Thermostability of OptiPhos® Plus

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Article | 23.11.2020

Thermostability is an important characteristic of a phytase. Their ability to withstand the rigors of the pelleting process can have a big impact on efficacy and animal performance. 

OptiPhos® Plus is available in two dry forms for use in feed: 

  • OptiPhos® Plus G (granular) - heat stable up to 85oC
  • OptiPhos® Plus CT (coated) - heat stable up to 95oC

A total of 14 pelleting trials in Europe (in five different locations) and six in the USA (in five different locations) have been conducted since 2017 using both product forms. In most of these trials, competitor products were also included to compare the performance of OptiPhos® Plus to commercial standards. 

The most frequently used competitor products were a Buttiauxella phytase and an E. coli phytase expressed in Trichoderma reesii with a claim of being intrinsically heat stable. The large number of trial locations provided a variety of pelleting installations, mimicking real situations in the field. 

The pelleting parameters of these trials ranged from: 

  • Conditioning time: 15 to 75 seconds
  • Pellet diameter: 3 to 4.5 mm
  • Pelleting temperature: 75oC to 95oC

Thermostability means a recovery of at least 80%. Recoveries were determined in two ways: 

Recovery considering the real analysed dose - real recovery

Recovery (%) = (phytase in supplemented pellet - phytase in blank pellet) / (phytase in supplemented mash - phytase in blank mash) x 100%

Recovery considering the theoretical dose - recover of label claim

Some competitors put a large amount of phytase overage in their product to meet the required activity level in the final pelleted feed. For instance, a 1,000 FTU/kg pelleted feed can be achieved even when 50% of the initial phytase activity is lost when the phytase product claims 10,000 FTU/g but in fact actually contains 20,000 FTU/g.

All data from the pelleting studies are plotted in Figures 1 and 2, including a best fitting curve.

Figure 1. Average recovery of OptiPhos® Plus CT and G versus competitors as determined by real analysed value
Figure 2. Average recovery of OptiPhos® Plus CT and G versus competitors as determined by label claim considering the excess (overage) of phytase in the product

It can be concluded that: 

  • OptiPhos® Plus G and OptiPhos® Plus CT are heat stable up to 85oC. 
  • OptiPhos® Plus CT has a higher thermostability of up to 95oC without significant losses.
  • OptiPhos® Plus G and CT are much more heat stable than the Buttiauxella phytase and the claimed intrinsically heat stable E. coli phytase expressed in Trichoderma reesii
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