Małgorzata Serowik

In this study, a two-step chemoenzymatic route was developed for the synthesis of symmetrical acylglycerol–stigmasterol conjugates bearing a stigmasterol moiety at the sn-2 position and saturated acyl chains (decanoyl, C10, or stearoyl, C18) at the sn-1,3 positions. The use of Candida antarctica lipase B (CALB) under mild conditions (0–5 °C) ensured high regioselectivity, successfully preventing acyl migration and eliminating the need for complex protection/deprotection steps. The impact of the synthesized conjugates on DPPC (1,2-dipalmitoyl-sn-glycero-3-phosphocholine) model lipid membranes was evaluated using dynamic light scattering (DLS), differential scanning calorimetry (DSC), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), and fluorescence spectroscopy. Incorporation of the conjugates broadened the main phase transition of DPPC, reduced membrane fluidity in the liquid-crystalline phase, and limited interfacial hydration in a concentration- and chain-length-dependent manner. The short-chain derivative (C10) maintained smaller, homogeneous liposomes and disrupted lipid packing in the gel phase, whereas the longer-chain derivative (C18) promoted stronger hydrophobic interactions within the bilayer core. These findings highlight the potential of chemoenzymatically derived lipid–phytosterol conjugates for the precise tailoring of nanocarriers in functional food and nutraceutical delivery systems.

The rapid expansion of high-protein dairy-based powders (HPDPs), including milk protein concentrates and isolates (MPC/MPI), whey protein concentrates and isolates (WPC/WPI), and micellar casein concentrates and isolates (MCC/MCI), has intensified the need to understand instability phenomena that emerge during processing and storage. These products are governed by protein-rich amorphous matrices, in which molecular mobility, interfacial composition, and mineral interactions dictate both physical stability and functional performance. Importantly, these physical instabilities are directly coupled with functional deterioration, particularly in terms of impaired wetting, dispersion, and dissolution during rehydration. This review presents an integrated mechanistic framework linking these instability phenomena across processing, storage, and reconstitution, thereby consolidating concepts that remain fragmented across the current literature on high-protein dairy matrices. Key controlling factors include glass transition temperature (Tg), water activity-induced plasticization, protein–protein and protein–mineral interactions, and surface compositional heterogeneity established during spray drying. These factors govern the progression from surface stickiness through uncontrolled agglomeration to caking, forming a consolidation continuum. In contrast to lactose-driven matrices, caking and agglomeration in HPDPs arise primarily from protein-mediated restructuring and inter-particle bonding, with lactose crystallization acting only as a secondary mechanism in mixed-composition grades. The review further distinguishes engineered agglomeration from storage-induced consolidation and evaluates advances in molecular mobility characterization and Tg-based stability mapping. Significant gaps remain in linking localized surface evolution, mineral redistribution, and inter-particle bridge chemistry under realistic environmental conditions. The review concludes by proposing a mobility-centered “stability-by-design” framework that integrates composition, processing, particle architecture, and storage conditions to guide the development of future HPDPs with improved physical stability and functional recovery.

Caking represents a critical stability challenge for whey permeate powders (WPPs), frequently developing during storage and handling due to moisture-driven structural transformations within the powder bed. This study investigated the physical, morphological, and microstructural characteristics associated with caking in a limited set of industrial WPPs. Five commercial WPP samples differing in production date and storage conditions were characterized in terms of dry matter content, water activity (a_w), particle size distribution (PSD), bulk density, porosity, color, and X-ray micro-computed tomography (micro-CT). Dry matter contents were similar among samples (97.74–98.20% w.b.); however, significant differences were observed in a_w, bulk density, porosity, and PSD between the caked sample (WPP2) and the free-flowing powders. WPP2 exhibited the highest a_w (0.261), the lowest bulk density (676 kg/m³), the highest porosity (0.569), and a distinctly coarser PSD. In addition, WPP2 showed the highest yellowness index (44.45), suggesting altered light-scattering behavior associated with structural changes. Micro-CT analysis revealed the presence of enlarged particle clusters and extensive particle–particle solid bridging in WPP2, accompanied by a heterogeneous pore distribution and reduced void connectivity, indicating consolidation of the powder bed. The integrated analytical approach demonstrates the potential of combining conventional measurements with micro-CT to provide detailed insight into the relationships between moisture-related properties and internal powder structure.

The study focused on utilizing post-process osmotic solution enriched with inulin or maltodextrin, evaluating its potential for spray drying. Parameters such as yield, energy consumption, and the physical properties of the dried solutions and powders—including moisture content (Mc), water activity (Aw), color, true and bulk density, porosity, and glass transition temperature—were analyzed. The effects of carrier type, concentration, and inlet temperature (Tin) were systematically examined. Samples dried with maltodextrin demonstrated over 50% higher yield than those with inulin, with a highest yield of 32.13 ± 0.64% (with maltodextrin) and a lowest yield of 2.75 ± 0.48% (with inulin). Higher Tin improved drying efficiency by reducing Mc but also caused darker powders. Energy consumption increased with rising Tin, peaking at 2295 ± 51 kJ. The Spray Drying Energy Index (SDEI) was introduced to assess energy consumption relative to powder yield, with the most favorable SDEI values observed for processes with the highest total energy consumption. These same samples exhibited lower Mc and Aw values. The lowest bulk density was 0.455 ± 0.004 g·cm⁻³, while porosity was 58.3 ± 0.7%. The results highlight the potential of spray drying as a sustainable method for utilizing by-products from osmotic dehydration, aligning with the principles of sustainable food practices.

The study focused on utilizing post-process osmotic solution enriched with inulin or maltodextrin, evaluating its potential for spray drying. Parameters such as yield, energy consumption, and the physical properties of the dried solutions and powders—including moisture content (Mc), water activity (Aw), color, true and bulk density, porosity, and glass transition temperature—were analyzed. The effects of carrier type, concentration, and inlet temperature (Tin) were systematically examined. Samples dried with maltodextrin demonstrated over 50% higher yield than those with inulin, with the highest yield of 32.13±0.64% and the lowest yield of 2.75±0.48%. Higher Tin improved drying efficiency by reducing Mc but also caused darker powders. Energy consumption increased with rising Tin, peaking at 2295±51 kJ. The Spray Drying Energy Index (SDEI) was introduced to assess energy consumption relative to powder yield, with the most favorable SDEI values observed for processes with the highest total energy consumption. These same samples exhibited lower Mc and Aw values. The lowest bulk density was 0.455±0.004 g·cm-3, while porosity was 58.3±0.7%. The results highlight the potential of spray drying as a sustainable method for utilizing by-products from osmotic dehydration, aligning with the principles of sustainable food practices.

We have been advancing the concept of carbonized refuse-derived fuel (CRDF) by refuse-derived fuel (RDF) torrefaction as improved recycling to synergistically address the world’s energy demand. The RDF is a combustible fraction of municipal solid waste (MSW). Many municipalities recover RDF for co-firing with conventional fuels. Torrefaction can further enhance fuel properties and valorize RDF. Energy demand for torrefaction is one of the key unknowns needed for scaling up CRDF production. To address this need, a pioneering model for optimizing site-specific energy demand for torrefaction of mixed RDF materials was developed. First, thermogravimetric and differential scanning calorimetry analyses were used to establish thermal properties for eight common RDF materials. Then, the model using the %RDF mix, empirical thermal properties, and torrefaction temperature was developed. The model results for individual RDF components fitted well (R² ≥ 0.98) with experimental torrefaction data. Finally, the model was used to find an optimized RDF site-specific mixture with the lowest energy demand. The developed model could be a basis for estimating a net energy potential from the torrefaction of mixed RDF. Improved models could be useful to make plant-specific decisions to optimize RDF production based on the energy demand that depends on highly variable types of MSW and RDF streams.

The pioneering developed simplified mathematical model can be used to determine the energy consumption of the torrefaction process. Specifically, the energy balance model was developed for torrefaction of municipal solid waste (MSW; a combustible fraction of common municipal waste). Municipalities are adopting waste separation and need tools for energy recovery options. This type of model is needed for initial decision-making, evaluation of cost estimates, life cycle analysis (LCA), and for optimizing the torrefaction of MSW. The MSW inputs are inherently variable and are site-, location-, and country-dependent. Thus, in this model, MSW inputs consist of eight types of common municipal waste components: chicken meat, diapers, gauze, eggs packaging, paper receipts, cotton, genuine leather, and polypropylene. The model uses simple experimental input consisting of thermogravimetric (TGA) and differential scanning calorimetry (DSC) analyses for each type of individual MSW material. The model was created in a Microsoft Office Excel spreadsheet and is available for download and use for site-specific waste mixes and properties. The model allows estimating the energy demand of the process depending on the percentage composition of the MSW and the final torrefaction temperature. The model enables initial optimization of the torrefaction process regarding its energy demand by changing the proportion of MSW mix and the final temperature.