Prediction of Bioactive Properties of Walnut Green Husks Using FT-IR Spectroscopy

Walnut is a widely consumed, nutritive and healthy crop in the world. China, the US, and Iran are the leading countries of walnut production, and Turkey is among the main producers ranking fourth with 180.000 tons of production rate. Walnut green husk is a valuable agricultural by-product that is commonly used in traditional medicine for alleviating pain and treating skin diseases related to its antioxidant properties and health benefits. This study aimed to find the effect of solvent type on extraction of bioactive compounds and to predict the extraction effects in rapid and reliable method such as Fourier transform infrared (FT-IR) spectroscopy. Solvent efficiency was evaluated using different polarity solvents such as water, methanol, ethanol, acetone and aqueous solutions of methanol, ethanol and acetone for the extraction of walnut green husks. Analysis of variance results revealed that there was a significant difference among the total phenolic contents and antioxidant activities of different extracts. Antimicrobial activity analysis demonstrated that water extracts showed higher activity against Staphylococcus aureus. According to the results of partial least squares (PLS) regression analysis to predict the total phenol content and antioxidant capacity of extracts, R2 values of calibration and cross validation models were higher than 97% with root mean square error of calibration (RMSEC) and root mean square error of cross validation (RMSECV) values ranging from 3.03 to 5.35. It can be concluded that PLS models had high predictive capability