Effect of enzymatic maceration and homogenization by shear on the stability of pumpkin suspension (Cucúrbita maxima) incorporating its vegetable co-products (peel and seed)

Abstract

Background: Pumpkin fruits have worldwide agro-industrial importance and are rich in carotenoids, vitamins, and minerals. However, during processing, their peels and seeds, which have a high nutrient content, are generally discarded as solid waste. This work aimed to evaluate the influence of the processes of enzymatic maceration and homogenization by shear on the stability of a suspension of the pumpkin (pulp+seed+peel). Methods: A centralized composite design was used considering the enzyme dose (X1) with filter paper units (FPU) (21, 31, 42/g dry basis (db)) of substrate, hydrolysis time (X2) (2, 3.5, 5 h), and homogenization time (X3) (5.0, 7.5, 10.0 min), and the following  variables were measured: zeta potential (ζ), particle size, apparent viscosity (µ), spectral absorption R index, total carotenoid, and antioxidant capacity by DPPH⸳ (2,2-diphenyl -1-picrylhidrazyl radical) and ABTS•+ (2,2´-azinobis- (3-ethylbenzothiazoline-6-sulphonate). A theoretical optimization and experimental validation were performed using the desirability approach with multiple responses. Results: The optimization had a desirability function (79.9%), X1: 42 FPU/g db, X2: 4.68 h, and X3: 8.54 min. The ζ and the antioxidant capacity by ABTS•+ were not affected by the independent variables, nor by their interactions. Particle size D [4;3], R index, and antioxidant capacity by DPPH⸳ were mainly affected by X3, while D [3;2], and total carotenoid content were significantly affected by the interaction of X1 and X2. The optimal suspension achieved µ: 369.5 ±59.8 mPa.s, ζ: -28.2±0.6 mV, D[3;2]: 51.18±2.2 μm, D[4;3]: 333±17.4 μm, R Index: 0.43±0.02, total carotenoid: 127.9±9.3 mg/100g db, and antioxidant capacity (DPPH⸳:1083.9±23.9 and ABTS•+: 1485.1±27.1 µmol Trolox Eq/ 100g db). Conclusions: The process of enzymatic maceration and homogenization by shear made it possible to obtain an integral suspension of pumpkin with physicochemical stability and functional attributes, promoting a product with optimal conditions for its potential use in technological applications such as spray drying.