Mushroom-Mediated Reductive Bioconversion of Aldehyde-Rich Essential Oils for Aroma Alteration: A Rose-like Floral Bioflavor from Citronella Oil

Ultrasound triggered process optimization of Etlingera linguiformis (Roxb.) R.M.Sm. nanoemulsion: Its stability, cytotoxicity and antibacterial activity

Periodontal infections and dental caries are leading causes of tooth loss, impacting overall health and quality of life. Conventional treatments involve antibiotics, antiamoebic drugs, and quaternary ammonium compounds, their prolonged use can cause resistance and toxicity. In this study, E. linguiformis essential oil (ELEO) was evaluated for chemical composition, and its nanoemulsion (ELEON) with good stability was characterized for ELEON properties, prepared using ultrasonication, and assessed for their antibacterial efficacy. The results showed that ELEO is dominated by estragole as the major compound, with the 60-minute sonicated sample exhibiting the best stability and uniform droplet size (220.03 d.nm) distribution. Prolonged ultrasonication led to an increase in particle size, highlighting the importance of optimal processing. Antibacterial analysis revealed that ELEON exhibited higher activity than ELEO against S. mutans and S. aureus, attributed to its smaller droplet size and enhanced penetration into microbial cells. Transmission Electron Microscope (TEM) showed the droplet diameter comparable to the particle size measured in Dynamic light scattering (DLS). Scanning Electron Microscopy (SEM) revealed significant morphological changes and membrane disruption in bacteria treated with ELEO and ELEON, leading to cell death. The cytotoxicity of ELEO and ELEON from E. linguiformis rhizomes was evaluated on L929 fibroblast cell lines using the MTT assay, showing no significant reduction in cell viability across tested concentrations. ELEON enhances essential oil stability and antimicrobial efficacy, demonstrating thepotential for pharmaceutical applications and antibiotic resistance management.

Mushroom mediated selective bioreduction of S-(+)-carvone to cis-(-)-dihydrocarvone: approach towards a safer biocatalysis

Dihydrocarvone, possessing four stereoisomers is an important flavour and chiral building block in chemical synthesis. Ascomycetes are well known for the selective bioreduction of carvone to dihydrocarvone. Often, these fungi produce mycotoxins which may contaminate the biocatalytic product. Herein, Ganoderma sessile, a polypore mushroom, selectively reduced S-(+)-carvone to cis-(-)-dihydrocarvone (DHC) in its submerged culture. In an optimised condition (0.75 g/L, 18 h, pH 3-5, 30 °C and 150 rpm), 82.7% cis-(-)-DHC was obtained in gas chromatography-mass spectrometry profile of the fermented product. The absolute titre of cis-(-)-DHC in fermentation medium was 0.35 ± 0.01 g/L. However, substrate toxicity (IC50 0.15 g/L) drastically reduced the transformation at higher carvone concentration (≥1.0 g/L). On the other hand, R-(-)-carvone was less selective and efficient in producing the desired isomer i.e. trans-(+)-DHC. G. sessile is the member of a group of non-toxic medicinal mushrooms and may be a safer yet efficient option for producing cis-(-)-DHC biocatalytically.

A high performance thin layer chromatography (HPTLC) method for the quality assessment of citronella oil: application in commercial sample analysis

Citronella oil, extracted from Cymbopogon species (winterianus and nardus) is a commercially valuable essential oil used in personal-care products and insect repellents. Routine analysis in gas chromatography is incapable of detecting high-boiling adulterants therein. In this study, an HPTLC technique was developed for the absolute quantification of citronellal (characteristic chemical marker) and triglyceride (main constituent of vegetable oil adulterant) in citronella oil for its quality assessment. It was validated in terms of specificity, linearity, sensitivity, accuracy and precision. Further, the developed method was employed to quantify citronellal and triglyceride in twenty commercial samples. The results showed a wide variation in citronellal content (trace to 30.65% w/w) and could differentiate its two chemotypes. Also, it revealed the possibility of vegetable oil adulteration through the detection and quantification of triglyceride in selected samples. It can be a simple and rapid technique for the quality control of citronella oil.

Evaluation of the phytochemical, bioactive compounds and descriptive sensory of encapsulated lingzhi (Ganoderma lucidum) extracts with combined wall materials for masking effect on the perception of off-flavour and bitterness

Lingzhi mushroom (Ganoderma lucidum) is known as a medicinal mushroom that can be utilized in various functional foods available in the market, including powders, dietary supplements, and tea. However, its use is limited due to factors such as bitterness, flavour, and astringency. The objective of this study is to characterize and quantify the sensory profile of Lingzhi mushroom samples (fresh, dried and Lingzhi extracts) using quantitative descriptive analysis and investigate the physicochemical and sensory properties of encapsulated Lingzhi extracts using different ratios of wall material (maltodextrin, gum Arabic and modified starch from rice flour). The optimal ratio for encapsulation involved 32.75 % maltodextrin, 42.25 % gum Arabic, and 25 % modified starch w/w. Three parallel experiments were performed under practical conditions, resulting in average encapsulation efficiencies of 88.39 ± 0.09 % for flavonoids 89.53 ± 0.06 % for polysaccharides and 0.31 ± 0.01 of water activity. The sensory descriptive analysis indicated the following ratings: brown sugar aroma (4.36 ± 0.17), earthy aroma (22.04 ± 0.12), nutty aroma (2.00 ± 0.01), fresh mushroom aroma (11.18 ± 0.19), dried Lingzhi aroma (3.08 ± 0.13), black tea aroma (4.50 ± 0.19), salty taste (1.00 ± 0.01), earthy flavour (23.14 ± 0.22) and Mushroomy (after taste) (2.06 ± 0.09), respectively. The flavour identified of Lingzhi extracts and encapsulated by gas chromatography electronic nose (GC-E-Nose). The result showed ten flavour compounds (Acetaldehyde, Methanethiol, Propanal, propane-2-one, Methyl acetate, 2-methyl propanal, Ethyl Acetate, Heptane, 1-Butanamine, 2-methyl butanal, Thiophene). Optimizing the encapsulation conditions has a significant impact on reducing off-flavours and bitterness. Comparing the flavour profiles of Lingzhi extracts with encapsulated Lingzhi extracts using gas chromatography electronic nose (GC-E-Nose). Encapsulation technology represents a burgeoning field that holds immense potential in ensuring the stability of functional ingredients and facilitating their incorporation into instant beverage products.

Peroxyl Radical Trapping Antioxidant Activity of Essential Oils and Their Phenolic Components

Essential oils (EOs) are gaining importance as sustainable food antioxidants, but kinetic data on peroxyl radical trapping are missing. Thirteen EOs from 11 botanical species were studied in the inhibited autoxidation of cumene by oxygen-uptake kinetics. EOs of Juniperus oxycedrus, Syzygium aromaticum, Thymus vulgaris, Thymbra capitata, Betula alba, Pimenta racemosa, and Satureja montana, containing 23-86% phenolic components by gas chromatography/mass spectrometry (GC-MS) analysis, afforded inhibition rate constants kinh in the order of 104 M-1 s-1 at 30 °C similar to reference butylhydroxytoluene (2,6-di-tert-butyl-4-methylphenol) (BHT). They matched or outperformed BHT in the protection of olive oil. The EOs Daucus carota and Cedrus atlantica with <1% phenols and those of Apium graveolens and Tagetes minuta with no phenolics had no chain-breaking activity. Key components carvacrol, thymol, eugenol, dihydroeugenol, umbelliferone, conyferyl alcohol, o-cresol, m-cresol, p-cresol, 4-allylphenol, 2,3-xylenol, 2,4-xylenol, and phenol had kinh in the range of 103-104 M-1 s-1 and, along with EOs containing them, could potentially replace BHT in the protection of food products.

Applications of Ene-Reductases in the Synthesis of Flavors and Fragrances

Flavors and fragrances (F&F) are interesting organic compounds in chemistry. These compounds are widely used in the food, cosmetic, and medical industries. Enzymatic synthesis exhibits several advantages over natural extraction and chemical preparation, including a high yield, stable quality, mildness, and environmental friendliness. To date, many oxidoreductases and hydrolases have been used to biosynthesize F&F. Ene-reductases (ERs) are a class of biocatalysts that can catalyze the asymmetric reduction of α,β-unsaturated compounds and offer superior specificity and selectivity; therefore, ERs have been increasingly considered an ideal alternative to their chemical counterparts. This review summarizes the research progress on the use of ERs in F&F synthesis over the past 20 years, including the achievements of various scholars, the differences and similarities among the findings, and the discussions of future research trends related to ERs. We hope this review can inspire researchers to promote the development of biotechnology in the F&F industry.

Structure-Based Redesign of a Methanol Oxidase into an "Aryl Alcohol Oxidase" for Enzymatic Synthesis of Aromatic Flavor Compounds

Alcohol oxidases (AOxs) catalyze the aerobic oxidation of alcohols to the corresponding carbonyl products (aldehydes or ketones), producing only H₂O₂ as the byproduct. The majority of known AOxs, however, have a strong preference for small, primary alcohols, limiting their broad applicability, e.g., in the food industry. To broaden the product scope of AOxs, we performed structure-guided enzyme engineering of a methanol oxidase from Phanerochaete chrysosporium (PcAOx). The substrate preference was extended from methanol to a broad range of benzylic alcohols by modifying the substrate binding pocket. A mutant (PcAOx-EFMH) with four substitutions exhibited improved catalytic activity toward benzyl alcohols with increased conversion and k_cat toward the benzyl alcohol from 11.3 to 88.9% and from 0.5 to 2.6 s^-1, respectively. The molecular basis for the change of substrate selectivity was analyzed by molecular simulation.