Bioactive and Antimicrobial Properties of Eggplant (Solanum melongena L.) under Microwave Cooking

Abstract

Fruits and vegetables constitute a considerable amount of antioxidants and among them eggplant is a rich source of polyphenol compounds. This study investigated the bioactive and antimicrobial properties of eggplant under different degree of microwave cooking. The eggplant was cooked for 7 min (light cooked), 10 min (medium cooked), and 15 min (high cooked). The highest total polyphenol content was observed in the light cooked eggplant sample (27.35 mg gallic acid equivalent (GAE)/g dry weight (DW)) followed by high cooked sample (26.10 mg GAE/g DW), while the lowest total polyphenol content (2.79 mg GAE/g DW) was obtained for the uncooked (control) sample. The total polyphenol content of the samples ranged in the following order; light cooked > high cooked > medium cooked > uncooked. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging of eggplant ranged between 16.16% (control) and 47.88% (high cooked). The highest reducing power was exhibited by the light cooked (absorbance 1.708) eggplant sample followed by the high cooked (absorbance 1.597), while the lowest reducing power was shown by uncooked sample (absorbance 0.389). Moreover, antimicrobial studies showed that light cooked eggplant sample demonstrated broad-spectrum inhibition of growth in Gram-positive as well as Gram-negative bacteria and Candida albicans. Slightly lower antimicrobial potential was exhibited by medium cooked eggplant sample while no antibacterial or antifungal activity was recorded for the extract of high cooked eggplant sample. Microwave cooking might be a method to enhance the antioxidant and antimicrobial potential of eggplant.

Migration of Avocado Virgin Oil Functional Compounds during Domestic Cooking of Eggplant

“…The diversity of polyphenolic compounds present in raw eggplant is widely recognized, but in our study, only were confirmed with standards chlorogenic acid, tyrosol and p-vanillin, being chlorogenic the most abundant (37.8 mg GAE/kg f.w.). Compounds found in our study have been previously reported in raw eggplant, additionally to caffeic acid [61], ferulic, and p-coumaric acid [24,62]. Chlorogenic acid is a hydroxycinnamic acid-derivative; this family of phenolics accounts for 95.6% of the total identified phenolic compounds in eggplant [24].…”

“…In addition, deep-frying also contributed to p-coumaric acid, ferulic acid, sinapic acid, and quercetin. The phenols added were reported before in the fresh or processed eggplant without oil, as in the case of chlorogenic acid, caffeic acid, and vanillin in fresh and microwaved eggplant [61]; also as in the case of ferulic and p-coumaric acids [24,62]. The concentration of individual phenols found in the fresh vegetable phenolic profile increased with all the culinary techniques tested standing out deep-frying.…”

Oxidative and Microbial Stability of a Traditional Appetizer: Aubergine Salad

“…These antioxidants can derive from all plant-based ingredients, which are good sources of antioxidants. However, a higher contribution is expected from the eggplant fruits (the content of polyphenols in eggplant was not found to be affected by grilling [29]) and red Florina pepper, since they consist of the larger part of the AS [29][30][31]. Moreover, the results showed that the extracted oil from the salad without preservatives showed the highest (significant at p < 0.05) induction period (higher oxidation resistance), compared to the extracted one from the salad with preservatives.…”

Evaluation of physicochemical properties and microbial counts of raw and cooked low‐fat patties added with eggplant powder prepared with different drying methods

“…This is indicated that 0.5% eggplant inhibited the deterioration of protein in patties. Salamatullah et al (2021) have found that fresh and cooked EP had an ability to inhibit the growth of Staphylococcus aureus, Listeria monocytogenes, Escherichia coli, Pseudomonas aeruginosa and Candida albicans.…”