Ming Yi Lee

Lemon processing by-products are rich in flavonoids, limonoids, and phenolic acids, but their direct utilization is limited by glycoside-dominant flavonoid profiles, bitterness-associated limonoids, and insufficiently defined valorization strategies. This study compared eight food-relevant microorganisms, including lactic acid bacteria, Bacillus, yeast, and filamentous fungi, using a common aerobic submerged fermentation framework for lemon by-products. Rather than evaluating fermentation as a single uniform process, the study aimed to determine whether different microbial groups could redirect the same substrate toward distinct functional remodeling profiles. Targeted HPLC analysis of flavonoids, limonoids, and phenolic acids, together with DPPH and ABTS radical-scavenging assays, revealed clear strain-dependent differences in metabolite remodeling and antioxidant outcomes. L. plantarum showed the most consistent antioxidant enhancement profile, characterized by increased hesperetin and phenolic acid responses together with low DPPH and ABTS IC₅₀ values. L. pentosus promoted flavonoid remodeling but showed a more timing-sensitive antioxidant response. S. cerevisiae tended to preserve glycosylated flavonoids and showed a release-oriented phenolic acid profile with strong early ABTS activity. R. stolonifer exhibited the most pronounced limonoid remodeling, including marked limonin reduction and obacunone accumulation, suggesting potential relevance for bitterness-oriented applications. These findings demonstrate that different microorganisms can be functionally classified according to their dominant remodeling tendencies, including antioxidant enhancement, flavonoid conversion, glycosylated flavonoid preservation, phenolic acid release, and limonoid-associated debittering. This functional classification provides a practical basis for selecting microorganisms according to the intended application of lemon by-product valorization.

Kinmen peanut (Arachis hypogaea L. cultivar Kinmen No. 1) is a unique crop used to produce local specialty “peanut candy”; however, the peanut skins (PSs) are treated as waste owing to the bitter taste. To support the valorization of this agro-industrial by-product, peanut skin ethanolic extract (PSE) was prepared and evaluated for its hypolipidemic potential in a cholesterol/fat-fed hamster model, together with its antioxidant capacity and chemical composition. Hamsters were fed a cholesterol/fat-enriched diet supplemented with PSE at 0.1%, 0.2%, or 0.4% (w/w) for 8 weeks. Serum lipid profiles were determined, and derived atherogenic indices were calculated. In parallel, antioxidant activity was assessed using 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2′-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), and reducing power assays, while chemical characterization included total phenolics, crude phytosterols, and HPLC profiling of representative phenolic compounds. PSE significantly reduced serum total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) compared with the cholesterol/fat-enriched control, whereas triglycerides were not significantly altered. The LDL-C/HDL-C ratio was also reduced in PSE-treated groups, with the greatest reduction observed in the 0.1% PSE group (0.33 ± 0.04 vs. 0.56 ± 0.12 in the negative control). In addition, PSE exhibited marked antioxidant activity, with IC₅₀ values of 141.3 and 76.2 μg/mL in the DPPH and ABTS assays, respectively. Chemical analyses showed that PS contained 1098 ± 189 µg β-sitosterol equivalents/g PS and 199.3 ± 4.6 mg gallic acid equivalent (GAE)/g PS, and HPLC identified p-coumaric acid, ferulic acid, gallic acid, chlorogenic acid, daidzein, catechin, and resveratrol as representative phenolic constituents. Collectively, these findings support Kinmen peanut skin as a promising value-added source of bioactives for functional ingredient development targeting cholesterol dysregulation and oxidative processes.

Lemon by-products are rich in water-soluble pectin containing galacturonic acid (GalA), which exhibits limited antioxidant activity but may mask phenolic- and flavonoid-related antioxidant contributions. However, the extent of GalA interference during fermentation has not been quantitatively clarified. In this study, correlation analysis and multivariate statistical modeling were applied to fermented lemon by-products to evaluate the influence of GalA on antioxidant measurements. GalA showed the highest temporal variability and dominated loading structures in both PCA and PLS-DA models. ABTS IC₅₀ was negatively correlated with total phenolic content, while the association between DPPH and total flavonoid content became significant only after GalA adjustment (r = 0.258, p = 0.043). Statistical correction enhanced antioxidant–phenolic/flavonoid correlations by nearly threefold and shifted multivariate patterns toward antioxidant-related variables. These results provide quantitative evidence of GalA-induced matrix interference. A two-step extraction strategy is proposed to improve antioxidant evaluation accuracy in pectin-rich citrus by-products.

Jelly fig is a crop of high economic value; however, the processing by-product of jelly fig, “jelly fig shell”, is not well utilized. In this study, jelly fig shell pectin was extracted through the microwave extraction technique. Then, galacturonic acid content, degree of esterification, molecular weight, functional group properties, and antioxidant activity were determined. The highest pectin yield (21.6 ± 0.1 %) was obtained at 200 mM citric acid and microwave power of 800 W, with extraction time of 4 min. The content of galacturonic acid in pectin was greater than 65 %, which meets the specifications of food-grade pectin. In terms of antioxidant ability, the IC50 of 2,2-diphenylpicrylhydrazyl (DPPH) free radical scavenging rate of jelly fig shell pectin was 175.1 μg/mL. These results suggest that, comparing to the extracted jelly fig seed pectin, jelly fig shell has stable quality under more desirable extraction conditions, and has better physicochemical properties.

This study aimed to evaluate the antiglycation effects of adlay on protein glycation using in vitro glycation assays. Adlay seed was divided into the following four parts: the hull (AH), testa (AT), bran (AB), and polished adlay (PA). A solvent extraction technique and column chromatography were utilized to investigate the active fractions and components of adlay. Based on a BSA-glucose assay, the ethanolic extracts of AT (ATE) and AB (ABE) revealed a greater capacity to inhibit protein glycation. ATE was further consecutively partitioned into four solvent fractions with n-hexane, ethyl acetate (ATE-Ea), 1-butanol (ATE-BuOH), and water. ATE-BuOH and -Ea show marked inhibition of glucose-mediated glycation. Medium–high polarity subfractions eluted from ATE-BuOH below 50% methanol with Diaion HP-20, ATE-BuOH-c to -f, exhibited superior antiglycation activity, with a maximum inhibitory percentage of 88%. Two phenolic compounds, chlorogenic acid and ferulic acid, identified in ATE-BuOH with HPLC, exhibited potent inhibition of the individual stage of protein glycation and its subsequent crosslinking, as evaluated by the BSA-glucose assay, BS-methylglyoxal (MGO) assay, and G.K. peptide-ribose assay. In conclusion, this study demonstrated the antiglycation properties of ATE in vitro that suggest a beneficial effect in targeting hyperglycemia-mediated protein modification.