Effects of heat-moisture, autoclaving, and microwave treatments on physicochemical properties of proso millet starch

Effect of sowing date on physicochemical properties of waxy and non-waxy proso millet (Panicum miliaceum L.) starches

In this experiment, waxy (Shuzi, P1) and non-waxy (Ningmei No. 14, P2) proso millet were used as experimental materials to study the quality changes of waxy and non-waxy proso millet in different sowing dates as well as the differences in the physical and chemical properties of starch, such as starch morphological structure, crystal structure and gelatinization properties. The results showed that with the postponement of the sowing date, the total starch contents of P1 and P2 decreased by 2 % - 7.28 % and 3.26 % - 8.23 %, respectively, and the protein contents decreased by 0.1 % - 9.91 % and 2.52 % - 5.03 %, respectively. Compared with B1, B3 - B5 reduced the amylose content of P1 by 15.21 % - 26.80 %. With the postponement of the sowing date, the breakdown (BD) of P1 increased by 4.68-22.79 %, while the trough viscosity (TV) and final viscosity (FV) decreased by 2.50 % - 17.43 % and 2.58 % - 9.21 %, respectively. The peak viscosity (PV), TV, BD and FV of P2 increased by 10.33 % - 36.95 %, 9.31 % - 19.86 %, 12.68 % - 81.07 % and 5.69 % - 36.46 %, respectively, with the postponement of the sowing date. The sowing date also affected the volume distribution of proso millet grains. This study clarified the influence of sowing date on the quality of proso millet grains and the physical and chemical properties of starch, providing a theoretical basis for improving the high-yield and high-quality cultivation techniques of proso millet grains and the deep processing of products.

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.

New insights into influencing the extraction efficiency of tigernut oil: Impact of heat on oil absorption and enzymatic hydrolysis of tigernut starch in a starch-protein-oil model system

Tigernut is a potential source of valuable edible oil; however, current oil extraction techniques are inefficient. We assessed high temperature-induced variations in oil absorption and enzymatic hydrolysis of tigernut starch (TS) in the presence of protein to explore the intrinsic reasons for the low oil extraction from tigernut. The results showed that, due to high temperature and the presence of protein, an increase in the volume mean diameters and agglomeration of TS granules occurred. As the temperature increased (80-140 °C), the relative crystallinity (19.09 %-24.40 %) of the long-range ordered structure and the orderliness of the short-range ordered structure increased, the total oil absorption (TOA: 0.25-0.19 g oil/g sample) decreased, and the starch-lipid complex index (2.56 %-24.61 %) increased. With increasing temperature in the range of 170-200 °C, the short-range ordered structure of TS became more compact, and the TOA (0.18-0.14 g oil/g sample) and the starch-lipid complex index (24.61 %-5.64 %) decreased. Changes in the structure of TS led to an increase and then a decrease in its thermal stability, an enhancement of the gel network structure, and a weakening of enzymatic hydrolysis. Results can help reveal the oil absorption mechanism of TS and regulate its physicochemical properties for the efficient extraction of tigernut oil.

An overview on the dry heat treatment (DHT) for starch modification: Current progress and prospective applications

Starch plays a pivotal role in numerous applications, making the enhancement of its functionality through physical processes increasingly important. Dry heat treatment (DHT) is a straightforward and eco-friendly technique that significantly improves starch characteristics and boosts food quality. This method has emerged as a focal point in starch modification research in recent years. This paper reviews current studies on the DHT of starches from various botanical sources, presenting key concepts and methodologies while delving into the impacts and mechanisms of DHT on the structural and physicochemical properties of starches. Furthermore, it elaborates on how additional components, such as ionic gums, amino acids, and sugars, can enhance the functionality of starches modified by DHT. Additionally, this review discusses the practical applications of dry heat-modified starches in the food industry, aiming to offer valuable insights for ongoing research and potential applications in enhancing food quality and functionality through innovative starch modifications.

Yield, physicochemical properties and in vitro digestibility of starch isolated from defatted meal made from microwaved tigernut (Cyperus esculentus L.) tubers

In this work, the effects of microwave treatment (MDT) of tigernut tubers at 540 W for 140, 180, 220, 240 s on the yield, physicochemical properties and in vitro digestibility of tigernut starch (TS) were firstly investigated. MDT significantly reduced the crystallinity and double helix structures of the starch, without altering its native A-type crystal structure. After microwaving for 140 s and 180 s, the extraction yield of TS was significantly increased from 14.92 % to 16.68 %, and a dense gel network structure was found by rheological analysis. In vitro digestion results indicated that the microwaved TS contained more content of rapidly digestible starch (RDS, 76.10 %-80.74 %) but lower slowly digestible starch (SDS, 2.85 %-5.78 %) and resistant starch (RS, 14.94 %-18.12 %); in other words, microwaving increased the in vitro digestibility of TS. This work elucidated the essential features of the response of tigernut starch to microwave treatment, and provided a basic understand of the digestibility of tigernut starch under microwave treatment, making it more suitable for industrial applications.

The Quality and Starch Digestibility of Multi-Grain Noodles Are Regulated by the Additive Amount of Dendrobium Officinale

Dendrobium officinale (DO) is a well-known medicinal and edible plant, yet its impact on the quality of noodles has been infrequently reported. In this study, DO was incorporated into multi-grain flour in varying proportions (0, 2, 4, 6, 8%) to prepare noodles, and their quality was assessed. The percentage increase in DO decreased the cooking loss, whiteness, appearance, and taste of the noodles while simultaneously enhancing their water absorption, adhesiveness, smoothness, and starch digestion resistance. Lower supplemental levels of DO (2-4%) facilitated the water absorption of protein and the formation of a dense and extensive protein network surrounding the partially gelatinized starch, which was characterized by higher relative crystallinity. The highest sensory score (77.4) and greatest content of slowly digestible starch content (38%) were observed in the noodles containing 4% DO. Conversely, higher percentages of DO (6-8%) diluted and compromised the protein network in the cooked noodles, leading to water migration from protein to starch. The excessive polysaccharides from DO tended to complex with fully gelatinized starch, promoting starch aggregation and interactions between starch and non-starch components. This ultimately resulted in the highest adhesiveness and resistant starch content (34%) in the cooked noodles with 8% DO. These findings provide a reference for enhancing noodle quality by regulating the amount of DO added, thereby promoting the application of DO in cereal-based food products.

Sequential effects of autoclaved heat treatment and electron beam irradiation on acorn starch: Multiscale structural differences and related mechanisms

In this study, the differences in the modification effects and related mechanisms of different times (20 and 40 min) of autoclaved heat (AH) treatment and different doses (2 and 4 kGy) of electron beam irradiation (EBI) in different sequences of effects on acorn starch were investigated. The results showed that both AH and EBI reduced the amylose content (22.70 to 19.59%) and enthalpy (10.28 to 1.84%) of starch but increased the resistant starch content (53.69 to 64.11%). AH treatment made the crystalline regions of the residual starch granules denser, which was resistant to the action of amylase enzymes. EBI degraded the long chain of starch, which increased the solubility. Notably, EBI pretreatment improves the reactive sites by inducing depolymerization and disorder in starch internal structure, thus increasing the modification extent of AH-modified starch, forming starch with lower viscosity, better hydration, and digestibility resistance, therefore being used as an ingredient for functional foods.

Exploring the remarkable effects of microwave treatment on starch modification: From structural evolution to changed physicochemical and digestive properties

As one of the crucial components of the food system, starch can be hydrolyzed into glucose after gastrointestinal digestion, so regulating its digestive properties is vital for maintaining health. Microwaves can promote the rearrangement of intramolecular structure of starch, thus improving its physicochemical properties, enhancing its slowly digestible features, and expanding its scope of application. This review zooms in describing recent research results concerning the effects of microwave treatment on the multi-scale structure and physicochemical properties of starch and summarizing the patterns of these changes. Furthermore, the changes in starch structure, resistant starch content, and glycemic index after digestion are pointed out to gain an insight into the enhancement of starch slowly digestible properties by microwave treatment. The resistance of starch to enzymatic digestion may largely hinge on the specific structures formed during microwave treatment. The multi-level structural evolutions of starch during digestion endow it with the power to resist digestion and lower the glycemic index. The properties of starch dictate its application, and these properties are highly associated with its structure. Consequently, understanding the structural changes of microwave-modified starch helps to prepare modified starch with diversified varieties and functional composites.

Modern and conventional processing technologies and their impact on the quality of different millets

Millet, the highly sustainable crop for farming and combating hunger, has recently regained a resurgence in popularity as people seek more sustainable and nutrient-dense alternatives. International organizations and research institutions have advocated for increased millet production and consumption by introducing novel technologies and machinery in response to global food security and climate change challenges. This review aims to identify the impact of modern and conventional processing technologies on the quality of different millets. A comprehensive analysis of research reviews reveals that double-stage and tabletop centrifugal dehullers, infrared roasting, pulsed light, ultrasound, high-pressure processing methods, fortification, and encapsulation are optimal for nutrient retention in various millets. Extrusion technology application in millet processing has created a diverse range of value-added products with extended shelf stability. Emphasis is needed to develop robust promotion and distribution channels and establish an export promotion forum involving all stakeholders to promote and diversify millet-based products and technologies.

Rice starch modification by thermal treatments with avocado oil: Autoclave versus microwave methods

This study aimed to evaluate the physical and chemical alterations in rice starch modified by heat-moisture treatment (HMT) using an autoclave and a microwave, in association with avocado oil (AO), and evaluate the effects on thermal and structural properties, in vitro digestibility, and estimated glycemic index (eGI). Samples were adjusted to 30 % (w/w) moisture and 2, 4 and 8 % AO. HMT was conducted at 110 °C for 1 h in the autoclave (A0%, A2%, A4%, and A8%) and at 50 °C for 3 min in the microwave (M0%, M2%, M4%, and M8%). Both procedures did not alter the starch crystallinity pattern (type-A). Pasting viscosity, setback, relative crystallinity, and gelatinisation enthalpy decreased as the AO content increased in both HMT processes. The M8% showed reduced digestibility, decreased eGI (72.99, p < 0.05), and lower starch hydrolysis concentration (62.75 %, p < 0.05). The application of HMT with the addition of AO may be an interesting process for obtaining resistant starch since its content increased after both treatments (A8%, M4%, and M8%). The microwave process proved efficient, making it possible to use a lower temperature, less time, and less energy for modification and obtain starches with improved characteristics.

Evaluating the effects of time-dependent drying and pressure heat treatments on the variation of physicochemical and rheological properties of suran starch

Recent research developments have shed light on hydrothermal treatment as a commonly employed method for physical modifications. Surprisingly, there is a scarcity of studies investigating the impact of time variation which is a critical process parameter. Therefore, it is important to closely monitor the critical process parameters throughout the process. Hence, the present study investigates the influence of time-dependent hydrothermal modifications like dry heat (DH) and pressure heat (AT) on Suran starch, focusing on the physicochemical and rheological properties. Over time, the modified starches showed increased swelling and solubility power due to intermolecular hydrogen bond disruption. Prolonged heat exposure made starch granules more susceptible to water absorption, enhancing their swelling capacity. Rheological analysis revealed time-dependent shear-thinning behaviour, with modified starches showing improved resistance to shear stress compared to native starch. Extended heat treatment led to structural rearrangements in starch granules, resulting in increased entanglement and higher viscosity, contributing to improved mechanical properties. Interestingly, the AT-25 starch sample exhibited the highest elasticity, indicating enhanced structural rigidity under high shear conditions. The time-dependent alterations due to pressure treatments improved the functionalities and structural integrity of modified Suran starch. These findings highlight the positive impact of time-dependent heat treatment modifications on Suran starch, making it a valuable resource for various industrial applications. Enhancing the industrial viability of underutilized Suran starch could contribute significantly to meeting the demand for starch in various industries.

Impact of high temperature on microstructural changes and oil absorption of tigernut (Cyperus esculentus L.) starch: Investigations in the starch-oil model system

This study was to explore the internal reasons for the changes in oil absorption performance of tigernut starch (TS) by revealing the high-temperature induced variations of structural and functional properties of TS. The results showed that as the temperature increased from 80 °C to 140 °C, the degree of starch gelatinization increased, while the proportion of double helix structures, the total proportion of B1 and B2 chains, the relative crystallinity and the molecular weight decreased, accompanied by the fragmentation and swelling of TS granules. The oxidation of tigernut oil (TNO) led to a decrease in oil density and an increase in total polar component content. These phenomena could result in an increase of oil absorption capacity of TS and starch-lipid complex index. With further increase in temperature from 170 °C to 200 °C, the disruption of the crystalline structure and chain structure increased, resulting in the melting and disintegration of TS granules. This caused a decrease in the starch-oil contact area and capillary absorption of TNO by the TS granules. The results will contribute to revealing the effect of high-temperature induced changes in the structural and functional properties of TS on its oil absorption properties.

Pleurotus ostreatus is a promising candidate of an edible 3D printing ink: Investigation of printability and characterization

The 3D printing (3DP) technology shows great potential in the food industry, but the development of edible ink is currently insufficient. Pleurotus ostreatus (P. ostreatus) emerges as a novel promising candidate. In this study, a mixed ink was obtained by incorporating butter into P. ostreatus. The effects of different ratios of P. ostreatus and butter, as well as the influence of ink steaming were investigated on 3D printed products. The results indicated that all inks of the P. ostreatus system exhibited positive shear-thinning behavior, and the system maintained stable intermolecular hydrogen bonding when P. ostreatus powder concentration was 40 % (w/v). Furthermore, the L* value of the system was elevated for butter adding. The system with steaming exhibited superior stabilized molecular structure compared to the native system, particularly with a steaming duration of 5 min, showcasing its outstanding supporting capacity. This study suggests that P. ostreatus is a promising candidate in 3DP for the development of an edible ink that promotes innovation and nutritional food.

Exploring the formation mechanism of resistant starch (RS3) prepared from high amylose maize starch by hydrothermal-alkali combined with ultrasonic treatment

In this study, type III resistant starch (RS3) was prepared from high amylose maize starch (HAMS) using hydrothermal (RS-H), hydrothermal combined ultrasonication (RS-HU), hydrothermal-alkali (RS-HA), and hydrothermal-alkali combined ultrasonication (RS-HAU). The role of the preparation methods and the mechanism of RS3 formation were analyzed by studying the multiscale structure and digestibility of the starch. The SEM, NMR, and GPC results showed that hydrothermal-alkali combined with ultrasonication could destroy the granule structure and α-1,6 glycosidic bond of HAMS and reduce the molecular weight of HAMS from 195.306 kDa to 157.115 kDa. The other methods had a weaker degree of effect on the structure of HAMS, especially hydrothermal and hydrothermal combined ultrasonication. The multiscale structural results showed that the relative crystallinity, short-range orderliness, and thermal stability of RS-HAU were significantly higher compared with native HAMS. In terms of digestion, RS-HAU had the highest RS content of 69.40 %. In summary, HAMS can generate many short-chain amylose due to structural damage, which rearrange to form digestion-resistant crystals. With correlation analysis, we revealed the relationship between the multiscale structure and the RS content, which can be used to guide the preparation of RS3.

Atmospheric pressure pin-to-plate cold plasma effect on physicochemical, functional, pasting, thermal, and structural characteristics of proso-millet starch

The present work aimed to study the influence of atmospheric pressure pin-to-plate cold plasma on the physicochemical (pH, moisture, and amylose content), functional (water & oil binding capacity, solubility & swelling power, paste clarity on storage, pasting), powder flow, thermal and structural (FTIR, XRD, and SEM) characteristics at an input voltage of 170-230 V for 5-15 min. The starch surface modification by cold plasma was seen in the SEM images which cause the surge in WBC (1.54 g/g to 1.93 g/g), OBC (2.22 g/g to 2.79 g/g), solubility (3.05-5.38% at 70 °C; 37.11-52.98% at 90 °C) and swelling power (5.39-7.83% at 70 °C; 25.67-35.33% at 90 °C) of starch. Reduction in the amylose content (27.82% to 25.07%) via plasma-induced depolymerization resists the retrogradation tendency, thereby increasing the paste clarity (up to ̴ 39%) during the 5 days of refrigerated storage. However, the paste viscosity is reduced after cold plasma treatment yielding low-strength starch pastes. The relative crystallinity of starch increased (37.35% to 45.36%) by the plasma-induced fragmented starch granules which would aggregate and broaden the gelatinization temperature, but these starch fragments reduced the gelatinization enthalpy. The fundamental starch structure is conserved as seen in FTIR spectra. Thus, cold plasma aids in the production of soluble, low-viscous, stable, and clear paste-forming depolymerized proso-millet starch.

Proso Millet (Panicum miliaceum L.) as Alternative Source of Starch and Phenolic Compounds: A Study on Twenty-Five Worldwide Accessions

Proso millet has been proposed as an effective anti-diabetic food thanks to the combined action of polyphenols and starch. This study aimed to characterize the chemical composition of twenty-five accessions, in order to enhance this cereal as an alternative to available starch for food applications or to propose new food ingredients with health benefits. Proso millet contained a high percentage of starch, reaching values of 58.51%. The amylose content showed high variability, with values ranging from 1.36 to 42.70%, and significantly higher values were recorded for the white accessions than for the colored ones. High-resistant starch content (13.41-26.07%) was also found. The HPLC-MS analysis showed the same phenolic pattern in all the samples. Cinnamic acids are the most abundant compounds and significant differences in their total content were found (0.69 to 1.35 mg/g DW), while flavonoids were only detected in trace amounts. Statistical results showed significantly higher antiradical activity in the colored accessions than in the white ones.

The research advance of resistant starch: structural characteristics, modification method, immunomodulatory function, and its delivery systems application

Resistant starch, also known as anti-digestion enzymatic starch, which cannot be digested or absorbed in the human small intestine. It can be fermented in the large intestine into short-chain fatty acids (SCFAs) and metabolites, which are advantageous to the human body. Starches can classify as rapidly digestible starch (RDS), slowly digestible starch (SDS), and resistant starch (RS), which possess high thermal stability, low water holding capacity, and emulsification characteristics. Resistant starch has excellent physiological functions such as stabilizing postprandial blood glucose levels, preventing type II diabetes, preventing intestinal inflammation, and regulating gut microbiota phenotype. It is extensively utilized in food processing, delivery system construction, and Pickering emulsion due to its processing properties. The resistant starches, with their higher resistance to enzymatic hydrolysis, support their suitability as a potential drug carrier. Therefore, this review focuses on resistant starch with structural features, modification characteristics, immunomodulatory functions, and delivery system applications. The objective was to provide theoretical guidance for applying of resistant starch to food health related industries.

White finger millet starch: Hydrothermal and microwave modification and its characterisation

White finger millet (WFM) starch was modified by hydrothermal (HS) and microwave (MS) methods. Modification methods had a significant change in the b* value observed in the HS sample, and it caused the higher chroma (∆C) value. The treatments have not significantly changed the chemical composition and water activity (aw) of native starch (NS) but reduced the pH value. The gel hydration properties of modified starch enhanced significantly, especially in the HS sample. The least NS gelation concentration (LGC) of 13.63 % increased to 17.74 % in HS and 16.41 % in MS. The pasting temperature of the NS got reduced during the modification process and altered the setback viscosity. The starch samples exhibit the shear thinning behavior and reduce starch molecules' consistency index (K). FTIR results exhibit that the modification process highly altered the short-range order of starch molecules more than the double helix structure. A significant reduction in relative crystallinity was observed in the XRD diffractogram, and the DSC thermogram depicts the significant change in the hydrogen bonding of starch granules. It can be inferred that the HS and MS modification method significantly alters the properties of starch, which can increase the food applications of WFM starch.

A Review on Isolation, Characterization, Modification, and Applications of Proso Millet Starch

Proso millet starch (PMS) as an unconventional and underutilized millet starch is becoming increasingly popular worldwide due to its health-promoting properties. This review summarizes research progress in the isolation, characterization, modification, and applications of PMS. PMS can be isolated from proso millet grains by acidic, alkaline, or enzymatic extraction. PMS exhibits typical A-type polymorphic diffraction patterns and shows polygonal and spherical granular structures with a granule size of 0.3-17 µm. PMS is modified by chemical, physical, and biological methods. The native and modified PMS are analyzed for swelling power, solubility, pasting properties, thermal properties, retrogradation, freeze-thaw stability, and in vitro digestibility. The improved physicochemical, structural, and functional properties and digestibility of modified PMS are discussed in terms of their suitability for specific applications. The potential applications of native and modified PMS in food and nonfood products are presented. Future prospects for research and commercial use of PMS in the food industry are also highlighted.

Study of unripe and inferior banana flours pre-gelatinized by four different physical methods

This study aimed to prepare the pre-gelatinized banana flours and compare the effects of four physical treatment methods (autoclaving, microwave, ultrasound, and heat-moisture) on the digestive and structural characteristics of unripe and inferior banana flours. After the four physical treatments, the resistant starch (RS) content values of unripe and inferior banana flours were decreased from 96.85% (RS2) to 28.99-48.37% (RS2 + RS3), while C∞ and k values were increased from 5.90% and 0.039 min^-1 to 56.22-74.58% and 0.040-0.059 min^-1, respectively. The gelatinization enthalpy (ΔHg) and I_1047/1022 ratio (short-range ordered crystalline structures) were decreased from 15.19 J/g and 1.0139 to 12.01-13.72 J/g, 0.9275-0.9811, respectively. The relative crystallinity decreased from 36.25% to 21.69-26.30%, and the XRD patterns of ultrasound (UT) and heat-moisture (HMT) treatment flours maintained the C-type, but those samples pre-gelatinized by autoclave (AT) and microwave (MT) treatment were changed to C + V-type, and heat-moisture (HMT) treatment was changed to A-type. The surface of pre-gelatinized samples was rough, and MT and HMT showed large amorphous holes. The above changes in structure further confirmed the results of digestibility. According to the experimental results, UT was more suitable for processing unripe and inferior banana flours as UT had a higher RS content and thermal gelatinization temperatures, a lower degree and rate of hydrolysis, and a more crystalline structure. The study can provide a theoretical basis for developing and utilizing unripe and inferior banana flours.

The role and mechanism of electron beam irradiation in glutaric anhydride esterified proso millet starch: Multi-scale structure and physicochemical properties

To investigate the effect of electron beam irradiation (EBI) pretreatment on the multiscale structure and physicochemical properties of esterified starch, this study used EBI pretreatment to prepare glutaric anhydride (GA) esterified proso millet starch. GA starch did not show the corresponding distinct thermodynamics peaks. However, it had a high pasting viscosity and transparency (57.46-74.25 %). EBI pretreatment increased the degree of glutaric acid esterification (0.0284-0.0560) and changed its structure and physicochemical properties. EBI pretreatment disrupted its short-range ordering structure, reducing the crystallinity, molecular weight and pasting viscosity of glutaric acid esterified starch. Moreover, it produced more short chains and increased the transparency (84.28-93.11 %) of glutaric acid esterified starch. This study could offer a rationale for using EBI pretreatment technology to maximize the functional properties of GA modified starch and enlarge its implementation in modified starch.

Effect of heat-moisture treatment on the physicochemical properties and digestibility of proso millet flour and starch

Proso millet flour (PMF) and starch (PMS) were subjected to heat-moisture treatment (HMT) at 25 % moisture content and 110 °C for 4 h. The effects of HMT on physicochemical and structural properties and in vitro digestibility of PMF and PMS were analyzed. After HMT, SEM showed aggregation and damage to the surface of starch granules, while CLSM showed proteins wrapped around the granules. The amylopectin chain length distribution (CLD) remained unchanged in PMF and PMS after HMT, indicating intact covalent bonds between glucose units. HMT decreased the swelling power, solubility, viscosity of the paste, and gelatinization enthalpy and increased the pasting temperature and gelatinization temperature of PMF and PMS. HMT changed the XRD pattern of PMF from A to A + V type starches, whereas that of PMS remained unchanged. FTIR study showed an increase in the degree of short-range molecular order of PMF and PMS after HMT. In vitro digestibility evaluation showed that the rapidly (RDS) and slowly digestible starch (SDS) contents of PMF and PMS increased, whereas the resistant starch (RS) content decreased after HMT. HMT flour and starch have suitable properties for use in a wide range of food products, from canned to frozen, as well as non-food products.

Exploring the underutilized novel foods and starches for formulation of low glycemic therapeutic foods: a review

Rising incidences of life-style disorders like obesity, diabetes and cardiovascular diseases are a matter of concern coupled with escalated consumption of highly refined and high energy foods with low nutrient density. Food choices of consumers have witnessed significant changes globally with rising preference to highly processed palatable foods. Thus, it calls food scientists, researchers and nutritionists' attention towards developing and promoting pleasant-tasting yet healthy foods with added nutritional benefits. This review highlights selected underutilized and novel ingredients from different food sources and their by-products that are gaining popularity because of their nutrient density, that can be employed to improve the nutritional quality of conventionally available empty-calorie foods. It also emphasizes on the therapeutic benefits of foods developed from these understudied grains, nuts, processing by-products of grains, fruits- and vegetable-byproducts and nutraceutical starches. This review aims to draw attention of food scientists and industrialists towards popularizing the utilization of these unconventional, yet nutrient rich foods sources in improving the nutritional profile of the conventional foods lacking in nutrient density.

Study on structural characteristics, physicochemical properties, and in vitro digestibility of Kudzu-resistant starch prepared by different methods

Three different methods, including autoclaving, autoclaving-debranching, and purification, were used to prepare Kudzu-resistant starch (KRS) from Kudzu starch (KS). The physicochemical properties, such as thermodynamic properties, pasting properties, solubility, swelling, and coagulability, as well as the in vitro digestive characteristics of the three kinds of KRS were studied. The results showed that the morphology of starch granules of KRS prepared by autoclave, autoclave enzymatic hydrolysis, and purification methods was changed and the relative crystallinity was significantly decreased compared with the original starch. X-ray diffraction (XRD) showed that KRS exists in the form of C and C+V crystalline form. There was a significant increase in the pasting temperature and a remarkable decrease in the peak viscosity and the expansion degree of the KRS prepared by all three methods. The solubility of the resistant starch (RS) obtained by autoclaving-debranching and that by purification were both increased compared to that of native KS, while the solubility of the RS obtained by autoclaving was decreased. Meanwhile, the retrogradation of the three RS was also improved to varying degrees. The contents of RS in the samples were: P-KRS (71%) > DA-KRS (43%) > A-KRS (42%) > KS (9%). Simulated human in vitro digestion experiments showed that RS has stronger antidigestibility properties than native starch. Among them, the RS prepared by the purification method has stronger antidigestive properties, and it is predicted that it may have a better potential value in regulating blood glucose. These results indicated that the processing properties of KRS, especially the digestibility, are significantly improved and can be used as a new functional food ingredient, which deserves thorough study.

Study of Changes in Crystallinity and Functional Properties of Modified Sago Starch (Metroxylon sp.) Using Physical and Chemical Treatment

Sago starch has weaknesses such as low thermal stability and high syneresis. Modifications were made to improve the characteristics of native sago starch. In this study, sago starch was modified by autoclave-heating treatment (AHT), osmotic-pressure treatment (OPT), octenyl-succinic anhydride modification (OSA), and citric acid cross-linking (CA). This study aimed to examine the changes in chemical composition, crystallinity, and functional properties of the native sago starch after physical and chemical modifications. The results show that physical modification caused greater granule damage than chemical modification. All modification treatments did not alter the type of crystallinity but decreased the relative crystallinity of native starch. New functional groups were formed in chemically modified starches at a wavelength of 1700-1725 cm-1. The degree of order (DO) and degree of double helix (DD) of the modified starches were also not significantly different from the native sample, except for AHT and OPT, respectively. Physical modification decreased the swelling volume, while chemical modification increased its value and is inversely proportional to solubility. AHT and OPT starches have the best freeze-thaw stability among others, indicating that both starches have the potential to be applied in frozen food.

Verification of autoclaving-cooling treatment to increase the resistant starch contents in food starches based on meta-analysis result

Autoclaving-cooling is a common starch modification method to increase the resistant starch (RS) content. The effect of this method varies depending on the type of crop and treatment condition used. The objectives of this study were to verify the autoclaving-cooling treatment based on a meta-analysis result and to evaluate the physicochemical properties of modified starches. The meta-analysis study used 10 articles from a total of 1,293 that were retrieved using the PRISMA approach. Meta-analysis showed that the optimal treatments of autoclaving-cooling process that increase the RS content significantly, was in starch samples from the cereal group (corn, oats, rice) (SMD: 19.60; 95% CI: 9.56-29.64; p < 0.001), with water ratio 1:4 (SMD: 13.69; 95% CI: 5.50-21.87; p < 0.001), using two cycles of autoclaving-cooling (SMD: 16.33; 95% CI: 6.98-25.67; p < 0.001) and 30 min of autoclaving heating (SMD: 12.97; 95% CI: 1.97-23.97; p < 0.001) at 121°C (SMD: 12.18; 95% CI: 1.88-22.47; p < 0.001). Verification using corn flour and corn starch showed a significant increase in RS contents from 15.84 to 27.78% and from 15.27 to 32.53%, respectively, and a significant decrease in starch digestibility from 67.02 to 35.74% and from 76.15 to 28.09%, respectively. Treated sample also showed the pasting profile that was stable under heating and stirring.

The Process of Pasting and Gelling Modified Potato Starch with LF-NMR

Currently, society expects convenience food, which is healthy, safe, and easy to prepare and eat in all conditions. On account of the increasing popularity of modified potato starch in food industry and its increasing scope of use, this study focused on improving the physical modification of native starch with temperature changes. As a result, it was found that the suggested method of starch modification with the use of microwave power of 150 W/h had an impact on the change in starch granules. The LF-NMR method determined the whole range of temperatures in which the creation of a starch polymer network occurs. Therefore, the applied LF-NMR technique is a highly promising, noninvasive physical method, which allows obtaining a better-quality structure of potato starch gels.

Effect of Thermal Pretreatments on Phosphorylation of Corypha umbraculifera L. Stem Pith Starch: A Comparative Study Using Dry-Heat, Heat-Moisture and Autoclave Treatments

Talipot starch, a non-conventional starch source with a high yield (76%) from the stem pith of talipot palm (Corypha umbraculifera L.) was subjected to three different thermal treatments (dry-heat, heat-moisture and autoclave treatments) prior to phosphorylation. Upon dual modification of starch with thermal treatments and phosphorylation, the phosphorous content and degree of crosslinking significantly increased (p ≤ 0.05) and was confirmed by the increased peak intensity of P=O and P-O-C stretching vibrations compared to phosphorylated talipot starch in the FT-IR spectrum. The highest degree of crosslinking (0.00418) was observed in the autoclave pretreated phosphorylated talipot starch sample. Thermal pretreatment remarkably changed the granule morphology by creating fissures and grooves. The amylose content and relative crystallinity of all phosphorylated talipot starches significantly decreased (p ≤ 0.05) due to crosslinking by the formation of phosphodiester bonds, reducing the swelling power of dual-modified starches. Among all modified starches, dry-heat pretreated phosphorylated starch gel showed an improved light transmittance value of 28.4%, indicating reduced retrogradation tendency. Pasting and rheological properties represented that the thermal pretreated phosphorylated starch formed stronger gels that improved thermal and shear resistance. Autoclave treatment before phosphorylation of talipot starch showed the highest resistant starch content of 48.08%.

Effects of Hydrothermal Treatments on Physicochemical Properties and In Vitro Digestion of Starch

Starchy food items such as rice and potato with high carbohydrate content raise blood sugar. Hence, consuming low glycaemic foods is one tool to keep diabetes under control. In this study, potato and brown rice (Njavara rice) starches were subjected to hydrothermal treatments: heat moisture treatment (HMT) and annealing (ANN) to develop starch-based food products fit for consumption by diabetic patients. The effects of hydrothermal treatments on physicochemical properties and in-vitro enzymatic digestion of starch were determined. It was observed that hydrothermal treatments decreased the swelling power (SP)% and increased the water solubility (WS)% of the native starches. Native potato starch (PSN) showed a high SP of 80.33%, while annealed potato starch (PANN) and heat moisture treated potato starch (PHMT) showed SP reduced to 65.33% and 51.66%, respectively. Similarly, the SP % reduced from 64.33% in native brown rice (BRN) to 44.66% in annealed brown rice (BRANN) and 38.33% in heat moisture treated brown rice (BRHMT). WS % increased from 32.86% in PSN to 36.66% in PANN and 40.66% in PHMT. In BRN, the WS % increased from 14.0% to 14.66% in BRANN and 18.33% in BRHMT. Amylose content increased from 13.23% and 14.56% in PSN and BRN to 16.14% in PANN 17.99% in PHMT, 17.33% in BRANN, and 18.98% in BRHMT. The PSN crystallinity index reduced from 33.49 to 30.50% in PANN and 32.60% in PHMT. At 12 h of enzymatic digestion, it was found that the degree of hydrolysis (DoH) of PHMT (31.66%) and PANN (36.82%) reduced when compared to PSN (41.09%). Similarly, BRHMT exhibited the lowest DoH at 12 h compared to BRANN (29.24%) and BRN (35.48%). This study highlights the importance of hydrothermal treatments on starch in developing low glycaemic index commercial starch-based food products.

Study of starch aging characteristics based on Terahertz technology

Traditional methods for the determination of starch aging indicators often have a series of shortcomings such as time-consuming, high cost, large human error, damage to samples, environmental pollution, and high requirements for inspectors. Therefore, it is meaningful to find or establish a dynamic fingerprint identification pattern that can detect the aging degree of starch during the process of processing or storage quickly and accurately. It not only provides guidance for starch food processing but also saves a lot of human, material resources, and time. Terahertz technology is an emerging molecular spectroscopy technology in the 21st century. It is with low energy and basically harmless to the human body. It can also realize nondestructive testing of samples. In the experiment, the samples were prepared by the tableting method and the samples containing 20% of 50 mg samples were prepared with polyethylene as the diluent. The thickness of the samples was 1 mm and the diameter was 13 mm. The terahertz time-domain spectrometer was used to obtain the spectral information of aging starch at different aging times. After the pretreatment of the spectrum by vector normalization, first derivative, and multiple scattering correction, the prediction models of aging days, crystallinity, and resilience of aging starch were established, respectively. The determination coefficient (R 2) of the established models is all greater than 95%, indicating that the established models are highly reliable and can be used to predict the aging days, crystallinity, and retrogradation degree of starch. And the R 2 of the prediction model based on the refractive index spectrum is greater than that of the absorption coefficient spectrum. The experimental method obtains the dynamic fingerprint identification map of starch in the aging process, realizes the real-time monitoring and detection of the starch aging process, and provides an effective means for the production and processing of starch-related industries.

Effect of heat treatment and γ-irradiation on pasting, rheological, and fungal load of whole and dehulled millets

Millets are important food crops in food systems and application of physical treatments could improve the functional properties of millet-based products. Therefore, we investigated the effect of heat and γ-irradiation treatments on the pasting, rheological, and microbial load of whole and dehulled millets (sorghum, foxtail millet, and pearl millet). Moreover, similarity in treatment effect was evaluated by principal component analysis (PCA). The results revealed the significant (p < 0.05) decrease in pasting properties of whole and dehulled millets, except for pasting temperature (71.03 to 74.88 °C). Likewise, significantly (p < 0.05) decreased tendency was observed for all rheological properties, except for phase angle (0.05 to 0.30°) and yield point (13 to 5089). Samples showed a significant (p < 0.05) reduction in fungal growth (89.75 × 10⁴ to 4.46 × 10⁴ CFU/g) compared to control (110.30 × 10⁴ CFU/g). Moreover, samples individually formed 3 clusters (clusters 1: sorghum, 2: pearl millet, and 3: foxtail millet) based on pasting properties, which was confirmed by PCA. Therefore, the findings concluded that the effect of heat and γ-irradiation would be necessary to decrease pasting, rheological, and no microbial growth characteristics of dehulled and whole millets for the development of specific millet-based food products.

Insights into the structure and conformation of potato resistant starch (type 2) using asymmetrical flow field-flow fractionation coupled with multiple detectors

Insight into the structure and conformation characteristics of starch that influence its enzyme susceptibility is import for its potential application. In this study, the capacity of asymmetrical flow field-flow fractionation (AF4) coupled online with multi-angle light scatting (MALS) and differential refractive index (dRI) detectors (AF4-MALS-dRI) for monitoring of change in structure and conformation of potato starch during enzymatic hydrolysis was evaluated. The dissolution behavior of potato resistant starch (type 2) (PRS) was investigated. The effect of incubation time and amyloglucosidase concentration on the structure and conformation of potato starch was studied. The apparent density and the ratio of R_g (radius of gyration) to R_h (hydrodynamic radius) obtained from AF4-MALS-dRI were proven to be important parameters as they offer an insight into conformation of PRS at molecular level. Results suggested that gelatinization process made potato amylose molecules have a loose and random coil conformation which could contribute to an acceleration of enzymatic hydrolysis of potato starch. Furthermore, an intermediate with an elongated branched conformation was found between amylose and amylopectin populations, which may play a role in digestion property of potato starch. The results demonstrated that AF4-MALS-dRI is a powerful tool for better understanding of conformation of PRS.

Capitalizing on a double crop: Recent advances in proso millet's transition to a food crop

Across the globe, strategies to adapt food production to a changing climate as well as to unforeseen events (such as a pandemic) are needed, for example, if farmers miss planting times due to abnormal weather patterns or harvests are lost. Such food security considerations represent reasons for why proso millet deserves a more prominent place at the table. It has one of the shortest growing seasons and water requirements among cereals and is already grown in rotation with other crops, for example, in the American Midwest. Yet, most consumers in the Western world are unfamiliar with it, which limits its market potential. Introducing proso millet to consumers requires development of products with acceptable textural and sensory attributes as well as convincing selling points. These can be found in its nutritional profile, as it is a gluten-free "ancient" grain and millet-based products frequently have low glycemic indices. This review presents a synthesis of recent studies that utilized processing strategies to advance proso millet functionality. Results are put into the context of the most frequently addressed compositional and functional attributes, organized in clusters. Diversity across varieties in amylose to amylopectin ratios presents an opportunity to utilize proso millet for foods with specific pasting requirements, as in bread versus pasta. Hydrothermal or pressure treatments may further adapt its functionality for baked goods. Bitterness remains an unsolved issue, even when decorticated material is used. In addition, heating dramatically lowers in vitro protein digestibility, whereas starch digestibility appears to be matrix dependent (more than raw material dependent).

Recent advances in heat-moisture modified cereal starch: Structure, functionality and its applications in starchy food systems

Cereals, one of the starch sources, have a tremendous and steady production worldwide. Starchy foods constitute the major part of daily calorie intake for humans. As a simple and green modification approach, heat-moisture treatment (HMT) could change the granular surface characteristics and size, crystalline and helical structure, as well as molecular organization of cereal starch. The changing degree is contingent on HMT parameters and botanical origin. Based on the hierarchical structure, this paper reviews functionalities of heat-moisture modified cereal starch (HMCS) reported in latest years. The functionality of HMCS could be affected by co-existing non-starch ingredients through non-covalent/covalent interactions, depolymerization or simply attachment/encapsulation. Besides, it summarizes the modulation of HMCS in dough rheology and final food products' quality. Selecting proper HMT conditions is crucial for achieving nutritious products with desirable sensory and storage quality. This review gives a systematic understanding about HMCS for the better utilization in food industry.