Thermolabile Components Research Articles

PRINCIPLES OF SIMULATION OF ENERGY-EFFICIENT GRANULATION PROCESSES IN A FLUIDIZED BED

The principles of physical and mathematical modeling of inhomogeneous jet-pulsating fluidization in the self-oscillating mode considering the movement of solid granulated particles on the working surfaces of the gas distributing device are investigated. The research tasks include substantiating the method of interaction between the gas phase and granular solids to ensure the implementation of heterogeneous jet-pulsating fluidization in the self-oscillating mode, experimentally determining hydrodynamic parameters to minimize the risk of stagnant zones on the working surface of the gas distributing device and formulating principles for introducing flat gas jets into orthogonal planes through a gas distribution device. The physical model focuses on creating heterogeneous jet-pulsating fluidization which is based on the formation of heterogeneous porosity in the bed of solids within the apparatus chamber. The study highlights the importance of rationally organizing the interaction mode between the gas phase and solids to ensure active circulation of granular material between 3 main technological zones: humidification, active heat exchange and relaxation. This organization enables sufficient mass transfer along the height of the bed and getting a product with the desired properties. Implementing the proposed modeling principles in equipment development will allow increasing the heat utilization coefficient by more than 60 % and will facilitate the implementation of innovative technology. The research contributes to the development of fluidization technology and its application in granulation at temperatures exceeding the melting point of thermolabile components, ensuring efficient use of resources and energy, and enhancing the environmental safety of technological processes. Bibl. 22, Fig. 11.

Alteration of Organic Matter during Wildfires in the Forests of Southern Siberia

Large areas of forests burn annually in Siberia. Pyrogenic organic matter (PyOM) generated by wildfires acts as a stable carbon deposit and plays an important role in the global carbon cycle. Little is known about the properties of PyOM formed during fires in Siberian forests. In this work, we report the results of thermogravimetry (TG), differential scanning calorimetry (DSC), and Fourier transform infrared (FTIR) spectroscopy applied to the study of the chemical composition, structure, and thermal stability of PyOM formed during surface and crown fires of moderate to high severity in southern Siberia. We studied the PyOM produced from the forest floor, down wood, cones, and outer bark of tree stems in Scots pine, larch, spruce, and birch forests. We calculated the thermal recalcitrance indexes (R50, Q3) based on TG/DSC data. We found that wildfires resulted in a strong decrease in thermolabile components in burned fuels, enrichment by aromatic structures, and a significant increase in thermal stability (T50) compared to unburned samples. In all the studied forests, bark PyOM revealed the highest value of T50 while forest floor PyOM had the lowest one. At the same time, our results indicated that the properties of PyOM were more strongly driven by wildfire severity than by fuel type. Overall, the thermal recalcitrance R50 index for PyOM samples increased by 9–29% compared to unburned plant residues, indicating a shift from low to intermediate carbon sequestration potential class in the majority of cases and hence less susceptibility of PyOM to biodegradation.

Spent Pleurotus ostreatus Substrate Has Potential for Managing Fusarium Wilt of Banana.

A range of basidiomycetes including the edible mushroom Pleurotus ostreatus (Po) can suppress plant pathogens such as Fusarium spp. With the current increase in production and consumption of Po in Uganda, the spent Po substrate (SPoS) could be an alternative to manage Fusarium wilt of banana (FWB), caused by the soil borne pathogen Fusarium oxysporum f. sp. cubense, race 1 (Foc). This study determined the potential of SPoS to inhibit Foc in vitro and in potted plants. In vitro studies confirmed suppression of Foc in pure co-culture (Po vs. Foc) assays and media amended with different concentrations (0% to 50% w/v) of un-sterilized SPoS filtrates. Foc growth in the sterile SPoS filtrate was comparable to the water control, suggesting possible roles of biotic or thermolabile components of the SPoS. To further verify the suppressive effects of SPoS, pot experiments were carried out with a resistant (‘Mbwazirume’, AAA) and susceptible (‘Sukali Ndizi’, AAB) banana cultivar using both artificially and naturally infested soils. Independent of the inoculation method, SPoS significantly reduced the severity of FWB in pot experiments. Susceptible cultivar ‘Sukali Ndizi’ growing in substrates amended with SPoS showed lower (1.25) corm damage (Scale 0–5) than the un-amended control (3.75). No corm damage was observed in uninoculated controls. The resistant cultivar ‘Mbwazirume’, showed slight (0.25) corm damage only in the Foc-inoculated plants without SPoS. These findings suggest that SPoS could be used as part of the management practices to reduce the impact of FWB.

Blueberry juice: Bioactive compounds, health impact, and concentration technologies-A review.

Blueberries are a popular fruit with an attractive flavor and color, as well as health benefits. These health benefits have been attributed to the important number of bioactive compounds in blueberries with activities such as antioxidant, antitumor, antimutagenic, and antidiabetic effects and the prevention of cardiovascular diseases. Despite these advantages, blueberries are only obtained fresh in certain seasons; therefore, the food and beverage industry transforms them into jelly, puree, or juice. However, the concentration process could help preserve the bioactive compounds of blueberry byproducts. Concentration technologies focus on the removal of excess water to increase the product stability and reduce storage and transportation costs by causing them to take up less space or as a pretreatment before dehydration. These technologies include evaporation, reverse osmosis, and freeze concentration, and each one has different effects on the efficiency, quality, and nutritional value of the final concentrates. However, freeze concentration and reverse osmosis produce a higher-final quality concentrate than evaporation due to the use of low temperatures, which prevents the loss of thermolabile components such as bioactive compounds. Therefore, this review summarizes the impact of concentration technologies on the bioactive compounds and health benefits of blueberry juice.

Portfolio of beetroot (Beta vulgaris L.) peel extracts concentrated by nanofiltration membrane

Membrane process is an intelligent alternative way of concentration, preferably for organic juices rich in thermolabile natural components. The expectation is to scale up the extraction of desired compounds from agro-industrial wastes through modernized concentration method. Recovery of betalains, phenolic, and antioxidant from beetroot peel extracts was accomplished by nanofiltration membrane (NF 200) at a recirculation flow rate (400 L h-1) and feed temperature (30 ºC) under constant transmembrane pressure (40 bar). Characterization of betaxanthin, betacyanin, phenolic, and antioxidant activity by spectrophotometric analysis revealed that the final samples contain these compounds respectively: 202.25±3.26 mg.L-1, 360.07±8.43 mg.L-1, 987.79±19.18 mg.L-1, 642.06±14.78 mg.L-1 (pure water); 206.62±1.37 mg.L-1, 339.72±2.89 mg.L-1, 972.72±47.49 mg.L-1, 745.97±25.45 mg.L-1 (ethanol-water). Final samples exhibit vivid colour and a considerably large amount of desired compounds compared to crude extracts and could have industrial applications.

Conventional and emergent technologies for honey processing: A perspective on microbiological safety, bioactivity, and quality.

Honey is a natural food of worldwide economic importance. Over the last decades, its potential for food, medical, cosmetical, and biotechnological applications has been widely explored. One of the major safety issues regarding such applications is its susceptibility to being contaminated with bacterial and fungi spores, including pathogenic ones, which may impose a hurdle to its consumption in a raw state. Another factor that makes this product particularly challenging relies on its high sugar content, which will lead to the formation of hydroxymethylfurfural (HMF) when heated (due to Maillard reactions). Moreover, honey's bioactivity is known to be affected when it goes through thermal processing due to its unstable and thermolabile components. Therefore, proper food processing methodologies are of utmost importance not only to ensure honey safety but also to provide a high-quality product with low content of HMF and preserved biological properties. As so, emerging food processing technologies have been employed to improve the safety and quality of raw honey, allowing, for example, to reduce/avoid the exposure time to high processing temperatures, with consequent impact on the formation of HMF. This review aims to gather the literature available regarding the use of conventional and emergent food processing technologies (both thermal and nonthermal food processing technologies) for honey decontamination, preservation/enhancement of honey biological activity, as well as the sensorial attributes.

Імуномоделюючі соуси

Deficiency of most micronutrients, imbalance in nutrition, together with a dangerous environmental situation in Ukraine, has led to a decrease in the immunity of the population and the spread of alimentary-dependent diseases. Due to the damaged immunological picture of the population in recent years, the relevance of the creation of immunomodulating products is significantly increasing. About 70% of dishes served in restaurant are released with sauces, which allows not only to improve the aroma, appearance and taste of the finished dish, but also to increase the content of the essential substances of the dish. In the assortment of sauce products on the Ukrainian market, most of the sauces contain preservatives, artificial stabilizers and emulsifiers that negatively affect the human body and are not recommended for daily consumption. The subject of research is sauce products for preventive nutrition with increased nutritional value, without the presence of artificial food additives in the composition. The purpose of the study is to develop formulations of immunomodulating sauces using natural raw materials. Methods. The object of the study - developed immunomodulating sauces. In the finished product, the following parameters were determined: titratable acidity (DSTU 4957:2008), microbiological indicators (GOST 10444.15-94, GOST 54728-92, GOST 10444.2-94, GOST 30519-97). The results of the study. As a result of a literature search, the substances were determined, their bigger content in dies being important for improvement in the state of the immune system. These substances include, first of all, antioxidant vitamins (C, A and E), polyunsaturated fatty acids (especially omega-3), mineral elements and other minor substances. During developing the formulations of immunomodulating sauces, twelve requirements were formulated.. As a result of the raw materials selection, three formulations of immunomodulating sauces have been proposed. In their technology, there is a high-temperature heat treatment, which allows maximizing the preservation of useful thermolabile components. Scope of research results. Ready-made sauces are sold in restaurant establishments and consumed locally. Due to their simplicity of preparation, they can also be recommended for making at home. The developed immunomodulating sauces have a pleasant appearance and harmonious taste, which is confirming the data of sugar-acid indices.

Leaf essential oil from Ivorian Isolona dewevrei (Annonaceae): Chemical composition and structure elucidation of four new natural sesquiterpenes

AbstractThis work is a contribution to the characterization of aromatic and medicinal plants from Côte d’Ivoire. To date, no phytochemical investigation was reported on Isolona dewevrei. Thus, the aim of this study was to investigate for the first time, the chemical composition of the leaf essential oil from I dewevrei. Two essential oil samples (S1, S2) were analysed by combination of chromatographic [GC(FID) and GC(RI)] and spectroscopic [MS, 13C‐NMR] techniques. As several compounds remained unidentified, particularly in sample S1, this oil was fractionated on silica gel column, leading to the isolation and structural elucidation of four new natural compounds by QTOF‐MS, 1D and 2D‐NMR analyses. These new natural sesquiterpenes were identified as (5αH,10βMe)‐6,12‐oxido‐elema‐1,3,6,11(12)‐tetraene, 6,12‐oxido‐germacra‐1(10),4,6,11(12)‐tetraene, (1βH,5βH)‐6,12‐oxido‐guaia‐6,10(14),11(12)‐trien‐4α‐ol and germacra‐1(10),4,7(11)‐trien‐6,12‐γ‐lactone. Finally, sixty‐eight constituents were identified in both investigated essential oil samples. They accounted for 96.1 and 97.3%, respectively, of the whole chemical composition of S1 and S2. Leaf essential oil from Idewevrei is very rich in sesquiterpenes. Indeed, its majority compounds were germacrene B (20.8 and 24.8%), (5αH,10βMe)‐6,12‐oxido‐elema‐1,3,6,11(12)‐tetraene (10.3 and 0.3%, new compound), germacrene D (7.5 and 17.8%), (Z)‐β‐ocimene (7.8 and 9.7%),γ‐elemene (6.9 and 7.5%) and (E)‐β‐caryophyllene (6.8 and 3.5%). The contents of thermolabile components were assessed by combination of GC(FID) and 13C‐NMR.

Sporulation on blood serum increases the virulence of Mucor circinelloides

Mucor circinelloides is an opportunistic human pathogen that is used to study mucormycosis, a rare but lethal infection in susceptible immunosuppressed patients. However, the virulence characteristics of this pathogen have not been fully elucidated. In this study, sporangiospores (spores) produced on YPG medium supplemented with native blood serum increased the virulence of M. circinelloides compared with spores produced on YPG supplemented with denatured blood serum or on YPG alone. The spores produced from YPG supplemented with native blood serum increased nematode death and led to significant increases in interleukin (IL)-6, IL-1β, macrophage inhibitory protein-2, and tumour necrosis factor α mRNA levels in liver and lung tissues from infected diabetic mice compared with those in tissues from animals infected with spores produced in the presence of YPG supplemented with denatured blood serum or of YPG alone. Moreover, spores produced from cultures supplemented with native blood serum showed increased germination rates and longer hyphae compared with other spores. The spores produced in YPG supplemented with native blood serum also enhanced resistance to stress factors and H2O2 and increased thermotolerance compared with spores produced under other conditions. In addition, spores produced in presence of blood serum increased the ability of the pathogen to survive in the presence of macrophages. Taken together, our results showed that these factors were important features for fungal virulence in humans and suggested that thermolabile components in the blood serum may induce M. circinelloides virulence.

Современные тенденции в переработке молочной сыворотки

The integrated use of secondary raw milk is one of the most effective ways to optimize the processing of raw materials in the production of dairy products. The unique composition and properties of curd whey makes it a valuable industrial raw material that can be processed into a variety of foods and feed products. Nowadays, whey protein concentrates (WPC) are extremely popular with consumers. One of the promising areas of industrial processing of acid whey is the extraction of proteins by means of separate freezing (cryoconcentration). This process takes place at low temperatures (from 0 to minus 15°C), which makes it possible to preserve the composition and properties of the raw material, prevents denaturation of whey protein fractions, and preserves its valuable thermolabile components. The authors conducted laboratory tests of curd whey and WPC produced by several dairy companies. The research allowed the authors to determine the composition, sensory, physico-chemical, and microbiological properties of the samples. The research objective was to evaluate the sensory properties of the initial cheese whey and WPC obtained by cryoconcentration, to establish their chemical composition, as well as physico-chemical and microbiological parameters. The research also featured the effect of the whey acidity on the WPC output and the development of technological schemes of WPC production by separate freezing. All the samples of curd whey proved to meet the current standards and can be used for WPC production. The sample of laboratory-obtained WPC sample had 20.19% of dry substances and 12.80% of protein, which corresponds to the standard albumin with its 20.0% of dry substances. The titratable acidity of WPC did not exceed the permissible level of 95°T. The experimental results proved that the cryoconcentration technology produced concentrate that met the requirements of regulatory and technical documentation. The obtained data revealed an increase in titratable acidity from 47°T to 50°T during the storage of curd whey for 7 days. The increase in acidity increased the yield of WPC after 7 days of serum storage by 57.6%. The new WPC production scheme consisted of several stages: (1) the whey was obtained; (2) casein dust and dairy fat were excluded;
 (3) pasteurization; (4) two-stage cryoconcentration; (5) thermal coagulation of whey concentrate; (6) separation of WPC. The technology of cryoconcentrationcurd whey suggests designing industrial installations in-line type to obtain CSB.

DEVELOPMENT OF RECIPTURES OF CANNED SMOTHIES MADE FROM ZUCCHINI AND FRUITS

Rational nutrition for a whole year is possible with a well-established system of storage and processing of plant raw materials. Products with vegetable and fruit raw materials due to their availability and nutritional value are in demand among the population. There is a constant interest in new products with increased biological value. The preservation of ascorbic acid, the main source of which is vegetables and fruits, is also affected by the technology of production. Despite the damaging effect of the heat treatment temperature of canned products on thermolabile components, the sterilization regimes should be relaxed. To this end, it has been proposed to produce beverages from vegetables and fruits for scientifically-based recipes, which allows them to be processed at a temperature of 100 °C, as well as juices with pulp and sugar. Smoothie, made on the basis of zucchini with the addition of gooseberries and blackcurrant puree contain respectively 13.3 and 41.8 mg/100 g of ascorbic acid, have an optimal for good perception of the sugar-acid index 21,4-21,5 compared with juices from soft pulp and sugar from gooseberry and black currant, which produces industry. The latter is explained by the fact that instead of sugar syrup, natural juice from zucchini was used in the recipe.

Composition and Chemical Variability of Enantia polycarpa Engl. & Diels Leaf Essential Oil from Côte d'Ivoire.

The composition of Enantia polycarpa Engl. & Diels leaf essential oil has been investigated for the first time using a combination of chromatographic and spectroscopic techniques. The compositions of 52 leaf essential oil samples have been subjected to statistical analysis, hierarchical cluster analysis (HCA) and principal component analysis (PCA). Four groups were differentiated, of which the compositions were dominated by β-elemene and germacrene B (Group III, 22/52 samples); germacrene D (Group I, 16/52 samples); β-cubebene (Group IV, 8/52 samples) and by germacrene B and germacrene D (Group II, 6/52 samples). A special attention was brought to the quantification of the thermolabile components, germacrene A, germacrene B and germacrene C, as well as that of their rearranged compounds, β-elemene, γ-elemene and δ-elemene. 13 C-NMR data of β-cubebene have been provided.

Supercritical Fluid Extraction of Bioactive Compounds from Plant Materials.

There has been growing interest in the application of supercritical solvents over the last several years, many of the applications industrial in nature. The purpose of plant material extraction is to obtain large amounts of extract rich in the desired active compounds in a time-sensitive and cost-effective manner. The productivity and profitability of a supercritical fluid extraction (SFE) process largely depends on the selection of process parameters, which are elaborated upon in this paper. Carbon dioxide (CO2) is the most desirable solvent for the supercritical extraction of natural products. Its near-ambient critical temperature makes it suitable for the extraction of thermolabile components without degradation. A new approach has been adopted for SFE in which the solubility of nonpolar supercritical CO2 can be enhanced by the addition of small amounts of cosolvent.

Rheological investigation of pectin-based emulsion gels for pharmaceutical and cosmetic uses

Emulsion gels are structured emulsions suitable for different uses for their specific behaviour, which is strongly dependent on the characteristics of the gelled dispersing phase. Therefore, it is important to adopt the specific gelling agent to tune the final emulsion rheological behaviour properly. Pectin is extremely interesting among potential hydrophilic gelling agents owing to its specific characteristics. In the present work, four different low-methoxyl pectins were adopted to prepare gels to be used as the dispersing phase in cosmetic or pharmaceutical emulsion gels. The rheological characterisation of pectin gels, prepared at room temperature to avoid the damage to potential thermolabile components, was carried out with small amplitude oscillations. The obtained gels were used, together with a common non-ionic surfactant (Tween 60), to prepare olive oil emulsion gels suitable to design new cosmetic products. A simple empirical model, proposed to relate the emulsion complex modulus to the oil fraction and properties of the dispersing phase, has shown itself to be a potentially useful tool to design formulations with desired properties.

Controlling the physical form of mannitol in freeze-dried systems

A potential drawback with the use of mannitol as a bulking agent is its existence as mannitol hemihydrate (MHH; C6H14O6·0.5H2O) in the lyophile. Once formed during freeze-drying, MHH dehydration may require secondary drying under aggressive conditions which can be detrimental to the stability of thermolabile components. If MHH is retained in the lyophile, the water released by MHH dehydration during storage has the potential to cause product instability. We systematically identified the conditions under which anhydrous mannitol and MHH crystallized in frozen systems with the goal of preventing MHH formation during freeze-drying. When mannitol solutions were cooled, the temperature of solute crystallization was the determinant of the physical form of mannitol. Based on low temperature X-ray diffractometry (using both laboratory and synchrotron sources), MHH formation was observed when solute crystallization occurred at temperatures⩽−20°C, while anhydrous mannitol crystallized at temperatures⩾−10°C. The transition temperature (anhydrate – MHH) appears to be ∼−15°C. The use of a freeze-dryer with controlled ice nucleation technology enabled anhydrous mannitol crystallization at ∼−5°C. Thus, ice crystallization followed by annealing at temperatures⩾−10°C can be an effective strategy to prevent MHH formation.

Application of the methods of thermal analysis for the assessment of organic matter in postpyrogenic soils

Experimental data on the effect of surface fires on the organic matter transformation in the gray-humus soils of pine forests were obtained in the southwestern part of the Baikal region. The application of methods of thermal analysis (such as differential scanning calorimetry and thermogravimetry) made it possible to obtain qualitative and quantitative information about the decomposition (oxidation) of the components of the soil organic matter upon their heating. It was found that the organic matter content in the soils subjected to fires of high intensity decreased by 1.9 times in comparison with the control. In the litter horizons of the undisturbed soils, thermolabile components (mostly, oligo- and polysaccharides) comprised 61% of the organic matter, and the portion of thermostable components (aromatic compounds) was 39%. A significant decrease in the content of thermolabile components and an increase in the content of thermostable components (up to 62%) were observed in the organic matter of the postpyrogenic forest litter as a result of the charcoal formation during the fire.

Molecular Analysis of Bacterial Community DNA in Sludge Undergoing Autothermal Thermophilic Aerobic Digestion (ATAD): Pitfalls and Improved Methodology to Enhance Diversity Recovery

Molecular analysis of the bacterial community structure associated with sludge processed by autothermal thermophilic aerobic digestion (ATAD), was performed using a number of extraction and amplification procedures which differed in yield, integrity, ability to amplify extracted templates and specificity in recovering species present. Interference to PCR and qPCR amplification was observed due to chelation, nuclease activity and the presence of thermolabile components derived from the ATAD sludge. Addition of selected adjuvant restored the ability to amplify community DNA, derived from the thermophilic sludge, via a number of primer sets of ecological importance and various DNA polymerases. Resolution of community profiles by molecular techniques was also influenced by the ATAD sludge extraction procedure as demonstrated by PCR-DGGE profiling and comparison of taxonomic affiliations of the most predominant members within 16S rRNA gene libraries constructed from ATAD DNA extracted by different methods. Several modifications have been shown to be necessary to optimize the molecular analysis of the ATAD thermal niche which may have general applicability to diversity recovery from similar environments.

STUDY ON INTERACTION AMONG EXTRUSION‐COOKING PROCESS VARIABLES AND ENZYME ACTIVITY: EVALUATION OF EXTRUDATE STRUCTURE

ABSTRACT A blend of wheat flour (moisture content 11.61%) and different amounts of two commercial enzymes like GRINDAMYL (GA) amylase 1000 (0–0.1 g/kg) and GA protease 41 (0–1.0 g/kg) were extruded through a co‐rotating twin‐screw extruder. The effects of barrel temperature (60–120C), dough moisture (20–36%), screw speed (100–400 rpm) and different amounts of enzymes on structure of extrudates (porosity and break strength) were studied using response surface methodology. Results showed that the highest value of porosity (62.47% ± 4.07) was obtained at the highest value of barrel temperature (120C) and at the largest amounts of GA protease 41 (1.0 g/kg) or GA amylase 1000 (0.1 g/kg). However, the simultaneous addition of large amounts of both enzymes caused a negative effect on expansion degree (porosity < 30%). Large amounts of moisture dough and GA amylase 1000 resulted in a high value of break strength (25.7 N/mm2) and in stiff‐textured extrudates.PRACTICAL APPLICATIONSThis research could provide some information about the effects of and the interactions between extrusion parameters and enzyme activities, which are commonly used to produce bakery products, in order to improve the texture of extrudates processed at low barrel temperatures, i.e., 60C, for example, extrudates with thermolabile components like vitamins or extrudates with high lipid fraction like breakfast cereals, pet food, etc.

Seminal plasma improves cryopreservation of Iberian red deer epididymal sperm

We tested the protective action of seminal plasma on epididymal spermatozoa from Iberian red deer, especially considering cryopreservation, as a means for germplasm banking improvement. We obtained seminal plasma by centrifuging electroejaculated semen, and part of it was thermically inactivated (denatured plasma; 55 °C 30 min). Epididymal samples (always at 5 °C) were obtained from genitalia harvested after regulated hunting, and pooled for each assay (five in total). We tested three seminal plasma treatments (mixing seminal plasma with samples 2:1): no plasma, untreated plasma and denatured plasma; and four incubation treatments: 32 °C 15 min, 5 °C 15 min, 5 °C 2 h and 5 °C 6 h. After each incubation, samples were diluted 1:1 with extender: Tes-Tris-Fructose, 10% egg yolk, 4% glycerol; equilibrated for 2 h at 5 °C, extended down to 10 8 spz./mL and frozen. Sperm quality was evaluated before 1:1 dilution, before freezing and after thawing the samples, assessing motility (CASA) and viability (percentage of viable and acrosome-intact spermatozoa; PI/PNA-FITC and fluorescent microscopy). Plasma treatment, both untreated and denatured, rendered higher viability before freezing and higher results for most parameters after thawing. The improvement was irrespective of incubation treatment, except for viability, which rendered slightly different results for untreated and denatured plasma. This may be due to the presence of thermolabile components. We still have to determine the underlying mechanisms involved in this protection. These results might help to improve the design of cryopreservation extenders for red deer epididymal sperm.

Occurrence and nature of thermolabile compounds in the Boom Clay kerogen (Oligocene, underground Mol Laboratory, Belgium)

The Boom Clay Formation has been selected as a model for studying the long term disposal of high activity nuclear waste in clay. During the resulting storage, the immature kerogen in the clay would be subjected to thermal stress and some of the products which could be generated might affect the efficiency of the geological barrier. The kerogen isolated from a representative clay sample, collected in the underground laboratory of the Nuclear Energy Research Centre at Mol (Belgium), was subjected to short heating at 300 °C to examine the thermolabile fraction released. The fraction contains a wide variety of components including hydrocarbons, ketones, alkanoic acids, phenols, furans and pyrroles. Information about the origin of these compounds was obtained through comparison with the bitumen and with the previously examined pyrolysis products generated from the kerogen at higher temperature (400 °C). The thermolabile fraction appears to correspond to “free” compounds trapped in the macromolecular structure of the kerogen and “labile” moieties linked by covalent bonds with a relatively low thermal stability. The study affords additional information on the sources and composition of the kerogen. Furthermore, the thermolabile components in the Boom Clay kerogen might affect the effectiveness of the clay barrier when subjected to thermal stress, especially through the release of oxygen-containing products, like carboxylic acids and phenols, that might complex released radioactive elements.