Flavoromics maps the volatile ticking clock of a stored wine cap mushroom

Fresh wine cap mushrooms, known scientifically as Stropharia rugosoannulata, begin to lose their quality the moment they are harvested, and a new study has now charted that decline in extraordinary chemical detail. Researchers in China tracked the mushroom over ten days of cold storage at 5 degrees Celsius, combining measurements of weight, texture and color with an advanced two-dimensional gas chromatography technique that separates and identifies volatile compounds with exceptional resolution. Their analysis detected 9,746 volatile compounds across the storage period and revealed a predictable chemical succession: an alcohol-dominated profile in fresh mushrooms gives way to an ester-enriched one in mid-storage, and finally to a profile dominated by lipid oxidation products as the tissue senesces.

The work, published as an open access article in the journal Agricultural Products Processing and Storage, was led by Wanchao Chen, Junying Zhu and colleagues. The team harvested fruiting bodies of the Huqiu No. 5 variety at commercial maturity from a planting base in Shanghai in May 2025, transported them to the laboratory within two hours under refrigeration, and divided them into six groups corresponding to storage days 0, 2, 4, 6, 8 and 10. Each time point included four biological replicates of roughly 150 grams each, held at 5 plus or minus 1 degree Celsius and 85 plus or minus 5 percent relative humidity in darkness. Samples withdrawn at each point were split between quality measurements and volatile analysis, with the latter frozen in liquid nitrogen and stored at minus 80 degrees Celsius to prevent further enzymatic change.

The physical measurements told a story of steady decline with telling nuances. Weight loss rose progressively, from 0.33 percent after two days to 0.85 percent by day 8, then jumped to 1.22 percent at day 10, a 3.7-fold increase over the day 2 value. The authors attribute this late acceleration to progressive deterioration of cellular membranes, which lose their compartmentalization and allow unregulated water efflux. Texture followed a biphasic pattern: hardness first increased significantly from 684.57 grams at day 0 to 725.08 grams at day 2, a 5.9 percent rise the researchers link to tissue fibrosis and lignification, and then fell progressively to 563.73 grams by day 10, a 17.7 percent decrease from the starting value. Softening plateaued in the final stage, with no significant difference between days 8 and 10.

Color changes proved to be the most sensitive early warning. Lightness values held steady through day 8 before dropping sharply to 37.08 at day 10, while redness climbed continuously from 7.92 at day 0 to 16.67 at day 10 and yellowness surged sixteen-fold from 2.00 to 31.92 by day 8 before easing to 24.50. The browning index, which integrates all three color parameters, rose from 17.11 at day 0 to 144.72 at day 10, an 8.5-fold increase with near-exponential character, including an 85 percent jump during the day 4 to 6 interval. The authors interpret this continuous browning as evidence of polyphenol oxidase and peroxidase enzymes oxidizing phenolic substrates once harvest-induced cellular disruption brings them into contact, and they note that browning initiation at day 4 preceded accelerated softening and weight loss, suggesting enzymatic oxidation is among the earliest detectable deterioration events.

On the volatile side, the analytical platform was comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry, preceded by headspace solid-phase microextraction. This combination offers substantially greater separation capacity, peak resolution and sensitivity than conventional one-dimensional gas chromatography-mass spectrometry, allowing the researchers to resolve co-eluting compounds through software deconvolution and identify them by matching mass spectra against the NIST 20 and Wiley 9 libraries together with retention index calculations. The total number of detected volatiles rose from 3,532 at day 0 to a maximum of 4,193 at day 10, an 18.7 percent increase, with a biphasic trajectory: a rapid rise from day 0 to day 2, a slight dip at day 4, then a steady climb through day 10. The authors suggest this reflects an initial burst of volatile production after harvest stress, a temporary metabolic equilibration, and then sustained generation as degradation processes intensify.

Class-level composition shifted in lockstep. Alcohols dominated the fresh profile at 23.44 percent of total volatile content at day 0 but declined steadily to 16.22 percent by day 10, even though the number of alcohol compounds stayed relatively stable between 248 and 279, indicating their quantitative importance faded while their diversity persisted. Esters showed the most dramatic swings, surging from 14.36 percent at day 0 to 24.40 percent at day 4, roughly a 70 percent increase, before settling at 21.58 percent by day 10, with compound numbers peaking at 293 on day 6. Ketones dipped from 16.42 percent at day 0 to 8.82 percent at day 4 and then rebounded to 18.48 percent by day 8, a pattern the authors attribute to the early decline of freshness-related ketones and the late accumulation of oxidation-derived ones. Hydrocarbons and organoheterocyclic compounds remained comparatively stable throughout.

To connect chemistry with perception, the team calculated relative odor activity values, a normalized measure of how strongly each compound contributes to aroma, using odor thresholds from the FlavorDB and PubChem databases. Of 223 volatiles successfully annotated with thresholds and sensory descriptors, 11 emerged as key odor-active compounds with ROAV above 1. In the early days the flavor profile was dominated by mushroom-like and fresh notes, with 1-octen-3-one, a key contributor to the mushroom’s intrinsic aroma, showing high ROAVs initially before dissipating significantly in later storage. Compounds such as 2-undecanone, described as fresh and green, and 2,3-butanedione, described as buttery, peaked at day 4. From day 6 onward, fatty and rancid notes took over as aliphatic aldehydes including heptanal, (E)-2-octenal and (E)-2-dodecenal accumulated, a shift the researchers attribute to membrane lipid peroxidation mediated by the lipoxygenase pathway. The late appearance of 3-methyl-butanoic acid, described as putrid and sweaty, hints at advanced amino acid degradation, potentially linked to spoilage microorganisms.

The correlation analysis tied these chemical shifts to the visible decay. A strong positive correlation of 0.96 emerged between the lipid oxidation product (E)-2-dodecenal and the amino acid derivative 2-methyl-butanal, while the early-stage compound 2-pentyl-furan was significantly negatively correlated with the late-stage aldehyde (E)-2-octenal at minus 0.82. Mantel testing identified moderate association trends between volatile modules and physical attributes: the browning index showed a distinct association with heptanal, and declines in hardness alongside increases in weight loss showed moderate links with (E)-2-dodecenal, 2-methyl-butanal and 3-methyl-butanoic acid. The authors frame both enzymatic browning and aldehyde generation as coupled oxidative stress responses triggered by the loss of cellular compartmentalization, and they suggest these relationships provide a theoretical basis for using volatile compounds to predict macroscopic shelf-life.

Multivariate statistics then imposed order on the ten-day trajectory. Principal component analysis of a filtered dataset of 2,375 components revealed that the samples did not drift uniformly but clustered into three distinct physiological stages: days 0 and 2 as a fresh stage, days 4 and 6 as a transitional stage of rapid metabolic shift and structural softening, and days 8 and 10 as a severe deterioration and senescence stage. A supervised partial least squares discriminant analysis achieved complete spatial separation among the three stages, with a cumulative R-squared Y of 0.9540 and a cumulative Q-squared of 0.8413, and a 200-iteration permutation test yielded a strictly negative Q-squared intercept, which the authors present as statistical evidence against overfitting. Applying a triple-filter criterion of variable importance in projection above 1, a 95 percent jackknife confidence interval lower limit above 1, and a false discovery rate adjusted P below 0.05, they isolated robust discriminant markers dominated by long-chain ketones such as 6-tridecanone and 2-heptadecanone, alongside esters and complex cyclic and aromatic compounds.

The final layer of analysis identified progressive markers of aging. Volcano plot comparisons showed 344 compounds significantly upregulated and 203 downregulated in the transition from stage one to stage two, and 357 upregulated against 232 downregulated from stage two to stage three, a pattern the authors read as evidence that flavor deterioration is an active, senescence-driven biochemical process rather than a passive fading of fresh aromas. Intersecting these univariate results with the multivariate screen yielded seven compounds that rose continuously across all stage comparisons: n-caprylic acid isobutyl ester, 2-(4-methoxyphenyl)ethanol, 1-hexyl-cyclopentene, 2-heptadecanone, 3-(4-methoxyphenyl)propionic acid ethyl ester, methoxyacetic acid hexyl ester and butanedioic acid diethyl ester. A single compound, 3-ethenyl-pyridine, declined continuously. The authors describe these eight core biomarkers as molecular ticking clocks whose progressive trends across all six time points make them candidates for real-time freshness assessment and shelf-life prediction in cold chain logistics, while noting that future work should validate them across different cultivars and storage conditions and explore their biosynthetic pathways.

Subject of Research: Volatile compound dynamics and quality deterioration of Stropharia rugosoannulata mushrooms during cold storage

Article Title: Data-driven flavoromics reveals postharvest quality deterioration and volatile compound dynamics in Stropharia rugosoannulata mushroom during cold storage

Article References: Chen, W., Zhu, J., Li, W., Wu, D., Zhang, Z., Liu, P., & Yang, Y. (2026). Data-driven flavoromics reveals postharvest quality deterioration and volatile compound dynamics in Stropharia rugosoannulata mushroom during cold storage. Agricultural Products Processing and Storage, 2(1), Article 44. https://doi.org/10.1007/s44462-026-00078-0

Image Credits: AI Generated

DOI: 10.1007/s44462-026-00078-0

Keywords: Stropharia rugosoannulata, wine cap mushroom, flavoromics, postharvest quality, volatile organic compounds, GC×GC-TOF MS, cold storage, browning index, lipid oxidation, odor activity value, biomarkers, shelf-life