Optimization of resistant starch formation from high amylose corn starch by microwave irradiation treatments and characterization of starch preparations

Potential of Process-Induced Modification of Potato Starch to Modulate Starch Digestibility and Levels of Resistant Starch Type III

Starch digestibility and the content of resistant starch (RS) play a crucial role in human health, particularly in relation to glycemic responses, insulin sensitivity, fat oxidation, and satiety. This study investigates the impact of processing methods on potato starch digestibility and RS content, focusing on two modification techniques: autoclaving and high hydrostatic pressure (HHP), followed by retrogradation at different temperatures. The research employs a comprehensive approach to characterize structural changes in starch samples using X-ray diffraction (XRD), attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, and scanning electron microscopy (SEM). In turn, semi-dynamic in vitro digestion experiments based on the INFOGEST protocol were conducted to assess starch digestibility, while RS content was evaluated through enzymatic digestion of the non-RS fraction. SEM, XRD, and FTIR measurements reveal thermal processing appreciably affected starch architectures while HHP had a marginal effect. Further, the FTIR 1045/1022R ratio was found to be correlated with RS content measurements while reducing rapidly digestible starch (RDS). The findings led to the stipulation that thermal processing facilitates amylose leaching and granular disruption. In turn, retrogradation enabled the deposition of the amylose onto the disrupted structures which delineated their subsequent liability to enzymatic digestion. Conversely, HHP had minimal effects on granular architectures and amylose leaching. Overall, this research provides valuable insights for processing starch-based food products with the goal of increasing RS content, which may have significant implications for the food industry and nutritional science.

Nutrition and Gut Health: Preparation and Efficacy of Resistant Starch

Resistant starch (RS) refers to starch varieties that resist digestion by human digestive enzymes. Owing to its distinctive physicochemical attributes and functional capabilities, RS has gained a wide range of applications as a dietary fiber and prebiotic. In terms of structure and functions, RS can be categorized into five distinct types: RS1 through RS5. These types offer dietary benefits, contributing to improved colonic health, the modulation of microbial communities, the reduction in gallstone formation, the enhancement of mineral absorption, and alterations in fat oxidation potential. From a technical standpoint, RS can be manufactured through an array of physical, enzymatic, and chemical modifications. This paper presents a comprehensive review of the existing literature, summarizing the classification, structural features, raw material origins, preparation methodologies, and functionalities of RS. Furthermore, new production technologies and applications of RS, such as 3D printing, provide valuable insights.

Recent Advances in Physical Processing Techniques to Enhance the Resistant Starch Content in Foods: A Review

The physical modification of starch to produce resistant starch (RS) is a viable strategy for the glycemic index (GI) lowering of foods and functionality improvement in starchy food products. RS cannot be digested in the small intestine but can be fermented in the colon to produce short-chain fatty acids rather than being broken down by human digestive enzymes into glucose. This provides major health advantages, like better blood sugar regulation, weight control, and a lower chance of chronic illnesses. This article provides a concise review of the recent developments in physical starch modification techniques, including annealing, extrusion, high-pressure processing, radiation, and heat-moisture treatment. Specifically, the focus of this paper is on the alteration of the crystalline structure of starch caused by the heat-moisture treatment and annealing and its impact on the resistance of starch to enzymatic hydrolysis, as well as the granular structure and molecular arrangement of starch caused by extrusion and high-pressure processing, and the depolymerization and crosslinking that results from radiation. The impacts of these alterations on starch's textural qualities, stability, and shelf life are also examined. This review demonstrates how physically modified resistant starch can be used as a flexible food ingredient with both functional and health benefits. These methods are economically and ecologically sustainable since they successfully raise the RS content and improve its functional characteristics without the need for chemical reagents. The thorough analysis of these methods and how they affect the structural characteristics and health advantages of RS emphasizes the material's potential as an essential component in the creation of functional foods that satisfy contemporary dietary and health requirements.

High-pressure pasting performance and multilevel structures of short-term microwave-treated high-amylose maize starch

Microwave treatment is an environmentally friendly method for modification of high-amylose maize starch (HAMS). Here, the effects of short-time (≤120 s) microwave treatment on the structure and pasting of two types of HAMSs, Gelose 50 (HAMSI) and Gelose 80 (HAMSII), with apparent amylose content (AAC) of 45 % and 58 %, respectively, was studied using a multiscale approach including X-ray scattering, surface structures, particle size distribution, molecular size distributions and high temperature/pressure Rapid Visco Analysis (RVA)-4800 pasting. As compared to starch with no amylose (waxy maize starch, WMS) and 25 % amylose content (normal maize starch, NMS), HAMSI underwent similar structural and pasting changes as WMS and NMS upon microwave treatment, and it might primarily be attributed to the amylopectin fraction that was affected by cleavage of the connector chains between double helices and backbone chains, which decreased the crystallinity and thickness of the crystalline lamellae. However, the multi-scale structure of HAMSII was almost unaffected by this treatment. The pasting properties of fully gelatinized HAMSI starch showed a decrease in RVA-4800 peak and final viscosities after microwave treatment. In contrast, for HAMSII starch, the microwave treatment led to an increase in these viscosities. The combined results highlight the influence of varying AAC on the effects of microwave-mediated modification, leading to diverse alterations in the structure and functionality of starches.

Ionizing and nonionizing radiations can change physicochemical, technofunctional, and nutritional attributes of starch

Challenges for the food/non-food applications of starch mostly arise from its low stability against severe processing conditions (i.e. elevated temperatures, pH variations, intense shear forces), inordinate retrogradability, as well as restricted applicability. These drawbacks have been addressed through the modification of starch. The escalating awareness of individuals toward the presumptive side effects of chemical modification approaches has engrossed the attention of scientists to the development of physical modification procedures. In this regard, starch treatment via ionizing (i.e. gamma, electron beam, and X-rays) and non-ionizing (microwave, radiofrequency, infrared, ultraviolet) radiations has been introduced as a potent physical strategy offering new outstanding attributes to the modified product. Ionizing radiations, through dose-dependent pathways, are able to provoke depolymerization or cross-linking/grafting reactions to the starch medium. While non-ionizing radiations could modify the starch attributes by changing the morphology/architecture of granules and inducing reorientation/rearrangement in the molecular order of starch amorphous/crystalline fractions.

Synthesis and Functions of Resistant Starch

Resistant starch (RS) has become a popular topic of research in recent years. Most scholars believe that there are 5 types of RS. However, accumulating evidence indicates that in addition to starch-lipid complexes, which are the fifth type of RS, complexes containing starch and other substances can also be generated. The physicochemical properties and physiologic functions of these complexes are worth exploring. New physiologic functions of several original RSs are constantly being discovered. Research shows that RS can provide health improvements in many patients with chronic diseases, including diabetes and obesity, and even has potential benefits for kidney disease and colorectal cancer. Moreover, RS can alter the short-chain fatty acids and microorganisms in the gut, positively regulating the body's internal environment. Despite the increase in its market demand, RS production remains limited. Upscaling RS production is thus an urgent requirement. This paper provides detailed insights into the classification, synthesis, and efficacy of RS, serving as a starting point for the future development and applications of RS based on the current status quo.

Effect of adding high concentrations of retrograded starch with different amylose content on the physicochemical properties and sensory attributes of Greek-style yogurt

It is well known that using retrograded starches confers many technological advantages, as well as health benefits when consumed in adequate doses; however, these properties are closely related to the type of starch and/or the treatment applied, therefore, it is of interest to add retrograded starch to popular products such as Greek yogurt. The aim of this work was to investigate the effect of adding two types of retrograded corn starch with different amylose content to a non-strained type of Greek-style yogurt. Retrograded starch from starch containing 27 % (RNS) or 70 % (RHS) amylose was added to yogurt at 0, 10, 12.5, or 15 g/100 g before storage at 4 °C for 14 d. The resistant starch (RS) content, pH, syneresis, flow behavior index, and consistency index, were measured every week. A sensory test was carried out in yogurt added with 12.5 g/100 g of retrograded starches to evaluate acceptability. Adding retrograded starch significantly reduced syneresis while increasing the consistency, firmness, and resistant starch content of the yogurt. No significant differences in general acceptance were observed in samples added with RNS when compared to control. Although a significant difference was observed after adding RHS, the acceptance of the product is still convenient. Adding a high concentration of retrograded starch could help to ensure doses enough for a prebiotic effect of RS with concentrations of 1.74 ± 0.37 to 2.32 ± 0.09 g/100 g and from 3.5 ± 0.08 to 4.21 ± 0.08 g/100 g when RNS or RHS is added while maintaining the quality characteristics of Greek-style yogurt during storage without compromising the acceptability.

High-amylose maize starch: Structure, properties, modifications and industrial applications

High-amylose maize refers to a special type of maize cultivar with a 50 %-90 % amylose content of the total starch. High-amylose maize starch (HAMS) is of interest because it possesses unique functionalities and provides many health benefits for humans. Therefore, many high-amylose maize varieties have been developed via mutation or transgenic breeding approaches. From the literature reviewed, the fine structure of HAMS is different from the waxy and normal corn starches, influencing its gelatinization, retrogradation, solubility, swelling power, freeze-thaw stability, transparency, pasting and rheological properties, and even in vitro digestion. HAMS has undergone physical, chemical, and enzymatical modifications to enhance its characteristics and thereby broaden its possible uses. HAMS has also been used for the benefit of increasing resistant starch levels in food products. This review summarizes the recent developments in our understanding of the extraction and chemical composition, structure, physicochemical properties, digestibility, modifications, and industrial applications of HAMS.

Cassava starch and chickpea flour pre-treated by microwave as a substitute for gluten-free bread additives

There is an increasing demand for gluten-free products, which are regularly made by a combination of ingredients and additives. Microwave pre-treatment of gluten-free ingredients is an alternative to food additives because it may induce changes in protein and starch functional properties. In this context, this study aimed to apply microwave treatment in cassava starch and chickpea flour, analyzing their functional and thermal properties and their ability to substitute additives in gluten-free breads, comparing them to an additive-containing bread. All formulations were analyzed regarding their physical characteristics and quality parameters. The microwave-treated ingredients showed color, thermal properties and morphology changes. The bread made with chickpea flour treated with initial moisture of 40% showed the best quality parameters when compared to the control bread. The ingredients pre-treated with microwave have shown efficiency on gluten-free bakery additives substitution, allowing the use of a clean label terminology.

Influence of corn resistant starches type III on the rheology, structure, and viable counts of set yogurt

The study intended to explore the influence of corn resistant starches type III (RS3s) prepared by autoclave, debranching, and microwave heat on the rheology, structure, and viable counts of set yogurt. The rheological analysis suggested that RS3s enhanced the elastic and viscous modulus of yogurt, and that microwave-heated RS was the most effective for improving viscoelasticity. Fitting the creep data using the Burger model showed that yogurt with microwave-heated RS increased the structural strength of yogurt, which displayed the highest instantaneous and viscoelastic deformations. The confocal laser scanning microscopy and scanning electron microscopy micrographs demonstrated that autoclaved and debranched RS3s formed large fragments and disrupted the continuity of the milk protein structure; however, microwave-heated RS evenly filled the gel network and formed an interpenetrating network with proteins. The bacterial count and acidity of yogurt indicated that microwave-heated and debranched RS3s promoted the growth of lactic acid bacteria and accelerated the fermentation process of yogurt. The results of this study demonstrated that microwave-heated RS is a favorable supplement to the microstructure and rheological properties of yogurt compared with autoclaved and debranched RS3s.

Effects of Hydrothermal and Microwave Dual Treatment and Zein on the Enzymolysis of High Amylose Corn Starch

Resistant starch (RS) type 2-high-amylose corn starch (HACS) was subjected to simultaneous hydrothermal (25% moisture content, 90 °C for 12 h) and microwave (35% moisture content, 40 W/g microwaving for 4 min) treatment and zein (at a zein to treated starch ratio of 1:5, 50 °C for 1 h) to improve its resistance to enzymolysis. Scanning electron microscopy (SEM) highlighted the aggregation and adhesion of the composite. The average particle size of the composite (27.65 μm) was exceeded that of both the HACS (12.52 μm) and the hydrothermal and microwave treated HACS (hydro-micro-HACS) (12.68 μm). The X-ray diffraction results revealed that the hydro-micro-HACS and composite remained B-type, while their crystallinity significantly decreased to 16.98% and 12.11%, respectively. The viscosity of the hydro-micro-HACS and composite at 50 °C was 25.41% and 35.36% lower than that of HACS. The differential scanning calorimetry (DSC) results demonstrated that the composite displayed a new endothermic peak at 95.79 °C, while the weight loss rate and decomposition temperature were 7.61% and 2.39% lower than HACS, respectively. The RS content in HACS, the hydro-micro-HACS, and composite was 47.12%, 57.28%, and 62.74%, respectively. In conclusion, hydrothermal and microwave treatment combined with zein provide an efficient physical strategy to enhance the RS type 2-HACS.

Microwave technology: a novel approach to the transformation of natural metabolites

Microwave technology is used throughout the world to generate heat using energy from the microwave range of the electromagnetic spectrum. It is characterized by uniform energy transfer, low energy consumption, and rapid heating which preserves much of the nutritional value in food products. Microwave technology is widely used to process food such as drying, because food and medicinal plants are the same organisms. Microwave technology is also used to process and extract parts of plants for medicinal purposes; however, the special principle of microwave radiation provide energy to reaction for transforming chemical components, creating a variety of compounds through oxidation, hydrolysis, rearrangement, esterification, condensation and other reactions that transform original components into new ones. In this paper, the principles, influencing factors of microwave technology, and the transformation of natural metabolites using microwave technology are reviewed, with an aim to provide a theoretical basis for the further study of microwave technology in the processing of medicinal materials.

Formation of type 3 resistant starch from mechanical activation-damaged high-amylose maize starch by a high-solid method

This study focused on constructing a high-solid reaction system to prepare type 3 resistant starch (RS₃) with high-amylose maize starch as raw material by mechanical activation (MA) pretreatment combined with thermal and freeze-thaw treatments. MA pretreatment effectively destroyed the crystal structure and molecular structure of native starch. MA damaged starch with a certain viscosity could form dough with a small amount of water to construct a starch continuous phase system. RS content increased with the damage levels of starch as the formation of double helix structure, attributed to that the molecules of MA damaged starch could be easy to move and form recrystallization structure. Thermal and freeze-thaw treatments contributed to strong interaction of starch-water and the re-formation of internal crystal structure of MA damaged starch to form RS₃. This study provides insight into the development of a highly effective approach for large scale production of resistant starch.

Capsaicin stability and bio-accessibility affected by complexation with high-amylose corn starch (HACS)

Delivery of pungent bioactives such as capsaicin from hot peppers is a scientific, technological and sensorial challenge. While capsaicin intake is positively related to various bowel diseases, its high pungency and instability upon digestion generate a problem in its delivery to the target organ. Helical V-amylose architectures have been shown to be a possible nano-sized delivery vehicle for such hydrophobic bioactives. This study sought to entrap capsaicin (CAP) within high amylose corn starch (HACS), quantitate and optimize the encapsulation efficiency and other techno-functional properties as well as evaluate the release of capsaicin in the duodenum. By adapting an acidification protocol, HACS was processed to form nanocapsules loaded with capsaicin. The capsaicin content and loading ratio were optimized to 44.0% (±0.4) and 1 : 1 (CAP : HACS, w/w), respectively. AFM and XRD measurements of the complexes confirmed the formed nanocapsules to be V-type crystals with a 1 : 10 (CAP : HACS, w/w) loading ratio showing the highest level of crystallinity. Laser scattering measurements demonstrated an increase in poly-dispersity as the loading ratio increased as well as a higher surface-area diameter. Scanning electron microscopy (SEM) revealed the formation of irregular circular starch inclusion complexes upon acidification treatment. Finally, an in vitro digestion model was utilized to ascertain capsaicin release under gastro-intestinal conditions that coincides with complex degradation under digestive conditions. Both adult and elderly in vitro digestion models were applied, showing the effect of age on the nanocapsule degradation and capsaicin bioaccessibility. Overall, this work provides practical information about the use of HACS for nano-encapsulation of capsaicin and its controlled release under digestive conditions, and provides insight regarding the correlation between nanocomplex characteristics and the consumer physiology. Such a nano-encapsulation platform could prove to be useful in the fortification and supplementation of starchy foods with challenging bioactives, such as the pungent capsaicin.

Optimization of the autoclave preparation process for improving resistant starch content in rice grains

The autoclave preparation process to increase the content of resistant starch (RS) in rice grains was optimized, and the results showed that the optimal preparation process was obtained with a water content of 41.63%, a pH of 5.95, an autoclave time of 60.96 min, and a refrigeration time of 17.11 hr. Under these conditions, the theoretical value of RS content in rice grains reached 17.57%. After autoclaving, the estimated glycemic index (EGI) in rice grains was reduced from 78.35 to 66.08 measured after cooking, suggesting that autoclaving was capable of increasing the RS content in rice grains and reducing its EGI value. These results may help spark new concepts and methods for the development of specialized foods for specific populations, such as people with diabetes.

The preparation, formation, fermentability, and applications of resistant starch

Resistant starch (RS) cannot be digested in the small intestine but can be fermented by microflora in the colon. To meet the demand for RS, effective methods and advanced equipment for preparing RS have emerged, but further development is needed. RS contents are affected by different prepared methods, starch source and certain nutrients such as protein, phenols, and hydrocolloids interacted with RS. As a beneficial fermentation substrate, RS modifies and stabilizes the intestinal flora to balance the intestinal environment and improve intestinal tract health and function. RS is also a kind of ingredient with potential physiological function, even better than that dietary fiber, but also in terms of providing various health benefits. RS has good food-processing characteristics as well and can thus be widely used in the food industry.

Particle size and physical-chemical characteristics of hydrothermally treated cornmeal on resistant starch content

The influence of particle size and chemical composition of three different cornmeals on the resistant starch (RS) content formed during the hydrothermal treatment was studied. The changes in reducing sugars and phenolic acids in different fractions caused by the hydrothermal treatment were correlated with RS content. The cornmeal with smaller particle size had higher RS content (202 mg/g). The hydrothermal treatment promoted a reduction in the total reducing sugars (46.7-84.5%), availability of free phenolic acids (256.7%) and reduction of the bound phenolic acids (71.1%). The correlation between RS contents and phenolic acids was determined by multivariate statistics and principal component analysis (PCA) showed that hydroxybenzoic and ferulic acids influence the formation of RS similar to type 5, amylose-phenol complex. The texture profile parameters (TPA) of cornmeal were negatively correlated with RS and differential scanning calorimetry (DSC) analysis showed consistency with this behavior.

Moisture content during extrusion of oats impacts the initial fermentation metabolites and probiotic bacteria during extended fermentation by human fecal microbiota

Extrusion exposes flour components to high pressure and shear during processing, which may affect the dietary fiber fermentability by human fecal microbiota. The objective of this study was to determine the effect of flour moisture content during extrusion on in vitro fermentation properties of whole grain oats. Extrudates were processed at three moisture levels (15%, 18%, and 21%) at fixed screw speed (300rpm) and temperature (130°C). The extrudates were then subjected to in vitro digestion and fermentation. Extrusion moisture significantly affected water-extractable β-glucan (WE-BG) in the extrudates, with samples processed at 15% moisture (lowest) and 21% moisture (highest) having the highest concentration of WE-BG. After the first 8h of fermentation, more WE-BG remained in fermentation media in samples processed at 15% moisture compared with the other conditions. Also, extrusion moisture significantly affected the production of acetate, butyrate, and total SCFA by the microbiota during the first 8h of fermentation. Microbiota grown on extrudates processed at 18% moisture had the highest production of acetate and total SCFA, whereas bacteria grown on extrudates processed at 15% and 18% moisture had the highest butyrate production. After 24h of fermentation, samples processed at 15% moisture supported lower Bifidobacterium counts than those produced at other conditions, but had among the highest Lactobacillus counts. Thus, moisture content during extrusion significantly affects production of fermentation metabolites by the gut microbiota during the initial stages of fermentation, while also affecting probiotic bacteria counts during extended fermentation.