Alkali Extraction of Phenolic Compounds from Tomato Peel: Optimization of Extraction Conditions and Investigation of Phenolic Profile by LC-MS/MS

Abstract

With the increasing world population, the food need of humanity is increasing proportionally. Agricultural wastes constitute an important potential for the global economy as they contain components that are less preferred to be consumed as food due to their low bioavailability due to their indigestion in the human body or due to their sensory properties, but that may be beneficial to human health such as antioxidant substances and antimicrobial agents. The benefits of using these wastes in terms of economy and reducing environmental pollution are obvious. Tomato, which is one of the most used agricultural products in our country and the world, is processed by removing its skins in the processing of many products. Tomato skins cause serious environmental problems and economic losses unless they are valorized. In this regard, this study aims to optimize the extraction efficiency, the antioxidant capacity, and total phenolic content of the tomato peel extract according to the independent variables of temperature and time, while the alkaline extraction process applied to tomato skins is cheap and industrially applicable. Using response surface methodology, the highest extraction yield (28.77 g/100 g dry extract), total phenolic content (3819.32 mg GAE/100 g dry extract), and total antioxidant capacity (2737.82 µmoL Trolox/100 g dry extract) were obtained under extraction conditions at 100°C for 5.26 h. According to LC-MS/MS results, tomato skins treated with alkali contain various phenolic acids and some flavonoids. The phenolic component found in the highest amount in the tomato peel extract was determined as p-coumaric acid (429.99 ± 38.53 mg/100 g dry extract). Other important phenolic components are ferulic acid (12.44 ± 2.06); 4-hydroxy benzoic acid (7.13 ± 1.01) and vanillin (2.47 ± 0.22) mg/100 g dry extract.

Enhancing Oxidative Stability of Nigella Sativa Oil with Some Agro-Industrial Wastes Extracts and its Utilization in Mayonnaise

“…Kaempferol blocks the translation of viral proteins (Tsai et al, 2011). The p-coumaric acid was 429.99 ± 38.53 mg/100 g dry extract as the highest amount of acid in the tomato peel extract (Esmer et al, 2022). The presence of phenolic and the other bioactive compounds possibly explains the antioxidant potential found in all extracts.…”

“…Nincevic-Grassino et al (2020), found that the phenolic content of tomato peels was 2626 and 2866 mg GAE /100 g which were extracted for 6 h with 96% and 70% hot ethanol, respectively. Also, Esmer et al (2022), reported that the total phenolic content of the tomato by product extract was 3819.32 mg GAE/100 g dry extract using extraction conditions at 100 °C for 5.26 h. These variations in total phenolic content may be caused by the plant variety, the environmental conditions, the harvest time fruit maturity and the method of analysis. 2), which showed the phenolic and the other bioactive compounds and their percentage of each ethanolic extract of the studied waste materials.…”

Optimization of Alkali Treatment for Production of Fermentable Sugars and Phenolic Compounds from Potato Peel Waste Using Topographical Characterization and FTIR Spectroscopy

“…Alkali and alkali-assisted steam treatment to extract useful compounds from different plant biowastes are methods of choice in select situations to obtain value added products [40][41][42][43]. The treated substrates are compared with their respective controls by SEM to assess the level of polymeric destruction [44][45][46].…”