Efeito do processo de desidratação osmótica a pulso de vácuo na transferência de massa e nas propriedades reológicas e de cor de fatias de manga

Abstract

ResumoO presente trabalho teve como objetivo estudar as propriedades reológicas, de cor e a cinética do processo de desidratação osmótica, a pulso de vácuo, de fatias de manga. As fatias de manga foram imersas em soluções hipertônicas de sacarose, nas concentrações de 45, 55 e 65 °Brix com temperatura controlada (20 e 30 °C). No início do processo, aplicou-se ou não um pulso de vácuo, utilizando as pressões de 50 e 100 mbar por 10 minutos. As frutas foram desidratadas por 5 horas, sendo avaliadas em diferentes tempos em relação à perda de peso, perda de água, ganho de sólidos, a w , cor e propriedades reológicas (tensão e deformação na ruptura). O aumento da concentração e da temperatura da solução causou um aumento na perda de peso e de água enquanto que a incorporação de solutos foi favorecida em baixas concentrações e altas temperaturas e com a aplicação do pulso de vácuo. O amaciamento do produto, caracterizado pela diminuição da tensão máxima de ruptura, e o aumento da deformação na ruptura da amostra ocorreram nas condições de maior incorporação de solutos. Não houve alteração dos parâmetros de cor das mangas durante o processo de desidratação. Palavras-chave: Tommy Atkins; tensão na ruptura; deformação na ruptura; conservação; cinética; croma. AbstractThe aim of this work was to study rheological and colour properties and process kinetics of mango slices subject to pulsed vacuum osmotic dehydration. The slices were immersed in osmotic sucrose solutions (45, 55 and 65 °Brix) at 20 or 30 °C. At the beginning, a sub-atmospheric pressure was applied or not to the solid-liquid system (50 or 100 mbar of pressure) for 10 minutes followed by an atmospheric pressure operation up to 5 hours. Fruit samples were evaluated after pre-determined times in terms of weight loss, water loss, solids gain, a w , colour and rheological properties (stress and strain at rupture). The concentration and temperature increases lead to a weight and water reduction. Solid gain was favoured by lower concentration and a higher temperature and by the pulsed vacuum application. The sample softening, which is characterized by a reduction of maximum stress at rupture, and the increased stress on strain at rupture ocurred at the great solids updake conditions. The colour parameters did not change during the dehydration process.

Physicochemical characteristics of guava “Paluma” submitted to osmotic dehydration

“…It was possible to verify that the Chroma of OD fruit ( Figure 5) has been positively affected by osmotic dehydration, reaching a maximum value around 23, between the 12 and the 15 th day of storage, proving, therefore, the red color tendency towards darkening, due to osmotic treatment. These results are similar to those reported by Pereira et al (2006), who evaluated the color of papaya dehydrated in sucrose solutions, and they are also similar to those obtained by Ito et al (2007), who studied the effect of osmotic dehydration upon mango color parameters. The process of osmotic dehydration utilized to preserve minimally processed guavas, associated to package and refrigeration, suggests effectiveness, since it slows the process of senescence and inhibits the respiratory metabolism of the product, thus providing maintenance of the physicochemical quality and increasing shelf life of the product.…”

“…Osmotic dehydration process (OD) has been considered an important tool for preservation of tropical fruit and development of new fruit products. The OD process has been used as a pretreatment to the traditional processes of drying and freezing (FALADE et al, 2007;LOMBARD et al, 2008) and also to produce minimally processed products (CASTELLO et al, 2009;TORRES et al, 2008).…”

Selection of mango rosa genotypes in a breeding population using the multivariate-biplot method

“…Mango fruits are sources of fiber and vitamins such as vitamin C and provitamin A (beta-carotene). However, these fruits are little commercialized in the world, and most of this production is consumed in domestic markets (ITO et al, 2012 Mid-North portion of the Northeast region in Brazil. Their fruits show attractive size, skin and pulp color and smell, thin skin, high sugar content (fructose), intermediate pulp fiber content, and low occurrence of internal collapse (pulp deterioration due to nutritional imbalance between calcium and nitrogen, relative to the Tommy Atkins mango).…”

Influence of the process parameters on osmotic dehydration of mapara (Hypophthalmus edentatus) fillet

“…In general, osmotic dehydration is carried out at atmospheric pressure, however, several authors have assessed the effect of sub-atmospheric pressures (vacuum) as an alternative to increase the mass transfer rates and decrease the process temperature, which may guarantee better product quality (Barat et al 2001;Mújica-Paz et al 2002;Panadés et al 2006;Ito et al 2007;Occhino et al 2011).…”