Microwave Assisted Extraction Of Bioactive Compounds Review PDF Download

"Food safety and the management of organic waste and loss, such as food waste, are problems of global interest. Fruit and vegetable by-products are listed as one of the main food wastes; among these wastes, there is a large number of vegetables of high global production, such as broccoli, however, broccoli florets are the ones that are commonly consumed in food, causing the broccoli by-products, such as stems, and leaves to be discarded. Broccoli by-products contain significant amounts of bioactive compounds, which are chemical compounds with beneficial properties for human consumption since they have antioxidant, antimicrobial, and anti-inflammatory properties. Among the bioactive compounds, phenolics are of great interest nowadays and their importance is growing.Phenolic compounds can be recovered from broccoli by-products through extraction techniques. Microwave-assisted extraction is an unconventional extraction technique that allows various compounds to be recovered, such as phenolic compounds from plants, in short periods of time, with high efficiency. However, there is not enough research regarding the optimization and validation of microwave-assisted extraction to recover phenolic compounds from broccoli by-products.Therefore, the purpose of this master's project was to perform the optimization of microwave-assisted extraction to recover phenolic compounds from broccoli by-products, which include stems and leaves, and compare them with the edible parts, known as florets. As a first step, the effect of three operational variables such as time, temperature, and methanol concentration in the microwave extraction process was evaluated, these variables were selected according to the literature review. The variables were optimized through a Response Surface Analysis to obtain the maximum total phenolic response of the broccoli stems, leaves, and florets. As a result, the optimal variables were determined to be 10 min, 73.27°C, and 80% methanol for broccoli leaves, 15.9 min, 74.45°C, and 74.54% methanol for broccoli stems, and 18.9 min, 75°C, and 80% methanol for broccoli florets.The second stage of the project involved determining antioxidant activity, identifying the main phenolic acids in broccoli extracts, and comparing microwave and maceration extraction methods. Broccoli stems had the lowest antioxidant activity and total phenolic content, while leaves had the highest. In addition, when compared to maceration extraction, microwave extraction increased phenolic production in all broccoli extracts. Finally, the last stage of this thesis consisted of the analysis of the behavior of acetone, water, and methanol, as polar compounds, and hexane, as a non-polar compound, in the microwave extraction process of broccoli stems, florets, and leaves. The results showed that polar solvents favor the extraction of phenolic compounds from broccoli extracts; however, some solvents such as methanol and acetone can degrade the compounds if they exceed 85°C of temperature.In general, this project offers a comprehensive review of different extraction techniques of bioactive compounds from several fruit and vegetable by-products; In addition, it provides a broad view of the behavior of the main variables in the microwave extraction of phenolic compounds from broccoli, which serves as a basis for the extraction of phenols in this type of plants"--