The valorisation of broccoli by-products to design a new functional pasta

Abstract

The demand for new food products with additional health benefits is growing mostly due to an ageing population and increasing health-conscious consumers. Fruit and vegetable by-products have been described as good sources of bioactive compounds with important biological activities such as antioxidant properties. Broccoli leaves are usually perceived as a waste product of broccoli processing. Studies have reported that similarly to the edible parts, broccoli leaves contain large amounts of phytochemicals thus they can be used to design novel food products. In this context, the main objective of this work was to develop a new functional pasta product enriched with broccoli leaf powder (BLP) up to concentrations of 5%. The effects on the technological parameters, sensory properties, chemical composition, volatile profile, and antioxidant capacity of the fortified pasta samples were evaluated in comparison with a control sample. BLP was a good source of nutritional components, including proteins and minerals, and bioactive compounds such as glucosinolates (GLS) and phenolics. The addition of BLP to pasta resulted in an improvement of several nutritional properties, which was demonstrated by a significant increase in the ash content. The incorporation of BLP influenced the content of GLS in pasta. GLS content was higher than expected, which could be attributed to the release of partially bound GLS during thermal processing. Neoglucobrassicin and glucobrassicin were the predominant GLS in BLP and in pasta. The addition of BLP to pasta increased their total phenolic content (TPC) and antioxidant activity (determined by ABTS and FRAP assays). Cooking loss increased with the addition of 2.5% of BLP, however, all pasta samples were in the acceptable range of 8g/100g. BLP incorporation decreased optimal cooking time and water absorption but increased the swelling index. Regarding colour and texture parameters, lightness (L*), redness (a*), firmness and total shearing force decreased as the amount of BLP in pasta increased, while yellowness (b*) increased. The volatile profile of pasta changed due to the addition of BLP. Dimethyl sulfide, detected in supplemented pasta after BLP incorporation, contributed to pasta flavour with a sulphurous cabbage-like odour. However, the sensory evaluation results indicated that the addition of BLP did not affect the overall acceptance of pasta, since all samples had great sensorial score (9 on a 10-point scale). Thus, for concentrations up to 5% of BLP, pasta remained acceptable for its texture, appearance, odour, and taste. The obtained results indicated that BLP can be successfully used as an ingredient of pasta products. In conclusion, the addition of BLP to pasta allowed an improvement in the nutraceutical potential without compromising its technological and sensory quality. Therefore, broccoli leaves are an interesting alternative for the food industry to provide new value-added pasta products to consumers.

Date of Award	29 Mar 2022
Original language	English
Awarding Institution	Universidade Católica Portuguesa
Supervisor	Natalia Drabinska (Supervisor)