Effect of orange peel essential oil on trout feed shelf life

The waste of the orange industry accounts for about 50% to 70% of the fruit, depending on the technology adopted. Although this product obtained is characterized as waste, it contains many valuable compounds and causes great economic losses for companies. In addition to being an economic loss, companies face waste management challenges due to market saturation. The disposal of orange industry waste is becoming an important problem due to its unique characteristics, economic and environmental factors, as well as some legal restrictions. One of the most important areas of aquaculture activity is fish farming. It is known that feed and feeding expenses account for 60 to 70% of the total cost of fish farming. Therefore, feed quality and feed costs are an important issues. The fish oil and fish meal used in the production of fish feed cause the fish feed to deteriorate rapidly. In order to prevent this deterioration and other quality losses, synthetic additives are added to fish feeds. However, in recent years, legal restrictions and increased consumer awareness have increased interest in natural contributions. The aim of this study is to determine the qualitative content of essential oil, which is a natural additive isolated from orange peel, a waste product of the orange juice industry, and to determine the changes occurring in the storage process of fish feeds added with this oil. In this context, orange peels to be used for the study were obtained and essential oil was obtained from orange peels using the Clevenger apparatus working with the hydrodistillation method. The fat content was determined using gas chromatography/mass spectrometry. The resulting chromatogram was checked with the W9N11 library and the qualitative content of the fat was determined. As a result of the analysis, the volatile content of the oil obtained was determined, and it was determined that the major component of the content was D-limonene. Then, the essential oil, the content of which was determined, was added to the feed ration, the suitability of which was indicated in the literature for trout, in the proportions of ‰ 0; 0,5; 1; 3 and experimental feed groups were created. The feeds were stored under standard storage conditions for 60 days in feed sacks and periodic samples were taken during storage and nutritional, microbiological, structural, and oxidation-determining analyses were performed on the samples. At the end of the study, it was determined that orange peel essential oil had not protective effect on the total mesophilic aerobic bacteria, yeast, and molds growing in fish feeds (p>0,05). Nutrient values changed over time during storage, but this change was not significantly related to the amount of orange peel oil contained in feeds (p>0,05). Orange peel essential oil added to feeds had not effect on the structural properties of feed grains. However, it has been observed that orange peel essential oil significantly inhibits the oxidation of oil in feed (p<0,05). For this reason, it has been observed that the addition of orange peel essential oil at least ‰1 to fish feeds still allows the amount of peroxide formed as a result of oil oxidation to be at acceptable values compared to other groups at the end of the 60-day storage period.