Desenvolvimento de misturas liofilizadas para croquete de tilápia do Nilo

• Autor(a) principal: Fuchs, Renata Hernandez Barros
• Data de Publicação: 2013
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Repositório Institucional da Universidade Estadual de Maringá (RI-UEM)
• Texto Completo: http://repositorio.uem.br:8080/jspui/handle/1/1427
• topic: Tilápia do Nilo; Misturas liofilizadas; Carne mecanicamente separada CMS; Algoritmo genético; Farinha de linhaça; Ômega-3; Brasil.; Nile tilapia; Mechanically separated meat; Genetic algorithm; Flaxseed flour; Omega-3; Brazil.; Ciências Agrárias; Ciência e Tecnologia de Alimentos

The Nile tilapia (Oreochromis niloticus) is a fish whose production is growing worldwide. It has mild flavor, low fat and high acceptability, being consumed mainly in the form of fillets. However, this cut represents only 30-35% of the live weight of the fish. The meat which is adhered to fish carcass after filleting process may be removed and used in the development of new food products. This meat is called mechanically separated meat (MSM) or tilapia mince. The objective of this study was to use the MSM of Nile tilapia in developing freeze-dried mixtures of fish croquette, enrich it with flaxseed flour to increase your omega-3 content and evaluate the chemical, microbiological and sensory stability for 240 days. Cost, fiber content and sensory analysis of flavor, texture and overall acceptance of seven formulations of tilapia croquette were evaluated, varying levels of wheat, oats and rye used in its production. A genetic algorithm (GA) with desirability functions was combined with a multiobjective optimization of the response surface models. The optimized mixture, called basic formulation was freeze-dried until a constant value for water activity (aw) was obtained. Through a preference ranking test (p <0.05), it was determined the higher content of flaxseed flour can be added to the basic formulation, with no changes to the basic formulations and the enriched one. The two formulations, raw and deep fried in soybean oil had their proximal composition and fatty acid composition determined. Indices of nutritional quality of lipids from the basic and enriched formulations (raw and deep fried) were also evaluated. The parameters evaluated were index of atherogenicity (AI), index of thrombogenicity (IT) and ratio HH (hypocholesterolemic fatty acids/ hypercholesterolemic fatty acids). The freeze-dried samples of mixtures of tilapia croquete were vacuum packed in transparent plastic bags with a thickness of 180? and stored in dark plastic boxes at room temperature (24oC ± 3oC). The stability of both formulations were evaluated through analysis of TBARS and aw (on days 0, 30, 60, 90, 120, 150, 180, 210 and 240), total and fecal coliforms, Staphylococcus coagulase positive, molds and yeasts, Bacillus cereus and Salmonella sp (on days 0, 120 and 240) and sensory acceptance of the attributes appearance, texture, odor, flavor and overall acceptance (on days 0, 210 and 240), using 9-point hedonic scale. The combination of flours was chosen to minimize the cost and maximize the overall acceptance and fiber content. The overall acceptance showed a statistically significant correlation (p?0.05) with flavor (r=0.67) and texture (r=0.61). The GA-based approach indicated that the highest overall acceptability is obtained when using wheat and rye flours in equal parts. This formulation had an overall acceptance of 7.52, fiber content of 11.50 g kg-1 and cost of $ 2.21/ kg. After 24 hours of freeze-drying the water activity of the mixture was 0.11. The ranking preference test indicated that the limit of addition of flaxseed flour is 12.5 g 100 g-1. In addition to the enhanced content of omega-3, the enriched formulation showed a lower loss of this substance during frying and better indices of nutritional quality of lipid than the basic product. The water activity of mixtures increased significantly (p <0.05) ranging between 0.1666 and 0.5392 (control mixture) and between 0.0554 and 0.5415 (enriched misture). TBARS values were increased significantly (p<0.05), from 0.08 to 0.38 mg MDA kg-1 (control mixture) and 0.11 to 0.40 mg MDA kg-1 (enriched mixture). The attributes appearance, texture and overall acceptance of the control mixture remained constant and flavor was improved during storage. During the evaluation period, the enriched mixture did not change the acceptance of its sensory attributes (p<0.05). After 120 days of storage, the control mixture showed significantly higher overall acceptance than the averages of the enriched mixture. At the end of the evaluation, the overall acceptance was approximately 8 for control mixture and 6 for the enriched mixture. Microbiological parameters did not exceed the limits allowed for consumption. The use of genetic algorithm was a suitable tool in the optimization process of the basic formulation of tilapia croquette and freeze-drying contributed to the development of a product with high added value, high quality and stability. The enrichment of the basic formulation with flaxseed flour increased its nutritional value, with a high content of omega-3 fatty acids and improved IA, IT and HH ratio, even when this product is subjected to deep fat frying. Control and enriched freeze-dried mixtures of tilapia croquette remained suitable for consumption during 240 days of storage.