Search Results (519)

This study compares the roles of eye-tracking and verbal reports (think-alouds and retrospective verbal reports, RVRs) in L2 reading process research through three qualitative studies. Findings indicate that eye-tracking provided precise, quantitative data on visual attention and reading patterns (e.g., fixation duration, gaze plots) and choice-making during gap-filling. Based on our mapping, it was mostly effective in identifying 13 out of 47 reading processing strategies, primarily those involving skimming or scanning that had distinctive eye-movement signatures. Verbal reports, while less exact in measurement, offered direct access to cognitive processes (e.g., strategy use, reasoning) and uncovered content-specific thoughts inaccessible to eye-tracking. Both methods exhibited reactivity: eye-tracking could cause physical discomfort or altered reading behavior, whereas think-alouds could disrupt task flow or enhance reflection. This study reveals the respective strengths and limitations of eye-tracking and verbal reports in L2 reading research. It facilitates a more informed selection and application of these methodological approaches in alignment with specific research objectives, whether employed in isolation or in an integrated manner. Full article

The prevalence of chronic diseases, including obesity and related endocrine disorders, has risen significantly in recent decades. As a result, there has been growing interest in fermented foods with probiotic properties, such as kefir, which have potential health benefits. This study aimed to evaluate the hepatoprotective and antioxidant effects of kefir milk (KM) in a high-fat diet (HFD)-induced obesity rat model, complemented by in silico molecular docking studies with antioxidant enzymes. Twenty-four adult rats were divided into four groups: control (1 mL/100 g bw semi-skimmed cow milk), KM (1 mL/100 g bw kefir milk), HFD (1 mL/100 g bw semi-skimmed cow milk + high-fat diet), and KM/HFD (1 mL/100 g bw kefir milk + high-fat diet). After 60 days of treatment, biochemical assays and histological examinations were performed to assess the effects on lipid profiles and organ health. Kefir milk demonstrated significant antioxidant activity, with increased total phenolic content and enhanced DPPH, ABTS, and FRAP radical scavenging activities compared to commercial milk. Furthermore, KM administration protected against liver metabolic disruptions (ALT, AST, and LDH) induced by the high-fat diet and reduced lipid peroxidation in liver and testis tissues. KM supplementation also increased the activity of key antioxidant enzymes, including superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx). Additionally, KM improved the fatty acid composition and decreased the de novo lipogenesis (DNL) index, as well as enzyme activities (SCD and Elovl6) associated with the high-fat diet. Histological analysis of liver, pancreas, and heart tissues revealed that kefir milk attenuated structural damage caused by the high-fat diet, suggesting its protective role in oxidative stress regulation and organ function. These findings underscore the potential of kefir milk as a functional food for preventing metabolic disturbances and liver damage associated with obesity. Full article

The limited heat stability of skim milk powder (SMP) constrains its application in high-temperature processes. While dry heating can improve its thermal resistance, it often accelerates the advanced Maillard reaction, compromising protein quality. This study applied low relative humidity conditions (<10% RH) during dry heating to modulate the Maillard reaction, aiming to enhance the heat resistance of SMP and derive recombined filled evaporated milk emulsions with fewer undesirable changes in colour and solubility. SMP was subjected to dry heating at 80, 100, and 120 °C for durations ranging from 2 to 20 min (at 120 °C) and up to 16 h (at 80 °C). The progression of the Maillard reaction and associated protein modifications were evaluated. The results indicate that the advanced Maillard reaction was retarded, evidenced by minimal colour development and well-preserved protein solubility (90–97%, n = 3), determined using the Lowry assay on the supernatants. The hydroxymethylfurfural and protein carbonyl contents increased only moderately with temperature and time. Moreover, the sulfhydryl group content remained largely stable, consistent with limited disulfide-mediated aggregation. Heat treatment of SMP at 120 °C for 10 min greatly improved its heat stability, as reflected by a 25-fold reduction in the volume-weighted average diameter (D_4,3; 95% CI = 3 to 47) and a 108-fold reduction in the consistency coefficient (K; 95% CI = 12 to 200) of the SMP-derived sterilised recombined filled evaporated milk (RFEM) compared to the control. These findings demonstrate that dry heating under low RH helps to improve the functional properties of SMP without inducing the detrimental effects associated with advanced Maillard products. Full article

Natural whey starter (NWS) cultures are microbial consortia characterized by high microbial diversity in terms of genus and species, as well as strains, accounting for the variety of different characteristics and quality of the artisanal fermented food. By means of a combined approach, using plate counts, bacterial isolation, molecular identification, and genotyping, we analyzed 41 colonies isolated from NWS of cow milk used in the production of caciocavallo, a typical pasta filata Italian cheese. Results revealed that 27 of them were lactic acid bacteria (LAB), including Lactococcus lactis as the dominant species, followed by Streptococcus thermophilus, Enterococcus faecium, Limosilactobacillus fermentum, Lactobacillus helveticus, and Lacticaseibacillus rhamnosus. The remaining isolates were taxonomically identified as non-LAB, probably due to environmental contamination. These results were mostly confirmed by metagenomic analysis, with the exception of only three species. Finally, small-scale fermentation experiments were performed in both standard media and skimmed milk to further characterize the newly isolated LAB strains. Overall, our results show that, except for four of the Lactococcus isolates and one Streptococcus, which show multi-drug resistance, the isolated strains under study exhibit levels of acidifying, metabolic properties, and safety parameters, suggesting their potential as starter cultures in cheese production. Full article

Background: scleroglucan, an extracellular polysaccharide with gel-forming, thickening, and stabilizing properties, was used as a structure-forming agent in low-fat yogurt formulations. The aim of this study was to evaluate its influence on the fermentation process and the physicochemical, rheological, textural, microstructural, and sensory properties of the yogurts. Methods: control samples were formulated with the addition of skim milk powder (SMP), whereas experimental yogurts contained scleroglucan at concentrations of 0.25%, 0.5%, and 1.0% (w/w). The fermentation kinetics, acidity, color, syneresis, rheological behavior, texture profile, microstructure, and volatile compounds were analyzed during storage. Results: the results showed that scleroglucan slowed acidification and increased the apparent viscosity, yield stress, and firmness of yogurts, while completely eliminating syneresis. Scleroglucan also modified the volatile profile by decreasing acetaldehyde and increasing 2,3-pentanedione levels during storage. The survival of Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus was not affected. Conclusions: the yogurt containing 1.0% scleroglucan was rated highest in overall acceptability. These findings demonstrate that scleroglucan can serve as a natural, clean-label stabilizer and an alternative to skim milk powder in low-fat set-style yogurts. Full article

The study proposed a strategy using soybean protein hydrolysate (SPH) as the sole nitrogen source for promoting the proliferation and freeze-drying survival of Bifidobacterium breve and Bifidobacterium longum strains. High proportions of SPH replacing traditional nitrogen sources in MRSL significantly enhanced bacterial viable cell counts and OD₆₀₀ values. The small peptides (<3 kDa) and hydrophilic amino acid residues in SPH are considered to be the key factors for promoting bacterial growth. The exclusive use of SPH (100%-SPH) as the nitrogen source induced a morphological change in B. breve 1206 with the Y-shape transformation into smaller rod-shaped cells, while B. longum 070103 and 050101 became shorter rods. Cells with these morphological changes could more effectively maintain cell membrane integrity in an acidic condition and during the freeze-drying process. Consequently, MSPH improved cell viability and freeze-drying survival for B. breve 1206 in PBS and 10% skim milk compared to MRSL. It also significantly increased viable cell counts and the ability to survive freeze-drying for functional B. longum strains 070103 and 050101 in 10% skim milk, with survival rates increasing by 16.2% and 43.1%, respectively. These results showed the applicability of SPH in the industrial-scale cultivation of functional Bifidobacterium strains. It also provides new insights into soybean-derived nitrogen sources that can affect amino acid composition and bacterial morphology to enhance probiotic stability. This study supported the application of soybean peptides as the sole nitrogen source for producing high-viability probiotics and the potential prebiotic with health benefits. Full article

This study investigated the effects of different microencapsulation wall materials on the physicochemical, textural, thermal, and microstructural properties of probiotic ice cream during frozen storage. Lactobacillus acidophilus ATCC 4356 was encapsulated using lyophilization with whole milk powder, skim milk powder, whey powder, or sorbitol, and added to the ice cream mix at 1% (w/w). Five formulations were produced (control and four encapsulated variants) and analyzed over 90–150 days of storage at −18 °C. The highest firmness (41.96 g) and consistency (58.65 g·s) values were observed in the skim milk powder group, whereas sorbitol decreased viscosity and increased overrun. Melting resistance improved during storage, particularly in skim milk powder samples, where the complete melting time increased to 87.35 min. DSC results showed significantly higher enthalpy in whey powder samples, while sorbitol reduced ice crystal growth. Cryo-SEM images confirmed smoother, denser microstructures in formulations with milk powders and sorbitol. Encapsulation markedly enhanced probiotic survival: while the control decreased from 5.04 to 2.18 log CFU/g, encapsulated samples maintained counts above the therapeutic threshold (≥6 log CFU/g) up to 150 days, with the highest viability in whole and skim milk powder. Overall, milk-based encapsulation systems provided both cryoprotection and quality enhancement, demonstrating that microencapsulation is an effective strategy to produce stable probiotic ice creams with improved structural and technological attributes. Full article

The classical assumption of self-similarity in flow velocities and turbulence statistics has been successfully validated for fully developed flows in open channels, pipes, and boundary layers. However, its application in developing boundary-layer flows in channels with steep slopes and large roughness elements has not yet been thoroughly scrutinized. This study investigates whether turbulence statistics exhibit self-similar behavior when properly scaled in steep-stepped spillways. Specifically, it explores the influence of roughness height ($k_s$)—representing the cavity size of a steep-stepped spillway—on turbulence statistics in the non-aerated skimming flow region. Numerical simulations, extensively validated against experimental data, were conducted for a stepped spillway with a fixed slope angle of 51.34°, using five roughness heights ($k_s$ = 6.25, 3.12, 1.56, 0.78 and 0.39 cm), corresponding to step height-to-length ratios of 10:8, 5:4, 2.5:2, 1.25:1 and 0.625:0.5, respectively. The results show that the dimensionless profiles of turbulent kinetic energy (TKE) at the step edges collapse onto a single curve when rescaled by a factor of ${\left(\delta /k_s\right)}^n$ with $n~0.4$. Likewise, the dissipation rate of TKE follows a similar collapse with $n~0.3$. For the turbulent eddy viscosity, an exponent of $n~0.5$ was adopted based on dimensional analysis, although the values for the smoothest configuration deviate from the curve. Full article

This study investigated the effect of a concentrated kombucha inoculum and transglutaminase (TG) on the rheological and textural properties of fermented milk products and compared their average production costs to commercial yoghurt. Semi-skimmed milk was used, to which microbial TG was added at a level of 0.02% w/w. The kombucha inoculum, prepared from black tea, was concentrated to 55.6% total solids. Four samples were produced: two with TG and two without. The TG-containing samples showed significantly higher textural properties, including firmness and consistency, than the non-TG samples. They also exhibited the largest hysteresis loop area and the highest yield stress, indicating a stronger gel structure. The Herschel–Bulkley model successfully described the flow behaviour of all samples and confirmed their shear-thinning, non-Newtonian nature. Principal Component Analysis (PCA) showed that both TG addition and inoculum concentration significantly influenced the product properties. TG improved the rheological and textural properties and increased the stability during storage. However, the production costs for TG-treated samples were higher than those for non-TG-treated samples and commercial yoghurt. Nevertheless, the higher costs could be justified by the perceived additional nutritional benefits for consumers. Overall, the results show that the combination of concentrated kombucha inoculum with transglutaminase can improve the structural and rheological quality of fermented dairy products, which is potentially of commercial importance. Full article

The stability of spore-forming soil bacteria is crucial for their effective use in agricultural biopreparations. This study evaluated the long-term survivability of selected strains (Paenibacillus amylolyticus, Priestia megaterium, Bacillus velezensis, Bacillus subtilis, and Bacillus licheniformis) with potential applications in biopreparations for crop residue decomposition. The effects of different storage and preservation conditions on vegetative cells and bacterial spores were studied over 12 months. Bacteria were stored at different temperatures (15 °C, 21 °C, 30 °C), pH levels (5, 9, and post-cultivation liquid pH), and osmotic pressures (2%, 5%, and 10% of carbamide, calcium chloride, and multicomponent fertilizer). Additionally, freeze-drying, spray-drying and freezing were performed using cryoprotectants (skimmed milk, trehalose, and glycerol). The results showed that bacterial stability depended on both the strain and storage conditions. Vegetative cells of P. amylolyticus and B. velezensis were most sensitive to temperatures of 30 °C, whereas the spores of most strains demonstrated high temperature resistance. The tested strains exhibited better survivability at pH 5 than pH 9. The addition of calcium chloride, carbamide, or multicomponent fertilizer proved beneficial for maintaining viability, especially increasing spore numbers. Trehalose and skimmed milk were the most effective cryoprotectants overall, though efficacy varied by strain and cell form. These findings provide insight into the optimal conditions for preserving the bacterial viability of spore-producing bacteria in bioformulations, which is crucial for maintaining their effectiveness in agricultural applications. Full article

This study was conducted in two phases: first, to assess the impact of microbial fermentation on enhancing the nutritional quality of fish by-products, and second, to evaluate the effects of replacing fishmeal with these fermented by-products in the diet of Nile tilapia (Oreochromis niloticus) on growth performance, blood parameters, antioxidant indices, immunity, digestive enzyme activity, and carcass composition. In the initial phase, proteolytic activity of five bacterial strains including Bacillus subtilis (ATCC: 6051), B. licheniformis (IBRCM: 10204), Lactiplantibacillus plantarum (PTCCs: 1058 and 1745), and Lactobacillus casei (PTCC: 1608) was evaluated using growth assays in skimmed milk culture media and analyzed using Image-J software. B. licheniformis exhibited the highest proteolytic activity and was selected for fermentation. Resulting hydrolyzed proteins were characterized by peptides with molecular weights below 11 kDa. In the second phase, fishmeal was replaced with fermented by-products at five levels (0 (control), 25, 50, 75, and 100%). Two hundred ten Nile tilapia with an average weight of 2.83 ± 0.05 g were stocked in fifteen 200 L plastic tanks at three replicates, with 14 fish per tank, and fed daily at a rate of 7% of their body weight for 63 days. With increasing levels of fishmeal replacement (25% to 75%), significant improvements (p < 0.05) were observed in final weight gain, body weight gain, specific growth rate, protein production value, and protein efficiency ratio. Additionally, blood plasma concentrations of hormones T₃ and T₄, immunoglobulin level, the activities of complement (ACH₅₀), and antioxidant enzymes (catalase and superoxide dismutase) increased significantly in fish fed the diets with fermented by-products compared to those of the control diet (p < 0.05). The optimal replacement levels for specific growth rate and feed conversion ratio were identified as 86.28% and 83.91%, respectively. Full article

This study investigated the efficacy of different cryoprotectants (maltodextrin, skim milk, trehalose, sucrose, fructose, and dextrose) in protecting probiotic cultures isolated from the microbiota of arapaima (Arapaima gigas) (Enterococcus faecium CRBP46 and Enterococcus gallinarum CRBP19) during lyophilization, storage (−25 °C, 4 °C, and 25 °C for 120 days), and exposure to simulated gastrointestinal fluids (SGF). Cell surface hydrophobicity and the ultrastructural aspects of the coating matrices were also evaluated. Skim milk, trehalose, and dextrose (only for E. gallinarum) protected Enterococcus spp. against the negative effects of lyophilization, resulting in minimal viability loss (≤0.03 log CFU/g) and ≥99.50% survival. All cryoprotectants promoted stability (≥8.87 log CFU/g) for both bacteria when stored at refrigeration and freezing temperatures for 120 days. However, only skim milk maintained high viability (≥6.83 log CFU/g) for Enterococcus spp. during 120 days of storage at room temperature. Additionally, Enterococcus spp. lyophilized with skim milk demonstrated stability in SGF, with high cell viability (≥8.97 log CFU/g) and survival over 97%. Skim milk also significantly increased the cell adhesion capacity of Enterococcus spp., making them more hydrophobic. Scanning electron microscopy showed that Enterococcus cells were incorporated into the skim milk matrix and that its lower porosity directly contributed to the preservation of cell viability. Therefore, we conclude that skim milk is the most effective cryoprotectant under the tested conditions for E. faecium and E. gallinarum, as it ensured stability and high viability for both bacteria throughout all post-lyophilization challenges, maintaining bacterial concentrations above those suggested for probiotic formulations. Our findings provide unprecedented insights into the development of long-term stable, dry autochthonous probiotics, aiming to strengthen a more sustainable aquaculture for the arapaima, the Amazon’s giant fish. Full article

Background: With the advancement of the next-generation sequencing technology, it is becoming more cost-effective to obtain plastomes from genome skimming data at shallow sequencing depth. Artemisia is a species-rich genus, comprising species of great medicinal or economic value. However, plastomes of Artemisia have not been thoroughly and comparatively analyzed, and the phylogenetic relationships within the genus are still not well resolved. Methods: In this study, 19 Artemisia plastomes were obtained from genome skimming data. Together with the plastomes retrieved from the public database, comparative analyses of their structure were also conducted. We further used sequences of plastomes and nuclear internal transcribed spacer sequences to conduct phylogenetic reconstruction. Results: The Artemisia plastomes are conserved in terms of structure, GC content, gene number, and order. Some regions, i.e., accD, ccsA, ndhE, ycf1, ccsA-ndhD, trnG^GCC-trnfM^CAU, were found to be variable and could be chosen as candidates for the DNA barcode. Phylogenetic analyses also confirmed that the four subgenera of Artemisia are not monophyletic. The incongruence between plastid and nuclear phylogenies indicated that hybridization events have occurred during the evolution of the genus. Conclusions: Reconstructed phylogenies using plastome sequences and nuclear internal transcribed spacers improved our understanding of the phylogenetic backbone of Artemisia. In the future, more taxa of Artemisia should be sequenced and analyzed to clarify the evolutionary history. Full article

Doce de leite (DL) is a product originating in South America, particularly in countries such as Brazil, Argentina, and Uruguay. The product is widely used for direct consumption and industrial applications and can be added with thickening agents to modify its rheological properties. This study aimed to produce DL with the addition of three different components (skimmed milk powder—SMP, whey protein concentrate—WPC, and microparticulated whey protein—MWP) in two different concentrations (2.1 and 4.2%). The composition of the products aligned with Mercosur regulations, except for the fat content, where the result was slightly lower. The HMF (5-hydroxymethylfurfural) concentration in the samples was also determined, showing no statistically significant differences between products. The products with SMP showed a higher browning index and color saturation compared to WPC and MWP formulations. The addition of MWP increased the hardness (from 10.2 to 467.8 g), gumminess (from 8.2 to 362.1 g), and viscosity (from 6.7 to 18.3 Pa.s) of the DL compared to the control product (SMP). These findings suggest that adding MWP can modulate the rheological and textural characteristics of such products without significantly altering their proximate composition, offering an alternative to using thickeners in this type of product. Full article

(1) Background: The impact of different drying methods on the functional properties and microstructure of milk powders was analyzed in this study. (2) Methods: Whole milk, skim milk, and buttermilk powders were obtained by freeze drying, spray drying, and roller drying. (3) Results: The examined powders differed in chemical composition, and these differences were attributed mainly to their fat content. The functional properties of the studied powders were determined mainly by the drying method and were less influenced by their composition. Loose and tapped bulk density was highest in roller-dried powders and lowest in freeze-dried powders. The flowability of milk powders was determined by calculating the Carr index and the Hausner ratio, and the results were used to classify the analyzed powders into the following groups: poorly flowing and cohesive (spray-dried samples), passable (roller-dried samples), and fair (freeze-dried samples). The volume of insoluble particles was highest in roller-dried powders and much lower in spray-dried powders, whereas freeze-dried powders were 99.8–99.9% soluble in water. Whole milk powder was characterized by low wettability (>180 s) regardless of the drying method. Powder morphology was influenced mainly by the drying method. (4) Conclusions: The fractal analysis demonstrated that spray-dried powders had the smallest fractal dimensions, which implies that their surface was least complex (most uniform). Regardless of the drying method, fractal dimensions were highest in whole milk powder, which could suggest that fat affects the microstructure of powders. The color parameters of milk powders were determined mainly by the drying method and were less influenced by the type of raw material used in powder production. Full article