This study presents a comprehensive evaluation of starch-based gel formulations enriched with proteins and hydrocolloids for extrusion-based 3D food printing (3DFP). Food inks were prepared using corn or potato starch, protein concentrates (fava, whey, rice, pea and soya), and hydrocolloids (κ-carrageenan, arabic gum, xanthan gum, and carboxy methylcellulose). Their rheological, mechanical, and textural properties were systematically analyzed to assess printability. Among all formulations, those containing κ-carrageenan consistently demonstrated superior viscoelastic behavior (G′ > 4000 Pa), optimal tan δ values (0.096–0.169), and yield stress conducive to stable extrusion. These inks also achieved high structural fidelity (93–96% accuracy) and favourable textural attributes such as increased hardness and chewiness. Computational Fluid Dynamics (CFD) simulations further validated the inks’ performances by linking pressure and velocity profiles with rheological parameters. FTIR analysis revealed that gel strengthening was primarily driven by non-covalent interactions, such as hydrogen bonding and electrostatic effects. The integration of empirical measurements and simulation provided a robust framework for evaluating and optimizing printable food gels. These findings contribute to the advancement of personalized and functional 3D-printed foods through data-driven formulation design.

Mechanical processes impact (conventional mixing, high-speed shear mixing, and ultrasonication) on the physicochemical, mechanical, and thermal properties of starch gels combined with plant protein concentrates (pea, fava-bean, pumpkin, rice) and κ-carrageenan were evaluated. Conventional and high-speed shear mixing reduced values of strain (γl), yield stress (τf) storage modulus (G’), complex viscosity (η*), and increased tanδ magnitudes, being more prominent in fava-bean (G’_{PSF C}= 11416 ± 48, G’_{PSF HS} = 5421 ± 37), pea (G’_{PSP C}= 6188 ± 39 G’ _{PSF HS} = 2984 ± 30), and pumpkin protein-starch gels (G’_{PSPU C}= 14840 ± 107, G’_{PSF HS} = 7066 ± 42), (p < 0.05).While no significant rheological alterations were observed for rice-protein gels (G’_{PSR C}= 10802 ± 98, G’_{PSR HS} = 10044 ± 76). Ultrasonication process had a smaller effect on viscoelastic properties compared to other shear methods (e.g. G’_{PSP C}= 6188 ± 39, G’_{PSP US} = 5775 ± 72). Firmness increased with high shear processing, ∼ 3 times for fava bean and ∼ 2 times for pea and pumpkin protein-starch gels. In contrast, shearing of rice protein-starch complex resulted in softer gels, particularly with ultrasound treatment. The thermomechanical properties displayed shear-induced changes in onset, peak, and conclusion temperatures of gelatinization, and decreased enthalpy values, with varying sensitivity to each protein concentrate. Research findings have important implications for optimizing food product development by customizing processing techniques and hydrocolloids interactions to achieve desired texture and functionality in various food applications such as extrusion-based three-dimensional food-printing.

This study explored the potential of chitosan (CH)/bacterial cellulose (BC) complexes (0.5% w/v) as novel emulsifiers to stabilize oil-in-water (o/w) Pickering emulsions (20% v/v sunflower oil), with a focus on their gel-like behavior. Emulsions were prepared using CH combined with BNC derived via H₂SO₄ (BNC1) or H₂SO₄-HCl (BNC2) hydrolysis. Increasing BNC content improved stability by reducing phase separation and enhancing viscosity, while CH contributed interfacial activity and electrostatic stabilization. CH/BNC1_25:75 emulsions showed the highest stability, maintaining an emulsion stability index (ESI) of up to 100% after 3 days, with minimal change in droplet size (R_h ~8.5–8.8 μm) and a positive ζ-potential (15.1–29.8 mV), as confirmed by dynamic/electrophoretic light scattering. pH adjustment to 4 and 10 had little effect on their ESI, while ionic strength studies showed that 0.1 M NaCl caused only a slight increase in droplet size combined with the highest ζ-potential (−35.2 mV). Higher salt concentrations led to coalescence and disruption of their gel-like structure. Rheological analysis of CH/BNC1_25:75 emulsions revealed shear-thinning behavior and dominant elastic properties (G′ > G″), indicating a soft gel network. Incorporating sunflower-seed protein isolates into CH/BNC1 (25:75) emulsions led to coacervate formation (three-layer system), characterized by a decrease in droplet size and an increase in ζ-potential (up to 32.8 mV) over 7 days. These findings highlight CH/BNC complexes as sustainable stabilizers for food-grade Pickering emulsions, supporting the development of biopolymer-based emulsifiers aligned with bioeconomy principles.

Olive oil production generates large amounts of agricultural and agro-industrial residues, with olive leaves representing one of the most abundant by-products. This study investigated the valorization of olive leaves from two Greek cultivars, Koroneiki and Megaritiki, collected from the Aeghion, Heraklion, and Megara regions, by means of an optimized green extraction process for the effective recovery of phenolic compounds. Response surface methodology (RSM) was applied to optimize solvent composition and extraction time using ethanol/water mixtures (0/100, 30/70, 50/50, and 70/30, v/v) and extraction times ranging from 15 to 90 min. Total phenolic content (TPC), antioxidant activity (DPPH and FRAP), and color parameters were determined spectrophotometrically, while individual phenolic compounds were analyzed by HPLC-DAD. Both solvent composition and extraction time significantly affected phenolic recovery and antioxidant activity. The optimal extraction conditions were 37.5/62.5 (v/v) ethanol/water and 52.5 min. Extracts from Megara showed the highest TPC (32 ± 1 g GAE kg⁻¹ LL), antioxidant capacity (2556 ± 162 mmol Trolox kg⁻¹ LL), and phenolic compound levels. Significant differences were observed between the two cultivars, whereas Koroneiki samples from Heraklion and Aeghion exhibited similar phenolic profiles, indicating that cultivars had a greater influence than geographical origin.