Content of dietary fibre and phenolic compounds in broccoli side streamsBerndtsson, Emilia
Shortage of food is an alarming problem today, with up to 821 million people that are undernourished world-wide. At the same time, enough edible foodstuff to feed 1.9 billion people are wasted or lost in the food supply chain that for aesthetic reasons, handling and transportation inadequacies in the food supply chain and lack of market. In 2014, this wasted or lost food (including only commonly consumed plant parts) corresponded to 3.49 GT CO2 equivalents globally, which was more than half the total amount of emissions in the USA that year. This means that there is much biomass that could be valorised into nutritional food ingredients or used for extraction of health beneficial compounds, e.g. dietary fibre. Many consumers currently eat too little dietary fibre and phenolic compounds, which can lead to increased risk of developing some forms of cancer and cardiovascular diseases.
In this thesis, the content of dietary fibre and phenolic compounds in the broccoli leaves and stems was determined. The relationship between the dietary fibre and phenolic compounds in broccoli leaves was also analysed, since recent research indicates that interactions between these plant components may have an impact on the uptake in the human gastrointestinal tract. The results revealed that broccoli leaves contain similar levels of dietary fibre (26-32 % of dry weight (DW)) to cabbage, broccoli florets and kale leaves, which are regarded as beneficial to human health. The content of phenolic compounds (6.3-15.2 mg/g DW) in broccoli leaves was similar to that in kale leaves and much higher than that in broccoli florets. Some phenolic acids showed positive correlations with soluble dietary fibre in the broccoli leaves, but no correlation was found between the insoluble dietary fibre and phenolic compounds. A pilot study on field waste showed that leaves and stems of broccoli plants make up 43-87 % of total plant weight, indicating that substantial amounts of biomass are left in the field at harvest.
Overall, the analysis of this thesis showed that the broccoli leaves are interesting from a food ingredient perspective. Possible uses could be to add broccoli leaf powder to everyday food products, such as pasta or bread, or into gluten-free products to increase the nutritional and technical properties.
Keywordsbroccoli; dietary fibre; field waste:food loss; food waste; health benefits; phenolic compounds
ISBN: 978-91-576-9740-0, eISBN: 978-91-576-9741-7
Publisher: Swedish University of Agricultural Sciences, Department of plant breeding