Fermentative Production of Volatile Metabolites Using Brettanomyces bruxellensis from Fruit and Vegetable By-Products

Abstract

Natural sources of flavour and aroma compounds are highly sought by the modern consumer; however, traditional sources are often low-yielding, and global supply is often outstripped by consumer demand. Fermentation is a favourable route by which natural flavours and fragrances can be produced. A non-Saccharomyces yeast, Brettanomyces bruxellensis, was investigated for its fermentative potential for the production of flavour and aroma metabolites from juice industry by-products: apple pomace, carrot pomace, and orange pomace. Submerged solid-substrate fermentations were carried out using sterile by-products without nutrient supplementation. Gas chromatography–mass spectrometry was used for volatile metabolite profiling of fermented substrates. One compound of interest, phenylethyl alcohol (rose fragrance), was extracted and quantified using GC-MS at a yield of 2.68 g/kg wet carrot pomace weight. This represents a novel, natural production strategy for phenylethyl alcohol compared to the traditional steam distillation of Rosa domascus sp. petals.

Role of Microbial Fermentation in the Bio-Production of Food Aroma Compounds from Vegetable Waste

“…Other molecules responsible for sweet notes were also obtained in combination with other aroma compounds from the fermentation of (i) cajá and umbu residues with the fungus Auriporia aurulenta sp. [31], (ii) apple and orange pomace by Brettanomyces bruxellensis CCT 3469 [32], and (iii) rice bran with a strain of Rhizopus oligosporous sp. [33].…”

“…Submerged solid-substrate fermentations of apple, orange, and carrot pomace by the yeast Brettanomyces bruxellensis strain CCT 3469 also produced esters with a fruity note (Table 2) [32]. An aliquot of sterile wet substrate was added with sterile distilled water, and inoculated with the pre-inoculum resuspended in 10 mL saline: the 1 L volume Erlenmeyer flasks were then incubated under the conditions specified in Table 4.…”

“…An aliquot of sterile wet substrate was added with sterile distilled water, and inoculated with the pre-inoculum resuspended in 10 mL saline: the 1 L volume Erlenmeyer flasks were then incubated under the conditions specified in Table 4. The fermentation occurred with and without the supplementation of L-phenylalanine (7 g/L) [32]. The production of esters with fruity notes was due to the fact that, during the fermentation, the free reducing sugars available in the apple, orange, and carrot pomaces were used.…”

“…2-Phenylethyl acetate and phenylethyl alcohol were also produced by fermenting the pomace of apples, oranges, and carrots with B. bruxellensis CCT 3469 strain (Table 2) [32]. Other molecules imparting a floral note were also produced in combination with other aroma compounds by fermenting other vegetable residues, such as cajá residues and melon by-products (Table 2).…”

“…Ethyl oleate, 9,12-octadecadienoic acid (Z,Z), and ethyl linoleate, which are responsible for fatty notes, were the esters which were mostly produced. Following the submerged solid-substrate fermentation of apple, orange, and carrot pomace by the yeast Brettanomyces bruxellensis strain CCT 3469, under the conditions specified in Table 4, admixtures of aroma compounds were obtained [32]. The highest amount of aroma compounds produced during the fermentative process was observed in carrot pomace: 160 compounds, compared to 142 compounds in orange pomace and 106 in apple pomace.…”