Food-derived peptides are gaining increasing attention for their brain-beneficial potential in alleviating central nervous system diseases. Although accumulating evidence indicates neuroprotective and cognitive-enhancing properties of peptides, the precise mechanisms of action remain insufficiently understood, creating challenges for their screening, identification, and application. A major limitation is the blood–brain barrier (BBB) system, which restricts the bioavailability of peptides to the brain. In this review, current advances on food-derived peptides with brain-beneficial effects are discussed, focusing on their roles in neurotransmitter modulation, neuroprotection, anti-inflammation, anti-amyloid-β activity, and regulation of the gut–brain axis. We also discuss the peptides with brain-beneficial effects that are capable of crossing the BBB, as well as the experimental approaches used to assess their BBB permeability. Understanding both the functional actions and transport mechanisms of food-derived peptides will provide valuable insights for their application as nutraceuticals or therapeutic candidates for neurodegenerative diseases such as Alzheimer’s disease.

This study evaluated the state of water in filtered soy sauce produced using whole and defatted soybeans at different aging stages through a novel spectroscopic approach using spectra in the 4 000–100 cm^-1 region. Two indices, A_{3 210}/(A_{3 210}+A_{3 374}) and A₆₇₃/(A₆₇₃+A₄₀₃), were developed using absorbance at 3 210 and 3 374 cm^-1 and at 673 and 403 cm^-1, respectively. The A_{3 210}/(A_{3 210}+A_{3 374}) values in the middle and last stages were lower than those in the initial stage, and the A₆₇₃/(A₆₇₃+A₄₀₃) value showed a slightly increased trend among stages. These results suggest that the localized hydrogen bonding of water molecules may have been disrupted, which at a macroscopic level may have enhanced hydrogen bonding network formation due to interactions with coexisting components. The two-dimensional plot of A_{3 210}/(A_{3 210}+A_{3 374}) against A₆₇₃/(A₆₇₃+A₄₀₃) demonstrated that filtered soy sauce of different ages could be evaluated through the simultaneous analysis of the local water environment and the macroscopic water structure.

To prevent excess ingestion of salt, methods for reducing the particle size of sodium chloride (NaCl) to promote dissolution are of interest. We investigated anti-solvent crystallization and the addition of seed crystals for reducing particle size, which is typically on the order of several hundred micrometers. Anti-solvent crystallization is suitable for producing crystals measuring <50 µm in size. Therefore, we used a Taylor–Couette (TC) crystallizer that generates small crystals with a uniform particle size to produce seed crystals. The seed crystal slurry was suspended in an anti-solvent. We conducted two experiments by adding the anti-solvent to an NaCl aqueous solution and by adding an NaCl aqueous solution to the anti-solvent. As a result, cubic NaCl crystalline particles with a smooth surface and an average particle size (D₅₀) of 66.5 µm were successfully obtained using a seed crystal slurry prepared via the TC vortex.

Blackcurrant (Ribes nigrum) fruit has been traditionally eaten in Europe and elsewhere. The polysaccharides in blackcurrant reportedly have anti-allergic and immunostimulatory effects and other functional properties, but their structure has not yet been resolved. This study investigated the immunostimulatory effects of blackcurrant polysaccharides, with the aim of identifying their active structures. Polysaccharides isolated from blackcurrant significantly up-regulated inducible nitric oxide synthase (iNOS) and interleukin (IL)-6 expression in RAW264.7 cells. Further analyses of the active fraction (Fr.) 3 revealed that it increased IL-6, tumor necrosis factor-α (TNF-α), and nitric oxide (NO) production in a dose dependent manner. The sugar composition of Fr. 3 indicated the presence of rhamnogalacturonan-I (RG-I) and xylogalacturonan (XGA), with approximate molecular weights of 5,000 Da. These findings suggest that the blackcurrant polysaccharide immunostimulatory activity is linked to this unique RG-I and XGA structure, highlighting their potential as functional food ingredients.

This study investigated the effects of seven-day oral supplementation with menthol crystals on thermoregulatory responses in young Japanese women following cold-water hand immersion. Peripheral skin temperature, blood flow, and subjective thermal sensation were assessed. Menthol ingestion did not affect the recovery of skin temperature or blood flow at the fingers and wrists. However, skin temperature at the toes was significantly higher in the menthol group during cold exposure, indicating an enhanced peripheral thermal response in the distal regions. Subjective thermal sensation at the feet was also significantly higher in the menthol group than in the control group. These findings suggest that short-term menthol supplementation may have region-specific effects, helping to maintain warmth perception in the extremities. Although the underlying mechanisms remain to be clarified, menthol ingestion could potentially alleviate cold sensitivity in susceptible individuals.

In this study, we investigated the effects of shio-koji treatment on beef tenderization and proteolysis under varying conditions of temperature, pH, and NaCl concentration. Bovine protein hydrolysis was maximized at 40–50 ^oC and pH 5.0 with shio-koji treatment. The addition of 3 % (w/v) or more NaCl slightly reduced the degree of hydrolysis. SDS-PAGE analysis and phase-contrast microscopy revealed that bovine myofibrils were partially hydrolyzed. Although bovine myofibrils were hydrolyzed at 4 °C, the degree of degradation was limited. Immersion in shio-koji solution tenderized beef and reduced its breaking stress. On the other hand, beef samples subjected to treatment with heat-inactivated shio-koji also exhibited a marginal decrease in breaking stress compared to the untreated control group. These results suggest that, in addition to proteases, shio-koji contains non-enzymatic meat tenderizing factors, such as acids and salts, which may contribute to optimal beef tenderization.