# Enhancing the Integration of Protein-Rich Oat Waste Material into Meat Formulations
## 4 Discussion
### Assessing the Possibility of Using OPH as a Meat Additive  
Water holding capacity (WHC) is one of the most important properties of meat and meat products. It is described as the ability to hold the water (its own or added) within the muscle fibres or in an emulsion. Therefore, increased WHC is a desirable property worth improving [41]. All the additives used as fillers or extenders in the meat industry must meet specific requirements, including exhibiting a neutral colour, taste, and smell; a high water holding capacity; or emulsifying properties. If it is to be used for ham injection, the additive must additionally be soluble. For this reason, OPH was tested for its binding- and yield-promoting abilities. The increased pH of meat leads to an increase in water holding capacity in the formulations, which is proportional to the amount of added OPH. These results are in agreement with those obtained from previous studies in which a higher pH enhanced water holding capacity and firmness [41]. However, in sausages prepared with a plasma hydrolysate, the opposite effect could be observed. The pH of the batters decreased, along with the plasma concentrations, and changes in yields were not noted [42]. Another reason for the increase in WHC could simply be an addition of proteins, which usually promotes water retention within the samples; however, the opposite effect may occur, as it did in our previous study [43]. In the trial, an increased protein content (achieved by hemy protein implementation) did not increase WHC because of the edestin properties. The cooking yields for the Control, 1H, 2H, and 3H were 90.6%, 91.9%, 92.7%, and 93.7%, respectively. A close analysis of the effect of OPH in terms of water and fat binding revealed that water binding increased with OPH concentration, but apparently, fat binding was not affected. All the samples exhibited a comparable fat content, regardless of the OPH concentration. By comparing the actual change between the raw and cooked samples, calculated as a percentage of fat in the dry matter, it can be observed that more fat was retained in the Control. Similar results were achieved in our previous study, in which we used a soybean protein hydrolysate as a meat additive [19]. The analysis of cooking loss showed that samples with soybean protein hydrolysates retained more water and less fat compared to the control samples. This may have resulted from the fact that along with the protein hydrolysate, additional proteins were introduced, and the amount of fat was proportionally lower. The colour differences were noted between samples. According to [PERSON] et al. [44], differences in \(\Delta\)E values below 2.15 are not discernible. Therefore, in our case, only 3% of the OPH concentration would be effective. However, we were already able to see the difference at 2%. [PERSON] et al. [45] noted 30% of correctly perceived differences between products at \(\Delta\)E = 1, which proves that \(\Delta\)E values close to 2.0 could definitely be distinguished by consumers. One of the most important results is that the a* parameter was stable during the storage period in 2H and 3H, in contrast to 1H and the Controls, in which the a* parameter had already decreased within the first 7 days of storage. On the other hand, redness, calculated as the a*/b* ratio, also dropped in the 3H sample during storage, as well as in all the other samples, but it was much more significant in 3H. These results indicate that OPH could be used in meat processing as a substance for supporting the pink colour formation in the \"nitrite free\" products or in those with a lower nitrite content. This quality seems to be especially important, considering the latest changes in European Union Regulation 1333/2033 [46], in which a significant decrease (i.e., 80 vs. 150 ppm of nitrite in a large group of cured products) will be required by the October 2025. These observations led us to a further investigation regarding the cause of such a phenomenon.