Physicochemical and techno-functional characterization of fibers and powders from leaves of stubble of two cultivars (MD2 and Smooth Cayenne) of pineapple (Ananas comusus L.)

Abstract

The aim of this work was to characterize the physicochemical and techno-functional properties of the fibers and powder obtained from the leaves of the two pineapple cultivars, MD2 (MD) and Smooth Cayenne (SC), to investigate their potential as a food ingredient in the development of new food products. Proximal chemical analysis shows that all evaluated materials have a low moisture content between 8.61 and 9.70% and a fat content between 0.06 and 1.04%, while the protein content varies between 5.32 and 8.36% and the ash content is higher in the powders than in the fibers (7.37 to 7.16 and 5.62 to 5.41, respectively). In addition, the samples have a high content of carbohydrates such as cellulose, hemicellulose, lignin, pectin, gum, wax and dietary fiber, which were identified by X-ray diffraction. The samples are acidic with a pH around 4.8. The results show that the fibrous (F) and the powder (P) materials have a swelling water capacity (SWC) between 16.14 and 26.90 mL g⁻¹, an oil retention capacity (ORC) between 2.95 and 7.26 g g⁻¹, a water absorption index between 8.20 and 13.25 g g⁻¹ and a high and low water solubility index (WSI) between 0.040 and 0.060 g g⁻¹. On the other hand, the color is similar for the fibers (FMD–FSC) and slightly different for the powders (PMD–PSC). Scanning electron microscopy shows that the fibers have a micrometric thickness of 5 to 10 μm and the powders have a particle size of 5 to 50 μm. X-ray fluorescence shows that the ash powder contains important minerals for the human body, such as K, Ca, Cl, P, S, Mg, Si, and Mn. The carbohydrates have an influence on the techno-functional and pasting properties of the powder as well as on the hydrophilic properties, which are reflected in the high peak viscosity. This fact can confirm and improve the prospects for its use as an ingredient in the food industry, following a circular economy approach, since the industry considers it as waste without value.