for determining the quality of starch surfactants in the formulation and stabilisation of emulsions use high-pressure homogenisation (HPH) and track the development of pigment and droplet size during incubation at 55 °C over 20 days. The results of these tests indicate that samples containing many short branches from amylopectin are more stable than those containing longer amylose chains, regardless of the overall degree of branching (DB) of the surfactant. The effects of shear scission during HPH are also elucidated in this chapter to a greater extent than has previously been demonstrated with OS starches. Chapter 6 brings together the methods from all previous chapters to determine the CAC, emulsion capacity and stability and oxidative stability of β-carotene dissolved in the oil phase of several waxy maize and sorghum starches, after they were modified with OSA, structurally modified with β-amylase or pullulanase, and characterised using SEC and NMR. The size of oil droplets in emulsion can be higher in samples of larger Vh without any sacrifice to emulsion stability, probably due to the layer thickness at the interface. Larger molecules of amylopectin also result in better chemical stability of β-carotene and lower CAC; however, attempts to artificially increase DB by treatment with β-amylase have a detrimental effect to emulsion stability, while lowering the degree of branching with pullulanase does not show the inverse effect. As a result of this thesis, several advances have been made in the field of OS starch science. The common empirically based tendency of industrially prepared OS starches to be based on waxy starches and prepared by HPH has been validated by the findings that hydrodynamic size and short branch length contribute to the quality of emulsion formulations. Treatment of industrial starches with β-amylase does not lead to useful surfactant properties, and from the results of this study such methods can be excluded from future consideration. This thesis is the first document in the field to indicate that higher DB does not directly lead to better emulsions, rather than the presence of short linear branches in a mix also containing larger, branched molecules. Waxy sorghum has been established as a viable source of OS starch substrate, opening up opportunities for future research and industrial production in the Australian market.

Effect of octenylsuccinylation on physicochemical, thermal, morphological and stability of octenyl succinic anhydride (OSA) modified sago starch

Properties of octenyl succinic anhydride (OSA) modified starches and their application in low fat mayonnaise.

Octenyl succinylation of kefiran: Preparation, characterization and functional properties

Development of emulsifying property in Persian gum using octenyl succinic anhydride (OSA)

Preparation and properties of octenyl succinic anhydride modified potato starch

Octenyl succinic anhydride (OSA) modified starch from waxy rice was prepared using dry media milling. The characteristics of OSA were investigated by laser particle analyzer, FT‐IR spectroscopy, XRD, and DSC. Degree of substitution (DS) and reaction efficiency (RE) were significantly (p<0.05) influenced by sodium hydroxide concentration, OSA concentration, and mechanical activation time. The suitable processing conditions for preparing octenyl succinic anhydride starch (OSA starch) were determined to be 0.9 g sodium hydroxide per 100 g starch, 4 g OSA per 100 g starch, and 20 h of mechanical activation. Intensities of characteristic peaks at 1724 and 1572 cm−1 in FT‐IR spectrogram increased with DS, which confirmed the successful introduction of ester carbonyl groups into the starch. Size distribution analysis and XRD indicated that the increased DS and RE by dry media milling were attributed to both the decrease of starch granule size and the destruction of the crystalline structure. DSC results showed that the gelatinization temperature of the OSA starch decreased with the increase of DS.

Structure and physicochemical properties of octenyl succinic esters of sugary maize soluble starch and waxy maize starch

Fat replacers have been developed to produce low‐calorie foods due to the association of fat‐rich diet to lifestyle diseases. Teff (an underutilized and under‐researched cereal), and maize starch pastes modified with stearic acid could be used as fat replacers because of their reduced gelling ability and higher viscosity. The effects of teff and maize starch pastes modified with stearic acid on the rheological properties, microstructure, freeze–thaw, and high temperature stability of low‐calorie mayonnaise type emulsions (LCMTE) were investigated. Starch suspensions (10% w/v) containing stearic acid (1.5%) were pasted and used to prepare LCMTE with 50 and 80% oil replacement. LCMTE with modified teff and maize starches had lower yield stress and viscosity and larger oil droplets compared to LCMTE with unmodified teff and maize starches. Increasing oil replacement level (50–80%) increased the viscosity. LCMTE with maize starch had higher yield stress and viscosity and smaller oil droplets than LCMTE with teff starch. All samples showed shear thinning behavior (n < 1). All the LCMTE were more stable to freeze–thaw cycles and high temperature storage than full fat mayonnaise. At 50% oil replacement, unmodified and modified teff and maize starch with stearic acid could produce LCMTE. When the oil content replacement was further increased to 80% only the LCMTE with modified starches were similar to the full fat. The LCMTE made with unmodified teff and maize starches (especially those with 80% oil replacement) did not flow like a mayonnaise compared to LCMTE made with stearic acid modified starches.