Formation of Amylose–Lipid Complexes in Green Banana (Musa × paradisiaca) Flour Enriched with Hot-Pressed and Cold-Pressed Virgin Coconut Oil

Abstract

Featured Application: The findings of this study demonstrate the potential of banana flour incorporated with virgin coconut oil for the development of slightly lower digestible, starch-based food products. By promoting amylose–lipid complex formation, banana flour combined with virgin coconut oil can be transformed into a functional ingredient with reduced enzymatic digestibility, making it suitable for bakery products and gluten-free formulations that leverage reduced enzymatic accessibility of starch. This work examined the development of amylose–lipid complexes in green banana flour (Musa × paradisiaca) incorporated with virgin coconut oil (VCO), focusing on their spectral, thermal, and in vitro digestibility characteristics. Firstly, the native banana flour was analyzed for apparent amylose content using a spectrophotometric assay. To facilitate amylose–lipid complexation, both hot-pressed and cold-pressed VCO were incorporated into the banana flour under controlled thermal conditions, after which amylose–lipid interactions were characterized using Fourier-transform infrared and Raman spectroscopy for spectral features and differential scanning calorimetry for thermal behavior. The banana flour exhibited an AAC of 26.40 ± 0.002%. GCMS analysis of FAME derivatized VCO detected medium- to long-chain fatty acids, including octanoic (C8:0), decanoic (C10:0), dodecanoic (C12:0), tetradecanoic (C14:0), and hexadecanoic acids (C16:0) stearic acid (C18:0) and oleic acid (C18:1). FTIR coupled with multivariate analysis and Raman spectra confirmed lipid incorporation/retention in green banana flour through characteristic O–H, C–H, and C=O bands. While DSC revealed distinct endothermic transitions at 89.56 ± 2.17 °C (ΔHₘ = 0.8587 ± 0.1014 J g−1) for hot-pressed VCO and 89.18 ± 0.98 °C (ΔHₘ = 0.6267 ± 0.0777 J g−1) for cold-pressed VCO, consistent with the melting of V-type amylose–lipid complexes. Morphological analysis revealed that thermal treatment transformed native banana flour from irregular granular structures into an amorphous matrix via starch gelatinization, whereas subsequent incorporation of VCO promoted aggregation. In vitro enzymatic digestion showed a slight reduction in starch hydrolysis in VCO-treated samples. The incorporation of an exogenous lipid, such as VCO, into green banana flour promotes the formation of thermally stable amylose–lipid complexes that reduce enzymatic digestibility.