Utilização de ultrassom na conservação de suco de laranja : efeito sobre características físico-químicas, enzimáticas, microbiológicas e sensoriais
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Data
2014-02-24
Autores
Schuina, Guilherme Lorencini
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Universidade Federal do Espírito Santo
Resumo
Consumption of fruit juice is increasing in Brazil. Between 2002 and 2009 the consumption of juice, whether concentrated, powder, juices and nectars, increased by 21 %. This occurs because of its pleasant taste and because the juice is considered to be healthy and a great source of vitamin C. Orange juice is the most common juice manufactured by beverage processing industry. Several factors may affect the quality of orange juice. Pectin methyl esterase (PME) is the main enzyme that cause changes in orange juice. Pasteurization and commercial sterilization are the most common preservation methods used to inactivate enzymes and microorganisms, but they can cause adverse effects in relation to the sensory characteristics (color, flavor) of the products. The ultrasound technology has recently been studied as a way to preserve food without causing adverse effects caused by heat treatments. The objective of this study is to evaluate the use of sonication and thermosonication, as a way to conserve orange juice. For this, it was measured the mesophilic and yeast count, the activity of pectin methyl esterase , the content of vitamin C , color , pH, soluble solids and the cloudy value. The sensory acceptance of orange juice subjected to thermosonication was also analyzed. The results obtained were compared with those obtained by natural juice and pasteurized juice. An ultrasound of 40 kHz , associated temperatures of 25 º C, 30 º C, 40 º C, 50 º C and 60 º C for 10 min . Treatments using ultrasound at 50 º C and 60 ° C were able to reduce the yeasts and mesophilic count in 3 log cycles. Same result was found when the heat treatment at 90 ° C for 30 seconds was used. It was observed that the application of thermosonication promotes a substantial reduction in the activity of pectin methyl esterase and has a minor loss of vitamin C. The treatment with better reduction in the activity of PME was the one of 40 kHz ultrasound with temperature of 60 º C. In relation to the ascorbic acid retention, the lower the temperature used in conjunction with sonication, the lower the loss of this compound was observed. The content of soluble solids, pH and color of the juice has not changed throughout the process. When evaluating the acceptability of the juice, it was found that the color was not affected by any treatment. The aroma, flavor and overall acceptance of juice obtained by thermosonication had higher sensory scores in comparison with sensory scores of the pasteurized juice. The thermosonication treatment is considered a potential alternative method of food preservation
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Thermosonication , Preservation of juice , Quality of juice , Termossonicação