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Stability of commercial phytase products stored under different environmental conditions
A 300-d study evaluated the stability of 4 phytase products stored under varied environmental conditions. The 4 products were: 1) Quantum Blue 5G (AB Vista, Marlborough, United Kingdom); 2) Ronozyme HiPhos GT 2700 (DSM Nutritional Products, Parsippany, NJ); 3) Axtra Phy TPT (Dupont, Wilmington, DE); and 4) Microtech 5000 Plus (Guangdong VTR Bio-Tech Co., Ltd., Guangdong, China). Products were stored as pure forms at -20, 4, 22, or 35˚C (75% humidity), or in a vitamin or vitamin trace mineral (VTM) premix at 22 and 35˚C (75% humidity). Samples were stored in paper bags and sampled on d 30, 60, 90, 120, 210, and 300. Stability was determined as amount of residual phytase activity (% of initial). For pure forms, all interactive and main effects of product, time, and temperature were significant (P<0.05). From d 30 to 300, products had similar reductions in phytase activity at the 3 highest temperatures; however, Quantum Blue 5G, Ronozyme HiPhos GT 2700, and Axtra Phy TPT had reduced (P<0.05) phytase activity compared to Microtech 5000 Plus at -20˚C. As storage time increased, residual phytase activity was reduced (P<0.05) regardless of product and storage temperature. Also, when product was stored at 4 and 22˚C, phytase activity was improved compared to -20 and 35˚C. For vitamin and VTM premixes, a time×temperature×product interaction (P<0.05) was observed as a result of, Axtra Phy TPT and Microtech 5000 Plus having reduced residual phytase activity (P<0.05) compared to the other 2 products when stored at 22˚C, while activity of Axtra Phy TPT was reduced (P<0.05) even further than the other 3 products when stored at 35˚C regardless of form. From d 30 to 300, Axtra Phy TPT and Microtech 5000 Plus had the lowest (P<0.05) residual phytase activity compared to the other 2 products. The VTM had decreased (P<0.05) residual phytase activity compared to the pure product and vitamin premixes. In conclusion, phytase stored for longer than 90-120 d at 35˚C or -20˚C in pure form, or when stored as a VTM premix had reduced residual phytase activity.
Residual phytase activity, %1 |
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Sampling, d |
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Probability, P< |
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Item |
30 |
60 |
90 |
120 |
210 |
300 |
SEM |
Storage form main effect |
|
Pure product |
95.1 |
96.8 |
97.2 |
93.5 |
90.7 |
82.0 |
5.30 |
0.001 |
|
Vitamin premix |
106.9 |
100.8 |
100.4 |
96.6 |
88.3 |
77.9 |
|
|
|
VTM |
95.5 |
58.5 |
77.2 |
78.0 |
54.6 |
39.0 |
|
|
|
1 Stability was measured as the analyzed phytase concentration divided by d 0 phytase concentration. |
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Keywords: phytase, storage, stability