3.2.4. Frozen Storage of Grated Peels (GP)

Freezing is a commonly used food preservation method, as it slows down the chemical reactions that affect food quality, and retain flavor, texture, and nutritional quality of the final products better than other methods [31]. Orange peels can be stored as frozen forms to be evaluated as a by-product, to prolong its shelf life without any deterioration in its physicochemical structure, and can be used as an ingredient in pastry products.

In the scope of the study, pesticide residues in GP were significantly higher (*p* < 0.05) than the residue levels of the control orange samples (TC) (Table 1). Comparing the residue level of the frozen grated peels with the fresh peels (P), it was observed that there was a significant difference (*p* < 0.05), except for in abamectin. It can be related to the difference between the structure of the GP and P samples. GP was obtained by grating the top layer of the peel which did not contain any trace of the mesocarb section. As a result of a three-month storage periods, it was observed that pesticide residues in GP decreased significantly (*p* < 0.05). Therefore, it was concluded that the storage period affected the residue concentrations. Processing factors changed between 1.91 and 6.07, 1.780 and 5.33, 1.11 and 4.80, after the first, second, and third month of the frozen storage periods, respectively. Similarly, Ögüt et al. [37] reported that diazinon, parathion-methyl, captan, methidathion, cypermethrin, and deltamethrin residues in frozen cherries decreased during storage. The other studies reported in the literature supported these findings [37,38]
