TECHNOLOGICAL AND FUNCTIONAL POTENTIAL OF FORAGE CACTUS VARIETIES: A MORPHOCHEMICAL CHARACTERIZATION BY SEM AND FTIR

Forage cactus, considered an Unconventional Food Plant (UFP), exhibits high water resilience and a composition rich in fibers, mucilages, and bioactive compounds, making it strategic for arid and semi-arid regions. Its use in higher value-added applications, such as sustainable packaging and functional ingredients, represents a promising alternative to its traditional role as animal fodder. This study aimed to morphologically and chemically characterize four varieties of forage cactus (Sertânia, Elefante, Miúda, and Gigante), with emphasis on identifying cellular structures and functional groups with technological potential. Analyses were performed using scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). FTIR spectra were obtained with an Agilent Cary 630 spectrophotometer equipped with a UATR accessory, operating from 4000 to 500 cm⁻¹, at a resolution of 4 cm⁻¹ and 16 scans. Samples for SEM were fixed with conductive carbon tape, gold-coated in a Sputter Q150R ES, and examined in a HITACHI TM-3000 microscope (15 kV) at magnifications from 100× to 5000×. The SEM images revealed cellular matrices composed of soluble components (mucilages, pectins) and insoluble components (cellulose, hemicellulose, and lignin), as well as elongated fibers, parenchymal cells, laminar structures, and porous networks. The Sertânia variety showed more compact and parallel fibers; Elefante displayed a more porous structure; while Miúda and Gigante exhibited similar morphology, with intertwined fibers and collapsed lamellae. FTIR spectra revealed bands at ~3259–3276 cm⁻¹ (O–H), indicating mucilages and pectins; ~2915–2924 cm⁻¹ (CH₂/CH₃), related to hexoses; ~1027–1034 cm⁻¹, corresponding to glycosidic bonds of polysaccharides; ~1576 and ~1388 cm⁻¹, associated with amides and uronic acids; and a discrete signal at ~2100 cm⁻¹, suggesting phenolic compounds. Overall, the results demonstrate that these forage cactus varieties possess cell walls rich in hydrophilic and fibrous fractions, notably functional polysaccharides, cellulosic fibers, and phenolic compounds. The combined SEM and FTIR analyses elucidated subtle structural differences among the varieties, reinforcing the potential of forage cactus for innovative and sustainable applications aligned with the United Nations Sustainable Development Goals (SDGs), particularly SDG 2 (Zero Hunger and Sustainable Agriculture), SDG 9 (Industry, Innovation, and Infrastructure), and SDG 12 (Responsible Consumption and Production).