Proso-millet starch: Properties, functionality, and applications

Spatially selective catalysis of OSA starch for preparation of Pickering emulsions with high emulsification properties

The traditional strategies of chemical catalysis and biocatalysis for producing octenyl succinic anhydride modified starch can only randomly graft hydrophobic groups on the surface of starch, resulting in unsatisfactory emulsification performance. In this work, a lipase-inorganic hybrid catalytic system with multi-scale flower like structure is designed and applied to spatially selective catalytic preparation of ocenyl succinic anhydride modified starch. With the appropriate floral morphology and petal density, lipases distributed in the "flower center" can selectively catalyze the grafting of hydrophobic groups in a spatial manner, the hydrophobic groups are concentrated on one side of starch particles. The obtaining OSA starch exhibits excellent emulsifying property, and the pickering emulsion has good protective effect on the embedded curcumin. This work provides a direction for the development of high-performance starch-based emulsifiers for the food and pharmaceutical industries, which is of great significance for improving the preparation and emulsification theory research of modified starch.

Amylopectin chain length distributions and amylose content are determinants of viscoelasticity and digestibility differences in mung bean starch and proso millet starch

This study aimed to reveal the underlying mechanisms of the differences in viscoelasticity and digestibility between mung bean starch (MBS) and proso millet starch (PMS) from the viewpoint of starch fine molecular structure. The contents of amylopectin B2 chains (14.94-15.09 %), amylopectin B3 chains (14.48-15.07 %) and amylose long chains (183.55-198.84) in MBS were significantly higher than PMS (10.45-10.76 %, 12.48-14.07 % and 70.59-88.03, respectively). MBS with higher amylose content (AC, 28.45-31.80 %) not only exhibited a lower weight-average molar mass (91,750.65-128,120.44 kDa) and R1047/1022 (1.1520-1.1904), but also was significantly lower than PMS in relative crystallinity (15.22-23.18 %, p < 0.05). MBS displayed a higher storage modulus (G') and loss modulus (G'') than PMS. Although only MBS-1 showed two distinct and discontinuous phases, MBS exhibited a higher resistant starch (RS) content than PMS (31.63-39.23 %), with MBS-3 having the highest RS content (56.15 %). Correlation analysis suggested that the amylopectin chain length distributions and AC played an important role in affecting the crystal structure, viscoelastic properties and in vitro starch digestibility of MBS and PMS. These results will provide a theoretical and scientific basis for the development of starch science and industrial production of low glycemic index starchy food.

The effect of lactic acid bacteria fermentation on physicochemical properties of starch from fermented proso millet flour

A waxy and a non-waxy proso millet flour were each fermented by Lactobacillus amylovorus, Lactobacillus fermentum, and Lactobacillus plantarum. The samples were fermented for one to five days, and starch was isolated from the fermented flours. The pH of fermented proso millet flour ranged from 3.27 to 3.6. The starch morphology of fermented samples differed from that of raw starches, with surface indentations and small pores leading to granule channels observed on the granule. The gelatinization temperatures were significantly decreased, whereas the enthalpies were not affected by fermentation. Peak and final viscosities were decreased after fermentation. The hardness of Lb. fermentum and Lb. plantarum fermented waxy starch gels was decreased, but the non-waxy samples fermented by Lb. amylovorus had significantly increased hardness. The adhesiveness of the starch gels from fermented samples was significantly increased. Lactic acid fermentation had significant effects on the morphology and physicochemical properties of proso millet starch.

Application and functional properties of millet starch: Wet milling extraction process and different modification approaches

In the past decade, the demand and interest of consumers have expanded for using plant-based novel starch sources in different food and non-food processing. Therefore, millet-based value-added functional foods are acquired spare attention due to their excellent nutritional, medicinal, and therapeutic properties. Millet is mainly composed of starch (amylose and amylopectin), which is primary component of the millet grain and defines the quality of millet-based food products. Millet contains approximately 70 % starch of the total grain, which can be used as a, ingredient, thickening agent, binding agent, and stabilizer commercially due to its functional attributes. The physical, chemical, and enzymatic methods are used to extract starch from millet and other cereals. Numerous ways, such as non-thermal physical processes, including ultrasonication, HPP (High pressure processing) high-pressure, PEF (Pulsed electric field), and irradiation are used for modification of millet starch and improve functional properties compared to native starch. In the present review, different databases such as Scopus, Google Scholar, Research Gate, Science Direct, Web of Science, and PubMed were used to collect research articles, review articles, book chapters, reports, etc., for detailed study about millet starch, their extraction (wet milling process) and modification methods such as physical, chemical, biological. The impact of different modification approaches on the techno-functional properties of millet starch and their applications in different sectors have also been reviewed. The data and information created and aggregated in this study will give users the necessary knowledge to further utilize millet starch for value addition and new product development.

Comparison of the fine structure and physicochemical properties of proso millet (Panicum miliaceum L.) starch from different ecological regions

Field experiments were conducted to evaluate the morphology, granule size, fine structure, thermal properties, and pasting properties of starch from a waxy (139) and a non-waxy (297) varieties of proso millet grown in Yulin (YY) and Yangling (YL). Compared with the starches from the two varieties grown in YY, the starches from the two varieties grown in YL exhibited higher relative crystallinities, 1045/1022 cm-1 ratio, and amounts of amylopectin long branch chains (APL) but lower 1022/995 cm -1 ratio, amounts of amylopectin short branch chains (APs), and APs/APL ratios. Starches from YL also synthesized long branch-chain amylopectin to enhance intermolecular interactions and form a stable granular structure, which resulted in increased starch gelatinization temperature, enhanced shear resistance, and reduced setback viscosity. Starch from the waxy (139) variety has good application prospects in the food industry because of its high gelatinization temperature and light transmittance and low setback value, which can be ascribed to its extremely low amylose content, polydispersity index, high molecular weight, and dispersed molecular density. It may serve as a reference for applying proso millet starches in the food industry and developing breeding programs to improve starch quality.

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.

Biochar and Nitrogen Fertilizer Change the Quality of Waxy and Non-Waxy Broomcorn Millet (Panicum miliaceum L.) Starch

The overuse of nitrogen fertilizers has led to environmental pollution, which has prompted the widespread adoption of biochar as a soil conditioner in agricultural production. To date, there has been a lack of research on the effects of biochar and its combination with nitrogen fertilizer on the quality of broomcorn millet (Panicum miliaceum L.) starch. Thus, this study examined the physicochemical characteristics of starch in two types of broomcorn millet (waxy and non-waxy) under four different conditions, including a control group (N0), nitrogen fertilizer treatment alone (N150), biochar treatment alone (N0+B), and a combination of biochar and nitrogen fertilizer treatments (N150+B). The results showed that, in comparison to the control, all the treatments, particularly N150+B, decreased the content of amylose and gelatinization temperature and enhanced the starch transparency gel consistency and swelling power. In addition, biochar can improve the water solubility of starch and the gelatinization enthalpy. Importantly, the combination of biochar and nitrogen fertilizer increased the proportion of A-granules, final viscosity, starch content, and the average degree of amylopectin in polymerization. Thus, this research indicates that the combinations of biochar and nitrogen fertilizer result in the most significant improvement in the quality of starch produced from broomcorn millet.

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.

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.

Understanding the multi-scale structure and physicochemical properties of millet starch with varied amylose content

The multi-scale structure and physicochemical properties of starch from five indigenous millet varieties were investigated and their correlations were revealed. Results showed that apparent amylose content (AAC) ranged from 12.3% to 27.4%, and as the amylose increasing, the ordered degree of starch double-helical, ordered molecular structure and crystalline structures displayed a declined trend. All millet starches showed polygonal, spherical or irregular shapes varied with size, but XIN-3 starch granules (highest AAC) presented higher granule rigidity, compactness and bulk intensity. Specifically, the ordered molecular structure (e.g., higher double-helix content, short-range ordered degree and relative crystallinity) of millet starch with low amylose limited the swelling degree of starch granules and in turn decreased the characteristic viscosity. However, rapidly digestible starch (RDS) was significantly negatively correlated with AAC and ordered molecular structure. The information obtained in this study would be significant in the rational utilization of these millet starches in food industry fields.

Millet seed oil activates β-catenin signaling and promotes hair growth

Alopecia, regardless of gender, exacerbates psychological stress in those affected. The rising prevalence of alopecia has fueled a research interest in preventing hair loss. This study investigates the potential of millet seed oil (MSO) in promoting the proliferation of hair follicle dermal papilla cells (HFDPC) and stimulating hair growth in animals with testosterone-dependent hair growth inhibition as part of a study on dietary treatments to improve hair growth. MSO-treated HFDPC significantly increased cell proliferation and phosphorylation of AKT, S6K1, and GSK3β proteins. This induces β-catenin, a downstream transcription factor, to translocate to the nucleus and increase the expression of factors related to cell growth. In a C57BL/6 mice model in which hair growth was inhibited by subcutaneous testosterone injection after shaving the dorsal skin, oral administration of MSO stimulated hair growth in the subject mice by increasing the size and number of hair follicles. These results suggest that MSO is a potent agent that may help prevent or treat androgenetic alopecia by promoting hair growth.

Analysis of Starch Structure and Pasting Characteristics of Millet Thick Wine during Fermentation

Starch is the main substrate in millet thick wine (MTW). In order to control the fermentation process of MTW, it is critical to monitor changes in the starch structure and physicochemical characteristics during the fermentation of MTW. In the present study, the structural characteristics of MTW starch were analyzed by scanning electron microscopy (SEM), confocal laser scanning microscopy (CLSM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and rapid viscosity analysis (RVA). The results of SEM and CLSM showed that large starch granules in MTW swelled, developed cavities, and ruptured or even vanished with the prolongation of the fermentation time, whereas the size and shape of small starch granules barely changed, only falling off the pomegranate-seed-like aggregates. With the increase in fermentation time, the relative crystallinity of starch in MTW gradually increased. In addition, the short-range ordered structures underwent complex changes. Changes in the starch morphology and ordered structure led to an increase in the peak viscosity time and the initial gelatinization temperature. The present results reveal the beneficial effect of fermentation on MTW processing and suggest its potential applications in other millet-based fermented products.

Transcriptome analysis reveals new insights in the starch biosynthesis of non-waxy and waxy broomcorn millet (Panicum miliaceum L.)

Broomcorn millet is a popular cereal with health benefits, and its grains are rich in starch. However, the differences in the pathway and key genes involved in starch biosynthesis of waxy and non-waxy broomcorn millet grain remain unclear. Therefore, the grain and starch physicochemical index and transcriptomic analyses of two genotypes of broomcorn millet were conducted at 3, 6, 9, 12, 15, 18, and 21 days after pollination. The phenotypic and physiological results indicated that the starch synthetic process of non-waxy and waxy broomcorn millet was significantly different. The amylose, amylopectin, and total starch contents of non-waxy broomcorn millet were 1.99, 4.74, and 6.73 mg/grain, while those of waxy broomcorn millet were 0.34, 5.94, and 6.28 mg/grain, respectively. The transcriptomic analysis revealed that 106 differentially expressed genes were identified, which were mainly enriched in the "amino sugar and nucleotide sugar metabolism", "pyruvate metabolism", "galactose metabolism", and "starch and sucrose metabolism" pathways. The WGCNA suggested that a total of 31 hub genes were correlated with starch biosynthesis. These findings provide a new approach to studying the starch synthesis in broomcorn millet.

Effect of Single and Dual Modifications on Properties of Lotus Rhizome Starch Modified by Microwave and γ-Irradiation: A Comparative Study

A comparative study between two novel starch modification technologies, i.e., microwave (MI) and γ-irradiation (IR), is of important significance for their applications. The objective of this work is to compare the changes in lotus rhizome starch (LRS) subjected to single modifications by MI (thermal treatment) and IR (non-thermal treatment), and dual modification by changing the treatment sequence, i.e., microwave followed by irradiation (MI-IR) and irradiation followed by microwave (IR-MI). The amylose content of native and modified LRS varied from 14.68 to 18.94%, the highest and lowest values found for native and MI-LRS, respectively. IR-treated LRS showed the lowest swelling power (4.13 g/g) but highest solubility (86.9%) among native and modified LRS. An increase in light transmittance value suggested a lower retrogradation rate for dual-modified starches, making them more suitable for food application at refrigeration and frozen temperatures. Dual-modified LRS showed the development of fissures and dents on the surface of granules as well as the reduction in peak intensities of OH and CH2 groups in FTIR spectra. Combined modifications (MI and IR) reduced values of pasting parameters and gelatinization properties compared to native and microwaved LRS and showed improved stability to shear thinning during cooking and thermal processing. The sequence of modification also affected the rheological properties; the G′ and G″ of MI-IR LRS were lower (357.41 Pa and 50.16 Pa, respectively) than the IR-MI sample (511.96 Pa and 70.09 Pa, respectively), giving it a soft gel texture. Nevertheless, dual modification of LRS by combining MI and IR made more significant changes in starch characteristics than single modifications.