Search Results (159)

Agriculture is one of the most important sectors of the global economy, but it increasingly faces sustainability challenges in meeting rising food demands. The intensive use of mineral fertilizers not only improves yields, but also causes negative environmental impacts such as increasing greenhouse gas emissions, water eutrophication, and soil degradation. To develop more sustainable solutions, the focus is on organic fertilizers, which are produced using waste and biostimulants such as amino acids. The aim of this study was to develop and characterize liquid nitrogen–calcium–magnesium fertilizers produced by decomposing dolomite with nitric acid followed by further processing and to enrich them with a powdered amino acid concentrate Naturamin-WSP and liquid extracts from digestate, a by-product of biogas production. Nutrient-rich extracts were obtained using water and potassium hydroxide solutions, with the latter proving more effective by yielding a higher organic carbon content (4495 ± 0.52 mg/L) and humic substances, which can improve soil structure. The produced fertilizers demonstrated favourable physical properties, including appropriate viscosity and density, as well as low crystallization temperatures (eutectic points from –3 to –34 °C), which are essential for storage and application in cold climates. These properties were achieved by adjusting the content of nitrogenous compounds and bioactive extracts. The results of the study show that liquid fertilizers enriched with organic matter can be an effective and more environmentally friendly alternative to mineral fertilizers, contributing to the development of the circular economy and sustainable agriculture. Full article

To advance the development of protein-rich plant-based foods, a novel binder system for vegan sausage alternatives without the requirement of heat application was investigated. This enables long-term ripening of plant-based analogs similar to traditional fermented meat or dairy products, allowing for refined flavor and texture development. This was achieved by using a poorly water-soluble calcium source (calcium carbonate) to introduce calcium ions into a low-ester pectin—gluten matrix susceptible to crosslinking via divalent ions. The gelling reaction of pectin–gluten dispersions with Ca²⁺ ions was time-delayed due to the gradual production of lactic acid during fermentation. Firm, sliceable matrices were formed, in which particulate substances such as texturized proteins and solid vegetable fat could be integrated, hence forming an unheated raw-fermented plant-based salami-type sausage model matrix which remained safe for consumption over 21 days of ripening. Gluten as well as pectin had a significant influence on the functional properties of the matrices, especially water holding capacity (increasing with higher pectin or gluten content), hardness (increasing with higher pectin or gluten content), tensile strength (increasing with higher pectin or gluten content) and cohesiveness (decreasing with higher pectin or gluten content). A combination of three simultaneously occurring effects was observed, modulating the properties of the matrices, namely, (a) an increase in gel strength due to increased pectin concentration forming more brittle gels, (b) an increase in gel strength with increasing gluten content forming more elastic gels and (c) interactions of low-ester pectin with the gluten network, with pectin addition causing increased aggregation of gluten, leading to strengthened networks. Full article

The intensifying global demand for sustainable and nutrient-dense food sources necessitates the exploration of underutilized local resources. Arthrospira platensis var. toliarensis, a cyanobacterium endemic to Madagascar, was evaluated for its nutritional, functional, and environmental potential under small-scale, low-input outdoor cultivation. The study assessed growth kinetics, physicochemical parameters, and composition during two contrasting seasons. Biomass increased 7.5-fold in 10 days, reaching a productivity of 7.8 ± 0.58 g/m²/day and a protein yield of 4.68 ± 0.35 g/m²/day. The hot-season harvest showed significantly higher protein content (65.1% vs. 44.6%), enriched in essential amino acids. On a dry matter basis, mineral profiling revealed high levels of sodium (2140 ± 35.4 mg/100 g), potassium (1530 ± 21.8 mg/100 g), calcium (968 ± 15.1 mg/100 g), phosphorus (815 ± 13.2 mg/100 g), magnesium (389.28 ± 6.4 mg/100 g), and iron (235 ± 9.1 mg/100 g), underscoring its value as a micronutrient-rich supplement. The hydroethanolic extract had the highest polyphenol content (4.67 g GAE/100 g of dry extract), while the hexanic extract exhibited the strongest antioxidant capacity (IC₅₀ = 101.03 ± 1.37 µg/mL), indicating fat-soluble antioxidants. Aflatoxin levels (B1, B2, G1, and G2) remained below EU safety thresholds. Compared to soy and beef, this strain showed superior protein productivity and water-use efficiency. These findings confirm A. platensis var. toliarensis as a promising, ecologically sound alternative for improving food and nutrition security, and its local production can offer substantial benefits to smallholder livelihoods. Full article

The sustainable valorization of electrolytic manganese residue (EMR) and fly ash (FA) presents critical environmental challenges. This study systematically investigates the performance optimization of EMR-FA ceramic composites through the coordinated regulation of raw material ratios, sintering temperatures, and additive effects. While the composite with 85 g FA exhibits the highest mechanical strength, lowest porosity, and minimal water absorption, the formulation consisting of 45 wt% EMR, 40 wt% FA, and 15 wt% kaolin is identified as a balanced composition that achieves an effective compromise between mechanical performance and solid waste utilization efficiency. Sintering temperature studies revealed temperature-dependent property enhancement, with controlled sintering at 1150 °C preventing the over-firing phenomena observed at 1200 °C while promoting phase evolution. XRD-SEM analyses confirmed accelerated anorthite formation and the morphological transformations of FA spherical particles under thermal activation. Additive engineering demonstrated that 8 wt% CaO addition enhanced structural densification through hydrogrossular crystallization, whereas Na₂SiO₃ induced sodium-rich calcium silicate phases that suppressed anorthite development. Contrastingly, ZrO₂ facilitated zircon nucleation, while TiO₂ enabled progressive performance enhancement through amorphous phase modification. This work establishes fundamental phase–structure–property relationships and provides actionable engineering parameters for sustainable ceramic production from industrial solid wastes. Full article

The clean-label movement has markedly increased consumer demand for meat products free from synthetic additives, such as sodium nitrite, ascorbate, and phosphate. This review summarizes strategies to replace these additives with natural alternatives while preserving the functional and quality properties of traditionally cured meats. Nitrite replacement commonly employs nitrate-rich vegetables, alongside nitrate-reducing starter cultures or pre-converted nitrite powders for adequate nitric oxide production and meat pigment stabilization. Ascorbate substitutes include vitamin C-rich materials and polyphenol-based antioxidants from green tea and rosemary, supporting nitrite reduction and contributing to meat pigment and oxidative stability. To compensate for phosphate functions, natural substitutes such as hydrocolloids, dietary fibers, protein isolates, and calcium powders from eggshells or oyster shells have shown partial success in restoring water-holding capacity, pH buffering, and textural integrity. In addition, non-thermal processing technologies, such as high-pressure processing, ultrasound, and cold plasma are explored as complementary strategies to enhance the efficacy of natural ingredients and support industrial scalability. However, challenges persist regarding ingredient variability, dose-dependent effects, and consistency in functional performance. Future research should focus on synergistic ingredient combinations, formulation standardization, and scalable application in industrial production to ensure the production of high-quality clean-label meat products. Full article

Acid–base balance is critical to human health and can be significantly influenced by dietary choices. The Western diet, characterized by high meat and cheese consumption, induces excess acidity, highlighting the need for strategies to mitigate this. Recent studies have focused on bicarbonate-rich mineral water as a viable solution. In this context, the present narrative review synthesizes the findings from recent scientific studies on bicarbonate-rich mineral water, specifically those with bicarbonate levels over 1300 mg/L and medium or low PRAL values. This water has been shown to exert beneficial effects on both urinary and blood parameters. The key effects include an increase in the urine pH and a profound reduction in net acid excretion as a sign for a reduced acid load. Additionally, bicarbonate mineral water has been shown to decrease the excretion of nephrolithiasis-related constituents, including calcium and oxalates, as well as inhibitory substances such as magnesium and citrates. In blood, bicarbonate-rich water has been demonstrated to stabilize pH and increase bicarbonate levels, thereby enhancing systemic buffering capacity. Clinically, these changes have been associated with a lowered risk of calcium oxalate stone formation and improved kidney health. Furthermore, bicarbonate-rich water has been shown to support bone health by reducing bone resorption markers. Consequently, the integration of bicarbonate-rich mineral water into the diet has the potential to enhance urinary and blood parameters, mitigate the risk of kidney stones, and strengthen skeletal integrity, thereby serving as a promising strategy for health promotion and disease prevention. While promising, these findings underscore the need for further research to establish long-term recommendations. Future interventional studies should be designed with rigorous randomization, larger sample sizes, cross-over methodologies, and comprehensive dietary assessments to address the methodological limitations of previous research. Full article

Macrophytes are important components of aquatic ecosystems performing essential ecological functions. Their species composition and density reflect the ecological status of water bodies. The optimal ratio of morphological types of macrophytes is an important condition for preventing eutrophication. The aim of the study is to analyse the species composition, distribution, and density of macrophytes in the Vyzhyvka River (Ukraine) in a seasonal aspect (2023–2024) under constant physical and chemical characteristics of water. To assess the seasonal dynamics of water quality, changes in indicators in three representative areas were analysed. The MIR method of environmental indexation of watercourses was used to assess the ecological state of the river. The water quality in the Vyzhyvka River at all test sites corresponds to the second class of the “good” category with the trophic status of “mesotrophic”. This is confirmed by the identified species diversity, which includes 64 species of higher aquatic and riparian plants. Among the various morphological types of macrophytes, submerged rooted forms account for only 10.56% of the total species composition. To ensure a functional balance between submerged and other forms of macrophytes, a scientifically based approach is proposed, which involves the use of mineral raw materials of local origin, in particular, mining and quarrying wastes rich in silicon, calcium and other mineral components. The results obtained are of practical value for water management, environmental protection, and ecological reclamation and can be used to develop effective measures to restore river ecosystems. Full article

Stratlingite is known as one of the hydration products of aluminum-rich cements. Its microstructure and, consequently, mechanical properties, depend on the Al/Si ratio and hydration conditions. The layered structure of stratlingite is characterized as defected, with vacancies in the aluminosilicate layer. This study uses density functional theory calculations on different stratlingite models to show how chemical composition, water content, and structural defects affect its mechanical properties. The developed models represent structures with full occupancy, with little or no content of structural water, and with vacancies in the aluminosilicate layer. It was shown that the full occupancy models have the highest toughness and are strongly anisotropic. The calculated bulk modulus (B_H) of the models with full occupancy was about 40 GPa, being in the typical range for calcium aluminosilicate minerals. The water loss led to an increase in B_H by approximately 40% compared to the models with full occupancy. In contrast, the models with vacancies exhibited a decrease in B_H of about 30%. In models with the high silicon content (Al/Si ratio of 1/4), B_H, Young’s (E_H), and shear (G_H) moduli decreased in a range 15%–30% compared to the models with an Al/Si ratio of 2/3 of Al/Si. Finally, according to Pugh’s ratio (B_H/G_H), which serves as a criterion for brittle–ductile transition (1.8), the models with full occupancy exhibit a brittle behavior, whereas the defected structures are closer to ductile. This could explain the elastic behavior of stratlingite binder in concretes. Generally, the calculations showed that all investigated parameters (chemical composition, water content, and structural defects) have a significant impact on the mechanical properties of stratlingite minerals. Full article

By-products from the fruit and vegetable processing industry represent a substantial source of bioactive compounds, which can be extracted and utilized in the development of functional foods or nutraceuticals, thereby contributing to sustainable nutrition and waste valorization. Pumpkin peels are particularly abundant in bioactive components and contain significant fiber, protein, and minerals such as calcium and magnesium. This study determined the chemical composition, the content of water- and fat-soluble vitamins, and the antioxidant activity of peels from five pumpkin species: Cucurbita pepo ‘Kamo Kamo’, C. maxima ‘Bambino’, C. moschata ‘Butternut’, C. argyrosperma ‘Chinese Alphabet’, and C. ficifolia ‘Chilacayote Squash’. The highest moisture content was observed in the peels of C. ficifolia (89.2 mg 100 g⁻¹ WW). In contrast, the highest amounts of protein (14.82 mg 100 g⁻¹ DW), fat (1.59 mg 100 g⁻¹ DW), and ash (7.46 mg 100 g⁻¹ DW) were recorded in C. maxima peels. The peels of C. moschata contained the highest levels of total sugars (9.17 mg 100 g⁻¹ DW), reducing sugars (8.48 mg 100 g⁻¹ DW), and fiber (19.04 mg 100 g⁻¹ DW). The peels of all analyzed pumpkin species were rich in amino acids and water- and fat-soluble vitamins. The highest levels of polyphenols and flavonoids and the most potent antioxidant properties (DPPH and FRAP) were found in the extract from C. argyrosperma peels. The findings of this study highlight the potential of pumpkin peels as a valuable source of bioactive compounds. Full article

A cast is an object that results from a fossilization process that is considerably rare in nature. For a cast to be produced, secondary diagenetic processes during and after fossilization are normally involved. Natural casts are formed when minerals are deposited within the fossil mold. Here we describe an exceptional example of the natural cast by gypsum of an ammonite presumably preserved as a limestone-made “half” mold that had previously been transported as an extraclast, deposited and dissolved within Upper Pliocene quartz sandstones of the ancestral Tejo river. Portable X-ray fluorescence was used to analyze and compare the geochemical composition of the ammonite fossil with that of the nodules found within the same bed, reflecting different diagenetic timings. The composition of the ammonite cast reflects the in situ dissolution of limestone and the precipitation of calcium sulfate. High δ³⁴S‰ and Sr values obtained from the ammonite show that the cast was produced by percolating acidic waters in the vadose zone, under marine influence, during the Late Pliocene or already in the Pleistocene. The waters being rich in sulfur resulted more likely from a marine water-influenced water table. Alternatively, it may have resulted from the weathering concentration of sulfur from the Marco Furado ferricretes overlying Santa Marta sandstone. This is, so far, the only testimony of the enormous temporal discontinuity that occurred during the taphonomic history of an ammonite, with a final preservation in the form of a cast made of gypsum, the most didactic example of this type of fossilization ever found in Portugal. Full article

Glauconite, a diagenetic sedimentary phyllosilicate mineral, holds significant importance in soil science, as it is commonly used in soil characterization (as in greensands) and can be identified in the field by its color and morphology. It is a potential fertilizer, rich in essential macronutrients like potassium, phosphorus, calcium, and numerous micronutrients such as manganese, zinc, copper, cobalt, and nickel. In this meticulously conducted study, we extracted five individual elements (potassium, calcium, magnesium, sodium, and zinc) from washed glauconite samples separated into five different size fractions using a suite of acids. The acids employed were nitric acid, hydrochloric acid, acetic acid, and phosphoric acid, each prepared at the same molarity of 0.1 M. Water was used as the control solubilizing medium. The extractant behavior of the acids was assessed by measuring concentrations of each element by the ICP-OES device. The results demonstrate that nitric acid consistently exhibits the highest efficacy in releasing elements, followed by hydrochloric acid and phosphoric acid, while acetic acid results in the lowest release of these nutrients. These findings support the use of acidification treatment of glauconite, enhancing elemental release and potentially reducing the amount of glauconite needed as an alternative fertilizer, thus adding economic value. Full article

Mushrooms are a valuable food in the human diet due to their superior nutritional properties. However, mushrooms’ short shelf life presents a challenge for their commercial application. Mushrooms’ air drying kinetics were determined, and the impact of prior osmotic dehydration was quantitatively evaluated. Additionally, the sustainable utilization of Rosa damascena distillation wastewater, rich in phenolics, was explored. Samples were impregnated with hypertonic solutions including rose wastewater, glycerol, salt and calcium chloride, and air-dehydrated at 40, 55, and 70 °C. Texture and color changes were determined during drying. Seven acknowledged mathematical models were successfully applied to describe the drying kinetics, with the effect of process temperature being incorporated into the drying constant. The simplest first-order model is deemed adequate for describing moisture reduction and quality degradation. Pretreatment significantly reduced the drying time to reach a final moisture content of 10% w.b, especially at 70 °C, where the reduction obtained was more than 40% (5 h for untreated vs. 2.5 h for pretreated samples). At the end of drying, pretreated samples reached lower values of water activity and maintained their color better (25–50% improvement). This study aims to provide a basis for producing a novel, mushroom-based, nutritionally fortified dry snack, following results confirmed by a sensory examination. Full article

Considering the urgent need for sustainable construction materials, this study investigates the mechanical and microstructural responses of novel hybrid geopolymer concrete blends incorporating Fly Ash (FA), Ground Granulated Blast Furnace Slag (GGBS), Cement (C) and Precipitated Silica (PS) as partial replacements for traditional cementitious materials. The motive lies in reducing CO₂ emissions associated with Ordinary Portland Cement (OPC). The main aim of the study was to optimise the proportions of industrial wastes for enhanced performance and sustainability. The geopolymer mixes were activated using a 10 M sodium hydroxide (NaOH)—Sodium Silicate (Na₂SiO₃) solution and cast into cubes (100 mm), cylinders (100 mm × 200 mm) and prism specimens for compressive, split tensile and flexural strength testing, respectively. Six combinations of mixes were studied: FA/C (50:50), GGBS/C (50:50), FA/C/PS (50:40:10), FA/GGBS/PS (50:40:10), GGBS/C (50:50) and GGBS/FA/PS (50:40:10). The results indicated that the blend with 50% FA, 40% GGBS and 10% PS exhibited higher strength. Mixes with GGBS and PS presented a l0 lower slump due to rapid setting and higher water demand, while GGBS-FA-cement mixes indicated better workability. GGBS/C exhibited a 24.6% rise in compressive strength for 7 days, whereas FA/C presented a 31.3% rise at 90 days. GGBS/FA mix indicated a 35.5% strength drop from 28 days to 90 days. SEM and EDS analyses showed that FA-rich mixes had porous microstructures, while GGBS-based mixes formed denser matrices with increased calcium content. Full article

Xanthan is a highly relevant commercial microbial biopolymer. Its production occurs in two steps: the bacterium is cultivated in a nitrogen-rich medium for cell multiplication, and the obtained biomass is used as an inoculum for the polymer production phase. Different media compositions for cell growth were investigated, seeking to reduce or replace the peptone used in the standard medium. Peptone (P), yeast extract (YE), and rice parboiling water (RPW) concentration combinations were tested in cultivating Xanthomonas arboricola pv. pruni 101. A CRD 2³ design, performed in a shaker, was used to assess the effects of independent variables on xanthan pruni microbial growth, N consumption, yield, viscosity, pseudoplasticity, and xanthan mineral content. After 24 h an increase in N was observed, without any significant impact on cell growth. Xanthan yield increased as a result of the alternative treatments, with P and YE influencing positively. However, T1, with the lowest levels of P, YE, and RPW increased viscosity and pseudoplasticity of xanthan pruni. RPW increased phosphorus, silicon, calcium, and magnesium, and P and YE increased potassium. These results indicate that partial replacement of P by RPW and YE is an economically viable and sustainable approach for the xanthan pruni production. Full article

With the rapid advancement of urbanization, the reuse of waste concrete has become more and more important. Recycled aggregate inevitably develops microcracks during the crushing process of waste concrete, resulting in undesirable characteristics such as low density and strong water absorption. This study employed an external calcium source combined with wet carbonation to optimize the performance of recycled fine aggregate (RFA). A series of microscopic analytical techniques, including scanning electron microscopy coupled with energy-dispersive spectroscopy (SEM-EDS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TG), and the Brunauer–Emmett–Teller (BET) method, were used to elucidate the underlying mechanisms. The results indicate that calcium-rich leachate can be obtained by soaking alkali residue in 0.3 mol/L acetic acid at a solid-to-liquid ratio of 1:6. When this leachate was further used to soak the aggregate at a solid-to-liquid ratio of 1:2, followed by carbonation in a carbonation chamber, the carbonation effect reached its optimum. Under these conditions, the saturated water absorption of the recycled fine aggregate decreased to 16%, the carbon sequestration efficiency increased by 66.8%, and pores smaller than 50 nm accounted for 62.9% of the total pore volume. Furthermore, a Bacillus strain capable of producing carbonic anhydrase was introduced to enhance the carbonation reaction. The results demonstrated that when Bacillus was added to acetic acid-modified recycled fine aggregate, the saturated water absorption further decreased to 14.6%, while the carbon sequestration efficiency significantly increased to 109.04%. Additionally, pores smaller than 50 nm constitute 79.2% of the total pore volume. These findings suggest that utilizing calcium-containing industrial waste as a calcium source for recycled fine aggregate, followed by carbonation modification, is highly effective. This approach not only improves the performance of recycled aggregates but also promotes the reutilization of industrial waste, contributing to sustainable construction practices. Full article