A team of researchers led by Stephen Olaide Aremu and corresponding author Caleb Zando, working with colleagues at the Federal University of Lafia and partner institutions, purchased edible tubers of both species from multiple vendors at the Lafia Modern Market to ensure representative sampling. The varietal identities were confirmed with the university’s Department of Agronomy before the tubers were peeled, sliced, and carefully oven-dried at temperatures gradually raised from 60 to 110 degrees Celsius over eighteen hours to avoid hardening. The dried samples were ground into fine powder and subjected to a battery of standardized analytical methods drawn from the Association of Official Analytical Chemists, including micro-Kjeldahl nitrogen determination, permanganate titration for oxalates, ferric chloride titration for phytates, and alkaline titration for cyanogenic glycosides.

The proximate analysis delivered a clear first verdict: the potato wins on protein. Solanum tuberosum registered 14.27 percent crude protein against 11.76 percent for Dioscorea rotundata, a figure the authors note is substantially higher than most previously published values for both crops. Potato proteins, dominated by the glycoprotein patatin and various protease inhibitors, have been reported in earlier literature to rival or exceed those of legumes, and the Lafia samples appear to bear that out. The yam, however, fought back on two fronts: it contained more crude fiber, at 9.99 percent versus 8.53 percent, and more ash, at 6.29 percent versus 5.31 percent, indicating superior mineral density and dietary fiber content.

Fat was the lowest-ranking component in both tubers, at 2.99 percent for yam and 3.22 percent for potato, consistent with the general reputation of root and tuber crops as low-fat foods, though the authors note that frying can change that picture dramatically. Carbohydrate dominated everything else, with the two crops nearly tied at 63.60 percent for yam and 63.74 percent for potato. Both samples showed remarkably low moisture contents of around 5.3 to 5.5 percent, far below the 54 to 75 percent range typical of fresh tubers, a consequence of the dehydration protocol. Low moisture translates to high dry matter, which the researchers point out is a hallmark of good eating and textural quality, and it also means the flours resist microbial spoilage and store well, an important consideration for food industries.

The phytochemical results are where the story gets genuinely nuanced, because the compounds measured are double agents: some harm nutrition, others protect health. Yam contained more than twice the oxalate of potato, 6.52 percent against 2.73 percent, a difference with real consequences, since oxalates bind minerals such as calcium and iron and, at high intakes, can contribute to kidney stone formation. Yam also carried more phytate, at 333.63 milligrams per 100 grams versus 300.10 for potato. Phytate is a notorious chelator of minerals, yet the same molecule exhibits antioxidant and anticancer potential and even binds toxic heavy metals like cadmium and lead, illustrating how context determines whether a compound is villain or guardian.

Potato, meanwhile, led on several other fronts. It contained more alkaloids, 9.47 percent versus 7.37 percent, a notable finding given that alkaloid derivatives display analgesic, antitussive, and antibacterial pharmacological activities, though potato alkaloids are also the class of compounds behind greening-related toxicity when tubers are mishandled. Potato also showed higher tannins, at 3.04 milligrams per 100 grams against 2.14, and a strikingly higher cyanide content of 1.52 milligrams per 100 grams compared with just 0.42 in yam. The authors are careful to note that these cyanide levels remain well below acute toxicity thresholds, but they emphasize that neither tuber should ever be eaten raw and that adequate cooking is critical for degrading residual cyanogenic glycosides. Yam, for its part, dominated the antioxidant ledger, with flavonoids at 9.13 percent against potato’s 3.25 percent, suggesting stronger protection against oxidative stress and inflammation.

The amino acid analysis added another layer of sophistication. Glutamic acid was the most abundant amino acid in both tubers, at 12.65 grams per 100 grams of protein in potato and 9.01 in yam, followed by aspartic acid, which reached 9.87 grams in potato versus 7.60 in yam. Potato outperformed yam on most essential amino acids, including leucine, lysine, isoleucine, tryptophan, valine, methionine, and threonine, while yam held the edge in phenylalanine, proline, arginine, glycine, cystine, and alanine. Arginine is particularly interesting, as the authors note its value as a supplement during pregnancy, trauma, and illness such as cancer. Tryptophan, the sole precursor of the neurotransmitter serotonin, which regulates appetite, sleep, and mood, was also higher in potato, as was the case for the branched-chain amino acids that support muscle repair and blood sugar control.

When the researchers computed composite quality metrics, potato again came out ahead on protein. Its predicted protein efficiency ratio, calculated from leucine and tyrosine content using a classic regression equation, was 2.09 versus 1.92 for yam, and its leucine-to-isoleucine ratio of 3.08 dwarfed yam’s 1.79. Potato also scored higher on total amino acids, total non-essential amino acids, total acidic and basic amino acids, and amino acid scores for most essential residues, leading the authors to conclude that potato delivers the higher overall protein quality. Yam, by contrast, led on total essential amino acid fractions when histidine was included and on sulfur-containing amino acid parameters, underscoring just how complementary the two crops are rather than how one simply beats the other.

The authors are refreshingly candid about the limitations of their work. All measurements were performed only in duplicate, which they acknowledge was insufficient for meaningful inferential statistical comparison, meaning the compositional differences reported here cannot yet be formally tested for significance. They commit to larger replicate numbers in future studies to strengthen reproducibility. This honesty matters in a field where single-sample analyses are sometimes overinterpreted, and it frames the study as a strong, variety-specific baseline for Lafia-grown tubers rather than a definitive word on all Nigerian yams and potatoes.

The bigger picture is one of agricultural and nutritional strategy. Nigeria is the world’s leading yam producer, contributing 65.5 percent of global output, while it ranks fourth in sub-Saharan Africa for potato production with more than 1.28 million metric tonnes annually. As climate pressure and population growth strain food systems, understanding exactly what these staples deliver, and what processing can unlock, becomes a matter of public health. The researchers conclude that all antinutrient levels observed fall within ranges that standard techniques such as boiling, fermentation, soaking, and roasting can effectively minimize, and that cooking yams in particular reduces phytate while water-soluble tannins largely leach away. Their bottom line is pragmatic and encouraging: potato offers the better protein package, yam the better fiber, minerals, and antioxidants, and eaten together, properly cooked, the two tubers form a genuinely balanced dietary partnership for the hundreds of millions who depend on them.

Subject of Research: Comparative nutritional and antinutritional composition of white yam and Irish potato tubers cultivated in Lafia, Nigeria

Article Title: Comparative study of nutritive and antinutritive values of Dioscorea rotundata and Solanum tuberosum cultivated in Lafia, Nigeria

Article References: Aremu, S. O., Zando, C., Aremu, M. O., Ezekiel, E., Aliyu, Z. E., Omosebi, M. O., & Aremu, D. O. (2026). Comparative study of nutritive and antinutritive values of Dioscorea rotundata and Solanum tuberosum cultivated in Lafia, Nigeria. Discover Chemistry, 3(1), Article 473. https://doi.org/10.1007/s44371-026-00917-w

Image Credits: AI Generated

DOI: 10.1007/s44371-026-00917-w

Keywords: Dioscorea rotundata, Solanum tuberosum, white yam, Irish potato, proximate analysis, antinutritional factors, amino acid profile, phytochemicals, food security, Nigeria, protein quality, oxalate

A research team led by Lin Yuan and Min Zhu recovered seeds from juice-processing residues of hard-seeded sour pomegranates grown in Artux, Xinjiang, China, ground and defatted them, and extracted the protein using alkaline solubilization followed by isoelectric precipitation. Rather than treating the resulting crude protein as a single material, the researchers applied Osborne sequential fractionation, a century-old technique that separates plant proteins into four classes based on solubility: water-soluble albumins, salt-soluble globulins, alcohol-soluble prolamins, and alkali-soluble glutelins. The logic is simple but powerful. If each fraction behaves differently, then the crude extract is not one ingredient but a toolkit of several, each suited to different jobs in food formulation.

The first surprise came from the physical measurements. Using dynamic light scattering and folded capillary cells, the team found that particle sizes ranged dramatically, from about 777 nanometers for the prolamin fraction to nearly 1586 nanometers for albumin. Zeta potential measurements told a complementary story: the glutelin fraction carried a surface charge of −30.14 millivolts, far stronger than the weakly charged albumin, globulin, and prolamin fractions, which hovered between −3.68 and −5.75 millivolts. The researchers attributed the glutelin’s strong negative charge to alkaline extraction, which unfolds proteins and exposes ionizable groups, while the prolamin’s compact size reflected its high hydrophobic amino acid content, which favors tight intramolecular packing over hydration-driven swelling.

Surface hydrophobicity, measured with a fluorescent ANS probe, varied more than sixfold across the fractions. The prolamin fraction topped the scale at 472.62, consistent with its alcohol-soluble nature and its extraordinary hydrophobic amino acid content of 76.35 percent, while the globulin fraction sat at the bottom with a value of just 73.23. Thermal analysis by differential scanning calorimetry showed that albumin resisted initial unfolding to the highest temperature, with an onset of 145.2 degrees Celsius, while glutelin demanded the most energy to denature, with a denaturation enthalpy of 201.65 joules per gram. The team linked glutelin’s thermal robustness to disulfide-linked subunit structures resembling 11S globulins, the same architecture that stabilizes soybean storage proteins.

Spectroscopy added a molecular dimension to the picture. Fourier-transform infrared analysis of the amide I band revealed that the prolamin fraction contained the highest alpha-helix content of all samples, at 44 percent, while albumin showed the greatest beta-sheet proportion, a feature associated with strong interchain hydrogen bonding and backbone rigidity. Circular dichroism spectra confirmed that albumin, globulin, and glutelin maintained ordered conformations in solution, whereas the crude extract, with the highest random coil content at 18 percent, was the most structurally disordered. Interestingly, the prolamin’s weak circular dichroism signals despite its high fitted helix content hinted at local conformational heterogeneity, possibly arising from its abundant alanine, which favors helices, and proline, whose rigid ring restricts the polypeptide backbone.

Where the fractions truly diverged was in function. Albumin, rich in polar residues, achieved the highest solubility at 24.32 percent but the lowest oil-holding capacity at 0.41 grams per gram. The prolamin fraction flipped that relationship entirely, dissolving at a mere 1.35 percent yet binding 2.32 grams of oil per gram, a figure that exceeds the roughly 0.8 to 1.7 grams per gram reported for most commercial soy, pea, chickpea, oat, and wheat protein ingredients. Glutelin emerged as the interfacial star: despite only intermediate solubility, it produced a foaming capacity of 112 percent, beating commercial wheat and potato proteins, and the highest emulsifying activity index at 2.26 square meters per gram. The prolamin fraction, meanwhile, delivered the highest emulsion stability at 96.33 minutes, comparable to or better than soy and pea proteins.

Nutrition told a more nuanced story. The albumin fraction was the clear winner on essential amino acids, posting the highest amino acid score, essential amino acid content, and essential amino acid index at 15.24 percent, and it also showed the lowest trypsin inhibition rate at 5.08 percent. However, chemical scoring revealed that methionine was the first limiting amino acid in every fractionated sample, meaning that sulfur-containing amino acids remain the principal nutritional bottleneck for pomegranate seed protein, just as they are for many other plant protein sources. The prolamin fraction, despite its unbalanced amino acid profile dominated by alanine and proline, offered a different virtue: the highest intestinal digestibility at 21.18 percent and the lowest phytic acid content at 1.03 micromoles per gram, a combination that reduces concerns about mineral chelation.

Digestion experiments using a simulated gastrointestinal model showed that the fractions responded very differently to the journey through the gut. During the acidic gastric phase, electrostatic stabilization weakened and particles grew, with albumin swelling to 1662.83 nanometers. In the intestinal phase, charges shifted negative and aggregates partially dissociated, shrinking albumin, globulin, and glutelin particles to between 403 and 606 nanometers. Glutelin was the exception, its digestibility actually falling from 13.45 to 11.42 percent as secondary aggregation under intestinal conditions likely shielded cleavage sites from trypsin. The correlation analysis tied these behaviors together quantitatively: digestibility correlated positively with random coil content and solubility and negatively with particle size, while surface hydrophobicity tracked oil-binding and emulsion stability with coefficients reaching 0.85.

Perhaps the most forward-looking part of the study was its proteomic layer. Using data-independent acquisition mass spectrometry, the team identified roughly 3900 proteins across the five samples and found that only about 21 percent were shared by all fractions. Principal component analysis separated the samples cleanly, and differential abundance analysis revealed fraction-specific enrichment of 2S albumin-like proteins, non-specific lipid-transfer proteins, 11S globulin-like proteins, vicilin-like storage proteins, and cupin domain-containing proteins. The enrichment of lipid-transfer-related proteins in the hydrophobic fractions offers a plausible molecular explanation for their superior oil-binding and emulsion-stabilizing behavior, while the accumulation of storage globulins in glutelin aligns with its thermal resilience. The researchers were careful to note that these are annotation-based associations rather than direct functional validation.

The proteomic screen also carried a caution flag. Six potential allergenic proteins were detected, including three isoforms of the known pomegranate allergen Pun g 1, Pun g 14, and two 2S albumins, with the mass spectrometry signals showing that fractionation redistributed but did not eliminate these proteins. The authors stress that relative spectral signals do not equate to clinical allergenicity and that targeted immunological testing will be needed before any food application. Still, the overall message is striking: a by-product that the juice industry throws away by the ton contains not one but several protein ingredients, each with a distinct structural identity, functional specialty, and nutritional profile. With methionine supplementation to address the limiting amino acid and further testing in real food systems, pomegranate seed protein fractions could find roles ranging from water-dispersible beverage bases to lipid-rich emulsions and aerated foams, turning an agricultural waste stream into a molecularly understood resource for the plant protein era.

Subject of Research: Osborne fractionation and characterization of pomegranate seed protein fractions

Article Title: Osborne fractionation of pomegranate seed protein: Structural characteristics, processing properties, proteomic profiles and nutritional value

Article References: Yuan, L., Qiu, Y., Yang, J., Fang, Q., Deng, Q., Hong, J., Zhao, M., & Zhu, M. (2026). Osborne fractionation of pomegranate seed protein: Structural characteristics, processing properties, proteomic profiles and nutritional value. Food Chemistry: X, Article 104551. https://doi.org/10.1016/j.fochx.2026.104551

Image Credits: AI Generated

DOI: 10.1016/j.fochx.2026.104551

Keywords: pomegranate seed protein, Osborne fractionation, plant protein, albumin, globulin, prolamin, glutelin, proteomics, food chemistry, in vitro digestion, amino acid profile, sustainable food ingredients