Institute of Food Science and Technology

The honeys produced by Apis mellifera ligustica Spinola (A. mellifera) and Apis cerana cerana Fabricius (A. cerana) are the two predominant varieties in terms of global yield, each recognized for its distinct functional properties. Our previous studies identified the characteristic markers distinguishing A. cerana honey and A. mellifera honey. However, the mechanistic links between species-specific metabolism and functional properties remain unclear, presenting a formidable challenge. This study aimed to elucidate how bee species-specific metabolism shapes honey bioactivity. We used topological and enrichment analyses to map the characteristic markers onto metabolic pathways. Also, we quantified the in vitro antioxidant capacity of both honeys and their respective markers via 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging assays. We further evaluated the anti-inflammatory efficiency of these honeys in lipopolysaccharide-stimulated Caco-2 cells by measuring cytokine expression and cellular responses. Tryptophan metabolism primarily contributed to the formation of honey in both A. cerana and A. mellifera. A. cerana preferentially metabolized tryptophan via the indoleacetic acid pathway, yielding higher concentrations of methyl indole-3-acetate (MIA), whereas A. mellifera favored the kynurenine pathway, producing elevated levels of kynurenic acid (KYNA). Both compounds enhanced intestinal barrier integrity through their antioxidant and anti-inflammatory activities, despite differing in their specific mechanisms and efficacy. MIA exhibited superior anti-inflammatory and antioxidant properties compared with KYNA, which directly correlated with the enhanced bioactivity of A. cerana honey. KYNA primarily strengthened barrier function by upregulating the expression of tight junction proteins Zonula occludens protein-1(ZO-1), claudin-1, and occludin, whereas MIA demonstrated greater efficacy in suppressing the expression of inflammatory proteins. Correlation analyses confirmed MIA and KYNA as the key drivers of the intestinal barrier-protective activities of honey. The complementary mode of action-KYNA providing structural reinforcement and MIA offering anti-inflammatory modulation-highlights the synergistic bioactivity underlying the protective properties of honey. These findings provide a mechanistic understanding of how bee species-specific tryptophan metabolism in A. cerana and A. mellifera drives the bioactivity divergence in honey, with MIA and KYNA linked to differential antioxidant and intestinal anti-inflammatory activities.

Whole grains, due to their intact structure, retain more nutrients and offer significant health benefits. Thermal modification is commonly applied to modify cereal grains. This study aimed to investigate the effects of thermal treatments (microwaving (abbreviation MW-BW), roasting (RST-BW), and an emerging technology, heat fluidization (HFL-BW)) on whole-grain black wheat flour. The results showed minimal loss in proximate composition and increased anthocyanin content (from 38.78 mg/kg (BW) to 39.57 (HFL-BW) and 46.06 mg/kg (MW-BW)) relative to the control. Analysis of physical properties and microstructure revealed that all thermal treatments caused kernel swelling, darkened the flour color, decreased the kernel hardness, and disrupted the starch microstructure. All thermal treatments disrupted starch short-range order and reduced crystallinity (from 26.75% (BW) to 2.56 (HFL-BW) and 15.74% (RST-BW)), resulting in a transformation to a V-type structure. The protein secondary structure (mainly for α-helix) was disrupted, and gluten was denatured and aggregated in all thermal-treatment groups. Thermal treatments decreased gelatinization enthalpy (from 4.76 J/g (BW) to 0.59 (HFL-BW) and 4.44 J/g (RST-BW)) and altered pasting viscosity. The viscoelasticity of pastes made from thermal treatments was improved. In vitro digestibility results showed that thermal treatments decreased starch digestibility, decreased the protein bioavailability, and increased resistant starch content (from 20.1% (BW) to 30.9 (MW-BW) and 39.6% (RST-BW)). Altogether, heat fluidization had the most pronounced effect among the treatments. Thermal modifications-particularly heat fluidization-are promising technologies for enhancing the quality of whole-grain black wheat flour and developing functional foods.