Bergamot belongs to the Rutaceae family and is a typical fruit grown principally in the province of Reggio Calabria (South Italy). Nowadays, its industrial use is mostly related to the extraction of the essential oil contained in the flavedo but also to a lesser extent the extraction of the juice (from the pulp), which is rich in antioxidants. However, the pressed pulp (known as Pastazzo) is either used for animal feed or is discarded. The aim of this research was to study the effect of bergamot Pastazzo flour in shortbread biscuits. Pastazzo flour partially replaced the 00 wheat flour in different percentages (2.5%, 5%, 10% and 15%). Simultaneously, a sample without the addition of pastazzo flour (control) was analyzed, thus obtaining five biscuit samples. Cooking was done in a ventilated oven at 180 °C. The baking time was different for the control and the enriched samples depending on when the desired color was reached. The control took 12 min, while the enriched samples reached the desired color in 8 min. All samples were subjected to physicochemical and antioxidant characterization, as well as total polyphenols and flavonoids. The use of pastazzo flour resulted in a slight increase in water activity and humidity values. pH values decreased for all the enriched samples compared to the control, but this was more relevant for the samples enriched with 10 and 15% of flour from by-products. Hardness varied from 1823 g (Control) to 2022 and 2818 g (respectively, for 2.5% and 15% bergamot Pastazzo flour in the recipe). Total phenol content varied from 0.14 mg GAE g−1 (Control) to 0.60 and 3.64 mg GAE g−1 (respectively, for 2.5% and 15% bergamot Pastazzo flour in the recipe). The obtained results demonstrated that the use of pastazzo flour had a positive influence on the antioxidant content, with values which increased as more pastazzo flour was added.

In this study, dry orange peel was added to an orange marmalade as an alternative for pectin. The product stability and the antioxidant effect on shelf life of this enriched marmalade were evaluated. In particular, the hydroxymethylfurfural formation in correlation with major bioactive compounds, antioxidant assay, total phenols and anthocyans were estimated during storage at 20 and 35 °C for 150 days. The level of phenols ranged from 73.65 to 147.67 mg/100 g for control samples and from 110.09–157.32 mg/100 g for enriched samples. The initial HMF content was 0.09 mg/100 g for the control marmalade and 0.16 mg/100 g for enriched samples and during storage, the level increased. Obtained data show that incorporation of orange peel in marmalade production can be a valid use of this by‐product. After storage, the enriched samples at 20 °C maintained the analytical parameters better than the samples stored at 35 °C. Practical applications The citrus fruit residues, which are usually discarded as waste can be used as nutraceutical resources. The utilization of these bioactive rich citrus residues can serve for the production of novel products or for the improvement of those already in use. Orange peel contains significant amounts of phenolic compounds especially phenolic acids and flavonoids, thus we can consider it a potential material for the formulation of nutraceuticals and food preservatives and may be used as a possible functional ingredient in alimentary products such as marmalade.