# Physicochemical Properties of Apple Purees and Peel Extract for Potential Use in Pastry Products
## 4 Conclusions  
The results of this research confirmed the variation over time in the physicochemical properties of apple puree and apple peel extract. Thus, the total content of soluble solids, the ash content, the pH and the titratable acidity increased during the storage period. Instead, the total content of polyphenols and the antioxidant activity of the samples decreased during the storage period, with the exception of the polyphenol content of the peel extract. This fact leads to the confirmation of the existence of the link between the total content of polyphenols and the antioxidant activity, polyphenols being a factor influencing the antioxidant activity. Also, the results confirmed the variation in the physicochemical properties, polyphenol content and antioxidant activity depending on the anatomical part of the apple from which the samples were obtained. In addition, the results demonstrated an increase in polyphenol content and antioxidant activity in the case of thermally treated samples.  
Knowing the physicochemical properties of apple purees allows the appropriate choice of technological parameters for obtaining pastry products in which they will totally or partially replace sugar. The three products obtained from apples can be used separately or in combination depending on the textural and organoleptic characteristics of the finished products. The microbiological analyses carried out allow for establishing the time interval within which the three products can be used safely. The use of puree and apple peel extract to replace sucrose in pastry and bakery products represents an alternative in obtaining healthier products both by reducing the energy value of the products obtained and by increasing the nutritional value due to the high content of polyphenols and mineral elements.  
The proportions in which sugar can be replaced with apple puree will be followed, to what extent the liquid phase can be partially or totally formed from the apple peel extract, technological parameters (temperature and baking time), so that the resulting product is comparable to the samples of control in terms of texture, color, aroma and taste, and more valuable from a nutritional point of view.  
[PERSON] and A.S. contributed equally to the collection of data and preparation of the paper. All authors have read and agreed to the published version of the manuscript.  
This research received no external funding.  
Not applicable.  
The data presented in this study are available upon request from the corresponding author.  
This work was funded by the Ministry of Research, Innovation and Digitalization within Program 1--Development of national research and development system, Subprogram 1.2--Institutional Performance--RDI excellence funding projects, under contract no. 10 PFE/2021.  
The authors declare no conflicts of interest.  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Sample** & **Na** & **Mg** & **Ca** & **K** & **Cu** & **Mn** & **Zn** & **Fe** \\ \hline Raw puree & 0.18 \(\pm\) 0.00 b  & 63.00 \(\pm\) 0.8 b  & 62.67 \(\pm\) 1.62 b  & 48.00 \(\pm\) 2.12 b  & 0.19 \(\pm\) 0.00 ab  & 0.11 \(\pm\) 0.00 ab  & 0.06 \(\pm\) 0.00 a  & 0.03 \(\pm\) 0.00 a  \\ Cooked & 0.61 \(\pm\) 0.00 b  & 0.17 \(\pm\) 0.00 c  & 48.67 \(\pm\) 0.40 c  & 41.67 \(\pm\) 0.41 c  & 0.02 \(\pm\) 0.00 b  & 0.07 \(\pm\) 0.00 b  & 0.02 \(\pm\) 0.00 b  & 0.01 \(\pm\) 0.00 b  \\ Apple peel extract & 563.33 \(\pm\) 20.5 a  & 273.33 \(\pm\) 9.4 a  & 72.67 \(\pm\) 0.16 a  & 64.33 \(\pm\) 1.6 a  & 0.42 \(\pm\) 0.11 a  & 0.15 \(\pm\) 0.00 a  & 0.07 \(\pm\) 0.00 a  & 0.03 \(\pm\) 0.00 a  \\ \hline \hline \end{tabular} Values followed by different superscript letters (a, b, c) are statistically different at 95% confidence level.  
\end{table}
Table 4: Concentration values of mineral elements in apples puree and apple peel extract samples (mg/kg).