A research team led by Tingchen Si and colleagues, publishing in Food Chemistry: X, has now systematically tested two contrasting pretreatment strategies to solve this dilemma: steam explosion and heat curing. Their goal was ambitious. Rather than simply stabilizing the mushroom powder, they wanted to know whether these treatments could actively upgrade it, enhancing flavor, refining particle structure, and improving compatibility with wheat dough so that the powder could be folded into noodles without wrecking the gluten network. The work combined electronic nose profiling, gas chromatography-ion mobility spectrometry, free amino acid quantification, infrared spectroscopy, particle size analysis, electron microscopy, and a battery of dough rheology tests, offering one of the most complete pictures yet of how processing reshapes a functional mushroom ingredient.

Steam explosion is a dramatic technique by any standard. Dried mushroom pieces were rehydrated for twelve hours, then loaded into a pressurized chamber where saturated steam at 0.6, 0.9, or 1.2 megapascals was held for five minutes before an abrupt release of pressure. In that instant, stored thermal energy converts into mechanical energy, tearing apart cell walls and fibrous architecture. Heat curing took a gentler path: ground mushroom powder spread in thin layers was heated at 90, 100, 110, or 120 degrees Celsius for fifteen minutes each. The two methods thus represent opposite philosophies, one delivering a violent mechanical shock in seconds, the other applying controlled, sustained heat.

The amino acid results were striking. Steam explosion at 0.9 megapascals more than doubled total free amino acids, raising them from 26.54 milligrams per gram in untreated powder to 66.89 milligrams per gram. Umami amino acids such as glutamic and aspartic acid, the molecular backbone of savory taste, nearly doubled, while sweet amino acids climbed almost threefold. The mechanism is physical as much as chemical: the pressure release disrupts intracellular matrices and releases pre-existing free amino acids, while high-temperature, high-pressure conditions denature proteins, unfold peptide chains, and weaken non-covalent interactions, making proteins vulnerable to degradation into smaller nitrogenous compounds. Crucially, the short residence time limits the Maillard reaction, so amino acids are liberated faster than they are consumed. Pressure mattered enormously. At 0.6 megapascals the disruption was insufficient; at 1.2 megapascals excessive thermal exposure drove secondary degradation, reducing net accumulation. The 0.9 megapascal condition hit the sweet spot.

Heat curing told a different story. At 90 degrees Celsius, total free amino acids rose modestly to 29.92 milligrams per gram, but every additional ten degrees pushed them sharply downward, falling to just 13.02 milligrams per gram at 120 degrees. The culprit is the Maillard reaction, which accelerates at higher temperatures as amino acids react with reducing sugars to form melanoidins and heterocyclic compounds, consuming precisely the umami amino acids that give mushrooms their appeal. Prolonged high heat can also trigger deamidation and oxidative degradation of asparagine and glutamine, while cellular autolysis activates endogenous proteases that further erode the free amino acid pool. The lesson is that heat curing rewards restraint: gentle temperatures preserve, aggressive ones destroy.

Aroma analysis revealed equally distinctive fingerprints. Gas chromatography-ion mobility spectrometry detected 106 volatile organic compounds across the samples, including 17 esters, 15 aldehydes, 14 alcohols, 11 ketones, and 6 pyrazines. Untreated powder retained a natural, plant-like profile dominated by pentanal, octanal, and ethyl acetate, with fruity and green notes. Heat-cured powder developed elevated concentrations of butanal, 3-methylbutanal, and various esters, producing sweet, chocolate-like fruity aromas alongside pungent sulfides. Steam-exploded powder underwent the most dramatic transformation: high-temperature, high-pressure conditions promoted Maillard chemistry, generating roasted, nutty pyrazines such as 2-ethyl-3-methylpyrazine alongside characteristic mushroom ketones like 1-octen-3-one. Principal component analysis confirmed that the volatile profiles of the treated and untreated powders were clearly separable, with the first two components explaining 94 percent of the variance.

Structural measurements reinforced why these powders behave differently in dough. Steam-exploded powder had the smallest median particle size, at 136.96 micrometers compared with 187.99 micrometers for untreated powder, because the instantaneous pressure release shatters cell walls and fibrous networks into finer fragments. Scanning electron microscopy showed the steam-exploded particles with loosened, disrupted microstructure and smoother surfaces, while untreated and heat-cured powders displayed wrinkled, compact, rough textures. Fourier transform infrared spectroscopy, meanwhile, showed that the fundamental functional groups, including hydroxyl stretches near 3432 per centimeter and carbonyl bands near 1640 per centimeter, were broadly retained across all treatments, meaning the chemical identity of the mushroom matrix survived even as its physical architecture was rebuilt.

The decisive test came when the powders were blended into wheat flour at substitution levels of 1, 3, 5, and 7 percent. Mixolab thermomechanical analysis showed that untreated mushroom powder steadily degraded dough performance, cutting stability time from 7.95 minutes to 3.60 minutes at 7 percent substitution as the dilution of gluten-forming proteins weakened the cohesive network. Steam-exploded powder behaved remarkably differently: stability time barely changed, holding at 7.35 minutes even at 7 percent substitution, apparently because the modified fiber and polysaccharide components disperse well within the gluten-starch matrix and interact constructively with gluten proteins. Water absorption rose in all formulations, reflecting the mushroom powder’s strong water-holding capacity, but the processed powders demanded less added water than the untreated one. The 5 percent substitution level emerged as the optimal balance, enhancing functional contribution while preserving gluten network integrity.

Rheological and pasting measurements added further nuance. All composite doughs exhibited elastic-dominant viscoelastic behavior, with storage modulus exceeding loss modulus across the tested frequency range and loss tangent values below one, indicating solid-like structures suitable for noodle processing. Rapid Visco Analyzer results showed that peak viscosity declined with mushroom addition, most sharply for heat-cured powder, whose water-hungry fiber competes with starch for moisture and restricts granule swelling. Steam-exploded powder, by contrast, released soluble polysaccharides that partially compensated for this restriction, keeping peak viscosity statistically indistinguishable from the control. Setback values, which track starch retrogradation during cooling and predict staling, fell in all mushroom-supplemented samples, suggesting the treated powders could help noodles stay fresher longer.

Low-field nuclear magnetic resonance provided the final piece of the puzzle by tracking water mobility inside the dough. All samples showed three proton populations corresponding to bound, partially immobilized, and free water, but the steam-exploded and heat-cured formulations shifted the transverse relaxation times of the immobilized water fraction to longer values, indicating increased water mobility and weaker water-matrix interactions. This redistribution, likely tied to the porous microstructure of the treated fibers, can improve gluten hydration and dough softness while influencing starch retrogradation. Taken together, the findings sketch a practical decision framework for food manufacturers: steam-exploded powder at 0.9 megapascals suits flavor-focused, high-dispersibility applications such as noodles, while 90-degree heat-cured powder, with its enhanced sweet aroma compounds and preserved organic acids, fits bakery and steamed bread products where elasticity and aroma matter most. Both routes turn a perishable, flavor-fragile mushroom into a stable, functional ingredient, and both leave the gluten network largely intact at moderate substitution levels, bringing wine-cap mushroom noodles a significant step closer to the supermarket shelf.

Subject of Research: Effects of steam explosion and heat curing pretreatments on the physicochemical properties of Stropharia rugosoannulata powder and wheat dough quality

Article Title: Effects of steam explosion and heat curing on the physicochemical properties of Stropharia rugosoannulata powder and dough quality

Article References: Si, T., Arshad, A., Intizar, A., Rong, Q., Liu, S., Sun, Y., Li, X., Gao, K., & Liang, J. (2026). Effects of steam explosion and heat curing on the physicochemical properties of Stropharia rugosoannulata powder and dough quality. Food Chemistry: X, 39, Article 104502. https://doi.org/10.1016/j.fochx.2026.104502

Image Credits: AI Generated

DOI: 10.1016/j.fochx.2026.104502

Keywords: wine-cap mushroom, Stropharia rugosoannulata, steam explosion, heat curing, free amino acids, umami, flavor compounds, dough rheology, noodles, dietary fiber, LF-NMR, food processing