From General Thickener to 照護食-Compliant: Choosing the Right Texture Modifier
Walk into any Hong Kong pharmacy and you will find at least two or three thickening products on the shelf. Walk into a well-stocked care home kitchen and you may find several more. They look similar — white or off-white powder, sold in tins or sachets — but they behave very differently in food and in the body.
Choosing the wrong thickener does not just mean a meal that tastes wrong. It can mean a meal that appears to be at the prescribed IDDSI level in the kitchen but thins out to a dangerous consistency in the person’s mouth, or a drink that sets too thick, reducing fluid intake and contributing to dehydration. For any kitchen or care arrangement aiming to meet the HKCSS 護食標準 Care Food Endorsement Scheme standards or maintain IDDSI-compliant care, choosing the right texture modifier is a clinical decision, not a commodity decision.
The Two Main Categories
All food-grade thickeners used in dysphagia care in Hong Kong fall into one of two categories:
- Starch-based thickeners — typically modified corn starch or tapioca starch
- Xanthan gum-based thickeners — a microbial polysaccharide used as a hydrocolloid
There are also combination products that blend xanthan gum with other hydrocolloids (such as locust bean gum or methylcellulose) to modify the texture profile, but these are less common in the Hong Kong market.
Starch-Based Thickeners
How they work
Starch granules absorb water and swell, increasing the viscosity of the liquid. The thickening process continues after mixing — liquids thicken further as they stand.
Properties
| Property | Starch-based behaviour |
|---|---|
| Temperature stability | Thickens more in hot liquids; continues to thicken in cold |
| Time stability | Viscosity continues to increase after preparation — can overshoot target level if left to stand |
| Appearance | Opaque, mildly cloudy |
| Taste effect | Starchy aftertaste at higher doses; can affect flavour of tea and clear soups |
| Saliva interaction | Critical limitation: salivary amylase (an enzyme in saliva) breaks down starch — consistency thins significantly in the mouth |
| Syneresis | Liquid may separate from gel over time, especially when refrigerated |
| Cost | Generally lower cost per serving |
The amylase problem
The saliva interaction is the most clinically significant limitation of starch-based thickeners. When a person takes a mouthful of a starch-thickened drink, salivary amylase begins enzymatically degrading the starch immediately. By the time the bolus is in the pharynx — the critical moment for airway protection — the consistency may have thinned by one full IDDSI level compared to what was measured in the cup.
This means a starch-thickened drink that tests as Level 3 (Moderately Thick) in the kitchen may behave more like Level 2 or even Level 1 in the pharynx at the moment the swallowing reflex needs to respond. For a person with moderate dysphagia prescribed Level 3, this represents a real aspiration risk.
Research supporting this concern has been published in multiple peer-reviewed journals since the mid-2000s (Cichero et al., 2013 and subsequent IDDSI-related literature; readers should consult the IDDSI reference list at iddsi.net for specific citations).
When starch-based thickeners may still be used
Despite the amylase limitation, starch-based thickeners remain in use in some Hong Kong settings because of their lower cost and broader availability. They may be clinically acceptable when:
- The prescribed level has a sufficient safety margin (e.g., prescribing Level 3 knowing some thinning will occur — this requires explicit SLP decision and documentation)
- The product is used in food (not drinks), where the amylase effect is less significant
- Cost constraints make xanthan gum products inaccessible and no better alternative is available
Any use of starch-based thickeners should be documented in the individual’s dietary record with the prescribing SLP’s knowledge.
Xanthan Gum-Based Thickeners
How they work
Xanthan gum forms a stable gel network that does not depend on temperature or enzymatic activity for its viscosity. The gel is shear-thinning (becomes temporarily thinner under the mechanical action of swallowing) but recovers its viscosity rapidly, providing a controlled flow through the pharynx.
Properties
| Property | Xanthan gum behaviour |
|---|---|
| Temperature stability | Consistent viscosity in hot and cold liquids |
| Time stability | Viscosity stable after approximately 2–3 minutes; does not continue to thicken significantly |
| Appearance | Clear to slightly hazy; less cloudy than starch — preserves appearance of tea, water, and clear soups |
| Taste effect | Minimal taste impact at clinical doses; preferred for patients who are sensitive to flavour changes |
| Saliva interaction | Resistant to salivary amylase — maintains prescribed IDDSI level through the oral phase |
| Syneresis | Minimal — good stability in refrigerated drinks |
| Cost | Generally higher cost per tin, but requires smaller dose per serving |
HKCSS 護食標準 alignment
The HKCSS Care Food Endorsement Scheme’s technical documentation aligns with IDDSI methodology. IDDSI’s own reference literature and clinical guidance documents note that xanthan gum-based thickeners provide more reliable consistency stability — particularly the critical amylase resistance property.
For a kitchen seeking HKCSS endorsement, using xanthan gum products provides stronger consistency-testing reliability: the viscosity measured in the kitchen will more closely reflect the viscosity experienced in the person’s mouth during swallowing.
This does not mean starch-based products are categorically excluded from endorsement, but it means that documentation, testing protocols, and SLP prescription adjustments must be more carefully managed if starch-based products are used.
Practical Selection Criteria
When choosing a texture modifier for a care home kitchen or home care setting, evaluate these factors in order:
1. Match the prescribed IDDSI level reliably
The primary criterion is whether the product reliably achieves and maintains the prescribed IDDSI level. Test every new batch when it arrives — even the same product from the same brand can have slight batch variation. Use the syringe flow test for drinks; use the fork pressure or spoon tilt test for food thickeners.
2. Amylase stability for thin drink thickening
If the product is being used to thicken thin drinks (water, tea, broth) to Level 2 or Level 3, prefer xanthan gum-based products. The amylase degradation risk is too clinically significant to ignore at these levels.
For Level 4 (Extremely Thick) thickening of drinks, where the bolus spends longer in the oral phase, the amylase effect is somewhat less critical — but xanthan gum is still the preferred choice for HKCSS-endorsed practice.
3. Temperature compatibility
If the kitchen serves both hot (morning soup) and cold (iced lemon tea) thickened drinks, xanthan gum-based products perform more consistently across the temperature range. Starch products can behave unpredictably at high temperatures.
4. Preparation protocol support
The thickener should come with clear, dose-specific preparation instructions for each IDDSI level (e.g., “X grams per 200 ml to achieve Level 2; Y grams per 200 ml to achieve Level 3”). If the manufacturer provides only vague guidance (“add to desired consistency”), this is a quality signal — IDDSI-aligned products should specify doses by tested level.
5. Labelling and IDDSI alignment documentation
For HKCSS endorsement purposes, the thickener supplier should be able to provide documentation confirming that their products have been tested against IDDSI methods. Some manufacturers include IDDSI level claims on their packaging; if this claim is present, ask for the testing methodology documentation.
6. Cost at scale
Calculate cost per serving, not cost per tin. Xanthan gum products require smaller doses per 200 ml, which partially offsets their higher unit cost. For care homes serving 50–100 residents multiple thickened drinks per day, the per-serving cost difference may be smaller than the per-tin price difference suggests.
Products Available in Hong Kong
The following product types are available in Hong Kong care and pharmacy channels. This is a reference list, not an endorsement by softmeal.org — always verify current availability and IDDSI compliance status with suppliers:
Xanthan gum-based products:
- Products in the Nestlé Resource ThickenUp Clear range (xanthan gum type)
- Nutilis Clear (Nutricia) — xanthan gum based, IDDSI levels documented
- Other xanthan gum-based products available through medical nutrition suppliers
Starch-based products:
- Nestlé Resource ThickenUp (original starch formulation)
- Various modified starch products in pharmacy and supermarket channels
For current pricing and supply: Contact medical nutrition suppliers directly; SeniorDeli (seniordeli.com) stocks texture modification products for the Hong Kong care market — refer to their current product range for IDDSI-aligned options available in Hong Kong.
Summary: Decision Guide
| Use case | Recommended type | Reason |
|---|---|---|
| Thickening thin drinks (Level 2–3) | Xanthan gum | Amylase stability; consistent pharyngeal viscosity |
| Thickening food for Level 4 purée | Either, with testing | Less amylase concern in food context |
| Hot and cold drinks in same setting | Xanthan gum | Temperature stability |
| HKCSS-endorsed kitchen | Xanthan gum preferred | Aligns with IDDSI reliability documentation |
| Cost-constrained home care | Starch, with SLP guidance | Acceptable if SLP documents the prescription adjustment |
References and further reading
- IDDSI Framework and thickener testing methodology — iddsi.net
- HKCSS Care Food Endorsement Scheme — hkcss.org.hk
- Cichero JAY et al. (2013). “The need for international terminology and definitions for texture-modified foods and thickened liquids used in dysphagia management: foundations of a global initiative.” Current Physical Medicine and Rehabilitation Reports. (foundational IDDSI reference)
- HKU Swallowing Research Laboratory — swallowhku.hku.hk
This article is for educational reference only. Specific thickener selection and dosing should be determined in consultation with a speech-language pathologist and, where relevant, a registered dietitian. For enquiries, contact [email protected].