The U.S. hemp-derived cannabinoid market is approaching a significant regulatory change. For manufacturers of gummies and other edibles, the immediate questions are understandably about cannabinoid composition, THC limits, ingredients and whether existing products can continue to be marketed. But if a gummy has to be reformulated, there is another question that deserves just as much attention: will the new formulation still have the same microbial, physical and chemical stability as the product it replaces?

Changing a cannabinoid extract, carrier, sweetener, humectant, gelling system, drying process or package can change how water behaves inside a gummy, even when total moisture appears similar. Water activity, or a_w;, provides a practical way to evaluate that moisture environment and can help manufacturers control mold and yeast risk, texture, moisture migration and overall shelf-life stability.

WHAT IS ACTUALLY CHANGING IN THE U.S. HEMP MARKET?

Federal law enacted in November 2025 changes the statutory definition of hemp. Instead of relying only on the previous limit of 0.3% delta-9 THC on a dry-weight basis, the amended definition uses total THC, including THCA, and introduces exclusions for specific intermediate and final hemp-derived cannabinoid products. For final hemp-derived cannabinoid products, one of the new exclusions applies above 0.4 mg combined total per retail container of total THC and other cannabinoids with similar effects. [1,2]

The implementation timeline has also changed. The amendments were originally scheduled to take effect on November 12, 2026. Following Public Law 119-103, most of the new definition is now scheduled to apply from December 11, 2026. A narrower exclusion covering intermediate and final products containing cannabinoids that are not capable of being naturally produced by Cannabis sativa is still scheduled to apply from November 12. As of its September 28 update, the Congressional Research Service also reported that FDA had not yet published the cannabinoid lists and additional clarification on the term “container” required by the 2025 legislation. [1,3]

This remains a moving regulatory environment, and federal hemp status is only one part of the picture. State requirements can be substantially different. California, for example, has required since January 2026 that industrial hemp extract used in foods, beverages and dietary supplements contain no THC or synthetic cannabinoids, subject to its own requirements for CBD and CBN ingredients. [5]

FDA food law is another separate issue. FDA continues to state that introducing conventional food containing added THC or CBD into interstate commerce is prohibited under the current Federal Food, Drug, and Cosmetic Act framework. Manufacturers therefore need to consider federal hemp classification, FDA requirements and applicable state laws separately. [4]

WHY DOES THIS MATTER FOR WATER ACTIVITY?

The regulatory change itself is not a water activity regulation. The connection arises when manufacturers change their products in response to it. A gummy is a complex matrix containing water, sugars or polyols, gelatin or pectin, acids, flavors, oils, extracts and other active ingredients. Each of these components interacts with water differently. Changing an extract or carrier, replacing sugar, altering the gelling system or adjusting drying time can therefore change a_w even when the final product looks almost identical.

That matters because a_w describes the thermodynamic availability of water, rather than simply how much water is present. This available water influences microbial growth, moisture migration, texture and many chemical and physical stability mechanisms. Novasina’s work with gummies and other functional foods therefore uses a_w as one of the central parameters for balancing microbial stability, texture, stickiness, hardening and shelf life. [7,8]

For a manufacturer that already has a successful product with twelve or eighteen months of stability data, this creates a useful opportunity. The established product’s normal a_w range can become part of its stability fingerprint. If regulatory changes require reformulation, the new product can then be compared against that known starting point.

HOW CAN a_w HELP CONTROL MOLD AND YEAST?

This is one of the strongest applications of water activity in cannabis products. Microorganisms respond to the availability of water rather than simply the percentage of water contained in the product. As a_w decreases, fewer microorganisms remain capable of growing.

For dry cannabis flower, this relationship is sufficiently well established that ASTM D8197 specifies an a_w range of 0.55 to 0.65. ASTM states that a_w should remain below 0.65 to protect against undesirable microbial growth such as mold, while remaining above 0.55 helps prevent physical damage associated with excessive drying. [6]

Gummies are different. Their microbial stability typically depends on several hurdles working together, including a_w, pH, preservatives, heat treatment, hygienic manufacturing and packaging. Consequently, an a_w value that is appropriate for cannabis flower should not simply be copied into a gummy specification.

For a gummy manufacturer, the more useful approach is to characterize successful batches, understand the normal variation in a_w and validate an upper operating limit against the actual formulation and shelf-life requirements. This becomes particularly important if reformulation changes sugars, polyols, botanical extracts or other ingredients that influence water binding.

SHOULD A GUMMY ALSO TARGET 0.55-0.65 a_w ?

Not necessarily. The ASTM 0.55-0.65 a_w specification was developed specifically for dry cannabis flower, not edibles. ASTM’s own sample-preparation guidance explicitly separates flower from edibles, oils, tinctures and beverages because those matrices present different analytical challenges. [6]

Published gummy research also demonstrates why there cannot be one universal number. Formulation ingredients and their interactions can significantly change water activity, moisture retention and texture. Research on gummy formulations has shown, for example, that changing pectin-to-gelatin ratios can change a_w together with hardness, gumminess and chewiness. Other storage studies show a_w changing over time as gummies exchange moisture with their environment and packaging. [9]

The practical objective is therefore not to achieve the lowest possible a_w. A gummy that is dried too far may become progressively hard or lose its intended chew, while excessive available water can increase stickiness and microbial risk. The correct target is a product-specific stability window where microbiological safety, texture and shelf life overlap.

CAN a_w ALSO HELP WITH THC OR CBD CHEMICAL STABILITY?

Water activity can be relevant to chemical stability because available water influences molecular mobility and many reaction mechanisms. Novasina therefore considers chemical degradation an important potential shelf-life limitation once microbial growth has been brought under control in cannabis and cannabis-containing products. [7]

For THC and CBD specifically, however, it is important not to overstate the evidence. Current cannabinoid stability research shows that degradation depends strongly on temperature, formulation matrix and cannabinoid profile, while other studies have demonstrated important effects of light and oxygen. A 2026 study comparing plant material, extracts, oil formulations and isolated THC and CBD found clearly different stability profiles depending on product type and storage temperature, with THC-rich materials particularly susceptible to degradation under ambient conditions. [10]

There is currently no universal published a_w value that guarantees THC or CBD stability in a gummy. Water activity should therefore not replace cannabinoid potency testing. Instead, it can be included as one controlled variable during stability development.

A practical study would follow a_w together with THC or CBD assay, degradation products, microbiology, texture and storage conditions. If changes in chemical stability repeatedly correlate with a particular a_w region in the specific gummy formulation, that relationship can then be used to establish a meaningful product-specific control strategy.

WHERE SHOULD a_w BE MEASURED DURING GUMMY PRODUCTION?

The most useful information is usually obtained when a_w is incorporated into development and process control rather than measured only at final release.

During formulation work, it can be used to compare alternative sweeteners, extracts, carriers, pectin or gelatin systems and other ingredients. During production development, measurements after depositing, drying and conditioning can help identify when the gummy reaches a stable endpoint. Once the process is validated, measurement before packaging provides a practical check that normal production remains inside the established range.

Stability testing should then follow a_w over time. If a gummy leaves production at the correct value but gradually gains water during storage, packaging or environmental exposure may become the limiting factor. If it progressively loses water and becomes hard, the same data can point in the opposite direction.

Published gummy studies confirm that a_w changes with formulation and during storage, reinforcing the value of monitoring it as a process and shelf-life parameter rather than as a single isolated measurement. [9]

WHY IS PACKAGING PART OF THE a_w STRATEGY?

A gummy does not stop interacting with water when it enters the package. Moisture can move between the product, package headspace and external environment until equilibrium is approached. The package slows this exchange, but its effectiveness depends on the barrier material, closure, storage climate and product itself.

If the product absorbs water, a_w may increase together with stickiness, softness or microbial risk. If it loses water, the gummy can become progressively harder. A formulation change can also change the product’s moisture-sorption behavior, which means packaging that worked well for the previous formulation should not automatically be assumed to provide identical shelf-life performance for the new one.

Novasina therefore recommends considering formulation, a_w and packaging as one connected stability system rather than treating packaging validation as a completely separate exercise. [8]

WHAT CAN a_w NOT TELL YOU?

Water activity does not determine cannabinoid concentration, prove dose uniformity, establish whether a product qualifies as hemp under federal law or replace contaminant, potency or microbiological testing. A low a_w also inhibits microbial growth but does not demonstrate that microorganisms were killed during processing.

Its value is different. a_w provides a fast and highly practical measurement of the moisture environment in which the gummy, its microorganisms and its ingredients must remain throughout shelf life. Combined with pH, microbiology, cannabinoid testing, packaging studies and stability data, it gives the manufacturer information that those measurements cannot provide individually.

WHAT SHOULD GUMMY MANUFACTURERS DO NOW?

Manufacturers that may need to reformulate because of the changing U.S. hemp framework should treat that reformulation as a stability change, not only as a cannabinoid-compliance exercise.

A practical starting point is to characterize the current successful product before changing it. Establish its normal a_w, pH, texture, cannabinoid profile and relevant shelf-life performance. Once the new formulation is available, repeat the same measurements under equivalent conditions and determine whether the moisture environment has changed.

During stability studies, trend a_w together with microbiology, texture and cannabinoid potency. If the reformulated gummy remains within the established product window and performs equivalently during storage, the manufacturer has considerably stronger evidence that the change has not introduced a new moisture-related failure mechanism. If it moves outside that range, the new formulation should be validated on its own rather than relying on the stability history of the previous product.

The changing hemp market will determine which products companies can sell and how they may need to reformulate them. Water activity cannot answer the regulatory question, but it can help answer the next one: will the reformulated product remain microbiologically, physically and chemically stable throughout its intended shelf life?

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SOURCES

[1] Congressional Research Service. Changes to the Statutory Definition of Hemp and Implications for Agricultural Policy, IF13136, updated September 28, 2026. Current Congressional Research Service summary of the new federal hemp definition, total THC basis, product exclusions, 0.4 mg per-container provision, FDA implementation status and revised effective dates

[2] Public Law 119-37, Division B, Section 781, enacted November 12, 2025. Primary statutory source establishing the amended hemp definition, including total THC and the exclusions applying to intermediate and final hemp-derived cannabinoid products.

[3] Public Law 119-103, Section 2019, enacted September 2, 2026. Primary statutory source modifying the applicability timeline of Section 781 through December 11, 2026.

[4] U.S. Food and Drug Administration. FDA Regulation of Cannabis and Cannabis-Derived Products, Including Cannabidiol (CBD). FDA’s current position on THC and CBD in conventional foods, dietary supplements and interstate commerce.

[5] California Department of Public Health. Assembly Bill 8 Frequently Asked Questions. Current example of state-level regulation differing from the emerging federal hemp framework; covers California requirements applying to industrial-hemp foods and cannabinoid ingredients from January 2026.

[6] ASTM D8197-22. Standard Specification for Maintaining Acceptable Water Activity (a_w) Range (0.55 to 0.65) for Dry Cannabis Flower Intended for Human/Animal Use. Establishes the recommended range specifically for dry cannabis flower to balance microbial control and protection against excessive drying.

[7] Novasina. Water Activity in Cannabis. Application guidance covering microbial stability, chemical degradation, physical stability, storage and the use of a_w throughout cannabis processing.

[8] Novasina. Water Activity in Functional Foods and Nutraceuticals: Improving Stability and Shelf Life. Application guidance covering gummies, texture, stickiness, hardening, ingredient stability, moisture migration and packaging.

[9] Scientific literature on gummy formulation and storage. Research demonstrates that formulation changes can alter a_w and gummy texture, and that water activity and moisture change during storage depending on composition and packaging. See, for example, Effect of gelling agents on the techno-functional, collagen bioavailability and phytochemical properties of botanic gummy jelly containing marine hydrolyzed collagen (Food Chemistry Advances, 2025) and research on gummy storage stability published in the Journal of Food Measurement and Characterization.

[10] Stability of Cannabinoids in Cannabis: Plant Material, Extracts, Oil Formulations, and Isolates (CBD and Δ9-THC) Under Different Storage Conditions, 2026. Current research demonstrating that cannabinoid stability depends strongly on temperature, cannabinoid profile and formulation matrix.