Identification of New Natural Sources of Flavour and Aroma Metabolites from Solid-State Fermentation of Agro-Industrial By-Products

Abstract

Increasing consumer demand for natural flavours and fragrances has driven up prices and increased pressure on natural resources. A shift in consumer preference towards more sustainable and economical sources of these natural additives and away from synthetic production has encouraged research into alternative supplies of these valuable compounds. Solid-state fermentation processes support the natural production of secondary metabolites, which represents most flavour and aroma compounds, while agro-industrial by-products are a low-value waste stream with a high potential for adding value. Accordingly, four filamentous fungi species with a history of use in the production of fermented foods and food additives were tested to ferment nine different agro-industrial by-products. Hundreds of volatile compounds were produced and identified using headspace (HS) solid-phase microextraction (SPME) coupled to gas chromatography–mass spectrometry (GC–MS). Four compounds of interest, phenylacetaldehyde, methyl benzoate, 1-octen-3-ol, and phenylethyl alcohol, were extracted and quantified. Preliminary yields were encouraging compared to traditional sources. This, combined with the low-cost substrates and the high-value natural flavours and aromas produced, presents a compelling case for further optimisation of the process.

Miniaturized Solid Phase Extraction Techniques Applied to Natural Products

“…Although not reported for volatile compounds in natural products, CAR/PDMS coating appears to be the most suitable for low MW analytes [13][14][15][16]. Lindsay et al [17] screened volatile profiles from food-grade agro-industrial by-products, such as apple, orange, carrot pomace, onion pulp, and kiwifruit peels. All extractions were carried out using HS-SPME with a 1 cm 50/30 µm DVB/CAR/PDMS (Supelco) fibre coupled with GC-MS.…”

Fermentation as a Strategy to Valorize Olive Pomace, a By-Product of the Olive Oil Industry

“…Fermentation is a biochemical process alternative to produce a natural source of flavor and aroma metabolites, making the final product more attractive for consumption, with market acceptability. Lindsay et al [87] verified that secondary metabolites from the fermentation of by-products had high potential for adding value. The study was carried out using filamentous fungi and diverse byproducts, such as apple pomace, onion pulp, orange pomace, kiwifruit peels, carrot pomace, and olive pomace.…”

The Wine Industry By-Products: Applications for Food Industry and Health Benefits

“…Many of the volatile compounds found in GP have pleasant aromatic notes related to herbal, fruity, or floral perception [ 25 ]. Recently, Lindsay and co-workers [ 29 ] reported that some filamentous fungi find grape marc could be valuable sources of aromas. Aspergillus niger and Aspergillus oryzae are able to produce metabolites also associated with pleasant flavors, such as herbal notes, citrus (3-octanol), lavender, nectarine (3-octanone), cinnamon (E-cinnemaldehyde), or tropical fruits (ethyl tiglate) [ 29 ].…”

“…Recently, Lindsay and co-workers [ 29 ] reported that some filamentous fungi find grape marc could be valuable sources of aromas. Aspergillus niger and Aspergillus oryzae are able to produce metabolites also associated with pleasant flavors, such as herbal notes, citrus (3-octanol), lavender, nectarine (3-octanone), cinnamon (E-cinnemaldehyde), or tropical fruits (ethyl tiglate) [ 29 ]. The popularity of fruit teas is increasing in the world because of their antioxidant properties and their attractive taste.…”