Upcycling agricultural by-products: Optimization of crude protein recovery from sugar beet leaves and its functional attributes

Title : Upcycling agricultural by-products: Optimization of crude protein recovery from sugar beet leaves and its functional attributes

Abstract:

The valorization of agricultural by-products as alternative plant-based protein sources has gained significant attention. This study aimed to obtain and characterize crude protein powder from sugar beet (Beta vulgaris L.) leaves through an optimized conventional alkaline extraction process. Briefly, green sugar beet leaves were dried in a laboratory oven at 38^°C, pulverized into powder, and preserved at -20^°C. To maximize extraction efficiency, three independent variables were optimized: pH (7–11), temperature (30–50^°C), and time (5–45 min).

The optimization evaluated two dependent responses: soluble protein ratio and crude protein powder amount. The developed statistical models demonstrated high predictive reliability, yielding R² values of 87.35% for the soluble protein ratio and 86.64% for the crude protein powder amount. According to the Pareto chart of standardized effects, the quadratic effect of temperature and the linear effect of time were the most significant parameters influencing the soluble protein ratio. Conversely, the crude protein powder yield was predominantly affected by the quadratic effect of pH and the linear effect of temperature.

The optimum extraction conditions were determined as a temperature of 37.5°C, a processing time of 45 min, and a pH of 9.9. The crude protein powder produced under these optimized conditions was subsequently analyzed for its compositional and techno-functional properties. Elemental analysis revealed a total protein content ratio of 47.43 ± 0.00%. Furthermore, the optimized protein extracts exhibited a water holding capacity of 1.82 ± 0.01 g water/g protein and an oil binding capacity of 2.91 ± 0.01 g oil/g protein. The foaming capacity and foam stability of the extracts were recorded as 0.80 ± 12.25% and 95 ± 2.3%, respectively. These findings demonstrate that optimized alkaline extraction successfully yields functional crude protein from sugar beet leaves, underscoring its potential viability as a sustainable ingredient for food applications.

Keywords: Response Surface Methodology, Food Waste Recovery, Leaf Protein Concentrate, Circular Economy.

Biography:

Dr Erdgan Kucukoner is a distinguished professor in the food engineering department at Suleyman Demirel University. He completed his PhD in Food Science and Technology at Mississippi State University. He has led multiple research projects and advised students in academic and research activities. He has served as Dean of the Faculty of Engineering at Suleyman Demirel University. He also served on the food advisory board and the executive board of the Agriculture, Forestry and Veterinary Research Group at The Scientific and Technological Research Council of Turkey. Kucukoner has over 100 national and international scientific publications and numerous conference presentations in the field of Food Science and Technology.