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|Type:||Artigo de evento|
|Title:||Development Of Orange Juice Freeze Drying Process|
Maciel Filho R.
|Abstract:||Freeze drying is a separation process based on sublimation phenomenon, where the solvent is removed as vapor of the frozen substance. The main advantage of this process is to obtain high quality product due to low induction of the thermal degradation. This process allows the retention of the volatilities materials responsible for flavor and may provide a rigid structure of the dried material, which is usually required. Moreover, other advantages of this process are: water low content in the dried product; no need to preserve the product in refrigerated place; reduction of the product weight and volume that facilitates the stockage and transport and increase of the product shelf life. The freeze-drying process can be used in dehydrating of foods (such as coffee, soups and fruits), pharmaceuticals and biotechnological materials. The fundamental stages involved in freeze drying process are: freezing, primary and secondary drying stages. The freezing stage represents the first separation step and the performance of the overall freeze drying process depends significantly of this stage. In the primary freezing stage, the frozen solvent is removed by sublimation. In the secondary drying stage the sublimed water is removed. In this work, the no pasteurized orange juice freeze drying process was considered, and the main objective is to develop a procedure that allows to preserve the flavor and the vitamins of the juice. The vitamin C, or ascorbic acid is one of the most important vitamins found in citric fruit juice such as orange juice. There is variation in the ascorbic acid quantity present in the orange juice due to variety, place where the fruit grows, maturity and fruit extraction method, so that the process should be tailored to couple with such variations. Brazil became the orange first world producer since 80's. The main product extracted from oranges is the juice. In addition to orange juice, various by-products such as essential oils, d'limonene and citrus pulp pellet (CPP) extraction may be obtained from orange. The choice of raw material is related to great quantity of this fruit in Brazil as well as in other regions of the world and its relatively low cost. Additionally orange juice is a well accepted and healthy product. Actually, there is a lack of data of freeze drying process for orange juice. The performance of freeze drying process is strongly dependent of the adequate operational conditions, so that is necessary extensive analysis of the effects in processing time and quality of the obtained product. In this work, the samples were carried out in freeze-dryer TELSTAR, model Cryodos-80. A drying curve was built for orange juice. A complete 24 factorial design was realized and the following variables were analyzed: thickness of the layer, freezing form, additive addition and size of particles. The effects of each variable for the studied process, as well as the interactions of variables for the determined operational range were determined. It was carried out the optimization through surface response methodology. From the obtained conditions, the freeze dried product was submitted to following analyses: water activity and Infrared humidity. These analyses were done to verify the product quality. The determination of the water activity was measured through Aqua Lab 3TE DECAGON that was maintained at 25°C. The residual water tenor contained in the sample after the drying was determined in the Infrared humidity analyzer IV 2000. It was observed that to obtain the better process performance in the considered studied range, lower thickness and small particles have to be used, because a larger interfacial area leads to a higher amount of water to be removed. It was possible to obtain a freeze-dried product with 1.1% humidity tenor and with water activity of 0.244.|
|Appears in Collections:||Unicamp - Artigos e Outros Documentos|
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