Pacing: The Traditional Lao Fermentation Starter

Pacing is a traditional Lao fermentation starter used primarily for the production of Lao Lao rice whisky. This small, dried cake made from rice flour and herbs represents a living microbial ecosystem containing a complex consortium of molds, yeasts, and lactic acid bacteria. Pacing is a classic example of a mixed fermentation starter, ensuring the successful saccharification and fermentation of rice. Like similar starters across Southeast Asia, including bánh men from Vietnam and loog-paeng of Thailand, pacing encapsulates generations of local knowledge and is a cornerstone of rural Lao food and beverage culture.

Cultural Roots and Naming

The Lao language refers to this starter as Pacing, while it is also known regionally as Loog-Paeng Lao or Loog-paeng lao. The culture surrounding the production of pacing is deeply entwined with animist traditions and household rituals. The process is often accompanied by incantations, a ritual called blowing rice liquor, and careful attention to seasonal timing to ensure the starter develops correctly. It is traditionally prepared by women, and the knowledge is passed down through generations, with specific family recipes being closely guarded secrets.

The Herbal Component: A Symphony of Medicinal Plants

A defining characteristic of pacing is the incorporation of various herbs and plant materials. These are not merely for flavor but serve multiple functional roles. The herbs provide antimicrobial properties that help inhibit undesirable contaminating microbes, enhance the growth of beneficial microorganisms, and contribute bioactive compounds to the final fermented product . The specific combination of herbs varies by region and family tradition, with each producer guarding their unique recipe.

Scientifically Documented Herbs Associated with Pacing and Related Starters

Based on research into pacing and its regional counterparts, the following herbs and plants have been documented for use in traditional fermentation starters:

Galangal (Alpinia galanga)

This rhizome is explicitly mentioned as being added to aid fermentation and add fragrance when making rice whiskey, which is the final product of pacing fermentation. Galangal contributes antimicrobial activity and a warm, spicy aroma that carries through to the final beverage.

Liquorice Root (Glycyrrhiza uralensis)

This root is documented as a common ingredient in a starter known as luk paeng, which is used for a similar rice spirit in the region. Liquorice root adds a subtle sweetness and is valued in traditional medicine for its anti-inflammatory properties.

Aromatic Herbs (Phak Hom)

The search results confirm that herbs, referred to locally as phak hom, are added to the rice whiskey starter to improve its fragrance. These aromatic herbs contribute complex volatile compounds that enhance the sensory profile of the final beverage.

Members of the Ginger Family (Zingiberaceae)

Plants from the ginger family, including species of Curcuma and Kaempferia, are commonly used in traditional food and medicine throughout Laos. While not explicitly named for pacing, their inclusion in related fermentation practices is well documented. These plants provide antimicrobial properties and contribute distinctive flavors.

Local Forest Tubers and Leaves

A related starter from the highlands of Laos is known to combine rice with leaves and forest tubers, pointing to a wide variety of wild plants being used. This diversity reflects the deep local knowledge of the surrounding ecosystem and the medicinal properties of indigenous flora.

Chillies, Garlic, Pepper, Ginger, and Lime Water

These ingredients are all documented as components of the luk paeng starter for a traditional rice spirit. Chillies and garlic contribute antimicrobial properties, while ginger and pepper add warmth and complexity. Lime water may adjust the pH to favor beneficial microbes.

Zanthoxylum nitidum (Toothache Tree)

This plant, also used in related starters such as Vietnam's bánh men, adds a numbing, peppery quality and is valued for its antiseptic properties. Its inclusion in pacing is consistent with the broader Southeast Asian tradition of using this plant in fermentation.

Derris elliptica

A plant used in traditional preparations for its presumed medicinal properties. Its presence in regional fermentation starters suggests it may also be used in pacing.

Piper gymnostachyum

A wild pepper species that adds mild pungency and is believed to possess antimicrobial properties. This plant is documented in related starters and is likely used in pacing preparations.

The Role of Herbs in Fermentation

The herbs and plants incorporated into pacing serve several critical functions:

Antimicrobial Protection

Many of the herbs used, including galangal, garlic, chillies, and Zanthoxylum nitidum, contain essential oils and bioactive compounds with antimicrobial properties. These help to inhibit the growth of undesirable bacteria and molds during the preparation and storage of the starter, creating a selective environment that favors the desired microbial consortium.

Microbial Stimulation

Research has shown that some herbs may provide nutrients for microbial growth. The presence of herbs has been observed to stimulate the growth of key microbes including Aspergillus rouxii and Saccharomyces cerevisiae. This enhancement of beneficial microbes contributes to the success of the fermentation.

Flavor Development

The herbs contribute complex volatile compounds that carry through to the final beverage. Galangal adds a warm, spicy note, liquorice root contributes a subtle sweetness, and aromatic herbs provide fragrance. This layering of flavors is a hallmark of traditionally produced Lao Lao.

Medicinal Properties

Many of the herbs used in pacing are also used in traditional medicine systems across Southeast Asia. Galangal, liquorice root, and members of the ginger family are valued for their anti-inflammatory, digestive, and antimicrobial properties. These medicinal compounds may be passed to the final beverage, contributing to its status as a functional food.

The Microbiology: A Diverse Consortium

Pacing contains a mixed culture of molds, yeasts, and bacteria that work in concert to convert starchy materials into fermentable sugars and subsequently to alcohol and organic acids . This community is considered more diverse than pure yeast cultures, contributing to the distinctive flavor and functional properties of the final beverage.

The major molds found in pacing include:

· Aspergillus oryzae and Aspergillus niger

· Aspergillus rouxii

· Rhizopus species, particularly Rhizopus oryzae

· Other genera such as Mucor, Actinomucor, Monascus, and Penicillium species

Saccharomycopsis fibuligera is identified as the predominant yeast in similar starters. Other yeasts that may be present include Saccharomyces cerevisiae, Pichia anomala, and various Candida species.

The bacteria present are predominantly lactic acid bacteria (LAB), including:

· Pediococcus spp.

· Pediococcus pentosaceus

· Lactobacillus spp.

LAB populations in similar starters range from 10³ to 10⁴ colony-forming units per gram. While this is relatively low compared to fermented dairy products, it still provides significant probiotic potential. The presence of LAB contributes to the tangy flavor profile, lowers the pH to inhibit spoilage organisms, and provides gut health benefits.

How Pacing Works

When pacing is mixed with cooked glutinous rice, the sequence of events is carefully orchestrated:

1. Saccharification

Molds produce amylase enzymes that break down rice starches into simple sugars.

2. Alcoholic Fermentation

Yeasts, primarily Saccharomyces cerevisiae, convert sugars into ethanol and carbon dioxide.

3. Acid Production

Lactic acid bacteria convert sugars into lactic acid, contributing to a mild tang and inhibiting spoilage.

The Peak Stage for Microbial Activity

The stage when probiotic diversity and count is at its highest is during the initial fermentation stage before the cakes are fully dried. At this point, the microbial community has fully developed and multiplied. The subsequent drying process puts the microbes into a dormant state that preserves them for long-term storage. When the dried starter is later used for rice fermentation, the microbes reactivate and reach peak counts during the fermentation process.

Environmental Factors in Pacing Production

The success of pacing production depends on careful control of environmental factors:

Moisture Content

The water content of the rice paste used to make the starter is about 50 to 55 percent. This moderately low water content is a major factor in favoring the growth of the desired molds and yeasts while inhibiting the growth of most bacteria.

Aeration

Pacing cakes are often punctured with small holes to aid aeration and promote the growth of molds and yeasts. This careful aeration ensures that the aerobic molds can establish themselves before the anaerobic fermentation begins.

Temperature

The traditional production of pacing occurs in warm, humid environments that favor the growth of the desired microbial consortium. The ambient temperature in Laos during the traditional preparation season provides ideal conditions.

Preparation Guidelines

The following represents the general principles of traditional pacing production based on documented practices. This method is intended for informational and cultural documentation purposes.

Raw Materials

Glutinous rice flour

Quantity: 500 grams. Glutinous rice is preferred for its high starch content.

Water

Quantity: As needed to form a firm, cohesive dough.

Herbal powder

Quantity: Approximately 50 grams of dried, ground herbs. The specific selection varies by region and tradition. A blend may include galangal (Alpinia galanga), liquorice root (Glycyrrhiza uralensis), aromatic herbs (phak hom), members of the ginger family (Zingiberaceae), chillies, garlic, pepper, ginger, Zanthoxylum nitidum, and other local medicinal plants.

Inoculum from a previous batch

Quantity: A few dried pacing cakes, crushed into powder. This serves as the seed culture, introducing the desired microbial consortium.

Equipment

One large, clean vessel for mixing, flat bamboo baskets for incubation, banana leaves or rice sacks for covering, and a clean surface for drying.

Pre-processing Guidelines

Grain preparation

Select high-quality glutinous rice. Grind the rice into a fine flour using a stone mill or grinder. Traditional methods involve soaking the rice in water for two hours before pounding it into a fine flour.

Herbal preparation

Collect and dry the selected herbs thoroughly. Grind the dried herbs into a fine powder using a mortar and pestle or spice grinder. The specific combination of herbs reflects the family recipe and local availability.

Inoculum preparation

Crush or grind the old pacing cakes into a fine powder. Ensure the old starter is viable and free of contamination.

Water preparation

Use filtered water free from chlorine. Chlorine will inhibit the desired microorganisms.

Vessel selection

Use clean, traditional materials such as earthenware bowls or wooden troughs. Avoid metal containers, as the acidic dough can react with some metals.

Step by Step Recipe

1. Prepare the rice flour

If using rice grains, soak them in water for two hours, then pound them into a fine flour. Alternatively, use commercially prepared glutinous rice flour.

2. Mix the dry ingredients

In a large, clean vessel, combine the rice flour and the ground herbal powder. Mix thoroughly to ensure even distribution of the herbs.

3. Add the inoculum

Sprinkle the powdered old pacing over the dry mixture. This traditional inoculation step is critical for establishing the desired microbial community. Scatter old starters or rice husks among the mixture.

4. Add water

Slowly add filtered water to the dry mixture while mixing with a clean wooden paddle or by hand. Add just enough water to form a cohesive, pliable dough. The water content of the rice paste should be approximately 50 to 55 percent.

5. Knead the dough

Knead the dough thoroughly for approximately 15 to 20 minutes until it becomes smooth and uniform.

6. Shape the cakes

Take small portions of the dough and roll them into balls approximately 3 to 4 centimeters in diameter. Alternatively, form flattened tablets or patties.

7. Perform the traditional blessing

Traditional practice involves performing the ritual of blowing rice liquor onto the new starters while uttering a charm. This is a spiritual practice to bless the starter and ensure a successful fermentation.

8. Prepare for incubation

Arrange the shaped cakes on clean bamboo mats or banana leaves, ensuring adequate spacing for air circulation. Puncture the cakes with small holes to aid aeration.

9. Incubate

Place the cakes in flat bamboo baskets. Cover the baskets with banana leaves or rice sacks. Place one large piece of old pacing per basket to provide a source of microbes. Maintain the cakes at approximately 30 degrees Celsius for about one week. During this period, the microbial community develops, and the cakes gradually dehydrate.

10. Monitor the fermentation

After three nights, blow rice liquor onto the starters again, scatter the ashes of banana leaves, and cover again for another three nights. During incubation, the cakes should develop a pleasant, earthy, fermented aroma. Any signs of contamination, such as black or green mold or unpleasant odors, indicate failure.

11. Dry the cakes

After the incubation period, allow the cakes to dry completely. Traditional methods include sun drying for two to three days or air drying in a well-ventilated area. The final moisture content should be low to preserve the starter.

12. Store

Store the dried cakes in an airtight container in a cool, dry place away from direct sunlight. Properly prepared pacing can remain viable for over a year.

Signs of Success

A properly made pacing cake is a hard, dry tablet with a pleasant, complex aroma. The color is typically off-white to light grey. When broken open, the interior should be dry and uniform. The cakes should be free of insects, mold odors, or signs of spoilage.

Troubleshooting Common Issues

Cakes develop black or green mold

Cause: Contamination by undesirable fungi due to improper environmental conditions or poor sanitation. Solution: Discard the contaminated batch. Ensure the environment is clean and the herbs are properly dried.

Cakes fail to develop mold growth

Cause: Temperature too low, insufficient humidity, or weak inoculum. Solution: Ensure the incubation room maintains the appropriate temperature and humidity. Verify that the seed culture is viable.

Cakes smell rancid or putrid

Cause: Overgrowth of undesirable bacteria. Solution: Discard the batch. This often occurs if the incubation temperature is too high or if the cakes were not properly ventilated.

Cakes are too moist after drying

Cause: Insufficient drying time or high humidity during drying. Solution: Extend the drying period or move the cakes to a drier, more ventilated area.

Storage and Shelf Life

Properly dried pacing stored in an airtight container in a cool, dry place can remain viable for over a year. The low moisture content preserves the microorganisms in a dormant state. The cakes must be protected from moisture, as rehydration can activate undesirable microbes and cause spoilage.

Usage Note

Pacing is a starter culture and is not meant to be consumed raw. To use, crush or grind the dried cakes and mix the powder into cooked, cooled glutinous rice. The microbial community will reactivate and ferment the substrate into Lao Lao, the traditional Lao rice whisky.

The knowledge of pacing making is considered a valuable part of Lao cultural heritage and is often passed down through generations within families. The specific herbal recipes are closely guarded secrets, with each family or village possessing their unique blend. This diversity contributes to the rich tapestry of Lao fermented beverages and represents a living tradition of microbial domestication.

-x-x-