Increasing the utilisation of sorghum, millets and pseudocereals: Developments in the science of their phenolic phytochemicals, biofortification and protein functionality

Nutritional and functional perspectives of pseudocereals

An increase in the consumption of carbohydrate-rich cereals over past few decades has led to increased metabolic disorders in population. This nutritional imbalance in diets may be corrected by substituting cereal grains with pseudocereals that are richer in high-quality proteins, dietary fibers, unsaturated fats, and bioactive compounds (e.g., polyphenols and phytosterols) as compared to cereal grains. These nutrients have been associated with numerous health benefits, such as hypolipidemic, anti-inflammatory, anti-hypertensive, anti-cancer, and hepatoprotective properties, and benefits against obesity and diabetes. In this review, the nutritional composition and health benefits of quinoa, amaranth, and buckwheat are compared against wheat, maize, and rice. Subsequently, the processing treatments applied to quinoa, amaranth, and buckwheat and their applications into food products are discussed. This is relevant since there is substantial market potential for both pseudocereals and functional foods formulated with pseudocereals. Despite clear benefits, the current progress is slowed down by the fact that the cultivation of these pseudocereals is limited to its native regions. Therefore, to meet the global needs, it is imperative to support worldwide cultivation of these nutrient-rich pseudocereals.

Presence of the neurotoxin β-N-methylamino-L-alanine in irrigation water and accumulation in cereal grains with human exposure risk

The present study demonstrates the presence of the neurotoxin β-N-methylamino-L-alanine and its cyanobacterial producers in irrigation water and grains of some cereal plants from farmlands irrigated with Nile River water in Egypt. BMAA detected by LC-MS/MS in phytoplankton samples was found at higher concentrations of free form (0.84-11.4 μg L-1) than of protein-bound form (0.16-1.6 μg L-1), in association with the dominance of cyanobacteria in irrigation water canals. Dominant cyanobacterial species isolated from these irrigation waters including Aphanocapsa planctonica, Chroococcus minutus, Dolichospermum lemmermanni, Nostoc commune, and Oscillatoria tenuis were found to produce different concentrations of free (4.8-71.1 µg g-1 dry weight) and protein-bound (0.1-11.4 µg g-1 dry weight) BMAA. In the meantime, BMAA was also detected in a protein-bound form only in grains of corn (3.87-4.51 µg g-1 fresh weight) and sorghum (5.1-7.1 µg g-1 fresh weight) plants, but not in wheat grains. The amounts of BMAA accumulated in these grains correlated with BMAA concentrations detected in relevant irrigation water canals. The presence of BMAA in cereal grains would constitute a risk to human and animal health upon consumption of contaminated grains. The study, therefore, suggests continuous monitoring of BMAA and other cyanotoxins in irrigation waters and edible plants to protect the public against exposure to such potent toxins.

Effects of Red Sorghum-Derived Deoxyanthocyanidins and Their O-β-D-Glucosides on E-Cadherin Promoter Activity in PC-3 Prostate Cancer Cells

Although much less common than anthocyanins, 3-Deoxyanthocyanidins (3-DAs) and their glucosides can be found in cereals such as red sorghum. It is speculated that their bioavailability is higher than that of anthocyanins. Thus far, little is known regarding the therapeutic effects of 3-DAs and their O-β-D-glucosides on cancer, including prostate cancer. Thus, we evaluated their potential to decrease cell viability, to modulate the activity of transcription factors such as NFκB, CREB, and SOX, and to regulate the expression of the gene CDH1, encoding E-Cadherin. We found that 4',7-dihydroxyflavylium chloride (P7) and the natural apigeninidin can reduce cell viability, whereas 4',7-dihydroxyflavylium chloride (P7) and 4'-hydroxy-7-O-β-D-glucopyranosyloxyflavylium chloride (P3) increase the activities of NFkB, CREB, and SOX transcription factors, leading to the upregulation of CDH1 promoter activity in PC-3 prostate cancer cells. Thus, these compounds may contribute to the inhibition of the epithelial-to-mesenchymal transition in cancer cells and prevent the metastatic activity of more aggressive forms of androgen-resistant prostate cancer.

Development and characterization of physical stability, glycemic index, flow behaviors, and antioxidant activity of finger millet-based beverage

Millets are gaining attention as a superfood due to their higher nutritional value and cost-effectiveness. In this regard, extraction condition for the development of finger millet-based beverage was optimized using a central composite design. Soaking time (X1) and temperature (X2) in the range of 5-10 h and 40-60°C, respectively, were the independent variables taken for three responses, namely, yield, total solids, and sedimentation index. The optimized conditions are best fitted in quadratic model (R2 0.91) for all the dependent variables. Accordingly, the optimized levels selected for soaking time and temperature were 10 h and 60°C respectively, resulting in the yield (Y1) of 91.86% ± 0.94%, total solids (Y2) of 17.72% ± 0.56%, and sedimentation index (Y3) of 12.18% ± 0.06%. Further, xanthan gum (0.5%) and jaggery powder (5%) were added in the optimized beverage to improve its physicochemical and functional properties. Xanthan gum improved the physical stability and rheological properties of the beverage, whereas jaggery improved the flavor and phenolic content of the same. The optimized beverage had a good amount of phenolic content (53.70 µg GAE/mL), antioxidant activity (DPPH 13.76 µmol/mL), zeta potential (-19.8 mV), and glycemic index (57). The flow curve of beverages was obtained using power law model, and result indicated good consistency index (k = 0.7716 Pa s) with flow behavior (n = 0.3411) depicted its pseudoplastic nature. The optimized extraction condition significantly reduced the antinutrients, tannin, and phytic content by 47% and 14%, respectively, in optimized beverage than control.

Encapsulation of Sorghum Leaf Red Dye: Biological and Physicochemical Properties and Effect on Stability

The encapsulation of the 3-deoxyanthocyanidins (3-DXA) red dye, extracted from sorghum (Sorghum bicolor L.) leaves, was explored for food application. The extracts showed antioxidant activity at concentrations ranging from 803 to 1210 μg mL^-1 and did not reveal anti-inflammatory or cytotoxic properties, indicating their potential for food application. Encapsulation was performed with two carrier agents (maltodextrin and Arabic gum) in different proportions (1:1, 2:1 and 1.5:2.5 (w/w)). The microparticles produced by freeze-drying and spray-drying were studied according to the concentration of the dye, the encapsulation efficiency, the process yield, the solubility and the colour of the powders. The dye extracts are released from the microparticles at different pHs. The variation in ratio composition of the 3-DXA encapsulation was assessed by principal component analysis (PCA) using data from ten physicochemical parameters. The results indicated that the maltodextrin at the 2:1 ratio had a higher dye concentration and total phenolic content (TPC) at pH 6. This ratio was selected to produce the microparticles by freeze-drying and spray-drying, and the particles were used in the temperature stability tests at pH 6. The results suggest that the freeze-drying process offers better protection to 3-DXA, with a degradation percentage of 22% during the heating period (80 °C for 18 h), compared to the non-encapsulated dye (48%). However, there were no significant differences between the two polymeric agents. The non-encapsulated 3-DXA was evaluated as control and lost 48% of the total colour with the same treatment. Red dyes from sorghum leaf by-products may constitute promising ingredients for the food industry and increase the value of this crop.

A New Method to Determine Antioxidant Activities of Biofilms Using a pH Indicator (Resazurin) Model System

Biopolymeric films were prepared with gelatin, plasticizer, and three different types of antioxidants (ascorbic acid, phytic acid, and BHA) corresponding to different mechanisms in activity. The antioxidant activity of films was monitored for 14 storage days upon color changes using a pH indicator (resazurin). The instant antioxidant activity of films was measured by a DPPH free radical test. The system using resazurin was composed of an agar, an emulsifier, and soybean oil to simulate a highly oxidative oil-based food system (AES-R). Gelatin-based films (GBF) containing phytic acid showed higher tensile strength and energy to break than all other samples due to the increased intermolecular interactions between phytic acid and gelatin molecules. The oxygen barrier properties of GBF films containing ascorbic acid and phytic acid increased due to the increased polarity, while GBF films containing BHA showed increased oxygen permeability compared to the control. According to "a-value" (redness) of the AES-R system tested with films, films incorporating BHA showed the most retardation of lipid oxidation in the system. This retardation corresponds to 59.8% antioxidation activity at 14 days, compared with the control. Phytic acid-based films did not show antioxidant activity, whereas ascorbic acid-based GBFs accelerated the oxidation process due to its prooxidant activity. The comparison between the DPPH free radical test and the control showed that the ascorbic acid and BHA-based GBFs showed highly effective free radical scavenging behavior (71.7% and 41.7%, respectively). This novel method using a pH indicator system can potentially determine the antioxidation activity of biopolymer films and film-based samples in a food system.

Characterization of Sorghum Processed through Dry Heat Treatment and Milling

Sorghum grain nutritional quality can be enhanced by applying dry heat treatments. The purpose of this study was to investigate the effects of dry heat treatment at two temperatures (121 and 14 °C) with three fractionation factors (S fraction < 200 μm, M fraction 200–250 μm and, L fraction > 300 μm) on sorghum flour chemical and functional properties, to optimize processes by means of a desirability function, and to characterize the optimal products. Treatment temperature negatively affected oil- and water-absorption capacity, protein and moisture contents, while the opposite trend was obtained for hydration capacity, swelling power, emulsifying properties, fat, ash, and carbohydrate content. Sorghum flour fractions positively influenced the hydration and water-retention capacities, emulsifying properties, and protein and carbohydrate content, while oil absorption, swelling power, fat, ash, and moisture were negatively affected. The optimal processing determined for each fraction was heat treatment at 121.00 °C for S fraction, 132.11 °C for M, and 139.47 °C for L. Optimal product characterization revealed that the color, bioactive properties, and protein and starch structures of the optimal samples had changed after heat treatment, depending on the fraction. These findings could be helpful for the cereal industry, since sorghum flour could be an alternative for conventional crops for the development of new products, such as snacks, baked goods, and pasta.

A Review of the Potential Consequences of Pearl Millet (Pennisetum glaucum) for Diabetes Mellitus and Other Biomedical Applications

Diabetes mellitus has become a troublesome and increasingly widespread condition. Treatment strategies for diabetes prevention in high-risk as well as in affected individuals are largely attributed to improvements in lifestyle and dietary control. Therefore, it is important to understand the nutritional factors to be used in dietary intervention. A decreased risk of diabetes is associated with daily intake of millet-based foods. Pearl millet is a highly nutritious grain, nutritionally comparable and even superior in calories, protein, vitamins, and minerals to other large cereals, although its intake is confined to lower income segments of society. Pearl millet contains phenolic compounds which possess antidiabetic activity. Thus, it can be used to prepare a variety of food products for diabetes mellitus. Moreover, it also has many health benefits, including combating diabetes mellitus, cancer, cardiovascular conditions, decreasing tumour occurrence, lowering blood pressure, heart disease risk, cholesterol, and fat absorption rate. Therefore, the current review addresses the role of pearl millet in managing diabetes.

Variation in Phenolic, Mineral, Dietary Fiber, and Antioxidant Activity across Southern Tunisian Pearl Millet Germplasm

Pearl millet crop, reputed as one of the most important food sources cultivated in arid and semiarid parts of Africa and Asia, is known to be a source of many bioactive molecules with potential health-promoting properties. In Tunisia, this crop presented historically rich and diversified germplasm, which is being threatened by genetic erosion. The preservation programs of these species have been held for more than 20 years via participatory breeding schemes. A prospection was undertaken to collect pearl millet cultivars preserved in the last two decades from south-eastern Tunisian farmers to estimate their variability and performances. The aim of this study was to assess the profiles of phenolic compounds, antioxidant capacities, mineral composition, and dietary fiber contents of ten pearl millet cultivars in south-eastern Tunisia. The total phenolics and flavonoids in the free fraction ranged from 506.33 to 1287.71 µg.g−1 DM ferulic acid equivalent (FAE) and 4.17 to 12.53 µg.g−1 DM catechin equivalent (CE), respectively. The highest polyphenolic content from all genotypes was 1134.96 µg·g−1 DM (genotype Med.AG1.3). LC-MS analysis of individual phenol compounds allowed the identification of eight phenolic acids in millet grains. The quinic acid, p-coumaric acid, and caffeic acid were predominant phenolic acids, and six flavonoid compounds with cirsiliol and silymarin were the predominant flavonoids. The ranges of mineral contents variation were 693.10 to 1075.40 and 80.75 to 175.40 μg·g−1 for Ca and Mg, respectively, and 9.55 to 32.80, 0.75 to 8.60, 1.84 to 12.21, and 3.63 to 11.40 μg·g−1 for Na, Zn, Cu, and Fe, respectively. The content of NDF, ADF, and ADL per dry weight varied from 20 to 31%, 1 to 4.2%, and 0.4 to 2.3%, respectively. Overall, considering the variability among the assessed attributes, heatmap analysis showed the association between each of the traits as related to the clustered genotypes.

The Effects of Processing on Bioactive Compounds and Biological Activities of Sorghum Grains

Sorghum is ranked the fifth most commonly used cereal and is rich in many kinds of bioactive compounds. Food processing can affect the accumulation and decomposition of bioactive compounds in sorghum grains, and then change the biological activities of sorghum grains. The present review aims to analyze the effects of processing technologies on bioactive compounds and the biological activities of sorghum grains. Decortication reduces the total phenols, tannins, and antioxidant activity of sorghum grains. The effects of thermal processes on bioactive compounds and potential biological activities of sorghum grains are complicated due to thermal treatment method and thermal treatment conditions, such as extrusion cooking, which has different effects on the bioactive compounds and antioxidant capacity of sorghum due to extrusion conditions, such as temperature and moisture, and food matrices, such as whole grain and bran. Emerging thermal processes, such as microwave heating and high-pressure processing, could promote the release of bound phenolic substances and procyanidins, and are recommended. Biological processes can increase the nutritive and nutraceutical quality and reduce antinutritional compounds, except for soaking which reduces water-soluble compounds in sorghum.

Genetic diversity for agromorphological traits, phytochemical profile, and antioxidant activity in Moroccan sorghum ecotypes

Sorghum, the fifth most important cereal crop, is a well-adapted cereal to arid/semi-arid regions. Sorghum is known for multiple end-uses as food, feed, fuel, forage, and as source of bioactive compounds that could be used for medical applications. Although the great improvement in the process of sorghum breeding, the average yield of this crop is still very low. Therefore, exploring the genetic diversity in sorghum accessions is a critical step for improving this crop. The main objective of the current work was to study the genetic variation existing in a Moroccan sorghum collection. Indeed, 10 sorghum ecotypes were characterized based on agromorphological descriptors. Both quantitative (25) and qualitative (7) traits revealed variability (p < 0.05) among the studied ecotypes. At the seedling stage, most of the ecotypes showed good to high vigor (70%). However, as the sorghum plants grow, the difference between genotypes become more apparent, especially at the generative phase. For instance, three different panicle shapes have been observed, erect (50%), semi-bent (30%), and bent (20%) with different degree of compactness (20% for loose, semi-compact, and compact panicles, and 30% for semi-loose panicles). In another part of this study, the phytochemical composition and antioxidant activities of the sorghum ecotypes have been determined. The results showed variable total phenolic contents, and total flavonoid contents ranging from 125.86 ± 1.36 to 314.91 ± 3.60 mg GAE/g dw and 114.0 ± 13.2 to 138.5 ± 10.8 (mg catechin equivalent/100 g, dw) respectively, with a differential antioxidant activities as well. These results indicate that for any crop breeding program, it is preferable to take into consideration both morphological and biochemical traits for a better selection of high yielding varieties with high added value compounds. Therefore, the implication of these results in the context of sorghum breeding activities could be a resourceful option for farmers.

Impact of solid-state fermentation on factors and mechanisms influencing the bioactive compounds of grains and processing by-products

Cereal and legume grains and their processing by-products are rich sources of bioactives such as phenolics with considerable health potential, but these bioactives suffer from low bioaccessibility and bioavailability, resulting in limited use. Several studies have demonstrated that solid-state fermentation (SSF) with food-grade microorganisms is effective in releasing bound phenolic compounds in cereal and legume products. In this review, we discuss the effect of SSF on cereal and legume grains and their by-products by examining the role of specific microorganisms, their hydrolytic enzymes, fermentability of agri-food substrates, and the potential health benefits of SSF-enhanced bioactive compounds. SSF with fungi (Aspergillus spp. and Rhizopus spp.), bacteria (Bacillus subtilis and lactic acid bacteria (LAB) spp.) and yeast (Saccharomyces cerevisiae) significantly increased the bioactive phenolics and antioxidant capacities in cereal and legume grains and by-products, mainly through carbohydrate-cleaving enzymes. Increased bioactive phenolic and peptide contents of SSF-bioprocessed cereal and legume grains have been implicated for improved antioxidant, anti-inflammatory, anti-carcinogenic, anti-diabetic, and angiotensin-converting-enzyme (ACE) inhibitory effects in fermented agri-food products, but these remain as preliminary results. Future research should focus on the microbial mechanisms, suitability of substrates, and the physiological health benefits of SSF-treated grains and by-products.

The Sensory Profiles of Flatbreads Made from Sorghum, Cassava, and Cowpea Flour Used as Wheat Flour Alternatives

Sorghum, cowpea, and cassava are underutilised gluten-free sources of flour that have the potential to be used in bread products in sub-Saharan Africa. Excessive wheat imports affect the economies of countries in sub-Saharan Africa, driving the search for wheat flour alternatives. To extend the use of sorghum, cowpea, and cassava flours toward bread production, it is vital that the sensory properties of these flours are better understood. A trained sensory panel evaluated and described the sensory properties of flatbread models prepared from red non-tannin sorghum, fractions (whole and dehulled) of two cowpea varieties, cassava starch, and designated flour composites. The composites were prepared using cassava starch and sorghum flour at 0%, 35%, and 70%, respectively, with 30% cowpea flour. The addition of sorghum intensified sorghum aroma in flatbread, while cowpea flours contributed a beany flavour. Flatbreads from cassava-cowpea composites had a chewier and rubberier mouthfeel, an intense fermented aroma and flavour, and a sour aftertaste compared to single flours, but were most similar to the wheat flatbread, with a residual beany flavour. Information from this study can guide food product developers toward developing new bread products from sorghum, cassava, and cowpea composite flours, thereby moving Africa towards a more sustainable food system. Further research on the effects of the sensory characteristics on consumer liking of the flatbreads is needed.

Bioactive Compounds and Biological Activities of Sorghum Grains

Sorghum is the fifth most commonly used cereal worldwide and is a rich source of many bioactive compounds. We summarized phenolic compounds and carotenoids, vitamin E, amines, and phytosterols in sorghum grains. Recently, with the development of detection technology, new bioactive compounds such as formononetin, glycitein, and ononin have been detected. In addition, multiple in vitro and in vivo studies have shown that sorghum grains have extensive bio-logical activities, such as antioxidative, anticancer, antidiabetic, antiinflammatory, and antiobesity properties. Finally, with the establishment of sorghum phenolic compounds database, the bound phenolics and their biological activities and the mechanisms of biological activities of sorghum bioactive compounds using clinical trials may be researched.

Bread preparation by partial replacement of wheat by germinated sorghum

Published literature shows significant impact of sorghum type and flour on end-product quality, while demonstrating paucity in the studied varieties with respect to processing aspects (such as bread making) despite of enormous accessions available worldwide. Limited studies have reported usage of germinated flour for the above said purpose. The present study thus aimed at mitigating these gaps by utilizing results of sorghum (HJ-513) germination (Day 1-5) and flour derived from optimized condition (Day 3 as identified by partial least square analysis) to develop a composite functional bread (partial replacement of wheat). The germination process enhanced the total phenolics compounds (TPC, till day 3), water (14.01%) and oil absorption capacity (25.97%) while reducing the bulk density (760.99-644.69 kg/m³). This demonstrated increased potential of sorghum flour for development of bakery and confectionery products. The process also affected the pasting properties, total flavonoids compounds (TFC) and DPPH (2, 2-diphenyl-1-picrylhydrazyl) significantly (p < 0.05). The bread developed from partial replacement (10% and 20%) of refined wheat flour by sorghum was hard and darker than the control wheat bread. The bread developed at 20% was more dense and porous than the bread developed with 10% replacement. Specific volume of bread at 10% replacement was found higher than at 20% replacement. The study reports effective utilization of germinated sorghum flour for development of composite-functional bread without incorporation of any other additives/improvers. Future research however is warranted in the field to further increase the replacement of wheat flour by germinated sorghum flour to develop gluten free bread.

Impact of Gluten-Free Sorghum Bread Genotypes on Glycemic and Antioxidant Responses in Healthy Adults

Sorghum is used to provide good quality gluten-free products due to phytochemicals and low glycemic index (GI). This study aimed to determine the chemical composition, the antioxidant activity and capacity, and the glycemic and insulinemic responses of gluten-free (GF) sorghum bread. GF bread samples were produced with three different sorghum genotypes. The samples were analyzed for chemical composition, resistant starch and dietary fiber content; antioxidant activity by ORAC; antioxidant capacity by FRAP; GI; and insulinemic responses. This double-blind, crossover, randomized clinical trial was conducted with 10 healthy men aged 28.0 ± 4.9 years (77.6 ± 11.7 kg and 24.2 ± 2.3 kg/m2). All sorghum bread showed significantly more fiber than rice bread (control). Brown sorghum bread was classified as low GI, bronze and white as medium GI, and control as high GI. Brown sorghum bread presented a low carbohydrate content, a significant amount of fiber, and a significantly lower 3 h AUC glucose response than those of the control, aside from the highest antioxidant activity value (p ≤ 0.001). Therefore, brown sorghum was superior to other genotypes analyzed in this study, and its production should be encouraged to provide gluten-free products with a better nutritional profile. More research is required to explore the effects of different sorghum genotypes in food products on human health.

Delivery of Phenolic Compounds, Peptides and β-Glucan to the Gastrointestinal Tract by Incorporating Dietary Fibre-Rich Mushrooms into Sorghum Biscuits

Sorghum biscuits were enriched with mushroom powders (Lentinula edodes, Auricularia auricula and Tremella fuciformis) at 5%, 10% and 15% substitution levels. An in vitro gastrointestinal digestion was used to evaluate the effect of this enrichment on the phenolic content and soluble peptide content as well as antioxidant activities of the gastric or intestinal supernatants (bio-accessible fractions), and the remaining portions of phenolic compounds, antioxidants and β-glucan in the undigested residue (non-digestible fraction). The phenolic content of the gastric and intestinal supernatants obtained from digested mushroom-enriched biscuits was found to be higher than that of control biscuit, and the phenolic content was positively correlated to the antioxidant activities in each fraction (p < 0.001). L. edodes and T. fuciformis enrichment increased the soluble protein content (small peptide) of sorghum biscuits after in vitro digestion. All mushroom enrichment increased the total phenolic content and β-glucan content of the undigested residue and they were positively correlated (p < 0.001). The insoluble dietary fibre of biscuits was positively correlated with β-glucan content (p < 0.001) of undigested residue. These findings suggested that enriching food with mushroom derived dietary fibre increases the bioavailability of the non-digestible β-glucan and phenolic compounds.

Comparative Study on Seed Characteristics, Antioxidant Activity, and Total Phenolic and Flavonoid Contents in Accessions of Sorghum bicolor (L.) Moench

Sorghum is a major cereal food worldwide, and is considered a potential source of minerals and bioactive compounds. Its wide adaptive range may cause variations in its agronomic traits, antioxidant properties, and phytochemical content. This extensive study investigated variations in seed characteristics, antioxidant properties, and total phenolic (TPC) and flavonoid contents (TFC) of sorghum collected from different ecological regions of 15 countries. The antioxidant potential of the seed extracts of various sorghum accessions was determined using 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2′-azinobis 3-ethylbenzothiazoline-6-sulfonate (ABTS) radical scavenging assays. Significant variations in TPC were observed among the sorghum accessions. All 78 sorghum accessions used in this study exhibited significant variations in TFC, with the lowest and highest amount observed in accessions C465 and J542, respectively. DPPH scavenging potential of the seed extracts for all the accessions ranged from 11.91 ± 4.83 to 1343.90 ± 81.02 µg mL⁻¹. The ABTS assay results were similar to those of DPPH but showed some differences in the accessions. Pearson’s correlation analysis revealed a wide variation range in the correlation between antioxidant activity and TPC, as well as TFC, among the sorghum accessions. A wide diversity range was also recorded for the seed characteristics (1000-seed weight and seed germination rate). A dendrogram generated from UPGMA clustering, based on seed traits, antioxidant activity, TPC, and TFC was highly dispersed for these accessions. Variations among the accessions may provide useful information regarding the phytoconstituents, antioxidant properties, and phytochemical contents of sorghum and aid in designing breeding programs to obtain sorghum with improved agronomic traits and bioactive properties.

Refined sorghum flours precooked by extrusion enhance the integrity of the colonic mucosa barrier and promote a hepatic antioxidant environment in growing Wistar rats

The effects of precooked-refined sorghum flour consumption on antioxidant status, lipid profile, and colonic and bone health were evaluated. Twenty-four male Wistar rats were fed with control diet (C), or red or white precooked-refined sorghum based diets (SD) for 60 days. The intake of SD was lower than that of C, but the efficiency of all diets was similar. Rats fed with SD showed lower feces excretion, cecal pH and enzyme activities (β-glucosidase, β-glucuronidase and mucinase) than C. White SD improved intestinal architecture, cell proliferation and apoptosis, upregulated ZO1 and occludin tight junction proteins and stimulated goblet cell differentiation, enhancing the integrity of the mucosa barrier in both proximal and distal colonic mucosa in a better way than red SD. Consumption of SD significantly decreased serum triglyceride levels compared with the C diet. The mineral content of the right femur was not different among diets. The liver enzyme activities (superoxide dismutase, catalase, glutathione reductase, and glutathione peroxidase) did not show differences among diets. Liver reducing power and reduced glutathione/oxidize glutathione ratio were higher for animals consuming SD than C. It can be concluded that the consumption of precooked refined sorghum flours still has beneficial effects for health, mainly at the colonic level, despite the lower phenolics and fibre contents of refined flours with respect to whole grain flours.

Millet starch: A review

The demand for millets and their products is becoming popular globally due to their various health-promoting properties. The major constituent of the millet is its starch which contributes about 70% of total millet grain and decides the quality of millet-based food products. The application of starch for various purposes is dependent upon its physicochemical, structural, and functional properties. A native starch does not possess all the required properties for a specific use. However, product-specific properties can be achieved by modifying the structure of starches. Information deficit on millet starch has undermined its potential use in new food product design. The objective of this review is to examine the chemical composition, characterization, structural chemistry, digestibility, hydrolysis, and modification techniques of the millet starches. The review paper also discusses the various applications of native and modified starches in the food industry.

Analysis of corn and sorghum flour mixtures using laser-induced breakdown spectroscopy

BACKGROUND

In a world constantly challenged by climate change, corn and sorghum are two important grains because of their high productivity and adaptability, and their multifunctional use for different purposes such as human food, animal feed, and feedstock for many industrial products and biofuels. Corn and sorghum can be utilized interchangeably in certain applications; one grain may be preferred over the other for several reasons. The determination of the composition corn and sorghum flour mixtures may be necessary for economic, regulatory, environmental, functional, or nutritional reasons.

RESULTS

Laser-induced breakdown spectroscopy (LIBS) in combination with chemometrics, was used for the classification of flour samples based on the LIBS spectra of flour types and mixtures using partial least squares discriminant analysis (PLS-DA) and the determination of the sorghum ratio in sorghum / corn flour mixture based on their elemental composition using partial least squares (PLS) regression. Laser-induced breakdown spectroscopy with PLS-DA successfully identified the samples as either pure corn, pure sorghum, or corn-sorghum mixtures. Moreover, the addition of various levels of sorghum flour to mixtures of corn-sorghum flour were used for PLS analysis. The coefficient of determination values of calibration and validation PLS models are 0.979 and 0.965, respectively. The limit of detection of the PLS models is 4.36%.

CONCLUSION

This study offers a rapid method for the determination of the sorghum level in corn-sorghum flour mixtures and the classification of flour samples with high accuracy, a short analysis time, and no requirement for time-consuming sample preparation procedures. © 2020 Society of Chemical Industry.

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).

Mediterranean Gluten-Free Diet: Is It a Fair Bet for the Treatment of Gluten-Related Disorders?

Gluten-free diet (GFD) is the current treatment of gluten-related disorders. It eliminates wheat, barley, and rye, while the exclusion of oats is still under debate. GFD is based on a combination of naturally gluten-free foods and gluten-free substitutes of cereal-based foods. Although effective as treatment of gluten-related disorders, today there is concern about how to improve GFD's nutritional quality, to make it not only gluten-free, but also healthy. The "Mediterranean diet" (MedD) refers to the dietary pattern and eating habits typical of populations living in the Mediterranean basin, which have been associated with low prevalence of several diet-related pathologies. Here we present a narrative review of the current knowledge about GFD and MedD, their characteristics and central food components. Based on the Mediterranean diet pyramid developed by the Italian pediatric society, we propose a combination between the MedD and the GFD, an attractive alternative to reach a gluten-free state that at the same time is healthy, with a clear benefit to those who practice it.

Quinoa Sourdough Fermented with Lactobacillus plantarum ATCC 8014 Designed for Gluten-Free Muffins—A Powerful Tool to Enhance Bioactive Compounds

Lactobacillus plantarum ATCC 8014 was used to ferment quinoa flour, in order to evaluate its influence on the nutritional and rheological characteristics of both the sourdough and muffins. The quantification of carbohydrates and organic acids was carried out on a HPLC-RID system (high-performance liquid chromatography coupled with with refractive index detector), meanwhile HPLC-UV-VIS (high-performance liquid chromatography coupled with UV-VIS detector), AAS (Atomic absorption spectrophotometry), aluminum chloride colorimetric assay, Folin–Ciocalteu, and 1,1-Diphenyl-2-picrylhydrazyl radical scavenging activity (DPPH) methods were used to determine folic acid, minerals, flavonoids, total phenols, and radical scavenging activity, respectively. Two types of sourdough were used in this study: quinoa sourdough fermented with L. plantarum ATCC 8014 and quinoa sourdough spontaneous fermented. The first one influenced the chemical composition of muffins in terms of decreased content of carbohydrates, higher amounts of both organic acids and folic acid. Furthermore, higher amounts of flavonoids, total phenols and increased radical scavenging activity were recorded due to the use of Lactobacillus plantarum ATCC 8014 strain. These results indicate the positive effect of quinoa flour fermentation with the above strain and supports the use of controlled fermentation with lactic acid bacteria for the manufacturing of gluten free baked products.

Influence of germination on physicochemical properties of flours from brown rice, oat, sorghum, and millet

The changes in physiochemical properties of flours obtained from the four selected grains after germination were investigated. After germination, the sprout length of sorghum and millet was substantially larger than that of brown rice and oat. Germination led to a decrease in the apparent amylose content and swelling factor of flours. Gelatinization onset and peak temperatures increased after germination, while a slight decrease was found in conclusion temperature. Compared to the raw flours, the germinated flours derived from brown rice, sorghum, and millet had lower gelatinization enthalpy, whereas the germinated oat flour showed higher gelatinization enthalpy. Germination resulted in significant decrease in pasting parameters of the four flours. Amylose leaching of sorghum and millet flours increased after germination, while the brown rice and oat flours showed a significant decrease in amylose leaching. Results suggest that germination effectively altered the physicochemical properties of grain flours, which can be utilized as functional ingredient in the preparation of grain-based products.

African Sorghum-Based Fermented Foods: Past, Current and Future Prospects

Sorghum (Sorghum bicolor) is a well-known drought and climate resistant crop with vast food use for the inhabitants of Africa and other developing countries. The importance of this crop is well reflected in its embedded benefits and use as a staple food, with fermentation playing a significant role in transforming this crop into an edible form. Although the majority of these fermented food products evolve from ethnic groups and rural communities, industrialization and the application of improved food processing techniques have led to the commercial success and viability of derived products. While some of these sorghum-based fermented food products still continue to bask in this success, much more still needs to be done to further explore evolving techniques, technologies and processes. The addition of other affordable nutrient sources in sorghum-based fermented foods is equally important, as this will effectively augment the intake of a nutritionally balanced product.

Effect of the nixtamalization process on the protein bioaccessibility of white and red sorghum flours during in vitro gastrointestinal digestion

Protein bioaccessibility is a major concern in sorghum (Sorghum bicolor L. Moench) due to potential interactions with tannins affecting its nutritional value. Technological treatments such as boiling or alkaline cooking have been proposed to address this problem by reducing tannin-protein interactions. This research aimed to evaluate the impact of nixtamalization in the protein bioaccessibility from two sorghum varieties (red and white sorghum) during in vitro gastrointestinal digestion. Nixtamalization increased protein bioaccessibility in the non-digestible fraction (NDF) (5.26 and 26.31% for red and white sorghum, respectively). However, cooking showed a higher permeation speed of protein from red sorghum flours at the end of the intestinal incubation (9.42%). The SDS-PAGE profile of the digested fraction (DF) at 90 min of intestinal incubation indicated that, for red sorghum, cooking allows the formation of α and γ-kafirins while nixtamalization increase α-kafirin release. Principal Components Analysis (PCA) showed the association between nixtamalization and dissociation of δα kafirin complexes and increased protein content in the digestible fraction. In silico interactions indicated the highest biding energies for (+)-catechin and kafirin fractions (β-kafirin: -7.0 kcal/mol; γ-kafirin: -5.8 kcal/mol, and δ-kafirin: -6.8 kcal/mol), suggesting a minor influence of depolymerized proanthocyanidin fractions with sorghum proteins as a result of the nixtamalization process. In conclusion, nixtamalization increased the bioaccessibility of sorghum proteins, depolymerizing condensed tannins, and breaking protein-tannin complexes. Such technological process improves the nutrimental value of sorghum, supporting its inclusion in the human diet.

Lactic Fermentation as a Strategy to Improve the Nutritional and Functional Values of Pseudocereals

One of the greatest challenges is to reduce malnutrition worldwide while promoting sustainable agricultural and food systems. This is a daunting task due to the constant growth of the population and the increasing demands by consumers for functional foods with higher nutritional values. Cereal grains are the most important dietary energy source globally; wheat, rice, and maize currently provide about half of the dietary energy source of humankind. In addition, the increase of celiac patients worldwide has motivated the development of gluten-free foods using alternative flour types to wheat such as rice, corn, cassava, soybean, and pseudocereals (amaranth, quinoa, and buckwheat). Amaranth and quinoa have been cultivated since ancient times and were two of the major crops of the Pre-Colombian cultures in Latin- America. In recent years and due to their well-known high nutritional value and potential health benefits, these pseudocereals have received much attention as ideal candidates for gluten-free products. The importance of exploiting these grains for the elaboration of healthy and nutritious foods has forced food producers to develop novel adequate strategies for their processing. Fermentation is one of the most antique and economical methods of producing and preserving foods and can be easily employed for cereal processing. The nutritional and functional quality of pseudocereals can be improved by fermentation using Lactic Acid Bacteria (LAB). This review provides an overview on pseudocereal fermentation by LAB emphasizing the capacity of these bacteria to decrease antinutritional factors such as phytic acid, increase the functional value of phytochemicals such as phenolic compounds, and produce nutritional ingredients such as B-group vitamins. The numerous beneficial effects of lactic fermentation of pseudocereals can be exploited to design novel and healthier foods or grain ingredients destined to general population and especially to patients with coeliac disease.

Recent Advances in the Use of Sourdough Biotechnology in Pasta Making

The growing consumers’ request for foods with well-balanced nutritional profile and functional properties promotes research on innovation in pasta making. As a staple food and a common component of diet, pasta can be considered as a vector of dietary fiber, vegetable proteins, vitamins, minerals, and functional compounds. The conventional process for pasta production does not include a fermentation step. However, novel recipes including sourdough-fermented ingredients have been recently proposed, aiming at enhancing the nutritional and functional properties of this product and at enriching commercial offerings with products with new sensorial profiles. The use of sourdough for pasta fortification has been investigated under several aspects, including fortification in vitamin B, the reduction of starch digestibility, and gluten content. Sourdough fermentation has also been successfully applied to non-conventional flours, (e.g., from pseudocereals and legumes), in which an overall increase of the nutritional value and health-promoting compounds, such as a significant decrease of antinutritional factors, were observed. Fermented non-conventional flours, obtained through spontaneous fermentation or using selected starters, have been proposed as pasta ingredients. As the result of wheat replacement, modification in textural properties of pasta may occur. Nonetheless, fermentation represents an efficient tool in improving, besides nutritional and functional profile, the sensory and technological features of fortified pasta.

Untargeted Metabolomics Reveal Defensome-Related Metabolic Reprogramming in Sorghum bicolor against Infection by Burkholderia andropogonis

Burkholderia andropogonis is the causal agent of bacterial leaf stripe, one of the three major bacterial diseases affecting Sorghum bicolor. However, the biochemical aspects of the pathophysiological host responses are not well understood. An untargeted metabolomics approach was designed to understand molecular mechanisms underlying S. bicolor⁻B. andropogonis interactions. At the 4-leaf stage, two sorghum cultivars (NS 5511 and NS 5655) differing in disease tolerance, were infected with B. andropogonis and the metabolic changes monitored over time. The NS 5511 cultivar displayed delayed signs of wilting and lesion progression compared to the NS 5655 cultivar, indicative of enhanced resistance. The metabolomics results identified statistically significant metabolites as biomarkers associated with the sorghum defence. These include the phytohormones salicylic acid, jasmonic acid, and zeatin. Moreover, metabolic reprogramming in an array of chemically diverse metabolites that span a wide range of metabolic pathways was associated with the defence response. Signatory biomarkers included aromatic amino acids, shikimic acid, metabolites from the phenylpropanoid and flavonoid pathways, as well as fatty acids. Enhanced synthesis and accumulation of apigenin and derivatives thereof was a prominent feature of the altered metabolomes. The analyses revealed an intricate and dynamic network of the sorghum defence arsenal towards B. andropogonis in establishing an enhanced defensive capacity in support of resistance and disease suppression. The results pave the way for future analysis of the biosynthesis of signatory biomarkers and regulation of relevant metabolic pathways in sorghum.

Whole cereal grains and potential health effects: Involvement of the gut microbiota

The intakes of whole cereal grains (WCGs) have long been linked to decreased risks of metabolic syndromes (MetS) and several chronic diseases. Owing to the complex range of components of cereals, which may show synergistic activities to mediate these protective effects, the mechanisms by which the benefits of whole cereals arise are not fully understood. The gut microbiota has recently become a new focus of research at the intersection of diet and metabolic health. Moreover, cereals contain various ingredients known as microbiota-accessible substrates that resist digestion in the upper gastrointestinal tract, including resistant starch and non-starch polysaccharides such as β-glucan and arabinoxylans, making them an important fuel for the microbiota. Thus, WCGs may manipulate the ecophysiology of gut microbiota. In this review, the scientific evidence supporting the hypothesis that WCGs prevent MetS by modulating gut microbiota composition and functions are discussed, with focuses on cereal intake-related mechanisms by which gut microbiota contributes to human health and scientific evidences for the effects of WCGs on modulating gut microbiota. Once strong support for the association among WCGs, gut microbiota and host metabolic health can be demonstrated, particular cereals, their processing technologies, or cereal-based foods might be better utilized to prevent and possibly even treat metabolic disease.