The Effects of Fermentable Dietary Fiber on Performance and Metabolism of Nile Tilapia (Oreochromis niloticus)

Abstract This study was conducted to evaluate the inclusion of new prebiotics in the diet on performance and metabolism (liver protein, glucose and glycogen) of Nile tilapia. For 60 days, 720 Nile tilapia (3.4 ± 0.60 g) were maintained in 24 polypropylene tanks (280 liters). Fish were fed with experimental diets with addition of 2.5 and 5 g kg-1 of dietary fiber of citrus pulp (DFCP), dietary fiber of linseed (DFL) and Actigen®. The experimental design was completely randomized with a 3x2 factorial arrangement. At the end of the period, there was higher final weight of tilapias fed on diets containing DFCP and DFL, and regardless of prebiotic, the best results in the final weight and length were observed for inclusion of 2.5 g kg-1. There was higher body protein deposition in tilapia fed on diets containing DFCP, without differences from those with inclusion of DFL. Total fat deposition was higher for the lowest level of inclusion (2.5 g kg-1). The digestive somatic index was higher for the diet with inclusion of DFCP, which did not differ from the diet with inclusion of Actigen®. There were higher concentrations of liver glycogen in the diets containing DFCP and Actigen®. Faced with the search for alternative growth promoters, this study confirms the possibility of using the new prebiotics (DFCP and DFL) in nutrition of Nile tilapia, because they showed efficiency equivalent to the prebiotic Actigen®.

Phosphorylated protein concentrate pumpkin seed (Cucurbita moschata): optimization by response surface methodology and nutritional characterization / Concentrado proteico fosforilado de semente de abóbora (Cucurbita moschata): otimização pela metodologia de superfície resposta e caracterização nutricional

ABSTRACT: Response surface methodology was used to determine optimum conditions for extraction of protein from pumpkin seed meal. A central composite rotational design (CCRD) including independent variables such, pH and sodium trimetaphosphate (STMP) content was used. Maximum yield was obtained at a central point of CCRD, with STMP content and pH of 4% and 4.5, respectively. These conditions resulted in protein yield of 50.04 g of soluble protein from extract/100 g pumpkin seed. The optimization of pH and STMP content allowed obtaining a product with a high protein concentration (62.56 g 100 g-1), digestibility (62.03 g 100 g-1) and concentration of essential amino acids (27.26 g 100 g-1). Regarding the polyphenols concentration, phosphorylated protein concentrate from pumpkin seed and the pumpkin seed meal presented 13.11 g 100 g-1 and 23.19 g 100 g-1, respectively. The adequacy of the model was confirmed by extracting the protein under optimum values. These results help in designing the process of optimal protein extraction from pumpkin seeds.

RESUMO: A metodologia de superfície resposta foi utilizada para determinar condições ideais para a extração de proteína da farinha de semente de abóbora. Foi utilizado um delineamento composto central rotacional (DCCR), incluindo vários níveis independentes, tais como pH e trimetafosfato de sódio (TMPS). O rendimento máximo foi obtido em um ponto central de DCCR, com conteúdo de TMPS e pH de 4% e 4,5, respectivamente. Essas condições resultaram em rendimento proteico de 50,04 g de proteína solúvel no extrato/100 g de semente de abóbora. A otimização de pH e conteúdo de TMS permitiu a obtenção de um produto com alta concentração de proteína (62,56 g 100 g-1), digestibilidade proteica (62,03 g 100 g-1) e concentração de aminoácidos essenciais (27,26 g 100 g-1). Em relação à concentração de polifenois, o concentrado proteico fosforilado de semente de abóbora e a farinha de semente de abóbora apresentaram 13,11 g 100 g-1 e 23,19 g 100 g-1, respectivamente. A adequação do modelo foi confirmada pela extração da proteína sobvalores ótimos. Estes resultados auxiliam na concepção do processo de extração ótimo da proteína de semente de abóbora.

Micronization and extrusion processing on the physicochemical properties of dietary fiber / Efeito dos processos de micronização e extrusão nas propriedades físico-químicas da fibra alimentar

ABSTRACT: Dietary fiber plays an important physiological role, which is directly linked to its physicochemical properties, water-holding, oil-binding, and cation-exchange capacities. These properties can be altered by employing enzymatic, mechanical, and physical processes. Enzymatic and chemical processes require solvents and special conditions that make it unfeasible to use. Thus, the use of physical methods, such as micronization and extrusion, make promising options to change the physicochemical properties of dietary fiber. In this way, this review aimed to approach relevant information about the use of physical processes, specifically micronization and extrusion, for this purpose. Furthermore, conceptual aspects, such as definition, classification, and properties of dietary fiber and mainly characteristics about the micronization and extrusion processes, are reported. Micronization and extrusion are based on the decrease of the particle size to a micro scale and on the combination of high temperature, mechanical shearing and pressure, respectively. Applying these methods, modifications on the food matrix occurred by increasing the surface area and disruption of the glycosidic bonds. Consequently, there is a change in physicochemical properties of dietary fiber, which predict the physiological effect associated with dietary fiber consumption, such as decrease in blood cholesterol and glucose levels and improvement of intestinal transit. Moreover, these changes increase the bio accessibility of bioactive compounds present in the food matrix and improve the antioxidant capacity of products.

RESUMO: A fibra alimentar desempenha importante papel fisiológico, o qual está diretamente ligado às suas propriedades físico-químicas de capacidade de retenção de água, ligação ao óleo e a cátions. Estas propriedades podem ser alteradas empregando-se métodos enzimáticos, químicos e físicos. Métodos enzimáticos e químicos requerem solventes e condições específicas que inviabilizam sua utilização. Assim, o emprego dos métodos físicos, tais como micronização e extrusão, tornam-se alternativas promissoras para alterar as propriedades físico-químicas da fibra alimentar. Desta forma, este trabalho visa abordar informações relevantes sobre o uso dos processos físicos, especificamente micronização e extrusão para essa finalidade. Além disso, aspectos conceituais como definição, classificação e propriedades da fibra alimentar e as principais características dos processos de micronização e extrusão são relatados. Micronização e extrusão baseiam-se na diminuição do tamanho de partícula para microescala e na combinação de alta temperatura, pressão e força de cisalhamento, respectivamente. Aplicando-se estes métodos, modificações na matriz alimentícia ocorrem pelo aumento da área superficial e rompimento das ligações glicosídicas da matriz alimentar. Consequentemente, são observadas alterações nas propriedades físico-químicas da fibra alimentar, as quais predizem o efeito fisiológico associado ao seu consumo, como diminuição dos níveis de colesterol e glicose sanguíneos e a melhora do trânsito intestinal. Ademais, essas alterações aumentam a bioacessibilidade dos compostos bioativos presentes na matéria-prima alimentícia e melhoram a capacidade antioxidante dos produtos obtidos.

Sweet potato vines in diets for growing rabbits on performance, carcass characteristics and meat quality.

The use of residues as substitutes for conventional ingredients in animal feed is a promising alternative able to reduce both costs and environmental pollution. This study aimed to evaluate the viability of using sweet potato vines (SPV) as a replacement for alfalfa hay in diets for growing rabbits. The performance, carcass characteristics, meat composition and metabolic parameters of the liver were evaluated in 30 New Zealand rabbits weaned at 35 days old and an average weight of 900 g. The animals were allotted into three dietary groups: 0SPV, control diet without SPV; 50SPV, diet with 50% replacement of alfalfa hay by SPV; 100SPV, diet with 100% replacement of alfalfa hay by SPV. The animals were slaughtered at 77 days of age. The liver was collected for analysis of glucose and hepatic glycogen and meat samples were collected for analysis of the chemical composition. The data obtained were statistically compared by analysis of variance followed by the Tukey test (0.05). None of the analyzed variables presented differences. It can be concluded, therefore, that SPV may be used as a substitute for alfalfa hay up to 100% in diets for rabbits without impairing the performance and meat composition.

Nutritional evaluation of phosphorylated pumpkin seed (Cucurbita moschata) protein concentrate in silver catfish Rhamdia quelen (Quoy and Gaimard, 1824).

An 8-week feeding trial was conducted to evaluate the effect of replacing fish meal with pumpkin seed meal (PSM) or phosphorylated protein concentrate of pumpkin seed meal (PPCPS) on growth and metabolic responses of silver catfish. Five isonitrogenous and isocaloric diets were formulated. Control diet contained fish meal as the main protein source. The treatment groups contained 25 and 50% of either PSM or PPCPS protein replaced the fishmeal protein. A total of 400 silver catfish, with initial mean weight of 24 ± 0.46 g, were distributed into 20 tanks. For data four orthogonal contrasts were applied: control diet versus PSM diets; control diets versus PPCPS diets; control versus other diets; PSM diets versus PPCPS diets. The results indicated that the fish fed PSM diets had lower weight gain when compared to either control diet or PPCPS. The PPCPS do not affect growth and protein efficiency ratio. Lower albumin contents were found for the control diet fish for the contrasts control diet versus PPCPS diet and control diet versus other diets. The hepatic ALAT enzyme activity was higher in the fish fed the control diet (P < 0.05). The hepatic ALP was most active in fish that received the PPCPS diets, when comparing control diet versus PPCPS diets and control diet versus other diets. The hepatosomatic index was higher for fish fed the PPCPS. Our results indicated that PPCPS presents relevant nutritional quality for fish and can replace the fish meal protein up to 50% without affecting growth, PER and intermediate metabolites in silver catfish.