The research, led by Patricia Rodríguez-Castillo and colleagues at Tecnológico de Monterrey, tackles a fundamental problem in food chemistry. In cereal and pseudocereal grains, many phenolic compounds are not freely floating in the cell interior. Instead, they are esterified or otherwise bound to cell-wall polymers and other macromolecular structures. This bound fraction can represent a large share of the total phenolic pool, and unless the matrix is physically disrupted, standard solvent extraction simply cannot reach it. Hydroxycinnamic acid derivatives of genuine nutritional significance may remain locked inside structural fractions, leading analysts to underestimate the true antioxidant wealth of the seed.

DIC offers a strikingly elegant solution. The process works like a controlled steam explosion: amaranth grains are loaded into a reactor, a preliminary vacuum is drawn, and dry saturated steam is injected until a target pressure is reached. After a precisely timed hold, the pressure is dropped almost instantaneously toward a deep vacuum, at rates exceeding 0.5 megapascals per second. This sudden decompression forces the moisture inside the grain to flash-evaporate, cooling the material instantly while simultaneously causing it to expand and develop a sponge-like network of microstructural alveoli. The resulting porous architecture makes it far easier for solvents to penetrate the matrix and leach out compounds that were previously physically entrapped within the cell-wall network.

To test how these thermomechanical forces translate into chemical changes, the team worked with two Mexican subvarieties of A. hypochondriacus, Laura and Criollo, from the 2023 harvest in Puebla. They designed a rigorous central composite experiment spanning thirteen treatment combinations, with steam pressure ranging from 0.10 to 0.40 megapascals and processing times from 10 to 90 seconds. Treated and untreated grains were then ground, extracted with ethanol, and analyzed by high-performance liquid chromatography to quantify individual phenolic compounds, while the lipid fraction was characterized by gas chromatography-mass spectrometry.

The results for the Criollo variety were remarkable. Total quantified phenolics ranged from a low of 346.14 micrograms per gram under mild conditions to a striking 3035.2 micrograms per gram at moderate settings of 0.25 megapascals and 50 seconds, a condition that more than tripled the untreated control’s 828.38 micrograms per gram. Catechin emerged as the dominant compound in every sample, soaring from 679 micrograms per gram in the control to as much as 2704 micrograms per gram after treatment. Rutin, quercetin, gallic acid, and trans-4-hydroxycinnamic acid all showed statistically significant increases across most treatments, and the most favorable conditions also produced the widest diversity of detected compounds, with seven of eight identified peaks appearing in the chromatograms.

The Laura variety told a more nuanced story, one that underscores how sensitive these responses are to both genetics and processing intensity. Here, the same moderate condition of 0.25 megapascals for 50 seconds again delivered the highest phenolic concentration at 2074.15 micrograms per gram, though this did not differ significantly from the untreated grain. More revealing was what happened under harsher treatment: at 0.36 megapascals for 78 seconds, total phenolics collapsed to just 281.51 micrograms per gram and only three of ten peaks remained detectable. The contrast between this sample and DIC 6, which shared the same pressure but ran for only 22 seconds and displayed nine peaks, suggests that prolonged exposure to high-pressure steam can actively degrade delicate bioactive compounds rather than merely failing to release them.

Response surface modeling and Pareto analysis confirmed these patterns statistically, showing that moderate to high pressure combined with moderate time frames consistently maximized phenolic recovery, while quadratic terms in the fitted equations captured the penalty for pushing conditions too far. The findings align with earlier work by the same group showing improved antioxidant capacity in DIC-treated amaranth, as well as studies on green lentils, grape pomace, and oleaster flour, all of which reported enhanced polyphenol extractability following thermomechanical texturing. Together they paint a coherent picture: the sweet spot lies in enough mechanical disruption to fracture cell walls, but not so much thermal load that phenolics break down.

Crucially, the team also asked whether this violent process damages the lipid fraction, a legitimate concern given that unsaturated fatty acids and minor lipids like squalene are notoriously vulnerable to oxidation and heat. The answer was reassuring. Gas chromatography-mass spectrometry confirmed that amaranth oil remained dominated by nutritionally favorable components: in Criollo, oleic acid accounted for roughly 27 percent, linoleic acid 21 percent, palmitic acid 11 percent, and squalene an impressive 26 percent of the oil. Laura showed a similar pattern with 24 percent oleic, 25 percent linoleic, 20 percent palmitic, and 19 percent squalene. Saturated fatty acids made up only 22 to 30 percent of the total, preserving the grain’s balanced lipid signature.

Squalene deserves particular attention here. This triterpenoid, found in significant quantities in amaranth oil, exhibits documented antioxidant, anti-inflammatory, hepatoprotective, and cardioprotective activities, and it is one of the main reasons amaranth oil commands interest beyond basic nutrition. The study found that processing parameters did influence the relative proportions of specific fatty acids, with lower pressures and longer times favoring higher linoleic acid percentages in Criollo, and lower pressures boosting squalene in Laura, while oleic acid remained largely indifferent to the treatments. Some minor saturated fatty acids, including stearic and arachidic acid, disappeared from certain treatments, echoing similar observations in DIC-processed cardamom seeds and hinting at selective effects on less abundant lipid species.

The broader implications are compelling for the functional food industry. Amaranth’s phytochemical profile, spanning hydroxybenzoic acids, hydroxycinnamic acids, and flavonoids related to quercetin and kaempferol, varies considerably with species, genotype, and growing conditions, which has long complicated its use as a standardized ingredient. This study demonstrates that DIC is not merely a passive processing step but a tunable dial: by adjusting steam pressure and exposure time, manufacturers can deliberately modulate which compounds become extractable and in what quantities, all within processing windows measured in seconds rather than minutes. The fact that catechin remained dominant across all treatments indicates that DIC primarily shifts availability and relative distribution rather than eliminating key constituents. As demand grows for nutrient-dense, plant-based ingredients with verified bioactive content, the image of amaranth grains exploding into porous, antioxidant-rich flour inside a steel reactor may become a familiar sight, bridging five centuries of agricultural heritage with some of the most sophisticated food engineering available today.

Subject of Research: Effect of Instant Controlled Pressure Drop processing on phenolic compounds and fatty acids in amaranth grain

Article Title: Instant Controlled Pressure Drop Processing Modulates Phenolic Composition and Fatty Acid Profile in Amaranthus hypochondriacus Grain.

Article References: Rodríguez-Castillo, P., Teresa-Martínez, G., Alonzo-Macías, M., Téllez-Pérez, C., & Cardador-Martínez, A. (2026). Instant Controlled Pressure Drop Processing Modulates Phenolic Composition and Fatty Acid Profile in Amaranthus hypochondriacus Grain.. Current Research in Food Science, Article 101576. https://doi.org/10.1016/j.crfs.2026.101576

Image Credits: AI Generated

DOI: 10.1016/j.crfs.2026.101576

Keywords: amaranth, Instant Controlled Pressure Drop, phenolic compounds, fatty acids, squalene, catechin, functional foods, HPLC, GC-MS, pseudocereal, antioxidants, food processing

The rationale is rooted in plant stress physiology. When leafy vegetables are exposed to short-term abiotic stresses such as UVB radiation in the 290 to 315 nanometer range, they respond by activating defense-related secondary metabolism, particularly the phenylpropanoid pathway that generates phenolic acids and flavonoids. Previous work by the same group demonstrated that a seven-minute UVB exposure at a dose of 5.04 kilojoules per square meter maximized phenolic content, cellular antioxidant activity, and anti-inflammatory potential in fresh amaranth leaves. The new study asked whether that bioactive boost could survive dehydration, milling, incorporation into masa, and a scorching 280 to 300 degree Celsius bake.

To scale the concept beyond the laboratory, the team built an industrial-design-registered irradiation chamber fitted with twelve 40-watt broadband UVB lamps, increasing per-lamp power 4.3-fold and total system power 8.7-fold over an earlier prototype. Fresh leaves of Amaranthus hybridus var. Negra 1, harvested 42 days after sowing at the university’s experimental farm in Querétaro, were laid in a single layer, irradiated for seven minutes, rested for five, then dried in a solar dehydrator at 65 degrees Celsius for seven hours and milled into powder. A parallel untreated batch yielded the control powder. Rheological screening with a Mixolab instrument then identified 7.5 percent substitution on a dry-weight basis as the highest level that preserved measurable dough behavior and acceptable tortilla quality.

Nutritionally, the fortification paid off. Control maize tortillas contained 8.80 percent protein and 1.52 percent ash on a dry-weight basis, while tortillas with untreated amaranth powder reached 10.16 percent protein and 3.32 percent ash, and those with UVB-treated powder hit 10.48 percent and 3.35 percent, respectively. Total dietary fiber rose from roughly 3.0 percent to about 4.8 percent, and total starch fell from about 76.6 percent to about 71.0 percent. The researchers caution that the higher ash in the UVB powder likely reflects a relative concentration effect, since ultraviolet light cannot introduce minerals, but the protein and fiber gains in the final tortillas are unambiguous contributions of the leaf ingredient.

Perhaps the most striking nutritional result concerns starch digestibility. Rapidly digestible starch, the fraction most quickly converted to glucose, plummeted from 85.29 percent in fresh control tortillas to 54.33 percent and 56.02 percent in the amaranth-enriched versions after five days of refrigerated storage, while slowly digestible starch climbed. The predicted glycemic index dropped by roughly 9 to 13 units compared with the control, falling from 92.60 to 79.92 by day five. The authors attribute this to a combination of reduced total starch, a physical barrier effect from dietary fiber, and non-covalent interactions between phenolic compounds and starch or digestive enzymes that slow enzymatic hydrolysis. Although the values remain in the high glycemic range, the researchers describe the shift as a relevant improvement for a staple food.

Equally important, the treatment improved rather than worsened the anti-nutritional profile. UVB exposure reduced oxalates by 28.8 percent, nitrates by 33.7 percent, phytic acid by 25.2 percent, saponins by 26.7 percent, tannins by 19.4 percent, and protease inhibitors by 44.3 percent in the powder. After dilution into tortillas and thermal processing, anti-nutrient concentrations fell further, and the authors estimate that even a daily intake of six tortillas, about 144 grams, would keep these compounds below levels of nutritional concern. Microbiological testing after one week of refrigerated storage confirmed compliance with the Mexican standard NOM-187-SSA1-SCFI-2002, with total aerobic mesophiles and molds and yeasts below 10 colony-forming units per gram.

The phenolic chemistry revealed a subtler story than a simple boost. Using UPLC-MS/MS with 65 authentic standards, the team quantified 22 phenolic compounds plus L-phenylalanine, the entry substrate of the phenylpropanoid pathway. UVB treatment raised L-phenylalanine by 23 percent, consistent with stress-primed metabolism, and selectively increased salicylic acid by 282 percent, 4-hydroxybenzoic acid by 96 percent, and 4-hydroxyphenylacetic acid by 69 percent, while several hydroxycinnamic and benzoic acids declined. Crucially, the total quantified phenolics in the powder actually fell by 16.7 percent, yet the tortillas made with UVB-treated powder emerged with the richest phenolic profile of all: 5.519 micrograms per gram, 3.29 times more than tortillas with untreated powder and 2.11 times more than the maize control. Rutin alone was 10.5-fold higher in the UVB-powder tortillas than in the untreated-powder version.

Because rutin levels were nearly identical in both powders, the authors argue that this enrichment arose during dough mixing and baking, not from new biosynthesis during the brief irradiation. They propose that UVB-induced changes to the leaf matrix, including altered extractability, photochemical transformation of pre-existing compounds, or differential thermal stability during baking, favored the retention of specific flavonoids. The team is careful to note that the seven-minute exposure plus five-minute rest is too short for measurable phenylalanine ammonia-lyase-mediated synthesis, and that without gene expression or time-resolved profiling data, mechanistic claims remain plausible hypotheses rather than proven pathways.

The functional assays translated the chemistry into cell-level biology. Extracts from the UVB-powder tortillas inhibited nitric oxide production in lipopolysaccharide-stimulated RAW 264.7 macrophages by 67.52 percent, roughly 2.4 times the control’s 27.87 percent and 1.6 times the untreated-powder tortillas’ 42.39 percent. Cellular antioxidant activity in Caco-2 intestinal cells reached 72.67 percent, an 85 percent increase over the control’s 39.29 percent. MTT assays confirmed the extracts were not cytotoxic. The authors link these effects to the enriched rutin, protocatechuic acid, caffeic acid, and salicylic acid content, while acknowledging that amaranth proteins and fiber may also contribute independently.

Consumers, however, rendered a more tempered verdict. In a 40-person sensory panel using a seven-point hedonic scale, control tortillas scored 5.55 for overall acceptability, while the UVB-powder tortillas scored 4.38, close to neutral, with no significant penalty relative to untreated-powder tortillas. Seventy percent of participants preferred the plain maize version. The darker green-brown color and possible bitter phenolic notes explain the trade-off, and the authors suggest particle-size optimization, flavor masking, or debittering strategies as next steps. Even so, the study demonstrates that a culturally familiar staple can be upgraded with more protein, fiber, and bioactivity, a lower glycemic signature, and no added anti-nutritional burden, all through a seven-minute dose of light. The researchers emphasize that in vitro results must now be followed by bioaccessibility, bioavailability, and in vivo studies before health claims can be made, but the proof of concept for postharvest UVB biofortification of tortillas stands.

Subject of Research: Postharvest UVB biofortification of amaranth leaf powder as a functional ingredient in nixtamalized maize tortillas

Article Title: Postharvest UVB treatment of amaranth leaves produces a bioactive powder ingredient that improves the phenolic signature and bioactivity of nixtamalized maize tortillas

Article References: Segura-Jiménez, M. E., de la Rosa-Millán, J., Antunes-Ricardo, M., Sánchez-Reséndiz, A. I., Gastélum-Estrada, A., Guerrero-Analco, J. A., Monribot-Villanueva, J. L., Valencia-Mejía, E., Pérez-Carrillo, E., & Jacobo-Velázquez, D. A. (2026). Postharvest UVB treatment of amaranth leaves produces a bioactive powder ingredient that improves the phenolic signature and bioactivity of nixtamalized maize tortillas. Journal of Agriculture and Food Research, 31, Article 103315. https://doi.org/10.1016/j.jafr.2026.103315

Image Credits: AI Generated

DOI: 10.1016/j.jafr.2026.103315

Keywords: amaranth, UVB radiation, tortillas, nixtamalization, phenolic compounds, rutin, antioxidant activity, anti-inflammatory, glycemic index, functional foods, postharvest biofortification, maize

The research team focused on two cultivars with very different personalities: A. tricolor L. cv. Valentina, a red-leaved variety, and A. cruentus L. cv. Krepysh, a green-leaved type. Plants were grown outdoors at the Federal Horticultural Research Center for Breeding, Agrotechnology and Nursery in Moscow across the 2020–2021 seasons, with drought imposed after two months of growth by withholding water until substrate humidity fell to 20–25 percent, a condition maintained for seven days before sampling. Ten biological and ten technical replicates per treatment gave the researchers a statistically robust foundation for comparing stressed and well-watered leaves.

What they found was a dramatic metabolic reprogramming. In the leaves of cv. Valentina, drought triggered an approximately 70-fold surge in mannonic acid, a 40-fold rise in myo-inositol, a 23-fold increase in caffeic acid, a 15-fold jump in tartaric acid, and a seven-fold elevation of glycerol. The amino acids L-proline and serine climbed four-fold, while glycolic, oxalic, and lactic acids rose two to three times. These molecules are classic osmoprotectants and compatible solutes: by accumulating inside cells, they lower osmotic potential, helping leaves retain turgor and water even as the soil dries out around their roots.

Each of these metabolites plays a distinct protective role. Myo-inositol, for instance, is far more than a simple osmolyte; it is a core precursor in the phosphoinositide signaling pathway, which mediates intracellular signal transduction and orchestrates the downstream transcriptional activation of drought-responsive genes. Caffeic acid, a key intermediate in the phenylpropanoid pathway, boosts the plant’s non-enzymatic antioxidant capacity by scavenging the reactive oxygen species that accumulate when drought inhibits photosynthesis, thereby preventing lipid peroxidation and cellular damage. Flavonoids such as apigenin add another layer of defense, neutralizing ROS and maintaining cellular redox homeostasis.

In total, the team annotated 41 distinct substances across the leaf extracts, with 40 detected in cv. Krepysh and 34 in cv. Valentina. Nine of these compounds carry documented antimicrobial properties, including lactic, pyruvic, glyoxylic, malic, acrylic, and tartaric acids, along with glycerol, acetamide, and benzoic acid. Under baseline conditions, lactic, benzoic, malic, and mannonic acids were 40, 6, 2, and 1.5 times more abundant, respectively, in cv. Valentina than in cv. Krepysh. Glyoxylic acid appeared exclusively in the green-leaved cultivar, while acetamide was unique to the red-leaved one, underscoring the distinct biochemical identities of the two varieties.

Yet the study’s most provocative contribution lies not in the biology but in the analytical chemistry. Conventional high-throughput metabolomics suffers from a sobering limitation: typically only 5 to 15 percent of the spectral features in a complex mass spectrometry dataset can be unambiguously assigned using existing database-searching algorithms. Incomplete derivatization, analyte degradation, matrix effects, and co-eluting metabolites all conspire to blur the picture. Structurally similar compounds and stereoisomers often produce virtually identical mass spectra, and library matching scores below 750 or correlation coefficients under 0.98 leave annotators guessing, with real risks of structural misidentification.

To break through this bottleneck, the authors deployed a framework they call stochastic dynamics mass spectrometry, or SD-MS. Rather than treating mass spectra as static fingerprints to be matched against libraries, SD-MS models ion fragmentation and peak formation as stochastic processes governed by the electronic structures, ground-state energies, and vibrational frequencies of isolated ionic species. The mathematical equations link experimental measurands such as mass-to-charge ratios and ion peak intensities directly to intrinsic molecular properties and three-dimensional structural parameters, explicitly accounting for the random fluctuations and signal variances that conventional deterministic models ignore.

The framework proved its mettle on notoriously difficult cases. Fumaric acid, for example, yielded a low library score of 710 that could not distinguish its E- and Z-isomers, yet SD-MS correlation analysis achieved coefficients as high as 0.9965 for the E-isomer by comparing theoretical ion intensities with experimental data. For the flavonoid apigenin, whose spectrum is nearly indistinguishable from its structural isomer genistein, the method delivered a correlation of 0.99977, clearly separating the two. Silylated dicarboxylic acids and even bulky synthetic fluorinated derivatives of trifluoroacetic acid reached correlations up to 0.99985, far exceeding the performance of standard omics-matching algorithms.

The quantum-chemical engine behind these calculations relied on density functional theory with the hybrid meta-GGA M06-2× functional and basis sets including SDD, LANL2DZ, and aug-cc-pVDZ, executed in Gaussian, Dalton, and GAMESS-US packages. Geometry optimizations, transition-state validations, and Born–Oppenheimer molecular dynamics simulations provided the theoretical ion intensities that were then cross-correlated with experimental measurements using rigorous chemometrics, including Shapiro–Wilk normality tests and two-way ANOVA to account for random error sources across scan intervals.

Beyond the technical triumph, the work carries real agricultural weight. The enriched antioxidant and nutraceutical profile of cv. Valentina, with its superior adaptive potential under water deficit, marks it as a promising genetic source for breeding programs aimed at climate-resilient crops. By identifying specific biochemical markers of drought tolerance and pairing them with an analytical tool capable of definitive three-dimensional molecular identification, the study offers both a blueprint for understanding plant resilience and a practical foundation for engineering or breeding the drought-proof vegetables of the future.

Subject of Research: Drought-induced metabolite profiling of Amaranthus tricolor and Amaranthus cruentus leaves by GC–MS and stochastic dynamics mass spectrometry

Article Title: Gas chromatography–mass spectrometry molecular structural analysis of Amaranth leaf metabolites under drought stress

Article References: Feng, J., Gins, E., Ivanova, B., Motyleva, S., Gins, V., Gins, M., & Zhang, H. (2026). Gas chromatography–mass spectrometry molecular structural analysis of Amaranth leaf metabolites under drought stress. Results in Chemistry, 30, Article 103816. https://doi.org/10.1016/j.rechem.2026.103816

Image Credits: AI Generated

DOI: 10.1016/j.rechem.2026.103816

Keywords: amaranth, drought stress, metabolomics, gas chromatography–mass spectrometry, stochastic dynamics mass spectrometry, osmoprotectants, antioxidants, myo-inositol, caffeic acid, apigenin, quantum chemistry, plant resilience