Comparative and variability analysis of different drying methods on phytochemical, antioxidant and phenolic contents of Ficus auriculata Lour. Fruit

Abstract

IntroductionRoxburgh Fig is a deciduous evergreen tree grown in a tropical region with wild edible fleshy fruits. They can be eaten raw or cooked, used in jams, juice and curries. The drying of fleshy fruits using thermal processing is an important method to preserve nutraceuticals. This study describes the effects of sun, hot air oven and microwave drying method on Ficus auriculata fruit polyphenol contents. MethodsThe fleshy fruits were dried and the extraction was made out using 80% methanol with a sonicator. The HPLC-DAD analysis was performed using an analytical instrument equipped with LC 20 AP binary solvent pump, SPD N 20A diode array detector with C18 column with 5 µm size and 4.6 × 250 mm dimension. Principle component analysis (PCA) was performed to analyze the contribution of independent variables. The microstructure of dried fruit samples was observed at 200X magnification at an acceleration voltage of 20kV in SEM. ResultsThe results revealed that the carbohydrates (275.34 ± 5.57mg GE/ g sample), proteins (243.07 ± 4.17mg BSAE/ g sample) and amino acids (21.25 ± 0.82mg LE/ g sample) were higher in hot-air oven dried fruit. The antioxidant activity was reported higher in microwave dried and hot-air oven dried samples due to the moderate distribution of secondary metabolites. The HPLC-DAD polyphenol quantification revealed a higher amount of gallic acid (7.73 mg/ g sample) in HD dried fruit and caffeic acid (6.73 mg/ g sample) and rutin (8.33 mg/ g sample) contents in the MD dried extracts. The SD and HD contributed 94.31% and 5.01% of the variance in the phytochemical components, respectively. The microstructures of the dried samples resulted that the microwave drying showed a loser porous structure gives more shrinkage for preservation. ConclusionThus, microwave drying should be an optimal method for obtaining dried roxburgh fig with high nutritional value.