Interactome of millet-based food matrices: A review

New insights into starch, lipid, and protein interactions - Colon microbiota fermentation

Starch, lipids, and proteins are essential biological macromolecules that play a crucial role in providing energy and nutrition to our bodies. Interactions between these macromolecules have been shown to impact starch digestibility. Understanding and controlling starch digestibility is a key area of research. Investigating the mechanisms behind the interactions of these three components and their influence on starch digestibility is of significant practical importance. Moreover, these interactions can result in the formation of resistant starch, which can be fermented by gut microbiota in the colon, leading to various health benefits. While current research has predominantly focused on the digestive properties of starch in the small intestine, there is a notable gap in understanding the colonic microbial fermentation phase of resistant starch. The benefits of fermentation of resistant starch in the colon may outweigh its glucose-lowering effect in the small intestine. Thus, it is crucial to study the fermentation behavior of resistant starch in the colon. This paper investigates the impact of interactions among starch, lipids, and proteins on starch digestion, with a specific focus on the fermentation phase of indigestible carbohydrates in the colon. Furthermore, valuable insights are offered for guiding future research endeavors.

A review of endogenous non-starch components in cereal matrix: spatial distribution and mechanisms for inhibiting starch digestion

As compared with exogenous components, non-starch components (NSCS), such as proteins, lipids, non-starch polysaccharides (NSPs), and polyphenols, inherently present in cereals, are more effective at inhibiting starch digestibility. Existing research has mostly focused on complex systems but overlooked the analysis of the in-situ role of the NSCS. This study reviews the crucial mechanisms by which endogenous NSCS inhibit starch digestion, emphasizing the spatial distribution-function relationship. Starch granules are filled with pores/channels-associated proteins and lipids, embedding in the protein matrix, and maintained by endosperm cell walls. The potential starch digestion inhibition of endogenous NSCS is achieved by altering starch gelatinization, molecular structure, digestive enzyme activity, and accessibility. Starch gelatinization is constrained by endogenous NSCS, particularly cell wall NSPs and matrix proteins. The stability of the starch crystal structure is enhanced by the proteins and lipids distributed in the starch granule pores and channels. Endogenous polyphenols greatly inhibit digestive enzymes and participate in the cross-linking of NSPs in the cell wall space, which together constitute a physical barrier that hinders amylase diffusion. Additionally, the spatial entanglement of NSCS and starch under heat and non-heat processing conditions reduces starch accessibility. This review provides novel evidence for the health benefits of whole cereals.

Advances in the novel and green-assisted techniques for extraction of bioactive compounds from millets: A comprehensive review

Millets are rich in nutritional and bioactive compounds, including polyphenols and flavonoids, and have the potential to combat malnutrition and various diseases. However, extracting these bioactive compounds can be challenging, as conventional methods are energy-intensive and can lead to thermal degradation. Green-assisted techniques have emerged as promising methods for sustainable and efficient extraction. This review explores recent trends in employing green-assisted techniques for extracting bioactive compounds from millets, and potential applications in the food and pharmaceutical industries. The objective is to evaluate and comprehend the parameters involved in different extraction methods, including energy efficiency, extraction yield, and the preservation of compound quality. The potential synergies achieved by integrating multiple extraction methods, and optimizing extraction efficiency for millet applications are also discussed. Among several, Ultrasound and Microwave-assisted extraction stand out for their rapidity, although there is a need for further research in the context of minor millets. Enzyme-assisted extraction, with its low energy input and ability to handle complex matrices, holds significant potential. Pulsed electric field-assisted extraction, despite being a non-thermal approach, requires further optimization for millet-specific applications, are few highlights. The review emphasizes the importance of considering specific compound characteristics, extraction efficiency, purity requirements, and operational costs when selecting an ideal technique. Ongoing research aims to optimize novel extraction processes for millets and their byproducts, offering promising applications in the development of millet-based nutraceutical food products. Therefore, the current study benefits researchers and industries to advance extraction research and develop efficient, sustainable, and scalable techniques to extract bioactive compounds from millets.

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.

Effect of non-starch components on the structural properties, physicochemical properties and in vitro digestibility of waxy highland barley starch

Highland barley (HB) endosperm with an amylose content of 0-10 % is called waxy HB (WHB). WHB is a naturally slow-digesting grain, and the interaction between its endogenous non-starch composition and the WHB starch (WHBS) has an important effect on starch digestion. This paper focuses on the mechanisms by which the components of β-glucan, proteins and lipids affect the molecular, granular, crystalline structure and digestive properties of WHBS. After eliminating the main nutrients except for starch, the estimated glycemic index (eGI) of the samples rose from 62.56 % to 92.93 %, and the rapidly digested starch content increased from 60.81 % to 98.56 %, respectively. The resistant starch (RS) content, in contrast, dropped from 38.61 % to 0.13 %. Comparatively to lipids, β-glucan and protein contributed more to the rise in eGI and decline in RS content. The crystalline characteristics of starch were enhanced in the decomposed samples. The samples' gelatinization properties improved, as did the order of the starch molecules. Protein and β-glucan form a dense matrix on the surface of WHBS particles to inhibit WHBS digestion. In summary, this study revealed the mechanism influencing the digestibility of WHBS from the perspective of endogenous non-starch composition and provided a theoretical basis to develop slow-digesting foods.

Effect of malting on physicochemical, antioxidant, and microstructural properties of finger millet (Eleusine coracana) flours

Finger millet (Eleusine coracana L. Gaertn.) is a gluten-free crop with a high amount of fiber, calcium and iron, outstanding malting qualities and a low glycemic index. The study aimed to determine the physicochemical, functional, antioxidant and microstructural properties of malted finger millet (light and dark brown) flours. The two varieties of finger millet grains were germinated for 0, 24, 48 and 72 h and kilned for 8 h. The lightness (L*) values of malted finger millet flours significantly increased, with light brown having the highest L* value of 76.62. The hue angle and total color differences (ΔE) of the malted finger millet flours increased significantly (p ≤ .05.), and values ranged from 63.43° to 71.20° (light brown) and 2.12° to 4.32° (dark brown), respectively. The moisture, ash, fiber, protein, total phenolic, total flavonoids contents and DPPH activity of both malted finger millet flours significantly increased. On the contrary, the fat, carbohydrate, energy contents and FRAP activity significantly decreased with each malting period of both finger millet flours. Both malted finger millet flours' solubility index, water and oil absorption capacity increased significantly while the packed and loose bulk density decreased. Malting had no significant effect on the viscosity of the cold paste; however, a significant decrease in the viscosity of the cooked paste in both finger millet flours was observed, with values ranging from 285 to 424.00 cP (light brown) and 271.33 to 418.00 cP (dark brown), respectively. Malting resulted in changes in the thermal properties of finger millet flours with an increase in the onset, peak and conclusion temperatures. Fourier-Transform Infrared Spectra showed that malting slightly changed the peaks of both finger millet flours. Scanning electron microscopy showed that malting altered the microstructural characteristics of finger millet flours. The results showed that malted finger millet flours are promising raw materials for gluten-free bakery products.

Enhanced Elderberry Snack Bars: A Sensory, Nutritional, and Rheological Evaluation

Interest in functional foods is continuously increasing, having the potential to be an ally in reducing cardiometabolic risk factors. This study focuses on developing and evaluating oat- and millet-based snack bars enriched with freeze-dried elderberry powder (FDEBP), aiming to combine great taste with enhanced nutritional value, antioxidant properties, and prebiotic potential. The research encompassed a sensory evaluation, nutritional assessment, and rheological analysis of the snack bars. A hedonic test was conducted to gauge consumer preferences and overall liking, providing insights into taste, texture, and acceptance. Sensory evaluation revealed positive feedback from participants, and acceptance rating scores ranged from 7 to 8.04, the best score recorded by one of the enhanced bars with 1% FDEBP. The rheological analysis determined the bars' dynamic storage modulus (G') and loss modulus (G″), assessing the material's elasticity and mechanical properties. Results showed that the incorporation of 0.5% and 1% FDEBP in the oat and millet snack bars significantly impacted their rheological properties, enhancing structural strength. Nutritional analysis demonstrated that the snack bars provided a complete mix of macronutrients required in a daily diet. The study sheds light on the potential of functional snack bars enriched with FDEBP, offering a delectable way to access essential nutrients and bioactive compounds in a minimally processed form, without the addition of sweeteners or additives, friendly to the gut microbiota.

Uncovering the differences in flavor volatiles of different colored foxtail millets based on gas chromatography-ion migration spectrometry and chemometrics

The differences of volatile organic compounds in commercially available foxtail millets with different colors (black, green, white and yellow) were assayed through gas chromatography-ion migration spectrometry (GC-IMS) to explore their volatile flavor characteristics. Fifty-five volatile components were found in various colored foxtail millets, including 25 kinds of aldehydes (accounting for 39.19-48.69%), 10 ketones (25.36-32.37%), 15 alcohols (20.19-24.11%), 2 ethers (2.29-2.45%), 2 furans (1.49-2.95%) and 1 ester (0.27-0.39%). Aldehydes, alcohols and ketones were the chief volatiles in different colored foxtail millet, followed by furans, esters and ethers. These identified volatile flavor components in various colored foxtail millets obtained by GC-IMS could be well distinguished by principal components and cluster analysis. Meanwhile, a stable prediction model was fitted via partial least squares-discriminant analysis (PLS-DA), in which 17 kinds of differentially volatile components were screened out based on variable importance in projection (VIP>1). These findings might provide certain information for understanding the flavor traits of colored foxtail millets in future.

Characterization and discrimination of flavor volatiles of different colored wheat grains after cooking based on GC-IMS and chemometrics

Changes in flavor volatiles of three colored wheat grains (black, green, and yellow) after cooking were detected via gas chromatography-ion migration spectrometry (GC-IMS) to explore corresponding volatile flavor traits. A total of 52 volatile chemicals were spotted among these cooked wheat grains, including 30 aldehydes (accounting for 73.86-83.78%), 11 ketones (9.53-16.98%), 3 alcohols (0.88-1.21%), 4 furans (4.82-7.44%), 2 esters (0.28-0.42%), and 2 pyrazines (0.18-0.32%). Aldehydes, ketones, and furans were the main volatile compounds in three different cooked wheat. For black-colored wheat, the relative contents of benzene acetaldehyde, benzaldehyde, 2-methyl butanal, and 3-methyl butanal were much higher (p < 0.05). For green-colored wheat, the relative contents of nonanal, 2-pentyl furan, (E)-hept-2-enal, 2-butanone, and acetone were significantly higher (p < 0.05). For yellow-colored wheat, the relative amounts of heptanal, hexanal, and pentanal were much higher (p < 0.05). The overall volatile substances of the three cooked wheat grains might be classified by GC-IMS data coupled with principal component analysis and heatmap clustering analysis. A reliable forecast set was established through orthogonal partial least squares-discriminant analysis (OPLS-DA), and 22 differential volatile compounds were screened out based on variable importance in projection (VIP) being higher than 1.0, as flavor markers for distinguishing the three cooked wheat grains. These results suggest that GC-IMS could be used for characterizing the flavor volatiles of different colored wheat, and the findings could contribute certain information for understand the aroma traits in different colored cooked wheat and related products in the future.

Anthocyanin and proanthocyanidin from Aronia melanocarpa (Michx.) Ell.: Purification, fractionation, and enzyme inhibition

Aronia melanocarpa (Michx.) Ell. is a rich source of anthocyanins and proanthocyanidins with confirmed health benefits. Individual cyanidin glucosides (cyanidin 3-galactoside, cyanidin 3-arabinoside, cyanidin 3-xyloside, and cyanidin 3-glucoside) of anthocyanins (calculated by individual cyanin glycoside fractions was 419.9 mg/100 g FW) were isolated by Sephadex LH-20 column and different parts of proanthocyanidins with a different mean degree of polymerization (mDP) were fractionated by the solubility differences in different solvents. The composition of different mDP of proanthocyanidins was as follows: monomers (1.51%), oligomer (mDP of 4.2 ± 0.9, 20.57%), CPP-50 (mDP of 78.9 ± 4.1, 22.17%), CPP-60 (mDP of 66.1 ± 1.2, 27.94%), CPP-70 (mDP of 36.8 ± 3.9, 36.8%), CPP-75 (mDP of 25.2 ± 1.3, 6.14%), CPP-L (mDP of 10.2 ± 2.6, 6.95%), and there were recycling loss of 0.34%. Cyanidin 3-glucoside showed the strongest inhibition effects on α-amylase and lipase and cyanidin 3-arabinoside showed the strongest inhibition effect on α-glucosidase, while cyanidin 3-xyloside has no inhibition effect on the α-amylase, and cyanidin 3-galactoside, cyanidin 3-arabinoside, and cyanidin 3-xyloside have no inhibition effects on lipase. The inhibition effect of proanthocyanidins with different mDP to the enzymes all showed high negative correlations between the mDP and IC₅₀ (half-maximal inhibitory concentration). This study suggests that A. melanocarpa (Michx.) Ell. can have beneficial effects due to inhibition of the digestion enzyme.