Comparative Extraction of Pectic and Polyphenols from Mexican Lime Pomace and Bagasse

Mexican lime bagasse and pomace are rich in pectin and they also represent an important source of value-added compounds such as polyphenols. Two different options for the combined recovery of pectin and phenolic compounds from Mexican lime bagasse and pomace, two byproducts of industrial lime processing, were developed. Conventional and microwave-assisted extraction methods were used. All pectic extracts presented a degree of esterification in the range of 70%. Pomace extracts had the higher pectin yield and the lower polyphenol content. Among the bioactive compounds identified by HPLC were two flavonones, naringin and hesperidin, all compounds were present in low concentration in the pectic extracts. Microwave pectic extracts presented depolymerization, as observed by molecular weight determination (12 KDa) and compared against conventional pectic extracts which presented a molecular weight of 670 KDa. The film forming capacity of pectic extracts was also evaluated. Antioxidant activity of pectic extracts was also assessed by three different methods; all extracts showed a better activity in Fe²⁺ chelating assay (62.85-73.32%) and lipid oxidation inhibition (63.07-72.28%) than in DPPH radical inhibition (5.32-6.65%). These findings indicate a correlation between the amount of phenolic compounds and the antioxidative capacity. Conventional pectic extracts from Mexican lime bagasse and pomace presented bioactive compounds with potential application for edible films and coatings in food industry.