Emulsifiers: Effects on Quality of Fibre-Enriched Wheat Bread

Resistant starch (RS) is a nutritional ingredient commonly used in bread products as dietary fibre (DF). This ingredient presents similar physiological functions than those imparted by DF, promoting beneficial effects such as the reduction of cholesterol and/or glucose levels on blood. Quality improvement of bread containing RS, with an optimized combination of emulsifiers, will be useful in the development of new and healthy bakery products. The objective of this research was to analyse the effects of different emulsifiers on several quality parameters of dough and bread prepared with wheat flour partially substituted with resistant starch as a dietary fibre. A blend of wheat flour/maize-resistant starch (MRS; 87.5:12.5) with sodium chloride, ascorbic acid, α-amylase, compressed yeast and water was utilized. Emulsifiers were incorporated to formulations in different levels according to a simplex centroid design. The viscoelastic, textural and extensional properties of dough were analysed. Bread quality was evaluated throughout the gelatinization and retrogradation of starch, specific volume of loaves, and texture and firmness of bread crumb. The incorporation of 12.5% (w/w) of MRS to wheat flour caused an increase of 5% in water absorption. Stability decreases markedly (from 9.9 to 2.2 min) and the mixing tolerance index increased (from 79 to 35 UF). The sodium stearoyl lactylate (SSL)–diacetyl tartaric acid esters of monoglycerides (DATEM) mixture increased hardness and resistance to extension on dough, whilst dough containing Polysorbate 80 (PS80) was softer; nevertheless, both types of dough retained less CO2. An optimized concentration of the three emulsifiers (0.24% SSL, 0.18% PS80, 0.08% DATEM, w/w) was obtained by surface response methodology. The bread prepared with this combination of emulsifiers presented a considerable specific volume with a very soft crumb.Centro de Investigación y Desarrollo en Criotecnología de AlimentosFacultad de Ciencias Agrarias y Forestale

Study of process conditions to increase the shef-life of milk type B.

Utilizando um trocador de calor de placas, capacidade máxima de 3200 1/h, procurou-se encontrar o par temperatura-tempo mais adequado de modo a permitir uma vida de prateleira de cinco dias do leite tipo B. As temperaturas de pasteurização foram fixadas em 75°C, 80°C e 85°C, superiores as atualmente utilizadas, e os tempos de retardamento utilizados foram cerca de 11, 14, 15 e 16 segundos. Foram realizadas análises físico-químicas e microbiológicas em amostras do produto obtido nos ensaios, logo após o processamento e durante os dias de armazenamento sob refrigeração. Os resultados obtidos das análises permitem afirmar que os processamentos utilizados podem produzir um leite com os mesmos padrões físico-químicos e bacteriológicos aos de hoje comercializados, por um período de cinco dias se, mantido em refrigerador doméstico. É necessário, entretanto, uma adequação na legislação vigente que atualmente exige a presença da enzima peroxidase ativa no leite integral pasteurizado, que deve ser distribuído ao consumidor no prazo máximo de 24 (vinte e quatro) horas após a chegada do leite cru na indústria laticinista para processamento.With the use of plate heat exchanger, maximum capacity 3200 1/hour, it was tried to find the most suitable pair of pasteurizing temperature-holding time that would permit to the whole milk gets a five-day period of shelf-life. The pasteurizing temperatures were fixed about 75 °C, 80 °C and 85 °C, superiors to that used nowdays, and the holding times were fixed about 11, 14, 15 and 16 seconds. Physico-chemical and microbiological analyses were made in collecting samples of products obtained in trials, immediately after the processing and during the refrigerator-storage days. The results obtained by analyses permit to assure that processes may get a whole milk with a five-days shelf-life, it maintained in domestic refrigerator and it conserves the same actual physico-chemical and bacteriological qualities stablished by marketing. It is necessary, however, an adaptation at present Brazilian legislation which has the active peroxidase enzyme as a requirement in the pasteurized whole milk, that must be distributed for the consumer in a maximum twenty-four hours period after that the raw milk has arrived at dairy industry for processing

Use of sodium caseinate in the production of \"Minas Frescal\" cheese.

Queijo minas frescal foi produzido, em escala de laboratório, com adição de concentrado protéico de leite na forma de caseinato de cálcio. O delineamento experimental foi composto de 16 ensaios com duas variáveis (idade das culturas puras Lactococcus lactis e Lactococcus lactis ssp cremoris, variando de 1 a 4 semanas; e proporção de caseinato de cálcio em quatro níveis, 0,0%, 0,5%, 1,3% e 2,0%). Os queijos produzidos foram analisados quanto a: acidez, sólidos totais, lipídios, proteína total, cinzas e cloretos; pH e rendimento durante o armazenamento em geladeira por 8 dias. Modelos matemáticos preditivos indicaram que quanto maior é a adição de caseinato de cálcio no queijo, menor será o teor de lipídios e maior é o teor de proteína total, o que indica que a coalhada deve aprisionar na sua estrutura o caseinato de cálcio. A análise de superfície de resposta mostrou que quanto maior a proporção de caseinato de cálcio adicionada, no intervalo estudado, maior é o rendimento do queijo e este diminui com o aumento do tempo de armazenamento, ou seja, ocorre o aumento de perda de massa por causa da exsudação do soro. Testes sensoriais indicaram que não houve diferença significativa de sabor e textura, ao nível de 5%, entre os queijos produzidos.For developing, in the laboratory, a Minas Frescal cheese, Brazilian type of fresh and soft cheese, containing milk protein concentrate as calcium caseinate, it was used na experimental delineament composed of sixteen assays with two variables (age of pure cultures Lactococcus lactis and Lactococcus lactis ssp cremoris, between one and four weeks; and calcium caseinate proportion in four levels: 0,0%, 0,5%, 1,3% and 2,0%). The manufacture cheeses were analyzed concerning acidity, total solids, fat, total protein, ashes and chlorides and pH and yielding during refrigerated storing for eight days. Predictive mathematical models showed that the addition of calcium caseinate decreased fat content and increased total protein content, that is, the curdled milk has to maintain captured the calcium caseinate in its structure. The response surface analysis showed that the addition of calcium caseinate, in the studied interval, increases the cheese yielding and this decreases, as such as, storing time increases, that is, increases the loss of whey. Sensorial tests suggested that did not have statistic difference of flavor and texture, at 5% level, between manufacture cheeses

New strategies to fabricate starch/chitosan-based composites by extrusion

In this study, the impact of nanofillers on the performance of starch/chitosan composites produced by extrusion was investigated. Blends from three different proportions of starch/chitosan were produced and, for each blend, three different filler concentrations were tested. The natural -Na+ montmorillonite (Mt) and bamboo fibers were used as fillers. The composites were obtained using a twin-screw extruder from homo and nanostructured masterbatch pellets. The films were characterized concerning surface, mechanical, barrier, and thermal properties, as well as morphology and molecular changes. The results showed that the incorporation of Mt or bamboo fibers exhibited high water vapor barrier: films produced from only starch structured with 0.5 g Mt/100 g presented water vapor transmission of (4.9 ± 1.3) g/h m2, whereas films produced from starch/chitosan blend at proportion 75/25 structured with 1.0 g Mt/100 g presented (8.9 ± 0.5) g/h m2. Therefore, these materials showed competitiveness for their application to food packaging

Rheological properties of frozen concentrated orange juice (FCOJ) as a function of concentration and subzero temperatures

Data on flow properties of Frozen Concentrated Orange Juice (FCOJ) produced from oranges cv. Pera-Rio (65.04 Brix, 8.8% w/w pulp content, 2.5% w/w pectin, 3.84% citric acid, 1.293 g cm(-3)) from -18 to 0 degrees C were fitted with appropriate predictive models. The power law model was found to be the most appropriate to fit the flow curves obtained for FCOJ between 46.56 and 65.04 degrees Brix. In higher concentrations, thixotropy was observed and showed more temperature dependence. A single equation combining Arrhenius and exponential relationships was applied to describe the temperature effect and shear rate on the quantity of breakdown of FCOJ

Emulsifiers: effects on quality of Fibre-Enriched wheat bread

Resistant starch (RS) is a nutritional ingredient commonly used in bread products as dietary fibre (DF). This ingredient presents similar physiological functions than those imparted by DF, promoting beneficial effects such as the reduction of cholesterol and/or glucose levels on blood. Quality improvement of bread containing RS, with an optimized combination of emulsifiers, will be useful in the development of new and healthy bakery products. The objective of this research was to analyse the effects of different emulsifiers on several quality parameters of dough and bread prepared with wheat flour partially substituted with resistant starch as a dietary fibre. A blend of wheat flour/ maize-resistant starch (MRS; 87.5:12.5) with sodium chloride, ascorbic acid, α-amylase, compressed yeast and water was utilized. Emulsifiers were incorporated to formulations in different levels according to a simplex centroid design. The viscoelastic, textural and extensional properties of dough were analysed. Bread quality was evaluated throughout the gelatinization and retrogradation of starch, specific volume of loaves, and texture and firmness of bread crumb. The incorporation of 12.5% (w/w) of MRS to wheat flour caused an increase of 5% in water absorption. Stability decreases markedly (from 9.9 to 2.2 min) and the mixing tolerance index increased (from 79 to 35 UF). The sodium stearoyl lactylate (SSL)–diacetyl tartaric acid esters of monoglycerides (DATEM) mixture increased hardness and resistance to extension on dough, whilst dough containing Polysorbate 80 (PS80) was softer; nevertheless, both types of dough retained less CO2. An optimized concentration of the three emulsifiers (0.24% SSL, 0.18% PS80, 0.08% DATEM, w/w) was obtained by surface response methodology. The bread prepared with this combination of emulsifiers presented a considerable specific volume with a very soft crumb.Fil: Gómez, Analía Verónica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico La Plata. Centro de Investigaciones en Criotecnología de Alimentos (i); Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Agrarias y Forestales; ArgentinaFil: Buchner, Diana . Universidade de Sao Paulo; BrasilFil: Tadini, Carmen C. . Universidade de Sao Paulo; BrasilFil: Añon, Maria Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico La Plata. Centro de Investigaciones en Criotecnología de Alimentos (i); Argentina. Universidad Nacional de La Plata; ArgentinaFil: Puppo, Maria Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico La Plata. Centro de Investigaciones en Criotecnología de Alimentos (i); Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Agrarias y Forestales; Argentin

FLOW PROPERTIES AND TUBE FRICTION FACTOR OF MILK CREAM: INFLUENCE OF TEMPERATURE AND FAT CONTENT

The rheological behavior of milk cream was studied for different fat contents (0.10 to 0.31) and for a wide temperature range (2 and 87C) using a rotational rheometer. Newtonian behavior was observed, except for fat content between 0.20 and 0.31 and temperature between 2 and 33C, where viscoplastic behavior was remarkable. The rheological parameters (Newtonian viscosity, plastic viscosity and yield stress) and density were well correlated to temperature and fat content. Tube friction factor during flow of cream was experimentally obtained at various flow rates, temperatures and tube diameters (86 < Re < 2.3 x 104, 38 < Re(B) < 8.8 x 103, 1.1 x 103 < He < 6.7 x 103). The proposed correlations for density and rheological parameters were applied for the prediction of friction factor for laminar and turbulent flow of cream using well-known equations for Newtonian and viscoplastic flow. The good agreement between experimental and predicted values confirms the reliability of the proposed correlations for describing the flow behavior of cream. PRACTICAL APPLICATIONS This paper presents correlations for the calculation of density and rheological parameters (Newtonian viscosity, Bingham plastic viscosity and yield stress) of milk cream as functions of temperature (2-87C) and fat content (0.10-0.31). Because of the large temperature range, the proposed correlations are useful for process design and optimization in dairy processing. An example of practical application is presented in the text, where the correlations were applied for the prediction of friction factor for laminar and turbulent tube flow of cream using well-known equations for Newtonian and viscoplastic flow, which are summarized in the text. The comparison with experimental data obtained at various flow rates, temperatures and tube diameters showed a good agreement, which confirms the reliability of the proposed correlations.FAPESP Sao Paulo State Research Fund AgencyFAPESP[Proc. 02/02461-0

Impact of guar and xanthan gums on proofing and calorimetric parameters of frozen bread dough

The influence of guar and xanthan gum and their combined use on dough proofing rate and its calorimetric properties was investigated. Fusion enthalpy, which is related to the amount of frozen water, was influenced by frozen dough formulation and storage time; specifically gum addition reduced the fusion enthalpy in comparison to control formulation, 76.9 J/g for formulation with both gums and 81.2 J/g for control, at 28th day. Other calorimetric parameters, such as T(g) and freezable water amount, were also influenced by frozen storage time. For all formulations, proofing rate of dough after freezing, frozen storage time and thawing, decreased in comparison to non-frozen dough, indicating that the freezing process itself was more detrimental to the proofing rate than storage time. For all formulations, the mean value of proofing rate was 2.97 +/- 0.24 cm(3) min(-1) per 100 g of non-frozen dough and 2.22 +/- 0.12 cm(3) min(-1) per 100 g of frozen dough. Also the proofing rate of non-frozen dough with xanthan gum decreased significantly in relation to dough without gums and dough with only guar gum. Optical microscopy analyses showed that the gas cell production after frozen storage period was reduced, which is in agreement with the proofing rate results. (C) 2008 Elsevier Ltd. All rights reserved.CNPq (National Counsil of Technological and Scientific Development)FAPESP (The State of Sao Paulo Research Foundation)ENITIA

Convective drying of yacón: continuous measurements during drying and modeling of a highly deformable product

International audienceThis work focuses on the drying process of yacón (Smallanthus sonchifolius), source of fructooligosaccharides (FOS) and inulin, compounds proven to be prebiotics. However, depending on the conditions, these compounds can be hydrolyzed; hence, a well-controlled drying process is needed. This work aims to study the drying kinetics of yacón, considering shrinkage. The study was performed on a laboratory scale, using a magnetic suspension balance coupled to a drying oven and an image acquisition system. Several process conditions were tested, ranging from T= (50-70) °C and RH=(10-30) %. Then, the drying kinetics, critical water content, deformation, and volume loss were determined

Inactivation kinetics of polyphenol oxidase and peroxidase in green coconut water by microwave processing

The inactivation kinetics of enzymes polyphenol oxidase (PPO) and peroxidase (POD) was studied for the batch (discontinuous) microwave treatment of green coconut water. Inactivation of commercial PPO and POD added to sterile coconut water was also investigated. The complete time-temperature profiles of the experimental runs were used for determination of the kinetic parameters D-value and z-value: PPO (D(92.20 degrees C) = 52 s and z = 17.6 degrees C); POD (D(92.92 degrees C) = 16 s and z = 11.5 degrees C); PPO/sterile coconut water: (D(84.45 degrees C) = 43 s and z = 39.5 degrees C) and POD/sterile coconut water: (D(86.54 degrees C) = 20 s and z = 19.3 degrees C). All data were well fitted by a first order kinetic model. The enzymes naturally present in coconut water showed a higher resistance when compared to those added to the sterilized medium or other simulated solutions reported in the literature. The thermal inactivation of PPO and POD during microwave processing of green coconut water was significantly faster in comparison with conventional processes reported in the literature. (C) 2008 Elsevier Ltd. All rights reserved