Impact of sprouting on physicochemical and nutritional properties of sorghum: a review

Tracking the changes and bioaccessibility of phenolic compounds of sorghum grains (Sorghum bicolor (L.) Moench) upon germination and seedling growth by UHPLC-QTOF-MS/MS

In this study, phenolic profile/content was analyzed by high-resolution untargeted metabolomics after short germination (72 h) and seedling growth (144 h), using three sorghum genotypes varying in tannin content (IS 29569, Macia and IS 30400). In vitro antioxidant capacity and phenolic bioaccessibility were determined by microplate-based and INFOGEST methods, respectively. A total of 58 % annotated compounds were found in all genotypes; and phenolic acids and flavonoids represent more than 80 % of sorghum total abundance. PCA analysis showed higher phenolic variability in germination times (72 %) than genotypes (51 %). Germination reduced total ion abundance (-7 %) and free:bound phenolic compounds ratio (2.4-1.1), but antioxidant capacity remained constant. These results indicate the cell matrix-phenolic decomplexation, with the free compounds were quickly consumed after radicle emergence. Germination increased phenolic bioaccessibility (mainly in oral phase) but reduces flavonoids contents in gastric/intestinal digestion steps. This work can stimulate seed germination as a viable option for sorghum-based foods development, with improved nutritional and bioactive properties.

Effect of ultrasonically stimulated potato germination during soaking on the physicochemical properties of starch and its use in edible films

The aim of this work was to investigate the effects of ultrasonic treatment during soaking of potatoes on the physicochemical properties of starches obtained after 16 weeks of germination. The ultrasonic treatment showed a direct correlation between sprout length and ultrasonic time. The protein content decreased from 0.63 to 0.38 % and the fat content decreased significantly from 0.31 to 0.01 % after germination. The amylose content changed depending on the ultrasonic treatment, and increased from 36.27 to 40.92 % after 16 weeks of germination, which was related to the amylopectin debranching and the duration of the ultrasonic treatment. X-ray diffraction showed that the nanocrystals with hexagonal structure were not affected by the germination and the duration of ultrasonic treatment. Scanning electron microscopy showed that the surface of the starch granules was not affected by the enzymatic treatment. The sprouted potato starch resulted in films with better tensile strength and lower water vapor permeability (WVP) compared to the native potato starch films. In addition, the films produced with ultrasound stimulated potato starch exhibited better properties (high strength and low permeability), which is desirable when it comes to controlling moisture exchange between a food product and the surrounding atmosphere.

Expression of heterosis in photosynthetic traits in F1 generation of sorghum (Sorghum bicolor) hybrids and relationship with yield traits

Heterosis is a crucial factor in enhancing crop yield, particularly in sorghum (Sorghum bicolor ). This research utilised six sorghum restorer lines, six sorghum sterile lines, and 36 hybrid combinations created through the NCII incomplete double-row hybridisation method. We evaluated the performance of F1 generation hybrids for leaf photosynthesis-related parameters, carbon metabolism-related enzymes, and their correlation with yield traits during the flowering stage. Results showed that hybrid sorghum exhibited significant high-parent heterosis in net photosynthetic rate (P n ), transpiration rate (T r ), stomatal conductance (G s ), apparent leaf meat conductance (AMC), ribulose-1,5-bisphosphate (RuBP) carboxylase, phosphoenolpyruvate (PEP) carboxylase, and sucrose phosphate synthase (SPS). Conversely, inter-cellular carbon dioxide concentration (C i ), instantaneous water uses efficiency (WUE), and sucrose synthase (SuSy) displayed mostly negative heterosis. Traits such as 1000-grain weight (TGW), grain weight per spike (GWPS), and dry matter content (DMC) exhibited significant high-parent heterosis, with TGW reaching the highest value of 82.54%. P n demonstrated positive correlations with T r , C i , G s , RuBP carboxylase, PEP carboxylase, GWPS, TGW, and DMC, suggesting that T r , C i , and G s could aid in identifying high-photosynthesis sorghum varieties. Concurrently, P n could help select carbon-efficient sorghum varieties due to its close relationship with yield. Overall, the F1 generation of sorghum hybrids displayed notable heterosis during anthesis. Combined with field performance, P n at athesis can serve as a valuable indicator for early prediction of the yield potential of the F1 generation of sorghum hybrids and for screening carbon-efficient sorghum varieties.

Effect of water content on gelatinization functionality of flour from sprouted sorghum

Sorghum starch granules are encapsulated in a rigid protein matrix that prevents the granules from fully swelling and gelatinizing. Sprouting and subsequent drying treatment can affect the gelatinization properties of sorghum starch. This study aimed to evaluate the gelatinization properties of flours from unsprouted (US) and sprouted (S50, S40) sorghum dried at 50 °C (6h) and 40 °C (12h), respectively. Swelling power (Sp), thermal properties (DSC) and 1H molecular mobility and dynamics were evaluated at different water contents (38-91%). Sp increased with increasing water content, with S40 showing the lowest values, probably due to prolonged amylase activity and thus starch breakdown. Sprouting increased gelatinization temperatures; however, these differences disappeared for high water contents (82 and 91%). From a molecular point of view, sprouted samples showed a decrease in protons associated to the rigid protein matrix and starch structures. 1H CPMG results showed the presence of 4 populations at 38% water content. The evolution of the more mobile population with increasing water content supported the assignment of more mobile water fraction to this population. Sprouting decreased the mobility of populations in unheated samples, suggesting an increase in molecular bonds between flour biopolymers and water. After heating, however, increased molecular mobility in S40 indicated the formation of a weaker network between starch, protein, and water at the molecular level. These results suggest that post-sprouting drying treatment influences sorghum gelatinization, with potential modulation by water content. This study contributes to understanding the application of sprouted sorghum in foods with different moisture content.

Exploring the Impacts of Sorghum (Sorghum bicolor L. Moench) Germination on the Flour's Nutritional, Chemical, Bioactive, and Technological Properties

Germination is a natural, simple, and economical process used to improve the quality of nutritional and technological grains. In this study, native and sprouted sorghum flours were characterized regarding their technological properties (particle size distribution, water, and oil absorption capacity, swelling power and solubility, microscopy of starch granules, and pasting and thermal properties). Nutritional and phytochemical characterization profiles, including free sugars, fatty acids, organic acids, tocopherols, and phenolic compounds, were explored through chromatographic methods. The antioxidant, anti-inflammatory, and cytotoxic activities of the respective hydroethanolic extracts were also evaluated. The results showed that the germination process caused significant changes in the flour composition and properties, causing reduced gelatinization temperature and retarded starch retrogradation; an increased content of free sugars and total organic acids; and a decreased content of tocopherols and phenolic compounds. In terms of bioactivity, the sprouted sorghum flour extract showed better lipid-peroxidation-inhibition capacity and none of the extracts revealed hepatotoxicity or nephrotoxicity, which are important results for the validation of the use of the flours for food purposes. Germination is an efficient and alternative method for grain modification that gives improved technological properties without chemical modification or genetic engineering.

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.

Effect of Sprouting on Biomolecular and Antioxidant Features of Common Buckwheat (Fagopyrum esculentum)

Buckwheat is a pseudo-cereal widely grown and consumed throughout the world. Buckwheat is recognized as a good source of nutrients and, in combination with other health-promoting components, is receiving increasing attention as a potential functional food. Despite the high nutritional value of buckwheat, a variety of anti-nutritional features makes it difficult to exploit its full potential. In this framework, sprouting (or germination) may represent a process capable of improving the macromolecular profile, including reducing anti-nutritional factors and/or synthesizing or releasing bioactives. This study addressed changes in the biomolecular profile and composition of buckwheat that was sprouted for 48 and 72 h. Sprouting increased the content of peptides and free-phenolic compounds and the antioxidant activity, caused a marked decline in the concentration of several anti-nutritional components, and affected the metabolomic profile with an overall improvement in the nutritional characteristics. These results further confirm sprouting as a process suitable for improving the compositional traits of cereals and pseudo-cereals, and are further steps towards the exploitation of sprouted buckwheat as a high-quality ingredient in innovative products of industrial interest.

Recent developments in physical invigoration techniques to develop sprouts of edible seeds as functional foods

For nutritional security, the availability of nutrients from food sources is a crucial factor. Global consumption of edible seeds including cereals, pulses, and legumes makes it a valuable source of nutrients particularly vitamins, minerals, and fiber. The presence of anti-nutritional factors forms complexes with nutrients, this complexity of the nutritional profile and the presence of anti-nutritional factors in edible seeds lead to reduced bioavailability of nutrients. By overcoming these issues, the germination process may help improve the nutrient profile and make them more bioavailable. Physical, physiological, and biological methods of seed invigoration can be used to reduce germination restraints, promote germination, enhance early crop development, to increase yields and nutrient levels through sprouting. During sprouting early start of metabolic activities through hydrolytic enzymes and resource mobilization causes a reduction in emergence time which leads to a better nutritional profile. The use of physical stimulating methods to increase the sprouting rate gives several advantages compared to conventional chemical-based methods. The advantages of physical seed treatments include environment-friendly, high germination rate, early seedling emergence, uniform seedling vigor, protection from chemical hazards, and improved yield. Different physical methods are available for seed invigoration viz. gamma irradiation, laser irradiation, microwaves, magnetic field, plasma, sound waves, and ultrasonic waves. Still, further research is needed to apply each technique to different seeds to identify the best physical method and factors for seed species along with different environmental parameters. The present review will describe the use and effects of physical processing techniques for seed invigoration.

Comprehensive transcriptomic and metabolomic profiling reveals the differences between alfalfa sprouts germinated with or without light exposure

Alfalfa sprouts are among the most nutritionally rich foods, and light exposure is a critical factor in determining their biomass and quality. However, detailed metabolic and molecular differences between yellow and green alfalfa sprouts remain unclear. In this study, comprehensive metabolomic and transcriptomic analyses were integrated to evaluate the nutrient composition of alfalfa sprouts during germination with or without light exposure. Differentially expressed genes and differentially accumulated metabolites in green and yellow alfalfa sprouts were significantly enriched in secondary metabolic pathways, such as the isoflavonoid biosynthesis pathway. Green alfalfa sprouts contained a wide variety of lipids, flavonoids, phenolic acids, and terpenoids, among which the top three upregulated were calycosin, methyl gallate, and epicatechin 3-gallate, whereas yellow alfalfa sprouts contained relatively more isoquercitrin. These results provide new insights into the nutritional value and composition of alfalfa sprouts under different germination regimes.

The Fabrication and Characterization of Pickering Emulsion Gels Stabilized by Sorghum Flour

Pickering emulsion gels have potential application as solid fat substitutes and nutraceutical carriers in foods, but a safe and easily available food-derived particle emulsifier is the bottleneck that limits their practical application. In this study, the function of sorghum flour as a particle emulsifier to stabilize the oil-in-water (O/W) Pickering emulsion gels with medium chain triglycerides (MCT) in the oil phase was introduced. Sorghum flour had suitable size distribution (median diameter, 21.47 μm) and wettability (contact angle, 38°) and could reduce the interfacial tension between MCT and water. The oil phase volume fraction (φ) and the addition amount of sorghum flour (c) had significant effects on the formation of Pickering emulsion gels. When c ≥ 5%, Pickering emulsion gels with φ = 70% could be obtained. Microstructure analysis indicated that sorghum flour not only played an emulsifying role at the O/W interface but also prevented oil droplets from coalescing through its viscous effect in the aqueous phase. With increases in c, the droplet size of the emulsion gel decreased, its mechanical properties gradually strengthened, and its protective effect on β-carotene against UV irradiation also improved.