Pericarp thickness of sorghum whole grain is accurately predicted by NIRS and can affect the prediction of other grain quality parameters

Sorghum phytonutrients and their health benefits: A systematic review from cell to clinical trials

Sorghum is key for global food security due to its genetic variability, resilience, and rich phytonutrient content, which are linked to numerous health benefits. A systematic review assessed the health effects of sorghum by analyzing cell (n = 22), animal (n = 20), and human (n = 7) studies across antioxidant, anti-inflammatory, obesity, cancer, cardiovascular, and diabetes outcomes. This review, involving 42 papers and 177 researchers from 12 countries, collected data from sorghum accessions (acc) and significant effects. Studies used 68 identified and 8 unidentified sorghums, 57% red (n = 20), brown (n = 5), and black (n = 17) pericarp colors, and evaluated whole (n = 31), brans (n = 11), and decorticated grains (n = 2). Colored sorghum, richer in phenolic compounds, especially 3-deoxyanthocyanins and tannins, inhibited cancer cell activities, including proliferation, tumor growth, and ROS activity, and promoted cell cycle arrest and apoptosis. Sorghum elevated HO1 and eNOS expression for cardiovascular, health-reduced platelet aggregation, and modulated platelet microparticles. They also suppressed inflammation markers and decreased lipid accumulation. Animal studies indicated sorghum's potential across antioxidant capacity, cancer and inflammation mitigation, and lipid and glucose metabolism. Translating these findings to human scenarios requires caution, especially considering cell studies do not fully represent polyphenol metabolism. Human studies provided mixed results, indicating antioxidant and potential anti-inflammatory benefits and nuanced effects on glucose and lipid metabolism. The main risks of bias highlighted challenges in quantifying phytonutrients, identifying sorghum acc features, and lack of assessors blinding. Nonetheless, sorghum emerges as a promising functional food for countering chronic diseases in Western diets.

Classification and characterization on sorghums based on HS-GC-IMS combined with OPLS-DA and GA-PLS

Headspace gas chromatography-ion mobility spectrometry (HS-GC-IMS) detected 206 and 186 samples of fresh and stored sorghums respectively with three major types in Baijiu industry. The fingerprints showed the differences of volatile compounds among fresh sorghum types by qualitative analysis and artificial recognition. Organic waxy sorghums had more contents of nonanal and 2-ethyl-1-hexanol but fewer ketones. The contents of acetoin in non-glutinous sorghums and organic non-glutinous sorghums were high. On the other hand, genetic algorithm-partial least squares (GA-PLS) selected 19 and 32 characteristic volatile compounds in fresh and stored sorghums. After centering and auto scaling to unit variance, the classification models with three major types of organic waxy sorghum, non-glutinous sorghum and organic non-glutinous sorghum were established based on orthogonal partial least squares-discriminant analysis (OPLS-DA). The goodness-of-fit (R2Y) and the goodness-of-prediction in cross-validation (Q2) in the model of fresh sorghum types all exceeded 0.9, in stored were over 0.8, the correct classification rates of external prediction were 95 % and 100 %, which revealed good performance and prediction. On this basis, the correct classification rates reached 87 % in organic waxy sorghums adulterated over 10 % ratio. GC-IMS combined with chemometrics is applicable in practical production for rapid identification of sorghum types and adulterations.

Formulation of a Synergistic Enzyme Cocktail for Controlled Degradation of Sorghum Grain Pericarp

Sorghum is one of the major grains produced worldwide for food and fodder, owing to its nutritional profile advantages. However, the utilisation of whole grain sorghum as an ingredient in conventional food formulations is limited due to its poor digestibility, which requires the removal of the outer fibrous layers. Grain breakage and loss of essential nutrients also disadvantage traditional milling practices. Using carbohydrate degrading enzymes to hydrolyse the grain pericarp is a novel approach to biopolishing, where selective degradation of the pericarp layers occurs without adversely affecting the nutrient profile. A collective synergism of enzymes has been proven to cause effective hydrolysis compared to individual enzymes due to the complex presence of non-starch polysaccharides in the grain's outer layers, which comprise a variety of sugars that show specific degradation with respect to each enzyme. The present study aimed to formulate such an enzyme cocktail with xylanase, cellulase, and pectinase in different proportions for hydrolysing sorghum grain pericarp by determining the yield of specific sugars in the pericarp extract after a certain period of incubation. The results showed that the xylanase enzyme has a major effect on the grain bran composition compared to cellulase and pectinase; however, a synergistic mixture yielded more hydrolysed sugars and anti-nutrients in the extract compared to each of the enzymes individually. The results were confirmed by morphological and crystallinity studies of the soaked grain. Compared to conventional water-soaked samples, grains soaked in a cocktail with 66.7% xylanase, 16.7% cellulase, and 16.7% pectinase had visibly thinner and more degraded fibre layers.

Non-Destructive Direct Pericarp Thickness Measurement of Sorghum Kernels Using Extended-Focus Optical Coherence Microscopy

Non-destructive measurements of internal morphological structures in plant materials such as seeds are of high interest in agricultural research. The estimation of pericarp thickness is important to understand the grain quality and storage stability of seeds and can play a crucial role in improving crop yield. In this study, we demonstrate the applicability of fiber-based Bessel beam Fourier domain (FD) optical coherence microscopy (OCM) with a nearly constant high lateral resolution maintained at over ~400 µm for direct non-invasive measurement of the pericarp thickness of two different sorghum genotypes. Whereas measurements based on axial profiles need additional knowledge of the pericarp refractive index, en-face views allow for direct distance measurements. We directly determine pericarp thickness from lateral sections with a 3 µm resolution by taking the width of the signal corresponding to the pericarp at the 1/e threshold. These measurements enable differentiation of the two genotypes with 100% accuracy. We find that trading image resolution for acquisition speed and view size reduces the classification accuracy. Average pericarp thicknesses of 74 µm (thick phenotype) and 43 µm (thin phenotype) are obtained from high-resolution lateral sections, and are in good agreement with previously reported measurements of the same genotypes. Extracting the morphological features of plant seeds using Bessel beam FD-OCM is expected to provide valuable information to the food processing industry and plant breeding programs.

Sorghum in foods: Functionality and potential in innovative products

Sorghum grain is a staple food for about 500 million people in 30 countries in Africa and Asia. Despite this contribution to global food production, most of the world's sorghum grain, and nearly all in Western countries, is used as animal feed. A combination of the increasingly important ability of sorghum crops to resist heat and drought, the limited history of the use of sorghum in Western foods, and the excellent functional properties of sorghum grain in healthy diets, suggests a greater focus on the development of new sorghum-based foods. An understanding of the structural and functional properties of sorghum grain to develop processes for production of new sorghum-based foods is required. In this review, we discuss the potential of sorghum in new food products, including sorghum grain composition, the functional properties of sorghum in foods, processing of sorghum-based products, the digestibility of sorghum protein and starch compared to other grains, and the health benefits of sorghum. In the potential for sorghum as a major ingredient in new foods, we suggest that the gluten-free status of sorghum is of relatively minor importance compared to the functionality of the slowly digested starch and the health benefits of the phenolic compounds present.

Gluten-Free Sorghum Pasta: Composition and Sensory Evaluation with Different Sorghum Hybrids

Although whole grain (WG) sorghum is affordable and a healthier alternative to gluten-free pastas (GFPa), sorghum diversity requires evaluation for application in pasta. We aimed to develop GFPa using six sorghum hybrids. White commercial flour (WCF) and sorghums with brown (BRS 305 and 1167048), red (BRS 330 and BRS 332), and white (CMSXS 180) pericarp colors. Total phenolic content (TPC), total condensed tannins (TAN), total antioxidant activity (TAA—FRAP and DPPH), resistant starch (RS), cooking properties, texture, and sensory evaluation were carried out in sorghum pasta. The statistical analyses were ANOVA, Tukey and Friedman test, and multiple factorial analyses. Brown sorghum GFPa showed the best results for bioactive compounds (RS (1.8 and 2.9 g/100 g), TPC (69.9 and 42.8 mg/100 g), TAN (16.9 and 9.4 mg proanthocyanidin/100 g), TAA for FRAP (305 and 195 mM Teq/g), and DPPH (8.7 and 9.0 mg/mL)), but also the highest soluble solids loss (8.0 g/100 g) and lower flavor acceptance for BRS 305. BRS 332 was highlighted for its higher flavor acceptance and intermediary phenolics content. The most accepted pasta was obtained with WCF, and the least accepted with the brown BRS 305. Sweetness (SWE), soluble starch (SS), and DPPH were associated with liking. The main negative variables were WG_flavor, brown color, FRAP, sandy surface (SAN), WG_odor, and TAN. Sorghum hybrids of different pericarp colors are feasible for GFPa production, leading to differences in pasta quality. SAN and GRA, associated with disliking in antioxidant-rich GFPa, could be improved by milling process adjustments. Increasing the SS proportion and SWE with flavors can contribute to the balance between liking and nutritional advantages.

Characterisation of Polishing Frequency for Three Varieties of Sorghum Grain in Java, Indonesia

To determine the suitability of different sorghum cultivars (grown in Indonesia) for the manufacturing of acceptable food products, their properties must first be characterised. During sorghum processing, polishing may affect the final nutritional value and quality of the product. This study is aimed at determining the effects of sorghum variety and polishing frequency on nutritional value. This was achieved by using a factorial randomised block design with two factors: sorghum variety (Bioguma, Numbu, and Super) and polishing frequency (once, twice, or thrice). Tannin content, antioxidant capacity, levels of dietary fibre and resistant starch, and fat, ash, and carbohydrate content varied according to sorghum cultivar. Compared to other sorghum varieties, the Super cultivar contained the highest levels of antioxidants, dietary fibre, fat content, protein, resistant starch, and tannins (although high tannin content could be lowered by polishing grains up to three times). The frequency of polishing affected tannin and ash levels in all three sorghum varieties. Polishing frequency also affected the antioxidant capacity of polished sorghum grains. The findings from this study should be considered when determining appropriate applications for various sorghum-based food products.

Sorghum Grains Grading for Food, Feed, and Fuel Using NIR Spectroscopy

Near-infrared spectroscopy (NIR) is a non-destructive, fast, and low-cost method to measure the grain quality of different cereals. However, the feasibility for determining the critical biochemicals, related to the classifications for food, feed, and fuel products are not adequately investigated. Fourier-transform (FT) NIR was applied in this study to determine the eight biochemicals in four types of sorghum samples: hulled grain flours, hull-less grain flours, whole grains, and grain flours. A total of 20 hybrids of sorghum grains were selected from the two locations in China. Followed by FT-NIR spectral and wet-chemically measured biochemical data, partial least squares regression (PLSR) was used to construct the prediction models. The results showed that sorghum grain morphology and sample format affected the prediction of biochemicals. Using NIR data of grain flours generally improved the prediction compared with the use of NIR data of whole grains. In addition, using the spectra of whole grains enabled comparable predictions, which are recommended when a non-destructive and rapid analysis is required. Compared with the hulled grain flours, hull-less grain flours allowed for improved predictions for tannin, cellulose, and hemicellulose using NIR data. This study aimed to provide a reference for the evaluation of sorghum grain biochemicals for food, feed, and fuel without destruction and complex chemical analysis.

Genetic dissection of sorghum grain quality traits using diverse and segregating populations

KEY MESSAGE

Coordinated association and linkage mapping identified 25 grain quality QTLs in multiple environments, and fine mapping of the Wx locus supports the use of high-density genetic markers in linkage mapping. There is a wide range of end-use products made from cereal grains, and these products often demand different grain characteristics. Fortunately, cereal crop species including sorghum [Sorghum bicolor (L.) Moench] contain high phenotypic variation for traits influencing grain quality. Identifying genetic variants underlying this phenotypic variation allows plant breeders to develop genotypes with grain attributes optimized for their intended usage. Multiple sorghum mapping populations were rigorously phenotyped across two environments (SC Coastal Plain and Central TX) in 2 years for five major grain quality traits: amylose, starch, crude protein, crude fat, and gross energy. Coordinated association and linkage mapping revealed several robust QTLs that make prime targets to improve grain quality for food, feed, and fuel products. Although the amylose QTL interval spanned many megabases, the marker with greatest significance was located just 12 kb from waxy (Wx), the primary gene regulating amylose production in cereal grains. This suggests higher resolution mapping in recombinant inbred line (RIL) populations can be obtained when genotyped at a high marker density. The major QTL for crude fat content, identified in both a RIL population and grain sorghum diversity panel, encompassed the DGAT1 locus, a critical gene involved in maize lipid biosynthesis. Another QTL on chromosome 1 was consistently mapped in both RIL populations for multiple grain quality traits including starch, crude protein, and gross energy. Collectively, these genetic regions offer excellent opportunities to manipulate grain composition and set up future studies for gene validation.