Reuse of Agroindustry By-Products to Produce New Fibre Enriched Bread Formulations: Impact in Physico-Chemical, Sensorial and Nutritional Characteristics
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Reuse of agroindustry by-products to produce new fibre enriched bread formulations: impact in physico-chemical, sensorial and nutritional characteristics Thesis submitted to Universidade do Porto, in partial fulfilment of requirements for the PhD degree in Sustainable Chemistry Zita Emanuela de Sá Veloso Martins Under the supervision of: Associate Professor Isabel Maria Pinto Leite Viegas Oliveira Ferreira And the co-supervision of: Cathedratic Professor Olívia Maria de Castro Pinho Porto May, 2017 ©AUTHORISED THE COMPREHENSIVE REPRODUCTION OF THIS THESIS ONLY FOR RESEARCHE PURPOSES THROUGH A WRITTEN DECLARATION OF THE INTERESTED PARTY THAT IS COMMITTED TO SUCH PLEDGES. ii This work has been supported by Fundação para a Ciência e Tecnologia (FCT) through PhD grant (FRH/BD/87461/2012) financed by Programa Operacional Potencial Humano - Quadro de Referência Estratégico Nacional - Tipologia 4.1 - Formação Avançada (POPH - QREN) subsidised by Fundo Social Europeu (FSE) and national funds from Ministério da Ciência, Tecnologia e Ensino Superior (MCTES). iii The experimental work presented in this thesis was undertaken under the Ph.D. Programme in Sustainable Chemistry (REQUIMTE), hosted by Universidade do Porto and Universidade Nova de Lisboa. The experimental work was mainly performed in the Laboratory of Bromatology and Hydrology, Department of Chemical Sciences, Faculty of Pharmacy, University of Porto (Portugal). iv Aos meus pais, avós, irmão e Ricardo v vi AKNOWLEDGEMENTS Chega, ao fim de quatro anos, a derradeira etapa da minha formação académica. Não posso deixar de agradecer a todos os que a tornaram possível e que contribuíram direta ou indiretamente para que esta tese fosse concluída. Em primeiro lugar quero agradecer à Professora Isabel, por me ter recebido e aceitado ser minha orientadora. Agradeço toda a dedicação, trabalho, ajuda, orientação e amizade que sempre demonstrou ao longo destes anos. A sua ajuda e acompanhamento foram fundamentais em cada passo desta etapa. Agradeço do fundo do coração a oportunidade que me deu e por me permitir crescer e evoluir profissionalmente. Quero também agradecer à Professora Olívia, por me ter aberto as portas que tornaram o meu doutoramento possível. Agradeço toda a dedicação, trabalho, ajuda, co-orientação e amizade, sem as quais não estaria aqui. À Dra. Eulália, por todo o apoio, amizade e carinho que sempre demostrou e, especialmente, por ser uma segunda mãe. Por isso, e por tudo o resto, ser-lhe-ei sempre grata. À Professora Susana, pelas conversas, boa disposição e por ter sempre uma palavra amiga. To Professor Becker, for the availability to receive and welcoming me in the Research Group Cereal Technology and Process Engineering of Technical University of Munich, and also for the help, knowledge, and friendship. To Mario, for welcoming me, for the availability, help, guidance, knowledge, and friendship throughout and after my stay at Freising. À Catarina, pela pessoa e amiga que é, e por ser sempre uma presença positiva na minha vida. Mesmo estando fisicamente distante, estás sempre no meu coração! Obrigada pela amizade, pelas conversas e por tudo, tudo, e tudo. Em especial, à Rebeca, Carla, Tânia, Carina e Madalena. Tenho muita sorte em vos ter como amigas. Rebeca, obrigada pelas confidências, conversas e boa disposição. Obrigada por tudo, por toda a ajuda, pela troca de conhecimento, espírito crítico e por estares sempre disponível. Carla, obrigada pelas conversas, por seres a minha companheira na saga da estatística e por me ajudares a manter a calma durante a fase de escrita. Carina, obrigada pela sinceridade, boa disposição e companhia na fase mais atribulada do trabalho de vii laboratório. Tânia, pela ajuda, troca de conhecimento e por seres uma excelente companheira de turismo científico (qual é o próximo?). Madalena, pela boa disposição e companheirismo. Ao Armindo, pela amizade e capacidade de fazer rir (és um bom contador de histórias e estórias). Obrigada pelo conhecimento, por toda a ajuda e disponibilidade. Ao Edgar e ao Miguel, pela ajuda, conhecimento e pelas conversas. To Steffi, Tini, Isabelle, Sabina, Dana, Maike, Silvia, Rita, Christoph, Florian, Michi, Raphael, Kerstin, and Stefan for everything! Thank you for the friendship and availability, for welcoming me and making me feel at home. Thank you for showing me the German culture and spirit. À Catarina (Zon zon), João (Bullying), João (Mci), Ricardo (Fúcsia), Sandy, Emanuel (Cozido), por serem os meus “piquenos” de Astronomia. Obrigada pela amizade e companheirismo. Ao Damião, Dores, Rita e Leila, por serem a minha segunda família. Obrigada por todo o apoio, amor, amizade e carinho. Aos meus pais e irmão, pelo amor incondicional, pelo apoio que sempre me deram e por estarem sempre presentes. Obrigada por tudo o que fizeram por mim e por serem um exemplo de determinação e luta. Sem vocês não seria a pessoa que sou hoje. Aos meus avós, pelo amor e carinho. Ao Ricardo, por ser o meu “Sun sun” e companheiro de vida. Não há palavras que cheguem para agradecer tudo o que fazes por mim. Obrigada pelo teu amor incondicional, amizade, carinho, companheirismo e compreensão. Obrigada pela paciência, principalmente nesta reta final (sei que não foi fácil). Finalmente, agradeço a todas as pessoas que, não estando aqui mencionadas, contribuíram de alguma forma para que este trabalho pudesse ser realizado. A todos, o meu MUITO OBRIGADA! “Not all those who wonder are lost” J.R.R. Tolkien, The Fellowship of the Ring viii ABSTRACT Bread is consumed in large quantities on a daily base and have an important role in human nutrition. The addition of functional ingredients to bakery products has risen in popularity due to the ability to reduce risk of chronic diseases beyond basic nutritional function. Food industrial by-products (BP) are rich sources of functional ingredients, such as fibre, minerals, and phytochemicals that are promising for improvement of nutritional quality of bread and may potentially enhance their health promoting properties. However, the incorporation BP functional ingredients also influence technological and sensorial properties. The work developed in this PhD thesis aimed to obtain new fibre rich ingredients from agroindustry BP and to produce new types of fortified bread with enhanced nutritional/health benefits, while assuring good sensory characteristics. In order to achieve these goals, preliminary studies were carried out using brewer’s spent yeast. Proteins/proteolytic enzymes from inner brewer’s yeast had a negative impact on bread physical properties, whereas β-glucan rich extract can improve bread technological and health promoting properties. As result, β-glucans (fibre) rich extract was selected as a potential functional ingredient. Moreover, three agroindustry BP of plant origin were also used to obtain fibre rich extracts: elderberry skin, pulp and seeds (for elderberry extract, EE); orange peel (for orange extract, OE); pomegranate peel and interior membranes (for pomegranate extract, PE). Different extraction procedures were optimized for each BP in order to obtain fibre rich extracts that were characterized concerning their fibre composition. Functional breads eligible for nutrition claims “source of fibre” and “high in fibre” were prepared through wheat flour replacement with YE (4%), EE (4 and 36%), OE (4 and 8%), and PE (4% and 16%). The impact of wheat flour replacement was evaluated on: i) dough mechanical properties, microstructure and fermentation; ii) bread volume, texture, and image analysis; ii) sensory properties and consumer preference. Finally, the impact of bread fortification on total and bioaccessible mineral composition, estimated mineral daily intake, and the relationship between bioaccessibility and dietary fibre was evaluated. Results showed that: i) optimum water absorption increased with higher concentrations of OE, PE, and YE; ii) development time for EE, PE, and YE was shortened while the opposite was observed for OE; iii) the onset of starch gelatinization and maximum tan δ significantly increased with 36% EE and 4% PE; iv) protein structure, observed with confocal laser scanning microscopy, was modified at varying extents by the addition of extracts, and were in accordance with results from fundamental rheology; v) maximum and final dough height significantly decreased, except for 4% EE. Wheat flour replacement also had impact on bread parameters, since: i) volume and specific volume decreased at the highest concentrations in every extract; ii) ix significant changes were observed in crumb texture and structure, at higher extract concentrations. Multivariate PLS regression highlighted relationships between dough and bread data, and suggested that TDF content seems to have a stronger influence than its composition (SDF and IDF fractions). Breads suitable for “high in fibre” claim (8% OE, 16% PE, and 36% EE) were not viable, due to the detrimental results on dough and bread properties. Nonetheless, it was possible to successfully obtain breads with the nutrition claim “source of fibre” (replacement at 4%). Data obtained from external preference mapping pointed the selection of fibre rich extracts concentrations with best acceptance i.e., 7.0% EE, 2.5% OE, 5.0% PE, and 2.5% YE. At these concentrations, all bread formulations were eligible for the nutrition claim “source of fibre”. Bread formulations with 7.0% EE and 5.0% PE registered more differences on colour and crumb structures than 2.5% OE and 2.5% YE, compared to control bread. Data collected from