Effects of Blanching and Gamma Irradiation on Jerusalem Artichoke (Helianthus tuberosus L.) Powder Properties

Abstract

Jerusalem artichoke powder (JAP) is a natural source of inulin but presents limited hydration and adsorption properties, highlighting the need for improved processing methods to enhance functional food applications. This study evaluated the effects of thermal pretreatment (blanching at 100°C for 2 min; B) combined with gamma irradiation (0–10 kGy; IR) on the functional and structural properties of JAP. Samples were assessed for hydration capacity, glucose adsorption, antioxidant activity, carbohydrate content, and molecular structure using FTIR and ¹H NMR spectroscopy. The treatment combining blanching and irradiation at 2.5 kGy (B-IR2.5) produced the most significant improvements, with water holding capacity increasing to 11.8 g/g, swelling capacity to 17.8 g/g, and glucose adsorption reaching 148 mmol/g. Antioxidant activity also improved, with total phenolic content rising to 60 mg GAE/g in nonblanched samples irradiated at 7.5 kGy (NB-IR7.5). Protein and total dietary fiber contents increased to 11.94 and 28.6 g/100 g, respectively, while reducing sugar and inulin contents were reduced due to thermal degradation. FTIR analysis revealed stronger signals in hydroxyl and glycosidic bond regions, while ¹H NMR spectra of B-IR and NB-IR at 2.5 kGy showed reduced signal complexity and patterns similar to those of commercial short-chain inulin. An optimized combination of blanching and low-dose gamma irradiation enhances key functional and structural attributes of JAP, making it suitable as an alternative dietary fiber source in functional food applications.