Search Results (106)

The evaluation of aroma-active profiles in dry-cured hams is crucial for determining quality, flavor, consumer acceptance, and economic value. This study characterized the volatile compounds in five varieties of dry-cured hams using gas chromatography-mass spectrometry-olfactometry (GC-MS-O) and an electronic nose (E-Nose). In total, 78 volatile compounds were identified across five varieties of dry-cured hams. A total of 29 compounds were recognized as aroma-active compounds. Odor description, intensity, and hedonic assessment were employed to evaluate these compounds. Black Hoof Cured Ham and Special-grade Xuan-Zi Ham contained higher levels of favorable compounds such as nonanal, 5-butyldihydro-2(3H)-furanone, and 2,6-dimethylpyrazine, contributing to sweet and popcorn-like notes. In contrast, Fei-Zhong-Wang Ham and Liang-Tou-Wu Ham exhibited higher proportions of off-odor compounds with lower hedonic scores. A principal component analysis clearly separated the five hams based on their aroma-active profiles, and a correlation analysis between E-Nose sensor responses and GC-MS-O data demonstrated a strong discriminatory ability for specific samples. These findings offer valuable insights into the chemical and sensory differentiation of dry-cured hams and provide a scientific basis for quality control, product development, and future improvements in E-Nose sensor design and intelligent aroma assessment. Full article

The characteristic minty-like aroma of ‘Rucheng Baimaocha’ black tea (RCBT) enhances the tea’s unique flavor profile, driving high demand among consumers. The dynamic changes in key aroma compounds in minty-like RCBT were elucidated by sensory evaluation and gas chromatography olfactometry quadrupole time of flight mass spectrometry (GC × GC-O-Q-TOF-MS). The results indicated that during processing, the aroma of RCBT transitions from a fresh to floral, sweet, and minty-like aroma. Among the 189 identified volatile compounds, alcohols constitute the predominant category (over 50%), with 71 compounds identified as key differential compounds across all stages. Aroma analysis revealed that 28 compounds with odor activity values (OAV) > 1 were the primary contributors during RCBT processing. Notably, minty-like odorants in RCBT were primarily derived from the metabolic pathways of the methylerythritol phosphate (MEP) and mevalonic acid (MVA), lipid oxidation, and phenylalanine. These findings offer theoretical insights for improving unique black tea quality and optimizing processing techniques. Full article

China is the place of origin and main producer of black tea worldwide, with Dianhong (DH), Chuanhong (CH), and Keemunhong (KH) being the famous Chinese black teas. The contents of various odor components in black teas differ with their origins. However, the effects of these differences on the presentation of distinctive odor characteristics in various products remain unclear. We aimed to elucidate the odor characteristics and odor compounds of these three black teas; to this end, we performed a sensory evaluation and multivariate statistical analysis based on comprehensive two-dimensional gas chromatography–mass spectrometry (GC×GC-MS) results. The sensory evaluation revealed that the odor characteristics of DH were floral and fruity, whereas sweet and herbal-like odors were more intense in CH and QH. A total of 119 volatile compounds were detected, with alcohols, aldehydes, and esters being the main volatile compounds. Among them, 41 volatile compounds were identified with an odor activity value (OAV) of >1, and 24 of them were selected through principal component analysis, hierarchical cluster analysis, and orthogonal partial least squares discriminant analysis as marker substances to distinguish the three teas; thus, 24 volatile compounds are important odor compounds of DH, CH, and QH. Full article

Currants are highly valued nutritionally and are traditionally grown in the Czech Republic. This study investigated 15 cultivars of red, white, and black currants to better understand their positive sensory properties and their relationship to consumer preference. Red and white cultivars, in particular, have received little attention from this perspective. Sensory quality, primarily flavor, was evaluated in conjunction with volatile compound profiling to identify the sensorially superior cultivars. The results confirmed clear differences between black currants and red/white variants. Red and white currants, belonging to the same species (Ribes rubrum), exhibited similar volatile compound content and composition, as well as similar sensory characteristics, distinguishing them significantly from black currants (Ribes nigrum). The flavor of black currants, characterized by strong astringency and distinct blackcurrant notes, was generally perceived less favorably by the evaluators. A total of 54 volatile compounds were identified across the analyzed cultivars. Alcohols (contributing flowery and fruity aromas), aldehydes (grassy aromas), and esters (fruity aromas) were the most abundant in most cultivars. Using the odor activity value (OAV) concept, 15 of these compounds were identified as likely contributors to currant flavor (OAV ≥ 1). Principal component analysis (PCA) identified the top cultivars within each variant: ‘Victoria’ (white), ‘Rubigo’ (red), and ‘Demon’ (black). These are proposed for potential practical applications. Full article

This study enhanced the odor retention of instant black tea powder by utilizing ultrasonic-assisted extraction and β-cyclodextrin embedding technology. Through single-factor tests considering variables such as the tea-to-water ratio, extraction temperature, ultrasonic extraction duration, and β-cyclodextrin addition, the optimal extraction conditions were determined. The ideal parameters were identified as follows: β-cyclodextrin was added at a rate of 7.5%, the tea-to-water ratio was 1:16, the ultrasonic extraction temperature was 52 °C, and the extraction duration was 30 min, and then the extract was processed by freeze-drying to obtain instant tea powder. Electronic nose trials revealed that the primary volatile odor compounds distinguishing the 14 groups of instant black tea soups were sulfides, terpenes, nitrogen oxides, alkanes, and aromatic compounds. HS-SPME-GC-MS analysis identified 65 effective volatile compounds, among which 11 key odor compounds, including Benzyl alcohol, Phytol, phenylethyl alcohol, 1,6,10-Dodecatrien-3-ol,3,7,11-trimethyl-,(E)-, Benzeneacetaldehyde, Undecanoic acid, ethyl ester, Dodecanoic acid, ethyl ester, Tetradecane, 2,4-Di-tert-butylphenol, 2-Pentadecanone, 6,10,14-trimethyl-, and indole, were the main contributors to the odor profile of instant black tea. The instant black tea powder produced under these conditions exhibited high quality, providing a valuable reference for further research on the production process of instant black tea powder. Full article

Spices are a part of modern and ancient cultures due to their recognized culinary and medicinal properties. Pepper is commonly used in many recipes; however, in the field of gastronomy, the term “pepper” usually refers to a group that includes several different spices, such as black pepper (Piper nigrum L.), cubeb pepper (Piper cubeba L.f.), long pepper (Piper longum L.), pink pepper (Schinus terebinthifolius Raddi), allspice (Pimenta dioica L. Merrill), and Japanese pepper (Zanthoxylum piperitum DC.). Despite the extensive study of the chemical characterization and medicinal and culinary properties of “pepper”, sensory analysis (color, aroma profile, odor profile, and chemesthesis) of these spices have not been completed. Therefore, the aim of this review was to identify the strengths, weaknesses, opportunities, and threats within the spice supply chain considering these six “peppers” to analyze their positive and negative aspects. Finally, we selected the most representative molecules and properties of spices referred to as “pepper” to expand the research focus and highlight their key aspects related to health and sensory science for future applications. In this sense, this review provides a new strategic guideline that will help us understand and assess the key internal and external factors of pepper, allowing them to be applied in different sectors with different approaches. Full article

Dixu tea is one of the characteristic tea germplasm resources of southeastern Yunnan, and is also a precious wild tea germplasm resource. Background: In order to further develop Dixu tea products and improve their flavor, this article studies the effects of different processing methods on the aroma quality of Dixu tea. Methods: A comprehensive analysis of the aroma quality of Diwei tea was conducted using HS-SPME combined with GC-MS and multivariate statistical analysis. A principal component analysis (PCA) was applied to process the detected volatile substances and an orthogonal partial least squares-discriminant analysis (OPLS-DA) model was established. We evaluated the contribution of major compounds in the tea aroma by calculating the odor activity value (OAV). Results: The results showed that a total of 67 compounds were identified. A total of 27 major aromatic volatile compounds (OAV > 1) were screened, and 17 key differential volatile compounds were identified in different tea samples, including octanoic acid, d-citrol, laurene, hexanal, citral, β-cyclic citral, trans-2-hexenal, γ-nonanolide, β-ionone, geranylacetone, 1,1,6-trimethyl-1,2-dihydronaphthalene, geraniol, methyl salicylate, linalool, nerolidol, and 7,11-dimethyl-3-methylene-1,6,10-dodecatriene. Combined with the OAV analysis, it is shown that a floral fragrance is a common feature of Guangnan Dixu tea varieties. In addition, white tea also has a fragrant aroma, while black tea, green tea, and bamboo tube tea are all accompanied by a fruity aroma. Conclusions: In summary, processing techniques regulate the aroma characteristics of various types of tea by changing the types and contents of volatile aroma compounds. This provides a theoretical basis for exploring and utilizing tea production resources in the future. Full article

The application of shaking during the withering process has been shown to significantly enhance the floral aroma of black tea. However, prior to this study, there was limited research on the effects of shaking combined with other withering treatments on the aroma components of black tea. In this study, the aroma attributes of black teas processed with shaking combinations of yellow-light or high-temperature withering (YLS, HTS, and HYS) were evaluated through sensory evaluation, and the volatile composition and identification of key aroma compounds in black teas and in-process withered tea leaves were analyzed by gas chromatography–mass spectrometry (GC-MS). The results indicated that black teas subjected to different shaking combinations exhibited a distinct floral aroma with higher volatile compound content, with the YLS treatment showing the most significant aroma improvement. Eight volatile compounds with relative odor activity values (rOAV) > 1 were identified from 53 differential volatile compounds in black tea under different shaking combinations as the most important contributors to aroma quality. Linalool, trans-β-Ionone, α-cedrene, and nonanal were identified as key floral volatiles with high rOAVs. Their concentrations in YLS were notably higher compared to those in S, both in withered tea leaves (with the exception of trans-β-Ionone) and in the final dry black teas, suggesting that there may be a synergistic effect between the yellow-light withering and the shaking process in enhancing these key floral compounds. Overall, this study found that shaking combined with yellow-light withering can improve the aroma composition and quality of black tea, providing a theoretical basis and practical guidance for the production and optimization of high-aroma black tea. Full article

Black-odorous water (BOW) in urban areas poses significant risks to water safety and human health. Chemical oxygen demand (COD) is a critical parameter for the control and monitoring of BOW. However, traditional methods for COD determination are expensive, time-consuming, and involve the use of hazardous chemicals. In this study, reduced graphene oxide (rGO) and transitional metal particles (Cu, Ni) were used as working electrode materials for facile on-site determination of COD in BOW. Three composite materials (rGO/Cu, rGO/Ni, and rGO/Cu/Ni) were synthesized by one-step chemical reduction with different ratios, and their microstructure and chemical composition were characterized. Glucose solution and real water were used to evaluate the electrocatalytic performance of the different sensors. The ternary composite (rGO/Cu/Ni) screen-printed electrode sensor demonstrated excellent performance in COD analysis, with a low limit of detection (18.9 mg L⁻¹), a broad linear detection range from 53 to 1500 mg L⁻¹, and a 1.61% relative error for real water samples. The testing results were highly consistent with those obtained using the standard chromium sulfate method. This study offers promising prospects for the mass production of cost-effective COD electrochemical sensors, facilitating real-time, on-site monitoring of water bodies in major urban areas. Full article

Poultry litter waste management poses a significant global challenge, attributed to its characteristics (odorous, organic, pathogenic, attracting flies). Conventional approaches to managing poultry litter involve composting, biogas generation, or direct field application. Recently, there has been a surge of interest in a novel technology that involves the bioconversion of organic waste utilizing insects (known as entomoremediation), particularly focusing on black soldier fly larvae (BSFL), and has demonstrated successful transformation of various organic waste materials into insect meal and frass (referred to as organic frasstilizer). Black soldier flies have the capacity to consume any organic waste material (ranging from livestock litter, food scraps, fruit and vegetable residues, sewage, sludge, municipal solid waste, carcasses, and defatted seed meal) and convert it into valuable BSFL insect meal (suitable for animal feed) and frass (serving as an organic fertilizer). The bioconversion of poultry litter by black soldier flies offers numerous advantages over traditional methods, notably in terms of reduced land and water requirements, lower emissions, cost-effectiveness, swift processing, and the production of both animal feeds and organic fertilizers. This review focuses on the existing knowledge of BSFL, their potential in bioconverting poultry litter into BSFL meal and frass, and the utilization of BSFL in poultry nutrition, emphasizing the necessity for further innovation to enhance this sustainable circular economy approach. Full article

To explore the effects of different withering methods on the quality of Congou black tea, this study focused on five different withering methods: natural withering, warm-air withering, sun–natural combined withering, sun withering, and shaking withering. Gas chromatography‒mass spectrometry (GC‒MS), high-performance liquid chromatography (HPLC), and ion-exchange chromatography techniques were used to analyze the nonvolatile and volatile components and composition of the tea. The results revealed significant differences (p < 0.05) in the contents of nonvolatile constituents including caffeine, polyphenols, soluble sugars, free amino acids and their components, theaflavins, thearubigins, and catechins among the five different withering methods, with varying degrees of correlation between these components. A total of 227 aroma compounds were detected, and significant differences in the contents of alcohols, aldehydes, and ketones were observed. A relative odor activity value (ROVA) analysis of the aroma compounds revealed that 19 compounds had an ROVA > 1. Among them, benzylaldehyde, trans-2-decenal, decanal, benzaldehyde, nonanal, hexanal, trans-linalool, and geraniol from the shaking withering method had significantly higher ROVA values than those from the other withering methods, which may be the reason for the prominent floral and fruity aroma of shaking withering. This study revealed the impact of different withering methods on the quality of Congou black tea, providing a scientific basis for the development of Congou black tea with different flavors and the improvement of Congou black tea processing techniques. Full article

Tea standard samples are the benchmark for tea product quality control. Understanding the inherent differences in Chinese national standards for Lapsang Souchong black tea of different grades is crucial for the scientific development of tea standardization work. In this study, Lapsang Souchong black tea of different grades that meet Chinese national standards was selected as the research object. The aroma characteristics were comprehensively analyzed through sensory evaluation, electronic nose, and HS-SPME-GC-MS (headspace solid-phase microextraction gas chromatography–mass spectrometry). The findings indicate that the higher-grade Lapsang Souchong has a higher evaluation score. The results of electronic nose analysis indicate that the volatiles with differences in tea of different grades were mainly terpenoids and nitrogen oxides. The results of HS-SPME-GC-MS analysis show that the odor characteristics of the super-grade samples are mainly floral and fruity, and these substances mainly include D-Limonene, 3,7-dimethyl-1,6-octadien-3-ol and 3-Hydroxymandelic acid, and ethyl ester. The primary aroma characteristics of the first-grade samples are floral, sweet, woody, and green, with key contributing compounds including 2-Furanmethanol, 1-Octen-3-ol, and 5-ethenyltetrahydro-α,α,5-trimethyl-cis-, 4,5-di-epi-aristolochene. The main aroma characteristics of the second-grade samples are green, herbal scent, and fruity, and the main substances include 3,7-dimethyl-1,6-octadien-3-ol, 2,3-dimethylthiophene, Dihydroactinidiolide, and Naphthalene-1-methyl-7-(1-methylethyl)-. It is worth noting that the second-grade samples contain a large amount of phenolic substances, which are related to the smoking process during processing. This study lays a solid foundation for the preparation of tea standard samples and the construction of the tea standard system. Full article

Huangjinya has recently seen widespread adoption in key tea-producing areas of China, celebrated for its unique varietal traits. Its leaves are also used to produce black tea with distinctive sensory characteristics. The fragrance-enhancing (EF) process is essential in crafting Huangjinya black tea (HJYBT) and is significant in flavor development. However, the impact of EF on non-volatile metabolites (NVMs), volatile metabolites (VMs), and their interactions remains poorly understood. This study aims to investigate how EF temperatures (60 °C, 70 °C, 80 °C, 90 °C, and 110 °C) influence HJYBT flavor transformation. Quantitative descriptive analysis revealed that EF improved the color, aroma, and appearance of tea leaves. Moreover, after an EF temperature of 80 °C, the HJYBT exhibited lower bitterness and astringency, whereas floral, sweet, and fruity aromas became stronger. However, when EF temperatures exceeded 90 °C, a pronounced burnt aroma developed, with HJYBT at 100 °C exhibiting caramel and roasted notes. Partial least squares discriminant analysis indicated that geraniol and linalool contribute to floral and fruity aromas, while 2-ethyl-6-methyl-pyrazine, furfural, and myrcene are key volatiles for caramel and roast aromas. Heptanal, methyl salicylate, α-citral, 1-hexanol, and (E)-3-hexen-1-ol were found to modify the green and grassy odor. Overall, HJYBT treated at 80 °C EF exhibited the highest umami, sweetness, floral and fruity aromas, and overall taste, exhibiting the least astringency, bitterness, and green and grassy notes. These results provide a significant theoretical basis for enhancing HJYBT quality and selecting the optimal EF method. Full article

Black-odor water, which is caused by the excessive accumulation of nitrogen and phosphorus in water, is a significant problem. Immobilized microorganisms are considered to be an effective technical solution, but there are still many key parameters to be determined, such as organic matter dissolution, insufficient stability, and insufficient phosphorus removal capacity, among other problems. In this study, the optimum raw material ratios of immobilized microorganism gel beads were determined by means of a response surface experiment. The optimal ratio of raw materials was 5% polyvinyl alcohol (PVA), 1% sodium alginate (SA), and 6% bacterial powder. In addition, the nitrogen and phosphorus removal performance of the materials was improved by loading inorganic compounds, such as 0.5 wt.% zeolite, 0.5 wt.% iron powder, and 0.2 wt.% activated carbon. Tolerance analysis determined that these gel beads could maintain a good performance in a series of harsh environments, such as during intense agitation, at high temperatures, and at low pH values, etc. The total nitrogen (TN), ammonia nitrogen (NH₃-N), and phosphorus (TP) removal efficiencies were 88.9%, 90%, and 95%. Full article

In recent years, the phenomenon of black–odorous water has occurred frequently, and constructed wetlands have been widely used as an effective means of treating black–odorous water. In order to achieve the goal of low-carbon and high-efficiency long-term clean-up of black–odorous water, the modular constructed wetland system was optimized in this study. The optimized modular constructed wetland consisted of aeration, denitrification, and phosphorus removal, of which the denitrification module was a sulfur–iron autotrophic denitrification unit and the phosphorus removal module was a polyaluminum chloride composite filler phosphorus-removal unit. Experimental findings indicated that modular systems with layout ratios of 1:3:1 (A) and 1:2:2 (B) exhibit outstanding performance in remediating contaminants from black–odorous water. Notably, system B demonstrated superior treatment efficiency. Under conditions of high pollution loading, system B consistently achieved stable removal rates for COD (95.79%), TN (91.74%), NH₄⁺-N (95.17%), and TP (82.21%). The combination of along-track changes and high-throughput sequencing results showed that the synergies among the units did not produce negative effects during the purification process, and each unit realized its predefined function. Changes in the substrate and internal environment of the wetland units caused changes in the microbial populations, and the unique microbial community structure of the units ensured that they were effective in removing different pollutants. Full article