Long-Term Casein-Bound Lactulosyllysine Consumption Induced Nonobese Nonalcoholic Fatty Liver Disease by Promoting Carbonyl Glycation in the Liver of C57BL/6 Mice.

Lactulosyllysine (LL) is abundant in thermally processed dairy products, with its concentration increasing in response to more intense heat treatment. However, there are limited studies on the potential harmful effects of LL on human health. This study investigated the negative impact of casein-bound LL on liver health by feeding healthy C57BL/6 mice diets containing varying levels of casein-bound LL. After 16 weeks of LL diet administration, mice exhibited a nonobese nonalcoholic fatty liver disease (NONAFLD) phenotype, characterized by reduced body weight gain, hypolipidemia, and intrahepatic lipid accumulation. Nontarget metabolomic analysis showed that casein-bound LL induced alterations in plasma levels of compounds associated with lipid degradation. Mechanistically, casein-bound LL may impair the function of 5'-adenosine monophosphate-activated protein kinase and apolipoprotein B100 by inducing dicarbonyl stress, thereby promoting carbonyl glycation in the liver. Consequently, the long-term consumption of LL-rich dairy products may be a contributing factor to the risk of developing NONAFLD.

Nerve injury augments Cacna2d1 transcription via CK2-mediated phosphorylation of the histone deacetylase HDAC2 in dorsal root ganglia.

Development of chronic neuropathic pain involves complex synaptic and epigenetic mechanisms. Nerve injury causes sustained upregulation of α2δ-1 (encoded by the Cacna2d1 gene) in the dorsal root ganglion (DRG), contributing to pain hypersensitivity by directly interacting with and augmenting presynaptic NMDA receptor activity in the spinal dorsal horn. Under normal conditions, histone deacetylase 2 (HDAC2) is highly enriched at the Cacna2d1 gene promoter in the DRG, which constitutively suppresses Cacna2d1 transcription. However, nerve injury leads to HDAC2 dissociation from the Cacna2d1 promoter, promoting the enrichment of active histone marks and Cacna2d1 transcription in primary sensory neurons. In this study, we determined the mechanism by which nerve injury diminishes HDAC2 occupancy at the Cacna2d1 promoter in the DRG. Spinal nerve injury in rats increased serine-394 phosphorylation of HDAC2 in the DRG. Coimmunoprecipitation showed that nerve injury enhanced the physical interaction between HDAC2 and casein kinase II (CK2) in the DRG. Furthermore, repeated intrathecal treatment with CX-4945, a potent and specific CK2 inhibitor, markedly reversed nerve injury-induced pain hypersensitivity, HDAC2 phosphorylation, and α2δ-1 expression levels in the DRG. In addition, treatment with CX-4945 largely restored HDAC2 enrichment at the Cacna2d1 promoter and reduced the elevated levels of acetylated H3 and H4 histones, particularly H3K9ac and H4K5ac, at the Cacna2d1 promoter in the injured DRG. These findings suggest that nerve injury increases CK2 activity and CK2-HDAC2 interactions, which enhance HDAC2 phosphorylation in the DRG. This, in turn, diminishes HDAC2 enrichment at the Cacna2d1 promoter, thereby promoting Cacna2d1 transcription.

Encapsulation of Lactiplantibacillus plantarum probiotics through cross-linked chitosan and casein for improving their viability, antioxidant and detoxification.

In the present study, encapsulation of Lactiplantibacillus plantarum (L.p) was performed using chitosan and casein through calcium phosphate intercrossing. Chitosan and casein both considered as non-toxic and biocompatible food derived components with intrinsic antioxidant properties. Layer by layer strategy was performed for deposition of modified cross-linked chitosan along with casein as the novel protective layers on the surface of probiotics. After confirmation of successful encapsulation, the viability and antioxidant activity of encapsulated L.p was evaluated. The results showed enhanced survival and antioxidant activity of encapsulated L.p compared to free bacteria in simulated digestive conditions. The survival of free and encapsulated L.p was respectively 1.38 ± 0.29 log cfu/ml and 6.99 ± 0.12 log cfu/ml in SGF and 8.54 ± 0.05 log cfu/ml and 7.25 ± 0.23 log cfu/ml in SIJ after 2 h of incubation. HPLC analysis was also used to investigate the detoxification activity of probiotics toward Aflatoxin M1 and obtained results showed encapsulated bacteria could significantly reduce aflatoxin M1 (68.44 ± 0.5 %) compared to free bacteria (43.76 ± 0.54 %). The results of this research suggest that the chitosan/casein mediated encapsulation of L.p with layer-by-layer technology is an effective method to improve the survival and antioxidant properties of probiotics with enhanced detoxification of AFM1.

Heat-induced interactions between microfluidized hemp protein particles and caseins or whey proteins.

The rising demand for sustainable proteins leads to increased interest in plant proteins like hemp protein (HP). However, commercial HP's poor functionality, including heat aggregation, limit its use. This study explored the heat-induced interactions of hemp protein particles (HPPs) with milk proteins, specifically whey proteins and caseins. Using various analysis techniques-static light scattering, TEM, SDS electrophoresis, surface hydrophobicity, and free sulfhydryl content-results showed that co-heating HPPs with whey protein isolate (WPI) or sodium caseinate (NaCN) at 95 °C for 20 min reduced HPPs aggregation. HPPs/WPI particles had a d4,3 of ∼3.8 µm, while HPPs/NaCN were ∼1.9 µm, compared to ∼27.5 µm for HPPs alone. SDS-PAGE indicated that whey proteins irreversibly bound to HPPs, through disulfide bonds, whereas casein bound reversibly, possibly involving the chaperone-like property of casein. This study proposes possible mechanisms by which HPPs interact with milk proteins and impact protein aggregation. This may provide opportunities for developing hybrid protein microparticles.

Effects of Casein-Derived Peptide Met-Lys-Pro on Systolic and Diastolic Blood Pressure: A Randomized, Double-Blind, Placebo-Controlled, Parallel-Group Study.

Hypertension is defined as a systolic blood pressure (SBP) of over 140 mmHg or diastolic blood pressure (DBP) of over 90 mmHg. Hypertension is widely known to be a factor affecting human health, so its prevention is considered important. We investigated the effect of casein-derived tripeptide Met-Lys-Pro (MKP) on blood pressure in a randomized, placebo-controlled, parallel-group study. Participants were healthy adults with SBP between 120 and 139 mmHg, and/or DBP between 80 and 89 mmHg. A total of 121 participants were randomly assigned to the MKP group or placebo group. Participants received either a test powder containing 100 µg of MKP or a placebo powder without MKP for 12 weeks. As a result, SBP and DBP were significantly lower in the MKP group than in the placebo group. No adverse events associated with the MKP intake were observed. This study showed that MKP has a beneficial effect on lowering blood pressure in healthy adults with high-normal and elevated blood pressure and can be safely used for continuous intake.

Photonic Dipstick Immunosensor to Detect Adulteration of Ewe, Goat, and Donkey Milk with Cow Milk through Bovine κ-Casein Detection.

The quality and authenticity of milk are of paramount importance. Cow milk is more allergenic and less nutritious than ewe, goat, or donkey milk, which are often adulterated with cow milk due to their seasonal availability and higher prices. In this work, a silicon photonic dipstick sensor accommodating two U-shaped Mach-Zehnder Interferometers (MZIs) was employed for the label-free detection of the adulteration of ewe, goat, and donkey milk with cow milk. One of the two MZIs of the chip was modified with bovine κ-casein, while the other was modified with bovine serum albumin to serve as a blank. All assay steps were performed by immersion of the chip side where the MZIs are positioned into the reagent solutions, leading to a photonic dipstick immunosensor. Thus, the chip was first immersed in a mixture of milk with anti-bovine κ-casein antibody and then in a secondary antibody solution for signal enhancement. A limit of detection of 0.05% v/v cow milk in ewe, goat, or donkey milk was achieved in 12 min using a 50-times diluted sample. This fast, sensitive, and simple assay, without the need for sample pre-processing, microfluidics, or pumps, makes the developed sensor ideal for the detection of milk adulteration at the point of need.

Structural changes and in vitro bioaccessibility of CPP-febisgly complexes: Dependence on iron load.

The effect of casein phosphopeptides (CPP) and ferrous bisglycinate (FebisGly) at different ratios (1:20, 1:10, and 1:5 w/w) on iron supplementation was investigated. The in vitro bioaccessibility, structural changes, antioxidant activity, and the effect of absorption inhibitors were also explored. The results demonstrated that CPP enhanced the bioaccessibility of FebisGly by 68.72 % ± 0.18 % and increased the ß-sheet content from 21.60 % ± 0.23 % to 67.92 % ± 0.12 %, forming a stable secondary structure. The particle size distribution (PSD) and rheological analyses indicated that CPP significantly contributed to the formation of chelated irons, resulting in a uniform PSD and enhanced viscoelasticity. Moreover, it prolonged the gastric emptying time, reducing gastric irritation further. The carboxyl and amino groups in the CPP molecules participated in chelation reaction, improved the antioxidant activity, and competed with phytic acid, tannic acid, and cellulose for iron. Overall, these results laid a foundation for developing novel iron supplementation strategies.

In-vitro and in-vivo comparative studies of treatment effects on enamel demineralization during orthodontic therapy: implications for clinical early-intervention strategy.

OBJECTIVES: This study aimed to investigate if CPP-ACP / infiltrating resin was superior in treating enamel demineralization during orthodontic therapy compared with fluoride varnish, in order to provide early-intervention implications for dental professionals. MATERIALS AND METHODS: In the in-vitro study, premolars were grouped into four: remineralization with fluoride varnish / CPP-ACP, sealing with infiltrating resin, and negative control. Experimental demineralization of enamel surfaces was analyzed using techniques of QLF, SEM, EDS and micro-hardness testing. An in-vivo intervention study was conducted on patients randomly assigned into three groups. At the baseline and every-3-month follow-up, QLF parameters were compared temporally and parallelly to yield potential implications for promotion in clinical practice. RESULTS: The in-vitro study performed on 48 experimental tooth surfaces demonstrated that sealing with infiltrating resin reduced enamel surface porosity and increased surface micro-hardness significantly. In the in-vivo intervention study on 163 tooth surfaces, it was suggested that for those who meet the criteria of -10 < ΔF < -6 and - 1000 < ΔQ < -20 at the baseline, all these treatment methods could achieve acceptable outcomes; with the rising of absolute values of ΔF and ΔQ, sealing with infiltrating resin showed more evident advantages. CONCLUSION: For enamel demineralization during orthodontic therapy, all the treatment methods involved in this study showed acceptable effectiveness but had respective characteristics in treatment effects. QLF parameters could be used as indicators for clinical early-intervention strategy with regards to this clinical issue. CLINICAL RELEVANCE: With QLF parameters, clinical early-intervention strategy for enamel demineralization during orthodontic therapy could be optimized.

An Overview of Interactions between Goat Milk Casein and Other Food Components: Polysaccharides, Polyphenols, and Metal Ions.

Casein is among the most abundant proteins in milk and has high nutritional value. Casein's interactions with polysaccharides, polyphenols, and metal ions are important for regulating the functional properties and textural quality of dairy foods. To improve the functional properties of casein-based foods, a deep understanding of the interaction mechanisms and the influencing factors between casein and other food components is required. This review started by elucidating the interaction mechanism of casein with polysaccharides, polyphenols, and metal ions. Thermodynamic incompatibility and attraction are the fundamental factors in determining the interaction types between casein and polysaccharides, which leads to different phase behaviors and microstructural types in casein-based foods. Additionally, the interaction of casein with polyphenols primarily occurs through non-covalent (hydrogen bonding, hydrophobic interactions, van der Waals forces, and ionic bonding) or covalent interaction (primarily based on the oxidation of proteins or polyphenols by enzymatic or non-enzymatic (alkaline or free radical grafting) approaches). Moreover, the selectivity of casein to specific metal ions is also introduced. Factors affecting the binding of casein to the above three components, such as temperature, pH, the mixing ratio, and the fine structure of these components, are also summarized to provide a good foundation for casein-based food applications.

New Insights into the Structure-Activity Relationship of a Novel Immunomodulatory Peptide (HPHPHLSF) from Casein Hydrolyzed by Kluyveromyces marxianus JY-1: Molecular Docking, Interaction Evaluation, and HOMO Analysis.

Casein is rich in immunomodulatory peptides. In this study, the release of casein-derived immunomodulatory peptides by Kluyveromyces marxianus JY-1 was investigated for the first time, and an immunosuppressive mouse model was used to evaluate the immunomodulatory activity in the casein hydrolysate. The results showed that the cellular and humoral immunity of immunosuppressed mice could be significantly enhanced by casein hydrolysate. Peptide HPHPHLSF with high immunomodulatory activity from casein hydrolysate was screened using the virtual screening technique. HPHPHLSF possessed strong immunomodulatory activity and significantly upregulated the expression of IL-6, IL-1ß, and TNF-α. Next, the interaction of HPHPHLSF with TLR2/4 on the cell surface of RAW264.7 cells was further elucidated by molecular docking and combined analysis of double-stranded small interfering RNA and receptor inhibitors. Further, the results of the highest occupied molecular orbital energy distribution elucidated that the histidine active site C48═O49 played an important role in the immunomodulatory activity of HPHPHLSF. This study confirmed that casein hydrolyzed by K. marxianus JY-1 was a natural immunomodulator, while the structure-activity relationship analysis provided new theoretical and technical support for the targeted preparation and screening of casein-derived immunomodulatory peptides.

Design of casein-based nanocarriers for targeted delivery of daunorubicin to leukemia cells.

Daunorubicin (DAU) is a chemotherapy drug approved for the treatment of some cancers. However, the clinical compatibility of DAU is limited due to its lack of specificity and its highly toxic effects, which interfere with normal cells. This toxicity can be reduced with nanocarriers and targeted drug delivery systems. In this study, to develop the drug delivery of DAU, the surface of synthesized nanoparticles was modified by folic acid to target cancer cells optimally. Encapsulation of DAU in protein sodium caseinate (NaCAS) was done by adding calcium ions to bring the casein (CAS) in the solution to a micellar structure to synthesize dense nanoparticles. Fourier-transform infrared spectroscopy transmission, fluorescence spectroscopy, UV-Vis spectroscopy, field emission scanning electron microscopy, and zeta potential studies designed and distinguished the synthesized nanocomplexes. The results showed that CAS nanoparticles successfully encapsulated DAU, and the protein surface was targeted by folic acid. Light scattering analysis determined that the particles with a scattering index number of 306.0 and an average size of 8.117 nm were synthesized. The zeta potential of CAS micelles is more harmful than CAS nanoparticles. This is because calcium ions are added during the formation of CAS nanoparticles during the drug-loading stages. These studies prove that the synthesized "NaCAS-DAU" and "NaCAS-DAU-folic acid" complexes can be favorable carriers in the targeted drug delivery of cancer drugs.

Transglutaminase Crosslinked Milk Protein Concentrate and Micellar Casein Concentrate: Impact on the Functionality of Imitation Mozzarella Cheese Manufactured on a Small Scale Using a Rapid Visco Analyzer.

In dairy-based imitation mozzarella cheese (IMC) formulations, intact casein is critical and imparts IMC with a firm and elastic, stringy, melted texture. Rennet casein (RCN) is the desired ingredient to provide intact casein in IMC and is preferred over milk protein concentrate (MPC) and micellar casein concentrate (MCC). Transglutaminase (TGase), a crosslinking enzyme, alters the physical properties of MPC or MCC and may change IMC functionality. The objective of this study was to determine the effect of TGase-crosslinked MPC and MCC powders on the functionality of IMCs. The TGase treatment included TGase at 0.3 (L) and 3.0 (H) units/g of protein and a control (C) with no TGase addition. Each IMC formulation was balanced for constituents and was produced in a Rapid Visco Analyzer (RVA). The MCC or MPC powder with high TGase enzyme in IMC formulation did not form an emulsion. The IMC containing TGase-treated powders had a significantly (p ≤ 0.05) higher RVA-viscosity during manufacture and transition temperature (TT), and a significantly (p ≤ 0.05) lower Schreiber melt test area. The IMC made from MPC (with or without TGase) had lower TT values and Schreiber melt test area as compared with that made from MCC. The TGase-treated MPC and MCC, when used for IMC manufacture, were comparable to IMC manufactured with RCN in texture and some measured melted characteristics. In conclusion, TGase treatment alters the melt characteristics of MCC and MPC in IMC applications.

Oil-water interfacial behaviour of different caseins and stability of emulsions: Effect of micelle content and caseins concentrations.

This study aimed to investigate the interfacial behaviour of caseins in different micelle content and its effect on the stability of emulsions, including micellar casein concentrate (MCN), calcium caseinate (CaC) and sodium caseinate (NaC). Results revealed that at high protein concentrations (0.5 %-2.5 %), MCN, CaC and NaC exhibited similar interfacial behaviour as well as unfolding rate constants (k 1 ) of 3.11-3.41 × 10-4 (s-1), 2.96-3.35 × 10-4 (s-1) and 2.75-3.27 × 10-4 (s-1), respectively. The interfacial layer formed was dominated by non-micelles, and microscopic images revealed the thickness of the interfacial layer to be 10-20 nm. By contrast, at low concentrations, the differences in the slope of E-π curves and k 1 indicated that the micelle content of casein affects protein interfacial behaviour and properties and that micellar casein is involved in the formation of the interfacial layer. The formation of large numbers of droplets during emulsion preparation results in a similar low concentration environment. Cryo-TEM showed adsorption of micellar casein in all three casein-stabilised emulsions, and the amount of adsorption was proportional to the micelle content. NaC has faster adsorption and rearrangement rates due to fewer micelles and more non-micelles, so that NaC forms smaller droplets and more stable emulsions than those formed by MCN and CaC within the range of 0.5 % to 2.0 %.

Effect of UHT Thermal Treatment on the Secondary Structures of Milk Proteins: Insights From FTIR Analysis and Potential Allergenic Activity.

Although thermal treatments are beneficial for the preservation and safety of milk, they can also alter its immunogenic activity by affecting its protein components. To achieve precise results, it is essential to identify the specific proteins that cause food allergies. Therefore, investigating the possible alterations of cow's milk proteins (CMPs) resulting from thermal treatments is necessary. In this study, the Fourier transform infrared spectroscopy (FTIR) technique was used to analyze the effect of UHT thermal treatment on the secondary structures of milk casein. Using the second derivative, six characteristic peaks were identified in the Amide I region, ranging from 1700 to 1600 cm-1. It was found that thermal treatments produce shifts in absorption peaks, indicating changes in protein conformation and possibly in allergenic activity. These shifts were clearly identified in the first characteristic peak of samples M8 and M9, from 1621 to 1600 cm-1. The results suggest that thermal treatments may promote protein aggregation by increasing ß turns and reducing ß sheets and α helices, which could enhance the allergenic potential of the proteins and facilitate the formation of complexes between different milk proteins, such as ß-lactoglobulin and κ-casein. Further studies are needed to experimentally validate the allergenic activity of proteins modified by thermal treatments, as only an analytical method (FTIR) was used to evaluate the secondary structures of the proteins.

In vitro digestion and functional properties of bovine ß-casein: A comparison between adults and infants.

Gastrointestinal digestibility behavior, structural and functional characteristics of bovine ß-casein (ß-CN) were studied in vitro under infant and adult conditions. This direct comparison helps reveal the effects of different physiological stages on the digestive behavior of ß-CN. Not only was the degree of hydrolysis (DH) of ß-CN analyzed, but also the changes in its digestive morphology, microstructure, and secondary structure during digestion were explored in depth. Meanwhile, we focused on the physicochemical properties of ß-CN digesta, including solubility, emulsifying and foaming properties, as well as their functional properties, such as antimicrobial and antioxidant activities. Key results showed that ß-CN underwent more extensive hydrolysis in the adult digestion model, with approximately twice the DH compared to the infant model. The adult model exhibited faster digestion kinetics, less protein flocculation, and a more loosened secondary structure, indicating a more efficient digestion process. Notably, the digesta from the adult model displayed significantly improved solubility and emulsifying properties, and also enhanced antioxidant capacities, with significantly better inhibition of two common pathogenic bacteria than the infant model, and an average increase in the diameter of the inhibition zone of approximately 2 mm. These findings underscore the differential digestive behavior and functional potential of ß-CN across physiological stages. This comprehensive assessment approach contributes to a more comprehensive insight into the digestive behavior of ß-CN. Therefore, we conclude that producing products from unmodified ß-CN may be more suitable for the adult population, and that the digesta in the adult model exhibit higher functional properties.

Adding calcium phosphate agents alongside fluorides may enhance caries prevention and remineralization, although evidence is limited.

ARTICLE TITLE AND BIBLIOGRAPHIC INFORMATION: Effectiveness of Calcium Phosphate derivative agents on the prevention and remineralization of caries among children- A systematic review & meta-analysis of randomized controlled trials. Singal K, Sharda S, Gupta A, Malik VS, Singh M, Chauhan A, Agarwal A, Pradhan P, Singh M. J Evid Based Dent Pract. 2022; 22(3):101746. SOURCE OF FUNDING: Indian Council of Medical Research. TYPE OF STUDY/DESIGN: Systematic review with meta-analysis.

Casein phosphopeptide/antimicrobial peptide co-modified SrTiO3 nanotubes for prevention of bacterial infections and repair of bone defects.

Endowing titanium surfaces with multifunctional properties can reduce implant-related infections and enhance osseointegration. In this study, titanium dioxide nanotubes with strontium doping (STN) were first created on the titanium surface using anodic oxidation and hydrothermal synthesis techniques. Next, casein phosphopeptide (CCP) and an antimicrobial peptide (HHC36) were loaded into the STN with the aid of vacuum physical adsorption (STN-CP-H), giving the titanium surface a dual function of "antimicrobial-osteogenic". The surface of STN-CP-H has a suitable roughness and good hydrophilicity, which is conducive to osteoblasts. STN-CP-H had a 99 % antibacterial rate against S. aureus and E. coli and effectively prevented the growth of bacterial biofilm. Meanwhile, the antibacterial mechanism of STN-CP-H was initially explored with the help of transcriptome sequencing technology. STN-CP-H could greatly increase osteoblast adhesion, proliferation, and expression of osteogenic markers (alkaline phosphatase, runt-related transcription) when CCP and Sr worked together synergistically. In vivo, the STN-CP-H coating could effectively promote new osteogenesis around titanium implant bone and had no toxic effects on heart, liver, spleen, lung and kidney tissues. A potential anti-infection bone healing material, STN-CP-H bifunctional coating developed in this work efficiently inhibited bacterial infection of titanium implants and encouraged early osseointegration.

Casein kinase 1α mediates estradiol secretion via CYP19A1 expression in mouse ovarian granulosa cells.

BACKGROUND: Casein kinase 1α (CK1α), expressed in both ovarian germ and somatic cells, is involved in the initial meiosis and primordial follicle formation of mouse oocytes. Using in vitro and in vivo experiments in this study, we explored the function and mechanism of CK1α in estrogen synthesis in mice ovarian granulosa cells. METHODS: A CK1α knockout (cKO) mouse model, targeted specifically to ovarian granulosa cells (GCs), was employed to establish the influence of CK1α on in vivo estrogen synthesis. The influence of CK1α deficiency on GCs was determined in vivo and in vitro by immunofluorescence analysis and Western blot assay. Transcriptome profiling, differentially expressed genes and gene functional enrichment analyses, and computation protein-protein docking, were further employed to assess the CK1α pathway. Furthermore, wild-type female mice were treated with the CK1α antagonist D4476 to elucidate the CK1α's role in estrogen regulation. RESULTS: Ovarian GCs CK1α deficiency impaired fertility and superovulation of female mice; also, the average litter size and the estradiol (E2) level in the serum of cKO female mice were decreased by 57.3% and 87.4% vs. control mice, respectively. This deficiency disrupted the estrous cycle and enhanced the apoptosis in the GCs. We observed that CK1α mediated the secretion of estradiol in mouse ovarian GCs via the cytochrome P450 subfamily 19 member 1 (CYP19A1). CONCLUSIONS: These findings improve the existing understanding of the regulation mechanism of female reproduction and estrogen synthesis. TRIAL REGISTRATION: Not applicable.

Novel hydroxyl-terminated hyperbranched polymer as a synergistic modifier with tannin for preparation of casein-based films with superior performance.

A hyperbranched poly (titanium oxide) (HBPTi) with hydroxyl terminal groups was synthesized via polycondensation reaction as a synergistic modifier with tannin to promote performance of casein-based composite film. The synergistic effects of HBPTis, acquiring different hyperbranched structures, with tannin on the microstructure, mechanical characteristics, barrier against water vapor, and thermal stability of casein-based film were investigated in this work. The tensile strength of the composite films increased from 7.6 MPa to 22.1 MPa, which accounts for 190.79 % increase after the addition of HBPTi compared to casein-tannin films modified with glycerol. The casein-tannin films with the help of HBPTi presented excellent water vapor permeation, thermal stability, and showed nearly 100 % UV absorption in the range 200-400 nm. Additionally, the microstructure of HBPTi modified casein-tannin films tend to be more compact due to the promoted interaction of casein-tannin composite aided by covalent bonding and/or other types of bonding between casein, tannin and HBPTi. Therefore, associative modification using such hyperbranched polymers and tannins provides extendable application value for casein-based films especially as food packaging materials and for other fields as well.

Exploring structural features of sleep-enhancing peptides derived from casein hydrolysates by chemometrics and random forest methodology.

Milk casein is regarded as source to release potential sleep-enhancing peptides. Although various casein hydrolysates exhibited sleep-enhancing activity, the underlying reason remains unclear. This study firstly revealed the structural features of potential sleep-enhancing peptides from casein hydrolysates analyzed through peptidomics and multivariate analysis. Additionally, a random forest model and a potential Tyr-based peptide library were established, and then those peptides were quantified to facilitate rapidly-screening. Our findings indicated that YP-, YI/L, and YQ-type peptides with 4-10 amino acids contributed more to higher sleep-enhancing activity of casein hydrolysates, due to their crucial structural features and abundant numbers. Furthermore, three novel strong sleep-enhancing peptides, YQKFPQY, YPFPGPIPN, and YIPIQY were screened, and their activities were validated in vivo. Molecular docking results elucidated the importance of the YP/I/L/Q- structure at the N-terminus of casein peptides in forming crucial hydrogen bond and π-alkyl interactions with His-102 and Asn-60, respectively in the GABAA receptor for activation.