Journal of Food Bioactives

Matcha (Japanese ground green tea) and cognitive function

Klaus W. Lange, Yukiko Nakamura — Wed, 30 Sep 2026 00:00:00 +0800

Matcha is a finely ground powder made from shade-grown green tea leaves. It is primarily produced in Japan. Drinking matcha tea results in higher intake of green tea bioactives than drinking other types of green tea. Studies have found that matcha consumption may enhance cognitive function in situations with and without psychological stress, in the short and long term, and in different age groups. The effects of matcha on cognitive function may be due to stress reduction, improved sleep quality, an increased supply of vitamin K, altered intestinal microbiota composition, decreased oxidative stress, enhanced cholinergic brain function, and increased cortical capillary network angiogenesis. Matcha’s stress-reducing efficiency appears to be influenced by differences in the quantities and ratios of its components, which may affect cognitive function. Matcha must contain high levels of theanine to have beneficial effects on stress and anxiety. Furthermore, the ratio of epigallocatechin gallate and caffeine to theanine and arginine must be low. Since not all marketed matcha products worldwide meet these conditions, quality control is important. Harnessing matcha’s beneficial properties may effectively support cognitive function and prevent cognitive decline and dementia.

Microbial biotransformation of plant-derived bioactive compounds: structural modifications, enhanced bioavailability, and functional food applications

Ying Ni, Wensheng Zhang, Yao Sun, Zhengyong Yu, Youhua Xu — Wed, 30 Sep 2026 00:00:00 +0800

Plant-derived bioactive compounds, including polyphenols, polysaccharides, alkaloids, terpenoids/saponins, lignans and glucosinolates, are widely valued for their health-promoting potential, yet poor bioavailability and, in several cases, biological inactivity in native form limit their translation into functional food ingredients. Microbial biotransformation, carried out by naturally occurring gut microbiota, food-fermentation microorganisms and plant-associated endophytic fungi, offers a means of overcoming these limitations through mild, highly selective enzymatic modification. This review synthesizes current evidence on microbial biotransformation across five major classes of plant bioactive compounds, examining the natural microbial sources involved, the core enzymatic mechanisms, including glycosidases, esterases, oxidoreductases, decarboxylases and demethylases, responsible for these conversions, and the resulting changes in bioavailability and bioactivity for each compound class. Beyond the compound-specific discussion, we identify a smaller set of structural modifications, namely deglycosylation, molecular weight reduction, hydroxylation, demethylation, ring cleavage and decarboxylation, that recur across otherwise unrelated compound classes and account for much of the functional benefit associated with microbial processing. We discuss current applications in fermented functional foods and postbiotics, together with the principal obstacles, including strain stability, substrate specificity in complex matrices, and regulatory characterization, that constrain industrial-scale deployment, and outline multi-omics-guided and precision-fermentation strategies likely to shape future progress in this field.

Coreopsis tinctoria and its bioactives in the prevention and management of diabetes and diabetic complications

Wenyu Zhang, Yixing Zhu, Junfeng Shen, Alexander Gosslau — Wed, 30 Sep 2026 00:00:00 +0800

Diabetes, one of the major metabolic diseases, has become a major public health concern worldwide leading to chronic lesions in various organs such as kidney and cardiovascular disease, severely impacting quality of life and life expectancy. Current drug treatments for diabetes have varying degrees of side effects. Therefore, finding natural, safe, and effective functional foods to prevent and control diabetes and its complications has become a research hotspot. Coreopsis tinctoria Nutt. (C. tinctoria) is rich in polyphenols (e.g. flavonoids), polysaccharides, and other bioactive components, possessing various health benefits. Studies have shown that C. tinctoria flavonoids lower blood sugar levels through multiple pathways, including suppressing oxidative stress, decreasing the inflammatory cascade, regulating glucose and lipid metabolism, increasing insulin sensitivity and improving insulin resistance. This review briefly summarizes the research progress on diabetes and its complications, and details the mechanisms of action of C. tinctoria bioactives in prevention and treatment of diabetes and its complications. The aim is to provide the molecular mechanisms of C. tinctoria and its bioactives for a potential application of C. tinctoria in controlling diabetes and its complications.

In vitro bile acid-binding ability of black soybean seed coat

Naho Mizuno-Nagata, Hitoshi Ashida, Toshiya Toda — Wed, 30 Sep 2026 00:00:00 +0800

Bile acid-binding ability with dietary components is known to modulate cholesterol metabolism. However, the bile acid-binding potential of polyphenols in black soybean (Glycine max L.) seed coat has not yet been fully elucidated. In this study, we quantified the bile acid-binding ability of both black and yellow soybean seed coats and their polyphenols. Suspended seed coat revealed the ability to bind cholic and deoxycholic acids: the binding ability of black soybean seed coat significantly exceeded that of yellow one. This ability was observed in both water-soluble and water-insoluble fractions from black soybean seed coat. The ability of the water-soluble fraction is attributed to anthocyanins and low-molecular-weight proanthocyanidins, whereas that of the water-insoluble fraction is mainly due to highly polymerized proanthocyanidins. These findings suggest that the intake of black soybean seed coat may maintain healthy cholesterol homeostasis through the excretion of bile acids.

Pyroglutamyl peptide–rich rice protein hydrolysate restores cecal N-acetyl amino acids in high-fat-diet–fed rats, outperforming short-chain fatty acids as early microbial markers

Wed, 30 Sep 2026 00:00:00 +0800

Pyroglutamyl-leucine (pyroGlu-Leu) is a food-derived modified peptide known to modulate the gut microbiota. This study examined the effects of orally administered rice protein hydrolysate (RPH) containing pyroGlu-Leu in rats fed a 45% high-fat diet that induced mild dysbiosis without obesity or severe liver dysfunction. In addition to short-chain fatty acids (SCFAs), several N-acetyl amino acids (NAAAs) were detected in cecal contents. The high-fat diet significantly decreased both SCFAs and NAAAs, whereas administration of RPH or synthetic pyroGlu-Leu restored the levels of NAAAs despite not recovering those of SCFAs. RPH did not alter the overall gut microbial composition but modified specific bacterial taxa that correlated with NAAA levels. These results suggest that NAAAs are gut microbiota-derived metabolites that respond more sensitively to food-derived modulation of the gut microbiota than SCFAs, and may serve as early indicators of microbiota–host metabolic interactions.

Probiotics characterization of fermented tiger nut-millet-blended beverage

Wed, 30 Sep 2026 00:00:00 +0800

This study investigated the functional characteristics and probiotic potential of lactic acid bacteria (LAB) isolated from a fermented tiger nut-millet beverage. The beverage was prepared using a traditional tiger nut fermentation process (sorting, cleaning, soaking, spicing, wet-grinding, fermentation, filtration, chilling, and storage), and samples were collected at 6-hour intervals throughout the 48-hour fermentation time for microbiological analysis. The isolated LAB were evaluated for probiotic properties, including tolerance to acidic pH, bile salts, and phenol. Their antibiotic susceptibility and antibacterial activities against selected pathogenic bacteria were also assessed. LAB counts increased from 2.30 to 6.40 log₁₀ CFU/mL during fermentation. The isolates were identified using the API 50 CHL system and 16S rRNA gene sequencing, revealing members of the genera Leuconostoc and Lactiplantibacillus. Selected isolates exhibited strong tolerance to simulated gastrointestinal conditions, with survival rates exceeding 50% at acidic pH (2.0–3.0), bile salt concentrations (0.3% and 2%), and phenol concentrations (0.2% and 0.3%). The isolates also demonstrated susceptibility to clinically relevant antibiotics and exhibited antibacterial activity against selected foodborne pathogens, producing inhibition zones ranging from 11.0 to 20.0 mm. These findings demonstrate the probiotic potential of LAB and their suitability for developing non-dairy functional foods and nutraceutical products.

Effects of tamarind seed husk extract on abdominal visceral fat: a randomized, double-blind, placebo-controlled trial in Japanese adults with mild obesity

Wed, 30 Sep 2026 00:00:00 +0800

Tamarind seed husk, a by-product of gum production, is rich in polyphenols. We examined whether tamarind seed husk extract (TSHE) reduces abdominal visceral fat area (AVFA) in Japanese adults with mild obesity. In a randomized, double-blind, placebo-controlled trial (UMIN000057223), 112 adults (25 ≤ BMI < 30 kg/m²) received TSHE (200 mg/day) or placebo for 12 weeks. AVFA at week 12, the primary outcome, was lower but not significantly (p = 0.077). AVFA was already significantly lower at week 4, and the percent reduction in total fat area was significant at weeks 8 and 12. Reductions were greater in participants with a baseline visceral-to-subcutaneous fat ratio ≥ 0.4. No adverse events occurred, indicating that TSHE is safe as a food ingredient. This is the first clinical trial to show that TSHE (200 mg/day) reduces visceral fat in mildly obese adults with a visceral-to-subcutaneous fat ratio ≥ 0.4.

Effects of egg white hydrolysate on facial swelling: a randomized, double-blind, placebo-controlled, crossover trial

Wed, 30 Sep 2026 00:00:00 +0800

This study evaluated whether egg white hydrolysate (EWH) reduces morning facial swelling in healthy adults who routinely experience this condition (UMIN000057170). Seventy-six participants were randomly assigned to an EWH-first or placebo-first sequence in a double-blind, placebo-controlled, crossover trial. Participants ingested 250 mg of EWH or placebo once daily before bedtime for one week, separated by a 2-week washout. The primary outcome was the morning Visual Analogue Scale (VAS) score for facial swelling after 1-week intervention. Secondary outcomes included other subjective swelling and coldness sensations, and calf and ankle circumferences. A total of 61 participants were included in the final analysis. EWH intake significantly reduced the VAS score for morning facial swelling compared with placebo after one week (VAS: 54.8 ± 2.6 vs. 58.8 ± 2.6; P = 0.037). Therefore, EWH has the potential to serve as a functional food ingredient that reduces transient facial swelling and improves quality of life in healthy adults.