Physico-chemical study of steroids from different matureness corn silk material

Peng Li,Sergii Kalytchuk,Lubomí­R Lapčí­K,Barbora Lapčí­Ková

doi:10.5219/1144

Abstract

This study shows an ultrasonic assisted extraction procedure of steroids from corn silk (CS). The total steroids contents were positively correlated with the ultrasonic assisted extraction time. The extracted steroids contents varied according to the different maturity stages of CS. There were three tested CS maturity stages: silking stage (CS-S), milky stage (CS-M) and mature stage (CS-MS). The β - sitosterol standardization method with 530 nm wavelength colorimetric measurements were applied to determine the content of extracted steroids. Measured steroids concentrations range were from 38.3 × 10-3 mg.mL-1 to 368.9 × 10-3 mg.mL-1 in different extraction time and CS maturity stages. The highest concentration of steroids, 368.9 × 10-3 mg.mL-1 was found in CS-MS sample with the 75 minutes ultrasonic extraction time. The fluorescence mapping techniques were used to confirm the existence of steroids. The thermal analysis illustrated a typical multistep decomposition process for the CS-S, CS-M and CS-MS samples. Two endothermic peaks were found: The first one was 54.3 °C for CS-S and CS-MS, 60.2 °C for CS-M, the second one, 397 °C (CS-MS), 415.1 °C (CS-M) and 419.7 °C (CS-S) attributed to the total thermal decomposition. The observed exotheric process found at 524 °C corresponded to CS-MS sample decomposition. The optimal ultrasonic-assisted extraction time for all samples under study CS-S, CS-M and CS-MS was about 75 minutes and the optimal steroids extraction contents obtained were 92.8 × 10-3 mg.mL-1 (CS-S), 124.2 × 10-3 mg.mL-1 (CS-M) and 368.9 × 10-3 mg.mL-1 (CS-MS) respectively.

Highlights

Corn silk (CS) can be defined as the dried thrum and stigma of Zea mays L. which is cheap and high yielding
This study focuses on the extraction procedures evaluation, kinetics and the maturity stage effects on the CS extracts, allowing in more detailed knowledgement for the developing novel nutrition or health care products to contribute to the human and veterinary applications
For the sample CS-M and CS-MS, TG data exhibited the first step decomposition of 5.9% and 10.04% in the same temperature range as CS maturity stages: silking stage (CS-S) followed by the total weight loss of 65.5% and 83.88% in the temperature range of 30 to 550 °C, which indicated the CS-MS contains the most thermally labile substances compared with CS-S and CS-M

Summary

Introduction

Corn silk (CS) can be defined as the dried thrum and stigma of Zea mays L. (corn) which is cheap and high yielding. The optimal ultrasonic-assisted extraction conditions were identified as an amplitude of 61 μm and an extraction time of 17 min which resulted the recovery of 1102 μg steroidal alkaloids per g dried potato peel. The optimization of extraction conditions, steroids properties comparison and the determination of the steroids kind according to the various maturity stages of corn silk are rarely reported.

Results

Conclusion