Choosing and Buying Casings for Thai Sausages

Most Thai sausages are best made in natural hog casings. These are cleaned pig intestines, roughly 28–38 mm in diameter. They give a thin, translucent skin that blisters and snaps over charcoal. Northern Thai sai ua usually goes into medium hog casings and is coiled into a spiral. Isan's sour sai krok Isan is often made in narrower casings and twisted into small, plump links. Edible collagen casings are an easier backup when natural ones are hard to find. Sheep casings suit thin snack-sized sausages. Plastic and fibrous casings are not suitable, because Thai sausages are eaten skin and all.

What are Thai sausage casings?

A sausage casing is the tube that holds the seasoned meat filling together during sausage stuffing, cooking and serving. For Thai sausages, the casing is part of the eating experience. When grilled, it turns from pale and soft to golden, crackly and slightly chewy. It seals in juices and the aromatic paste of lemongrass, galangal, garlic and chili.

Thai sausage casings fall into two practical groups.

• Natural casings are cleaned animal intestines, mostly from pigs, sometimes from sheep. They are the traditional choice in Thailand.
• Collagen casings are manufactured from animal collagen and shaped into uniform tubes. They are an edible, more standardized alternative.

Natural hog casings

Natural hog casings are the standard casing for sai ua and sai krok Isan.

• Raw look and feel: slightly translucent and off-white to pale ivory, with faint lines and an uneven, organic width. They feel slippery and stretchy.
• Smell: they usually arrive packed in salt or brine and smell salty and faintly animal. Most of that smell disappears after rinsing and soaking.
• Cooked result: the casing tightens around the filling and turns glossy and amber-brown. Over charcoal it blisters in spots and bites with a clean snap.

Because each casing comes from a real intestine, the width varies a little along its length. This is why homemade sai ua looks slightly irregular, which is part of its charm.

Natural sheep casings

Sheep casings are narrower and more delicate than hog casings, typically around 20–26 mm in diameter. They are very thin and tender. They work for thin, finger-sized Thai-style snack sausages, but they tear more easily during stuffing. They also give a less robust, rustic look than hog casings.

Collagen casings

Edible collagen casings are uniform tubes, often sold compressed ("shirred") into stiff, pleated sticks.

• Appearance: they look like even, matte or slightly glossy tubes, often pale or lightly tinted. They have none of the natural lines of intestine.
• Handling: they need no rinsing or soaking unless the manufacturer says otherwise. They are quick to load onto a stuffing horn.
• Cooked result: they give a tender, even bite with less snap than natural casings. They also blister less dramatically on the grill.

Natural vs collagen casings: which is better for Thai sausages?

Natural hog casings give the most authentic texture and look for Thai sausages. Collagen casings are easier to store and handle. The table compares them on the points that matter most for sai ua and sai krok Isan.

Feature	Natural hog casings	Edible collagen casings
Bite after grilling	Pronounced snap, slightly chewy	Tender, softer snap
Look	Rustic, slightly irregular, blistered	Smooth, uniform, factory-even
Twisting into links	Holds twists well, good for sai krok's small balls	Twists can loosen; tying with string is more reliable
Coiling (sai ua spiral)	Flexible and easy to coil	Possible, but stiffer and more prone to splitting at tight bends
Preparation	Rinse, soak and flush before use	Usually ready to use straight from the pack
Storage	Refrigerated, packed in salt or brine	Dry, cool cupboard (check the label)
Traditional for Thai sausages	Yes	No, a modern substitute

For a first batch of sai ua, collagen casings are a forgiving way to practise. If you want the crackly, blistered skin you see on grills at Thai markets, natural hog casings are worth the extra preparation.

Which casing diameter suits each Thai sausage?

Casing diameter is the width of the filled casing, measured in millimetres (mm). Suppliers sell different size sausage casings in ranges such as 32–35 mm or 35–38 mm. The right range depends on the sausage style.

Thai sausage	What it is	Common casing choice	Typical shape
Sai ua (Northern Thailand)	Herb-packed pork sausage, yellow-orange from turmeric and red curry-style paste. It smells strongly of lemongrass and makrut lime leaf.	Medium natural hog casings, often in the low-to-mid 30s mm range	One long rope, coiled into a flat spiral and grilled whole
Sai krok Isan (Northeastern Thailand)	Pork, garlic and cooked sticky rice, left to ferment until pleasantly sour. It is pale pink-white inside.	Narrower hog casings, around the lower end of the hog range or slightly smaller	Short, round or oval links, often tied in chains like beads
Thin snack-style Thai sausages	Thinner sausages for skewers or quick grilling	Sheep casings or small-diameter collagen casings	Thin, finger-length links

Width ranges vary between regions, recipes and suppliers, so treat them as a starting point rather than a rule. A wider casing gives a juicier interior but needs longer, gentler grilling so the centre cooks through before the skin burns. A narrower casing cooks faster and gives a higher ratio of crisp skin to filling.

How to recognize good sausage casings when buying

Good natural casings look clean, pale and evenly translucent, and smell only of salt and a faint animal note. Use these checks when buying natural casings.

• Colour: creamy white to light ivory. Avoid casings that look grey-green, have dark spots, or seem slimy beyond the normal slipperiness.
• Smell: salty and mild. A sour, rotten or ammonia-like smell means the casings have spoiled.
• Packing: salted casings should be fully covered in salt. Brine-packed casings should sit in clear or slightly cloudy liquid, not murky or foul-smelling liquid.
• Label information: look for the animal (hog or sheep), the diameter range in mm, and the length or stuffing capacity.

For collagen casings, check that the package is sealed. Make sure the casings are labelled edible, and that the diameter suits your sausage. Inedible collagen and fibrous casings look similar on the shelf but are made for products that are peeled before eating, such as some salamis.

Where to find sausage casings to buy

You can find sausage casings to buy at butcher shops, Asian supermarkets, sausage-making and butchery supply shops, and online suppliers. Each source has its own strengths.

• Local butchers: many butchers who make their own sausages will sell a small quantity of hog casings if you ask. This is often the easiest way to buy just enough for one batch.
• Asian grocery stores: some stock salted or frozen hog casings, usually in the refrigerated or freezer section near pork products.
• Butchery and sausage-making suppliers: these offer the widest choice of natural and collagen casings in clearly labelled diameter ranges.
• Markets in Thailand: fresh pork stalls may sell cleaned pig intestines for sausage-making. Outside Thailand, packaged salted casings are far more common.

How casings are packaged

Natural casings are sold in a few common formats.

• Dry-salted: casings are packed in coarse salt. They keep well in the refrigerator and are the most common format for home cooks.
• In brine: casings sit in salty liquid and need less soaking. They are often sold in tubs.
• Hanks: a traditional bulk bundle of a fixed total length, used by butchers. It is usually far more than a home cook needs.
• Pre-tubed or pre-flushed: the casings are threaded onto a plastic sleeve, so they slide onto the stuffing horn quickly and tangle less.

How much casing do you need?

The amount of casing you need depends on the weight of filling and the casing diameter. Wider casings hold more meat per metre. Supplier labels usually state the approximate weight of filling a pack can hold, and following that figure is more reliable than guessing. Buy a little extra, because natural casings sometimes have weak spots or holes and you may need to cut and restart.

How to prepare natural casings before stuffing

Natural hog casings must be rinsed, soaked and flushed before stuffing to remove salt and make them soft and stretchy. Follow these steps.

1. Take out slightly more casing than you think you need and return the rest to its salt.
2. Rinse the outside under cool running water to remove loose salt.
3. Soak the casings in a bowl of lukewarm water until they feel soft and supple. Follow the timing on the package, as it varies between salted and brined products.
4. Open one end, slip it over the tap and run water gently through the inside. This flushes out salt and reveals any holes, which show up as small leaking jets.
5. Cut out sections with holes, then keep the casings in fresh water until you are ready to stuff.
6. Slide a length of casing onto the stuffing horn, leaving a short tail at the end before tying it off.

When stuffing, fill the casing firmly but not to bursting. Leave a little room so sai krok can be twisted into links and sai ua can bend into a coil without splitting. Prick visible air pockets with a clean needle or sausage pricker.

Matching casings to kitchen tools

The stuffing horn (the nozzle on a sausage stuffer or mincer attachment) must be narrower than the casing so the casing can slide on easily.

• Sausage stuffer: a piston or crank stuffer gives the most even, air-free fill. Most come with several horn sizes.
• Mincer attachment: many meat grinders have a stuffing tube. They work for small batches but can warm and smear the filling.
• Kitchen string: useful for tying the chain of small sai krok links, especially in collagen casings that do not hold twists well.

Use a medium horn for medium hog casings, and a small horn for sheep casings and thin collagen casings. A horn that is too thick will tear delicate casings. A horn that is too thin slows stuffing and can trap air.

Substitutes when you cannot find casings

If no suitable casings are available, you can still enjoy the flavours of Thai sausages, with some trade-offs.

• Collagen instead of natural casings: this is the closest substitute. Expect a softer bite and a more uniform look.
• Sheep instead of hog casings: this gives thinner, quicker-cooking sausages. They tear more easily and feel less hearty than classic sai ua.
• Casing-free patties: you can shape sai ua filling into flat patties and pan-fry or grill them. You keep the herbal aroma of lemongrass, galangal and makrut lime but lose the snap and the juicy, sealed interior. The patties also dry out faster.
• Not suitable: plastic and inedible fibrous casings. They do not soften or crisp into an edible skin, so they defeat the point of a grilled Thai sausage.

Sai krok Isan is the hardest to substitute. Its sour flavour develops as the filling ferments inside the casing, so casing-free versions are not the same dish.

How to store leftover casings

Store unused natural casings packed generously in salt in a sealed container in the refrigerator. Stored this way, salted casings stay usable for a long time. Check the supplier's guidance for the exact period. Never refreeze casings that have already been thawed and soaked. Keep collagen casings dry in their original packaging in a cool place, away from humidity. Moisture can make them sticky and weak.