Search Results (137)

Previous research has primarily focused on the antioxidant effect of astaxanthin (AX) in various vegetable oils, with limited attention given to its behavior in lard. This study aimed to evaluate the degradation of AX during lard storage and to assess the physicochemical changes occurring in lard containing different AX concentrations over time. The variation in AX concentration was monitored using spectrophotometric analysis. To characterize the changes in lard, both thermal and chemical methods were employed: thermal analysis was used to determine the onset oxidation temperature (To) and activation energy (Ea), while chemical methods included peroxide value (PV) and thiobarbituric acid reactive substance (TBA) assays. Optimization of AX concentration and temporal evaluation of its antioxidant effect were performed using Response Surface Methodology (RSM). The results indicated a significant degradation of AX after 30 days of storage. An AX concentration of approximately 3 mg/g was identified as optimal, as it provided the highest thermal stability and the lowest levels of oxidation markers, offering a well-balanced compromise between technological performance and preservative effectiveness in lard during storage. Additionally, the color of the lard was found to be more strongly influenced by the presence of AX itself rather than by its specific concentration. Full article

The quality and freshness of fruits and vegetables are critical factors in consumer acceptance and are significantly affected during transport and storage. This study aimed to evaluate the quality of greenhouse-grown tomatoes stored for 24 days by combining non-destructive image analysis, spectrophotometric assays (including total phenolic content and antioxidant and antiradical activity assessments), and attenuated total reflectance–Fourier transform infrared (ATR-FTIR) spectroscopy. Additionally, water activity, moisture content, total soluble solids, texture, and color were evaluated. Most physicochemical changes occurred between days 14 and 17, without major impact on overall fruit quality. A progressive transition in peel hue from orange to dark orange, and increased surface irregularity of their textural image were noted. Moreover, the combined use of instrumental and image analyses results via multivariate analysis allowed the clear discrimination of tomatoes according to storage days. In this sense, tomato samples were effectively classified by ATR-FTIR spectral bands, linked to carotenoids, phenolics, and polysaccharides. Machine learning (ML) models, including Random Forest and Gradient Boosting, were trained on image-derived features and accurately predicted shelf life and quality traits, achieving R² values exceeding 0.9. The findings demonstrate the effectiveness of combining imaging, spectroscopy, and ML for non-invasive tomato quality monitoring and support the development of predictive tools to improve postharvest handling and reduce food waste. Full article

The colour evolution of malvidin-3-O-glucoside (Mv-3-O-glc) elicited by caffeic acid (CAF), (+)-catechin (CA), or syringic acid (SI) was spectrophotometrically monitored in model wine solution, modulating the malvidin-to-polyphenol molar ratio (1:1 to 1:20) and the pH (2.8–3.8). The spectral features provided the thermodynamic parameters Gibbs free energy (ΔG⁰) and equilibrium constant (K_eq), showing that the copigmentation extent is maximized at pH 3.6 and a higher molar ratio (1:20), and that copigments have different efficiency. In a long-term evolution (12 months), transient complexes evolved into different colour characteristics. Spectrophotometry and colorimetry (chroma C*, hue H*, and lightness L*) revealed the formation of stable pigments with peculiar orange-reddish colour when CAF was present; however, in the case of CA, an accentuated yellow tone was observed. SI showed minimum impact in the long-term evolution of Mv-3-O-glc. This study expands knowledge on oenological copigmentation, further exploring its potential implication in the colour of aged red wines. Full article

Microalbuminemia, characterized by a urinary albumin concentration between 20 and 200 mg/L, is a critical marker in assessing the risk of chronic kidney disease (CKD), diabetic nephropathy, and various other chronic conditions. Previously, we developed and validated the MyACR point-of-care (PoC) device, which facilitates the monitoring of CKD progression through real-time data transmission, thus enhancing patient management. This device utilizes a spectrophotometric dye-binding assay to measure albumin and creatinine concentrations in urine samples, providing an albumin-to-creatinine ratio (ACR) result. In the present study, we introduced a refined version of the PoC device, MyμAlbumin, designed to offer a simple, accurate, specific, sensitive, and rapid method for detecting microalbumin in urine as an early indicator of CKD and related diseases. The measurement is based on a specific immunoturbidimetric assay in a microcuvette, using a total solution volume of 125 µL (n = 5 for each validation test). The MyμAlbumin device demonstrated excellent performance, achieving high accuracy (%DMV ≤ 4.67) and precision (%CV < 5) and a strong correlation (R² > 0.995) with laboratory spectrophotometry (dye-binding assay) and reference hospital-based immunoturbidimetric assay. Its high sensitivity (LOQ = 5 mg/L) positions MyμAlbumin as a highly viable and cost-effective tool for clinical use. Additionally, the device supports real-time, seamless data transmission, making it ideal for integration into remote healthcare settings. Full article

The growing demand for sustainable phytosanitary products has renewed interest in botanical insecticides as viable pest control tools. Amid rising demand for sustainable crop protection, this study screens Cerrado plants traditionally used in medicine to pinpoint bioactive compounds that could replace synthetic pesticides. These products have complex chemical compositions, with compounds acting synergistically through multiple mechanisms, including oral (ingestion of allelochemicals) and topical (contact of allelochemicals on epidermis) toxicity. This study evaluated the oral and topical toxicity of aqueous leaf extracts from Anemopaegma arvense (AEAa), Coussarea hydrangeifolia (AECh), Tapirira guianensis (AETg), and Duguetia furfuracea (AEDf) on Plutella xylostella. In the oral toxicity test, first-instar larvae were fed treated diets until pupation, with biological parameters monitored until adulthood. The extracts caused an average of 45% larval mortality, reduced pupal duration, and lowered egg production. In the topical toxicity test, only the extract from T. guianensis showed significant effect (p = 0.0171), causing 30% mortality in third-instar larvae. The other extracts showed no significant topical toxicity, and AECh showed no lethal or sublethal effects at all. Phytochemical screening was assessed by quantitative spectrophotometric assays, and semi-quantitative classical colorimetric tests. Major compound classes identified were tannins, flavonoids, triterpenoids, coumarins, and alkaloids. These findings highlight the potential of the evaluated plant extracts for pest control, particularly via ingestion, while also underscoring the need for further studies to better understand their efficacy and mechanisms of action. Full article

Background: Alzheimer’s disease (AD) is a progressive neurodegenerative disorder characterized by cognitive decline, synaptic dysfunction, and neuronal loss. Identifying reliable biomarkers for early diagnosis and disease monitoring remains a critical need. Objective: This study aimed to investigate the serum levels of NPAS-4 (Neuronal PAS Domain Protein 4) and NPTX-2 (Neuronal Pentraxin 2) in patients with Alzheimer’s disease, exploring their potential roles in disease pathophysiology and their relationship with lipid parameters. Methods: This was a cross-sectional study that included 63 patients diagnosed with Alzheimer’s disease and 56 age- and sex-matched healthy controls. Venous blood samples were collected from all participants. NPAS-4 and NPTX-2 levels were measured using the ELISA method, while lipid parameters were analyzed via spectrophotometric techniques. Cognitive assessment was performed using the Standardized Mini-Mental Test (SMMT). Comparative analyses between groups, correlation studies, logistic regression, and ROC analyses were conducted. Results: Serum NPAS-4 and NPTX-2 levels were significantly lower in Alzheimer’s patients compared to healthy controls (p < 0.001 and p = 0.001, respectively). Additionally, total cholesterol and LDL levels were lower in the patient group. Logistic regression analysis identified NPAS-4 as an independent risk predictor for Alzheimer’s disease (OR = 0.313, p < 0.001). ROC analyses demonstrated that both biomarkers had significant diagnostic discrimination power. However, no significant correlation was found between NPAS-4 and NPTX-2 levels and SMMT scores or lipid parameters. Conclusions: The decreased levels of NPAS-4 and NPTX-2 in Alzheimer’s patients may reflect biochemical manifestations of impaired synaptic plasticity. These findings suggest that NPAS-4 and NPTX-2 may serve as potential early biomarkers in the diagnosis and monitoring of Alzheimer’s disease. Full article

This study showcases an attached-biomass system based on twin-layer technology for cultivating Galdieria phlegrea using municipal wastewater, equipped with a smart sensor system for the remote monitoring of operational parameters. From an industrial scale-up perspective, the system offers high scalability, with low impact and operating costs. Mathematical approximation modelling identified the optimal growth conditions across five experiments. The theoretical yield was estimated to reach 1 kg_DW/m² of biomass within two months. Integrated use of isotopic mass spectrometry and spectrophotometric methods allowed us to study the metabolic strategies implemented by the algal community during the best growth condition at different resolutions, showing an increase in the nitrogen concentration over time and a favourable affinity of the organism for nitrogen species that are commonly present in the urban effluent. SEM studies showed a clean algal biofilm (free of foreign organisms), which could guarantee usage in the high economic potential market of biorefineries. Full article

Catalase serves as a crucial component of the antioxidant defense system by catalyzing the decomposition of hydrogen peroxide into water and molecular oxygen. This study investigated the effects of 1 MeV accelerated electron irradiation on catalase activity in model solutions at doses of 100 Gy and 1000 Gy. Enzyme activity was assessed using two complementary methods: spectrophotometric analysis and the oxygen bubble method. The experimental results demonstrated dose-dependent inhibition of catalase activity, indicating that substantial radiation-induced structural modifications may occur in the enzyme molecule as a result of irradiation. To understand the relationship between the irradiation dose and the catalase inhibition, calibration curves plotting the dependencies of hydrogen peroxide decomposition rate and the delayed appearance of oxygen bubbles after adding hydrogen peroxide to catalase saline solution on the catalase concentration showed a 1.5-fold reduction in catalase activity at 100 Gy and a 40-fold decrease at 1000 Gy. Based on these findings, we propose a novel biodosimetry approach utilizing the oxygen bubble formation delay time as an express assessment tool for detecting high radiation doses absorbed by biological objects, for example, food products. The results obtained in the study have important implications for evaluating radiation effects on biological systems, in particular catalase-containing food products, offering potential applications in radiation safety monitoring and food quality control. Full article

Ammonium concentrations in marine environments are typically found at the nanomolar level, and due to the transformation tendencies of ammonium species, there is a growing demand for a simple, convenient, and highly sensitive automated method for seawater ammonium quantification. Such a method should be suitable for in situ applications without the need for additional enrichment or extraction steps. To meet this need, we developed a highly sensitive automated flow system that integrates a portable LED-induced fluorescence detector, incorporating the novel AccuOpt 2000 photodetector and lab-in-syringe technology, enabling direct fluorescence measurement of trace ammonium in seawater. Key system parameters were optimized, and the seawater matrix effects were assessed. The system achieved a detection limit of 0.90 nmol/L, with a linear range up to 400 nmol/L and relative standard deviations of 0.94% (100 nmol/L, n = 21). The sensitivity was nearly ten-fold higher than those of conventional approaches. Seawater matrix effects, including carryover, were negligible. The system’s measurements correlated well with the indophenol blue spectrophotometric method. These results underscore the system’s strong potential for in situ/on-site monitoring of trace ammonium levels in marine environments. Full article

Based on the potential of DPSCs as the most promising candidates for bone tissue engineering, we comprehensively investigated the time-dependent cellular and molecular changes that occur during their osteodifferentiation. To analyze this area in-depth, we used both cellular and molecular approaches. Morphological changes were monitored using bright-field microscopy, while the production of mineral deposits was quantified spectrophotometrically. The expression of a key mesenchymal stem cell marker, CD90, was assessed via flow cytometry. Finally, protein-level changes in whole cells were examined by fluorescence microscopy. Our results show successful long-term osteodifferentiation of the patient’s DPSCs within 25 days. In differentiated cells, mineralized extracellular matrix production gradually increased; in contrast, the expression of the specific stem cell marker CD90 significantly decreased. We observed dynamic changes in intracellular and extracellular proteins when collagen1 A1 and osteopontin appeared as earlier markers of osteogenesis, while apolipoprotein A2, bone morphogenetic protein 9, dentin sialophosphoprotein, and matrix metalloproteinase 8 were produced mainly in the late stages of this process. A decrease in actin microfilament expression indicated a reduction in cell proliferation, which could be used as another marker of osteogenic initiation. Our results suggest a coordinated process in vitro in which cells synthesize the necessary proteins and matrix components to regulate the growth of hydroxyapatite crystals and form the bone matrix. Full article

Self-cleaning cementitious materials, particularly with TiO₂-based photocatalytic coatings, offer significant benefits by reducing surface deterioration and maintenance requirements, even in harsh urban environments. Despite the growing interest in self-cleaning cementitious materials, an international standard test method to calculate their efficiency has not yet been established for this specific type of substrate. The objective of this study was to evaluate and compare three different techniques for assessing the photocatalytic efficiency (PE) of cementitious materials coated with TiO₂: (i) spectrophotometric colorimetry (SPC); (ii) digital image processing-based colorimetry (DIP); and (iii) UV-Vis spectrophotometry (UV-Vis). Rhodamine B (RhB) was used as a model pollutant, and the photocatalytic efficiency was monitored under UV-Vis light. The results showed that each method has distinct advantages and specific challenges. SPC proved to be a practical and efficient approach, similarly to DIP, which was also accessible, providing reliable and accurate measurements. UV-Vis stood out for its precision but required careful application on cement-based substrates due to their unique porosity and adsorption characteristics. These results underscore the complementary potential of these techniques and highlight the importance of developing standardized protocols that integrate their strengths to facilitate the wider adoption of self-cleaning materials. Full article

Nitrates (V) in drinking water are harmful to human health and are a probable carcinogen. Nitrates (V) in drinking water are responsible for the formation of methaemoglobin, which causes hypoxia, cyanosis, collapse and even death. Newborn babies and infants up to six months of age are most at risk. For this reason, a European Union directive was introduced in 1991 to protect waters from pollution caused by nitrogenous fertilisers of agricultural origin, restricting their use. The aim of the study was to analyse the content of nitrogen compounds (ammoniacal nitrogen, nitrates (III and V)) in water samples from selected rural waterworks in Tłokinia Wielka. Analyses were performed using spectrophotometric methods. The results showed that excessive levels were present in the tap water from public water supplies, which are regularly monitored by the State Sanitary Inspectorate and water supply companies. Full article

This research was conducted to determine the connections between dissolved oxygen (DO), chemical oxygen demand (COD), permanganate index (CODMn), five-day biochemical oxygen demand (BOD₅), and ammonia nitrogen (NH₃-H) across five reservoirs of Yunmeng County, China, from January to November 2022. Each month, water samples were collected and subjected to analysis using standard methods. The samples were collected and analyzed using standard methods: dissolved oxygen was determined using the electrochemical probe method, COD was measured via the rapid digestion spectrophotometric method, CODMn was detected using the potassium permanganate oxidation method, BOD₅ was determined using the dilution and inoculation method, and NH₃-N was measured by using the Nessler reagent spectrophotometry method. The results confirmed strong positive correlations between COD and CODMn, with different intensities from reservoir to reservoir. More specific and demanding COD parameters were used to estimate the level of oxygen consumption; hence, a more variable correlation strength was observed between BOD₅ and the other two parameters. Thus, BOD₅ was found to be the main indicator of biodegradable organic matter and bacterial oxygen consumption. However, the results were negative, showing a decreasing trend. This means that the oxygen content was lower in the majority of reservoirs, which is attributed to the decomposition of ammonia nitrogen and the presence of organic matter. These findings significantly contribute to the development of appropriate programs for efficient water quality monitoring and the development of reservoir-specific management strategies. This study suggests that there is a need for continuous monitoring of these parameters, together with the extension of the program to additional reservoirs and water quality indicators, along with the use of advanced modeling techniques to clarify the underlying factors that connect water quality parameters in these complex reservoir ecosystems. Full article

Spectrophotometry is widely used in biological sciences. In bacteriology, spectrophotometric monitoring of cell numbers during cultivation provides a rapid assessment of growth. Unfortunately, familiarity with this technique has led scientists to become complacent in its usage. Here, we review some guiding principles of spectrophotometry and practical considerations that may influence the outcome of experiments. This perspective is intended to assist both new and seasoned scientists in presenting robust and reproducible growth data based on spectrophotometric readings. Full article

Background/Objectives: Ultraviolet radiation (UVR) induces oxidative stress in the skin by generating reactive oxygen species (ROS), which can lead to inflammatory conditions including erythema (a sign of sunburn). This clinical study aims to develop an instrumental evaluation method to determine the minimal erythema dose (MED) for UVR. Methods: Fourteen human subjects aged 27 to 57 years (48.93 ± 8.54) participated in this study. Six subsites were designated on the test skin site of each subject and irradiated with UVR at different doses. The examiner visually assessed erythema, determining the ‘visual MED’. Additionally, the a* value (a chrominance parameter presenting greenness to redness) was measured using a spectrophotometer as an indicator of erythema. The a* values of the UVR-irradiated subsites were compared to the non-irradiated control value, and the differences were referred to as Δa*. The Δa* value of the subsites irradiated with UVR at the ‘visual MED’ was referred to as the Δa*_VMED for each subject. The mean of the Δa*_VMED values of all subjects was chosen as a criterion value for the ‘instrumental MED’. The ‘instrumental MED’ was defined as the lowest dose of UVR that causes an Δa* value equivalent to the criterion value. The ‘visual MED’ and ‘instrumental MED’ values of all subjects were subjected to correlation analysis. Results: The mean of the Δa*_VMED values of all subjects was 1.88 ± 0.8. The means of the ‘visual MED’ and ‘instrumental MED’ values (in J m⁻² unit) of all subjects were 300.14 ± 84.16 and 303.29 ± 77.99, respectively. In Pearson correlation analysis, the ‘instrumental MED’ and ‘visual MED’ values had a very strong positive correlation with each other (r = 0.864, p = 0.000). Conclusions: This study suggests that the instrumental evaluation method of MED based on the spectrophotometric measurement of the a* values can complement or replace the visual evaluation method and that this method will be useful in monitoring skin tolerance to oxidative stress affected by prooxidant factors and defensive factors. Full article