Freshtrusion® – creating the world’s finest pet food.

Gently cooked in our Meat Kitchen.

Since the introduction of Freshtrusion®, we have hailed our gentle cooking process as the best way to ‘protect the proteins’ in our Freshly Prepared meats and fish and ensure the best digestibility and nutritional value of the kibbles for the pets that eat them.

Research has demonstrated that ‘thermal processing’ (cooking) can alter the digestibility and bioavailability of proteins in meat (outlined in Figure 1). In particular, cooking at lower temperatures can induce structural/conformational changes (e.g. ‘unfolding’) in the meat proteins, which exposes more cleavage sites that the digestive protease enzymes in the gastrointestinal tract can act on to break down the protein, leading to improved protein digestibility (Bhat et al., 2021).

In contrast, high-temperature cooking can induce extensive protein oxidation, forming different kinds of cross-links and protein aggregation, making it harder for digestive enzymes to break down the protein and therefore decreasing protein digestibility (Bhat et al., 2021).

In beef muscle cooked at 100^oC, protein oxidation increased gradually over the duration of the 45-minute cooking time; the effect of rapid, high-temperature cooking (1 minute at 270^oC, reaching a maximum core meat temperature of 170^oC) on protein oxidation was similar to cooking for 30 minutes at 100^oC (Santé-Lhoutellier et al., 2008). Protein aggregation increased dramatically after 5 minutes of cooking at 100^oC and remained at a similar level after 45 minutes, with a similar increase induced by cooking for 1 minute at 270^oC. Associated with these biochemical changes, a 42% decrease of in vitro digestion rate by pepsin (a protease enzyme from the stomach responsible for the first stage of protein digestion) was seen after only 5 minutes of cooking at 100^oC and a 58% decrease was seen at 45 minutes. Cooking for 1 minute at 270^oC induced the same decrease in pepsin activity as 30 minutes of cooking at 100^oC. These decreases in pepsin digestibility rate were found to be significantly correlated with increased protein oxidation and protein aggregation. (Santé-Lhoutellier et al., 2008).

Greater results

The results showed a more rapid increase in plasma amino acid levels after eating meat cooked at 75ºC compared to 95ºC (and meat cooked at 60ºC was in between), suggesting an increased speed of digestion when the cooking temperature was increased from 60ºC to 75ºC and a decrease in the speed of digestion when the temperature was increased from 75ºC to 95ºC (Bax et al., 2013).

These results are in line with the in vitro effects described above, suggesting that cooking the meat at 75ºC resulted in the ‘unfolding’ of the protein structure, making it easier for the enzymes in the digestive tract of the minipigs to digest the protein and absorb the amino acids whereas increasing cooking temperature leads to protein oxidation and aggregation making it harder for the protein to be broken down by digestive enzymes.

Highly Nutritious Kibbles

After cooking in the Meat Kitchen, the freshly prepared meat/fish is combined with the dry ingredients in the recipe and extruded to create dry dog (and cat) foods. It has been shown that dry dog foods made with fresh meat or fish materials as the only animal protein source (diets made with either beef loin, pork loin, chicken breast, salmon fillet or pollock fillet) resulted in very high protein digestibility values (Faber et al., 2010). Average protein digestibility values from adult dogs fed each diet were 89.7% (beef), 90.5% (pork), 88.9% (chicken), 90.5% (pollock) and 89.2% (salmon).

In another study, where dry diets made with fresh meat or rendered meat meal were compared, it was found that the fresh poultry diet had significantly higher ileal protein digestibility (83%) than the poultry meal diet (74%) when fed to adult dogs (Murray et al., 1998). In the same study, a similarly high ileal protein digestibility was reported for a fresh beef diet (80.4%), and a similar result was seen for kibbles made with a rendered beef meal (79.9%), indicating the digestibility of different meat meals can be variable. In another study, the protein digestibility of a poultry meal-based dry dog food was 80.3% (Tjernsbekk et al., 2017). When a proportion of the poultry meal was partially replaced with raw chicken meat the protein digestibility of the diet was 81.3% (Tjernsbekk et al., 2017).

In contrast, high-temperature cooking can induce extensive protein oxidation, forming different kinds of cross-links and protein aggregation, making it harder for digestive enzymes to break down the protein and therefore decreasing protein digestibility (Bhat et al., 2021).

A study was performed on a GA diet containing 55% Freshly Prepared poultry and fish ingredients plus 23% chicken meal (Brierley, 2019). Pepsin digestibility of the kibbles tested in vitro was 91% and the in vivo protein digestibility following a feeding trial in 10 dogs was 80.3% (N.B. it is not unusual for in vivo protein digestibility to be lower than in vitro values, Biagi et al., 2016).