Safety and digestibility evaluation of L-β-galactoglucan: Implication for its use as a novel food ingredient

L-β-galactoglucan, a novel heteropolysaccharide produced through fermentation from Agrobacterium sp. FN01, was functionally characterized as a dietary fiber and evaluated for its potential as a food ingredient. We conducted Good Laboratory Practice (GLP)-compliant in vitro and in vivo studies in accordance with OECD guidelines. In vitro genotoxicity tests, including the bacterial reverse mutation test, mammalian chromosomal aberration test, and micronucleus test, showed no mutagenic or clastogenic activity under any test condition. A 90-day sub-chronic oral toxicity study in Sprague Dawley (SD) rats demonstrated no adverse effects in clinical pathology, organ weights or histopathology at dietary concentrations up to 48 g/kg diet, establishing a No Observed Adverse Effect level (NOAEL) of 48 g/kg diet (equivalent to 3.84 g/kg·bw/day). Physicochemical characterization indicated that l-β-galactoglucan is a high molecular weight polysaccharide. Its resistance to mammalian digestive enzymes, confirmed via a multi-step enzymatic digestion assay, supports its classification as a dietary fiber. Based on the substantial safety evidence, an acceptable daily intake (ADI) of 38.4 mg/kg·bw/day was established for the safe use of l-β-galactoglucan in human diets at intended levels.