Comparative Analysis and Development of a Flavor Fingerprint for Volatile Compounds of Vegetable Soybean Seeds Based on Headspace-Gas Chromatography-Ion Mobility Spectrometry.

Fengjie Yuan,Hangxia Jin,Qinghua Yang,Xujun Fu,Longming Zhu,Xiaomin Yu

doi:10.3389/fpls.2021.768675

Abstract

Evaluating the volatile compounds and characteristic fingerprints of the core cultivars of vegetable soybean would provide useful data for improving their aroma in the breeding programs. The present study used headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS) to evaluate the volatile compounds of vegetable soybean seeds at a specific growth stage. In total, 93 signal peaks were identified, 63 compounds qualitatively, with 14 volatile flavor compounds providing multiple signals. The 63 volatile compounds consisted of 15 esters, 15 aldehydes, 13 alcohols, 15 ketones, one acid, and four other compounds. The peak intensity of most of the volatile compounds varied greatly between the core cultivars. The alcohols and aldehydes determined the basic volatile flavor of the vegetable soybean seeds. Volatile flavors were determined by their respective esters, ketones, or other components. Characteristic fingerprints were found in some core vegetable soybean cultivars. Four cultivars (Xiangdou, ZHE1754, Zhexian 65018-33, and Qvxian No. 1) had pleasant aromas, because of their higher content of 2-acetyl-1-pyrroline (2-AP). A principal component analysis (PCA) was used to distinguish the samples based on the signal intensity of their volatile components. The results showed that the composition and concentration of volatile compounds differed greatly between the core cultivars, with the volatile flavor compounds of soybeans being determined by the ecotype of the cultivar, the direction of breeding selection, and their geographical origin. Characteristic fingerprints of the cultivars were established by HS-GC-IMS, enabling them to be used to describe and distinguish cultivars and their offspring in future breeding studies.

Highlights

The peak signal distributions of the different samples were very similar, but the signal intensity varied, indicating that the content of volatile flavor compounds differed among the samples
In a further comparison using 2D spectra (Figure 1B), the reactive ion peak (RIP) is represented by the red vertical line at the horizontal coordinate of 1.0, with each point on the right side of RIP representing the type of volatile compound, with the retention time of most signals appearing between 100 and 600 s
GC-O-MS is a powerful tool for extracting aroma-active compounds from the complex mixtures, because of repetitive time-consuming labor, this method is not ideal for the rapid detection of volatile organic compounds (VOCs) in the plant-based products (Wang et al, 2020)

Summary

Introduction

Merr.) is the most important crop cultivated worldwide It is a major source of protein and vegetable oil for human and animal consumption and contains several phytochemicals, such as isoflavones and phenolic compounds. Apart from its macronutrients and micronutrients, the dark green color of the vegetable soybean at maturity, its large seed size, soft texture, sweetness, and less beany flavor differentiate it from the regular soybean (Saldivar et al, 2011). Of these attributes, flavor often has the greatest influence on consumer acceptance and behavior. Determining the diversity of these flavor compounds and their contribution to the volatile flavor of vegetable soybean seeds is invaluable for assessing the quality of the soybean at the edible stage (Castada et al, 2019)

Methods

Results

Conclusion