Aromatic Components Research Articles

Changes in Chemical Composition and Fatty Acid Profile of Milk and Cheese and Sensory Profile of Milk via Supplementation of Goats' Diet with Marine Algae.

The aim of the present study was to assess the effects of the low level of Schizochytrium limacinum marine algae (daily 5 g per animal) on the milk, cheese, and whey composition; fatty acid profile of milk and cheese; and the sensory profile of goat milk using an e-nose device. Thirty Alpine goats were randomly divided into two groups: the control group (C, n = 15)-fed grass with daily 600 g concentrate and the experimental group (MA, n = 15) who received the same forage and concentrate supplemented with 5 g/head/day marine algae. Animals were kept indoors and the investigation period lasted 52 days, including the first six weeks as the period of adaptation and the last 10 days as the treatment period. During the adaptation period, bulk milk samples from each group were collected once a week (0, 7, 14, 21, 28, 35, and 42 d), while during the treatment period (10 days), bulk milk samples from each group were taken every day, and cheese samples were processed from bulk milk each day from both groups. Marine algae supplementation had no negative effect on milk composition. In contrast, the marine algae inclusion significantly elevated the fat and protein content of whey and the protein content of cheese, as well as the recovery of fat and protein in the curd, while increasing the cheeses' moisture content on a fat-free basis. The marine algae supplementation significantly increased the docosahexaenoic acid (DHA) and the rumenic acid (CLA c9t11) concentrations and decreased the n-6/n-3 ratio in the milk and cheese. There were no significant differences between the C and the MA group with regard to the sensory profiles of the milk. It can be concluded that the milk obtained from goats given daily supplementation of 5g of MA has a fatty acid profile more beneficial to human health, without any negative effects on the milk's aromatic components.

Effect of the aqueous phase from the hydrothermal carbonization of sewage sludge as a moisture regulator on nitrogen retention and humification during chicken manure composting

The hydrothermal carbonation (HTC) of sewage sludge (SS) produces a large amount of an aqueous phase (AP), which has become a bottleneck for the development of HTC. Herein, the effectiveness of the AP from HTC as a moisture regulator for composting was investigated in terms of nitrogen (N) retention and humification. The AP from the HTC of SS (AP-SS) and that from the co-HTC of rice husks and SS (AP-RH–SS) were considered. Experimental results showed that AP-RH–SS and AP-SS reduced the cumulative ammonia emissions from compost by 41.74% and 9.98%, respectively; reduced the N losses by 36.68% and 14.91%, respectively; and increased the total N concentrations by 28.17% and 21.08%, respectively, compared with those from control treatment. AP-RH–SS and AP-SS promoted the humification process and considerably increased the humic content, humification index, and germination index of the compost products. Moreover, AP-SS and AP-RH–SS promoted the degradation of aliphatic proteins and increased the amount of unsaturated and aromatic components during composting while decreasing the average molecular weight of the dissolved organic matter in the compost products. These findings provide new insights into the design and implementation of joint management strategies for the AP and composting.

Mineral Additives Based on Industrial Waste for Modifications of Bitumen Polymers

The increase in cost of carbonaceous materials, as well as significant costs of industrial waste, have prompted scientists to use alternative raw materials as components of the construction industry. This study investigated the suitability of waste products from the coke industry as modifying agents for polymer bitumen. The by-product of the coking industry reaches a high level of silicon and is called silicon-containing additive (SCA), the composition of which is similar to the mineral solutions for bitumen. In this article, the results of using SCA as standard additives for modified polyethylene terephthalate (PET) with bitumen waste is presented. Using the Simdist boiling point distribution method, simulated high temperature distillation by gas chromatography, differential thermal (DTA) analyzes, and other methods of physic- chemical properties of bitumen after adding of SCA were studied. It was revealed that the connection and consumption of additives occurs because of the content of aromatic components, as well as an increase in the consumption of bitumen characteristics. Thus, the presented method for obtaining road surfaces based on PET waste and coke production waste meet the requirements of sustainable development, which implements both a significant use of industrial waste as secondary products and their processing into a new product using an energy-saving technology that reduces the consumption of raw materials and resources.

Identification and analysis of aromatic components in Piper sarmentosum Roxb. from Meru Betiri National Park

Piper sarmentosum Roxb or known as mana Karuk is an aromatic plant that has extraordinary potential, namely as a mucus expectorant, its roots are efficacious as a ureter and overcome gallstones. This plant is also used as an asthma drug, a cure for skin diseases such as tinea versicolor, stomach pain, malaria medicine, relieve bone pain and dental pain. The components of aromatic chemical compounds in the leaves and fruits from Meru Betiri National Park (MBNP) have not been identified. This study aimed to identify and analyze the aromatic components of P. sarmentosum leaves and fruits from MBNP using SPME-GCMS. The research method is laboratory research. The research samples and research materials were the leaves and fruit of the P. sarmentosum plant taken in MBNP. The SPME-GCMS tool is used in research to identify and analyze aromatic compounds. The research instrument used was an identification and analysis sheet of aromatic compounds from the P. sarmentosum plant. The data analysis technique uses the SPME-GCMS test. The results of the study showed that there were 46 volatile compounds found in the leaves, while in the fruit there were 29 volatile compounds. The main aromatic compound groups in the leaves and fruits of P. sarmentosum are terpenes, namely monoterpene. The other components consist of organic benzene compounds. P. sarmentosum Roxb. has 46 aromatic compounds in the leaves and 29 other aromatic compounds found in the fruit. Furthermore, research results must be tested in more depth regarding biological activity and mechanism of action through the best methods so that they can be recommended as new drug innovations in society.

POTENTIAL OF IMIDAZOLE-CONTAINING DERIVATIVES FOR PRACTICAL APPLICATION (Review)

The imidazole ring is becoming a popular structural fragment in synthetic pharmaceuticals, being an ionizing and aromatic component, which activates pharmacokinetic properties. The imidazole cycle is present in many antiprototic, antifungal and antihypertensive drugs, antibiotics and others. These structures are effective against various strains of microorganisms. The imidazole block is contained in the anticancer drug mercaptopurine, which has an effect by interfering with the DNA activity in the treatment of leukemia. Purpose: to review imidazole derivatives with various types of physiological and/or other actions published in the scientific literature over the last twenty years. Objects of research: imidazole derivatives. Results.An imidazole fragment is contained in a large number of natural products and clinically active drug molecules. Most of the publications relate to the study of the therapeutic possibilities of new structures of the class of imidazole derivatives for medical use. However, the potential of imidazole-containing molecules is not limited only to BAS, their other properties are interesting, in particular such one as corrosion inhibition. Conclusion: The introduction of a highly active imidazole fragment into an organic molecule stimulated the appearance of notable achievements in the field of chemotherapeutic and antibacterial agents. The active synthetic search for highly active imidazole compounds continues not only in the field of biologically active compounds, but also as the potential anticorrosiveand other agents.

Soil Organic Matter in Urban Areas of the Russian Arctic: A Review

Polar ecosystems are the most important storage and source of climatically active gases. Currently, natural biogeochemical processes of organic matter circulation in the soil-atmosphere system are disturbed in urban ecosystems of the cryolithozone. Urbanized ecosystems in the Arctic are extremely under-investigated in terms of their functions in regulating the cycle of climatically active gases. The role of urban soils and soil-like bodies in the sequestration and stabilization of organic matter is of particular interest. The percentage of gravimetric concentrations of organic matter in Arctic urban soils are almost always determined by the method of dichromate oxidation and are subject to extreme variability (from tenths of a percent to more than 90% in man-made soil formations), but the average carbon content in the surface soil horizons can be estimated at 5–7%. The surface humus-accumulative horizons are represented by a variety of morphological forms with the content of organic matter of various origins. The work also focuses on those forms of organic matter, the content of which is extremely small, but very important for the biogeochemical functioning of soils-polycyclic aromatic hydrocarbons and components of petroleum products, as well as labile forms of soil organic matter. We recommend that further studies of the organic matter system be conducted in urbanized areas since the carbon cycle there is severely disrupted, as well as carbon flows. The urbanization and industrialization processes in the Arctic are progressing, which could lead to a radical transformation of carbon ecosystem services.

Application of multiple ultra-high-pressure homogenization to the pasteurization process of Japanese rice wine, sake

Hiire is a pasteurization process in the production of Japanese rice wine (sake), which stabilizes the quality of product; however, it also generates the carcinogen ethyl carbamate (EC). In this study, we investigated the application of ultra-high-pressure homogenization (UHPH) as an alternative sterilization method for sake production. Microbiological analysis revealed that multiple UHPH treatments sterilized hiochi lactobacilli (Lactobacillus fructivorans, L. homohiochii, L. casei, and L. hilgardii) and Saccharomyces cerevisiae. Enzyme activity assays revealed that α-amylase, glucoamylase, and acid-carboxypeptidase activities were reduced to less than 1% of the levels in non-pasteurized sake after four-time UHPH treatment. These results show that UHPH treatment meets the two requirements of the sake sterilization process sterilization and enzyme inactivation. The UHPH-processed sake did not show any significant changes in general properties but had reduced organic acid and aromatic component contents, with ethyl caproate content showing the most significant reduction of approximately 20%. Interestingly, EC was detected in pasteurized sake but not in UHPH-processed sake. These findings indicate that the UHPH technology could be used to inactivate microorganisms and enzymes in sake without generating EC.

Bio-Modifier: A Sustainable Suturing Technology at the Bitumen–Aggregate Interface

Premature failure at the bitumen–aggregate interface is attributed to the surface chemistry of stone aggregates. Bitumen modifiers with high affinity toward aggregates are often used to change the surface chemistry of aggregates, which in turn changes the type and strength of stones’ interactions with bitumen. Here, the mechanisms of action and the effects of an organosilane and bio-oil separately on the bitumen–aggregate interface, including their binding to aggregates from one side and to bitumen from the other side, were studied and compared. The binding of bio-oils and organosilanes to aggregates is well documented, as well as their efficacy as anti-stripping agents, but their binding to bitumen is not well understood. Using glass beads as a surrogate for siliceous stones, we obtained laboratory measurements of interfacial strength as measured by resistance to shear forces at the interface of bitumen and silica. Our laboratory measurements showed the highest value for the bitumen modified with bio-oil, followed by the control bitumen with no modification, and the lowest value for the bitumen modified with organosilane. Our molecular modeling calculations showed that the adhesion of bitumen molecules to silica coated with bio-oil was notably stronger (up to 72%) than the adhesion of bitumen molecules to silica coated with organosilane. The higher interfacial strength observed for bitumen with bio-oil is attributed to bio-oil having various functional groups with the ability to form hydrogen bonds and π–π interactions with the aromatic and polar components of bitumen. The study outcomes highlight the importance of modifiers’ ability to strongly interact with both aggregates and bitumen. The bio-oil modifier introduced in this work can form a robust bridge between bitumen and siliceous aggregates to improve the adhesive properties, enhancing the sustainability and durability of bituminous composites.

The Effect of Microwave-Assisted Extraction Temperature and Material Ratio on the Characteristics of Pandan (Pandanus amaryllifolius Roxb.) Leaf Extract

Fresh pandan leaf fragrance has been applied to enhance the aroma of many traditional foods. However, the fresh leaf has a limited shelf life—only 1 day after harvest. Therefore, pandan extract, either in liquid or powdered form, can be utilized as an alternative aromatic component in food production. The purpose of this study was to determine the effect of extraction temperatures (50, 60, and 70°C) utilizing microwave-assisted extraction (MAE) and the ratio of pandan leaf as material to ethanol as solvent (1:3, 1:7, and 1:11) on the characteristics of pandan extract in liquid form. The study found that the properties of pandan extract treated at MAE 60°C with a material-solvent ratio of 1:7 were the best among all treatments. The pH of this liquid pandan extract was 5.31, the antioxidant activity was 32.86 ppm, and the chlorophyll content was 7.76 mg/L. The powdered pandan extract generated by drying the liquid pandan extract using a spray dryer and adding maltodextrin had properties such as water activity 0.45, solubility 96.09%, solubility rate 0.01 g/s, color L 85.65, a* -6.68, b* 8.51, yield 3.88%, and was detected to contain 0.17% of the aromatic compound 2-acetyl-1-pyrroline. Powdered pandan extract has the potential to be developed as an aromatic food additive. Panelists liked the kue lumpang, a traditional cake consisting mainly of rice flour and coconut milk, which is made by adding 1% pandan leaf extract powder.

Effect of Blending Aromatic and Oxygenates Additives with Fuels to Enhance Fuel Properties

This work aims to show the influence of several oxygenates and aromatic additives in different types of unleaded fuels in the Kurdistan region of Iraq on upgrading the physicochemical properties of blends. Consuming super-grade gasoline as a fuel for automotive cars can produce large amounts of environmental emissions, a severe global problem, especially in the Kurdistan region in recent years. The physicochemical properties of mixtures, such as the research octane number (RON), Motor Octane number (MON), density, and distillation curves, will be tested by using ERASPEC spectroscopy as a fuel properties analyzer. As a result, the blending process has improved the gasoline grade to super grade by enhancing the physicochemical properties of blends. The additives used in this work as oxygenators are; Ethanol and Methyl Tertiary Butyl Ether (MTBE) added to two base fuels, light Naphtha, and unleaded Gasoline, in various ratios of (5%, 10%, 15% and 20%). An aromatic component (Aniline) is also mixed with light Naphtha and base gasoline in low concentrations (1%, 3%, and 5%). The results of blending Ethanol, MTBE, and Aniline with fuels demonstrate that the Research Octane Number RON and Motor Octane Number MON of fuels increase with the addition of different ratios of all-octane boosters. The best-recorded result of both types of octane numbers (13 points increased from the bases) is recorded by blending 3% of Aniline with the fuels. However, Ethanol can provide a more significant increase in (RON) and (MON) than MTBE for the same blending ratio. The Density of the mixtures also increases because both additives have a higher density than the fuel due to the presence of different hydrocarbon compounds. The mixture's distillation curves are distorted, especially when the low to the middle percent of blenders are added to fuels. However, higher percentages of additives show lower distillation temperatures.

Effects of cyclic absorption–desorption of model fuels by aerospace‐grade carbon/epoxy composites

AbstractThe aviation industry is in the process of using several alternative fuels sourced from renewable sources to decrease its impact on the environment. These alternative fuels are mostly comprised of aliphatic hydrocarbons and have low to no aromatic content. The Federal Aviation Administration (FAA) has approved several drop‐in fuels, in which alternative fuels are typically blended with conventional Jet A fuel. Because of blending, the drop‐in fuels consist of both aliphatic and aromatic components. To achieve a fundamental understanding of how individual aliphatic and aromatic components interact with the aerospace‐grade composites, we have considered four model fuels, three aliphatic with varying chain lengths and one aromatic. The absorption of these model fuels by composites in three absorption/desorption cycles was captured and compared to the conventional Jet A fuel. The equilibrium weight gain by the composites due to absorption was low but was different for each model fuel, and the trend could be validated using Hansen solubility parameters. The absorption of model fuels decreased the glass transition temperature of composites. The change in glass transition temperature was not significantly different between the model fuels and the conventional fuel. These results can be translated to alternative fuels, making them a possible substitute for Jet A in the aviation industry.

Chemical tissue heterogeneity of young Arabidopsis stems revealed by Raman imaging combined with multivariate data analysis

Structural and chemical tissue heterogeneity in plant stems is essential to fulfil the many different functions for growth and survival. Cutting microsection of young developing stems of the model plant Arabidopsis opened the view on vascular bundles (transport of water, nutrients, food, and other chemicals), interfascicular fibers (mechanical support), parenchyma (production, storage) and the epidermis with cuticle (protection, barrier, exchange,..). Mapping such a cross-section with a Confocal Raman microscope resulted in hyperspectral datasets, which are the basis to image chemical heterogeneity with a spatial resolution of 300 nm in context with the microstructure. We generated the images based on three different multivariate approaches: unmixing to find the most pure components, cluster analysis so segment the dataset into clusters with spectral similarity, and fitting the original spectra at every pixel by a linear combination of plant component reference spectra. All three visualized chemical heterogeneity and confirmed in a complementary way the distribution of carbohydrates and aromatic components. The true component analysis was superior to cluster analysis in specificity and added information on lipids and starch distribution. Due to the multicomponent nature of plant tissues no “pure” components were retrieved, wherefore a subsequent mixture analysis (orthogonal matching pursuit) of extracted component spectra with a reference database followed. This led to details on the molecular composition of the spectra and tissues and was essential input for a final reference component fit at every pixel. By the last analysis, different aromatic components and hemicelluloses were discriminated and a similarity of their distribution patterns elucidated. Insights into starch and lipid distribution as well as the aromatic and protein co-location (mixtures) of cell contents were gained. The fit of the latter lumen content was inferior to the other fits due to noisier spectra (higher fluorescence background) and relevant protein and enzyme spectra were missing in our database. The gained comprehensive view on plant stem tissue heterogeneity showed the potential for future studies to unravel plant species characteristics and adaptations, but also to follow plant developmental processes and/or stress responses and/or genetic modifications.

Experimental Investigation of Naphthalene Induced Degradation of Reversible Solid Oxide Cells Operated on Bio-Syngas

The model tar Naphthalene is used to experimentally investigate the influence of polycyclic aromatic components on the performance of 10 x 10 cm² fuel-electrode supported solid oxide cells operated at artificial bio-syngas under internal reforming conditions. Two different fuel electrodes based on yttrium-stabilized zirconia (YSZ) and gadolinium-doped ceria (GDC) are investigated. A parameter study of the operational temperature and the operation mode is conducted with the YSZ based fuel electrode to quantify the effect on the degradation. The influence of the set-up is investigated by an experiment without the cell. The fuel off-gas composition as well as electrochemical impedance spectroscopy is used to characterize the cell prior to the experiment and to monitor its performance during the poisoning and regeneration process. The measurements are interpreted via the distribution of relaxation times.

Lignin and Its Bioconversion to Polyhydroxyalkanoates by the Bacterium Pseudomonas putida

Plant biomass is a very promising source of raw materials to produce sustainable fuels and chemicals otherwise derived from petroleum-based products. Part of plant biomass is lignin, which is one of the main natural sources of aromatic compounds. Although it is a large industrial by-product and a renewable carbon source, further processing into value-added products is currently limited. One of many applications of lignin under consideration is its bioconversion to polyhydroxyalkanoates, i.e., biodegradable polymers, which, due to their properties, could find their use in the fabrication of everyday products or in medicine and replace petroleum-based plastics in the future. They are produced by various bacteria in the form of intracellular granules but their industrial implementation is hindered by high production costs, which depend mainly on the price of the carbon source used for cultivation. Through the efficient bioconversion of lignin to polyhydroxyalkanoates, we could obtain environment-friendly and cost-effective biorefineries. However, to successfully bring the technology to an industrial scale, it is necessary to prepare a biological agent that will quickly and efficiently assimilate the aromatic components of lignin. The metabolically versatile bacterium Pseudomonas putida represents a promising candidate. Although it is a bacterium with lignolytic activity, the commercialization of the process requires further research on genetic and metabolic regulation and the preparation of a quality substrate, which depends on the source and the isolation process itself, and the success is unlikely to be achieved without good characterization and pretreatment of lignin.

ANALYSIS OF THE COMPOSITION AND STRUCTURE OF HEAVY OILS ACCORDING TO NMR SPECTROSCOPY

The results of studies of 1H and 13C NMR spectroscopy of heavy oil samples from the Timan Pechersk, Volga Ural oil and gas basins are presented. Knowledge of the chemical composition and physicochemical properties of crude oil, along with the particularities of geological and geochemical conditions is of paramount importance for solving the problems of the origin of crude oil and its subsequent processing. Information on the chemical composition of oil allows you to combine samples of crude oil from various fields before refining to achieve the necessary commercial and technical characteristics. 59.7-60.5% of β-CH3 groups were found in the samples, in β-CH2 and CH-groups to the aromatic ring, as well as the content of CH2- and CH-groups of saturated compounds. Dividing 13C NMR spectra into ranges shows a high content of methyl groups with the number of CH-groups in the alkyl fragments and CH and CH2-alkyl groups of naphthenic moieties attached to CH-group being 14.37-24.17%. A specific range of values is from 9.4 to 11.4 ppm. indicates methyl substituted octane, nonane or decane. It was found that the content of primary and secondary carbon atoms was in the range from 59.4-60.7%. The studied samples possess branched alkane chains. Comparison of the content of aromatic / aliphatic components allows us to determine the sample of the Volga Ural basin as a sample with a high content of aromatic component. The content of aromatic fragments varies in a wider range of 17-25.9%. From the data of 1H NMR-spectra of samples of heavy oils with different origin, viscosity and treatment it was found that crude and refined oils can differ in the content of olefin signals. For citation: Kolchina G.Yu., Poletaeva O.Yu., Leontev A.Yu., Movsumzade E.M., Loginova M.E., Kolchin A.V. Analysis of the composition and structure of heavy oils according to NMR spectroscopy. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2023. V. 66. N 6. P. 94-101. DOI: 10.6060/ivkkt.20236606.6783.

Catalyst-mediated pyrolysis of waste plastics: tuning yield, composition, and nature of pyrolysis oil

With ever-increasing plastic waste, a robust and sustainable methodology to valorize the waste and tweak, the composition of the value added product is the need of the hour. The present study describes the effect of different heterogeneous catalyst systems on the yield, composition and nature of the pyrolysis oil produced from various waste polyolefins like high-density polyethylene (HDPE), linear low-density polyethylene (LLDPE), and polypropylene (PP). The waste polyolefins were subjected to thermal as well as catalytic pyrolysis. Liquid, gas, and solid products were obtained during the pyrolysis. Various catalysts such as activated alumina (AAL), ZSM-5, FCC catalyst, and halloysite clay (HNT) were used. Usage of catalysts has reduced the temperature of the pyrolysis reaction from 470 to 450°C with better liquid product yield. PP waste generated higher liquid yield compared to LLDPE and HDPE waste. The highest liquid yield of 70.0% was achieved with PP waste using AAL catalyst at 450°C. The sulfur and chloride content was found to be < 10 and < 20ppm respectively in all the pyrolysis liquid. Pyrolysis liquid products were analyzed using gas chromatography (GC), nuclear magnetic resonance (NMR) spectroscopy, Fourier-transform infrared (FTIR) spectroscopy, X-ray fluorescence (XRF) spectroscopy, and gas chromatography coupled with mass spectrophotometry (GC-MS). The obtained liquid products consist of paraffin, naphthene, olefin and aromatic components. Catalyst regeneration experiments with AAL showed that the product distribution profile remains the same up to three cycles of regeneration.

Dissolved Organic Matter as Affected by Forms and Doses of Nitrogen Applied to Soils of Temperate Deciduous Forests in China

Dissolved organic matter (DOM) is an important component in the biogeochemical cycles of elements like nitrogen (N) and carbon. The aim of this study was to elucidate the effect of long-term inorganic N addition on the quantity and quality of DOM in forest soils. A field study was conducted on three forms of inorganic N, namely (NH4)2SO4, NH4NO3, and NaNO3, applied at low (50 kg N ha−1) or high (150 kg N ha−1) annual doses from 2011 to 2019. The total dose was split into eight equal monthly doses applied during the growing season (from March to October). Both the form and the dose increased the content of dissolved organic carbon (DOC) in soil, the strongest effect being that of NaNO3. However, the higher dose had a weaker effect because of N enrichment. UV-visible (UV-vis) and excitation-emission matrix (EEM) spectroscopy showed that the addition of N made DOM more aromatic and increased the degree of humification. EEM-parallel factor analysis (PARAFAC) modelling suggested that DOM in the forest soils mainly contained a fulvic-like constituent (C1), humic-like substances (C2), and aromatic protein-like components (C3). The addition did not change the position of the DOM fluorophore in the soil but affected the proportions of the three PARAFAC-derived components (increasing those of C1 and C2 but decreasing that of C3), indicating that long-term addition of N may amplify the decrease in protein-like constituents of surface soil. Hence, N addition increased the complexity of the DOM structure.

Response Characteristics of Soil Organic Carbon Pool and Its Chemical Composition During Secondary Forest Succession in the Loess Plateau

In order to explore the characteristics of the soil organic carbon(SOC)pool and its chemical composition during the succession of secondary forests in the Loess Plateau, samples of the primary stage (Populus davidiana forest), transition stage (Populus davidiana and Quercus wutaishansea mixed forest), and top stage (Quercus wutaishansea forest) of secondary forest succession in the Huanglong Mountain forest area of the Loess Plateau in Northern Shaanxi were selected as the research object. The variation characteristics of SOC content, storage, and its chemical composition at different soil depths (0-10, 10-20, 20-30, 30-50, and 50-100 cm) were analyzed. The results showed that:① the contents and storage of SOC increased significantly with the secondary forest succession process (P<0.05). The content of SOC decreased significantly with the increase in soil depth, and the storage of SOC increased from 64.8 Mg·hm-2 in the primary stage to 129.2 Mg·hm-2 in the top stage, with an increase of 99%. ② During the succession of secondary forests, in the surface (0-30 cm) soil organic carbon, the relative content of aliphatic carbon components that have a simple structure and can be decomposed more easily decreased, and the relative content of aromatic carbon components that have a complex structure and cannot be decomposed easily increased, indicating that the chemical composition of organic carbon stability of surface-layer soil increased significantly with the process of secondary forest succession. However, the stability of the chemical composition of SOC in the deep layer (30-100 cm) first increased and then decreased, that is, the transition stage>the top stage>the primary stage. ③In the process of secondary forest succession, the stability of SOC chemical composition in the primary stage and transition stage increased significantly with the increase in soil depth. The top stage tended to be stable, and the deep soil carbon stability decreased slightly. ④ Pearson correlation analysis showed that during the secondary forest succession process, SOC storage and chemical composition stability were significantly negatively correlated with soil total phosphorus content. In general, the content and storage of SOC in the 0-100 cm soil increased significantly during the secondary forest succession, playing the role of a "carbon sink." The stability of the chemical composition of SOC in the surface layer (0-30 cm) increased significantly, but in the deep layer (30-100 cm), it increased first and then decreased.

효소 및 미생물 복합체를 사용한 인비트로 루왁 커피의 품질 특성

In vitro luwak coffee was produced using enzyme-microbial complexes. The coffee quality of non-fermented coffee beans (NFC) and fermented coffee beans (FC) was compared. The total free amino acid content was higher in FC than in NFC. The levels of glutamic acid and γ-amino-n-butyric acid in NFC were higher than those in FC; however, the contents of essential amino acids, such as lysine, leucine, and valine, in FC were higher than in NFC. During fermentation, the sucrose content decreased, whereas the fructose and glucose contents increased (p&lt;0.001). The chromaticity of the coffee extract showed higher lightness (L), redness (a), and yellowness (b) values in FC than those in NFC. The caffeine content was significantly lower in FC (696.94±0.04 μg/mL) compared to that in NFC (1,130.22±1.55 μg/mL) (p&lt;0.001). Conversely, the polyphenol and chlorogenic acid contents were significantly higher ​​in NFC than in FC (p&lt;0.001). Electronic nose analysis indicated considerable differences between the volatile aromatic components in NFC and FC. Sensory scores were significantly higher for FC than those for NFC. Therefore, the fermentation of coffee beans using enzyme-microbial complexes altered the chemical components, which promoted the Maillard reaction during the coffee bean roasting process. These results suggest the possibility of producing in vitro luwak coffee with better flavor and lower caffeine content.

효소 및 미생물 복합체를 사용한 인비트로 루왁 커피의 품질 특성

In vitro luwak coffee was produced using enzyme-microbial complexes. The coffee quality of non-fermented coffee beans (NFC) and fermented coffee beans (FC) was compared. The total free amino acid content was higher in FC than in NFC. The levels of glutamic acid and γ-amino-n-butyric acid in NFC were higher than those in FC; however, the contents of essential amino acids, such as lysine, leucine, and valine, in FC were higher than in NFC. During fermentation, the sucrose content decreased, whereas the fructose and glucose contents increased (p&lt;0.001). The chromaticity of the coffee extract showed higher lightness (L), redness (a), and yellowness (b) values in FC than those in NFC. The caffeine content was significantly lower in FC (696.94±0.04 μg/mL) compared to that in NFC (1,130.22±1.55 μg/mL) (p&lt;0.001). Conversely, the polyphenol and chlorogenic acid contents were significantly higher ​​in NFC than in FC (p&lt;0.001). Electronic nose analysis indicated considerable differences between the volatile aromatic components in NFC and FC. Sensory scores were significantly higher for FC than those for NFC. Therefore, the fermentation of coffee beans using enzyme-microbial complexes altered the chemical components, which promoted the Maillard reaction during the coffee bean roasting process. These results suggest the possibility of producing in vitro luwak coffee with better flavor and lower caffeine content.