Herbal Quality Assessment: What Raw Herbs Can Tell Practitioners

Beyond the Label: What the Raw Herb Can Tell Us About Quality

By Dr Simon Feeney

When a practitioner orders Huang Qi, Bai Shao or Chen Pi, the name on the label may remain the same from one batch to the next. The material inside the package, however, is not automatically identical.

Herbs are agricultural materials. Their characteristics can be influenced by species, plant part, growing region, climate, soil, cultivation practices, harvest timing, processing, drying, transport and storage. Even when two batches are correctly identified, they may differ in appearance, aroma, texture and overall condition.

For practitioners, this raises an important question:

How much can we learn by looking closely at the herbs we prescribe?

The answer is both more and less than we might expect.

Direct observation cannot confirm everything. A practitioner cannot reliably determine pesticide residues, heavy metals, microbial contamination or chemical composition simply by looking at a herb. Those questions require appropriate documentation and, where relevant, validated laboratory testing.

What sensory assessment can do is help us recognise whether material appears consistent with what we expect, notice changes between batches and identify reasons to pause and ask further questions.

The goal is not to turn every practitioner into a pharmacognosist. It is to remain engaged with the material itself.

Quality Is Not a Single Characteristic

In everyday conversation, we often describe a herb as either “good quality” or “poor quality”. In practice, quality is multidimensional.

The Therapeutic Goods Administration identifies a range of factors that may influence the quality of herbal raw materials, including:

• Botanical characteristics and the plant part used
• Phytochemical characteristics
• Biological and geographical variation
• Cultivation, harvesting and drying conditions
• Microbial levels, aflatoxins and toxic elements
• Pesticides, fumigants and other pre-harvest or post-harvest treatments
• The stability and profile of relevant constituents

This is why no single test, certificate or physical characteristic provides the complete answer.

A herb may be correctly identified but poorly stored. It may look visually impressive but contain unacceptable contaminants. It may meet a chemical marker specification while being the wrong plant part for the intended material.

A more useful approach is to think of quality as several connected layers.

1. Identity

Is the material the correct botanical species, plant part and processed form?

2. Purity and safety

Has the material been assessed for relevant contaminants, adulterants and foreign matter?

3. Condition

Has it been harvested, dried, transported and stored in a way that preserves its expected characteristics?

4. Consistency

Is the current batch reasonably consistent with authenticated reference material and previous accepted batches?

5. Traceability

Can the supplier provide meaningful information about where the material came from and how it was handled?

For practitioners, the visible herb is an important part of this picture, but it is not the whole picture.

Start With the Correct Identity

Before considering whether a herb appears vibrant, aromatic or well preserved, we need to know that it is the correct material.

A complete identity is more specific than a common or pinyin name. It should account for:

• The accepted botanical name
• The plant part used
• The form supplied
• Any relevant processing method

This distinction matters because a single common name may be associated with more than one botanical source. Different parts of the same plant may also have different identities and uses.

Processing adds another layer. Prepared forms such as Zhi Ban Xia, Shu Di Huang or Zhi Gan Cao should not be treated as interchangeable with their unprocessed counterparts. Processing may intentionally alter the material’s physical and chemical characteristics.

Macroscopic and microscopic examination, chemical fingerprinting and DNA-based methods can all contribute to authentication. Each has strengths and limitations.

For example, DNA testing can assist with species identification when suitable genetic material remains available. However, it does not determine the concentration of relevant constituents, identify all contaminants or necessarily distinguish between different plant parts. Processing may also degrade DNA and make some finished materials difficult to assess using genetic methods alone.

Good authentication therefore relies on complementary evidence rather than one test being expected to answer every question.

What Practitioners Can Observe

Macroscopic or sensory examination involves characteristics that can be assessed with the senses, principally sight, smell and touch. Taste may form part of formal traditional identification, but practitioners should not casually taste unfamiliar or potentially toxic materials.

The value of sensory examination comes from comparison. A single characteristic viewed in isolation is rarely conclusive. Patterns across multiple characteristics are more informative.

1. Shape, Size and Plant Structure

Begin by asking whether the material resembles the plant part described on the label.

Roots, rhizomes, bark, stems, leaves, flowers, fruits and seeds each have characteristic structures. Depending on the herb, useful observations may include:

• The shape and thickness of slices
• The appearance of the outer surface and cut face
• Growth rings, fibres, oil points or vascular patterns
• The relationship between skin, cortex and central tissues
• The proportion of broken material, dust or fragments
• Whether the expected plant part is clearly recognisable

These observations can help identify gross inconsistencies, excessive fragmentation or the presence of unexpected material.

They are most useful when compared with authenticated samples, pharmacopoeial descriptions or well-documented material from a trusted supplier.

2. Colour

Colour can provide information, but it is easily overinterpreted.

Unexpected fading, darkening, bleaching, spotting or unevenness may warrant further attention. Colour can be influenced by age, oxidation, moisture, drying conditions, processing and storage. It may also vary naturally according to growing conditions and the part of the plant examined.

A brighter colour is not automatically better. Some materials are naturally muted, while some treatments may make herbs appear unusually pale, clean or uniform.

Rather than asking, “Is this colour good?”, it is often more useful to ask:

• Is the colour typical for this herb and processed form?
• Is it consistent throughout the batch?
• Has it changed noticeably from the previous batch?
• Is there staining, spotting or discolouration that could indicate deterioration?
• Does the material appear unnaturally bleached or visually uniform?

Colour should trigger investigation when it differs from expectation. It should not be used alone to accept or reject a batch.

3. Aroma

Aroma is one of the fastest ways to notice change in aromatic herbs.

When appropriate, place a small amount of the herb in a clean container and assess it away from strong ambient smells. Gently breaking or rubbing a suitable piece may release volatile compounds and make the aroma easier to recognise.

Consider:

• Is the expected aroma present?
• Is it unusually weak?
• Does it smell musty, sour, stale, smoky or chemically treated?
• Is the aroma consistent with previous accepted batches?

A weak aroma may reflect age, extended storage, poor sealing or loss of volatile compounds, but it does not prove any single cause. Conversely, a strong aroma is not sufficient evidence of identity or purity.

The most valuable comparison is often with a retained sample from a previous batch.

4. Texture and Moisture

Touch can reveal whether a dried herb is crisp, fibrous, pliable, sticky, oily, brittle or unusually soft.

Again, the expected texture depends on the material. Some dried fruits and prepared herbs naturally retain more flexibility or stickiness than roots and barks.

Changes worth investigating include:

• Unusual dampness or softness
• Excessive brittleness or powdering
• Clumping
• A tacky surface where this is not expected
• Visible condensation within packaging
• Loss of the herb’s usual structural character

Moisture matters because it can affect stability and create conditions that support microbial growth. However, accurate moisture content or water activity cannot be determined by touch alone. If a concern arises, it requires appropriate testing and investigation.

5. Cleanliness and Foreign Matter

Examine the material for anything that does not belong.

This might include:

• Soil, stones or other field matter
• Unrelated plant material
• Excessive stems or unwanted plant parts
• Insect damage, webbing or larvae
• Visible mould
• Uncharacteristic dust or debris
• Packaging fragments

Agricultural materials will not always look mechanically perfect, and some natural variation should be expected. The question is whether the material falls within an appropriate specification and whether any foreign matter creates a quality or safety concern.

If mould, active insect infestation or unexplained contamination is suspected, isolate the material and contact the supplier. Do not simply remove the affected pieces and dispense the remainder.

What the Senses Cannot Confirm

Sensory familiarity is valuable precisely because it helps us recognise when further investigation is needed. It should never be confused with laboratory analysis.

You cannot reliably determine the presence or acceptable level of the following by appearance, smell or texture alone:

• Pesticide residues
• Heavy metals
• Aflatoxins
• Pathogenic microorganisms
• Undeclared chemical treatments
• Sulphur dioxide residues
• The concentration of marker compounds
• Substitution that closely resembles the expected species

Sulphur fumigation is a useful example. It has historically been used to discourage insects, inhibit mould and improve the appearance of some herbal materials. Research has demonstrated that it can also alter chemical profiles in certain herbs.

An unusually pale appearance or sharp odour might prompt questions, but sensory examination cannot confirm whether fumigation occurred or quantify any residue. That requires suitable analytical testing.

The practical lesson is not to distrust the senses. It is to understand their limits.

Build a Simple Receiving Check Into the Dispensary

Practitioners do not need an elaborate laboratory system to become more attentive to incoming herbs. A brief, consistent receiving process can make changes easier to notice and document.

When a new batch arrives:

Confirm the label

Check the herb name, botanical identification where provided, plant part, processed form, batch number and expiry or retest information.

Inspect the packaging

Look for damage, broken seals, moisture, contamination or signs of pest activity.

Observe the material

Compare its shape, colour, aroma and texture with what you reasonably expect.

Compare batches

If possible, retain a small, clearly labelled reference sample from the previous accepted batch. Compare like with like, including the same processed form.

Record significant differences

Take clear photographs and note the batch number, date and observation. Avoid relying on memory alone.

Isolate questionable material

If something appears inconsistent or compromised, separate it from usable stock while you seek clarification.

Ask the supplier

Provide the batch number, photographs and a specific description of the concern. A precise question is more useful than simply saying the herb “does not look right”.

Download our one-page Incoming Herb Check to use when receiving raw herbal materials. It provides a simple framework for recording batch details, checking the material and documenting any concerns before it enters your dispensary.

Download the Incoming Herb Check PDF

Better Questions to Ask a Supplier

A reliable supplier should be able to provide more than a product name.

Depending on the herb and format, useful questions may include:

1. What is the full botanical identity and plant part?
2. What is the country or region of origin?
3. Is the herb cultivated or wild collected?
4. How has it been processed?
5. What authentication methods are used?
6. What batch testing is conducted?
7. Can relevant certificates of analysis be supplied?
8. How is the material protected during storage and transport?
9. How are supplier or batch changes managed?
10. What process is followed when a practitioner raises a quality concern?

Not every answer needs to appear on the retail label. It should, however, exist within the supply chain.

Keep a Small Reference Library

One of the most practical ways to build familiarity is to create a small internal reference collection.

Retain representative samples from accepted batches in clean, airtight, clearly labelled containers. Record:

• Herb name
• Botanical identity
• Plant part
• Processed form
• Supplier
• Batch number
• Date received
• Country or region of origin, if available
• Notes on appearance, aroma and texture

Photographs are helpful, but they cannot fully capture aroma, density or texture. A physical sample allows future batches to be compared more meaningfully.

Reference samples also need appropriate storage. Light, heat, moisture, oxygen and pests can change the sample over time, so an old reference should not be treated as a permanent ideal.

The aim is to build familiarity and track change, not to create an infallible standard.

The Practitioner’s Role

Practitioners should not be expected to reproduce the quality systems of a manufacturer or analytical laboratory. We can, however, remain active participants in the chain of quality.

That means knowing what we are ordering, examining what arrives, maintaining suitable storage conditions, recording unexpected changes and asking informed questions.

It also means accepting uncertainty.

Natural variation is not automatically evidence of poor quality. Visual appeal is not proof of purity. A certificate is only meaningful when it relates to the correct material and batch, and when the methods and specifications are appropriate.

The most reliable decisions come from multiple forms of evidence working together:

• Authentic botanical identity
• Traceable sourcing
• Appropriate specifications
• Relevant analytical testing
• Careful handling and storage
• Familiarity with the physical material
• Clear communication between practitioner and supplier

Look, Compare, Document and Ask

The raw herb still has something to teach us.

Its shape, aroma, texture and condition can help us recognise consistency, identify unexpected changes and decide when further investigation is warranted. These observations do not replace scientific testing. They make us better users of it.

The next time a new batch arrives, take a moment before placing it on the shelf.

Look closely. Compare it with what you know. Record anything unusual. Ask questions when the material differs from expectation.

The closer we remain to the herbs themselves, the more informed our decisions can become.

Practical Takeaways

• Treat quality as a combination of identity, purity, condition, consistency and traceability.
• Confirm the botanical identity, plant part and processed form.
• Use sight, smell and touch to compare material with authenticated references and previous batches.
• Do not assume brighter colour, stronger aroma or larger size automatically means better quality.
• Remember that contaminants and chemical composition cannot be reliably assessed by the senses.
• Keep batch records, photographs and small reference samples where practical.
• Isolate questionable material rather than dispensing it while an issue remains unresolved.
• Ask suppliers specific questions and request batch-relevant documentation.

References

1. Therapeutic Goods Administration. Understanding the application requirements for a new substance for use in listed medicines. Australian Government.

2. European Medicines Agency. Guideline on quality of herbal medicinal products/traditional herbal medicinal products.

3. Abubakar BM, Salleh FM, Wagiran A. DNA barcoding and chromatography fingerprints for the authentication of botanicals in herbal medicinal products. Evidence-Based Complementary and Alternative Medicine. 2017.

4. Zhu S, et al. DNA barcoding: an efficient technology to authenticate plant species of traditional Chinese medicine and recent advances. Chinese Medicine. 2022.

5. Xu W, et al. Sulphur fumigation of botanical drugs: impact on chemical composition, pharmacological activity and quality assessment. 2025.

6. Kan WLT, et al. Sulphur fumigation processing of traditional Chinese medicinal herbs: beneficial or detrimental? Frontiers in Pharmacology. 2011.

This article is intended for educational purposes for practitioners and students of Chinese medicine. It does not replace applicable professional, regulatory, dispensing or quality assurance requirements.