Optimization of the osmotic dehydration of ginger/Otimizacao da desidratacao osmotica do gengibre

The present research aimed to optimize the process of osmotic dehydration (OD) of ginger with hypertonic sucrose solution employing response surface methodology. A 23 experimental planning was carried out and 17 experimental assays were performed based on three independent variables (temperature, concentration of the osmotic solution and immersion time) and three dependent variables (moisture loss (ML), solids gain (SG) and dehydration efficiency index (DEI)). The selected assay conditions exhibited the preferred DEI value (the highest ML and lower SG), which were considered in the optimization. Assay 16 demonstrated to be the most favorable conditions for the osmotic dehydration of ginger (DEI =1.61) at 40 40[degrees]C, 50[degrees]Brix and 90 minutes of immersion time. Assay 1 performed at 34[degrees]C, 44[degrees]Brix and 120 minutes of immersion time also displayed desirable response (DEI =1.45). Thus, these two assays were evaluated for the presence of thermal-tolerant coliforms: Bacillus cereus and Salmonella sp.. The analyses presented values below the acceptable limits, which assured high quality hygienic and sanitary conditions of the product. Key words: Zingiber officinale Roscoe, water loss, microbiological analysis. A presente pesquisa teve como objetivo otimizar o processo de desidratacao osmotica (DO) do gengibre, com solucao hipertonica de sacarose, pelo metodo de superficie de resposta. Foi utilizado um planejamento fatorial 23 completo, totalizando 17 ensaios, tendo como variaveis independentes: temperatura, concentracao da solucao osmotica e tempo de imersao e variaveis dependentes, como, : perda de umidade (PU), ganho de solidos (GS) e indice de eficiencia de desidratacao osmotica (IED). Para otimizar foi considerado o melhor ensaio, o que obteve maior IED, ou seja, maior PU e menor GS. As melhores condicoes para a desidratacao osmotica de gengibre foram obtidos a 40[degrees]C, 50[degrees]Brix e 90 minutos de imersao (Ensaio 16) com IED de 1.61 vindo em seguida o Ensaio 1 (34[degrees]C, 44 0Brix e 120 minutos de imersao) com IED de 1.45. Estes ensaios foram avaliados quanto a coliformes tolerantes termicas, Bacillus cereus e Salmonella spp., apresentando valores abaixo dos limites aceitaveis, indicando boas condicoes higienicas sanitarias do produto. Palavras-chave: Zingiber officinale, perda de agua, analise microbiologica.