3. Results
3.1. Pelleting process parameters
Conditioner temperatures reached the target temperatures of 65 and 90◦C (Table 2), while product temperatures at thedie exit were approximately 10 degrees higher. Electric consumption as well as the capacity of the pellet press increasedwhen temperature was raised from 60 to 90◦C.
3.2. Unprocessed ingredient mix
The unprocessed ingredient mix consisted of 253.2 g/kg protein, of which approximately 30 g/kg originates fromhydrolyzed poultry meal (Table 1). In addition, the unprocessed ingredient mix contained 326.8 g/kg starch, of which32.6 g/kg was from the reducing sugars.
3.3. Effect of steam pelleting on chemical parameters
The effect of the steam pelleting processes (unprocessed ingredient mix vs. pelleted food) on chemical parameters isshown in Table 3. Neither absorbance at 280 nor at 420 nm was affected by steam pelleting, with values for 420 nm closeto 1. For the color values, lightness L* and a* were not affected by steam pelleting. The b* value significantly decreased aftersteam pelleting from 17.6 to 16.4, as well as the values for C* from 172.4 to 151.6 and E from 1555.4 to 1488.3. The steampelleting processes applied to the ingredient mix had no effect on TL and OMIU-RL contents and RL/TL ratio. Contrary to thelysine results, FL content significantly increased from 366.2 to 538.8 mg/kg DM, CML content from 12.6 to 14.8 mg/kg DMand LAL content from 5.7 to 7.7 mg/kg DM after the steam pelleting was applied to the ingredient mix. HMF content was notaffected by steam pelleting.