Levan Production by Suhomyces kilbournensis Using Sugarcane Molasses as a Carbon Source in Submerged Fermentation.

The valorization of byproducts from the sugarcane industry represents a potential alternative method with a low energy cost for the production of metabolites that are of commercial and industrial interest. The production of exopolysaccharides (EPSs) was carried out using the yeast Suhomyces kilbournensis isolated from agro-industrial sugarcane, and the products and byproducts of this agro-industrial sugarcane were used as carbon sources for their recovery. The effect of pH, temperature, and carbon and nitrogen sources and their concentration in EPS production by submerged fermentation (SmF) was studied in 170 mL glass containers of uniform geometry at 30 °C with an initial pH of 6.5. The resulting EPSs were characterized with Fourier-transform infrared spectroscopy (FT-IR). The results showed that the highest EPS production yields were 4.26 and 44.33 g/L after 6 h of fermentation using sucrose and molasses as carbon sources, respectively. Finally, an FT-IR analysis of the EPSs produced by S. kilbournensis corresponded to levan, corroborating its origin. It is important to mention that this is the first work that reports the production of levan using this yeast. This is relevant because, currently, most studies are focused on the use of recombinant and genetically modified microorganisms; in this scenario, Suhomyces kilbournensis is a native yeast isolated from the sugar production process, giving it a great advantage in the incorporation of carbon sources into their metabolic processes in order to produce levan sucrose, which uses fructose to polymerize levan.

Effect of calcium hydroxide mixed with preservatives on physicochemical characteristics and sensory shelf-life of corn tortilla.

BACKGROUND: The objective of the study was to evaluate the physicochemical characteristics and shelf-life of corn tortilla stored at room temperature (25 °C) using aw modifiers (propylene glycol and glycerol) and pH modifiers (fumaric acid and sodium benzoate) as preservatives combined with calcium hydroxide. Detection thresholds were used to determine the maximum preservative concentration and calcium hydroxide. Physicochemical characterization and sensory evaluation were used to determine the stability and sensory shelf-life of tortillas. RESULTS: Control, calcium hydroxide, calcium hydroxide + fumaric acid, calcium hydroxide + glycerol, calcium hydroxide + propylene glycol, and calcium hydroxide + sodium benzoate treatments had rounded half-lives of 1, 2, 1, 2, 2, and 2 days respectively. Glycerol combined with calcium hydroxide resulted in tortillas with lower pH variations over time. Mold presence was the critical attribute causing tortilla rejection. CONCLUSION: The use of aw modifiers had a better effect in preserving corn tortilla, as the concentration of pH modifiers at detection threshold levels was not able to reach an optimum performance when combined with calcium hydroxide. © 2021 Society of Chemical Industry.

Technique for order of preference by similarity to ideal solution (TOPSIS) method for the generation of external preference mapping using rapid sensometric techniques.

BACKGROUND: External preference mapping is a powerful tool to explain consumer preference or rejection. Combining the technique for order of preference by similarity to ideal solution (TOPSIS) multicriteria analysis with rapid descriptive techniques can improve preference map (PREFMAP) results. This study was conducted to compare the PREFMAPs generated with rapid descriptive flash profile (FP), check-all-that-apply (CATA), and Napping® versus PREFMAPs constructed with FP-TOPSIS, CATA-TOPSIS, and Napping-TOPSIS. RESULTS: Only 38.46%, 63.66%, and 42% of sensory attributes initially generated by FP, CATA, and Napping techniques respectively were considered for the determination of their weight W and allocation as positive or negative in the TOPSIS technique. The PREFMAPs constructed with FP-TOPSIS, CATA-TOPSIS, and Napping-TOPSIS presented a better explanation of the preference and rejection than the PREFMAPs directly generated with rapid sensory techniques. The results of the multiple factor analysis and coefficient Rv indicated similarities in the sensory vocabularies used after the TOPSIS technique. CONCLUSION: The combination of the TOPSIS technique with rapid sensory techniques is a reliable alternative for the construction of PREFMAPs in order to identify the sensory attributes responsible for preference and rejection of food products. © 2020 Society of Chemical Industry.