The product designated EHSP-10G is a granular 6-phytase preparation with a declared minimum activity of 10,000 FTU/g determined by ISO 30024:2009. The enzyme is produced by submerged fermentation of a fungal donor strain and is formulated as a coated microgranule for dry addition to compound feed prior to steam conditioning and pelleting. The catalytic function is the sequential hydrolysis of myo-inositol hexakisphosphate to lower inositol phosphates and inorganic phosphate, with the first cleavage occurring preferentially at the C6 position. The preparation is intended for monogastric feed applications in which intrinsic phytate-bound phosphorus is converted to absorbable inorganic phosphorus. Typical in-feed targets range from 250 FTU/kg in layer diets to 1,000 FTU/kg in piglet creep feeds, with the final dose dependent on dietary calcium-to-phosphorus ratio, phytate substrate load, and pellet conditioning severity. The granular formulation exhibits a bulk density of approximately 0.65 kg/L and a particle size distribution in which not less than 90% by mass is retained between 250 µm and 850 µm sieves, allowing homogeneous dispersion in premixes and compound feeds during low-inclusion dry blending.

The heat-stable designation refers to retention of catalytic activity after hydrothermal treatment rather than intrinsic thermophilicity of the free enzyme. The formulated granule contains an inorganic salt buffer and a hydrophobic coating that delays moisture ingress during the conditioner dwell time. Denaturation onset in differential scanning calorimetry is therefore not equivalent to the midpoint of unfolding of the uncoated enzyme; the apparent inactivation boundary is shifted by the coating and by the rapid evaporative cooling after the die plate.

What Are the Practical Limits of Hydrothermal Pellet Survival?

Survival data are normally generated on production-scale systems rather than laboratory ovens, because dry heat and steam conditioning act through different inactivation kinetics. A split-plot feed mill evaluation using a horizontal paddle conditioner with 45 s barrel retention, a 4.0 mm die by 60 mm effective thickness, and a counterflow pellet cooler was conducted at conditioner outlet temperatures of 80°C, 85°C, 90°C, and 95°C. Feed was a maize–soybean meal broiler grower with 12.0% added moisture at the mixer and 2.2 bar steam pressure. Post-pellet activity was extracted from freeze-milled pellet samples passing a 0.5 mm sieve and assayed by ISO 30024:2009.

Steam moisture, not temperature alone, is the dominant inactivation vector. Dry heating of the same granule in a ventilated oven at 95°C for 30 min produced a residual activity above 90%, confirming that condensation onto the coating during conditioning is the critical event leading to enzyme release and denaturation. Conditioner meal moisture above 16.5% is therefore a process limit; above this value, survival falls by approximately 8–12 percentage points for each additional 1.0% moisture at constant temperature. Retention time variability of ±5 s in a paddle conditioner produced a 7 percentage point range in post-pellet activity across production shifts. Inactivation during conditioning follows apparent first-order kinetics over the first 60 s of wet heat exposure. The calculated inactivation rate constant for EHSP-10G at 90°C and 16.0% meal moisture is approximately 0.005 s⁻¹; for an uncoated 6-phytase control under identical conditions, the corresponding value is approximately 0.021 s⁻¹. The apparent activation energy of inactivation in the coated granule is 145 kJ/mol, compared with 112 kJ/mol for the uncoated enzyme. These values are derived from internal retention samples and are single-trial representative ranges, not guaranteed specifications.

Batch release for EHSP-10G follows the analytical profile below. The product is certified for dry addition to complete feed and premixtures and is shipped in 25 kg multi-wall paper sacks with a polyethylene liner. Storage stability data indicate a loss of not more than 10% of declared activity after 12 months at 25°C in unopened packaging. The coated microgranule is produced by concentration of the fermentation broth by ultrafiltration, followed by spray granulation onto a salt-starch core and fluidized-bed coating with a hydrophobic matrix. Coating integrity is assessed by a dissolution test in 0.08 mol/L acetate buffer at 40°C; after 10 min, less than 15% of declared activity is released.

The Stauber-Heubach dust value is assessed on the undiluted granule; in a premixture at 10% enzyme concentration, the dust fraction is below the detection limit of the same method.

When Dry Addition Preceding Pelleting Replaces Post-Pellet Liquid Spraying

In feed mills operating with conditioner outlet temperatures of 85–90°C, post-pellet liquid phytase application has historically been used to avoid thermal inactivation. With EHSP-10G, dry addition at the mixer is feasible because post-pellet survival at 90°C remains above 80% under the process conditions specified above. This removes the need for post-pellet metering pumps, spray nozzles, and liquid enzyme storage lines on twin-shaft paddle mixers with batch capacities between 250 kg and 2,000 kg or continuous mixers processing 20 t/h.

Mixer addition should be made after the dry minerals and before the addition of liquid fat. A dry mixing time of 120 s at a mixer fill factor of 60% gives a coefficient of variation below 10% for enzyme activity in ten grab samples. If the mixer fill factor exceeds 80%, the required mixing time is extended to 180 s because axial dispersion is reduced in overfilled chambers. In a twin-shaft mixer with 2,000 kg batch size, adding 100 g of EHSP-10G per batch achieves 500 FTU/kg before pelleting. For smaller batch mixers of 250 kg, the weight addition is 12.5 g per batch, which requires a micro-ingredient scale with accuracy of ±0.1 g.

Target in-feed activity after pelleting should be confirmed by extraction and assay. In broiler grower diets with 0.85% calcium and 0.38% available phosphorus, a target of 500 FTU/kg is typical. The pre-pellet dose is calculated by dividing the target by the expected thermal survival fraction at the highest conditioner temperature. At 90°C and 30 s retention, a pre-pellet dose of 600 FTU/kg provides a post-pellet measured activity of approximately 504 FTU/kg, using the 84% survival fraction. At 95°C, the pre-pellet dose is raised to 700 FTU/kg to maintain approximately 497 FTU/kg after pelleting. Overdosing above 2,000 FTU/kg does not linearly release additional phosphorus; the phytate hydrolysis curve approaches saturation because substrate accessibility and gastric retention time become limiting. Matrix values for phosphorus replacement should be assigned only after in vivo ileal digestibility or performance validation. Published comparative literature on 6-phytases indicates that 500 FTU/kg can replace 0.10–0.12% available phosphorus depending on calcium and phytate content, but batch-level feed formulation changes require confirmation under the specific dietary context.

Gastric pH Profile and Pepsin Stability Compared with 3-Phytase Systems

EHSP-10G exhibits a pH activity profile that differs from most 3-phytase preparations from Aspergillus niger. The 6-phytase retains at least 70% of maximum activity between pH 2.5 and pH 5.5, whereas a conventional 3-phytase reference shows a sharp decline below pH 3.0. After incubation for 120 min in simulated gastric fluid containing 2,000 U/mL porcine pepsin at pH 2.0 and 37°C, the 6-phytase retains 65–75% of initial activity, compared with 25–40% for a typical uncoated 3-phytase. The broader pH window is relevant in the broiler proventriculus and gizzard, where luminal pH ranges from 2.8 to 4.5 before neutralization in the small intestine. The difference arises from the active-site architecture of 6-phytase and from glycosylation extent, not from a simple shift in isoelectric point.

In comparison with a coated 3-phytase product, EHSP-10G also shows a lower early release of active enzyme in the mash stage. This reduces activity loss during preconditioning but can delay initial hydrolysis in the crop. In poultry assays, the delay is not biologically significant at standard dosages because proventricular residence time exceeds 45 min. Published data for this specific formulation in non-standard species is limited; for duck and turkey, additional validation is required.

EHSP-10G should not be incorporated into acidified premixes containing free organic acids at concentrations above 10% before dilution into final feed. Premix moisture above 13.5% requires drying before enzyme addition to prevent premature coating disintegration. The granule coating is incompatible with long-chain aldehyde-based sanitizers used in liquid post-pellet application lines; if post-pellet liquid phytase or other enzymes are used simultaneously, separate flushing with demineralized water is required. The bagged product should be stored at or below 25°C and protected from moisture. Opened sacks should be consumed within 30 days to prevent activity loss above the specified 10% storage limit. The product is not recommended as the sole phytase source in extruded aquafeed processed above 105°C barrel temperature and 22% moisture because the combined hydrothermal residence time exceeds the coating tolerance; published data for this specific configuration is limited. Batch-to-batch variation in post-pellet survival is below 5 percentage points when assayed by ISO 30024:2009 on cooled pellet samples, based on internal retention data.

One production-scale failure mode observed with dry phytase addition is incomplete enzyme extraction from pellets. If pellets are not freeze-milled below 0.5 mm before assay, apparent activity can understate actual survival by 15–20%. This analytical artifact is excluded by applying the full extraction protocol of ISO 30024:2009 to frozen, ground pellet samples. In compound feed containing choline chloride as a separate granule, physical segregation can occur if the particle size difference exceeds 300 µm; segregation testing using a six-section mixer sampling probe is recommended. The product is not classified as hazardous under REACH or GHS in the as-supplied solid form, but respiratory protection for dust exposure is required when handling the undiluted granule at levels above 10 mg/m³ inhalable dust. The granule is stable to 60°C dry storage for 4 weeks without loss, but pallet storage in direct sunlight should be avoided because sack surface temperatures can exceed 50°C even at ambient air temperatures below 30°C.