Revista Brasileira de Produtos Agroindustriais, Campina Grande, v.6, n.2, p.115-122, 2004 115 ISSN 1517-8595 OSMOTIC DEHYDRATION OF MAPARÁ CATFISH (Hypophthalmus edentatus) FILLETS: EFFECT OF TERNARY SOLUTIONS Suezilde da Conceição Amaral Ribeiro1, Satoshi Tobinaga2 ABSTRACT A combination of dry salting and sun drying is one of the oldest and most important techniques of fish conservation in Brazil. Dried salted fish prepared by this method can easily be found in the Northern and Northeastern States. The main problem is the lack of process control, which can provoke lead to products with low microbiological and/or nutritional control. Mapará fillets were osmotically dehydrated according to a 24-1 fractional factorial design for each hypertonic solution (salt-sucrose and salt-corn syrup). The effects of the salt (12 to 14%) and sugar (30 to 40%) concentrations, temperature (30 to 50 C) and immersion time (6 to 12h) for both water loss (WL) and solids gain (SG) were evaluated. Through the obtained results, it was verified which type of solution resulted in greater water loss and smaller solids gain. In the design using sucrose and salt, only the sugar concentration wasn t significant for water loss and solids gain. All the effects were significant. In the design using corn syrup and salt. Keywords: osmotic dehydration, fish, ternary solutions DESIDRATAÇÃO OSMÓTICA DE FILÉS DE MAPARÁ (Hypophthalmus edentatus): EFEITO DE SOLUÇÕES TERNÁRIAS RESUMO A combinação de salga seca e secagem solar é uma das mais antigas e mais importantes técnicas de conservação de peixe no Brasil; o peixe salgado e seco, preparado a partir deste método, pode ser facilmente encontrado nos estados do Norte e Nordeste do país. O grande problema é a falta de controle de processo que pode levar a produtos com baixo nível nutricional e microbiológico. Filés de mapará foram osmoticamente desidratados de acordo com um planejamento fatorial fracionário 24-1, para cada solução hipertônica (sal-sacarose e sal-xarope de milho). Foram avaliados os efeitos da concentração de sal (12 to 14%) e açúcar (30 to 40%), temperatura (30 to 50 C) e tempo de imersão (6 to 12h) na perda de água (PA) e ganho de sólidos (SG) e a partir da avaliação dos resultados de cada planejamento, verificar que tipo de solução apresenta uma maior perda de água e um menor ganho de sólidos. No planejamento utilizando sal-sacarose, somente a concentração de açúcar não foi significativa para a perda de água e ganho de sólidos. No planejamento utilizando sal-xarope de milho todos os efeitos foram significativos. Palavras-chave: desidratação osmótica, peixe, soluções ternária Protocolo 573 de 02 /10 / 2004 1 Laboratório de Medidas Físicas, DEA/FEA/UNICAMP, Caixa Postal: 6121 Campinas, SP ([email protected]) 2 Laboratório de Medidas Físicas, DEA/FEA/UNICAMP, Caixa Postal: 6121 Campinas, SP ([email protected]) 116 Osmotic dehydration of mapará catfish fillets: Effect of ternary solutions. Ribeiro e Satoshi. INTRODUCTION The objective of this work was to determine the effect of ternary solutions on the A preliminary osmotic dehydration is osmotic dehydration of (Hypophthalmus often used with the objective of improving the edentatus) fillets, according to a 24-1 fractional quality of the dry food and it is not aimed a factorial design for each hypertonic solution massive water removal. This pre-treatment has (salt + sucrose and salt + corn syrup), and after a protective effect on the structure of the dried verify, which type of solution resulted in the material. The amount and rate of moisture greatest water loss and solids gain from the removal during the osmotic process depend on results of each design. some processing variables and parameters such as: type of solute and its concentration in the MATERIALS AND METHODS osmotic solution, time of immersion, temperature, etc. It was used mapará catfish species In aqueous ternary solutions which (Hypophthamus edentatus) from EDIFRIGO contain salt and sugar, the antagonistic highly localized in Santarém city in Pará state. The effects to solute gain for processed products native animals from rivers of Pará state were have been reported. Salt uptake is especially transported to Campinas city previously rinsed limited by the presence of sugar. This barrier (with chlorinated water), eviscerated, packaged effect of sugar on salt penetration was and frozen at -18 C to be transported to demonstrated for fruit and vegetable products Campinas city. (Bolin et al.,1983; Lenart & Flink, 1984) and animal products (Favetto et al., 1981; Collignan Osmotic Dehydration & Raoult-Wack, 1994; Bohuon et al., 1998). This phenomenon is due to the formation of a Filets were cut, in the frozen state, in highly concentrated sugar coating on the food flat slab geometry (0.5cm thick and 5cm product (Collignan et al., 2001). length). After cut the samples were thawed Many researchers have studied under refrigeration at 10 C for 10 hours, differents aspects of the osmotic dehydration, according Beraquet and Mori (1984). Each such as kind and concentration of the sample was individually weighted (7g) and employable solute, time and temperature of the placed in beaker with dehydration solution with process, combination of the osmotic process the same process temperature. The ratio product with other unitary operations, quality of the / solution, equal to 1/5, were chosen in order to final product, etc. (Raoult-Wack et al., 1992; avoid significant dilution of the solution during Medina, 1998; Araújo, 2000; El-Aouar, 2001). the osmotic treatment. The whole beaker- Then, the removal rate of water strongly sample was placed in a shaker (Tecnal, model depends on the parameters and variables in the 421), with agitation and temperature controls. process. Generally, the mass transference is as The slabs were taken out after predetermined high as the solute concentration, contact time, times, quickly rinsed and superficially blotted agitation and temperature. The water outcome in absorbing paper and weighed Moisture is more benefited through the use of high content was determined in a vacuum oven at temperatures than the solute insertion (Poting et 70 C for 24 hours. al., 1966; Lerici et al., 1985). Fish 1:5 weighing sample/solution Shaker drying wash weighing Figure 1 - Osmotic dehydration process Revista Brasileira de Produtos Agroindustriais, Campina Grande, v.6, n.2, p.115-122, 2004 Osmotic dehydration of mapará catfish fillets: Effect of ternary solutions. Ribeiro e Satoshi. 117 The water loss and solid gain, where calculated through the Equations (1) and (2), respectively (Hawkes and Flink, 1978). Water Loss Solid Gain MA (M MS ) MS MS WL(%) O t t 100 (1) SG(%) t O 100 (2) MA MS 0 0 MAO MSO Notation: MAo= initial water mass (g); MSo = initial solid mass (g); Mt = sample mass at time t (g); MSt = solid mass at time t (g). Experimental Design the temperature, salt and sugar concentrations, and immersion time were studied. The obtained The effect of different processing responses were water loss (WL) and solid gain conditions was determined. A 24-1 fractional (SG). Table 1 shows the levels of studied factorial design was used for each hypertonic variables. solution (salt-sucrose and salt-corn syrup) in The Statistica 5.0 (Statsoft, 1997) order to maximize water loss and minimize package was used. In order to obtain the solid gain. It was carried out a design with 11 magnitude the independent variables effects. points, where the influence of dehydration on Table 1 - Levels of studied variables in experimental design Factors -1 0 +1 Temperature ( C) 30 40 50 Salt concentration (%) 12 13 14 Sugar concentration (%) 30 35 40 Immersion time (h) 6 9 12 RESULTS AND DISCUSSION the table of the 24-1 fractional factorial experimental plan, with three central points. Table 2 shows the values for water loss The experimental data were obtained through and solids gain obtained experimentally in 11 combinations between the following osmotic dehydration of mapará fillet using independent variables: temperature, NaCl different ternary solutions of NaCl + sucrose concentration, sugar concentration, and and NaCl + corn syrup, according to data from immersion time. Table 2 - Results of weight loss, water loss and solids gain obtained experimentally through osmotic dehydration of mapará fillet Codified plan Responses T NaCl Sugar t WL (%) SG (%) WL SG (%) ( C) (%) (%) (h) Sucrose Sucrose (%)Syrup Syrup 1 -1 -1 -1 -1 12,9917 15,2146 5,5414 10,5569 2 +1 -1 -1 +1 35,6687 9,9684 28,823 7,988 3 -1 +1 -1 +1 22,7791 27,997 26,0258 19,7563 4 +1 +1 -1 -1 31,7322 10,3341 25,2804 7,6572 5 -1 -1 +1 +1 20,8249 26,9406 22,9870 21,6292 6 +1 -1 +1 -1 26,4068 6,4903 26,0286 9,3848 7 -1 +1 +1 -1 25,7329 21,4836 21,4718 19,2026 8 +1 +1 +1 +1 39,6568 12,7794 41,3967 10,1615 9 0 0 0 0 29,4467 11,7303 29,2194 17,4368 10 0 0 0 0 31,8039 12,1283 30,4286 17,0638 11 0 0 0 0 30,9992 12,7393 30,3291 17,1331 Revista Brasileira de Produtos Agroindustriais, Campina Grande, v.6, n.2, p.115-122, 2004 118 Osmotic dehydration of mapará catfish fillets: Effect of ternary solutions. Ribeiro e Satoshi. Water Loss loss, both with NaCl sucrose solution and NaCl-syrup corn solution. The results can be Tables 3 and 4 presents the magnitude more clearly visualized through the bars chart of the independent variables effects on water (Figure 1). Table 3 - Estimate effect, pure error, t coefficient and static significance, for each factor, using NaCl+sucrose solution for water loss Factors Estimate effect Pure t(2) Static significance (p) error Temperature 12,7840 0,8473 15,0887 0,0043 NaCl (%) 6,0022 0,8473 7,0843 0,0193 Sucrose (%) 2,3624 0,8473 2,7883 0,1082 Time (h) 5,5165 0,8473 6,5109 0,0228 Table 4 - Estimate effect, pure error, t coefficient, and static significance, for each factor, using de NaCl + corn syrup solution, for water loss Factors Estimate effect Pure t(2) Static significance (p) error Temperature 11,3757 0,4746 23,9665 0,0017 NaCl (%) 7,6987 0,4746 16,2197 0,0038 Syrup (%) 6,5534 0,4746 13,8068 0,0052 Tempo (h) 10,2276 0,4746 21,5477 0,0021 The aim of the fractional factorial is to significant is as high as the value of the verify the intensity of the effects and its coefficient t.