Challenge of no-added-sugar jam: Conventional HM pectin jam relies on high sugar (≥60° Brix) for gelation via dehydration and depressed water activity. In reduced-calorie formulations (25–35° Brix), HM pectin cannot form a stable network — LM amidated pectin or gellan must substitute.
Option comparison:
• Amidated LM pectin alone (1.0–1.2%): Good fruit flavor release, moderate gel strength, requires Ca²⁺ control. Spreadability index (penetration at 5 g probe) ~85 mm — excellent.
• Low-acyl gellan (0.15–0.25%) alone: Strong, brittle gel; poor spreadability (~45 mm). Not recommended alone for jam.
• Blend: Amidated LM pectin 0.8% + Gellan 0.10%: Gellan micro-structures the amorphous pectin network, increasing rigidity while pectin maintains spreadability. Spreadability ~70 mm, no syneresis at 12 months.
✦ Low-calorie jam formula: Amidated LM pectin 0.8% + Low-acyl gellan 0.10% + Inulin HP 5% + Calcium lactate 0.3% + Steviol glycoside 0.05% + Fruit puree 50%, pH 3.2–3.5, Brix 28–32°
Inulin effect on microstructure: Inulin (DP >23) forms co-crystalline microfibril networks at ≥5% that interpenetrate with the polysaccharide gel, increasing G' by 20–30% and providing a creamier mouthfeel. Avoid inulin >8% — retrograde crystallization creates sandy texture after 4 weeks.
