Phase separation and gelation of gelatin-glucose syrup mixtures and gummy confections: Effects of moisture content, sugars, citric acid, and citrates

Abstract

Phase separation is a prevalent phenomenon in gummy confections, often arising from potential molecular incompatibility between gelatin and long-chain polysaccharides in glucose syrups (GS). This study focuses on analyzing the phase separation and gelling behaviors of gelatin-GS mixtures, elucidating the roles played by water content and small molecular weight (MW) additional ingredients. Mixtures with 6% gelatin, 40% GS, and varying portions of water, sucrose/allulose, citric acid (CA), and citrates (soluble/insoluble) were prepared. Phase separation behaviors were observed using inverted fluorescent microscopy, with the gel properties characterized using rheology, texture profile analysis (TPA), and water-holding capacity (WHC) analysis. The results highlight the significant impacts of these small MW components on biopolymer compatibility (cosolubility). In gelatin-GS-water mixtures, reducing the water ratio without the addition of sugars promoted phase separation towards the polysaccharide-rich morphologies, while enhancing the sol-gel transition and gel strength due to increased gelatin/water ratio. The incorporation of sucrose or allulose into gelatin-GS-water mixtures, without altering the gelatin/GS/water ratio, generally improved the protein-polysaccharide co-solubility during mixing but had an adverse overall effect on gel formation. Acidification with CA increased the surface charges of the proteins, enhancing the biopolymer miscibility and gelling performance. Soluble citrates, e.g., sodium citrate (SC) and potassium citrate (PC), promoted protein-polysaccharide miscibility and gelation at low concentrations (1–5%), but led to severe phase separation and weakened gelation at higher dosage levels (7.5–10%). In contrast, insoluble citrate, i.e., calcium citrate (CC), marginally enhanced the protein-polysaccharide miscibility while facilitating gummy gelation as an active filler.