Evaluation of Lychee Fruits and Effect of Osmotic Treatments on Flesh Quality

The lychee (Litchi chinensis Sonn.) fruits (a species of the Sapindaceae family) is of Chinese origin and is perfectly adapted to Egyptian climatic conditions. This study included the evaluation of fresh lychee flesh, seeds and pericarps, also fresh lychee flesh treated with sugar solution (sucrose 20 °Brix) in refrigerator (4±1°C) during storage for 12 months, also fresh lychee flesh treated with sucrose 40 °Brix (as an osmotic agent) was dehydrated in air oven drier (60°C) and oven drier under vacuum (50°C) at ambient temperature (25±2°C) during storage for 12 months. The obtained results showed that, fresh flesh lychee was higher in weight percentage (73.22%) than lychee seeds and pericarps (17.58 and 9.20%, respectively) of the total weight of fruits. There were also, no significant variance in crude oil content between fresh flesh lychee and flesh lychee in sugar solution (0.68 and 0.63%), respectively. While, lychee seeds were possessing high content of crude oil (3.72%) followed by lychee flesh dried under vacuum and oven dry (3.62 and 3.53%, respectively) after dipping in sugar agent, then crude oil in pericarps were the lowest content of crude oil (2.98%). While, protein and crude fiber contents were higher in pericarps (9.25 and 28.34%) respectively, than seeds (8.73 and 21.42%), also the content of protein and crude fiber were nearly in dried lychee under two treatments of dehydration (6.94, 7.02 and 6.84 and 6.88%), respectively. Furthermore, dried flesh lychee in oven or under vacuum gave high calories (374.45 and 375.22 kcal./100g), respectively, followed by lychee seeds then pericarps (317.78 and 287.26 kcal./100g). Results, also indicated that, lychee seeds were having the highest contents of  6 and  9 (2226.65 and 1144.56 mg/100g, on dry weight basis), respectively. While, fresh lychee flesh treated with osmotic solution was decrease in  9, 6 and 3 contents (79.25, 95.87 and 29.61 mg/100g, on fresh weight basis, respectively) compared to fresh lychee flesh without any treatment (98.94, 117.16 and 39.92 mg/100g, on fresh weight basis), respectively. Also, lychee flesh dried under vacuum was higher contents in  6 and  3 (924.84 and 393.48 mg/100g, on dry weight basis, respectively) than dried by oven dryer, while the same treatment had highest content in  3 than other treatment and other parts of lychee fruit (seeds and pericarps). The results also indicated that, lychee seeds had highest content of total polyphenols, total flavonoids, total carotenoids, L-ascorbic acid and anthocyanins followed by lychee pericarps then fresh lychee flesh except vitamin C, fresh lychee flesh had higher contents then pericarps. These results reflected to antioxidant activity, whereas, seeds had higher antioxidant activity (87.00%) than fresh lychee flesh and pericarps (81.00 and 78.00%), respectively. The results showed that, the total soluble solids, pH and acidity were ranged from 16.50, 4.42 and 0.38 to 15.95, 4.36 and 0.45, respectively in fresh osmotic lychee flesh during refrigeration storage. The contents of total polyphenols, total flavonoids and total carotenoids had not significant changes during storage for 12 months. While, vitamin C content was decrease 1.46% in after storage 12 months, but this decrement is not statistical significance. The results total polyphenols, total flavonoids, total carotenoids and anthocyanins contents in oven dried (60°C) on osmotic lychee flesh during storage for 12 months at room temperature (25±2°C) had no significantly decrease changes till 8 months. Also, vitamin C contents in osmotic lychee flesh affected by oven dry treatment till 6 months, in addition, vitamin C contents was decreased significant till the end of experiment (7.10%). While, total polyphenols, carotenoids, anthocyanins contents had no significant decrease till 10 months in dried osmotic lychee flesh at 50°C under vacuum (Osmovac) treatment. But, it’s observed the content of vitamin C was gradually significant decreased (from 360.38 to 350.00 mg/100g on dry weight), the percentage of decrement was 2.88% at the end of storage in osmovac treatment. Advances in Food Science and Engineering, Vol. 3, No. 3, September 2019 https://dx.doi. org/10.22606/afse.2019. 33002 37 Copyright © 2019 Isaac Scientific Publishing AFSE The results confirmed that, the fresh lychee flesh treated with osmatic agent and dried lychee flesh at 50°C under vacuum (Osmovac) were the most suitable treatments for storing and keeping the antioxidant contents, especially vitamin C. Also, osmovac treatments can retain their high quality of lychee flesh for 1 year at room temperature compared to osmotic oven dried at 60°C flesh lychee fruits (8 months). While, seeds and pericarps were rich in bioactive components as omega fatty acids, anthocyanins and others, may use in food and pharmaceutical products for their value for sustainable development in future studies.