Assessment of chemical composition and bioactive compounds in the peel, pulp and whole Egyptian eggplant flour

Abstract EN

Eggplant (Solanum melongena L.

) is one of the most popular common major vegetable crops worldwide.

Eggplant flour prepared by to freeze drying is a highly desirable food ingredient.

However, there are few data on the chemical composition of the parts (pulp and peel) of Egyptian eggplant flour.

Therefore, the objective of this study was to determine the proximate chemical composition, minerals, amino acids and bioactive compounds in pulp, peel and whole Egyptian eggplant flour.

The results of this investigation indicated that the peel of eggplant contained the highest amount of total dietary fiber (43.31% ), insoluble dietary fiber (29.31% ) and ash (6.20% ) and lowest energy value (172.96 Kcal/100g dw) compared to the pulp and the whole eggplant flour.

Eggplant peel contained highest amount of potassium, magnesium, iron and zinc compared with the pulp and the whole eggplant flour.

Egyptian eggplant parts are rich source of amino acids (essential and non- essential).

eighteen amino acids compounds were determined in eggplant parts with different concentrations.

The results showed that the peel contained higher levels of total phenolic contents, total flavonoids and total anthocyanins than the pulp and the whole eggplant flour.

Using HPLC, eighteen phenolic compounds were identified in the peel showed.

5- Caffeoylquinic acid (chlorogenic acid) was a major phenolic acid in eggplant peel representing 89.9% of total phenolic compounds.

The highest levels flavonoids compounds in peel were quercetin-3-diglucoside, Myricetin-3-galactosid and Quercetin-3-rhamnoside.

The major four eggplant skin anthocyanins characterized by HPLC-MS were delphinidin 3-rutinoside-5-galactoside (4.2% ), delphinidin 3- rutinoside-5-glucoside (8.1% ), delphinidin-3-glucoside (3.7% ) and delphinidin-3- rutinoside (84% ).

Moreover, ascorbic acid and β-carotene contents were in higher amount in eggplant peel (17 mg per 100 g and 28 mg per 100 g, respectively) than in eggplant pulp.

Eggplant flour, especially peels, could therefore be used as a good source of dietary fiber, minerals and phytonutrients and may be used as supplements in diets low in such compounds.