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Please cite this article as: Mancebo, C.M., Rodriguez, P., Gómez, M., Assessing rice flour-starch-protein mixtures to produce gluten free sugar-snap cookies, LWT -Food Science and Technology (2015), doi: 10.1016/j.lwt.2015 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. The mixture of rice flours, starches and proteins is common in gluten-free bakery 13 products such as bread or cake. The aim of this study was to determine the effects of 14 starch and/or protein addition in rice flour gluten-free cookie quality. For this purpose, 15 the hydration and oil absorption properties of flour-starch-protein mixtures, dough 16 rheology and quality cookie parameters (thickness, final diameter, spread factor, texture, 17 colour and acceptability) were analysed. Generally, protein incorporation increased 18 hydration properties of the mixture and dough consistency, producing cookies with 19 limited spreading in the baking time, lower hardness values and darker colour. In 20 particular, protein addition reduced the width up to 8.4% and the hardness up to 10.60 21 % (control versus 20% of protein inclusion). However, maize starch addition reduced 22 hydration properties and gave rise to cookies with higher thickness and width, but the 23 texture and colour were not affected by the starch. Cookies with higher protein content 24 showed higher acceptability than cookies with higher starch content and no protein 25 addition. Therefore, protein and starch can be used in order to adjust the desired cookie 26 characteristics depending on the cookie formulation and the needs of manufacturers. 27 28 29

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Dietary fibre intake can help to improve the health of the population. Cookies are one of the most consumed bakery products. The aim of this study was to investigate the influence of different fibres on cookie quality. Soluble fibres (nutriose, inulin and polydextrose) decreased dough consistency favoured cookie spread during baking and produced wider and thinner cookies. In contrast, insoluble fibres (elongated and rounded) showed an opposite trend increasing dough consistency and giving rise to cookies with higher moisture, lower spread factor and higher hardness. Long insoluble fibres gave rise to harder cookies and with lower spread factor. Cookies made with soluble fibres were darker than the control cookie and cookies containing insoluble fibres. Therefore solubility and shape of insoluble fibres play an important role in cookie quality. Fibre selection will be key to enriched cookies development.

Gluten-free bread production requires gluten-free flours or starches. Rice flour and maize starch are two of the most commonly used raw materials. Over recent years, gluten-free wheat starch is available on the market. The aim of this research was to optimize mixtures of rice flour, maize starch and wheat starch using an experimental mixture design. For this purpose, dough rheology and its fermentation behaviour were studied. Quality bread parameters such as specific volume, texture, cell structure, colour and acceptability were also analysed. Generally, starch incorporation reduced G* and increased the bread specific volume and cell density, but the breads obtained were paler than the rice flour breads. Comparing the starches, wheat starch breads had better overall acceptability and had a greater volume than maize-starch bread. The highest value for sensorial acceptability corresponded to the bread produced with a mixture of rice flour (59 g/100 g) and wheat starch (41 g/100 g).

This study showed that the type and quantity of fat added in rice based breads affect the bread quality in a different way. In general, it can be said that the incorporation of up to 20% oil improved rice based breads. Oil increased the specific volume, the a* and b* parameters of the crust and the cell density. It also decreases hardness, cohesiveness, springiness, resilience, and the L* parameter. Converse to breads made with oil, the addition of shortening can negatively affect the quality of the breads. Moreover, the correlation analysis has demonstrated that the study of dough rheology could be a good predictor of gluten-free bread quality.

Es maravilloso finalizar una etapa de mi vida y poder estar agradecida a un sinfín de personas. A mis directores de tesis, Manuel Gómez y Pedro A. Caballero. Gracias por vuestro tiempo y dedicación, especialmente a Manuel por su paciencia en mis inicios en la redacción de artículos y por su profesionalidad. Gracias por haberme permitido conocer este mundo de la investigación en productos sin gluten que apenas conocía y que hoy encuentro tan fascinante. A mis Lauras, grandes personas y amigas. Laura Román, mi compañera de doctorado, de faena en el laboratorio y seminario. Juntas hemos compartido congresos, gimnasio, cenas y risas. Gracias por estar ahí. No se te puede no querer. Y a mi Laura Pascual, que comenzó como técnico de laboratorio y a la que he empujado para seguirme en nuestra nueva aventura profesional, porque confío en ti y porque te quería a mi lado, y todo por cómo eres. Mi compañero de doctorado y amigo Mario Martínez por enseñarme a trabajar en el laboratorio, por escucharme y aconsejarme a su manera en la toma de decisiones, por esas largas charlas sobre investigación, nuestro presente y nuestro futuro, sobre la vida, … Por hacerme un hueco en su divertido entorno palentino y por hacerme reír una y mil veces. A las chicas que han colaborado con nuestro grupo de investigación durante mis años de doctorado. Cristina Noemi Segundo, más conocida cariñosamente como "Cristina la argentina" tan graciosa y divertida. A Nahla Dhen con la que aprendí una cultura diferente. Gracias por hacer la vida del laboratorio más amena y enriquecedora. Que cortita se me hizo vuestra estancia… y es que cuando se está trabajando bien con alguien, todo pasa más deprisa. Ojalá volvamos a encontrarnos. A Joana Pico, una química excelente con la que me hubiera gustado trabajar más codo con codo, pues es una investigadora increhíble de la que se puede aprender mucho. Me alegro de que hayamos compartido juntas cursos, congresos y confesiones. Echaré de menos tu naturalidad que te hace única. A todos los que han sido compañeros de laboratorio y amigos, especialmente a los que han contribuido en la parte experimental