Fermentation of araticum, baru, and pequi by-products by probiotic strains: effects on microorganisms, short-chain fatty acids, and bioactive compounds.

Fruit by-products, due to their unique chemical composition containing dietary fibers and bioactive compounds, may favor the growth of probiotic strains. This study evaluated the fermentation of araticum, baru, and pequi by-products using Lactobacillus acidophilus (La-5, LA3, and NCFM) and Bifidobacterium animalis subsp. lactis (Bb-12) probiotic strains. We assessed probiotic viability, short-chain fatty acid levels, and bioactive compound levels after 48 h of fermentation. Araticum and pequi by-products led to counts higher than 6 log CFU/mL after 48-h fermentation for all Lactobacillus strains, but only the araticum by-product supported the growth of the Bb-12 strain. Fermentation of araticum by-product resulted in greater amounts of acetate (39.97 mM for LA3 and 39.08 mM for NCFM) and propionate (0.20 mM for NCFM), while baru by-product showed greater amounts of butyrate (0.20 mM for La-5 and Bb-12). Fermentation of araticum and baru by-products resulted in an increase in bioactive compounds, with the latter showing total phenolic compounds and antioxidant activity from 1.4 to 1.7 and from 1.3 to 3.1 times higher, respectively, than the negative control treatment. Araticum by-product exhibited a higher potential for prebiotic effects, and fermentation by the tested probiotic strains is essential to increase bioactive compound levels.

Influence of ozonolysis time during sugarcane pretreatment: Effects on the fiber and enzymatic saccharification.

Modifications in sugarcane bagasse (SCB) from ozonolysis (O) NaOH (B) and ultrasound (U) (OBU) treatment for cellulosic ethanol production by enzymatic hydrolysis, were evaluated when increasing the exposure time of SCB to ozone. The lignin, cellulose, and hemicellulose after treatment were quantified: lignin removal and a consequent increase in cellulose content were shown using an infrared spectroscopic technique (ATR-FTIR) and chemical characterization. X-ray diffraction analysis (XRD) proved that OBU treatment does not affect the crystalline cellulose portion and electron microscopy techniques established that the fiber region most affected by the OBU treatment was the secondary cell wall, where the greatest lignin content is located. For OBU-60 treatment the lignin content was reduced and consequently there was a significant increase in cellulose content. After enzymatic hydrolysis, this pretreated SCB released 418mgglucose/g, corresponding to six times more than untreated SCB and a yield of 93% of the cellulose available.

Effect of pretreatment and enzymatic hydrolysis on the physical-chemical composition and morphologic structure of sugarcane bagasse and sugarcane straw.

The present work aimed to study the effect of the pretreatment of sugarcane bagasse and straw with microwave irradiation in aqueous and acid glycerol solutions on their chemical composition, fiber structure and the efficiency of subsequent enzymatic hydrolysis. Thermogravimetric analysis showed that the pretreatment acted mainly on the lignin and hemicellulose fractions of the bagasse, whereas, in the straw, lesser structural and chemical changes were observed. The images from transmission electron microscopy (TEM) revealed that treating bagasse and straw with acid glycerol solution loosened the cell walls and there was a breakdown in the pit membrane. The treated material was submitted to hydrolysis for 72h and higher yields of reducing sugars were observed compared to the untreated material (250.9mg/g from straw and 197.4mg/g from bagasse). TEM images after hydrolysis confirmed the possible points of access of the enzymes to the secondary cell wall region of the pretreated biomass.

Evaluation of microwave-assisted pretreatment of lignocellulosic biomass immersed in alkaline glycerol for fermentable sugars production.

A pretreatment with microwave irradiation was applied to enhance enzyme hydrolysis of corn straw and rice husk immersed in water, aqueous glycerol or alkaline glycerol. Native and pretreated solids underwent enzyme hydrolysis using the extract obtained from the fermentation of Myceliophthora heterothallica, comparing its efficiency with that of the commercial cellulose cocktail Celluclast®. The highest saccharification yields, for both corn straw and rice husk, were attained when biomass was pretreated in alkaline glycerol, method that has not been previously reported in literature. Moreover, FTIR, TG and SEM analysis revealed a more significant modification in the structure of corn straw subjected to this pretreatment. Highest global yields were attained with the crude enzyme extract, which might be the result of its content in a great variety of hydrolytic enzymes, as revealed zymogram analysis. Moreover, its hydrolysis efficiency can be improved by its supplementation with commercial ß-glucosidase.