Search Results (731)

This study examines the nature of enzymatic degradation of polyethylene terephthalate (PET) films mediated by a novel recombinant LCC^ICCG PETase enzyme preparation based on P. verruculosum fungus. The investigation was conducted using amorphous PET samples and PET samples with varying degrees of crystallinity as substrates for PETase-catalyzed hydrolysis under different temperature and pH conditions. Mechanical testing revealed that enzymatic treatment reduced the yield stress by 20–25%, tensile strength by approximately twofold, and elongation at break by 5–10 times, while the deformation mechanism remained unchanged. Enzymatic degradation under acidic conditions was ineffective, whereas increasing the pH to 9–10 markedly accelerated PET degradation and the associated deterioration of mechanical properties. Thermal analysis (TGA, DSC) and microscopy (optical and scanning electron microscopy) demonstrated that degradation was localized at the polymer surface, leading to the formation of cavities, cracks, and submicron-sized pores rather than bulk material disintegration. An inverse correlation was observed between PET crystallinity and susceptibility to enzymatic degradation: samples with crystallinity below 13% could be almost completely degraded, whereas samples with crystallinity above 30% exhibited little or no measurable weight loss over the same period. Low-crystallinity PET underwent rapid degradation accompanied by a transient increase in crystallinity, while highly crystalline PET primarily accumulated surface defects that nevertheless caused a substantial loss of mechanical strength. Consequently, the experimental data obtained in this study provide useful information for understanding PET degradation and for future studies on enzymatic PET recycling. The systematization of feedstock characteristics and the elucidated patterns of enzymatic degradation will enable optimization of pretreatment, enzymatic hydrolysis, and monomer recovery process parameters, thereby facilitating the eventual production of secondary raw materials. Full article

The valorization of salmon farming by-products is an essential strategy within the circular economy. This study optimized the enzymatic hydrolysis of salmon frame proteins using Alcalase 2.5L and response surface methodology (RSM). The effects of temperature (50–60 °C), substrate concentration (50–100% w/w), and protease dose (1–13 mAU/g salmon frames) were evaluated on two key responses: degree of hydrolysis (DH) and nitrogen recovery (NR). The 20 experimental assays showed that substrate concentration and enzyme dosage strongly influenced both responses, whereas temperature had a moderate effect. The fitted models exhibited R²_adjusted values above 70% and met statistical assumptions, confirming their predictive reliability. Optimal conditions for maximizing DH were 55 °C, 50% w/w substrate, and 13 mAU/g protease, yielding a predicted DH of 6.65%. In contrast, the highest NR (48.35%) was observed at 50 °C, 50% w/w substrate, and 13 mAU/g protease, indicating that solubilization does not depend solely on hydrolysis intensity. Validation experiments showed no significant differences between predicted and experimental values (p > 0.05), supporting the robustness of the models. These results demonstrate the usefulness of RSM for optimizing enzymatic hydrolysis and advancing sustainable valorization of salmon by-products. Full article

Porcine blood meal is a protein and iron-rich animal by-product, but its use in companion animal diets is often limited by poor solubility and variable digestibility caused by thermal processing. This study evaluated whether enzymatic hydrolysis could improve the physicochemical properties, digestibility, iron-related characteristics, and antioxidant capacity of porcine blood meal for potential use in canine diets. Porcine blood meal was hydrolyzed using alcalase or pepsin under controlled conditions, and the resulting hydrolysates were characterized by degree of hydrolysis, electrophoretic peptide profiles, techno-functional properties, in vitro digestibility using a simulated canine gastrointestinal model, heme and non-heme iron fractions, and antioxidant activities. Alcalase treatment produced a higher degree of hydrolysis and more extensive peptide fragmentation than pepsin. Consistent with these structural changes, the alcalase hydrolysate exhibited significantly higher in vitro apparent digestibility. Enzymatic hydrolysis increased extractable heme iron while reducing ferrozine-reactive non-heme iron, suggesting changes in iron binding forms after proteolysis. Hydrolyzed samples also showed enhanced radical scavenging activity and ferric-reducing capacity, whereas superoxide dismutase (SOD)-like activity decreased following hydrolysis. These findings indicate that controlled enzymatic hydrolysis, particularly with alcalase, could improve apparent digestibility and non-enzymatic antioxidant capacity of porcine blood meal, supporting its potential as an iron-containing ingredient in canine diets. Further in vivo studies would be required to confirm iron availability and nutritional efficacy. Full article

Rice starch (RS) is widely consumed, but is usually rapidly digested, which may increase postprandial blood glucose levels. Therefore, regulating RS digestibility is important for development functional starch-based foods. In this study, sodium alginate (NaAlg) was incorporated into RS gels and subsequently crosslinked with Ca²⁺ to form a calcium alginate (CaAlg) network, and its effects on the physicochemical properties, digestion behavior, and physiological responses of RS gels were evaluated. Rheological measurement showed that the Ca²⁺-crosslinked alginate network increased the viscosity and viscoelastic moduli of RS gels. Low-field nuclear magnetic resonance analysis showed that the Ca²⁺-crosslinked alginate network reduced free water mobility. Structural characterization using Fourier-transform infrared spectroscopy, X-ray diffraction, and cold-field scanning electron microscopy shows that the Ca²⁺-crosslinked alginate network was associated with enhanced intermolecular interactions and a more continuous gel network, while all gelatinized samples exhibited predominantly amorphous structures. In vitro digestion experiments showed that the hydrolysis degree at 120 min decreased from 92.3% in RS to 85.6% in HCaAlg/RS. The rapidly digestible starch content significantly decreased from 72.4% to 68.4% (p < 0.05), while resistant starch significantly increased from 7.7% to 14.4% (p < 0.05). First-order kinetic fitting showed that C_∞ significantly decreased from 93.0% to 86.0%, and k significantly decreased from 0.027 to 0.013 min⁻¹ (p < 0.05). In vivo experiments showed that the Ca²⁺-crosslinked alginate/RS gels were associated with a lower postprandial glycemic response, with the incremental area under the curve significantly decreased from 747.2 to 591.7 mmol·min/L (p < 0.05), and the intestinal propulsion rate decreased from 89.6% to 75.3% (p < 0.05). These results suggest that Ca²⁺-crosslinked alginate network formation may modulate the structural properties, digestion behavior, and digestion-related physiological responses of RS gels, providing a basis for the development of starch-based functional foods with improved glycemic control. Full article

In the present study, starch extrudates with varying moisture contents (30%, 40%, and 50%) were prepared by twin-screw extrusion; the morphology, structural order changes, in vitro digestion, and fecal fermentation characteristics were investigated. X-ray diffraction (XRD) and differential scanning calorimetry (DSC) analyses demonstrated the extrusion process severely disrupted the starch order, while the addition of water reduced this disruptive effect. The long-range ordered structure of starch extrudates gradually decreased with the increasing moisture contents, indicating the damage degree of starch extrudates increased with increasing moisture content. Compared to high maize 260 (NS), extruded starch (ES) and starch extrudates with different moisture contents (S-30, S-40, and S-50) exhibited a significantly higher hydrolysis rate, digestion extent, and fermentation rate, while no significant differences were shown among starch extrudates with different moisture contents. Interestingly, compared to ES, starch extrudates with high moisture contents (S-30, S-40, and S-50) exhibited significant higher levels of short-chain fatty acids (SCFAs). Pearson correlation analysis showed the yields of SCFAs were positively correlated with the content of V-type starch formed during extrusion. These findings provide a theoretical guidance for the design of starch-based extruded foods with varying moisture contents. Full article

The Atlantic blue crab (Callinectes sapidus) is an invasive species widely distributed in the Mediterranean Sea, causing significant ecological and economic impacts. Despite its low commercial value and the limited utilization of undersized and non-marketable specimens, whole blue crab biomass represents a promising resource for the production of value-added compounds within a circular bioeconomy framework. In this study, whole blue crab biomass, including undersized individuals and non-marketable fractions, was directly valorized through enzymatic hydrolysis for the production of protein hydrolysates. Three commercial proteases (Alcalase, Neutrase, and Papain) were comparatively evaluated for protein hydrolysate production, and the hydrolysis conditions were assessed based on soluble matter yield. The evaluation of hydrolysis conditions identified pH 8, 50 °C, enzyme-to-substrate ratio of 2500 U g⁻¹, a solid-to-liquid ratio of 1:4, and a reaction time of 8 h as the most effective conditions for protein solubilization. Under these conditions, maximum soluble matter yields of 57.69% for Alcalase, 51.64% for Neutrase, and 48.44% for Papain were obtained. The obtained hydrolysates were subsequently characterized in terms of protein content and degree of hydrolysis (DH), both of which were significantly affected by enzyme type, following the order Alcalase (64.59 ± 0.75%) > Neutrase (62.29 ± 0.82%) > Papain (58.88 ± 0.65%). A similar trend was observed for degrees of hydrolysis (DH) of the products (43.20 ± 1.24%, 40.29 ± 1.05%, 37.26 ± 1.13%) respectively. Techno-functional properties of the hydrolysates were also enzyme-dependent and closely related to the extent of hydrolysis. Alcalase produced hydrolysates with higher DH, favoring the formation of smaller and more hydrophilic peptides, which enhanced water solubility (98.18 ± 0.51%) and antioxidant activity (77.08 ± 1.06%). In contrast, Papain-derived hydrolysates showed lower hydrolysis extent, likely preserving larger peptide structures and hydrophobic domains associated with higher emulsifying activity (16.10 ± 0.46 m² g⁻¹) and foaming capacity (30.47 ± 1.40%). Neutrase displayed intermediate behavior across most parameters. Overall, the results demonstrate that enzymatic hydrolysis of whole blue crab biomass is an effective valorization strategy, and that enzyme selection plays a key role in modulating hydrolysis efficiency and techno-functional properties. This approach provides a sustainable pathway for the management of invasive species while generating functional ingredients for food and nutraceutical applications. Full article

Enzymatic hydrolysis with proteases efficiently releases taste active and volatile compounds from mushroom matrices; however, how protease specificity impacts the flavor characteristics of Sarcodon imbricatus (S. imbricatus) remains unclear. In this study, S. imbricatus was treated with Flavourzyme, Protamex, and Bromelain to produce hydrolysates, and the resulting changes in non-volatile taste-active compounds and volatile flavor characteristics were systematically evaluated by free amino acid analysis, 5′-nucleotides determination, electronic tongue, and HS-GC-IMS. The results show that enzymatic hydrolysis significantly affects its flavor characteristics. Flavourzyme treatment resulted in the highest degree of hydrolysis (29.24 ± 0.65%) and free amino acid (47.46 ± 1.02 mg/g) accumulation, whereas Protamex produced the highest equivalent umami concentration (EUC) value (115.81 g MSG/100 g), indicating stronger umami synergism between amino acids and 5′-nucleotides. Bromelain also altered the flavor characteristics after hydrolysis, but to a lesser extent. Electronic tongue analysis further showed that enzymatic hydrolysis generally enhanced umami and reduced bitterness, with Flavourzyme exhibiting the most pronounced effect. Meanwhile, HS-GC-IMS identified 69 volatile compounds and showed that FSIH and PSIH had more pronounced effects on the volatile profiles of S. imbricatus. Furthermore, 16 discriminatory markers (VIP > 1) were screened, indicating distinct volatile modulation by different proteases. Overall, Flavourzyme exhibited the most balanced performance and was considered the preferable protease for S. imbricatus hydrolysis under the present conditions. These findings provide a theoretical basis for its further processing and natural seasoning development. Full article

This study investigated the optimization of the physicochemical properties of normal maize starch (NMS) by esterification with octenyl succinic anhydride (OSA). The synergistic effects of OSA addition time, temperature, and total reaction time on the degree of substitution (DS) and the physicochemical properties of starch were evaluated using a combination of single-factor experiments and Response Surface Methodology (RSM). FT-IR spectroscopy confirmed the successful incorporation of OSA groups into starch molecules, with the appearance of two characteristic absorption peaks at 1724 and 1572 cm⁻¹. Single-factor experiments revealed that a temperature of 40 °C, an OSA addition time of 2 h, and a total reaction time of 6 h effectively maximized the DS. These conditions balanced efficient esterification with the suppression of OSA hydrolysis and droplet aggregation. The resulting optimized OSA starch displayed lower gelatinization temperature and enthalpy, higher viscosity, more pronounced shear-thinning behavior, and greater resistance to retrogradation. Pearson correlation and simple linear regression analyses demonstrated that DS was negatively correlated with both ΔH and G′_max. The RSM model accurately predicted the optimal synthesis parameters (41.96 °C, 2.25 h OSA addition time, 6.9 h total reaction time), achieving a validated DS of 0.0258. This study provides valuable insights for producing starch-based additives in complex food systems. Full article

Over the past decade, changes in consumer dietary habits have driven an increasing demand for protein-enriched confectionery products. Consequently, research has increasingly focused on the utilization of alternative protein origins, including Acheta domesticus. This research paper aims to characterize Acheta domesticus protein powder (CP) in terms of its functional properties and chemical composition. In addition, the amino acid profile was determined using HPLC, while antioxidant capacity was evaluated by spectrophotometric methods (including the ABTS assay). Edibility was further assessed in proteins, both in their native form and after incorporation into cocoa cream products, using an in vitro digestion model. The results indicated that methionine was the most abundant essential amino acid in CP (17.71 mg/100 g protein), while glycine was the predominant non-essential amino acid (42.38 mg/100 g protein). CP also demonstrated high solubility (80.00%) and notable water- and oil-binding capacities (90.26% and 94.87%, respectively). However, its emulsifying properties were limited, as emulsifying stability was maintained for only 26 min. In contrast, digestibility results indicated strong protein hydrolysis in both native and cocoa cream samples enriched with CP in different concentrations (10, 12.5 and 15%), hereafter designated as CPC10, CPC12.5, and CPC15. The degree of hydrolysis was higher after the digestion process, with 39.11% for the control and 47.14%, 48.62% and 50.05% for the fortified samples—CPC10, CPC12.5 and CPC15, respectively. The ABTS assay further confirmed the increase in antioxidant activity after digestion. The ABTS values of the digested fortified samples ranged from 20.91% for CPC10 to 40.45% for CPC15, suggesting the release of bioactive peptides during gastrointestinal digestion. Overall, the findings highlight CP as a promising protein source for the fortification of cocoa cream products, which are naturally low in protein content. Full article

The rising global demand for protein-rich food has intensified interest in alternative and sustainable protein sources. Insects, particularly black soldier fly (BSF) larvae, represent promising substrates due to their high nutritional content and potential for valorization into functional ingredients. This study investigated the impact of pre-hydrolysis treatments on the efficiency of enzymatic hydrolysis using alcalase to enhance protein solubilization and bioactive peptide production. Pre-treatments included organic acids (propionic and acetic acid) and a pressure-thermal method. Results indicated that BSF larvae responded differently to the evaluated pre-treatment strategies. Notably, the pressure-thermal treatment combined with enzymatic hydrolysis increased soluble protein content by approximately 30% and antioxidant activity by approximately 20%, suggesting enhanced release of bioactive peptides. Although organic acid treatments increased protein solubility, they did not improve the degree of hydrolysis or antioxidant activity. These findings highlight the potential of pressure-thermal pre-treatment to improve the efficiency of protein extraction from insect biomass and support the integration of such approaches into food bioprocessing strategies aimed at developing novel, high-value protein ingredients. Full article

In our preliminary work, a clam sauce prepared by fermentation with Aspergillus oryzae 3.042 (AO) exhibited desirable flavor and quality; however, the process was prolonged (exceeding 30 d), and a high salt concentration (6–15%) was necessary to prevent spoilage. Consequently, shortening production cycle and reducing salt content without compromising product quality became a new objective. Enzymatic hydrolysis has long been recognized as an efficient approach in seasoning production, with enzyme efficacy being a key competitive factor. Accordingly, an AO-derived aminopeptidase–protease complex (AOAP) was optimized and prepared as a preparatory step. In this study, AOAP was applied to hydrolyze clam meat to evaluate its potential for producing a seasoning base. A two-step enzymatic hydrolysis process was employed. In the first step, the highest hydrolysis degree (29.1%) was achieved using alkaline protease (AP). The resulting hydrolysate was subsequently subjected to secondary hydrolysis with AOAP, achieving a degree of hydrolysis as high as 49.8%. Sensory evaluation revealed a significant reduction in bitterness and enhancement of umami in the final hydrolysate, a finding corroborated by electronic tongue analysis. Further characterization via LC-MS and amino acid (aa) analysis showed that a substantial number of bitter and umami peptides were released following AP treatment; however, the number of these peptides was markedly reduced after a subsequent AOAP hydrolysis, with concurrent substantial changes in the peptide profile. In the two-step hydrolysate, umami peptides mostly contain 3–10 aa, whereas bitter peptides typically contain only 3–5 aa. The content of free aa increased from 369.17 mg/100 g in the control to 3026.25 mg/100 g in the two-step hydrolysate, half of which were bitter, indicating the debittering efficiency of AOAP. Electronic nose analysis revealed similar flavor profile and characteristic presence of nitrogen oxides in all hydrolysates. GC-MS analysis further demonstrated that, after combined enzymatic hydrolysis, the short-chain aldehydes and ketones responsible for the fishy odor in the raw material almost completely disappeared, while long-chain aldehydes with pleasant aromas were generated. These findings suggest that the secondary hydrolysis step using AOAP can effectively improve the overall flavor profile of the clam hydrolysate, which may support its potential applicability in seasoning production, though further optimization and scale-up validation are needed. Full article

Collagen-derived products are widely applied in functional foods; however, limited information is available regarding how different preparation methods, particularly thermal degradation and enzymatic hydrolysis, affect their anti-aging efficacy and biological functions. In this study, sturgeon skin was used as raw material to prepare gelatin–peptide complexes via thermal degradation (GPC-TD) and enzymatic hydrolysis (GPC-EH), and their comparative anti-aging and biological effects were evaluated in D-galactose-induced aging mice. Female ICR mice were divided into eight groups: a blank control group (normal saline), an aging model group (D-galactose, 500 mg/kg), three GPC-TD and three GPC-EH groups (D-galactose supplemented with 100, 200, 400 mg/kg GPC-TD or GPC-EH). After eight weeks of administration, various physiological parameters were evaluated. Throughout the experiment, no statistically significant difference in body weight (BW) was observed among the groups; however, the blank and model groups consistently maintained the highest BW. The medium- and high-dose GPC-TD groups showed relatively faster weight gain, whereas the 100 mg/kg GPC-TD group and all three GPC-EH groups exhibited the slowest BW gain. Notably, the gastric indices of these latter groups were significantly lower than those of other groups (p < 0.05), which might be a key factor affecting BW gain. Behavioral tests revealed that the model group exhibited significantly reduced swimming speed and weakened nesting ability (p < 0.05), both of which were alleviated to varying degrees by treatment with GPC-TD and GPC-EH. Furthermore, both complexes markedly decreased malondialdehyde content in liver tissue (p < 0.05). Compared with the model group, high-dose GPC-TD and GPC-EH effectively increased acetylcholine content and inhibited acetylcholinesterase activity (p < 0.05). Masson staining revealed abnormal collagen fibers accumulation in certain tissues of model mice, a condition that was clearly ameliorated by GPC-TD and, to a greater extent, by GPC-EH. In addition, medium and high doses of both complexes significantly protected against D-galactose-induced loss of Nissl bodies in brain neurons; in the high-dose GPC-EH group, the density and number of Nissl bodies approached those observed in the blank group. These findings suggest that both GPC-TD and GPC-EH possess potential anti-aging effects, with GPC-EH exhibiting superior efficacy. This study provides theoretical support for consumers, the catering industry, and manufacturers in selecting appropriate processing techniques for the preparation of sturgeon skin GPC. Full article

The sustainable management of intensive swine farming is currently bottlenecked by the difficult valorization of metal-rich wastewater sludge. The structural rigidity of this sludge, stabilized by divalent cation bridging, severely limits its anaerobic digestion and overall resource recovery. To optimize the manure management chain, this study comprehensively evaluated various physical and chemical pretreatments to identify the most effective disintegration strategy for enhanced volatile fatty acid (VFA) production. Among the tested conditions, the coupling of thermal hydrolysis with citrate chelation (T/SC) was the most effective, achieving the highest disintegration degree (12.37%) and biopolymer solubilization. Mechanism analysis revealed that, unlike traditional alkaline treatments, which are limited by the severe reprecipitation of magnesium and phosphate, citrate effectively sequestered bridging cations (Ca²⁺ and Mg²⁺) via ligand exchange. This synergistic disintegration accelerated the fermentation kinetics, enhancing the total VFA yield 2-fold (1293 mg/L) compared to the control group while maintaining a high-value, butyrate-dominant product profile. These findings demonstrate that targeting ionic bridges via ligand-promoted dissolution provides a highly practical and sustainable strategy to maximize resource recovery and nutrient cycling from metal-laden livestock wastes. Full article

Chronic low-grade inflammation, a key driver of diabetes and fatty liver disease, is present in obesity, which affects 2.1 billion adults as of 2021. Plant-derived bioactive peptides have emerged as promising alternatives to treat inflammation in these pathological processes. This study evaluated the effect of pre- and post-ultrasound-assisted enzymatic hydrolysis on bioactive peptide production and antioxidant activity from common bean (Phaseolus vulgaris L.) and pumpkin (Cucurbita argyoesperma) seed proteins. Pre-treated hydrolysates were fractionated by molecular weight (<3 kDa and 3–10 kDa) and evaluated for their anti-inflammatory properties by measuring nitric oxide and reactive oxygen species in three treatment schemes (pre-, co-, and post-treatment) in an obesity/inflammatory macrophage model. Ultrasound pre-treatment achieved a higher degree of hydrolysis (peptide production) compared to post-treatment, with corresponding increases in antioxidant activity as measured by the ABTS and ORAC assays. All hydrolysate fractions demonstrated dose-dependent inhibition of pro-inflammatory markers. Fractions administered as a co-treatment showed the strongest anti-inflammatory effect, reducing Nos-2 and Cox-2 mRNA expression, as well as secreted levels of pro-inflammatory cytokines (TNF-α, IL-6, MCP-1). These findings indicate that ultrasound treatment, mainly as pre-treatment, represents an effective strategy for producing bioactive peptide hydrolysates with anti-inflammatory properties in vitro that warrant deeper investigation. Full article

Lipolysis is an interfacial reaction. Lecithins are natural emulsifiers containing a mixture of phospholipids (PL). Lecithin composition can be modified via enzymatic hydrolysis of PLs to produce lysophospholipids (LPL). The quantities of PL and LPL and the PL/LPL ratio are related to the emulsifying properties and interfacial activity of digestive lipases. This study aims to: (i) produce oil-in-water nanoemulsions of rapeseed oil (RSO) with soybean lecithin (SBL) and hydrolyzed lecithin (HL) at different concentrations and homogenization pressures and measure the mean droplet diameter (MDD) and polydispersity index (PdI) by dynamic light scattering; (ii) hydrolyze the emulsions in vitro with intestinal extracts of rainbow trout and estimate the degree of hydrolysis of lipids (DH) by the pH-stat method; and (iii) model the results on MDD, PdI, and DH through the response surface methodology (RSM). When HL was used as an emulsifier, DH, MDD, and PdI were fitted to polynomial quadratic, two-factor interaction, and linear models, respectively. MDD, PdI, and DH were fitted to polynomial quadratic SBL models. The optimal conditions were emulsifier concentrations of 0.45% and 0.76% w/w and homogenization pressures of 10,790 and 10,781 psi for HL and SBL, respectively. Under these conditions, DH = 34.9% and 33.08%, MDD = 241.9 and 543.6 nm, and PdI = 0.29 and 0.52 for HL and SBL, respectively. Full article