# Application of Natural Antioxidants from Fruits Waste for Improving Egg Quality Characteristics
## 4 Fruit Waste Bioactive Compounds and Antioxidant Potential
The waste contains a similar nutritional content in terms of protein (11.44%), with a higher fat content (8.92%) and lower fiber content (23.26%), while the total polyphenols (90.72 mg/g GAE), antioxidant capacity (118.5 mM Trolox), and flavonoids' content (120.01 mg eq. rutin/g) exceed those of rosehip's [37]. Both by-products are rich in vitamins, carotenoids, flavonoids, and essential fatty acids, making them highly valuable for poultry nutrition [52]. Pomegranate peels are another rich source of antioxidants. The waste from pomegranates mainly comes from the peel and seeds, which account for about 54% of the fruit [53]. Pomegranate production is significant in India, Iran, and the Mediterranean region, providing substantial amounts of peel waste, especially during juice production [54]. A different content of crude protein was reported in the seeds (6.71-8.11%) and rind (3.96-7.13%). A moderate amount of ash was reported (1.61-2.29% in seeds versus 3.71-4.97% in rind); and crude fiber content in rind (28.10-33.93%) compared with that from seeds (17.33-27.84%) was reported [27; 55]. The high content of crude fiber could be a limiting factor for poultry; it could impact the bioavailability of nutrients in the laying hens' digestive tract, where it could interfere with nutrients and reduce their absorption, if the diets are not designed accordingly [39]. However, the bioactive compounds present in waste were shown to have antioxidant, anti-inflammatory, and antimicrobial properties [56]. The production of some tropical fruits, such as mango, generates peel and seed waste that accounts for around 35-45% of the fruit's weight. India, which is the largest mango producer globally, along with countries in Southeast Asia, leads in generating this waste [54]. The waste of mango represents 35-60% of the fruit, mainly from the peel and seed, with an estimated yearly waste of 14.7 to 25.2 million tons per year, as reported by [54]. Mango peels are rich in polyphenols, carotenoids, and vitamin C, while the seeds (kernels) contain significant levels of antioxidants like gallotannins and gallic acid. The nutritional composition of the peel is 11.67% protein, 42.24% fat, 6.32% fiber, 32.31% carbohydrates, and 1.65% ash, with bioactive compounds like polyphenols and carotenoids [57]. Bananas are one of the most consumed fruits, with global production exceeding 115 million tons annually [58]. The peel represents approximately 30-40% of the fruit's mass. Countries such as India and Ecuador, which are the top banana producers, generate a significant amount of peel waste, as reported by [PERSON] et al. [59]. Banana peels, another widely discarded fruit waste, contain numerous bioactive compounds, including polyphenols (60.39 to 115.70 mg/g GAE), rutin (973.08 mg/100 g), tannins (1130 mg TAE/100 g), flavonoids (196 mg/g QE), dopamine, and carotenoids [60], as presented in Table 1. It was reported that banana peel waste contains important concentrations of minerals like calcium (173.33 to 178.33 mg/100 g), potassium (75.00 to 76.67 mg/100 g), magnesium (38.33 to 43.33 mg/100 g), and sodium (248.33 to 250 mg/100 g) [61]. From the nutritional profile, the carbohydrates are abundant (63.82%), followed by fiber (12.67%), ash (9.56%), protein (3.23%), and fat (0.89%) [62]. Although less commonly used in poultry nutrition compared to other fruit wastes, banana peels offer promising antioxidant potential. Berries are other interesting food wastes that contribute to waste mainly through damaged or overripe fruits, accounting for around 10-20% of their production. The United States, Poland, and Spain are major berry producers and contributors to this waste production [42]. These by-products are exceptionally rich in anthocyanins, flavonoids, and other polyphenic compounds, which are known for their strong antioxidant effects [63; 64].