Modulation of the physico-chemical and functional properties of bread by applying surface treatments

El pan es un alimento de gran consumo desde la antigüedad, obtenido de un proceso de panificación dinámico. Una de las innovaciones de mayor éxito en panificación ha sido el pan parcialmente cocido obtenido por la tecnología de panificación interrumpida que proporciona pan crujiente en cualquier momento del día. La crujibilidad es el atributo más demandado por los consumidores en el pan crujiente fresco. Desafortunadamente, la crujibilidad es percibida por corto tiempo después del horneado y la pérdida de ésta es uno de los atributos que causa rechazo en los consumidores. El objetivo de esta investigación fue la modulación de las propiedades físico-químicas y funcionales del pan mediante la aplicación de tratamientos de superficie con el fin de comprender las características de la corteza y el desarrollo de productos de pan con un valor agregado. Para abordar dicho objetivo se han realizado estudios para determinar el impacto de la adición de vapor, durante el horneado, sobre las propiedades mecánicas de la corteza y para evaluar la influencia de estas propiedades en los parámetros de calidad utilizando diferentes panes comerciales. Además se han realizado estudios para modular las propiedades de la corteza dirigidos a entender su microestructura y modificarla mediante tratamientos enzimáticos con amiloglucosidasa o con un recubrimiento funcional, con la finalidad de modificar la permeabilidad de la corteza u obtener panes probióticos. Los resultados mostraron que la cantidad de vapor utilizada durante la cocción (100, 200 y 400 ml) modificaron las propiedades físico-químicas y mecánicas así como la estructura de la corteza del pan. Los parámetros de calidad permitieron la diferenciación de variedades de pan parcialmente cocido, específicamente las propiedades mecánicas de la corteza junto con el volumen específico, dureza y estructura de la miga. Sin embargo, la textura de la corteza de pan fue significativamente dependiente de las condiciones de ensayo (velocidad y sección de la sonda). Los resultados mostraron que la velocidad más baja (0,5 mm / s) dio información acerca de la estructura celular de la corteza relacionada con la textura crujiente. Por otra parte, la estructura celular fue modificada por la amiloglucosidasa pulverizada sobre la superficie del pan antes de la cocción, lo que condujo a una disminución en el contenido de agua y actividad del agua de la corteza, lo cual se requiere para extender crujibilidad. La aplicación de recubrimientos comestibles con L. acidophilus microencapsulado sobre la superficie pan (disperso o en multicapa) garantizó la supervivencia del microorganismo después del tiempo de cocción y almacenamiento, a pesar de que estos disminuyeron la fuerza de fractura y actividad de agua de la corteza. El análisis de microestructura demostró la presencia de microcapsulas dispersas en la corteza de pan. Por lo tanto, L. acidophilus incluido en microcápsulas pueden ser incorporado en la superficie de pan a través de recubrimientos comestibles, abriendo la posibilidad de obtener panes funcionales.Altamirano Fortoul, RDC. (2013). Modulation of the physico-chemical and functional properties of bread by applying surface treatments [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/33398TESI

Effect of high pressure processing on wheat dough and bread characteristics

8 pages, 3 figures, 4 tables.-- Available online 30 June 2009.Microbial, physical and structural changes in high pressured wheat dough were studied as a function of pressure level (50–250 MPa) and holding time (1–4 min). Thereafter, selected conditions of high hydrostatic processing (HPP) were applied to bread dough and the technological quality of the obtained breads was studied. The effect of HPP on wheat dough was investigated by determining microbial population (total aerobic mesophilic bacteria, moulds and yeasts), color and mechanical and texture surface related dough parameters (cohesiveness, adhesiveness, hardness and stickiness). HPP reduced the endogenous microbial population of wheat dough from 10^4 colony forming units/g (CFU) to levels of 10^2 CFU. HPP treatment significantly (P < 0.05) increased dough hardness and adhesiveness, whereas treatment time reduced its stickiness. Scanning electron micrographs suggested that proteins were affected when subjected to pressure levels higher than 50 MPa, but starch modification required higher pressure levels. HPP treated yeasted doughs led to wheat breads with different appearance and technological characteristics; crumb acquired brownish color and heterogeneous cell gas distribution with increased hardness due to new crumb structure. This study suggests that high hydrostatic processing in the range 50–200 MPa could be an alternative technique for obtaining novel textured cereal based products.This work was financially supported by Spanish Ministerio de Ciencia e Innovación Project (AGL2005-05192-C04-01), Consejo Superior de Investigaciones Científicas (CSIC) and Mexican Consejo Nacional de Ciencia y Tecnología (CONACYT).Peer reviewe

Viability of some probiotic coatings in bread and its effect on the crust mechanical properties

9 pages, 4 figures, 3 tablesThe objective of this study was to obtain functional bread combining the microencapsulation of Lactobacillus acidophilus and starch based coatings. Different probiotic coatings (dispersed or multilayer) were applied onto the surface of partially baked breads. In all treatments, microencapsulated L.acidophilus survived after baking and storage time, although reduction was higher in the sandwich treatment (starch solution/sprayed microcapsules/starch solution). Despite coatings significantly affected the physicochemical properties of the crust, increasing water activity and reducing the failure force, the sensory evaluation revealed a good acceptability of the functional breads. Scanning electron microscopy revealed the presence of scattered microcapsules onto the bread crust, being highly covered in the sandwich coating. Therefore, L.acidophilus included in microcapsules can be incorporated to bread surface through edible coatings, leading functional bread with similar characteristics to common bread, but with additional healthy benefits.Authors acknowledge the financial support of Spanish Ministry of Economy and Sustainability (Project AGL2011-23802) and the Consejo Superior de Investigaciones Científicas (CSIC). Authors thank Mr. Alfonso Martínez from CICATA, IPM (México) for his contribution with the electron microscopy analysis. R. Altamirano-Fortoul would like to thank her PhD grant (JAE pre) to CSIC. The authors also thank Forns Valencians S.A. (Spain) for supplying commercial frozen partially baked breads.Peer reviewe

Probiotic edible films as a new strategy for developing functional bakery products: the case of pan bread

In the present paper, a novel approach for the development of probiotic baked cereal products is presented. Probiotic pan bread constructed by the application of film forming solutions based either on individual hydrogels e.g. 1% w/w sodium alginate (ALG) or binary blends of 0.5% w/w sodium alginate and 2% whey protein concentrate (ALG/WPC) containing Lactobacillus rhamnosus GG, followed by an air drying step at 60 °C for 10 min or 180 °C for min were produced. No visual differences between the bread crust surface of control and probiotic bread were observed. Microstructural analysis of bread crust revealed the formation of thicker films in the case of ALG/WPC. The presence of WPC improved significantly the viability of L. rhamnosus GG throughout air drying and room temperature storage. During storage there was a significant reduction in L. rhamnosus GG viability during the first 24 h, viable count losses were low during the subsequent 2–3 days of storage and growth was observed upon the last days of storage (day 4–7). The use of film forming solutions based exclusive on sodium alginate improved the viability of L. rhamnosus GG under simulated gastro-intestinal conditions, and there was no impact of the bread crust matrix on inactivation rates. The presence of the probiotic edible films did not modify cause major shifts in the mechanistic pathway of bread staling – as shown by physicochemical, thermal, texture and headspace analysis. Based on our calculations, an individual 30–40 g bread slice can deliver approx. 7.57–8.98 and 6.55–6.91 log cfu/portion before and after in-vitro digestion, meeting the WHO recommended required viable cell counts for probiotic bacteria to be delivered to the human host

Mechanical, microstructure and permeability properties of a model bread crust: Effect of different food additives

The aim of this study was to understand the action of different additives on the crust properties using a layer crust as a model. Moisture content, water vapor barrier properties, water sorption isotherms and mechanical properties were evaluated. Crust model showed multilayer internal structure. Glycerol (10% and 20%) and HPMC-10% increased moisture content, whereas linolenic acid and beeswax, glycerol-1%, HPMC-0.5% and citric acid significantly decreased it. Water vapor permeability (WVP) decreased with lipids and citric acid, due to their hydrophobic nature and crosslinking action, respectively. Hydrophobic additives lowered the WVP of the crust and provided water barrier properties and brittle texture. Crust mechanical properties were greatly correlated with water present as well as with composition of crust layer. Barrier properties of the crust layer were greatly dependent on the hydrophilicity or hydrophobicity of the additives, which determined the internal interactions between starch and proteins and the microstructure and mechanical properties.The authors acknowledge the financial support of Spanish Scientific Research Council (CSIC), the Spanish Ministry of Economy and Sustainability (Project AGL2011-23802), and the Generalitat Valenciana (Project Prometeo 2012/064). R. Altamirano-Fortoul would like to thank her PhD Grant to CSIC.Altamirano Fortoul, RDC.; Hernández Muñoz, PA.; Hernando Hernando, MI.; Molina Rosell, MC. (2015). Mechanical, microstructure and permeability properties of a model bread crust: Effect of different food additives. Journal of Food Engineering. 163:25-31. https://doi.org/10.1016/j.jfoodeng.2015.04.019S253116

Stability of Lactobacillus rhamnosus GG in prebiotic edible films

The concept of prebiotic edible films as effective vehicles for encapsulating probiotic living cells is presented. Four soluble fibres (inulin, polydextrose, glucose-oligosaccharides and wheat dextrin) were selected as prebiotic co-components of gelatine based matrices plasticised with glycerol and used for the immobilisation of Lactobacillus rhamnosus GG. The addition of prebiotics was associated with a more compact and uniform film structure, with no detectable interspaces or micropores; probiotic inclusion did not significantly change the structure of the films. Glucose-oligosaccharides and polydextrose significantly enhanced L. rhamnosus GG viability during air drying (by 300% and 75%, respectively), whilst a 33% and 80% reduction in viable counts was observed for inulin and wheat dextrin. Contrarily, inulin was the most effective at controlling the sub-lethal effects on L. rhamnosus GG during storage. However, in all cases the supplementation of edible films with prebiotics ameliorated the storage stability of L. rhamnosus GG

Influence of amyloglucosidase in bread crust properties

Enzymes are used in baking as a useful tool for improving the processing behavior or properties of baked products. A number of enzymes have been proposed for improving specific volume, imparting softness, or extend the shelf life of breads, but scarce studies have been focused on bread crust. The aim of this study was to determine the use of amyloglucosidase for modulating the properties of the bread crust and increase its crispness. Increasing levels of enzyme were applied onto the surface of two different partially bake breads (thin and thick crust bread). Amyloglucosidase treatment affected significantly (P<0.05) the color of the crust and decreased the moisture content and water activity of the crusts. Mechanical properties were modified by amyloglucosidase, namely increasing levels of enzyme promoted a decrease in the force (Fm) required for crust rupture and an increase in the number of fracture events (Nwr) related to crispy products. Crust microstructure analysis confirmed that enzymatic treatment caused changes in the bread crust structure, leading to a disruption of the structure, by removing the starchy layer that covered the granules and increasing the number of voids, which agree with the texture fragility.Authors acknowledge the financial support of Spanish Ministry of Economy and Sustainability (Project AGL2011-23802), the European Regional Development Fund (FEDER), Generalitat Valenciana (Project Prometeo 2012/064) and the Consejo Superior de Investigaciones Cientificas (CSIC). R. Altamirano-Fortoul would like to thank her grant to CSIC. The authors also thank Forns Valencians S. A. (Spain) for supplying commercial frozen partially baked breads.Altamirano Fortoul, RDC.; Hernando Hernando, MI.; Molina Rosell, MC. (2014). Influence of amyloglucosidase in bread crust properties. 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Stability of Lactobacillus rhamnosus GG incorporated in edible films: impact of anionic biopolymers and whey protein concentrate

The incorporation of probiotics and bioactive compounds, via plasticised thin-layered hydrocolloids, within food products has recently shown potential to functionalise and improve the health credentials of processed food. In this study, choice of polymer and the inclusion of whey protein isolate was evaluated for their ability to stabalise live probiotic organisms. Edible films based on low (LSA) and high (HSA) viscosity sodium alginate, low esterified amidated pectin (PEC), kappa-carrageenan/locust bean gum (κ-CAR/LBG) and gelatine (GEL) in the presence or absence of whey protein concentrate (WPC) were shown to be feasible carriers for the delivery of L. rhamnosus GG. Losses of L. rhamnosus GG throughout the drying process ranged from 0.87 to 3.06 log CFU/g for the systems without WPC, losses were significantly reduced to 0 to 1.17 log CFU/g in the presence of WPC. Storage stability (over 25d) of L. rhamnosus GG at both tested temperatures (4 and 25°C), in descending order, was κ-CAR/LBG>HSA>GEL>LSA=PEC. In addition, supplementation of film forming agents with WPC led to a 1.8- to 6.5-fold increase in shelf-life at 4°C (calculated on the WHO/FAO minimum requirements of 6 logCFU/g), and 1.6 to 4.3-fold increase at 25°C. Furthermore probiotic films based on HSA/WPC and κ-CAR/LBG/WPC blends had both acceptable mechanical and barrier properties