Rui Sérgio dos Santos Ferreira da Silva

Response surface methodology for extraction optimization of pigeon pea protein.

Abstract Optimisation for pigeon pea protein extraction (Y) (Cajanus cajan (L) Millsp from the new IAPAR 43-Arata variety) was investigated using response surface methodology. A compound central design was used with variables (X1) NaCl concentration (0.000; 0.025; 0.050; 0.075 and 0.100M); (X2) pH (2.5; 4.0; 5.5; 7.0 and 8.5) and (X3) liquid:solid ratio (5:1; 10:1; 15:1; 20:1; and 25:1, v/w). A model of the second degree equation was used to create the surface responses and confirmative studies were carried out. The following equation: Y =−19.3733+8.6004x2−0.508526x22 shows optimum conditions for protein extraction of about 75% yield, at pH 8.5 without NaCl regardless of the liquid:solid ratio (v/w) under the experimental conditions studied.

Formulation and evaluation of dry dessert mix containing sweetener combinations using mixture response methodology.

Abstract Reduced calorie foods are an important area for product development. Foods formulated for diabetics and/or weight reduction tend to replace bulk caloric sweeteners with high intensity sweeteners. A mixture experimental design was used to model the acceptability of a low calorie dessert mix sweetened with single, binary and tertiary combinations of saccharin, cyclamate and stevioside. The design included constraints to permit sweetener addition according to the limits of food laws. The dessert mixture had a 37% caloric reduction when compared to the sucrose sweetened pudding, and texture equivalent to commercial products was reproduced with the addition of 0.01 g/100 ml carrageenan. The most acceptable combination of the sweeteners tested was saccharin: cyclamate (0.755:0.245), but other combinations could be used to obtain an acceptable product taking cost of the ingredients into consideration. ©

Influence of carbon source and the fermentation process on levan production by Zymomonas mobilis analyzed by the surface response method.

3) was used to analyze the effects of the type and concentration of the substrate, as well as the batch and fed batch processes. A complete second factorial design (2 2 ) was used to observe the importance of sugar cane juice. The results indicated that the batch process improved the levan production reaching 40.14 g/L. The addition of sugar cane juice was not statistically significant for levan formation, however sugar cane juice stimulated biomass, sorbitol and ethanol production. The best medium for levan production was 150 g/L sucrose in batch.

Stability of unpasteurized and refrigerated orange juice

The stability of orange juice obtained from a small extractor and stored in a polyethylene bottle was assessed under isothermal and non-isothermal storage conditions at 4, 8 and 12oC for 72 hours. pH, titratable acidity and Brix did not alter significantly during the 72 hours storage. Microbiological analysis showed high initial count for moulds and yeasts that increased in the juice stored for 72h under the non-isothermal conditions with temperature abuse (12oC/4h). Date of the sensory evaluation showed a small reduction in product acceptance in this condition. The juice, in the recommended validity period (48h), presented losses of less than 20% of the initial ascorbic acid content regardless of the treatment. However, after this time, the degradation became accentuated reaching, at 72h storage, retentions of 72 to 85%.

Simulation of NaCl and KCl mass transfer during salting of Prato cheese in brine with agitation: a numerical solution

The association of dietary NaCl with arterial hypertension has led to a reduction in the levels of this salt in cheeses. For salting, KCl has been used as a partial substitute for NaCl, which cannot be completely substituted without affecting product acceptability. In this study a sensorially adequate saline solution (NaCl/KCl) was simultaneously diffused during salting of Prato cheese in brine with agitation. The simultaneous multicomponent diffusion during the process was modeled with Ficks second generalized law. The system of partial differential equations formed was solved by the finite element method (FEM). In the experimental data concentration the deviation for NaCl was of 7.3% and for KCl of 5.4%, both of which were considered acceptable. The simulation of salt diffusion will allow control and modulation of salt content in Prato cheese, permitting the prediction of final content from initial conditions.

The production of sorbitol by permeabilized and immobilized cells of Z. mobilis in sucrose

The production of sorbitol by permeabilized and immobilized cells of Zymomonas mobilis in Luffa cylindrica was investigated in sucrose medium. A full 23 factorial design was used to verify the influence of each factor and its interactions. The cell permeabilization showed a significant and negative effect upon the production of sorbitol, while the time of cultivation and the immobilization process were significant and positive. The results demonstrated that the cell immobilization and the time of cultivation of 36 h presented higher production of sorbitol.

Optimized Neural Network for Instant Coffee Classification through an Electronic Nose

Flavor is one of the most important features of food, especially of coffee. The evaluation of this sensory feature is complex yet indispensable in quality control of instant coffees. In this work, an artificial neural network (ANN) was developed for instant coffee classification based on an electronic nose (EN) aroma profile. To this purpose, a hybrid algorithm was developed, containing: bootstrap resample methodology; factorial design and sequential simplex optimization to tune network parameters; an ensemble multilayer perceptron (MLP) trained with backpropagation for coffee classification; and causal index procedure for knowledge extraction from the trained ANN. The produced neural network classifier correctly recognizes 100% of coffees studied. Furthermore, the causal index employment allowed inference of some rules on how the coffees were separated according to the sensors available in EN. The results indicate that the applied methodology is a promising tool for instant coffee quality control.

Queijo tipo minas frescal com derivados de soja: características físicas, químicas e sensoriais

Nove provadores selecionados e treinados avaliaram a aparencia, aroma, sabor e textura de tres formulacoes de queijo tipo minas frescal (tradicional, com extrato hidrossoluvel de soja em po (PS-60) e coalho bovino e com PS-60 e coagulante microbiano). O queijo tradicional caracterizou-se pela aparencia de umidade e de sabor coalhada. O queijo com PS-60 elaborado com coalho bovino apresentou cor creme e gosto amargo e a amostra com coagulante microbiano mostrou maior aroma soja. As caracterizacoes instrumentais das tres formulacoes de queijo foram desenvolvidas atraves da analise do perfil de textura (TPA) utilizando um texturometro TA-XT2i Stable Micro System e, para a analise de cor, utilizou-se um aplicativo computacional e escâner. Com relacao a textura, o queijo minas frescal tradicional e o queijo produzido com PS-60 e coalho bovino caracterizaram-se mais duros; o queijo tradicional apresentou maiores valores nos parâmetros de fraturabilidade, coesividade e mastigabilidade e os queijos tradicional e aquele formulado com PS-60 e coagulante microbiano -apresentaram-se mais elasticos. Em relacao a cor, o queijo tradicional apresentou cor branca amarelo-esverdeada mais intensa. A aceitacao das amostras foi avaliada por cem provadores nao treinados, utilizando-se escala hedonica estruturada de sete pontos. Os queijos formulados com PS-60 apresentaram 88% de aceitacao.

Dietary vitamin E supplementation on cholesterol and cholesterol oxides of pig meat and cooked ham

O objetivo deste trabalho foi avaliar o efeito protetor da vitamina E no presunto cozido. Noventa e seis suinos (LW X L X P), 48 machos castrados e 48 femeas foram divididos aleatoriamente em 4 blocos. Cada bloco recebeu 4 tratamentos: dieta controle, dietas formuladas com 100 mg, com 200 mg e com 400 mg de vitamina E/kg de racao. O periodo de fornecimento da dieta foi de 116 dias antes do abate, quando os suinos atingiram uma media de peso de 110 kg. O presunto cozido foi produzido em um frigorifico, e estocado a 5,0 ± 0,2°C para as analises quimicas. Analise de colesterol e oxidos de colesterol foram feitas em amostras de presunto cozido com 0, 30 e 60 dias de armazenamento. O colesterol e os oxidos de colesterol foram determinados por cromatografia liquida. A media para os niveis de colesterol foi de 46,53 ± 0,47 mg/100g. Entretanto, foi observada uma reducao de 30% nos niveis de colesterol das amostras que receberam suplementacao de 400 mg de vitamina E/kg. Durante o armazenamento do presunto cozido foi observado uma reducao nos niveis de colesterol, associada a um aumento nos niveis de oxido de colesterol. Os oxidos de colesterol observados foram: cholesta-4,6-dien-3-one; 20a-hydroxycolesterol; 24-hydroxycholesterol e 25-hidroxycholesterol. Niveis de suplementacao de 200 mg de vitamina E/kg ou mais, fornecidos durante 116 dias antes do abate, mantiveram os teores de oxidos de colesterol abaixo de 10 µg/g.

Cinética de inativação de inibidores de tripsina e de insolubilização de proteínas de diferentes cultivares de soja

Soybean (Glycine max (L.) Merrill) is one of the most studied vegetables, due to its use as sources of edible oil and protein for human and animal feeding. The presence of trypsin inhibitors in soy grain restrict its utilization and requires heating to improve the nutritional quality. However, excessive heating may reduce the protein quality. Soybean cultivar BR-36 containing normal content of trypsin inhibitors and soybean cultivars (BRM 95 5297 and BRM 95 5262) with low content of trypsin inhibitors were used. Soybean flour with 10 and 16% moisture were heated at 95°C in five different retention times ( 15, 25, 50, 75 and 100 min) and, then, the respective kinetic inactivation parameters for the trypsin inhibitors and protein insolubilization were estimated. By the first-order reaction for inactivation of trypsin inhibitor and protein insolubilization, the rate constant of trypsin inhibitor reaction incresead, resulting in decreasing heating time of BRM 95-5297 and BRM 95-5262 cultivars when compared to BR-36 cultivar. The increase of 6% moisture in flours also increased the rate constant of reaction for inactivation of trypsin inhibitors and for protein insolubilization.