Development of new food products of high nutritional and functional value using flowers, fruits and plant stems

Resumo

Sustainable food options are becoming more prevalent to respond to needs from consumers, which seek to combinations of new ingredients with potential health benefits. In this work, edible flowers and infusions of Dahlia mignon, a mixture of roses (Rosa damascena ‘Alexandria’ and R. gallica ‘Francesa’ draft in R. canina), Calendula officinalis L., Centaurea cyanus L., fruits of Vaccinium myrtillus L., Malus domestica Borkh apples, and Lycium barbarum L. fruits and stems were characterized regarding their proximate composition, soluble sugars, organic acids, individual phenolic profile and bioactive potential (antioxidant and antibacterial activities for all samples, and antiproliferative capacity for flowers and their infusions). Furthermore, the flowers, fruits and stems were also characterized in terms of their fatty acid and tocopherol profiles. Carbohydrates were the most abundant macronutrients in all the studied samples, with fructose, glucose and sucrose being identified in all the flowers and their infusions. Rose flowers and C. officinalis infusions showed the highest content of organic acids, with the latter also being the one with the highest quantity of tocopherols. In all samples, polyunsaturated fatty acids predominated over the saturate. The different studied flowers revealed distinct phenolic composition, but all showed high biological potential, in which hidromethanolic extracts of rose flowers revealed the greatest bioactive properties. Besides the high nutritional value and the diverse chemical composition, the extracts prepared from ‘Bravo de Esmolfe’ apples, showed a characteristic phenolic profile with presented epicatechin and B-type procyanidins, hydroxycinnamoyl-quinic acids and phloretin derivatives, while also showing antioxidant and antibacterial effects. Stems of L. barbarum presented higher values of energy, monounsaturated fatty acids, tocopherols and flavonols, as well as great antioxidant and antibacterial activities than fruits, while these latter revealed higher contents of sugars, PUFA and hydroxycinnamic acid derivatives, as also greater activity against Gram-positive bacteria. Since the food industry is always seeking innovative approaches to maintain consumers’ interest and fulfil their awareness towards the healthiness of diets, a great interest has been given to natural food additives, namely colourants. In this sense,aqueous extracts from rose mixture, C. cyanus and D. mignon and a hydroethanolic extract obtained from V. myrtillus were tested as potential substitutes to E163 (anthocyanins). Besides comparing the colouring capacity, the potential occurrence of changes in the chemical composition of yogurts added with the colouring extracts (nutritional parameters, free sugars and fatty acids) was also assessed throughout storage (up to 7 days) and compared with a plain (free of any colourant) yogurt formulation. In general, yogurts prepared with flower and bilberry fruits extracts presented similar nutritional value and free sugars profile to those prepared with E163 and to the plain yogurt. Nevertheless, rose extract turned out to be the most suitable alternative to E163 as these two groups of yogurts presented close scores in colour parameters, besides having similar nutritional, free sugars and fatty acids composition. For their part, bilberry extracts showed lower colouring capacity when compared to E163, but it provided higher stability throughout storage. Another advantage of this natural extract was the potential bioactive properties that it can confer to foods, due to its high content in bioactive compounds. The sustainable exploitation of fruit and cereal processing by-products is being conducted for the development of new food products, including snacks. The consumption of these type of products has gained a significant importance worldwide and in consumer’s health, since nowadays they represent an important source in the daily intake of nutrients for some groups of individuals. The development of V. myrtillus-based snacks could, therefore, be an answer for the food industry, due to the nutritional properties of these fruits, but also to their content in high added value compounds and bioactive potential. Having this in mind, three bilbery fruits-based snacks supplemented with edible flowers and fruits were developed and characterized for their nutritional value and contents in fatty acids, sugars, organic acids, tocopherols, and phenolic compounds, as well as their antioxidant, antibacterial and hepatotoxic properties. The incorporation of edible flowers and fruits to the bilbery snacks improved their nutritional, chemical and bioactive inputs, leading to higher content in phenolic acids and anthocyanins, and also higher antioxidant and antibacterial activities. The results obtained throughout this thesis work are expected to be useful to fulfil the pressing need of the food industry to develop new functional food products.