Yeast autolysis influences both wine composition and sensory properties, particularly when lees contact is encouraged. This study applied ATR-FTIR microspectroscopy with multivariate analysis to monitor autolytic processes in several Saccharomyces strains.The technique successfully distinguished S. cerevisiae EC 1118 and FR-B from CH, as well as S. bayanus Q20, based on autolysis kinetics involving mannans and β-glucans. ATR-FTIR thus shows strong potential as a screening tool for selecting starter cultures with desirable autolytic traits in winemaking and broader biotechnological applications.<blockquote><h4>The original article</h4><h4><a target="_blank" rel="noopener noreferrer" href="https://pubs.acs.org/doi/10.1021/acsfoodscitech.5c00022">ATR-FTIR Microspectroscopy as a Tool for Distinguishing Wine-Relevant Saccharomyces spp. Strains Based on Their Autolytic Behavior</a></h4>Renato L. Binati, Nicola Ferremi Leali, Elisa Salvetti, Francesca Monti*, and Sandra TorrianiACS Food Sci. Technol. 2025, 5, 4, 1625–1631<a target="_blank" rel="noopener noreferrer" href="https://doi.org/10.1021/acsfoodscitech.5c00022">https://doi.org/10.1021/acsfoodscitech.5c00022</a><h6>licensed under <a target="_blank" rel="noopener noreferrer" href="https://creativecommons.org/licenses/by/4.0/">CC-BY 4.0</a></h6></blockquote>Selected sections from the article follow. Formats and hyperlinks were adapted from the original.Autolysis is an irreversible phenomenon occurring in yeast cells, associated with cell death at the end of the stationary phase of growth. Several intracellular enzymes are activated to carry out a cascade of reactions to degrade internal and external cell structures with subsequent release of the hydrolysis products into the surrounding medium. Although the autolytic process occurs naturally, in many industrial contexts it can be induced to achieve a faster conclusion of the degradation reactions leading to the production of yeast extracts. In the wine industry, natural autolysis is especially important for the production of wines with prolonged aging on dead yeast lees (e.g., Champagne, Muscadet), notably sparkling wines, but yeast autolysates obtained from induced autolysis are added to different wine styles to achieve flavor enhancements. <a href="javascript:void(0);">(1,2)</a>Appealing yeast cell wall components for winemaking include proteins, peptides, and polysaccharides. The external structure of yeast cells is made of a network of mannoproteins, β-glucans, and chitin. Glucanases and proteases are the main autolytic enzymes involved in cell wall hydrolysis: glucanases hydrolyze the bonded glucans and mannoproteins, which are degraded later onto the protein and polysaccharide fractions by proteolysis. Subsequently, the breakdown of these components and the increased porosity of the cell wall facilitate the release of other cellular compounds, including lipids from plasma membrane degradation, as well as amino acids and ribonucleotides. <a href="javascript:void(0);">(1,3,4)</a>Fourier-transform infrared (FTIR) microspectroscopy offers a reliable method for evaluating the autolysis capacity of new or established yeast starters. <a href="javascript:void(0);">(5)</a> This nondestructive technique allows for the collection of strain-specific absorbance spectra of microbial samples, requiring neither reagents nor extensive sample preparation. Band positions and intensities are interpreted as related to known biochemical functional groups and molecular bonds─such as those of proteins, lipids, carbohydrates, and nucleic acids─providing both qualitative and quantitative insights into the chemical composition of the samples. <a href="javascript:void(0);">(6,7)</a>The analysis of yeast autolytic behavior in a defined growth medium, such as YPD (yeast, dextrose, peptone), using FTIR spectroscopy serves as an excellent screening tool for selecting strains for further in-depth evaluation in wine or wine model systems. <a href="javascript:void(0);">(8)</a> Moreover, it enables precise detection of oenologically significant molecules, such as mannans and glucans, facilitating their potential purification for various applications. <a href="javascript:void(0);">(9)</a>In oenological research, FTIR spectroscopy has been more commonly applied for the inter- and intraspecific discrimination of yeasts from Saccharomyces and non-Saccharomyces species. <a href="javascript:void(0);">(10−13)</a> In one of the first studies, <a href="javascript:void(0);">(14)</a> FTIR spectroscopy has been successfully utilized to discriminate strains belonging to Saccharomyces cerevisiae, the most important wine yeast, and the closely related Saccharomyces bayanus. Other investigations targeted cell modifications and growth-dependent phenomena, including biochemical stress responses to dehydration <a href="javascript:void(0);">(15,16)</a> and biofilm-forming capacity. <a href="javascript:void(0);">(8)</a> Previous studies have demonstrated that FTIR microspectroscopy is an effective tool for investigating the biochemical composition of yeast cells and analyzing structural changes associated with autolysis in S. cerevisiae EC 1118, a widely used industrial strain and a reference standard for sparkling wine production. <a href="javascript:void(0);">(17,18)</a> Recently, <a href="javascript:void(0);">(19)</a> FTIR spectroscopy was employed to compare the structure of yeast’s mannans extracted through different methods, such as thermal hydrolysis and enzymatic hydrolysis, including autolysis.The objective of this study was to apply mid-infrared FTIR microspectroscopy in conjunction with multivariate statistical analysis to investigate the cell wall biochemical composition of Saccharomyces spp. strains during incubation in a defined growth medium. The ultimate goal is to set up a procedure aimed at distinguishing between yeast strains, providing insight into their autolytic behavior; this will allow for the proper selection of the most promising strains to be used in biotechnological applications.<h4>2. Materials and Methods</h4><h5>2.3. FTIR Microspectroscopy</h5>The cell pellets were resuspended in 500 μL of sterile water, and a 10 μL spot of each cellular suspension was deposited, in duplicate, on steel slides, which were previously washed with ultrapure water and ethanol 70% v/v. To dry the droplets, all slides were maintained under ventilation for 24 h, at 40 °C.Mid-infrared absorption spectra were collected in the 1800–700 cm–1 range in the Attenuated Total Reflection (ATR) mode using a Vertex 70 Bruker Optics spectrometer coupled to a Hyperion 3000 vis/IR microscope (Bruker Optics, Germany). The system was equipped with a photoconductive MCT detector and a germanium ATR objective. The ATR mode has an enhanced sensitivity to the biochemical composition of the cell wall due to the reduced penetration depth of the infrared beam inside the sample, determined by the refractive indices of both the objective and the sample, that can be estimated to be around 400 nm at 1800 cm–1 up to 800 nm at 900 cm–1 in the present configuration. This depth, slightly increasing with the wavelength, is greater than the thickness of the cell wall but lower than the total thickness of the cell. <a href="javascript:void(0);">(5)</a> For each sample, i.e., for each time point, about 10 point-by-point spectra were acquired as the ratio of the transmitted to the incident photon intensity by coadding 256 scans at 4 cm–1 (108 s of acquisition time) from a 50 μm × 50 μm area.<h5>2.4. Data Analysis</h5>The software <a target="_blank" rel="noopener noreferrer" href="https://icpms.labrulez.com/library?mainauthorItems=541&amp;search=Opus">Opus 6.0</a> (Bruker Optics) was used for spectra pretreatment, including ATR and baseline correction, average spectra calculation, area normalization, and second derivative calculation to identify the main absorption bands. Principal Component Analysis (PCA) was performed using the statistical packages of the R software version 4.3.1. <a href="javascript:void(0);">(22)</a><h4>3. Results and Discussion</h4>To compare the biochemical characteristics of the studied Saccharomyces spp. strains at the beginning of incubation (day 0) and at the end of the autolytic process (day 5), the corresponding area normalized average absorption spectra are shown in <a target="_blank" rel="noopener noreferrer" href="https://pubs.acs.org/doi/10.1021/acsfoodscitech.5c00022#fig1">Figure 1</a> in the 1800–740 cm–1 range. Since the most meaningful differences among the strains are observed in the 1200–930 cm–1 range, as expected from previous studies on different strains, <a href="javascript:void(0);">(5)</a> the absorption spectra before autolysis and after 5 days of autolysis after baseline correction in this restricted range are also shown, enlarged, in <a target="_blank" rel="noopener noreferrer" href="https://pubs.acs.org/doi/10.1021/acsfoodscitech.5c00022#fig2">Figure 2</a>.<a target="_blank" rel="noopener noreferrer" href="https://pubs.acs.org/doi/10.1021/acsfoodscitech.5c00022#tbl1">Table 1</a> reports the most meaningful absorption bands, as identified through the second derivative on the average absorption spectra (<a target="_blank" rel="noopener noreferrer" href="https://pubs.acs.org/doi/10.1021/acsfoodscitech.5c00022#fig3">Figure 3</a>), and their corresponding assignments.<img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/ACS_Food_Sci_Technol_2025_5_4_1625_1631_Figure_3_Second_derivative_plot_of_the_FTIR_spectra_60ea7e11da.jpg" alt="ACS Food Sci. Technol. 2025, 5, 4, 1625–1631: Figure 3. Second derivative plot of the FTIR spectra in the range 1200–930 cm–1 at 0 (left) and 120 h (right) for S. cerevisiae EC 1118 (black), CH (red), FR-B (blue), and S. bayanus Q20 (green)." srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_ACS_Food_Sci_Technol_2025_5_4_1625_1631_Figure_3_Second_derivative_plot_of_the_FTIR_spectra_60ea7e11da.jpg 245w," sizes="100vw" width="1500" height="698">In ATR spectra, due to the limited infrared beam penetration depth inside the sample, the detected composition on each strain reflects the interplay between the relative concentrations of the various biochemical components within the entire cell and the relative thickness of the cell wall. Notably, in the 1200–930 cm–1 range, most relevant biochemical components <a href="javascript:void(0);">(5)</a> are primarily associated with the cell wall, except for the phosphate band at 1080 cm–1, which is mainly related to intracellular nucleic acids and membrane phospholipids.The behavior of second derivative spectra (<a target="_blank" rel="noopener noreferrer" href="https://pubs.acs.org/doi/10.1021/acsfoodscitech.5c00022#fig3">Figure 3</a>) at day 0 and after autolysis at day 5 highlights that the absorption bands that better discriminate the four spectra are those at 1050 cm–1 (mannans), 1030 cm–1 (β-1-4 glucans) and 995 cm–1 (β-1-6 glucans).At day 0, the contribution of the band at 1050 cm–1 is either higher than or approximately equal to the band at 1030 cm–1 in CH and FR-B, respectively, whereas the opposite behavior is observed in EC 1118 and Q20, where the contribution of the 1030 cm–1 band is higher than that at 1050 cm–1. Conversely, the band at 995 cm–1 is more intense in EC 1118 and FR-B, while it is lower in CH and Q20. The band at 1080 cm–1 exhibits a similar intensity across all strains.After 5 days, the behavior of the 1080 cm–1 band differs among the four strains. The 1050 cm–1 band has the same intensity in all of the strains, while the 1030 cm–1 band increases and tends to be more intense than the 1050 cm–1 band, with the lowest intensity again observed in CH as compared to the other strains. The 995 cm–1 band increases in intensity in all of the strains relative to day 0, but it remains notably lower in CH as compared to the other strains.To better highlight the effect of autolysis on each strain, absorption spectra at day 0 and at day 5 are compared strain by strain in <a target="_blank" rel="noopener noreferrer" href="https://pubs.acs.org/doi/10.1021/acsfoodscitech.5c00022#fig4">Figure 4</a>.<img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/ACS_Food_Sci_Technol_2025_5_4_1625_1631_Figure_4_Area_normalized_average_absorption_spectra_after_baseline_correction_103d6ebeb3.jpg" alt="ACS Food Sci. Technol. 2025, 5, 4, 1625–1631: Figure 4. Area normalized average absorption spectra after baseline correction in the restricted range 1200–930 cm–1 at day 0 (red) and day 5 (black) for S. cerevisiae CH (a), S. bayanus Q20 (b), S. cerevisiae EC 1118 (c), and S. cerevisiae FR-B (d)." srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_ACS_Food_Sci_Technol_2025_5_4_1625_1631_Figure_4_Area_normalized_average_absorption_spectra_after_baseline_correction_103d6ebeb3.jpg 245w," sizes="100vw" width="1429" height="693">These results confirmed that the autolytic behavior and associated biochemical processes are strain-dependent, leading to the formation of two distinct strain clusters. In terms of temporal trends, CH and Q20 exhibited slower transitions, whereas EC 1118 showed the fastest evolution, followed by FR-B. Regarding biochemical modifications associated with cell lysis, EC 1118 displayed greater similarity to Q20, particularly in the degradation of β-1,6 glucans. Overall, this FTIR-based method proved to be an effective tool for distinguishing between yeast strains, enabling the screening of starters for wine styles in which yeast autolysis is a key factor in determining wine quality.In the future, this valuable method could also be applied to evaluate the autolytic behavior of non-Saccharomyces yeast strains that are increasingly used in winemaking to differentiate the sensory profile of wine.

ATR-FTIR Microspectroscopy as a Tool for Distinguishing Wine-Relevant Saccharomyces spp. Strains Based on Their Autolytic Behavior

This study investigates the relationship between fruit development and seed quality in the “Hua Rue” hot chili cultivar. Seeds harvested at 35, 45, and 50 days after flowering were evaluated for physical traits, germination performance, tissue-specific chemical composition using FTIR microspectroscopy, and biochemical activity during imbibition.Seeds collected at 50 days after flowering showed the highest weight, germination rate, and germination speed, accompanied by increased endosperm-associated chemical accumulation and enhanced metabolic activity. FTIR analysis clearly distinguished developmental stages based on tissue-specific chemical signatures, identifying 50 DAF as the optimal harvest stage for producing high-quality chili seeds with stable storage viability.<blockquote><h4>The original article</h4><h4><a target="_blank" rel="noopener noreferrer" href="https://pubs.acs.org/doi/10.1021/acsomega.5c05947">Chemical Composition and Biochemical Changes during Fruit Development on Seed Quality in Hot Chili (Capsicum annuum L.)</a></h4>Wissanee Pola*, Songsin Photchanachai, and Papungkorn SangsawadACS Omega 2026, 11, 1, 562–571<a target="_blank" rel="noopener noreferrer" href="https://doi.org/10.1021/acsomega.5c05947">https://doi.org/10.1021/acsomega.5c05947</a><h6>licensed under <a target="_blank" rel="noopener noreferrer" href="https://creativecommons.org/licenses/by/4.0/">CC-BY 4.0</a></h6></blockquote>Selected sections from the article follow. Formats and hyperlinks were adapted from the original.<div>Hot chili (Capsicum annuum L.), specifically the “Hua Rue” cultivar, is popular in the northeast region of Thailand due to its distinctive pungency and high yield. <a href="javascript:void(0);">(1)</a> Thailand ranks among the top five chili producers in Asia and is a leading exporter worldwide, with an export volume of approximately 60,000 kg and a value of 805 million baht. It is evident that chili seeds play a significant role in the country’s agricultural economy. <a href="javascript:void(0);">(2)</a> Seed production is a critical process that ensures the availability of high-quality seeds for sustainable crop production. Generally, in the large-scale production of this chili cultivar, mature fruits are harvested manually at the fully red-ripe stage, and the seeds are extracted from sun-dried fruits. However, the seed quality tends to decline rapidly during storage, particularly after six months. <a href="javascript:void(0);">(2)</a>Typically, harvesting chili fruits at the onset of ripening is necessary for producing high-quality seeds. <a href="javascript:void(0);">(3)</a> Seeds achieve physiological maturity (PM) when they attain maximum dry weight and vigor, which vary with the variety. <a href="javascript:void(0);">(4)</a> In Capsicum species, high seed quality was achieved in fruits harvested at 50–60 days after flowering (DAF). <a href="javascript:void(0);">(5)</a> Research on sweet pepper and hot chili varieties suggested that seeds extracted at 60 DAF provided the highest germination and vigor. <a href="javascript:void(0);">(6)</a> Furthermore, enzymatic hydrolysis of storage macromolecules, particularly starch breakdown by α-amylase, is crucial for seed germination. <a href="javascript:void(0);">(7)</a> This enzyme hydrolyzes starch in the cotyledon and endosperm into simple sugar units that are then synthesized into sucrose for transport to the embryonic axis. <a href="javascript:void(0);">(8)</a>Fourier transform infrared microspectroscopy (FTIR) is a technique used to obtain an infrared spectrum of absorption or emission of solids, liquids, and gases. <a href="javascript:void(0);">(9)</a> An FTIR spectrometer collects high-resolution spectral data over a wide spectral range simultaneously, providing a significant advantage over a dispersive spectrometer, which measures the intensity over a narrow range of wavelengths at a time. This instrument is effective for identifying biochemical compositions in living cells and tissues. <a href="javascript:void(0);">(10)</a> FTIR spectra typically reveal absorption bands corresponding to lipids (3000–2800 cm–1), proteins (1700–1480 cm–1), carbohydrates, and nucleic acids (1450–600 cm–1). <a href="javascript:void(0);">(11)</a> The measurement of chemical compositions in chili seeds using FTIR, particularly concerning the physiological maturity (PM) stage of the “Hua Rue” variety, has not been documented in recent years. The measurement of chemical compositions in chili seeds using FTIR, particularly in relation to the physiological maturity (PM) stage of the “Hua Rue” variety, has not been reported in recent years. Previous studies have mainly evaluated seed quality based on whole-seed analyses and standard germination tests. In contrast, this study provides the first detailed characterization of chemical composition profiles of individual seed organs in the “Hua Rue” variety. For this purpose, fruits were harvested at different developmental stages to investigate biochemical changes during ripening. Although the general postharvest handling and storage methods used in this study (manual extraction, shade drying, and sealed storage) slightly differ from the traditional practices employed by local seed producers, they were designed to ensure consistent sample quality for analysis. Therefore, this study aims to investigate the biochemical and chemical composition profiles of seed organs (embryonic axis, endosperm, and seed coat) as extracted from “Hua Rue” chili at various fruit developmental stages and to explore their potential relationship with seed vigor and storability.<h4>2. Materials and Methods</h4><h5>2.3. Fourier-Transform Infrared (FTIR) Microspectroscopy of Seed Tissues</h5>Seeds were collected from chili pods at three fruit developmental stages: 35, 45, and 50 DAF. Immediately after extraction, ten seeds per stage were embedded in optimal cutting temperature (OCT) compound (Tissue-Tek O.C.T. Compound, USA) and snap-frozen to preserve biochemical integrity. The embedded seeds were sectioned at −20 °C into cross sections of 8 ± 1 μm using a Leica CM1950 microtome cryostat (Cambridge Scientific). Sections were mounted on calcium fluoride (CaF2) infrared-transparent windows to facilitate FTIR analysis. Chemical imaging was performed using a <a target="_blank" rel="noopener noreferrer" href="https://icpms.labrulez.com/library?manufacturerItems=10&amp;search=HYPERION">HYPERION 3000 FTIR microscope </a>(Bruker Optik GmbH) equipped with a focal plane array (FPA) detector, operating in the spectral range of 4000–600 cm–1, with 64 scans per spectrum. Spectral acquisition and preliminary processing were carried out by using <a target="_blank" rel="noopener noreferrer" href="https://icpms.labrulez.com/library?manufacturerItems=10&amp;search=OPUS+software">OPUS 7.5 software</a> (Bruker Optics, Ettlingen, Germany). The spectra were subsequently exported to Unscrambler X 10.5 for multivariate analysis, including the Savitzky–Golay second-derivative transformation, extended multiplicative signal correction (EMSC) normalization, and principal component analysis (PCA). The FTIR microspectroscopy was used to observe spectral pattern differences among tissues and maturation stages. Anatomical regions analyzed included the seed coat, endosperm, and embryonic axis.<h4>3. Results and Discussion</h4><h5>3.1. Effect of Fruit Development on Seed Anatomy and 1000-Seed Weight</h5>Visual observations of the ″Hua Rue” chili fruits showed mature green, breaker, and mature red colors at 35, 45, and 50 DAF, respectively (<a target="_blank" rel="noopener noreferrer" href="https://pubs.acs.org/doi/10.1021/acsomega.5c05947#fig1">Figure 1</a>A). This closely aligns with the ripening stages of the red pepper “Zunla-1” cultivar, as reported by Song et al. <a href="javascript:void(0);">(17)</a> where the ripening stages were divided into mature green (30 DAF), breaker (35 DAF), first immature red (38 DAF), second immature red (43 DAF), and mature red (MR, approximately 50 DAF).<img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/ACS_Omega_2026_11_1_562_571_Figure_1_Appearance_of_Hua_Rue_chili_fruits_and_the_interior_seed_structure_including_seed_coat_endosperm_and_embryonic_axis_cd5e87f491.jpeg" alt="ACS Omega 2026, 11, 1, 562–571: Figure 1. Appearance of “Hua Rue” chili fruits and the interior seed structure, including seed coat, endosperm, and embryonic axis (A), and the 1000-seed weight (B) as extracted from the harvested fruits at 35, 45, and 50 days after flowering (DAF). Values are means ± SD (n = 4). Different letters (a, b) denote significant differences among treatments according to Tukey’s HSD Test (P &lt; 0.05)." srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_ACS_Omega_2026_11_1_562_571_Figure_1_Appearance_of_Hua_Rue_chili_fruits_and_the_interior_seed_structure_including_seed_coat_endosperm_and_embryonic_axis_cd5e87f491.jpeg 245w," sizes="100vw" width="1000" height="518">After the seeds were extracted from each fruit development stage, the interior structure of the seeds, including the endosperm and embryonic axis (cotyledons and radicle), was found to be fully developed at 45 and 50 DAF. In contrast, seeds from 35 DAF exhibited shorter cotyledons, indicating incomplete development (<a target="_blank" rel="noopener noreferrer" href="https://pubs.acs.org/doi/10.1021/acsomega.5c05947#fig1">Figure 1</a>A). This interior structure of chili seeds can determine seed physical integrity and predict seedling emergence. A previous study on bell pepper found that the structural integrity of seeds, as assessed by X-ray analysis, was linked to germination performance. It was discovered that a decrease in the internal area occupied by the embryo and endosperm was directly related to the incidence of abnormal seedlings and nongerminated seeds. <a href="javascript:void(0);">(18)</a> Nevertheless, the most crucial structure of the seed is the embryonic axis, which develops into the seedling. Therefore, a fully developed embryonic axis is essential for seed production.Generally, harvesting seeds at the physiological maturity (PM) stage, which indicates the highest seed vigor and viability, is essential for cultivation. The major indicators of the PM stage are maximum seed dry weight, high seed vigor, and germination percentage. <a href="javascript:void(0);">(6)</a> In this study, the 1000-seed weight of “Hua Rue” chili ranged from 3563 to 4983 mg (<a target="_blank" rel="noopener noreferrer" href="https://pubs.acs.org/doi/10.1021/acsomega.5c05947#fig1">Figure 1</a>B). A significant difference in seed weight was observed between the fruit developmental stages. The lowest value was found in seeds extracted from fruit harvested at 35 DAF. Meanwhile, seeds obtained from fruit harvested at 45 and 50 DAF showed a gradual increase in weight. This indicates that early harvested chili fruit, whose seeds have reached the PM stage, should be at 45–50 DAF. Similarly, Yisa et al. <a href="javascript:void(0);">(19)</a> studied the influence of fruits at different stages (12–48 DAF) on seed quality. Their results revealed a continual increase in dry seed weight throughout the maturation process, particularly in seeds extracted from fruits harvested at 48 DAF. Similarly, Pagamas and Nawata <a href="javascript:void(0);">(20)</a> reported increasing dry seed weight in chili pepper cultivars “Huay Si Thon” and “Shishito” from 35 to 45 DAF that remained until 60 DAF. Hence, they recommended that the optimal harvest maturity period for “Huay Si Thon” and “Shishito” was at 45 DAF and 55 DAF, respectively. This suggests that harvesting during this period could yield good seed quality based on seed weight parameters, which may indicate the accumulation of nutrients in the seeds.<h5>3.2. Effect of Fruit Development on Chemical Composition Profiles of Seeds Analyzed by FTIR Microspectroscopy</h5>Hyperspectral images of the interior organs (embryonic axis, endosperm, and seed coat) extracted from different stages of fruit development in “Hua Rue” chili are shown in <a target="_blank" rel="noopener noreferrer" href="https://pubs.acs.org/doi/10.1021/acsomega.5c05947#fig2">Figure 2</a>. The color-coded regions represent variations in intensity, possibly indicating differences in chemical composition, thermal properties, or structural variations in various seed tissues. The 35 DAF seed exhibited a higher abundance of chemicals in the endosperm region, as indicated by the red color in the tissue, while it showed a lower composition in the seed coat and embryonic axis (<a target="_blank" rel="noopener noreferrer" href="https://pubs.acs.org/doi/10.1021/acsomega.5c05947#fig2">Figure 2</a>A). The seeds from 45 and 50 DAF contained the highest concentrations of chemicals in the endosperm, followed by the embryonic axis and seed coat (<a target="_blank" rel="noopener noreferrer" href="https://pubs.acs.org/doi/10.1021/acsomega.5c05947#fig2">Figure 2</a>B,C). These results indicate that the chemical compositions in each region of the seed vary, depending on the stages of seed development. In a previous study, a Raman hyperspectral imaging system was applied for online quality control of maize seeds based on the rapid and visual detection of chemical compositions. <a href="javascript:void(0);">(21)</a><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/ACS_Omega_2026_11_1_562_571_Figure_2_Hyperspectral_imaging_of_chili_seed_tissues_at_different_fruit_developmental_stages_f9a7b4a922.jpeg" alt="ACS Omega 2026, 11, 1, 562–571: Figure 2. Hyperspectral imaging of chili seed tissues at different fruit developmental stages: 35 days after flowering (DAF, A), 45 DAF (B), and 50 DAF (C). Seed coat, endosperm, and embryonic axis regions are indicated. The overlaid false-color maps represent the relative chemical abundance detected by hyperspectral analysis, with a color scale from −200 (blue, lowest intensity) to 1000 (white-pink, highest intensity)." srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_ACS_Omega_2026_11_1_562_571_Figure_2_Hyperspectral_imaging_of_chili_seed_tissues_at_different_fruit_developmental_stages_f9a7b4a922.jpeg 245w," sizes="100vw" width="2088" height="593">The FTIR spectrum was recently applied to identify the intensity of biochemical compositions in various materials. <a href="javascript:void(0);">(22)</a> In the FTIR absorption spectrum, three major biochemical composition regions of interest have been identified according to prior studies. <a href="javascript:void(0);">(23)</a> The absorption bands of 3000–2800 cm–1 represent lipid regions, the bands of 1800–1400 cm–1 exhibit protein regions (amide I and amide II), and the spectra absorption bands of 1300–1000 cm–1 reveal carbohydrates, phospholipids, and nucleic acids. <a href="javascript:void(0);">(24,10)</a> In this study, distinctive spectral patterns were observed among the embryonic axis, endosperm, and seed coat (<a target="_blank" rel="noopener noreferrer" href="https://pubs.acs.org/doi/10.1021/acsomega.5c05947#fig3">Figure 3</a>A–C). Additionally, significant differences in absorption intensities were found among seeds extracted from fruit at 35, 45, and 50 DAF (<a target="_blank" rel="noopener noreferrer" href="https://pubs.acs.org/doi/10.1021/acsomega.5c05947#fig3">Figure 3</a>D–F).<img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/ACS_Omega_2026_11_1_562_571_Figure_3_FTIR_analysis_of_chili_seed_tissues_harvested_at_different_developmental_stages_62c5db783d.jpeg" alt="ACS Omega 2026, 11, 1, 562–571: Figure 3. FTIR analysis of chili seed tissues harvested at different developmental stages. (A–C) Mean absorption spectra of the seed coat (A), endosperm (B), and embryonic axis (C) obtained from seeds at 35, 45, and 50 days after flowering (DAF). Major absorption peaks are indicated: 2927–2850 cm–1 (C–H stretching of lipids), 1745–1660 cm–1 (amide I of proteins), 1543–1380 cm–1 (amide II of proteins), and 1234–1090 cm–1 (C–O stretching of carbohydrates/polysaccharides). (D–F) Quantitative comparisons of relative absorbance intensities at these peaks for the seed coat (D), endosperm (E), and embryonic axis (F). Bars represent the mean ± standard deviation (SD). Different letters (a–c) above bars indicate statistically significant differences among fruit developmental stages according to Tukey’s HSD test (P &lt; 0.05)." srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_ACS_Omega_2026_11_1_562_571_Figure_3_FTIR_analysis_of_chili_seed_tissues_harvested_at_different_developmental_stages_62c5db783d.jpeg 237w," sizes="100vw" width="2088" height="1372"></div>

Chemical Composition and Biochemical Changes during Fruit Development on Seed Quality in Hot Chili (Capsicum annuum L.)

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