Abstract This research aimed at studying the effects of different washing conditions (distilled water x distilled water + NaHCO3 + NaCl) and cryoprotectants (NaCl + saccharose x sorbitol + sodium tripolyphosphate) for the production of tilapia surimi. The experiment used a factorial design 2 x 2 and the variables analyzed were proximate composition, non-nitrogen protein (NNP) removal, texture, color and yield. The protein and moisture contents of the surimi were influenced neither by washings nor by cryoprotectants, while the ash content was higher when NaCl + saccharose were used as the cryoprotectants and the yield was higher when only distilled water was used for the washings. Combining distilled water for the washings and NaCl + saccharose as the cryoprotectants provided the highest lipid and NNP removals. The different treatments produced surimi gels with similar colors and texture.

Resumo O objetivo deste estudo foi avaliar o efeito de temperaturas de desidratação por atomização sobre o rendimento e as características microbiológicas, físicas e químicas de claras de ovos em pó. Os tratamentos utilizados no experimento foram 90 °C, 120 °C e 150 °C, contando com cinco repetições. O rendimento foi determinado pela relação entre os pesos da clara desidratada e in natura. As claras em pó foram analisadas quanto a umidade, proteínas, lipídeos, cinzas, estafilococos coagulase-positiva, Salmonella spp e coliformes a 45 °C. A análise da cor foi feita no sistema Lab e o ΔE foi calculado a partir desses valores. Os resultados foram submetidos à análise de variância e as médias foram comparadas pelo teste de Tukey, utilizando-se nível de significância de 5%. A temperatura de secagem influenciou a umidade das claras desidratadas mas não interferiu nos teores de proteínas, lipídeos e cinzas e nas características microbiológicas. A secagem a 150 ºC proporcionou maior rendimento mas provocou escurecimento e aumento na intensidade do tom amarelo das claras desidratadas.

Abstract The aim of this study was to evaluate the yield, microbiological, physical, and chemical characteristics of powdered egg white obtained by spray drying at different temperatures. The spray drying air temperatures were 90 °C, 120 °C, and 150 °C, with five repetitions of each treatment. Yield rate was calculated by the ratio between powdered egg white and fresh egg white. The powdered egg whites were analyzed regarding moisture, protein, lipids, ash, coagulase-positive staphylococci, Salmonella spp, and coliforms at 45 °C. Color analysis was performed with the Lab space and ΔE was calculated from these values. The data were subjected to analysis of variance and Tukeys test at 5% significance. The spray drying air temperature affected the moisture of the powdered egg whites, without influencing the concentrations of proteins, lipids, and ash, nor the microbiological analyzes. The drying at 150 °C provided higher yield rate, but caused the darkening and the increase in the yellowness of the powdered egg white.

RESUMO: O objetivo deste trabalho foi avaliar o curso da rancidez oxidativa em rações de tilápia do Nilo contendo biomassa bacteriana de Rubrivivax gelatinosus . Foram aplicados seis tratamentos experimentais constituídos de ração basal (controle negativo), ração basal contendo astaxantina (controle positivo) e ração basal contendo quatro concentrações da biomassa bacteriana. As análises de ácido tiobarbitúrico para estimar a rancidez foram realizadas após 6 e 12 meses de armazenamento das rações. Concluiu-se que a biomassa de R. gelatinosus foi capaz de reduzir a rancidez da ração de peixes em 32,52 a 44,72% após 6 meses de armazenamento e em 37,85 a 52,37% após 12 meses de estocagem.

ABSTRACT: The purpose of this research was to investigate the progress of the rancidity in Nile tilapia diets containing bacterial biomass of Rubrivivax gelatinosus . Six experimental treatments comprised basal diet (negative control), diet with asthaxanthin (positive control) and 4 diets with different concentrations of the bacterial biomass. The thiobarbituric acid assay for rancidity analyses were accomplished after 6 and 12 months of diets storage. It was concluded that Rubrivivax gelatinosus biomass minimized the racidity in Nile tilapia diets in 32.52 to 44.72% at 6 months and in 37.85 to 52.37% at 12 months of storage.