Dynamic changes of phenolic acids and antioxidant activity of Citri Reticulatae Pericarpium during aging processes

Determination of eleven components in rat plasma by UPLC-MS/MS and GC-MS for pharmacokinetic studies after oral administration of Citri Reticulatae Pericarpium extract

Citri Reticulatae Pericarpium (CRP) is used as common health-care food and traditional Chinese medicine (TCM), which exerts pharmacological effects, such as anti-cardiovascular, anti-tumor, anti-oxidant, anti-inflammatory, anti-virus, hepatoprotective, blood pressure-lowering and neuroprotective. In this study, reliable, and sensitive ultra-high performance liquid chromatography/tandem mass spectrometry (UPLC-MS/MS) and gas chromatography-mass spectrometry (GC-MS) methods were developed and validated for the determination of eleven active components in rat plasma after oral administration of the CRP extract. The results of this method exhibited that the specificity, linearity (r > 0.999), precision and accuracy (the coefficient of variation (CV) < 11.5 %), recovery (52.9-107.9 %), matrix effects (63.8-107.5 %), and stability (CV < 10.8 %) met all requirements for the quantitation of plasma samples. The pharmacokinetic results showed that the Tmax of flavone glycosides was less than 0.7 h, and that of polymethoxyflavones and volatile components were within 1-7 h. Meanwhile, the area-under-the-curve (AUC) and concentration maximum (Cmax) of hesperidin, nobiletin, tangeretin, and D-limonene were higher than those of the other components, suggesting that the plasma exposure levels of these constituents were higher in CRP. The present research lays a foundation for elucidating the therapeutic material basis and provides a reference for further scientific research and clinical application of CRP.

Evaluation of chemical components and quality in Xinhui Chenpi (Citrus reticulata 'Chachi') with two different storage times by GC-MS and UPLC

Xinhui Chenpi (XHCP) is a well-known type of Chenpi (CP) widely used as both a Chinese herb and a food ingredient. While previous studies have explored how the quality of CP changes over time, there has been limited research specifically on XHCP. This study aims to assess the chemical components and quality of XHCP based on total flavonoid content (TF), antioxidant activity (AA), and color value (CV) at two stages: freshly harvested (XHCP-0Y) and after 3 years of storage (XHCP-3Y). Thirty-eight common volatile compounds were identified, and the content of 17 compounds among them, nine nonvolatile compounds, which included one alkaloid (synephrine), three phenolic acids (PA, protocatechuic acid, vanillic acid, and ferulic acid), and five flavonoids (narirutin, hesperidin, sinensetin, nobiletin, and tangeretin), were firstly detected by the newly developed gas chromatograph-mass spectrometer (GC-MS) and ultra-performance liquid chromatography (UPLC) methods. Compared to XHCP-0Y, the content of 17 volatile compounds and synephrine decreased in XHCP-3Y to varying degrees, while the content of PA, five flavonoids, TF, AA, and CV increased. The reduction of dryness caused by volatile compounds and the enhancement of efficacy related to PA, flavonoids, and AA suggested improved quality of XHCP after 3 years of storage. The methods developed in this study show promise for evaluating the quality of XHCP during the aging process.

Uncovering the antiinflammatory potential of Lactiplantibacillus Plantarum fermented Cannabis Sativa L seeds

Inflammation acts as a dual role in disease initiation and progression, while Cannabis sativa L. (hemp) seeds, known for their abundance of anti-inflammatory phytochemicals, present a promising food source. Additionally, fermentation may optimize the food matrix, thereby augmenting its developmental prospects. This study explores the anti-inflammatory potential of hemp seeds fermented with 10 different probiotic strains. Among these, Lactiplantibacillus plantarum fermented hemp seeds (FHS) demonstrated a significant anti-inflammatory ability, accompanied by a reduction in the expression of critical inflammatory markers such as TLR4, NF-κBp65, and iNOS. Moreover, there is a noteworthy dose-dependent inhibition of inflammatory cytokines TNF-α, IL-6, IL-1β, and NO within a concentration range of 50 to 500 µg/mL. Subsequently, metabolomics analysis using UHPLC-QTOF-MS highlighted significant metabolic alterations in FHS compared to raw hemp seeds (RHS). Through multivariate, univariate, and correlation analyses, indolelactic acid (IA) and homovanillic acid (HVA) emerged as the main anti-inflammatory metabolites in FHS. Validation via HPLC confirmed the concentration of IA and HVA in RHS and FHS and both organic acids demonstrated lower IC50 values for TNF-α, IL-1β, IL-6, IL-18, and NO inhibition, showcasing their potent anti-inflammatory abilities. Furthermore, in vitro gastro-intestinal digestion coupled with the Caco-2 cell monolayer model validates the uptake and bioaccessibility of FHS, further affirming IA and HVA as major anti-inflammatory compounds. Overall, this research sets the stage for the development of novel hemp seed-based products targeting inflammation-associated disorders.

Application of flash GC e-nose and FT-NIR combined with deep learning algorithm in preventing age fraud and quality evaluation of pericarpium citri reticulatae

Pericarpium citri reticulatae (PCR) is the dried mature fruit peel of Citrus reticulata Blanco and its cultivated varieties in the Brassicaceae family. It can be used as both food and medicine, and has the effect of relieving cough and phlegm, and promoting digestion. The smell and medicinal properties of PCR are aged over the years; only varieties with aging value can be called "Chenpi". That is to say, the storage year of PCR has a great influence on its quality. As the color and smell of PCR of different storage years are similar, some unscrupulous merchants often use PCRs of low years to pretend to be PCRs of high years, and make huge profits. Therefore, we did this study with the aim of establishing a rapid and nondestructive method to identify the counterfeiting of PCR storage year, so as to protect the legitimate rights and interests of consumers. In this study, a classification model of PCR was established by e-eye, flash GC e-nose, and Fourier transform near-infrared (FT-NIR) combined with machine learning algorithms, which can quickly and accurately distinguish PCRs of different storage years. DFA and PLS-DA models were established by flash GC e-nose to distinguish PCRs of different ages, and 8 odor components were identified, among which (+)-limonene and γ-terpinene were the key components to distinguish PCRs of different ages. In addition, the classification and calibration model of PCRs were established by the combination of FT-NIR and machine learning algorithms. The classification models included SVM, KNN, LSTM, and CNN-LSTM, while the calibration models included PLSR, LSTM, and CNN-LSTM. Among them, the CNN-LSTM model built by internal capsule had significantly better classification and calibration performance than the other models. The accuracy of the classification model was 98.21 %. The R2P of age, (+)-limonene and γ-terpinene was 0.9912, 0.9875 and 0.9891, respectively. These results showed that the combination of flash GC e-nose and FT-NIR combined with deep learning algorithm could quickly and accurately distinguish PCRs of different ages. It also provided an effective and reliable method to monitor the quality of PCR in the market.

Diversity in storage age enables discrepancy in quality attributes and metabolic profile of Citrus grandis "Tomentosa" in China

The folk proverb "the older, the better" is usually used to describe the quality of Citrus grandis "Tomentosa" (CGT) in China. In this study, CGT aged for 6-, 12-, 16-, and 19-years were collected for the investigation of infusion color, main bioactive components, antioxidant activity, metabolic composition, and pathway. The results found that infusion color, the total phenolic and flavonoid, and antioxidant activity of CGT were obviously changed by aging process. Through untargeted metabolomics, 55 critical metabolites were identified to in discrimination of CGT with different storage ages, mainly including phenylpropanoids, lipids, and organic oxygen compounds. Twenty compounds that showed good linear relationships with storage ages could be used for year prediction of CGT. Kyoto encyclopedia of genes and genomes enrichment pathway analysis uncovered important metabolic pathways related to the accumulation of naringin, kaempferol, and choline as well as the degradation of benzenoids, thus supporting that aged CGT might be more beneficial to health. Correlation analysis provided that some key metabolites with bitter taste and biological activity were involved in the darkening and reddening of CGT infusion during aging, and total phenolic and flavonoid were more strongly associated with the antioxidant activity of CGT. This study systematically revealed the quality changes and key metabolic pathways during CGT aging at first time. PRACTICAL APPLICATION: This study reveals the differences in quality attributes and metabolic profile between CGT with different storage ages, providing guidance for consumers' consumption, and also providing more scientific basis for the quality evaluation and improvement of CGT.

Metabolism and release of characteristic components and their enzymatic mechanisms in Pericarpium Citri Reticulatae co-fermentation

A co-fermentation strategy was explored to rapidly improve the characteristic components and quality of Pericarpium Citri Reticulatae (PCR) using Monascus anka and Saccharomyces cerevisiae, and the enzymatic mechanism was investigated. The results showed that the free flavonoid content of fermented PCR was 48.12% higher than that of unfermented PCR after 12 days of co-fermentation, resulting in stronger antioxidant activity. d-Limonene, γ-terpinene, proline (Pro), arginine (Arg), and serine (Ser) contributed the most to the flavors of citrus, herb, and sweet citrus based on odor and taste activity value analysis. Metabolomics and multivariate statistics showed that 55 components were differentially metabolized during co-fermentation, and ten metabolic pathways were closely related to metabolism. Furthermore, five hydrolases participated in the release and conversion of the active ingredients. This study provides an effective processing method for PCR and is conducive to the development of new PCR functional health foods.

Another thread to uncover the aging mystery of white tea: Focusing on the natural nanoparticles in tea infusion

Aged white tea (WT) has promising medicinal potential, but how to accurately identify aged white tea is still a difficult problem. Inspired by tea cream, the relationship between the characteristics of nanoparticles in tea infusion and aging time was studied. The results showed that with the increase of aging time, the particle size of white tea nanoparticles (WTNs) decreased gradually. Microscopic images showed that the surface structure of WTNs was changed in three aspects: the waxy layer, the cuticle layer and the palisade tissue. Additional in vitro modeling demonstrated a strong correlation between nanoparticle size and protein and tea polyphenol content. The correlation between nanoparticle sizes and aging time was further verified in aged Pu'er raw tea. Starting with the tea infusion's nanoparticles, this study showed that the aging time of WT would impact the nanoparticles' properties, offering a unique way to determine the aging period of WT.

Integrated metabolomics and network pharmacology to reveal antioxidant mechanisms and potential pharmacological ingredients of citrus herbs

The benefits of citrus herbs are strongly associated with their secondary metabolites. In the study, we conducted widely-targeted metabolomics and ultra-high performance liquid chromatography (UPLC) to compare the variability of ingredients in four citrus herbs. In total, we discovered 1126 secondary metabolites, primarily comprising flavonoids, phenolic acids, lignans and coumarins, and alkaloids. Differential metabolites of citrus herbs were searched by multivariate statistical analysis. Notably, Citri Reticulatae Pericarpium contained higher levels of flavonoids, while Zhique and Huajuhong demonstrated a greater abundance of coumarins. Among the flavonoids determined by UPLC, Guangchenpi demonstrated significantly elevated levels of polymethoxyflavones (tangeretin and nobiletin) compared to other citrus herbs. Additionally, we determined their antioxidant capacity (Chenpi > Guangchenpi > Huajuhong > Zhique) using in vitro assays. Finally, we utilized network pharmacology to explore the antioxidant mechanisms and potential pharmacological ingredients, providing a basis for future preventive and therapeutic applications of these metabolites.

Exploring the roles of microorganisms and metabolites in the 30-year aging process of the dried pericarps of Citrus reticulata 'Chachi' based on high-throughput sequencing and comparative metabolomics

GuangChenpi (GCP), the dried pericarps of Citrus reticulata 'Chachi', has been consumed daily as a food and dietary supplement in China for centuries. Its health benefits are generally recognized to be dependent on storage time. However, the specific roles of microorganisms and metabolites during long-term storage are still unclear. In this study, comparative metabolomics and high-throughput sequencing techniques were used to investigate the effects of co-existing microorganisms on the metabolites in GCP stored from 1 to 30 years. In total, 386 metabolites were identified and characterized. Most compounds were flavonoids (37%), followed by phenolic acids (20%). Seventeen differentially upregulated metabolites were identified as potential key metabolites in GCP, and 8 of them were screened out as key active ingredients by Venn diagram comparative analyses and verified by network pharmacology and molecular docking. In addition, long-term storage could promote the accumulation of secondary metabolites. Regarding the GCP microbiota, Xeromyces dominated the whole 30-year aging process.Moreover, Spearman correlation analysis indicated that Bacillus thuringiensis and Xeromyces bisporus, the dominant bacterial and fungal species, were strongly associated with the key active metabolites. Our results suggested that the change of active ingredients caused by the dominant microbial is one of the mechanisms affecting the GCP aging process. Our study provides novel functional insights and research perspectives on microorganism-associated metabolite changes that may improve the GCP aging process.

Research advances in citrus polyphenols: green extraction technologies, gut homeostasis regulation, and nano-targeted delivery system application

Citrus polyphenols can modulate gut microbiota and such bi-directional interaction that can yield metabolites such as short-chain fatty acids (SCFAs) to aid in gut homeostasis. Such interaction provides citrus polyphenols with powerful prebiotic potential, contributing to guts' health status and metabolic regulation. Citrus polyphenols encompass unique polymethoxy flavonoids imparting non-polar nature that improve their bioactivities and ability to penetrate the blood-brain barrier. Green extraction technology targeting recovery of these polyphenols has received increasing attention due to its advantages of high extraction yield, short extraction time, low solvent consumption, and environmental friendliness. However, the low bioavailability of citrus polyphenols limits their applications in extraction from citrus by-products. Meanwhile, nano-encapsulation technology may serve as a promising approach to improve citrus polyphenols' bioavailability. As citrus polyphenols encompass multiple hydroxyl groups, they are potential to interact with bio-macromolecules such as proteins and polysaccharides in nano-encapsulated systems that can improve their bioavailability. This multifaceted review provides a research basis for the green and efficient extraction techniques of citrus polyphenols, as well as integrated mechanisms for its anti-inflammation, alleviating metabolic syndrome, and regulating gut homeostasis, which is more capitalized upon using nano-delivery systems as discussed in that review to maximize their health and food applications.

Review of recent advances on health benefits, microbial transformations, and authenticity identification of Citri reticulatae Pericarpium bioactive compounds

The extensive health-promoting effects of Citri Reticulatae Pericarpium (CRP) have attracted researchers' interest. The difference in storage time, varieties and origin of CRP are closely related to the content of bioactive compounds they contain. The consitituent transformation mediated by environmental microorganisms (bacteria and fungi) and the production of new bioactive components during the storage process may be the main reason for 'the older, the better' of CRP. In addition, the gap in price between different varieties can be as large as 8 times, while the difference due to age can even reach 20 times, making the 'marketing young-CRP as old-CRP and counterfeiting origin' flood the entire market, seriously harming consumers' interests. However, so far, the research on CRP is relatively decentralized. In particular, a summary of the microbial transformation and authenticity identification of CRP has not been reported. Therefore, this review systematically summarized the recent advances on the main bioactive compounds, the major biological activities, the microbial transformation process, the structure, and content changes of the active substances during the transformation process, and authenticity identification of CRP. Furthermore, challenges and perspectives concerning the future research on CRP were proposed.

Effects of ageing time on the properties of polysaccharide in tangerine peel and its bacterial community

To evaluate the effect of aging time on the quality of tangerine peel (TP) from the perspective of TP polysaccharide (TPP), five polysaccharide samples with different aging times named TPP-0/1/5/10/15 were prepared. Under the conditions of pH 0.5, solid-liquid ratio 1:25 and 80 °C, the TPPs extraction yield ranged from 20.35% to 27.68%. Compared with TPP-0, TPP-1/5/10/15 possesses low molecular weight (Mw) and high methoxy group content. In addition, TPP-15 had the most potent antioxidant activity. And the content of acidic polysaccharides in TPPs was negatively correlated with neutral polysaccharides during aging. Based on the analysis of 16srDNA, the dominant bacteria (Brevundimonas and Pseudomonas) in TP-10 might be critical flora to affect TP quality. This study provided basic information on the relationship between the TPPs and aging time, which could promote a new view to develop TP, and shorten the aging time during TP production.

Quality control strategies of medicine food homology materials based on fingerprint profiling and chemometrics: Citri Reticulata Pericarpium as an example

The study aimed to provide a reliable and feasible strategy for the comprehensive quality control of medicine food homology materials (MFHM). The high performance liquid chromatography (HPLC) fingerprints and Fourier transform mid-infrared (FT-MIR) quantized fingerprints were successfully developed to comprehensively evaluate overall quality of Citri Reticulata Pericarpium (CRP) by applying comprehensive quantified fingerprint method (CQFM). All samples were well distinguished and divided into 5 grades. In addition, through principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA), the identification ability of HPLC fingerprints and FT-MIR fingerprints on CRP with different storage years was discussed. The results showed that HPLC fingerprints combined with PCA had good discrimination ability, and the PLS-DA model established by the preprocessed FT-MIR fingerprint data could accurately distinguish and predict the storage period of CRP. Finally, based on 1, 1-diphenyl-2-picrylhydrazyl radical (DPPH•) scavenging assay, combined with bivariate correlation analysis, the fingerprint-activity relationship of offline antioxidant activity of CRP samples with the fingerprints peak were studied. In general, the comprehensive strategies provide a reliable and scientific reference scheme for the quality control of MFHM in the future.

Extraction optimization, purification, and biological properties of polysaccharide from Chinese yam peel

In this study, the Chinese yam peel polysaccharide (CYPP) was obtained under the extraction conditions optimized by the Response Surface Methodology (RSM). Further biological properties of CYPP-1 purified from CYPP were also determined. The results indicated that the optimum extraction conditions were an extraction temperature of 90.5°C, a liquid-solid ratio of 28.0 ml/g, and an extraction time of 2.94 h, along with a yield of 8.81 ± 1.48%. CYPP-1 was identified as a kind of heteropolysaccharide mostly composed of glucose and galactose (59.4:1.0). The molecular weights were two main parts of 50.5 kDa (54.77%) and 4.4 kDa (21.02%), and the triple-helix conformation was not formed in CYPP-1. Besides, CYPP-1 showed good biological properties including in vitro antioxidant activity and immunomodulatory function on RAW264.7 cells, as well as favorable hypoglycemic effect. Overall, the high-value utilization of CYPP-1 reveals a broad application prospect in the industrial production of functional foods and pharmaceuticals. PRACTICAL APPLICATIONS: Yam peel, which is discarded in large quantities during postharvest processing, results in the production of tremendous by-products and is a great waste of resources. In this study, the yield of water-soluble polysaccharide from yam peel reached 8.81 ± 1.48%. Besides, the purified CYPP-1 exhibited excellent antioxidant activity, favorable immunomodulatory function, and hypoglycemic effect. The high productivity and bioactive effects are both great merits for Chinese yam peel polysaccharide as a promising candidate for foods and medicines industrial production.

Identification of Crucial Polymethoxyflavones Tangeretin and 3,5,6,7,8,3′,4′-Heptamethoxyflavone and Evaluation of Their Contribution to Anticancer Effects of Pericarpium Citri Reticulatae ‘Chachi’ during Storage

Pericarpium Citri Reticulatae ‘Chachi’ (PCR-C), rich in polymethoxyflavones (PMFs), has potential anticancer bioactivity and its quality will be improved during storage. However, the main factors influencing the PCR-C quality during its storage remain unclear. In this study, multivariate analysis was performed to investigate free and bound PMFs of PCR-C during storage. The anticancer effects of purified PCR-C flavonoid extracts (PCR-CF) and the important PMFs were evaluated using A549 cells. The results showed that PCR-C samples exhibited remarkable differences in free PMFs during storage, which fell into three clusters: Cluster 1 included fresh (fresh peel) and PCR-C01 (year 1); Cluster 2 consisted of PCR-C03 (year 3) and PCR-C05 (year 5); and PCR-C10 (year 10) was Cluster 3. 3,5,6,7,8,3′,4′-heptamethoxyflavone, tangeretin, and isosinensetin were identified as the most important PMFs distinguishing the various types of PCR-C according to its storage periods. Moreover, PCR-CF inhibited A549 cell proliferation and induced cell cycle arrest at G2/M phase, cell apoptosis, and ROS accumulation, and all anticancer indices had an upward tendency during storage. Additionally, tangeretin and 3,5,6,7,8,3′,4′-heptamethoxyflavone exhibited anticancer effects on A549 cells, whereas isosinensetin displayed no anticancer effect, indicating that tangeretin and 3,5,6,7,8,3′,4′-heptamethoxyflavone jointly contributed to anticancer activity of PCR-C during storage. PCR-CF and the most important PMFs killed cancer cells (A549 cells) but had no cytotoxicity to normal lung fibroblast cells (MRC-5 cells). Overall, the high quality of long-term stored PCR-C might be due to the anticancer effects of tangeretin and 3,5,6,7,8,3′,4′-heptamethoxyflavone.

Mechanism of Citri Reticulatae Pericarpium as an Anticancer Agent from the Perspective of Flavonoids: A Review

Citri Reticulatae Pericarpium (CRP), also known as “chenpi”, is the most common qi-regulating drug in traditional Chinese medicine. It is often used to treat cough and indigestion, but in recent years, it has been found to have multi-faceted anti-cancer effects. This article reviews the pharmacology of CRP and the mechanism of the action of flavonoids, the key components of CRP, against cancers including breast cancer, lung cancer, prostate cancer, hepatic carcinoma, gastric cancer, colorectal cancer, esophageal cancer, cervical cancer, bladder cancer and other cancers with a high diagnosis rate. Finally, the specific roles of CRP in important phenotypes such as cell proliferation, apoptosis, autophagy and migration–invasion in cancer were analyzed, and the possible prospects and deficiencies of CRP as an anticancer agent were evaluated.

Bioinformatics-Guided Identification of Ethyl Acetate Extract of Citri Reticulatae Pericarpium as a Functional Food Ingredient with Anti-Inflammatory Potential

Citri Reticulatae Pericarpium (CRP) is one of the most commonly used food supplements and folk medicines worldwide, and possesses cardiovascular, digestive, and respiratory protective effects partially through its antioxidant and anti-inflammatory functions. The unique aromatic flavor and mild side effects make CRP a promising candidate for the development of anti-inflammatory functional food. However, recent studies show that the crude alcoholic extract and some isolated compounds of CRP show compromised anti-inflammatory activity, which became the main factor hindering its further development. To identify the bioactive compounds with anti-inflammatory potential, and improve the anti-inflammatory effects of the extract, a bioinformatics-guided extraction protocol was employed in this study. The potential bioactive candidates were identified by combing network pharmacology analysis, molecular docking, principal components analysis, k-means clustering, and in vitro testing of reference compounds. Our results demonstrated that 66 compounds in CRP could be grouped into four clusters according to their docking score profile against 24 receptors, while the cluster containing flavonoids and phenols might possess a more promising anti-inflammatory function. In addition, in vitro anti-inflammatory tests of the seven reference compounds demonstrated that hesperitin, naringenin, and gardenin B, which were grouped into a cluster containing flavonoids and phenols, significantly decreased LPS-induced NO, TNF-α, and IL-6 production of macrophages. While the compounds outside of that cluster, such as neohesperidin, naringin, hesperidin, and sinensetin showed little effect on alleviating LPS-induced NO and proinflammatory cytokine production. Based on the chemical properties of selected compounds, ethyl acetate (EtOAc) was selected as the solvent for extraction, because of its promising solubility of flavonoids and phenols. Furthermore, the ethanol alcoholic extract was used as a reference. The chemical profiling of EtOAc and crude alcoholic extract by HPLC/MS/MS also demonstrated the decreased abundance of flavonoid glycosides in EtOAc extract but increased abundance of phenols, phenolic acid, and aglycones. In accordance with the prediction, the EtOAc extract of CRP, but not the crude alcoholic extract, significantly decreased the NO, IL-6, and TNF-α production. Taken together, the results suggested selective extraction of phenols and flavonoids rich extract was able to increase the anti-inflammatory potential of CRP partially because of the synergistic effects between flavonoids, phenols, and enriched polymethoxyflavones. Our study might pave the road for the development of ethyl acetate extract of CRP as a novel functional food with anti-inflammatory function.

SPME-GC-MS combined with chemometrics to assess the impact of fermentation time on the components, flavor, and function of Laoxianghuang

Laoxianghuang, fermented from Citrus medica L. var. Sarcodactylis Swingle of the Rutaceae family, is a medicinal food. The volatiles of Laoxianghuang fermented in different years were obtained by solid-phase microextraction combined with gas chromatography–mass spectrometry (SPME-GC–MS). Meanwhile, the evolution of its component-flavor function during the fermentation process was explored in depth by combining chemometrics and performance analyses. To extract the volatile compounds from Laoxianghuang, the fiber coating, extraction time, and desorption temperature were optimized in terms of the number and area of peaks. A polydimethylsiloxane/divinylbenzene (PDMS/DVB) with a thickness of 65 μm fiber, extraction time of 30 min, and desorption temperature of 200 °C were shown to be the optimal conditions. There were 42, 44, 52, 53, 53, and 52 volatiles identified in the 3rd, 5th, 8th, 10th, 15th, and 20th years of fermentation of Laoxianghuang, respectively. The relative contents were 97.87%, 98.50%, 98.77%, 98.85%, 99.08%, and 98.36%, respectively. Terpenes (mainly limonene, γ-terpinene and cymene) displayed the highest relative content and were positively correlated with the year of fermentation, followed by alcohols (mainly α-terpineol, β-terpinenol, and γ-terpineol), ketones (mainly cyclohexanone, D(+)-carvone and β-ionone), aldehydes (2-furaldehyde, 5-methylfurfural, and 1-nonanal), phenols (thymol, chlorothymol, and eugenol), esters (bornyl formate, citronellyl acetate, and neryl acetate), and ethers (n-octyl ether and anethole). Principal component analysis (PCA) and hierarchical cluster analysis (HCA) showed a closer relationship between the composition of Laoxianghuang with similar fermentation years of the same gradient (3rd-5th, 8th-10th, and 15th-20th). Partial least squares discriminant analysis (PLS-DA) VIP scores and PCA-biplot showed that α-terpineol, γ-terpinene, cymene, and limonene were the differential candidate biomarkers. Flavor analysis revealed that Laoxianghuang exhibited wood odor from the 3rd to the 10th year of fermentation, while herb odor appeared in the 15th and the 20th year. This study analyzed the changing pattern of the flavor and function of Laoxianghuang through the evolution of the composition, which provided a theoretical basis for further research on subsequent fermentation.

Multiple fingerprints and quantitative analysis for comprehensive quality evaluation of Citri reticulatae pericarpium within different storage years

The multi-wavelength fused HPLC fingerprint, and UV and DSC quantum fingerprints were used for quality evaluation of CRP by QRFM.