Use of Almond Skins to Improve Nutritional and Functional Properties of Biscuits: An Example of Upcycling

Upcycling food industry by-products has become a topic of interest within the frameworkof the circular economy, to minimize environmental impact and the waste of resources. This researchaimed at verifying the eectiveness of using almond skins, a by-product of the confectionery industry,in the preparation of functional biscuits with improved nutritional properties. Almond skins wereadded at 10 g/100 g (AS10) and 20 g/100 g (AS20) to a wheat flour basis. The protein content was notinfluenced, whereas lipids and dietary fiber significantly increased (p < 0.05), the latter meeting therequirements for applying "source of fiber" and "high in fiber" claims to AS10 and AS20 biscuits,respectively. The addition of almond skins altered biscuit color, lowering L* and b* and increasing a*,but improved friability. The biscuits showed sensory dierences in color, odor and textural descriptors.The total sum of single phenolic compounds, determined by HPLC, was higher (p < 0.05) in AS10(97.84 g/g) and AS20 (132.18 g/g) than in control (73.97 g/g). The antioxidant activity showedthe same trend as the phenolic. The p-hydroxy benzoic and protocatechuic acids showed the largestincrease. The suggested strategy is a practical example of upcycling when preparing a health-orientedfood product.