Effects of dextran with different molecular weights on the quality of wheat sourdough breads

Revealing the mechanism underlying the viscosity improvement of rice protein yogurt by the presence of in-situ-produced dextrans

The in-situ-produced dextrans (DXs) could effectively enhance the viscosity of rice protein (RP) yogurt, but the reason for this improvement has not been elucidated. This study aims to reveal the mechanism underlying the viscosity improvement of RP yogurt by the presence of in-situ DXs. DXs synthesized in RP yogurts under different optimum conditions were purified and fully characterized. RP yogurts were simulated by mixing RP, DXs, lactic acid, and acetic acid according to their real concentrations. The impacts of DXs on the physicochemical properties of RP and the molecular dynamics of the polymers were examined. The minor difference in branching degree (from 5.79 % to 7.08 %) and conformation of DXs could not result in a significant difference in their macromolecular and thermal properties. DXs interacted with RP through hydrogen bonds, leading to a refolding of RP and the formation of a "core-shell" structure. The immobilized water molecules in the networks of DXs and RP-DX mixtures, the friction force among the DX molecules, and the hydrogen bonds formed between DXs and RP were responsible for the viscosity improvement of RP yogurts containing in-situ DXs. This study may guide the application of DXs in plant-protein food and prompt the exploitation of plant-protein resources.

Insights into the starch and proteins molecular structure changes of foxtail millet sourdough: Effect of fermentation from grains of cereal to pre-meal

This study investigated the effects of foxtail millet sourdough fermentation time (0, 8, 16, and 24 h) on the protein structural properties, thermomechanical, fermentation, dynamic rheological, starch granules crystalline regions molecular mobility, and starch microstructural characteristics. The fermentation led to a significant increase in the concentration of free amino acids from protein hydrolysis. Fourier transform infrared spectroscopy (FTIR) revealed changes in protein secondary structure and the presence of functional groups of different bioactive compounds. The result of thermomechanical properties showed a significant increase in the stability (0.70-0.79 min) and anti-retrogradation ability (2.29-3.14 Nm) of lactic acid bacteria (LAB) sourdough compared to the control dough, showing a wider processing applicability with radar profiler index. In contrast, sourdoughs with lower tan δ values had higher elasticity and strength. Scanning electron microscopy showed that the surface of the starch appeared from smooth to uneven with patchy shapes and cavities, which declined the crystallinity from 34.00 % to 21.57 %, 23.64 %, 25.09 %, and 26.34 % respectively. Fermentation changed the To, Tp, Tc, and ΔH of the starch. The results of the study will have great potential for application in the whole grain sourdough industry.

Effects of dextran molecular weight on starch retrogradation and technological properties of Chinese steamed bread: Based on the rubber/glass transition

From the perspective of rubber/glass transition, this study clarified that the impact of dextran on retarding hardening behavior and slowing starch retrogradation of Chinese Steamed Bread (CSB) depended on its molecular weight and concentration level. Guggenheim-Anderson-de Boer (GAB) model was fitted to explore critical behavior changes in rubber/glass transition of CSB. Incorporation of high molecular weight dextran enhanced the elasticity of dough and porosity of CSB, reduced the aging and hardening degree of CSB at appropriate addition levels. CSB hardness showed a growing tendency during storage, while macromolecular dextran reduced the hardness and retrogradation degree by 22.87 % and 67.53 %. Dextran with high molecular weights lowered the glass transition temperature (Tg) and improved the moisture sorption and molecular mobility of CSB under various relative humidity (RHs) conditions by providing hydrophilic sites or intermolecular space to bind water molecules. Meanwhile, it reinforced the binding between denatured gluten and gelatinized starch. Both of them devoted to starch retrogradation inhibition and stable quality maintenance of CSB. CSB is suggested to maintain stable quality at room temperature with RHs ≤33 % to prevent rubber/glass transition. This work provided theoretical guidance for fractionation application of dextran to regulate the quality and extend the shelf-life of flour products.

Improvement on wheat bread quality by in situ produced dextran-A comprehensive review from the viewpoint of starch and gluten

Deterioration of bread quality, characterized by the staling of bread crumb, the softening of bread crust and the loss of aroma, has caused a huge food waste and economic loss, which is a bottleneck restriction to the development of the breadmaking industry. Various bread improvers have been widely used to alleviate the issue. However, it is noteworthy that the sourdough technology has emerged as a pivotal factor in this regard. In sourdough, the metabolic breakdown of carbohydrates, proteins, and lipids leads to the production of exopolysaccharides, organic acids, aroma compounds, or prebiotics, which contributes to the preeminent ability of sourdough to enhance bread attributes. Moreover, sourdough exhibits a "green-label" feature, which satisfies the consumers' increasing demand for additive-free food products. In the past two decades, there has been a significant focus on sourdough with in situ produced dextran due to its exceptional performance. In this review, the behaviors of bread crucial compositions (i.e., starch and gluten) during dough mixing, proofing, baking and bread storing, as well as alterations induced by the acidic environment and the presence of dextran are systemically summarized. From the viewpoint of starch and gluten, results obtained confirm the synergistic amelioration on bread quality by the coadministration of acidity and dextran, and also highlight the central role of acidification. This review contributes to establishing a theoretical foundation for more effectively enhancing the quality of wheat breads through the application of in situ produced dextran.

In-depth understanding of the effects of different molecular weight pullulan interacting with protein and starch on dough structure and application properties

This work clarified the positive effects of pullulan on dough structure and application properties varied with its molecular weight. Pullulan with different molecular weights were introduced into dough system to explore their intervention effects on structural and technological properties of dough as well as physical and digestion properties of biscuits. Results showed that HPL (pullulan with molecule weight of 100- 300 kDa) could increase the intermolecular collisions, prompt the protein aggregation and limit the water migration in dough system, resulting in an integrate, continuous and dense network structure of the gel with strengthened elasticity and weakened extensibility, which caused an increase in biscuit thickness, hardness and crispness. On the contrary, LPL (pullulan with molecule weight of 3- 100 kDa) could go against the formation of stable and elastic dough through breaking down cross-linkage between protein and starch so as to provide biscuits with decreased hardness and crispness during baking. Both HPL and LPL delayed starch pasting and retrogradation process while HPL had the stronger retarding effect on starch digestibility of biscuits than LPL. These findings dedicated to a better understanding of pullulan function in dough system and provide suggestions for fractionation applications of pullulan in food field.

Effect of vanillin-conjugated chitosan-stabilized emulsions on dough and bread characteristics

In this study, the effect of chitosan-vanillin Schiff base emulsions (CSVAEs) on dough and bread characteristics was investigated. The results revealed that CSVAEs were embedded in the gluten and that the viscoelasticity and mechanical strength of the dough gradually increased with increasing CSVAEs concentration, α-helical and β-fold content, and elastic structure in the dough increased with the same patterns. The basic properties of bread were measured, and it was found that low concentrations of CSVAEs were effective in improving the quality of bread and slowing the staling rate. As the storage time increased, CSVAEs had less effect on the rate of moisture loss, hardness and springiness of the bread and more effect on the inhibition of the acidity of the bread. The addition of CSVAEs slowed the increase in bacteria and molds and extended the shelf life of the bread.

Regulation of baking quality and starch digestibility in whole wheat bread based on β-glucans and protein addition strategy: Significance of protein-starch-water interaction in dough

Whole wheat bread has high nutritional value but is characterized by inferior quality and a high glycemic index. Studies have shown that adding β-glucans and protein can improve bread quality. This study investigated the effects of added oat β-glucan, barley β-glucan, or yeast β-glucan on protein synergy and whole wheat dough and bread quality. The mixing properties, rheological properties, and scanning electron microscopy observations showed that the addition of β-glucan promoted the formation of gluten networks, while the synergy between the wheat proteins and β-glucan resulted in a more robust and stable gluten network and a stronger physical starch envelope. Rapid visco-analysis and thermal property evaluations showed that β-glucan addition inhibited the thermal degradation, gelatinization, and retrogradation of starch. Based on the bread quality results, it was found the β-glucan could cause some damage to the bread baking quality. For example, the hardness of samples with oats, barley, and yeast increased to 881.69 g, 952.97 g, and 631.75 g, respectively, compared to samples without β-glucan (317.49 g), whereas the inclusion of yeast β-glucan proved to be less detrimental. Protein and β-glucan both reduced starch digestion to some degree, and showed better synergistic effects, with the lowest estimated glycemic index of 70.08 observed in bread containing added yeast β-glucan and protein. Therefore, yeast β-glucan and protein mixtures could be selected as viable formulations for enhancing the quality of whole wheat bread.

Impact of exopolysaccharides-producing lactic acid bacteria on the chemical, rheological properties of buckwheat sourdough and the quality of buckwheat bread

Exopolysaccharides (EPS) produced in situ by lactic acid bacteria (LAB) during sourdough fermentation have the potential to replace hydrocolloids in gluten-free sourdoughs. This study investigated effects of an EPS-producing Weissella cibaria NC516.11 fermentation on chemical, rheological properties of sourdough and the quality of buckwheat bread. Results indicate that the buckwheat sourdough fermentation by W. cibaria NC516.11 had lower pH (4.47) and higher total titrable acidity (8.36 mL) compared with other groups, and the polysaccharide content reached 3.10 ± 0.16 g/kg. W. cibaria NC516.11 can significantly improve the rheological properties and viscoelastic properties of sourdough. Compared with control group, the baking loss of NC516.11 group bread decreased by 19.94%, specific volume increased by 26.03%, and showed good appearance and cross-sectional morphology. Scanning electron micrograph revealed an intact and less porous cell structure. Meanwhile, W. cibaria NC516.11 significantly improved the texture of the bread and reduced the hardness and moisture loss during storage.

Biopolymers Produced by Lactic Acid Bacteria: Characterization and Food Application

Plants, animals, bacteria, and food waste are subjects of intensive research, as they are biological sources for the production of biopolymers. The topic links to global challenges related to the extended life cycle of products, and circular economy objectives. A severe and well-known threat to the environment, the non-biodegradability of plastics obliges different stakeholders to find legislative and technical solutions for producing valuable polymers which are biodegradable and also exhibit better characteristics for packaging products. Microorganisms are recognized nowadays as exciting sources for the production of biopolymers with applications in the food industry, package production, and several other fields. Ubiquitous organisms, lactic acid bacteria (LAB) are well studied for the production of exopolysaccharides (EPS), but much less as producers of polylactic acid (PLA) and polyhydroxyalkanoates (PHAs). Based on their good biodegradability feature, as well as the possibility to be obtained from cheap biomass, PLA and PHAs polymers currently receive increased attention from both research and industry. The present review aims to provide an overview of LAB strains' characteristics that render them candidates for the biosynthesis of EPS, PLA, and PHAs, respectively. Further, the biopolymers' features are described in correlation with their application in different food industry fields and for food packaging. Having in view that the production costs of the polymers constitute their major drawback, alternative solutions of biosynthesis in economic terms are discussed.

Rheo-Fermentation Dough Properties, Bread-Making Quality and Aroma Characteristics of Red Bean (Vigna angularis) Sourdough Induced by LAB Weissella confusa QS813 Strain Fermentation

This study investigated the impact of in situ-formed exopolysaccharides (EPS) in red bean (Vigna angularis) sourdough fermented by Weissella confusa QS813 on dough rheo-fermentation properties, bread-making quality and aroma characteristics of red bean sourdough bread. The EPS formed in red bean sourdough and sourdough-induced acidification improved the maximum dough fermentation height, gas retention coefficient and viscoelastic properties of dough. Doughs had a lower increase rate of total SDS-soluble gluten proteins, a low decline in GMP content and similar free sulfhydryl content to wheat dough. Resultantly, breads showed declines in baking loss and hardness, increase in specific volume and lower moisture loss and staling rate after 7 days of storage. Finally, despite a reduction in the total content of aroma compounds, new aroma compounds such as acetic acid and higher contents of 3-methyl-1-butanol and 2,3-butanediol were enriched in red bean sourdough bread. Sourdough acidification probably promoted interaction of EPS with gluten or red bean proteins through bond interactions to form structures which stabilized gluten in dough and increased water-binding ability in red bean sourdough bread. This study provided a better understanding of the role of EPS in sourdough in improving bread quality and of promising strategies to address consumer demand for nutritious and clean-label products.

Weissella cibaria riboflavin-overproducing and dextran-producing strains useful for the development of functional bread

This work describes a method for deriving riboflavin overproducing strains of Weissella cibaria by exposing three strains (BAL3C-5, BAL3C-7, and BAL3C-22) isolated from dough to increasing concentrations of roseoflavin. By this procedure, we selected one mutant overproducing strain from each parental strain (BAL3C-5 B2, BAL3C-7 B2, and BAL3C-22 B2, respectively). Quantification of dextran and riboflavin produced by the parental and mutant strains in a defined medium lacking riboflavin and polysaccharides confirmed that riboflavin was only overproduced by the mutant strains, whereas dextran production was similar in both mutant and parental strains. The molecular basis of the riboflavin overproduction by the mutants was determined by nucleotide sequencing of their rib operons, which encode the enzymes of the riboflavin biosynthetic pathway. We detected a unique mutation in each of the overproducing strains. These mutations, which map in the sensor domain (aptamer) of a regulatory element (the so-called FMN riboswitch) present in the 5' untranslated region of the rib operon mRNA, appear to be responsible for the riboflavin-overproducing phenotype of the BAL3C-5 B2, BAL3C-7 B2, and BAL3C-22 B2 mutant strains. Furthermore, the molecular basis of dextran production by the six W. cibaria strains has been characterized by (i) the sequencing of their dsr genes encoding dextransucrases, which synthesize dextran using sucrose as substrate, and (ii) the detection of active Dsr proteins by zymograms. Finally, the parental and mutant strains were analyzed for in situ production of riboflavin and dextran during experimental bread making. The results indicate that the mutant strains were able to produce experimental wheat breads biofortified with both riboflavin and dextran and, therefore, may be useful for the manufacture of functional commercial breads.

Structural characterization of exopolysaccharides from Weissella cibaria NC516.11 in distiller grains and its improvement in gluten-free dough

In this study, an exopolysaccharide (EPS) was produced by Weissella cibaria NC516.11 isolated from distiller grains of Chinese Baijiu. The structural characterization of EPS determined using fourier transform infrared spectra and nuclear magnetic resonance spectra demonstrated that W. cibaria NC516.11 had α-(1 → 6) (93.46%) d-glucose linkages with a few α-(1 → 3) (6.54%) d-glucose linked branches. The monosaccharide composition of the EPS was glucose, and its molecular weight was 2.82 × 10⁶ Da. Scanning electron microscopy showed that the microstructure of EPS had a three-dimensional structure at low magnification and a particle structure that protruded from the surface at high magnification. The addition of EPS into dough can promote the cross-linking of starch molecules and increase the water-holding capacity. Dynamic rheology indicated that the aqueous solution of EPS is a pseudoplastic fluid, and the higher the concentration of EPS, the greater the viscosity. The addition of EPS to the gluten-free dough showed G' > G", which could increase the viscoelastic properties of the dough and enhance the gluten network.

Extraction, purification and characterisation of exopolysaccharides produced by newly isolated lactic acid bacteria strains and the examination of their influence on resistant starch formation

Exopolysaccharides (EPS) were produced by four newly isolated lactic acid bacteria strains, then further extracted, separated and characterised under standardised conditions. Using a sucrose carbon source, these LAB strains belonging to Weissella confusa/cibaria produced EPS with a dextran high molecular weight fraction. The obtained yields of EPS ranged from 3.2 g/L to 47.1 g/L and outstandingly high yields were obtained using Weissella confusa/cibaria 3MI3 isolated from spontaneous spelt sourdough. After purification the influence of EPS-dextran of molar mass 3,244,000 g/mol on resistant starch formation in wheat starch pastes and pasted samples after temperature-cycled storage was examined. Size exclusion chromatography with post-column derivatisation revealed that a 1.5% share of EPS dextran limited formation of high molar mass resistant starch in starch pastes during storage. This work provides new insight on hindering resistant starch formation by using EPS, which could be efficiently produced in sourdough, thus improving the properties of sourdough bread.

Sourdough fermentation of whole and sprouted lentil flours: In situ formation of dextran and effects on the nutritional, texture and sensory characteristics of white bread

Exopolysaccharides produced in situ by lactic acid bacteria during sourdough fermentation are recognized as bread texture improvers. In this study, the suitability of whole and sprouted lentil flours, added with 25% on flour weight sucrose for dextran formation by selected strains during sourdough fermentation, was evaluated. The dextran synthesized in situ by Weissella confusa SLA4 was 9.2 and 9.7% w/w flour weight in lentil and sprouted lentil sourdoughs, respectively. Wheat bread supplemented with 30% w/w sourdough showed increased specific volume and decreased crumb hardness and staling rate, compared to the control wheat bread. Incorporation of sourdoughs improved the nutritional value of wheat bread, leading to increased total and soluble fibers content, and the aroma profile. The integrated biotechnological approach, based on sourdough fermentation and germination, is a potential clean-label strategy to obtain high-fibers content foods with tailored texture, and it can further enhance the use of legumes in novel foods.

Microbial production of value-added bioproducts and enzymes from molasses, a by-product of sugar industry

Molasses is a major by-product of sugar industry and contains 40-60% (w/w) of sugars. The world's annual yield of molasses reaches 55 million tons. Traditionally, molasses is simply discharged or applied to feed production. Additionally, some low-cost and environmentally friendly bioprocesses have been established for microbial production of value-added bioproducts from molasses. Over the last decade and more, increasing numbers of biofuels, polysaccharides, oligosaccharides, organic acids, and enzymes have been produced from the molasses through microbial conversion that possess an array of important applications in the industries of food, energy, and pharmaceutical. For better application, it is necessary to comprehensively understand the research status of bioconversion of molasses that has not been elaborated in detail so far. In this review, these value-added bioproducts and enzymes obtained through bioconversion of molasses, their potential applications in food and other industries, as well as the future research focus were generalized and discussed.

Isolation and characterization of indigenous Weissella confusa for in situ bacterial exopolysaccharides (EPS) production in chickpea sourdough

Legume-based sourdough represents a potential ingredient for the manufacture of novel baked products. However, the lack of gluten of legume flours can restrict their use due to their poor technological properties. To overcome such issue, the in situ production of bacterial exopolysaccharides (EPS) during fermentation has been proposed. In this study, an EPS-producing lactic acid bacteria for in situ production in chickpea sourdough was isolated. After several backsloppings of the spontaneously fermented chickpea flour dough, a dominant strain of Weissella confusa was isolated and identified. W. confusa Ck15 was able to produce linear dextran with 2.6% α-(1 → 3) linked branches, from sucrose. Temperature of 30 °C, dough yield of 333, and 2% of sucrose addition were used to produce fermented chickpea sourdoughs. The acidification and rheology of the sourdoughs inoculated with W. confusa Ck15, Leuconostoc pseudomesenteroides DSM 20193, as positive control, and Lactobacillus plantarum F8, as negative control, were compared. The in situ dextran production by W. confusa Ck15 fermentation led to the highest viscosity increase (5.90 Pa·s) and the highest EPS percentage in the doughs (1.49%), compared to the other doughs. The in situ dextran production represents a potential approach for improving the use of legume flour in bakery products; overall, this experiment represents a first step for the exploitation of microbial EPS for setting up a baking process for chickpea based product.

Comparison of the Functionality of Exopolysaccharides Produced by Sourdough Lactic Acid Bacteria in Bread and Steamed Bread

Exopolysaccharides (EPSs) produced by lactic acid bacteria improve the quality of bread; however, their functionality in steamed bread is unknown. This study aimed to compare the impact of EPS produced during sourdough fermentation on the quality of bread and steamed bread. Sourdoughs were fermented with EPS-producing Fructilactobacillus sanfranciscensis, Weissella cibaria, and Leuconostoc mesenteroides; Latilactobacillus sakei LS8 and chemically acidified sourdough were prepared as controls. EPS production generally enhanced the specific volume, improved the texture, and reduced the staling rate of bread. The effect of EPS on steamed bread quality was more pronounced when compared to its effect on bread quality. Remarkably, the beneficial effects of F. sanfranciscensis bread quality were largely independent of EPS formation and may relate to gluten modifications rather than EPS production. In conclusion, the direct comparison of sourdough and EPS functionality in steaming and baking provides novel insights for the optimization of commercial (steamed) bread production.

The Role of Non-Caloric Sweeteners in Sensory Characteristics of Pastry Products

The purpose of this work was to evaluate the role of non-caloric sweeteners in pastry products considering the product made with sugar as a control sample. Sensory preference and acceptability with consumers were determined through ranking test and 9-point hedonic scale respectively. The satiation and satiety were determined by the visual analogue scale (VAS). In addition, caloric intake; macronutrients; physical parameters such as yield, specific volume, hardness, cohesiveness, and gum; stability in storage time by microbiological analysis; and moisture variation of the samples were calculated. The results showed that the preference and sensory acceptability is significantly (p < 0.05) higher in the control sample; the sweeteners decreased the sensory response, but not the satiation and satiety, although these are not related to the sensory response and did not present significant differences with the control sample, except in the satiation parameter of the sample sweetened with Stevia. The physical and texture parameters highlight the best quality of the control sample and are related to the sensory response. The shelf life is also greater in the control sample, which shows that sugar contributes sweetness and other technological characteristics related to texture, stability during storage, aroma, color, and flavor, thanks to the Maillard reaction.

Influence of dextran synthesized in situ on the rheological, technological and nutritional properties of whole grain pearl millet bread

The effect of dextran produced in situ by Weissella confusa on the structure and nutrition quality of whole grain pearl millet bread containing 50% of wheat flour was investigated. NMR spectroscopy analysis indicated that the dextran formed by the strain consisted of a α-(1 → 6)-linked linear backbone and 3% α-(1 → 3) branches, and had a molar mass of 3.3 × 10⁶ g/mol. In situ production resulted in 3.5% dextran (DW) which significantly enhanced the dough extensional properties, increased the bread specific volume (∼13%) and decreased crumb firmness (∼43%), moisture loss (∼15%) and staling rate (∼10%), compared to the control millet bread. DSC analysis showed that amylopectin recrystallization was significantly reduced in the bread containing dextran. In situ dextran production altered the nutritional value of millet, leading to increased free phenolic content (∼30%) and antioxidant activity. It also markedly lowered the bread predicted glycemic index and improved in vitro protein digestibility.

Dietary fibers, prebiotics, and exopolysaccharides produced by lactic acid bacteria: potential health benefits with special regard to cholesterol-lowering effects

The gastrointestinal (GIT) microbiota, which plays a crucial role in human health, is influenced by a number of factors including diet. Consumption of specific dietary ingredients, such as dietary fibers and prebiotics, is an avenue by which the microbiota can be positively modulated. These substances may also reduce serum cholesterol levels through various mechanisms. Interest has increased in methods of reducing blood cholesterol level, because dyslipidemia is recognized as a contributory risk factor for the development of cardiovascular diseases. Several drugs have been developed for the treatment of hypercholesterolemia; however, undesirable side effects were observed, which have caused concerns about their long-term therapeutic use. Alternatively, many nonpharmacological approaches were tested to reduce elevated serum cholesterol levels. Dietary fibers and prebiotics have particularly beneficial effects on the GIT microbiome, and can also reduce serum cholesterol level through various mechanisms. Lactic acid bacteria (LAB) are potentially capable of synthesizing different polysaccharides, e.g. exopolysaccharides (EPS), which may play a role as prebiotics. LAB-based EPS have the potential to affect the gastrointestinal microbiome and reduce cholesterol. However, as dietary fibers comprise a complex group of substances with remarkably diverse structures, properties, and impacts, EPS also differ greatly and show a multitude of beneficial health effects. This review discusses the current knowledge related to the effects of dietary fibers and prebiotics on the human GIT microbiome, the prebiotic properties of EPS produced by LAB, and the health-promoting benefits of these polymers with special emphasis being given to cholesterol lowering.

Exploration of Dextran for Application as Corrosion Inhibitor for Steel in Strong Acid Environment: Effect of Molecular Weight, Modification, and Temperature on Efficiency

The possibility of utilizing dextran as a green corrosion inhibitor for steel in strong acid environment was explore using weight loss, electrochemical (electrochemical impedance spectroscopy (EIS), electrochemical frequency modulation (EFM), potentiodynamic polarization (PDP), and linear polarization (LPR)) supported with surface analysis via scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDAX), atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS) techniques. The effect of molecular weight, temperature, and modification on the inhibition efficiency of dextran was also studied. Results from all the applied techniques reveal that dextran exhibit moderate anticorrosion property toward St37-2 steel dissolution in 15% H₂SO₄ solution. Dextran with molecular weight of 100 000-200 000 g/mol (Dex 1) exhibited the highest inhibition efficiency of 51.38% at 25 °C. Based on PDP results, dextran behaved as a mixed type corrosion inhibitor. Inhibition efficiency of dextran varies inversely with molecular weight but directly with temperature. Two modification approaches, namely incorporation of silver nanoparticles (AgNPs) into dextran matrices and combination with 1 mM KI were adopted to enhance the inhibition efficiency of dextran and the approaches proved effective. The protective capability of Dex 1 has been upgraded from 51.38% to 86.82% by infusion of AgNPs and to 94.21% by combination with KI at 25 °C. Results from the study on the effect of temperature reveals that Dex 1 + KI mixture could synergistically offer 99.4% protection to St37-2 steel in 15% H₂SO₄ environment at 60 °C. Surface analysis results confirm the presence of additives molecules on the studied metal surface. XPS results disclose that AgNPs are in oxide form while iodide ions are in the form of triiodide and pentaiodide ions on the metal surface. Modified dextran is a promising candidate for application as corrosion inhibitor in acid induced corrosive environment.