Simple sequence repeats (SSR) markers and secondary metabolite composition were used in combination to study seven varieties of citrus for the first time. With reference to established accessions of ...citrus, two of the varieties (Chanh Giay and Ma Nao Pan) were predicted to be Mexican key limes, while three were mandarin hybrids (Nagpur, Pontianak and Dalandan) and the remaining two (Qicheng and Mosambi) were related to the sweet orange. Notably, Dalandan was genetically more like a mandarin despite often referred to as an orange locally, whereas Mosambi was more likely to be a sweet orange hybrid although it has also been called a sweet lime due to its green peel and small size. Several key secondary metabolites such as polymethoxyflavones (sinensetin, tangeretin etc.), furanocoumarins (bergapten, citropten etc.) and volatiles (citronellol, α-sinensal etc.) were identified to be potential biomarkers for separation of citrus species. However, despite having similar genetic profiles, variations in the volatile profile of the two limes were observed; similarly, there were differences in the secondary metabolite profiles of the three mandarin hybrids despite having a common ancestral parent, highlighting the usefulness of genetic and compositional analyses in combination for revealing both origins and flavour profiles especially in citrus hybrids. This knowledge would be crucial for variety screening and selection for use in flavour or fragrance creation and application.
UPLC-Q-TOF-MS was employed to analyse the non-volatile components of green teas fermented with probiotic yeast (Saccharomyces boulardii) and lactic acid bacteria (LAB, Lactiplantibacillus plantarum). ...The flavone glycosides in yeast-fermented and stored tea decreased significantly, together with the increases of flavone aglycones and other simple flavone glycosides. LAB-fermented tea presented different flavone glycoside profiles; in which, both C-glycosides and O-glycosides decreased and the flavone aglycones were further degraded. The profiles of flavone glycosides and aglycones in co-cultured tea differed from that in yeast- or LAB-fermented tea; less glycosides were degraded but a greater number of aglycones were produced. Two unique LAB metabolites with bioactive and antifungal properties, D-phenyllactic acid (PLA) and p-OH-PLA, were found in both L. plantarum and co-cultured teas, and the co-fermentation showed a synergic effect on the production of these two compounds that would enhance the quality and preservation of fermented teas.
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•UPLC-QTOF-MS was used to analyse non-volatile components of probiotics-fermented green teas.•Changes of flavone glycosides and aglycones in monocultures and co-culture differed.•D-phenyllactic acid (PLA) and p-OH-PLA were found in both L. plantarum and co-cultured teas.•Co-fermentation showed a synergic effect on the production of PLA and p-OH-PLA.
At present, the identification of honeysuckle aroma depends on experienced tasters, which results in inconsistencies due to human error. The key odorants have the potential to distinguish the ...different species and evaluate the quality of honeysuckle. Hence, in this study, a more scientific approach was applied to distinguish various honeysuckles. The volatile compounds of different species and parts of honeysuckle were separately extracted by headspace-solid phase microextraction (HS-SPME) and solvent assisted flavor evaporation (SAFE). Compounds with greater volatility such as aldehydes, limonene, gamma-terpinene, and terpinolene were preferentially extracted by HS-SPME. As a complementary extraction method to HS-SPME, SAFE was found to recover comparatively more polar compounds such as eugenol, decanoic acid, and vanillin. Subsequently, key odorants with the highest flavour dilution (FD) factors were detected by aroma extract dilution analysis (AEDA). These were benzaldehyde, 4-ethylphenol, decanoic acid, vanillin, 3-methyl-2-butenal, and beta-ionone in honeysuckle flowers and gamma-octalactone, 4-ethyl phenol, and vanillin in honeysuckle stem. Finally, principal component analysis (PCA) was conducted to analyze not only the key odorants of species and parts of honeysuckle but also their different origins. The results of PCA suggested that the species of honeysuckle contributed much more to variations in aroma rather than their origins. In conclusion, the application of the key odorants combined with PCA was demonstrated as a valid approach to differentiate species, origins, and parts of honeysuckle.
Consumer interest and research in plant-based dairy analogues has been growing in recent years because of increasingly negative implications of animal-derived products on human health, animal ...wellbeing, and the environment. However, plant-based dairy analogues face many challenges in mimicking the organoleptic properties of dairy products due to their undesirable off-flavours and textures. This article thus reviews fermentation as a viable pathway to developing clean-label plant-based dairy analogues with satisfactory consumer acceptability. Discussions on complementary strategies such as raw material selection and extraction technologies are also included. An overview of plant raw materials with the potential to be applied in dairy analogues is first discussed, followed by a review of the processing steps and innovative techniques required to transform these plant raw materials into functional ingredients such as plant-based aqueous extracts or flours for subsequent fermentation. Finally, the various fermentation (bacterial, yeast, and fungal) methodologies applied for the improvement of texture and other sensory qualities of plant-based dairy analogues are covered. Concerted research efforts would be required in the future to tailor and optimise the presented wide diversity of options to produce plant-based fermented dairy analogues that are both delicious and nutritionally adequate.
The separation of isomers is one of the key issues in analysing complex natural matrices, thus commanding a higher separating power from the applied analytical system. In this study, 42 common ...flavonoid glycosides from three key subclasses (flavanones, flavones, flavonols) were analysed in three steps to maximise chromatographic and spectrometric resolution via: (1) C18 liquid chromatography (LC) coupled to a quadrupole time-of-flight mass spectrometer (QTOF/MS), (2) tandem mass spectrometry (MS/MS), and (3) two-dimensional LC with heart-cutting for specific regions of co-elution. While the LC-QTOF/MS step was found to separate the majority of flavonoid glycoside isomers, some isomers with identical accurate mass were not resolved. Following this, increased spectrometric resolution was achieved with MS/MS; however, this technique was not suitable for particularly challenging isomers that were also identical in aglycone and saccharide structure. Furthermore, a heart-cutting method was developed using a three-level full-factorial design to separate such challenging isomers, and satisfactory resolution was obtained for the targeted isomers (
R
> 2.00) with reasonable efficiency (total run time < 25 min) and repeatability (RSD < 2%). In conclusion, the developed strategy highlights the significance of combining high-resolution mass spectrometry with chromatographic separation for added confidence in the identification of isomers.
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•Sterilised green coffee beans were fermented with S. cerevisiae or P. kluyveri.•Fermentations led to direct and indirect sensory modulation in roasted coffees.•The yeast ...fermentations raised fruity aroma in roasted coffee through ester production.•S. cerevisiae fermentation also elevated nutty aroma in the roasted coffee.
Direct fermentations of sterilised green coffee beans by monocultures of Saccharomyces cerevisiae and Pichia kluyveri were investigated for coffee flavour biotransformation. During fermentation, fruity esters were generated in the green coffee beans by yeasts. 2-Phenylethyl acetate was elevated by 1.1 mg/kg and 0.03 mg/kg in P. kluyveri- and S. cerevisiae-fermented green beans, respectively, as compared to the untreated sample. Ethyl octanoate (0.51 mg/kg) and isoamyl acetate (1.69 mg/kg) only existed in S. cerevisiae- and P. kluyveri-fermented green beans, respectively. After roasting, higher levels of 2-phenylethyl acetate were detected in fermented coffees, and ethyl octanoate was found only in the S. cerevisiae-fermented sample, despite the loss of isoamyl acetate in P. kluyveri-fermented coffees during roasting. The fruity esters generated by the yeasts during green coffee bean fermentations were directly transferred to the volatile profiles formed after roasting and enhanced the fruity attribute in the roasted coffees, with a more noticeable effect observed from S. cerevisiae fermentation. Higher productions of N-heterocyclic volatiles occurred during roasting of S. cerevisiae-fermented coffees and contributed to elevated nutty and roasted aromas. S. cerevisiae and P. kluyveri are considered suitable starter cultures for controlled coffee flavour biotransformation through controlled fermentations of green coffee beans.
•Fungal fermentation was performed on green canephora coffee beans.•Fungal fermentation modulated free sugars and amino acids content in green canephora coffee beans.•Significant differences were ...observed in the caffeoylquinic acid (CQA) and polyphenol content of the fermented beans.•Increased generation of Maillard reaction products such as pyrazines and pyrroles.
In this study, the effects of fungal fermentation on green canephora coffee beans were evaluated by observing the changes to selected non-volatile parameters before roasting, and subsequently the volatile profile after roasting. Solid-state fermentation (SSF) by Aspergillus spp. and Mucor spp. on green canephora coffee beans was shown to modulate the contents of free sugars, free amino acids and polyphenolic compounds such as caffeoylquinic acids (CQAs). Significant strain-specific differences were observed in the contents of aroma compounds after roasting. A significant increase in pyrazines was observed in the Aspergillus oryzae-fermented samples, while higher levels of furans were detected in the Mucor plumbeus-fermented samples. The present work shows that fungal fermentation of green canephora coffee beans is a potentially promising method for the modulation and improvement of coffee flavour and aroma.
Green tea infusion was fermented with probiotic yeast (Saccharomyces boulardii CNCM I-745), probiotic lactic acid bacteria (LAB) (Lactiplantibacillus plantarum 299V) and a mixed culture of S. ...boulardii CNCM I-745 and L. plantarum 299V. Co-inoculation of yeast and LAB remarkably enhanced the survival of LAB in probiotic-fermented tea. Meanwhile, co-culturing enhanced the aroma compound generation; ethyl esters with fruity notes arose in both yeast monoculture and co-culture fermented teas. Compared to monoculture fermentations, co-fermentation elevated the amounts of methyl salicylate, geraniol and 2-phenylethyl alcohol to higher levels, and consumed lactic acid produced by L. plantarum to a lower level. The findings from this research suggest that fermentation of tea infusion with probiotics would be an innovative way to modulate tea flavor and develop a novel tea beverage with high counts of live probiotics.
•Green tea infusion was transformed by probiotic yeast and lactic acid bacteria.•Co-inoculation of S. boulardii and L. plantarum enhanced survival of L. plantarum.•Co-inoculation of S. boulardii and L. plantarum boosted aroma compounds in fermented tea infusion.•Co-inoculation alleviated acid stress on L. plantarum by consuming lactic acid.
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•Sterilised green coffee beans were fermented by two wine yeasts with or without Lc. lactis.•Yeast coculture of S. cerevisiae and P. kluyveri boosted ester content.•The mixed culture ...fermentations created coffee with pleasant fruit and winey aroma.•Lactococcus fermentation raised caramel aroma in roasted coffee.•Use of lactococcus with the yeast coculture further elevated the aroma-enhancing effect.
This study attempted to achieve coffee flavour biotransformation through controlled fermentation of sterilsed green coffee beans with a coculture of Saccharomyces cerevisiae and Pichia kluyveri (FYco) and a sequential inoculation of Lc. lactis subsp. cremoris and the yeast coculture (FLYco). Isoamyl acetate, 2-phenylethyl acetate, and ethyl octanoate were produced by 5.76, 1.35 and 0.54 mg/kg, respectively, in FYco fermented green coffee beans. Compared to the green coffee bean fermented by the yeast monocultures in previous study, FYco led to a 1.2- and 4.1-times elevation in production of isoamyl acetate and 2-phenylethyl acetate, respectively. FLYco further increased acetate ester production by more than 2 times relative to FYco. The esters produced in FYco and FLYco partially survived the roasting process and imparted the roasted coffees with considerable fruity and winey aromas. The lactic acid fermentation in FLYco increased the acidity in green coffee beans, which promoted the formation of caramel-smelling furfurals and preservation of acidity and sweetness in the roasted coffees. Apart from the mere additions of flavour modification from individual strains, the proper combination of multiple strains can result in synergistic effects that enhanced the modulating activities of individual strains and further enhance flavour complexity of the resulted coffee.
To achieve controlled coffee flavour biotransformation, direct fermentations of sterilized green coffee beans by a lactic acid bacterium (LAB), Lactococcus lactis subsp. cremoris, with and without ...0.5% w/w glucose supplementation were investigated. The major metabolic activity of Lc. lactis subsp. cremoris was lactic acid production, and 2,3-butanedione (diacetyl) was also formed from amino acid metabolism and mixed acid fermentation. Glucose supplementation boosted lactic acid production but repressed 2,3-butanedione formation. The modifications of flavour-related constituents in green coffee beans were translated into modulations of roasted coffee flavour. The glucose-supplemented- and non-supplemented-fermented coffees features enhanced productions of O-heterocyclic and N-heterocyclic volatiles upon roasting, respectively. In particular, the highest level of total furfurals of coffees roasted at 235 °C for 12 min was found in glucose-supplemented-fermented sample, which was 1.4-fold of that in the untreated coffee. The 12-min roasted non-supplemented-fermented coffee featured the highest level of pyrazines, which was 2-fold of that in the untreated coffee. Glucose-supplemented fermentation yielded roasted coffee with an enhanced caramel aroma, together with preserved acidity and sweetness. Non-supplemented fermentation resulted in roasted coffee with an elevated nutty aroma. The undesirable smokiness in the untreated coffee was reduced by both fermentations.
•Direct fermentation of sterilized green coffee beans with Lactococcus lactis subsp. cremoris w/o glucose supplementation.•Fermentations led to targeted sensory modulation in roasted coffee.•Glucose-added fermentation raised caramel aroma in roasted coffee.•Non-supplemented fermentation elevated nutty aroma in roasted coffee.
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