The best conditions for in vitro sucrose hydrolysis based on invertase from Candida guilliermondii (ICg) were studied and the kinetic parameters KM,Vmax, and thermal stability of ICg were determined. Candida guilliermondii (Cg) yeast isolated and lyophilized from peach solid wastes was identified using the API 20C AUX method. Subsequently, the Cg was submitted to an autolysis process using NaHCO3 at 200 mM under 200 rpm stirring and 40 °C for 24 h. The enzyme extracts obtained were recovered through precipitation with acetone followed by dialysis and ion-exchange chromatography. The extract purified through precipitation with acetone had activity of 27.7 U.mg-1 and 56% recovery whereas the chromatography process yielded 46.5 U.mg-1 and 44.8%. The optimal sucrose hydrolysis conditions were pH 5.0 and 50 °C, resulting in KM of 30.5 mM and 28.7 mM sucrose, respectively, at 25 °C and 50 °C, both with Michaelian behavior. Thermal inactivation of ICg exhibited first-order apparent kinetics and its residual activity was typically linear between 40 °C and 70 °C. Three isoenzymes were detected through electrophoresis.

The identification of yeasts isolated from spoiled Jubileu peach puree using the API 20C AUX method and a commercial yeast as witness were studied. Subsequently, the yeast's growth potential using two batch culture treatments were performed to evaluate number of colonies (N), reducing sugar concentration (RS), free-invertase (FI), and culture-invertase activity (CI). Stock cultures were maintained on potato dextrose agar (PDA) slants at 4 °C and pH 5 for later use for batch-culture (150 rpm) at 30°C for 24 h, then they were stored at 4 °C for subsequent invertase extraction. The FI extract was obtained using NaHCO 3 as autolysis agent, and CI activity was determined on the supernatant after batch-cultured centrifugation. The activity was followed by an increase in absorbance at 490 nm using the acid 3,5-DNS method with glucose standard. Of the four yeasts identified, Saccharomyces cerevisiae was chosen for legal reasons. It showed logarithmic growth up to 18 h of fermentation with positive correlation CI activity and inverse with RS. FI showed greater activity by the end of the log phase and an inverse correlation with CI activity. Finally, it was concluded that treatment "A" is more effective than "B" to produce invertase (EC 3.2.1.26).Keywords: spoiled peach puree; invertase; Saccharomyces cerevisiae; autolysis.Pratical Application: Potential production of glucose and fructose syrup by yeast invertases from spoiled peach pure.

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RESUMO -O objetivo deste trabalho foi verificar o efeito do pH, da temperatura e da concentração de sacarose na atividade da invertase de Candida guilliermondii (ICg) extraída de resíduos de pêssego e identificada pelo sistema API 20C AUX. Os extratos enzimáticos foram obtidos com solução de bicarbonato de sódio, purificados por precipitação com acetona e as isoenzimas foram detectadas por eletroforese em gel de poliacrilamida a 6% usando BSA como marcador de proteína. A atividade enzimática e o teor de proteínas foram determinados com os métodos do ácido 3,5-DNS e Lowry respectivamente. A recuperação da invertase da ICg foi de 56% com atividade ótima a pH 5 a 50°C e na eletroforese foram detectadas três frações enzimáticas. A cinética enzimática demonstrou que a invertase da ICg teve comportamento michaeliano sendo mais específica a 50°C do que a 25°C.