Resumo Estudaram-se as melhores condições de hidrólise da sacarose in vitro a partir da invertase de Candida guilliermondii (ICg), também se determinou os parâmetros cinéticos KM, Vmax e a estabilidade térmica da ICg. A levedura Candida guilliermondii (Cg) extraída, isolada e liofilizada de resíduo de pêssego foi identificada usando o método API 20C AUX. Posteriormente, a levedura Cg foi submetida a um processo de autólise, usando NaHCO3 a 200 mM sob agitação a 200 rpm e 40°C, por período de 24 horas. Os extratos enzimáticos obtidos foram recuperados por precipitação com acetona seguido de diálise e cromatografia de troca iônica. O extrato purificado por precipitação com acetona teve a atividade de 27,7 U.mg-1 e 56% de recuperação, sendo que, por cromatografia, obtiveram-se 46,5 U.mg-1 e 44,8%. As condições ótimas na hidrólise da sacarose foram pH de 5,0 e 50°C, apresentando KM de 30,5/mM e 28,7 mM de sacarose, respectivamente, a 25°C e a 50°C, ambas com comportamento Michaeliano. A inativação térmica da ICg mostrou uma cinética aparente de primeira ordem, e sua atividade residual foi tipicamente linear entre 40°C - 70°C. Por meio de eletroforese, foram detectadas três isoenzimas.

Abstract 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.

Abstract The extraction was performed using an autolysis process where enzymes degrade cell structures and release the cytoplasmic contents to the extracellular medium. The autolysis process was carried out in shake flasks with different agitation speeds (50 - 350 rpm) and the concentration of sodium bicarbonate (50 -350 mM NaHCO3) at 40 ° C for 24 hours, using a central composite design adapted for two variables and five levels and response surface methodology (RSM) and canonical analysis to define the optimal conditions of extraction of invertase S. cerevisiae from peach puree (ISc). In great condition extraction, we studied the effect of the liofilization and purified in the invertase activity using colorimetric method of 3,5-dinitrosalicílico (DNS) at 490 nm to monitor their activity. One unit (U) defined as 1 mg glicose.min-1. Protein concentrations were determined by Lowry and invertase comercial yeast (ICY). The influence of concentration NaHCO3 and stirring speed to extract the enzyme invertase showed linear effect, quadratic and interactive. The polynomial model of second order could explain the extraction phenomenon of invertase with R2 of 0.80, with significantly dependent on both variables activity. The maximum extraction was observed in the experimental center point (200 mM NaHCO3 and 200 rpm) with an activity of 14.7 U.mg-1. The stationary point is a point of maximum extraction, differing by at least 10% of the experimental center point. Based on these characteristics, the optimal conditions for extraction of S. cerevisiae invertase from peach puree (ISc) are 200 mM NaHCO3 as autolysis agent, 200 rpm orbital shaking at 40ºC for 24 hours and freeze-dried using biomass. Ethanol is more effective than acetone for recovery of specific activity.

Resumen La extracción fue realizada a través de un proceso de autolisis, donde las enzimas degradan las estructuras celulares y liberan el contenido citoplasmático al medio extracelular. El proceso de autolisis fue realizado en shaker con diferentes velocidades de agitación (50 - 350 rpm) y concentraciones de bicarbonato de sodio (50 -350 mM NaHCO3) a 40 °C por 24 horas, usando un diseño experimental compuesto central adaptado para dos variables y cinco niveles, así como una metodología de superficie de respuest a (MSR) y análisis canónico para definir las condiciones óptimas de extracción de invertasa de S. cerevisiae aislada de puré de durazno (ISc). En la condición optima de extracción, se estudió el efecto de la liofilización y purificación en la actividad de la invertasa, usando el método colorimétrico del ácido 3,5-dinitrosalicílico (DNS) a 490 nm para acompañar su actividad expresada en unidades. Una unidad (U) es definida como 1 mg glucosa.min-1. El valor de proteínas fue cuantificado por el método Lowry y la invertasa de levadura comercial (ILC) como testigo. La influencia de la concentración de NaHCO3 y de la velocidad de agitación en la extracción de la enzima invertasa indicó efecto lineal, cuadrático e interactivo. El modelo de forma polinómica de segundo orden explicó el fenómeno de extracción de la invertasa con un R2 de 0,80, y con actividad significativamente dependiente de ambas variables. La máxima extracción fue observada en el punto central experimental (200 mM NaHCO3 y 200 rpm) con una actividad de 14,7 U.mg-1. El punto estacionario es un punto de máxima extracción, el cual difiere en menos de 10% del punto central experimental. De acuerdo a estas características, las óptimas condiciones para extracción de la invertasa de S. cerevisiae aislada de puré de durazno son 200 mM NaHCO3 como agente de autolisis, 200 rpm de agitación orbital a 40oC durante 24 horas y usando una biomasa de levaduras liofilizadas. El etanol es más efectivo que la acetona para la recuperación de la actividad específica.

Abstract 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 NaHCO3 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).

RESUMO A presença dos glicosídeos cianogênicos amigdalina e prunassina, e de ß-glucosidases as quais hidrolisam estas moléculas, faz com que a amêndoa de pêssego apresente potencial toxidez pela possibilidade de liberação de cianeto de hidrogênio, impossibilitando a utilização da amêndoa e de subprodutos como alimentos. Até o presente, não há dados disponíveis na literatura sobre as condições de hidrólise das enzimas presentes neste material. Este trabalho visou a mensurar o conteúdo de amigdalina, e as condições ideais de pH, temperatura e concentração do substrato de extrato bruto de ß-glucosidases para a atuação enzimática, em amêndoas de pêssego. Os resultados demonstraram a presença do glicosídeo na amêndoa de pêssego em níveis semelhantes aos relatados para outras amêndoas. Quanto à atividade de ß-glucosidase, a enzima apresentou Km e Vmáx de 2,7 mmol.L-1 de amigdalina e 0,1407 mmol de glicose.min-1.mg-1 de proteína, respectivamente, valores que indicam menor afinidade pelo substrato amigdalina do que de enzimas purificadas que catalisam as mesmas reações. O pH ótimo da enzima foi o 7,0, porém entre 5,0; 6,0 e 8,0 ainda ocorre elevada atividade. A enzima demonstrou estabilidade nas temperaturas empregadas neste estudo, apresentando máxima atividade a 60ºC. Deste modo, o uso destas alterações não é suficiente para inativação enzimática e utilização segura das amêndoas de pêssego.

ABSTRACT The presence of cyanogenic glycoside amygdalin and prunasin, and of ß-glucosidases which hydrolyze these molecules, causes potential toxicity in peach kernel by the possible hydrogen cyanide release, disabling the use of the kernel and their sub-products as foods. Until now, no data are available in the literature on the conditions of the enzymes hydrolysis present in this material. This study aimed to measure the amygdalin content, and the optimal conditions of pH, temperature and substrate concentration of ß-glucosidases crude extract for the enzymatic activity. The results showed the presence of the glycoside in peach almond in levels similar to those found for other almond kernels. Regarding the activity of ß-glucosidase, the enzyme showed Km and Vmax of 2.7 mmol L-1 of amygdalin and 0.1407 mmol of glicose.min-1.mg-1 of protein respectively, values ??that indicate lower affinity for amygdalin substrate than purified enzymes that catalyze the same reaction. The optimum pH of the enzyme was 7.0, but between 5.0, 6.0 and 8.0 high activity still occurs. The enzyme showed stability at the temperatures employed in this study, with maximum activity at 60 ° C. Thus, the use of these changes is not sufficient for enzyme inactivation and safe use of peach kernels.

The thermal inactivation of yeast isolated from spoiled Jubileu peach puree and that of polyphenoloxidase (PPO) and peroxidase (POD) in cv. Jubileu, which is widely cultivated in southern Rio Grande do Sul state, Brazil, were studied. PPO and POD were extracted using the protein powder method and submitted to partial purification by precipitation followed by dialysis. The enzymatic activity was determined measuring the increase in absorbance at 420 nm for PPO and 470 nm for POD. The yeast used in this investigation was isolated from spoiled Jubileu peach puree at 22 °Brix, with total initial microbial count of 22 × 10² UFCmL- 1. Stock cultures were maintained on potato dextrose agar (PDA) slants at 4 °C and pH 5 for later use for microbial growth. In all cases, kinetic analysis of the results suggests that the thermal inactivation was well described by a first-order kinetic model, and the temperature dependence was significantly represented by the Arrhenius law. Both enzymes were affected by heat denaturation, and PPO was more thermostable. PPO was also more thermosTable than the yeast isolated from peach puree. The D60-values were 1.53 and 1.87 min for PPO and yeast isolated from spoiled Jubileu peach puree, respectively.

Durante o armazenamento, pode ocorrer a perda de compostos voláteis responsáveis pelo aroma e o aumento de compostos indesejáveis, o que ocasiona a perda de qualidade do morango, reduzindo a vida de prateleira e levando à rejeição do produto pelos consumidores. Neste trabalho, foi avaliada a influência do sistema de produção (convencional e orgânico) e do período de armazenamento (0, 2, 5, 8 dias) nas características físicas e químicas (CFQ) e nos compostos voláteis (CV) de morango das cultivares 'Camarosa' e 'Camino Real', utilizando morangos de pomar comercial da região de Pelotas/RS. Os frutos foram colhidos em estádio de maturação comercial e com boa aparência. O planejamento experimental foi casualizado, em triplicata de 15 frutos. Os morangos foram armazenados a T de 1°C, com 90-95% umidade relativa (UR). Foram avaliadas a perda de massa, a coloração instrumental [L*, a*, b* e ângulo hue (H)] , a firmeza, os sólidos solúveis (SS), a acidez titulável (AT), a relação SS/AT, pH e os teores de CV. Os resultados foram submetidos à análise de variância e as diferenças significativas determinadas pelo teste de Tukey (P<0,05). Os resultados revelaram que pH, SS, relação SS/AT, podridões e perda de massa aumentaram durante o armazenamento. A firmeza se manteve irregular e a AT e H diminuíram significativamente. Os teores de CV aumentaram com exceção do acetato de metila (AM). O etanol (Et), o acetaldeído (AA) e o acetato de etila (AE) correlacionaram-se positivamente com o teor de podridões para a cultivar 'Camino Real' do cultivo orgânico. De modo geral o AM correlacionou-se inversamente com o teor de podridões, exceto para a cultivar 'Camino Real' do cultivo convencional. Os morangos de ambas as cultivares podem ser armazenados por cinco dias com qualidade, independente do sistema de produção.

During the storage a loss of volatile compounds responsible for the aroma and an increase of undesirable compounds can occur leading to a decrease in the strawberry quality, a reduction of the shelf life and product rejection by the consumers. In the present work the influence of the planting system (conventional and organic) and the storage period (0, 2, 5 and 8 days) upon physical and chemical characteristics (FCC) as well as on strawberry volatile compounds (VC) in the cultivars 'Camarosa' and 'Camino Real' were evaluated using strawberries from a commercial orchard from Pelotas/RS. The fruits were harvested in a stage of commercial maturation and sound appearance. The experimental planning was randomized, in triplicate of fifteen fruits. The strawberries were stored at 1°C and 90-95% of relative humidity (RH). The mass loss, the instrumental color [L*, a*, b* and hue angle (H)], the firmness, the soluble solids (SS), the titratable acidity (TA), the SS/TA ratio, the pH and VC content were determined. The results were analyzed by analysis of variance and significant differences were determined using Tukey's test (P<0.05). The results show that pH, SS, relation SS/TA, decay and mass loss have increased during storage. The firmness varied irregularly and TA and H decreased significantly. The values of VC increased with the exception of methyl acetate (MA). Ethanol (Et), acetaldehyde (AA) and ethyl acetate (EA) correlated positively with decay for organic cultivated 'Camino Real'. In a general way, the MA correlated inversely with decay with the exception of conventional cultivated 'Camino Real'. Strawberries from both cultures can be stored for five days without loosing quality regardless the production system.

O ácido ascórbico, vitamina C, é usado extensivamente na indústria de alimentos, não só devido ao seu valor nutricional, mas devido a suas contribuições funcionais na qualidade do produto. Existem muitos estudos sobre a estabilidade cinética do ácido ascórbico em bebidas, mas nenhum estudo foi encontrado sobre as constantes cinéticas de degradação do ácido ascórbico adicionado em purê de pêssego. Neste trabalho, estudou-se a cinética de degradação do ácido ascórbico em purê de pêssego da cultivar Jade, em condições anaeróbicas e na faixa de 70 a 90 °C. As concentrações de purês testadas foram 12, 22 e 32 °Brix. A análise cinética dos dados sugere que a degradação foi significativamente representada pelos modelos cinéticos de zero e primeira ordem. A velocidade de degradação do ácido ascórbico foi dependente da temperatura. A energia de ativação média foi de 45 kJ.mol-1 e independente da concentração de sólidos solúveis.

Ascorbic acid (vitamin C) is extensively used in the food industry, not only for its nutritional value, but also for its many functional contributions to product quality. There have been many studies on the stability of ascorbic acid in different beverages, but no study was found on the reaction rate constants for ascorbic acid degradation in peach purée. In this work, the degradation of ascorbic acid in Jade peach purée was studied in anaerobic conditions and from 70-90 °C. The peach purée concentrations tested were 12, 22 and 32 °Brix. The kinetic analysis of the data suggests that the degradation was significantly represented by zero and first-order kinetic models. The rate of ascorbic acid degradation in peach purée was temperature dependent. The average activation energy was 45 kJ.mol-1 and independent of the concentration of soluble solids.

Testes de preferência e de aceitação foram realizados para determinar a relação entre parâmetros e atributos de qualidade de purês de pêssegos elaborados a partir das cvs. Granada, Jade, Esmeralda, Maciel, Eldorado, Jubileu, Br-6 e Magno. Pêssegos da safra 2003-2004 foram colhidos em pomar comercial na região de Pelotas - RS. As propriedades físicas e químicas foram determinadas com quatro repetições de vinte pêssegos de cada cultivar. O purê de pêssego foi elaborado por branqueamento contínuo. Os testes de preferência e aceitação foram aplicados com 50 consumidores, e as respostas dos consumidores foram registradas, respectivamente, em uma escala auto-ajustável e uma hedônica de nove pontos. Também, utilizou-se um teste descritivo com nove julgadores treinados. Analisaram-se os resultados por ANOVA, e as diferenças significativas, pelo teste de Tukey. As oito cultivares selecionadas variaram amplamente em suas características físicas e químicas. De modo geral, o teor de fenóis incrementou com o ciclo de colheita, e as cultivares Eldorado, BR-6, Jubileu e Magno foram superiores para relação SS/AT (e" 15,1), que é considerado um bom indicador para fruta de alta qualidade. Os purês elaborados com as cultivares Jubileu e Eldorado foram os preferidos pelos consumidores. O principal motivo dessa escolha foi o equilíbrio existente entre ácido e doce, que foi significativamente relacionado com SS/AT. As cultivares com baixo conteúdo de fenóis totais, quando manufaturadas, resultaram em purês de pêssegos de coloração amarela, que é uma característica desejável.

Preference and acceptance tests were performed to determine the relationship between quality parameters and attributes of peach purées from cultivars Granada, Jade, Emeralda, Maciel, Eldorado, Jubileu, Br-6 and Magno. Peaches of the crop 2003/2004 were picked from a commercial orchard in Pelotas/RS. The physical and chemical properties were determined with four replications of twenty fruit each. The peach purées were manufactured by continuous blanching. Preference and acceptance tests were performed in peach purées with 50 consumers and the consumer's response were recorded using self-adjusting and nine-point hedonic scales respectively. In addition, the descriptive test was with nine trained judges. The results were analyzed by ANOVA, and significant differences were determined using Tukey's test. The physical and chemical characteristics of the eight cultivars of peach varied widely between themselves. In general, the total phenols increased with the crop cycle. The cvs. Eldorado, BR-6, Jubileu and Magno were superiors to SS/TA ratio (e" 15.1) that is a good indicator of high-quality fruit. Peach purées of Jubileu and Eldorado were the preferred of consumers. The main reason of this choice was the balance between sweet and acid that was significantly related to SS/TA. The peach cultivars with low total phenols contents, when the fruits were manufactured, had as results a yellow coloration desirable for peach purée.