Rheological and thermal properties of oat flours and starch affected by oat lipids

Structural and functional properties of a high moisture extruded mixture of pea proteins (Pisum sativum), amaranth flour (Amaranthus hypochondriacus), and oat flour (Avena sativa)

Textured vegetable proteins (TVP) are an alternative to meet the increasing demand for non-animal food. This study aimed to develop a TVP from mixtures with 45 % pea protein isolate (PPI) enriched with amaranth (AF) and oat (OF) flours using high-moisture extrusion technology (HME) varying the moisture (50-70 %) and the temperature in the second heating zone of the extruder (110-140 °C). After extrusion, all samples demonstrated higher values of water absorption capacity (WAC) than non-extruded mixtures. Mixture of AF:OF:PPI (40:15:45 %) extruded at 60 % moisture and 135 °C showed promising functional properties with WAC and WSI values of 3.2 ± 0.2 g H2O/g and 24.89 ± 2.31 %, respectively, and oil absorption capacity (OAC) of 1.3 g oil/g. The extrusion process altered the thermal and structural properties of proteins promoting a desirable fibrous structure. This confirms the feasibility of using HME to develop TVP based on PPI, AF, and OF.

Starch-guest complexes interactions: Molecular mechanisms, effects on starch and functionality

Starch is a natural, abundant, renewable and biodegradable plant-based polymer that exhibits a variety of functional properties, including the ability to thicken or gel solutions, form films and coatings, and act as encapsulation and delivery vehicles. In this review, we first describe the structure of starch molecules and discuss the mechanisms of their interactions with guest molecules. Then, the effects of starch-guest complexes on gelatinization, retrogradation, rheology and digestion of starch are discussed. Finally, the potential applications of starch-guest complexes in the food industry are highlighted. Starch-guest complexes are formed due to physical forces, especially hydrophobic interactions between non-polar guest molecules and the hydrophobic interiors of amylose helices, as well as hydrogen bonds between some guest molecules and starch. Gelatinization, retrogradation, rheology and digestion of starch-based materials are influenced by complex formation, which has important implications for the utilization of starch as a functional and nutritional ingredient in food products. Controlling these interactions can be used to create novel starch-based food materials with specific functions, such as texture modifiers, delivery systems, edible coatings and films, fat substitutes and blood glucose modulators.

Rheological, thermal, and in vitro starch digestibility properties of oat starch-lipid complexes

The influence of oat lipids on the structural, thermal, rheological, and in vitro digestibility properties of oat starch under heat processing conditions was investigated. X-ray diffraction, fourier infrared spectroscopy, and differential scanning calorimetry revealed the formation of a V-shaped crystal structure between starch and lipid, resulting in enhanced orderliness and enthalpy. Oat lipids decreased the final viscosity and gel strength of oat starch while weakening the trend towards gel network formation. Additionally, oat lipids exhibited enhanced resistance to starch hydrolase, leading to elevated contents of slowly digestible starch and resistant starch. Consequently, this leads to an augmentation in the rate constants for the rapid digestion fraction (k1) and the slow digestion fraction (k2). When the lipid content reached 7.50 %, a significant increase of 42.20 % was observed in the maximum digestibility of slow digestion fraction (C∞2), while a notable decrease of 44.06 % was noted in the maximum digestibility of rapid digestion fraction (C∞1). The correlation analysis revealed that lipid content, final viscosity, and enthalpy exerted significant influences on in vitro starch digestion. These results demonstrate the substantial impact of lipid content on oat starch structure, subsequently affecting its thermal, rheological, and digestive properties.

Effect of milling and defatting treatment on texture and digestion properties of oat rice

Oat rice with great sensory acceptance was developed based on the combination method of milling and defatting (petroleum ether) treatment. In this study, the effect of milling and defatting treatment on the texture and digestion properties of oat rice was investigated. Results showed that milling and defatting treatment enhanced stickiness, enthalpy, and starch digestibility. The pasting temperature and hardness of oat rice were reduced. The lipid content of oat rice was significantly reduced by milling and defatting treatment, leading to a decrease in the formation of starch-lipid complex. Fourier transform infrared spectroscopy and X-ray diffraction analyses revealed that the application of milling and defatting treatments led to a reduction in the content of starch-lipid complexes in oats during the cooking process. Milling and defatting significantly enhanced both the rapid and slow digestion rates of oat rice. Specifically, the rapid digestion rate was found to be 2.5 times higher than the slow digestion rate. The nutritive components of oat rice were properly preserved, and the viscosity and elasticity of oat rice reached the maximum when milling for 40 s and defatting. This study provides a theoretical basis for oat products.

Preparation of starch-palmitic acid complexes by three different starches: A comparative study using the method of heating treatment and autoclaving treatment

Recent research emphasizes the growing importance of starch-lipid complexes due to their anti-digestibility ability, prompting a need to explore the impact of different starch sources and preparation methods on their properties. In this study, starch-palmitic acid (PA) complexes were prepared by three different starches including Tartary buckwheat starch (TBS), potato starch (PTS), and pea starch (PS) by heating treatment (HT) and autoclaving treatment (AT), respectively, and their physicochemical property and in vitro digestibility were systematically compared. The formation of the starch-PA complex was confirmed through various characterization techniques, including scanning electron microscopy, differential scanning calorimetry, Fourier transform infrared spectroscopy, and X-ray diffraction. Among the complexes, the PTS-PA complex exhibited the highest complexation index over 80 %, while the PS-PA complex had the lowest rapid digestible starch content (56.49-59.42 %). Additionally, the complexes prepared by AT exhibited higher resistant starch content (41.95-32.46 %) than those prepared by HT (31.42-32.49 %), while the complexes prepared by HT held better freeze-thaw stability and hydration ability than those prepared by AT. This study highlights the important role of starch sources in the physicochemical and digestibility properties of starch-lipid complex and the potential application of AT in the preparation of novel resistant starch.

Extrusion as pretreatment for complexation of high-amylose starch with glycerin monostearin: Dependence on the guest molecule

Low-moisture extrusion (LME) can modify starch structures and enrich their functionality. These LME-made starches may efficiently form inclusion complexes (ICs) with hydrophobic guest molecules, which is profoundly impacted by the guest molecule concentration. In this work, the influence of glycerin monostearin (GMS) concentration on the structure and in vitro digestibility of pre-extruded starch-GMS complexes was investigated. The results showed that LME pretreatment increased the complex index of high-amylose starch with GMS by 13 %. The appropriate GMS concentrations produced ICs with high crystallinity and excellent thermostability. The presence of IC retarded amylose retrogradation and dominated bound water in starches. In addition, highly crystallized ICs were resistant to enzymolysis and had a higher proportion of resistant starch. The acquired knowledge would provide a better understanding of the LME-modified starch and GMS concentration-regulated IC formation.

Impact of granule-associated lipid removal on the property changes of octenylsuccinylated small-granule starches

Starch granule associated lipids (GALs) are known to alter the properties and functions of small granule starches. To test the hypothesis that the removal GALs from small granule starches could increase the overall reactive surface and improve octenyl-succinylation (OSA) modification efficiency, four small granules starches from rice, oat, quinoa, amaranth and a waxy maize starch were subjected to defat, OSA esterification and combined defatted and OSA treatment. The combined treatment showed a significant improvement in the degree of substitution for all starches from both tritration and 1H NMR methodologies. Confocal microscopy revealed a more uniform distribution of OSA groups on the starch surface. After GALs removal, the bimodal granule size distribution was diminished but reappeared during OSA modification. Pasting viscosity increased for the OSA and GALs removed quinoa, waxy maize and amaranth starches, but it decreased on modified rice and oat starches. OSA treatment alone significantly altered the gelling and rheological properties towards a more soft and less stable starch structure. The combined treatment compensated these changes to some extent and filled the property gap between the native and OSA modified starches. This study demonstrated that removing GALs can achieve more profound OSA derivatization.

Effects of milling on texture and in vitro starch digestibility of oat rice

Compared with other oat products, consumers in China prefer oat rice and porridge made from naked oat. However, this oat product usually has poor sensory acceptance, which is directly related to the texture properties. This study aimed to use the milling method to improve the oat rice texture. The nutrient component, microstructure, pasting, and thermal properties of oat treated with different degrees of milling (0 s, 20 s, 40 s, 60 s, and 80 s) were researched. The results showed that milling would damage the bran layer of oat rice, increasing starch, β-glucan, total leached solids content, and the gelatinization enthalpy (ΔH). Meanwhile, oil, protein content, the pasting viscosity, and the pasting temperature were decreased. Milling made oat rice sticky and soft, and the bound water and non-flowing water migrated like flowing water. The cross-section of oat rice showed that milling damaged the surface of oat rice, which was beneficial to water entry and starch dissolution, and increased the viscosity of oat rice. When the milling time was 40 s and 60 s, the appearance, aroma, taste, texture, and overall acceptability of oat porridge were better. Moreover, rapid digestion fraction (k1) and slow digestion fraction (k2) are the lowest and have the effect of low blood glucose rise rate.

Techno-Functional and Rheological Properties of Alternative Plant-Based Flours

The use of alternative vegetal sources is a proposed strategy to improve the diversity and quality of plant-based products on the market, currently led by soy and pea. This study compares the techno-functional properties of seven vegetable flours (chickpea, lentil, red lentil, white bean, quinoa, amaranth, and oat) and the rheological properties of their flour pastes and gels. All techno-functional properties significantly (α = 0.05) varied depending on the type of flour. Among the flours studied, the highest swelling capacity was for white bean and the lowest for chickpea and red lentil. Water holding capacity was high for white bean and oat flours and low for red lentil. Oat and quinoa flours had the highest oil-holding capacity. Emulsifying and foaming capacities were high for all pulse flours but poor for amaranth and oat flours. However, amaranth and oat provided a much higher viscosity during heating than the rest of the flours. The viscoelastic properties of the flour pastes indicated that they all had a gel structure with storage modulus (G′) values over loss modulus (G″) values. From the viscoelastic properties, amaranth and quinoa showed a weak gel structure with low G′ and G″ values, and the chickpea, lentil, and red lentil formed pastes with a high elastic contribution (high G′ values). In agreement, these three pulse flours were the only ones able to form hard, self-standing gels. These results show the potential of vegetal flours from alternative sources in the development of new plant-based products.

Effects of high temperature, high humidity, and cold storage on structure and qualities of whole oat flour noodles during processing

Gelation and structure of oat starch significantly affect qualities of whole oat flour noodles. During extrusion, the structure of noodles is loose, resulting in high cooking loss and poor texture. Therefore, oat noodles were treated with high temperature, high humidity (HTH), and cold storage (CS), and their structure and qualities were analyzed. The results showed that compared with CS, HTH could reduce the cooking loss of noodles from 10.12% to 6.13%, increase the hardness (65.59 g) and chewiness (20.67) of noodles, and effectively improve the sensory quality of noodles. The change in texture and sensory of noodles was due to HTH by accelerating the retrogradation of starch in noodles, promoting the cross-linking of starch molecules to form an ordered structure, causing an increase in the ordered degree and crystallinity of starch and making the structure of noodles denser. It made the mobility of water in the noodles decrease, and more tightly bound water was transformed into weakly bound water and free water. HTH can be applied to industrial production of whole oat flour noodles. This study could effectively guide the production of high-quality whole oat flour noodles without any food additives.

Pasting, Rheological, and Tribological Properties of Rice Starch and Oat Flour Mixtures at Different Proportions

Rice starch (RS) and oat flour (OF) were mixed in different proportions, and the pasting properties, particle size, rheology, and tribological properties of the mixed system were analyzed. According to the RVA results, OF inhibited the starch pasting, and the pasting temperature and peak viscosity of the mixed system increased. The particle size shifted toward the small particle size after the mixing of RS and OF components, and the RS/OF 9/1 particle size is the smallest. All samples exhibited shear dilution behavior and the viscosity of the system could be significantly increased at a 10 wt% RS content. At sliding speeds of >1 mm/s, the friction of the mixture is usually between the two individual components, which also confirmed the association or interaction between the two polymers.

Effect of Hydrothermal Cooking and Germination Treatment on Functional and Physicochemical Properties of Parkia timoriana Bean Flours: An Underexplored Legume Species of Parkia Genera

The present study was undertaken to analyze the impact of germination (NBG) and hydrothermal cooking (NBHTC) on the nutritional profile and physicochemical, functional and microstructural properties of Nitta bean (Parkia timoriana) (NBR) seeds. Results demonstrated that the highest crude protein and fat content could be found in NBG and NBHTC, whereas the ash content was significantly higher in NBG. Compared to NBHTC and NBR, NBG has higher emulsion capacity and stability, with values determined to be 58.33 ± 1.67 and 63.89 ± 2.67, respectively. In addition, the highest color intensity was also reported for NBG, followed by NBHTC and NBR. Likewise, NBG showed complete gel formation at a lower concentration (12 g/100 mL) than NBR flour (18 g/100 mL). Furthermore, structural changes in the lipid, protein, and carbohydrate molecules of NBG and NBHTC were evidenced by FTIR studies. Morphological changes were noticed in different samples during microscopic observations subjected to germination and hydrothermal treatment. In contrast to NBR and NBHTC, NBG showed the highest total polyphenol content, ORAC antioxidant, and DPPH radical scavenging activity, which demonstrated the potential utilization of Nitta bean flour as a natural plant-based protein source in food security product formulations.

Improving the cold water swelling properties of oat starch by subcritical ethanol-water treatment

The granular cold water swelling oat starch was prepared by subcritical ethanol-water, and the changes of properties and structure on oat starch were investigated. The oat starch was modified at the temperature of 95 °C and ethanol concentration of 48% and showed a higher cold water swelling ability of 22.58 g/g, whereas native oat starch was 6.73 g/g. Modified oat starch granule was kept intact, and it was swollen when dispersing in the water. The gelatinization enthalpy declined to 0 J/g. The surface of modified oat starch granules was honeycomb and porous observed by scanning electron microscope. The X-ray diffraction showed the A-type crystal decreased and the V-type crystal increased, and the result was quantitatively confirmed by solid-state ¹³C NMR spectroscopy. The ratio of 1047 cm^-1/1022 cm^-1 (determined by Fourier transform infrared spectroscopy) of modified oat starch was decreased. The molecular weight distribution of modified oat starch was slightly reduced, and the amylose content increased from 26.18% to 31.68%, and only a small amount of carbohydrates leached during the modification. Subcritical ethanol-water modification improved the cold water swelling ability of oat starch. The starch crystals changed from A-type to V-type provide a potential mechanism of subcritical ethanol-water modified oat starch.