Pak-gard-dong (salt-then-sugar method)

A mustard ferment built around two stages

This record describes a third documented preparation, distinguished by the order in which salt and sugar are added.

The method begins with washed, wilted mustard leaves.

Salt equal to 2.5% of the wilted vegetable weight is mixed into the leaves. They are packed and held for 12 hours.

The resulting salty liquid is removed.

Sugar equal to 3% of the wilted vegetable weight is then added, and the vegetables undergo further fermentation for 3–5 days at room temperature.

The final result is a fermented mustard vegetable with a sour, salty character.

Unlike the high-salt version in record veg-0015, this process removes the first liquid rather than retaining the full salt addition in a densely packed vegetable mass.

Unlike the sweet rice-wash version in record veg-0016, it does not require a large added brine or a cup of palm sugar.

It is a distinct traditional process with its own salt treatment, microbial conditions and flavor development.

History and source tradition

Pak-gard-dong is included in scientific surveys of traditional Thai fermented foods.

The particular salt-then-sugar method was described in earlier Thai food research attributed to Boon-Long in 1986 and summarized in Fermented Foods and Beverages of the World, published in 2010.

The scientific literature also identifies earlier microbiological work by Mingmuang in 1974.

These dates document research and publication, not invention of the product.

The recipe is part of Thailand's wider preserved-mustard tradition, which has connections with similar foods across mainland Southeast Asia.

The precise historical relationship between the three preparation methods in this collection is unknown.

There is no secure basis for saying the dry-salted, rice-wash or salt-then-sugar method developed first.

What can be established is that all three were recognized in technical descriptions of traditional Thai vegetable processing.

This method's distinctive feature is its explicit separation of the preliminary salting stage from the later sugar-assisted fermentation.

Recipe overview

Vegetable — Black mustard leaves

Salt — 2.5% of wilted vegetable weight

Preliminary salting — 12 hours

Sugar — 3% of wilted vegetable weight

Main fermentation — 3–5 days

Temperature — Room temperature; no numerical value given

Added water — None specified

Finished yield — Not specified

Shelf life — Not validated by this recipe description

Ingredients

Black mustard leaves — As required; no fixed batch weight

Salt — 2.5% of wilted vegetable weight

Sugar — 3% of wilted vegetable weight

The recorded method does not specify the type of sugar.

It also does not give a recipe-specific amount of water.

A separate account of pak-sian-dong, a different Thai fermented vegetable, mentions raw cane or palm sugar. That preference must not be transferred automatically to pak-gard-dong.

The correct ingredient listing here is simply sugar.

Choosing the mustard greens

The published description refers to black mustard leaves.

The broader preserved-mustard family includes plants identified as Brassica juncea.

Mustard varieties differ in leaf size, petiole thickness, moisture content and pungency.

The preparation should use the edible mustard leaves intended by the regional technique rather than assuming any vaguely similar brassica will behave identically.

Leaves with extensive decay or damage are unsuitable.

Stems and leaves may require different handling because thick tissue loses water more slowly than thin leaf blades.

The original process does not specify whether large stalks are split, chopped or retained intact.

That uncertainty should be preserved.

Salt and its role

The first addition is calculated from wilted vegetable weight.

This detail matters because wilting reduces mass by removing water.

If the same salt percentage were calculated from fresh vegetable weight, the actual amount added after wilting might differ significantly.

The salt draws liquid from plant tissues.

It also changes the microbial environment.

At a moderate concentration, salt can favor salt-tolerant lactic acid bacteria over some competitors.

The first stage is therefore both a physical conditioning treatment and the beginning of microbiological selection.

The 12-hour holding period allows water and dissolved compounds to move out of the leaves.

The salty liquid is then removed.

This discarded liquid contains an unknown portion of the original salt addition.

The finished product cannot be assigned a final salt percentage of 2.5% without measurement.

Why the sugar comes later

The method adds sugar only after the preliminary salty liquid has been removed.

That means the first stage principally conditions the vegetable and redistributes salt.

The second stage introduces additional fermentable carbohydrate.

Lactic acid bacteria can metabolize available sugars into lactic acid.

As acid accumulates, sourness develops.

The sequence differs from recipes in which all sugar and salt are added together at the beginning.

It may affect which microorganisms proliferate and how rapidly acid forms, although the precise effect is not quantified in the source.

The original description does not provide a comparative experiment showing that the two-stage method is microbiologically superior.

It should be understood as a documented traditional procedure, not an experimentally proven optimal schedule.

Equipment

Use a clean washing container, a suitable surface for wilting, a scale capable of weighing ingredients and a clean food-grade fermentation vessel.

The recorded method does not specify a particular vessel volume or shape.

Because the ingredients are given as percentages, accurate weighing is important.

Use a safe cover or fermentation arrangement that limits contamination while allowing gas pressure to be managed.

Method

1. Select the leaves.

Remove defective or deteriorated mustard leaves.

The original procedure refers specifically to black mustard leaves.

Do not include obviously decayed plant material.

2. Wash thoroughly.

Clean the leaves to remove soil and grit.

Drain excess water.

The recorded method does not give a specific number of rinses.

3. Wilt in sunlight.

Spread the leaves in the sun until they become wilted.

The exact wilting duration is not stated in the summarized method.

No target moisture content or percentage weight reduction is provided.

4. Weigh the wilted vegetables.

The salt and sugar percentages are expressed against the wilted weight.

Record that weight before calculating the additions.

This avoids confusing fresh-vegetable and wilted-vegetable mass.

5. Add the salt.

Use salt equal to 2.5% of the wilted leaf weight.

Distribute it across the leaves, including folds and thick sections.

The recorded method does not describe a separate added-brine solution.

6. Pack and rest.

Place the salted vegetables into a suitable container.

Hold for 12 hours.

During this stage, salt draws out vegetable moisture.

7. Remove the salty liquid.

Drain off the liquid released during the preliminary stage.

The recorded method does not specify squeezing pressure, rinsing or washing after this stage.

Do not add an unrecorded rinse step and present it as part of the historic method.

8. Add sugar.

Mix sugar equal to 3% of the original wilted vegetable weight into the drained mustard.

Distribute it as evenly as possible.

The method does not give a sugar type or the concentration of dissolved sugar after mixing.

9. Ferment.

Return the vegetables to their container and ferment at room temperature for 3–5 days.

No numerical room temperature is given.

The historical description also lacks a validated final acidity or microbial safety endpoint.

10. Assess and use.

The intended result is fermented mustard greens with characteristic sourness.

Do not infer shelf stability solely from the passage of three to five days.

Use suitable food-safety controls and storage conditions.

How the microbial succession develops

Lactic acid bacteria are central to the process.

The technical literature identifies Pediococcus pentosaceus, Lactobacillus brevis and Lactobacillus plantarum as important organisms associated with this Thai mustard fermentation.

These organisms have different metabolic properties.

Pediococcus pentosaceus can produce lactic acid from available carbohydrates.

Lactobacillus brevis, now generally classified as Levilactobacillus brevis, is heterofermentative and may produce additional metabolites alongside lactic acid.

Lactobacillus plantarum, now commonly Lactiplantibacillus plantarum, can grow in a range of vegetable-fermentation environments.

The exact microbial order is not established for every household batch.

The process probably begins with the organisms present on the leaves and in the handling environment, rather than a deliberately added pure starter.

As the chemical environment changes, organisms that tolerate the available salt and acidity can become more competitive.

Acid production may inhibit some unwanted microbes, but this effect depends on how quickly sufficient acidity develops.

Biochemical changes in mustard greens

Mustard greens contain glucosinolates and the enzyme myrosinase.

When plant tissue is damaged, enzyme and substrate can interact, generating compounds associated with pungent mustard aroma.

Wilting, salting and fermentation can alter these compounds.

Some may diffuse into the liquid released during the preliminary salt treatment.

Others may undergo chemical or microbial transformations.

These processes help explain why fermented mustard greens taste different from freshly cooked leaves.

Salt also changes texture by affecting water distribution.

As the leaves become less turgid, they can be packed more closely.

During fermentation, organic acids develop and vegetable pigments may become less vivid.

The finished product is therefore altered by a sequence of physical, chemical and microbial processes.

Why removing the first liquid is significant

Discarding the salty liquid removes more than water.

It can remove some salt, soluble sugars, bitter compounds and other small molecules.

This changes the substrate available during the later fermentation.

The effect may be desirable for flavor, especially where the original mustard leaves are strongly bitter.

However, the exact concentration of each removed compound has not been measured in the cited process.

The technique should not be represented as a validated method for removing any particular toxin or antinutrient.

It is a distinctive stage of the recorded preparation.

Regional comparison

The wider Thai family includes several methods.

The dry-salted JIRCAS version adds 8–10% salt and a small amount of cooked rice, then ferments for 5–10 days.

The sweeter JIRCAS version uses salt, palm sugar and rice-wash water, fermenting for 3–5 days.

This salt-then-sugar process uses 2.5% salt, a 12-hour preliminary rest and 3% sugar.

The different percentages and liquid-management stages produce substantially different starting conditions.

These are not small seasoning substitutions.

The name pak-gard-dong therefore describes a family of preserved mustard greens rather than a single uniform manufacturing standard.

Culinary use

The resulting greens can be served with rice or used as a cooking ingredient.

Thai preserved mustard greens appear in soups, noodle dishes and meals containing braised pork.

They provide sourness and a preserved vegetable character.

Chopped preserved greens can also be cooked with egg.

The actual amount to use in a dish depends on the finished product's salt and acidity.

Because the original process does not specify a final salt concentration, cooks should not assume that all pak-gard-dong products season a dish identically.

A particularly salty product may require washing before cooking, while a less salty sour version may contribute more acidity.

Signs of successful processing

The expected outcome is wilted, preserved mustard leaves that develop a characteristic sour flavor.

The vegetables should remain recognizable rather than decompose into a slimy mass.

Some color change from bright green is normal during processing.

However, the recorded method does not provide a validated sensory acceptance scale.

Fuzzy mold, abnormal decomposition odors, visible infestation or unexpected heavy slime indicate problems.

A sour smell alone is not proof of microbiological safety.

Likewise, a correctly weighed salt addition does not guarantee that acidification will proceed at the same rate in every vessel.

Safety and storage

The original technical description provides salt percentage, sugar percentage, the preliminary resting time and fermentation duration.

It does not provide a final pH, microbial challenge study, temperature range, water activity or validated storage time.

The general pH 4.60 threshold used in produce-fermentation safety guidance cannot be assumed to have been reached without measurement.

A modern commercial process requires controls for vegetable washing, salt distribution, fermentation temperature, acidity and packaging.

Because some of the salty liquid is drained away, calculating the final salt concentration requires more information than the original ingredient percentages.

This should remain a historically documented method until its operating conditions have been validated for the intended production setting.