Latent Anti-nutrients and Unintentional Breeding Consequences in Australian Sorghum bicolor Varieties

Abstract

Modern feed quality sorghum grain has been bred to reduce anti-nutrients, most conspicuously condensed tannins, but its inclusion in the diets of monogastric animals can still result in variable performance that is only partially understood. Sorghum grain contains several negative intrinsic factors, including non-tannin phenolics and polyphenols, phytate, and kafirin protein, which may be responsible for these muted feed performances. To better understand the non-tannin phenolic and polyphenolic metabolites that may have negative effects on nutritional parameters, the chemical composition of sorghum grain polyphenol extracts from three commercial varieties (MR-Buster, Cracka, and Liberty) was determined through the use of an under-studied, alternative analytical approach involving Fourier-transform infrared (FT-IR) spectroscopy and direct ionization mass spectrometry. Supervised analyses and interrogation of the data contributing to variation resulted in the identification of a variety of metabolites, including established polyphenols, lignin-like anti-nutrients, and complex sugars, as well as high levels of fatty acids which could contribute to nutritional variation and underperformance in monogastrics. FT-IR and mass spectrometry could both discriminate among the different sorghum varieties indicating that FT-IR, rather than more sophisticated chromatographic and mass spectrometric methods, could be incorporated into quality control applications.

Concentration of Pro-Health Compound of Sorghum Grain-Based Foods

“…Characteristic for the protein composition of this grain is the lack of gluten, and its grains are low in lysine. In vitro and in vivo studies on farm and laboratory animals indicate that sorghum proteins are generally less digestible than those of other cereals [ 80 ]. The digestibility of sorghum is 74.5%, compared to 78.5% for maize [ 79 , 80 ].…”

“…In vitro and in vivo studies on farm and laboratory animals indicate that sorghum proteins are generally less digestible than those of other cereals [ 80 ]. The digestibility of sorghum is 74.5%, compared to 78.5% for maize [ 79 , 80 ]. The bioavailability of iron in sorghum is negatively affected by the presence of polyphenols and phytates.…”

“…Scientists conducted animal studies that proved that tannin inhibits protein absorption and reduces the use of minerals [ 79 ]. Feeding pigs with feed containing 4.21% tannin reduced protein digestibility by 5.6% [ 80 ]. The tannin content in unripe and dark grains is always higher than in ripe and light grains.…”

“…Sorghum also contains phytic acid, phytates that form complexes with minerals such as calcium, iron, and magnesium, making them biologically inaccessible for absorption. Studies have shown that sorghum bran contained the highest levels of phytates [ 80 ]. The last group of anti-nutritional substances are cyanogenic glycosides, the representative of which, i.e., dhurrin, is present mainly in the leaves and germinating seeds of sorghum.…”

Potential food applications of sorghum (Sorghum bicolor) and rapid screening methods of nutritional traits by spectroscopic platforms

“…Further, the qualitative results of FTIR reveal the bond structure, and hence extracted unknown compounds can be identified without standards (Slima et al, 2018). Moreover, the spectral data from the O─H group helps to identify phenolic compounds such as flavonoids and tannins and is sensitive to subtle variations in the structure (Azubuike et al, 2016;Hodges et al, 2021). The compounds can be quantified by calibration models, and the comparisons of different sorghum samples is more efficient than chromatography separations.…”