Biovalorization of spent Konacha tea leaves via single-culture fermentation involving wine yeasts and lactic acid bacteria.

AIMS: The objective of this study was to explore the potential of fermentation as a biovalorization strategy for spent tea leaves (STL), a major agrifood waste generated from the tea extraction industry. Fermentation by wine yeasts or lactic acid bacteria (LAB) has shown promising results in previous studies across various substrates. METHODS AND RESULTS: Konacha (green tea) STL slurries were inoculated with single strains of wine yeasts or LAB respectively. After a 48-h fermentation, changes in selected nonvolatile and volatile compositions were evaluated. Fermentation by LAB increased organic acid content by 5- to 7-fold (except Lactobacillus fermentum) and modulated the composition of major tea catechins, whereas wine yeast fermentation resulted in a 30% increase in amino acid content. Strain-specific production of specific volatile compounds was also observed such as butanoic acid (L. fermentum), isoamyl acetate (Pichia kluyveri) and 4-ethylphenol (L. plantarum). CONCLUSIONS: Both volatile and nonvolatile compound compositions of Konacha STL were successfully modified via wine yeast and LAB fermentation. SIGNIFICANCE AND IMPACT OF STUDY: Our findings indicate that Konacha STL is a suitable medium for biovalorization by wine yeasts or LAB via the generation of commercially useful volatile and nonvolatile compounds. Future optimizations could further render fermentation an economically viable strategy for the upcycling of STL.

Recent advances in analytical strategies for coffee volatile studies: Opportunities and challenges.

Coffee has attracted significant research interest owing to its complex volatile composition and aroma, which imparts a pleasant sensorial experience that remains challenging to analyse and interpret. This review summarises analytical challenges associated with coffee's volatile and matrix complexity, and recent developments in instrumental techniques to resolve them. The benefits of state-of-the-art analytical techniques applied to coffee volatile analysis from experimental design to sample preparation, separation, detection, and data analysis are evaluated. Complementary method selection coupled with progressive experimental design and data analysis are vital to unravel the increasing comprehensiveness of coffee volatile datasets. Considering this, analytical workflows for conventional, targeted, and untargeted coffee volatile analyses are thus proposed considering the trends towards sorptive extraction, multidimensional gas chromatography, and high-resolution mass spectrometry. In conclusion, no single analytical method addresses coffee's complexity in its entirely, and volatile analysis must be tailored to the key objectives and concerns of the analyst.

Ingredients, Processing, and Fermentation: Addressing the Organoleptic Boundaries of Plant-Based Dairy Analogues.

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.

Effect of solid-state fungal fermentation on the non-volatiles content and volatiles composition of Coffea canephora (Robusta) coffee beans.

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.