Valorization of sugarcane bagasse and sugar beet molasses using Kluyveromyces marxianus for producing value-added aroma compounds via solid-state fermentation

Abstract

The growing demand for natural products has favored the development of bioprocesses for obtaining value-added products in the fragrance and flavor sector. Solid-state fermentation (SSF) of agro-industrial residues together with generally recognized as safe (GRAS) strains like Kluyveromyces marxianus appears as a remarkable alternative for producing aroma compounds. In this study, a continuous air supplied system was used for optimizing the production of fruit-like compounds via SSF of a mixture of sugarcane bagasse/sugar beet molasses employing K. marxianus. The main operational parameters were evaluated to identify the best

Bioproduction of 2-phenylethanol and 2-phenethyl acetate by Kluyveromyces marxianus through the solid-state fermentation of sugarcane bagasse

“…The composition of the exhaust gases of the fermented substrate was determined by thermal desorption gas chromatography mass spectrometry (TD-GC-MS) as described in (Martínez et al 2017) (See details in supplementary material, section 1).…”

“…First, a 2 4 factorial design (design N°1) was used to assess the effects of temperature (T), specific air flow rate (SAFR), L-Phe dose (Pd) and sugar beet molasses dose (Md) (Table S1). pH, MC and inoculum load (IL) were kept at 5.3, 68% and 10 8 CFU g -1 TS respectively, based on our previous results (Martínez et al 2017). T and Pd were valued between 30-37°C and 1.55 and 3.1% (dry basis), respectively, considering the results of former studies (Etschmann et al 2003;Garavaglia et al 2007;Gao and Daugulis 2009), while SAFR and Md were changed in the intervals 0.05-0.10 L h -1 g -1 TS and 0-20% (dry basis) according to our preliminary results (Martínez et al 2017).…”

“…Here, T, SAFR, Md and IL were set at 30°C, 0.10 L h -1 g -1 TS, 5% and 10 8 CFU g -1 TS respectively, based on the previous results. In this case, pH was assessed between 4.8-6.0, according to previous studies (Etschmann and Schrader 2006;Garavaglia et al 2007), MC from 60-76% (based on the range previously established by (Martínez et al 2017)), and Pd was set between 3 and 6 % (dry basis) as a manner of supplying an excess of precursor. As shown in Fig.…”

“…In this sense, solid-state fermentation (SSF) has proven its efficiency as an environmentally friendly and economical tool for the valorization of several organic solid wastes (Longo and Sanroman 2006;Yazid et al 2017). In particular, valuable aroma compounds have been previously obtained through the SSF of agroindustrial residues (Medeiros et al 2001;Martínez et al 2017) but, to our knowledge, no attempts to produce 2-PE and 2-PEA via SSF have been reported yet.…”

“…For instance, SSF commonly presents high production rates and yields (Barrios-González 2012), and it can be run with low-priced raw materials (Soccol et al 2017). If continuous air supply is used, it would also serve for stripping out a given fraction of the volatile and semi-volatile compounds from the solid matrix (Martínez et al 2017), favoring the further aroma compounds production. In this sense, 2-PE and 2-PEA could be produced in simple reaction systems starting with organic wastes as raw material, applying the current thought "from trash to treasure" (Berger 2015).…”