To achieve a "fluid gel" using high acyl (HA) gellan gum in vegetable drinks, like almond-based beverages, several factors related to the process and formulation should be optimized. 

Here's a detailed method you can try:

1. Dispersion:

  • Cold Dispersion: Gellan gum HA should be dispersed in cold water (or below 40°C) to ensure proper hydration. Use a high-shear mixer to disperse the gum evenly to prevent clumping. Gellan gum must be well dispersed before any heat is applied to avoid premature gelation.
  • Carrier for Dispersion: You can pre-mix gellan gum with other dry ingredients (e.g., sugar) to aid in the even distribution. Adding the gum directly to a liquid without proper dispersion might cause issues like localized gelation.

2. Heating Process:

  • Hydration Temperature: Gellan gum HA requires heating to hydrate fully. It dissolves around 85-90°C. During the UHT treatment (typically above 135°C for a short time), it should completely dissolve without forming a solid gel.
  • Avoid Overheating: Gellan gum HA needs to dissolve during the heat treatment but should not be heated excessively after it’s fully dissolved, as this may lead to over-gelation. Ensure that the gum is fully hydrated before the product is subjected to rapid cooling.

3. Cooling Step for Fluid Gel:

  • Controlled Cooling: After the UHT treatment, allow the product to cool gradually under constant stirring. Cooling too quickly or without agitation may lead to unwanted gelation. Aim to cool down to 30-50°C slowly while applying mechanical stress.
  • Stirring During Cooling: During the cooling process, mechanical stress (continuous stirring or gentle homogenization) breaks the forming gel network, transforming it into a fluid gel rather than a solid one. This is key to preventing the formation of a firm gel and achieving the smooth, fluid-like texture.

4. Mechanical Stress:

  • Shear Mixing: Mechanical stress is crucial to form a fluid gel. Use high shear mixing during the cooling process to break down the gellan gum’s gel network into fine particles, creating a fluid gel structure. A homogenizer can help achieve the desired smooth consistency.
  • Constant Agitation: Keep the mixture agitated while cooling to prevent the gum from settling into a gel structure. Agitation ensures a uniform fluid gel rather than a solid gel.

5. Dosage:

  • Optimal Dosage: The dosage of 0.02-0.03% gellan gum HA is generally appropriate for creating fluid gels in beverages. If you notice some gelling, you might consider reducing the concentration slightly or increasing the cooling time under mechanical stress.
  • Potential Increase in Dosage: If the fluid gel is too weak, you could increase the gellan gum HA to 0.03-0.04%, but be cautious, as higher concentrations could make it more difficult to achieve a fluid gel.

6. Additional Considerations:

  • Calcium Interaction: Almond drinks fortified with calcium can trigger gelation, as calcium ions help form stronger gels with gellan gum. To mitigate this, consider using a sequestrant like sodium citrate, which binds calcium ions and prevents them from interacting with the gellan gum.
  • Fat and Protein Interaction: The low fat and protein content in almond drinks (1.1g and 0.4g, respectively) means there’s minimal interference with gellan gum’s gelling action. If increasing the fat content, proper emulsification is necessary to maintain consistency.

Key Process Overview:

  1. Disperse the gellan gum in cold water (below 40°C) using a high-shear mixer.
  2. Heat the solution to 85-90°C to fully hydrate the gellan gum during UHT treatment.
  3. Apply mechanical stress (e.g., stirring or homogenization) during cooling to around 30-50°C.
  4. Slow cooling and constant agitation are key to breaking the gellan gum network and achieving a fluid gel.

By refining your heating and cooling processes and applying mechanical stress during cooling, you should achieve the desired "fluid gel" consistency in your almond-based drinks without the formation of a solid gel. Let me know if you need further adjustments or more details!