Changes in the Volatile Components of Candied Kumquats in Different Processing Methodologies with Headspace–Gas Chromatography–Ion Mobility Spectrometry

Abstract

The effects of two different processing methods on the volatile components of candied kumquats were investigated via headspace–gas chromatography–ion mobility spectrometry (HS–GC–IMS). The characteristic volatile fingerprints of fresh kumquats (FKs), vacuum sugaring osmosis combined with hot-air drying kumquats (VS-ADKs), and atmospheric pressure sugaring osmosis combined with hot-air drying kumquats (AS-ADKs) were established using 3D topographic plots. From the fingerprints, 40 signal peaks for 22 compounds were confirmed and quantified in all types of kumquats, namely, two terpenes, four esters, seven aldehydes, three ketones, and six alcohols. 3-Pentanone was identified as the major component of FKs; followed by 1-hexanol and the Z-3-hexen-1-ol dimer. The hexanal dimer, 2-hexen-1-ol, and the ethyl acetate dimer were the major markers of VS-ADKs. Benzaldehyde and furfurol were the prominent constituent parts of AS-ADKs. Compared with that in FKs, the pentanal and dimethyl ketone contents of VS-ADKs and AS-ADKs exhibited a dramatic increase (p < 0.05). By contrast, the change in ethanol dimer tended to decrease (p < 0.05). Principal component analysis (PCA) clearly showed that the samples, which were distributed in a separate space could be well-distinguished. Furthermore, the similarity of different processed kumquats and their corresponding volatile components was demonstrated via heat map clustering analysis. The results confirmed the potential of HS–GC–IMS-based approaches to evaluate processed kumquats with various volatile profiles.

Characterization and Biological Activities of Seed Oil Extracted from Berberis dasystachya Maxim. by the Supercritical Carbon Dioxide Extraction Method

“…The normalized signal intensity of esters in BDSO extracted by the SC-CO 2 method increased markedly, which is consistent with the observation by Hu et al [46]. The increment of ethyl acetate content in BDSO extracted by the SC-CO 2 method was more accentuated that that in BDSO extracted by the PEE method, and the content of ethyl acetate in the former was approximately 2.2 times higher than that in the latter.…”

“…The increases in the intensities of benzaldehyde and 3-methylbutanal in BDSO extracted by the PEE method were much higher than those in BDSO extracted by the SC-CO 2 method, and the increases were more accentuated with the increase in temperature. This observation could be explained by the Strecker degradation of isoleucine, which produces benzaldehyde and 3-methylbutanal during the Maillard reaction in BDSO obtained by PEE [44,46]. The signal intensity of n-nonanal in BDSO obtained by the PEE method was higher than that in BDSO obtained by the SC-CO 2 method; a similar trend was also observed in benzaldehyde.…”

Influence of temperature on storage characteristics of different rice varieties

“…In addition, the combination of IMS and other tools (Ultraviolet / Gas chromatography) is a more effective method, which can maximize its advantages and produce better analysis results. In recent years, GC‐IMS has been widely used in the researches of volatile compounds in foods, such as matsutake (Li et al., 2019), hulless barley (Zhao & Shen, 2019), egg (Cavanna et al., 2019), kumquats (Hu et al., 2019), olive oils (Gerhardt et al., 2019), and silver carp (Jia et al., 2019). However, the flavor changes of rice during storage is a complex process, and GC‐IMS is rarely used to monitor this process currently.…”

Changes in water state, distribution, and physico‐chemical properties of preserved kumquats during different processing methods

“…Water is a relatively essential component in fruit that has a significant effect on the characteristics of the processing fruit snacks. As a kind of semidried food, preserved kumquats contain finite water content that prevents from microbial infection and maintains good taste and flavor at the same time (Hu et al, 2019). Therefore, the real‐time nondestructive monitoring of the water content and state is essential for preserved kumquat processing.…”