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19 pages, 3016 KB

Open AccessArticle

Fermentation-Driven Generation of α-Glucosidase Inhibitory Whey Peptides by Marine-Derived Probiotic Lacticaseibacillus casei DS31: Activity Enrichment and Peptidomics

by Han Zhang, Xu Tang, Longhe Yang, Shen Yang and Peng Wu

Fermentation 2026, 12(2), 74; https://doi.org/10.3390/fermentation12020074 - 29 Jan 2026

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Abstract

This study investigated the generation of α-glucosidase inhibitory peptides from whey protein fermented by the marine-derived probiotic Lacticaseibacillus casei DS31 (isolated from the intestinal microbiota of the large yellow croaker, Larimichthys crocea) and assessed their potential for practical glycemic management. Fermentation markedly increased inhibitory activity, with the freeze-dried crude supernatant exhibiting an IC50 of 2.115 mg/mL. Activity was further enriched through stepwise purification: ultrafiltration (<3 kDa) improved potency (IC50 = 1.206 mg/mL), and subsequent Sephadex (crosslinked dextran) G-15 gel filtration yielded a more active E fraction (IC50 = 1.145 mg/mL). LC–MS/MS characterized 19 peptides, and integrated in silico screening (PeptideRanker combined with molecular docking) highlighted GEPGPEGPAG as a leading candidate, showing a more favorable predicted binding energy (−82.50 kcal/mol) than the positive control acarbose (−69.31 kcal/mol). Docking analysis suggests that GEPGPEGPAG may inhibit α-glucosidase by forming a stable network of hydrogen bonds, salt bridges, and hydrophobic interactions within the catalytic pocket. Overall, DS31-fermented whey and its enriched fractions show promise as functional ingredients for postprandial glycemic control. Full article

(This article belongs to the Section Probiotic Strains and Fermentation)

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15 pages, 3639 KB

Open AccessArticle

Thermal Behavior of Water in Sephadex^® G25 Gels at Low Temperatures Studied by Adiabatic Calorimetry

by Noriko Onoda-Yamamuro, Hiroaki Minato, Eiji Nakayama and Norio Murase

Gels 2023, 9(2), 126; https://doi.org/10.3390/gels9020126 - 2 Feb 2023

Cited by 2 | Viewed by 2341

Abstract

Water in a crosslinked dextran gel, Sephadex^® G25, is known to remain partially unfrozen during cooling and undergoes ice crystallization during rewarming. However, the mechanism of ice crystallization during rewarming is still unclear. To elucidate the frozen state of water in the gel, thermal behavior at low temperatures was investigated by using adiabatic calorimetry. Heat capacities and enthalpy-relaxation rates of the gel-containing water of mass ratio h (=g H₂O/g dry G25) = 1.00 were measured between 80 and 300 K during rewarming, where the gel was intermittently heated at the rate of 50–100 mK min⁻¹. Although an exotherm indicating ice crystallization during rewarming was confirmed with the gel precooled rapidly, at 5 K min⁻¹, it disappeared when precooled slowly, at 20 mK min⁻¹. During rewarming after the rapid cooling, two glass transitions were observed at ca. 175 K and 240–242 K. A higher-temperature glass transition due to the water trapped by the polymer network was not so clear, as it was overlapped with an endotherm due to the melting of small ice crystals, which indicates that the ice crystals formed have a broad size-distribution and that water in the gel is vitrified when ice crystals of even the smallest size cannot be formed. Full article

(This article belongs to the Special Issue Recent Advances in Crosslinked Gels)

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12 pages, 4515 KB

Open AccessArticle

Frozen State of Sephadex^® Gels of Different Crosslink Density Analyzed by X-ray Computed Tomography and X-ray Diffraction

by Norio Murase, Yuki Uetake, Yuki Sato, Kentaro Irie, Yohei Ueno, Toru Hirauchi, Toshio Kawahara and Mitsuhiro Hirai

Gels 2018, 4(2), 44; https://doi.org/10.3390/gels4020044 - 18 May 2018

Cited by 3 | Viewed by 5619

Abstract

Water in Sephadex^® (crosslinked dextran) gels is known to indicate different freezing behavior which is dependent on the density of the crosslinks, and water in a Sephadex^® G25 gel remains partially unfrozen during cooling and crystallizes during rewarming. The mechanism of anomalous ice crystallization during rewarming is still unclear. The objective of this study is to observe the ice grains that form in Sephadex^® beads and to comprehend their frozen state with a focus on the ice crystallization during rewarming. Sephadex^® beads containing 50 wt % water were prepared and used for the measurements. The observation of the ice grains was carried out by using synchrotron radiation-sourced X-ray CT (computed tomography). XRD (X-ray diffraction) analysis was also conducted to investigate the frozen state. As a result, ice grains that were larger than ~1 μm were hardly observed after the slow cooling of Sephadex^® beads, except in the G25 beads. However, at the occurrence of ice crystallization during rewarming, ice grains that were larger than 10 μm appeared in the G25 beads. Using XRD, it was found that small incomplete ice crystals were formed in G25 beads and the presence of glassy water was indicated in the gel. In conclusion, the size and distribution of ice grains that formed in Sephadex^® beads were different depending on the density of the crosslinks. Full article

(This article belongs to the Special Issue Advancements in Gel Science—A Special Issue in Memory of Toyoichi Tanaka)

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