One of the most important Citrus species is Citrus limon (Rutaceae), also known as lemon. Phenolic acids, flavonoids, amino acids, carbs, and vitamins could be found throughout the entire lemon fruit, including the peel, seed, and pulp. However, lemon peel, a by-product of the lemon, is never fully utilised and is constantly discarded. The lemon peel was employed in this work to optimise the quantity of polyphenols, phenolic acids, and flavonoids utilising response surface methodology (RSM). A central composite design (CCD) was used in this study, and factors including ethanol concentration (70–90%), extraction temperature (45–65°C), and extraction duration (80–120 minutes) were examined. Based on the results obtained, ethanol concentrations and extraction temperatures were significantly affected the total polyphenols, phenolic acids and flavonoids content. However, the experimental data was adequately fitted with the second-order polynomial models. Based on the multi-responses optimized extraction conditions were as follows: 85.77%, 65°C and 120 minutes for ethanol concentration, extraction temperature and extraction time, respectively. This optimized condition could be useful for phenolics extraction from lemon peel.
Key words: Citrus limon, response surface methodology, polyphenol, phenolic acid, flavonoid
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