Storage stability, micronisation, and application of nutrient-dense fraction of proso millet bran in gluten-free bread

Hydrothermal extraction of dietary fiber from pearl millet bran: optimization, physico-chemical, structural and functional characterization

Pearl millet bran is rich source of dietary fiber and several other bioactive compounds and is an unexploited by-product of millet processing industries. The utilization of pearl millet bran for extraction of dietary fiber can be an effective method for its valorization. Hydrothermal extraction of dietary fiber from pearl millet bran is a simple eco-friendly technique in terms of minimal consumption of toxic solvents, increased extraction yield, high purity and considered as an economically viable technique. In the present investigation, extraction and optimization of dietary fiber from pearl millet bran was performed using hydrothermal technique. The highest yield of dietary fiber (74.5%, w/w) was obtained under optimized conditions of water to solid ratio (20:1), temperature (90 °C) and time (15 min). The extracted dietary fiber from pearl millet bran was further assessed for its physico-chemical, functional and structural properties. The studies of functional and physico-chemical properties presented the water holding capacity (6.50 g/g and 3.99 g/g), swelling power (2.0 g/g and 2.05 g/g), oil holding capacity (4.91 g/g and 2.42 g/g), solubility (70%), total phenolic content of 4.24 mg GAE/g and 4.32 mg GAE/g, DPPH reduction of 86.6% and 83.9%, respectively. The results indicated that pearl millet bran can act as rich source of dietary fiber with health enhancing properties and can be utilized as potential food component in preparation of functional food products.

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.

Review on Nutritional Potential of Underutilized Millets as a Miracle Grain

The current situation, which includes changes in eating habits, an increasing population, and the unrestricted use of natural resources, has resulted in a lack of resources that could be used to provide nourishing food to everyone. Natural plant resources are quickly being depleted, so it is necessary to consider new alternatives. In addition to the staple grains of rice and wheat, many other crops are being consumed that need to be utilized to their full potential and have the potential to replace the staple crops. Millets are one of the most important underutilized crops that have the potential to be used as a nutricereal. Millets have a high nutritional value, do not produce acids, do not contain gluten, and can contribute to a healthy diet. Due to a lack of awareness regarding the nutritional value of millets, their consumption is still restricted to the population that adheres to conventional diets and is economically disadvantaged even though millets contain a significant amount of nutrients. Millets are becoming increasingly unpopular due to a lack of processing technologies, food subsidies, and the inconvenience of preparing food with millets. Millets are a Nutricereal rich in carbohydrates, dietary fibers, energy, essential fatty acids, proteins, vitamin B, and minerals such as calcium, iron, magnesium, potassium, and zinc. These nutrients help to protect against post-translational diseases such as diabetes, cancer, cardiovascular disease, and celiac disease, among others. Millets are beneficial for controlling blood pressure, blood sugar level, and thyroid function; however, despite these functional properties, millets consumption has declined. Utilizing millets and other staple food crops to develop alternative food sources has become a new area of focus for businesses in the food industry. In addition, millet consumption can help foster immunity and health, which is essential in strengthening our fight against malnutrition in children and adolescents. In this article, the authors examine the potential of millets in terms of their nutricereal qualities.

Potential Effects of the Different Matrices to Enhance the Polyphenolic Content and Antioxidant Activity in Gluten-Free Bread

Gluten-related disorders, including celiac disease, wheat allergy, and non-celiac gluten sensitivity, have emerged as a significant phenomenon affecting people worldwide, with an estimated prevalence of nearly 5% globally. The only currently available treatment for this disease involves the exclusion of gluten from the diet, which is particularly challenging in the case of bakery products. Gluten-free bread (GFB) presents certain disadvantages when compared to traditional wheat bread, including inferior sensory attributes, technological characteristics, and lower protein and fiber content. Numerous studies have focused on strategies to improve these aspects of GFB. However, there are limited reviews regarding the content of the bioactive compounds of GFB, such as polyphenols. Polyphenols are molecules found in various foods that play a vital role in protecting the body against oxidative stress. This is particularly relevant for individuals with gluten intolerance or celiac disease, as they often experience increased oxidative stress and inflammation. Therefore, the objective of this review is to explore the use of different strategies for increasing the polyphenolic content and the antioxidant properties of GFB. Gluten-free cereals and pseudocereals are the most used matrices in GFB. Buckwheat can be a valuable matrix to enhance the nutritional profile and antioxidant properties of GFB, even more so when the whole grain is used. In the same way, the addition of various by-products can effectively increase the bioactive compounds and antioxidant activity of GFB. Furthermore, regarding the contribution of the phenolics to the bitterness, astringency, color, flavor, and odor of food, it is essential to analyze the sensory properties of these breads to ensure not only enriched in bioactive compounds, but also good consumer acceptance. In vitro studies are still in few number and are very important to execute to provide a better understanding of the bioactive compounds after their consumption.

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.

Influence of Particle Size and Xylanase Pretreatment of Proso Millet Bran on Physical, Sensory and Nutritive Features of Gluten-Free Bread

Research background

Millet bran is a by-product rich in dietary fibre, micronutrients and bioactive compounds which are often deficient in a gluten-free diet. Previously, cryogenic grinding has been shown to improve the functionality of bran to some extent, although it offered limited benefits for bread making. This study aims to investigate the effects of adding proso millet bran depending on its particle size and xylanase pretreatment on the physicochemical, sensory and nutritional properties of gluten-free pan bread.

Experimental approach

Coarse bran (d50=223 μm) was ground to medium size (d50=157 μm) using an ultracentrifugal mill or to superfine particles (d50=8 μm) using a cryomill. Millet bran presoaked in water (for 16 h at 55 °C) with or without the addition of fungal xylanase (10 U/g) replaced 10% of the rice flour in the control bread. Bread specific volume, crumb texture, colour and viscosity were measured instrumentally. Along with proximate composition, the content of soluble and insoluble fibre, total phenolic compounds (TPC) and phenolic acids as well as total and bioaccessible minerals of bread were assessed. Sensory analysis of the bread samples included a descriptive, hedonic and ranking test.

Results and conclusions

Dietary fibre content (7.3-8.6 g/100 g) and TPC (42-57 mg/100 g) on dry mass basis of the bread loaves depended on bran particle size and xylanase pretreatment. The effect of xylanase pretreatment was most evident in the loaves with medium bran size in terms of higher content of fibre soluble in ethanol (45%) and free ferulic acid content (5%), improved bread volume (6%), crumb softness (16%) and elasticity (7%), but lower chewiness (15%) and viscosity (20-32%). Bread bitterness and dark colour were increased after adding medium-sized bran but its bitter aftertaste, crust crookedness, crumb hardness and graininess were reduced with xylanase pretreatment. Although bran addition impaired protein digestibility, it enriched the bread with iron (341%), magnesium (74%), copper (56%) and zinc (7.5%). Xylanase pretreatment of the bran resulted in the improved bioaccessibility of zinc and copper of the enriched bread compared to the control and bread without xylanase.

Novelty and scientific contribution

Application of xylanase to medium sized bran obtained by ultracentrifugal grinding was more successful than its application to superfine bran obtained by the multistage cryogrinding as it resulted in more soluble fibre in gluten-free bread. Moreover, xylanase was proven beneficial in maintaining desirable bread sensory properties and mineral bioaccessibility.

The Influence of Cryogrinding on Essential Oil, Phenolic Compounds and Pigments Extraction from Myrtle (Myrtus communis L.) Leaves

The aim of this study was to investigate the influence of cryogrinding pretreatment on the recovery of essential oil, phenolics and pigments from myrtle leaves. The duration of cryogrinding (3, 6 and 9 min) in combination with the duration of hydrodistillation (30, 60 and 90 min) for the isolation of essential oils and the duration of hydroethanolic extraction (5, 10 and 15 min) for the isolation of phenols and pigments were studied as independent factors in a full factorial design. The major volatile components detected in myrtle leaf essential oil were myrtenyl acetate, 1,8-cineole, α-pinene and linalool. The most abundant phenols detected were myricetin derivatives (myricetin 3-O-galactoside and myricetin 3-O-rhamnoside), galloylquinic acid, myricetin and digalloylquinic acid, while the major pigments were chlorophyll b, pheophytin a and lutein. A 3 min cryogrinding pretreatment significantly increased the yield and concentrations of essential oil volatile compounds and reduced the distillation time to 30 min. A 9 min cryogrinding pretreatment and 15 min extraction resulted in at least 40% higher concentrations of phenolic compounds and pigments in the extracts when compared to the untreated control. According to the results obtained, cryogrinding can significantly increase the yield of myrtle EO and extracts and also modulate their composition.

Antidiabetic Effect of Millet Bran Polysaccharides Partially Mediated via Changes in Gut Microbiome

Diabetes is a type of metabolic disease associated with changes in the intestinal flora. In this study, the regulatory effect of millet bran on intestinal microbiota in a model of type 2 diabetes (T2DM) was investigated in an effort to develop new approaches to prevent and treat diabetes and its complications in patients. The effect of purified millet bran polysaccharide (MBP) with three different intragastric doses (400 mg/kg, 200 mg/kg, and 100 mg/kg) combined with a high-fat diet was determined in a streptozotocin (STZ)-induced model of T2DM. By analyzing the changes in indicators, weight, fasting blood sugar, and other bio-physiological parameters, the changes in gut microbiota were analyzed via high-throughput sequencing to establish the effect of MBP on the intestinal flora. The results showed that MBP alleviated symptoms of high-fat diet-induced T2DM. A high dosage of MBP enhanced the hypoglycemic effects compared with low and medium dosages. During gavage, the fasting blood glucose (FBG) levels of rats in the MBP group were significantly reduced (p < 0.05). The glucose tolerance of rats in the MBP group was significantly improved (p < 0.05). In diabetic mice, MBP significantly increased the activities of CAT, SOD, and GSH-Px. The inflammatory symptoms of liver cells and islet cells in the MBP group were alleviated, and the anti-inflammatory effect was partially correlated with the dose of MBP. After 4 weeks of treatment with MBP, the indices of blood lipid in the MBP group were significantly improved compared with those of the DM group (p < 0.05). Treatment with MBP (400 mg/kg) increases the levels of beneficial bacteria and decreases harmful bacteria in the intestinal tract of rats, thus altering the intestinal microbial community and antidiabetic effect on mice with T2DM by modulating gut microbiota. The findings suggest that MBP is a potential pharmaceutical supplement for preventing and treating diabetes.

Effect of Mechanical Grinding on the Physicochemical, Structural, and Functional Properties of Foxtail Millet (Setaria italica (L.) P. Beauv) Bran Powder

This study investigated the functional, physicochemical, and structural characteristics of foxtail millet bran powder with different particle sizes. The morphological analysis revealed that the surface roughness declined in conjunction with the particle sizes of the millet bran powder. The Fourier-transform infrared (FTIR) spectra showed that none of the samples generated any additional chemical functional groups. A decrease in the particle sizes of the millet bran powder increased their dissemination and surface areas, as well as the bulk density, tap density, water-holding capacity (WHC), angle of repose (θ) and angle of slide (α), and peak temperature, while the oil holding capacity (OHC) and crystallinity index (CI) value declined. Moreover, fine millet bran powder (54.7 μm) exhibited a higher protein, fat, soluble dietary fiber (SDF), total phenolic content, and antioxidant capacity than its coarse counterpart.

Delving into the Role of Dietary Fiber in Gluten-Free Bread Formulations: Integrating Fundamental Rheological, Technological, Sensory, and Nutritional Aspects

The evidenced relevance of dietary fibers (DF) as functional ingredients shifted the research focus towards their incorporation into gluten-free (GF) bread, aiming to attain the DF contents required for the manifestation of health benefits. Numerous studies addressing the inclusion of DF from diverse sources rendered useful information regarding the role of DF in GF batter’s rheological properties, as well as the end product’s technological and nutritional qualities. The presented comprehensive review aspires to provide insight into the changes in fiber-enriched GF batter’s fundamental rheological properties, and technological, sensory, and nutritional GF bread quality from the insoluble and soluble DF (IDF and SDF) perspective. Different mechanisms for understanding IDF and SDF action on GF batter and bread were discussed. In general, IDF and SDF can enhance, but also diminish, the properties of GF batter and bread, depending on their addition level and the presence of available water in the GF system. However, it was seen that SDF addition provides a more homogenous GF batter structure, leading to bread with higher volumes and softer crumb, compared to IDF. The sensory properties of fiber-enriched GF breads were acceptable in most cases when the inclusion level was up to 7 g/100 g, regardless of the fiber type, enabling the labeling of the bread as a source of fiber.

Food Processing Technologies to Develop Functional Foods With Enriched Bioactive Phenolic Compounds in Cereals

Cereal grains and products provide calories globally. The health benefits of cereals attributed to their diverse phenolic constituents have not been systematically explored. Post-harvest processing, such as drying, storing, and milling cereals, can alter the phenolic concentration and influence the antioxidant activity. Furthermore, cooking has been shown to degrade thermo-labile compounds. This review covers several methods for retaining and enhancing the phenolic content of cereals to develop functional foods. These include using bioprocesses such as germination, enzymatic, and fermentation treatments designed to enhance the phenolics in cereals. In addition, physical processes like extrusion, nixtamalization, and parboiling are discussed to improve the bioavailability of phenolics. Recent technologies utilizing ultrasound, micro- or nano-capsule polymers, and infrared utilizing processes are also evaluated for their effectiveness in improving the phenolics content and bio-accessibility. We also present contemporary products made from pigmented cereals that contain phenolics.

Improving the oxidative stability of breadsticks with ginkgo (Ginkgo biloba) and ginseng (Panax ginseng) dried extracts

Recently, there has been a growing interest in the use of natural antioxidants instead of synthetic ones. The aim of this work was to determine the effect of ginkgo and ginseng dried extracts as natural antioxidants on the stability of lipids in breadsticks over 55 days of storage at room temperature compared to butylated hydroxytoluene. Ginkgo and ginseng dried extracts were incorporated individually into breadstick formulae at levels of 0.5 and 1% to enhance its oxidative stability in storage. The increases in peroxide, p-anisidine and Totox values in the oil phase of the samples during storage were monitored. The changes in hydroperoxide, trans fatty acid and aldehyde contents were investigated by Fourier transform infrared spectroscopy. The sensory analysis was performed to evaluate the perceptible changes occurring during storage. The results indicated that the oxidation of oil in breadstick samples can be retarded by enriching the breadstick formula with dried ginseng extract at a 1% level.

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).

Substantiation of basic stages of gluten-free steamed bread production and its influence on quality of finished product

Development and introduction of high quality gluten-free products is one of the priorities of food industry. Feasibility of producing gluten-free steamed bread based on rice and corn flour using flaxseed, sunflower, sorghum and quinoa flour additives is proved in the article. Recommended ratios of flours are established: Frc:Ffs 95:5, Frc:Fsn 95:5, Fcn:Fqn 85:15, Fcn:Fsg 90:10. The parameters of dough kneading are studied and the influence of additives on relative elasticity, plasticity and resilience is established. Use of additives leads to a decrease in irreversible relative deformation of dough for 36 – 68% and relative plasticity for 16 – 18%, to increase of its elasticity relative resilience up to 2.3 times. Dough fermentation process is investigated. It is established that amount of carbon dioxide accumulated in gluten-free dough increases by 10 – 30%. Process of acid accumulation during fermentation is studied. A flow chart for the production of gluten-free steamed bread is proposed. The parameters for the production of gluten-free steamed bread were established and justified. Product is prepared in a single-phase method, adopted in practice of baking bread. The duration of dough mixing is 10 – 15 min, fermentation 20 – 35 min. Steam treatment is carried out under atmospheric pressure. Recommended steam processing time is 35 min for bread based on rice flour, 30 min for based on corn flour. In comparison with the traditional technological scheme, it is recommended to use a double boiler instead of an oven.