Investigation of the Volatile Profile of Red Jujube by Using GC-IMS, Multivariate Data Analysis, and Descriptive Sensory Analysis

Abstract

The aroma characteristics of six red jujube cultivars (Jinchang-'JC', Junzao-'JZ', Huizao-'HZ', Qiyuexian-'QYX', Hetiandazao-'HTDZ', and Yuanzao-'YZ'), cultivated in Xinjiang Province, China, were studied by E-nose and GC-IMS. The presence of acetoin, E-2-hexanol, hexanal, acetic acid, and ethyl acetate played an important role in the classification results. JC, JZ, HZ, and YZ were different from others, while QYX and HTDZ were similar to each other. HZ had the most abundant specific VOCs, including linalool, nonanoic acid, methyl myristoleate, 2-acetylfuran, 1-octen-3-one, E-2-heptenal, 2-heptenone, 7-octenoic acid, and 2-pentanone. HZ had higher intensity in jujube ID, floral, sweet, and fruity attributes. Correlation analysis showed that jujube ID (identity) might be related to phenylacetaldehyde and isobutanoic acid that formed by the transamination or dehydrogenation of amino acids; meanwhile, the sweet attribute was correlated with amino acids, including threonine, glutamic acid, glycine, alanine, valine, leucine, tyrosine, phenylalanine, lysine, histidine, and arginine.

Keywords: E-nose; GC-IMS; aroma distinction; red jujube; sensory attributes.

Figure 1

The response data of sensors in E-noses on volatiles of the six red jujube cultivars in Xinjiang Province, China (Jinchang—‘JC’, Junzao—‘JZ’, Huizao—‘HZ’,Qiyuexian—‘QYX’, Hetiandazao—‘HTDZ’, and Yuanzao—‘YZ’). Lower letters (a–f) correspond to significant differences at p < 0.05.

Figure 2

Principle component analysis (PCA) and loading plot of E- nose data for the six red jujube cultivars in Xinjiang Province, China (Jinchang—‘JC’, Junzao—‘JZ’, Huizao—‘HZ’,Qiyuexian—‘QYX’, Hetiandazao—‘HTDZ’, and Yuanzao—‘YZ’).

Figure 3

Semi-quantitative results of GC-IMS analysis of the volatiles in six red jujube cultivars taken from Xinjiang Province, China (Jinchang—‘JC’, Junzao—‘JZ’, Huizao—‘HZ’,Qiyuexian—‘QYX’, Hetiandazao—‘HTDZ’, and Yuanzao—‘YZ’). Lower letters (a–f) correspond to significant differences at p < 0.05.

Figure 4

Heatmap analysis of volatiles taken from GC-IMS of the six red jujube cultivars in Xinjiang Province, China (Jinchang—‘JC’, Junzao—‘JZ’, Huizao—‘HZ’,Qiyuexian—‘QYX’, Hetiandazao—‘HTDZ’, and Yuanzao—‘YZ’).

Figure 5

Volatiles with variable importance in projection (VIP) scores over 1 in the six red jujube cultivars from Xinjiang Province, China (Jinchang—‘JC’, Junzao—‘JZ’, Huizao—‘HZ’,Qiyuexian—‘QYX’, Hetiandazao—‘HTDZ’, and Yuanzao—‘YZ’).

Figure 6

Correlation analysis among sensory attributes and fatty acids, amino acids, organic acids, sugars and VOCs (VIP score > 1) of the six red jujube cultivars from Xinjiang Province, China.