Comparative emulsifying properties of octenyl succinic anhydride (OSA)-modified starch: Granular form vs dissolved state

The emulsifying ability of OSA-modified and native starch in the granular form, in the dissolved state and a combination of both was compared. This study aims to understand mixed systems of particles and dissolved starch with respect to what species dominates at droplet interfaces and how stability is affected by addition of one of the species to already formed emulsions. It was possible to create emulsions with OSA-modified starch isolated from Quinoa as sole emulsifier. Similar droplet sizes were obtained with emulsions prepared at 7% (w/w) oil content using OSA-modified starch in the granular form or molecularly dissolved but large differences were observed regarding stability. Pickering emulsions kept their droplet size constant after one month while emulsions formulated with OSA-modified starch dissolved exhibited coalescence. All emulsions stabilized combining OSA-modified starch in granular form and in solution showed larger mean droplet sizes with no significant differences with respect to the order of addition. These emulsions were unstable due to coalescence regarding presence of free oil. Similar results were obtained when emulsions were prepared by combining OSA-modified granules with native starch in solution. The degree of surface coverage of starch granules was much lower in presence of starch in solution which indicates that OSA-starch is more surface active in the dissolved state than in granular form, although it led to unstable systems compared to starch granule stabilized Pickering emulsions, which demonstrated to be extremely stable

Resveratrol loaded Pickering emulsions stabilized by OSA modified rice starch granules

Resveratrol is a photosensitive, bioactive molecule which has received increasing research interest during the past decade for its antioxidant properties. However, it has low solubility in water or common triglyceride oils. Resveratrol solubilization in oil can only be achieved in essential oils, such as flavour oils, but the stability of emulsions produced with this type of oils is low as they are prone to creaming phenomena and Oswald ripening. In this study, resveratrol was first dissolved in orange oil which was mixed into a medium-chain triglyceride (Miglyol) at different ratios and used as the internal phase of oil-in-water emulsions (O/W). The emulsions were stabilized by octenyl succinic anhydride (OSA) modified rice starch granules using two different ratios of starch particle:oil to study the influence of interfacial coverage on the final emulsion droplet size and emulsion stability. The results of this study indicated that stable Pickering emulsions could be prepared using OSA-modified rice starch granules even at partial coverage conditions. Emulsions prepared at an oil fraction of 0.5 using 30% v/v mixture of orange oil in Miglyol as the dispersed phase seemed to be an appropriate resveratrol carrier system, obtaining encapsulation efficiency values close to 90% which results in emulsions with a resveratrol concentration of 8.45 mg/L. Hence, the emulsions prepared are suitable for food fortification applications

Characterization and stability of short-chain fatty acids modified starch Pickering emulsions

Acetylated, propionylated and butyrylated rice and quinoa starches at different levels of modification and starch concentrations, were used to stabilize oil-in-water starch Pickering emulsions at 10% oil fraction. Short-chain fatty acid modified starch Pickering emulsions (SPEs) were characterized after emulsification and after 50 days of storage. The particle size distribution, microstructure, emulsion index, and stability were evaluated. An increase in starch concentration led to a decrease of emulsion droplet sizes. Quinoa starch has shown the capability of stabilizing Pickering emulsions in both the native and modified forms. The emulsifying capacity of SPEs was improved by increasing the chain length of SCFA. Modified quinoa starch with higher chain lengths (i.e. propionylated and butyrylated), at higher levels of modification, showed higher emulsion index (>71%) and stability over the entire 50 days storage. At optimized formulation, SCFA-starch particles have the potential in stabilizing emulsions for functional foods, pharmaceutical formulations, or industrial food applications

Pickering emulsifiers based on hydrophobically modified small granular starches Part II – Effects of modification on emulsifying capacity

Small granular starches from rice, quinoa, and amaranth were modified with octenyl succinic anhydride (OSA) at 5 defined intervals (0–3.0%) and investigated with respect to emulsifying capacity and stability. Starch granule surfaces were characterized by Brunauer–Emmett–Teller and contact angle measurements. Emulsifying capacity was characterized by multiple light scattering (MLS) and particle size analysis. Stability towards environmental stress was characterized by centrifugation and MLS. Surface hydrophobicity and emulsifying capacity correlated with starch type and modification level. Quinoa stabilized emulsions had the smallest droplet size (e.g. 59.2 μm at 3.0% OSA) and superior stability, both before and after centrifugation, especially at the lowest modification levels. Rice and amaranth had larger droplets (99.8 and 84.1 μm at 3.0% OSA respectively). Amaranth, despite its small size showed poorer performance than quinoa, especially at lower modification levels. The higher emulsifying efficiency of quinoa starch granules attributed to the higher protein content

Synthesis of controlled size starch nanoparticles (SNPs)

Starch nanoparticles (SNPs) are a promising choice for the strategic development of new renewable and biodegradable nanomaterials for novel biomedical and pharmaceutical applications when loaded with antibiotics or with anticancer agents as target drug delivery systems. The final properties of the SNPs are strongly influenced by the synthesis method and conditions being a controlled and monodispersed size crucial for these applications. The aim of this work was to synthesize controlled size SNPs through nanoprecipitation and microemulsion methods by modifying main operating parameters regarding the effect of amylose and amylopectin ratio in maize starches. SNPs were characterized by size and shape. SNPs from 59 to 118 nm were obtained by the nanoprecipitation method, registering the higer values when surfactant was added to the aqueous phase. Microemulsion method led to 35−147 nm sizes observing a higher particle formation capacity. The composition of the maize used influenced the final particle size and shape

Combined emulsifying capacity of polysaccharide particles of different size and shape

The aim of this study is to understand mixed systems of two types of particles with different size and shape, quinoa starch granules (NQ) and cellulose nanocrystals (CNC), to stabilize oil-in-water (O/W) emulsions. This study considers the extent of Pickering stabilization with respect to which particle type dominates at droplet interfaces and how stability is affected by the addition of one particle type to already formed emulsions, or combining both, simultaneously. Results demonstrate that the order of addition has an influence allowing to predominantly have NQ particles at the interface when both types are added simultaneously. However when CNC is added first, both types are responsible for emulsion stabilization leading to a system with an intermediate droplet size yet with a higher stability compared to single particle formulations. A dual stabilization mechanism is observed, large particles prevent coalescence and small particles regulate the curvature of the interface and govern the droplet size

Pickering emulsifiers based on hydrophobically modified small granular starches – Part I : Manufacturing and physico-chemical characterization

Small granular starches from rice, quinoa and amaranth were hydrophobized by esterification with octenyl succinic anhydride (OSA) in an aqueous alkaline slurry to obtain series of modified starches at defined intervals (i.e. 0.6, 1.2, 1.8, 2.4, 3.0%). The physical and the physico-chemical properties of the starch particles were characterized by proximate analysis including protein level, amylose level and dry matter. The shape and size of the starch granules were characterized by scanning electron microscopy and light scattering. The gelatinization properties were characterized by differential scanning calorimetry. The degree of modification was determined by titration with NaOH. With regard to the emulsion formulation and in order to assess the emulsifying capacity of the small granular starches, the effect of starch type, degree of modification and starch concentration on the resulting emulsion droplet size were evaluated by light scattering and optical microscopy. Emulsifying properties were found to depend on the degree of substitution, size of the granules and the starch to oil ratio of the formulation. Quinoa starch granules, in general, had the best emulsifying capacity followed by amaranth and rice. However, in higher starch concentrations (>400 mg/mL oil) and adequate levels of OSA (3.0%) amaranth performed best, having the smallest size of starches studied

The effects of pyruvate dehydrogenase kinase 4 (PDK4) inhibition on metabolic flexibility during endurance training in skeletal muscles of streptozotocin-induced diabetic rats

Background: Metabolic flexibility is the capacity of a system to adjust fuel (primarily glucose and fatty acids) oxidation based on nutrient availability. Pyruvate Dehydrogenase Kinase 4 (PDK4) is one of the main enzymes that play a critical role in metabolic flexibility. In current study, we examined PDK4 inhibition along with exercise training (ET) on the gene expression of Estrogen related-receptor alpha (ERRα), medium-chain acyl-CoA dehydrogenase (MCAD), carnitine palmitoyl transferase-16 (CPT-1b), peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α), PDK4 and citrate synthase (CS) in skeletal muscle. Method: Sixty-four male Wistar rats (8 week-old) were randomly divided into 8 groups (n=8); 1- untreated control, 2- STZ-induced diabetic, 3- PDK4 inhibition, 4- endurance training (ET), 5- diabetic+PDK4 inhibition, 6- diabetic+ET, 7- PDK4 inhibition + ET, and 8- diabetic +ET+PDK4 inhibition. ERRα, MCAD, CPT-1b, PGC-1α, PDK4 and CS genes expressions were measured by Real-Time PCR and quantified by 2-��Ct method. Results: ERRα, MCAD, CPT-1b, PGC-1α, PDK4, and CS expressions were significantly higher in non-diabetic+ Endurance Training group compared to the control group. The expressions of CPT-1b, MCAD and CS genes were significantly lower in the non-diabetic+ endurance training/PDK4 inhibition compared to the non-diabetic+ endurance training group, and the expressions of ERRα, CPT-1b and MCAD were significantly lower in the diabetic + PDK4 inhibition group compared to the diabetic group. Conclusion: In sum, PDK4 inhibition has negative effects on lipid metabolism in healthy rats, but in animals with diabetes, PDK4 inhibition can be used for improving lipid metabolism (over-expression of CS and PGC-1α). © 2020, Kerman University of Medical Sciences. All rights reserved

The role of estrogen-related receptor α (ERRα) in metabolic adaptations by endurance training in skeletal muscle of streptozotocin-induced diabetic rats

Aims: The aim of present study was to investigate the effect of endurance training and ERRα inhibition (target for the discovery of new therapies for diseases such as diabetes) on the gene and protein expression of factors involved in lipid metabolism in diabetic rats. Methods: We designed the current study to evaluate the combination of ERRα inhibition and exercise training effects on the expression of ERRα, medium-chain acyl-CoA dehydrogenase (MCAD), carnitine palmitoyltransferase-1b (CPT-1b), pyruvate dehydrogenase kinase 4 (PDK4) and Citrate synthase (CS) in diabetic and non-diabetic rats. Sixty-four male Wistar rats were divided into 8 groups (n = 8) as follows: non-diabetic control, diabetic control (a single dose of 45 mg/kg of STZ), non-diabetic/ERRα inhibition group (received 0.48 mg/kg of XCT790), diabetic/ERRα inhibition group, non-diabetic/exercise training, diabetic/exercise training, non-diabetic rats which received XCT790 and performed exercise training, and diabetic rats which received XCT790 and also performed exercise training. The gene and protein expression were measured by real-time PCR (quantified by 2 -��CT method) and Western blotting method, respectively. Results: Our results showed that the expression of ERRα (1.6-fold), MCAD (4.6-fold), CPT-1b (fivefold), CS (twofold), PDK4 (fourfold), and PGC-1α (fourfold) in the medial gastrocnemius muscle of the non-diabetic exercise training group was significantly higher than the non-diabetic control group. Conclusion: In sum, ERRα is a trainable factor, and its changes are parallel with higher expression of the enzymes which involved in lipid metabolism in healthy rats. ERRα inhibition and endurance training may have positive effects on the lipid metabolism in diabetic rats. This indirectly suggests a significant role of ERRα in the adaptation of lipid metabolism evoked by endurance training. © 2021, Springer-Verlag Italia S.r.l., part of Springer Nature