Insights in cyanobacteria lipidomics: A sterols characterization from Phormidium autumnale biomass in heterotrophic cultivation.

Sterol profiles were obtained from cyanobacteria Phormidium autumnale, cultivated in a heterotrophic system using three distinct sources of carbon: glucose, sucrose, and agroindustrial slaughterhouse wastewater. A simultaneous saponification-extraction ultrasound-assisted method was performed to determine sterol and other non-saponified compounds in the dry biomasses. A total of 24 compounds were observed in the biomasses, including hope-22,29-en-3-one, squalene, and 22 other sterols. Using wastewater as a carbon source, the microalgae biomass produced a diversity of sterols such as stigmasterol (455.3 µg g-1) and ß-sitosterol (279.0 µg g-1). However, with glucose it is possible to produce ergosterol (1033.3 µg g-1). Squalene was found in all the cultures, with 1440.4 µg g-1, 225.4 µg g-1, and 425.6 µg g-1 for glucose, sucrose, and slaughterhouse wastewater biomasses, respectively. Several intermediate compounds from those sterols were found. These data provide the construction of the sterol metabolism according to the literature for P. autumnale heterotrophically cultured.

Ultrasound: A new approach to reduce phosphate content of meat emulsions.

Meat emulsions with a reduction of 0, 25, 50, 75, and 100% of phosphate levels were produced. Soon after filling, the pieces were sonicated in an ultrasonic bath (normal mode, 60% amplitude, 25 KHz frequency, 230 W acoustic power, and 33 W L-1 volumetric power) for 0, 9, and 18 min. The technological, oxidative, and sensory quality was evaluated. The reduction of the phosphate content in the non-sonicated samples led to a decrease in the cooking yield and emulsion stability and impaired the texture profile, and the oxidative and sensory quality of the samples. Although the 9-min ultrasound treatment was not effective to compensate for defects caused by the phosphate reduction, the application for 18 min improved the technological quality and did not increase the lipid oxidation. In addition, it allowed reducing most of the sensory defects caused by the reduction of 50% of the phosphate level. Therefore, the US can be useful to produce low-phosphate meat emulsions.

Polar and non-polar intracellular compounds from microalgae: Methods of simultaneous extraction, gas chromatography determination and comparative analysis.

A method to simultaneously extract polar (PC) and non-polar compounds (NPC) from microalgae was developed for further determination of intracellular metabolites by gas chromatography. The proposed method was validated and used to characterize two Chlorophyceae, Chlorella vulgaris and Scenedesmus obliquus, and two Cyanobacteria, Aphanothece microscopica Nagëli and Phormidium autumnale. The compounds were extracted with a reduced amount of organic solvent mixture (methanol-chloroform), compared to the reference method, under different conditions of homogenization and/or cell disruption. The NPC were derivatized by acid catalysis, whereas the PC fraction was derivatized using N-methyl,N-tert-Butyldimethylsilyltrifluoroacetamide (MTBSTFA) in alkaline medium. The following parameters for method validation were considered: selectivity, linearity, limit of detection (LOD), limit of quantitation (LOQ), precision, and accuracy. All methods of homogenization and cell disruption extracted both PC and NPC from Chlorophyceae and Cyanobacteria. Derivatization of PC presented satisfactory validation parameters. Eleven fatty acids, six free amino acids, and three organic acids were found within the evaluated microalgae species, succinic, malic, and citric acids, important intermediates of the tricarboxylic acid cycle. Glutamic acid was the amino acid found in greatest quantities in all species. Chlorophyceae presented a higher concentration of unsaturated fatty acids, while Cyanobacteria had more saturated fatty acids. Thus, the proposed method was suitable to metabolically characterize both PC and NPC from microalgae.