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In this research, the compositional changes of key aroma compounds of ‘Guire No. 82’ mangoes before and after dehydration at green, semi-ripe and fully ripe stages were assessed by gas chromatography-mass spectrometry (GC-MS). The results revealed that the key aroma compounds of fresh fruit in ‘Guire No. 82’, such as β-pinene, 2-carene, β-myrcene, 3-hexene-1-alcohol, etc., possessed the highest content in the green ripening stage, which also suffer a great loss accompanying with the processing, and even not at all for decyl aldehyde. Meanwhile, the content of β-pinene and β-myrcene gradually decreased with the mango ripening, but the content of ethyl caproate and ethyl butyrate increased and reached the middle value at the half-ripe stage, and its content remained the highest after processing. Additionally, the content of ethyl hexanoate, ethyl butyrate and phenethyl alcohol reached the peak value at the full ripening stage, however, the loss of its content after processing was also very obvious, especially for ethyl hexanoate. O-cymene was only detected at the half-ripening stage, which remained after processing. The content of β-ionone was the highest in the half-ripening stage and remained at the highest level after processing. From the analysis of main aroma components, the 14 main aroma components of half-ripe mango did not disappear after processing, and the retention rate of main aroma components (original fruit flavor) reached 100%. Therefore, compared with other ripening stages, the key aroma compounds of mangoes processed into original dried fruit at the half-ripening stage of ‘Guire No. 82’ were better than those of the other two stages.

In order to study the variation of volatile flavor components of virgin coconut oil during storage at room temperature. Headspace solid phase microextraction and gas chromatography-mass spectrometry (HS-SPME-GC-MS) was used to analyze virgin coconut oil in different oxidation stages. The results showed that 40 kinds of volatile components (8 common components) were identified, mainly including esters, aldehydes, ketones and acids. Relative odor activity value (ROAV) analysis showed that hexanal, 2-heptanone, δ-hexanolactone, nonanal, ethyl octanoate, δ-octalactone, 2-undecone, ethyl caprate and δ-decalactone were the key flavor substances in the storage process of virgin coconut oil at normal temperature. Combining principal component analysis (PCA) and partial least squares discrimination analysis (PLS-DA), a discriminant model for different storage periods of virgin coconut oil was established, which showed that in addition to the contents of different compounds (ketones, esters and acids) could be used as indicators to simply distinguish the storage period of virgin coconut oil, at least six key volatile components (2-heptanone, 2-hexanone, δ-hexanolactone, hexanal, caproic acid and δ-octalactone) could also be used to evaluate the oxidation of virgin coconut oil. Related research provided theoretical reference for the evaluation of virgin coconut oil flavor quality and degree of oxidation, and the findings would be conducive to the development of a new method for the identification of virgin coconut oil products with different degrees of freshness.

In this study, virgin coconut oil gels with different hydroxypropyl methylcellulose (HPMC) and xanthan gum (XG) concentrations were prepared by the emulsion template method. The particle size distribution, microstructure observation, rheological behavior, oil retention and crystallinity were used to investigate the influence of HPMC and XG concentration on the formation and physical properties of virgin coconut oil emulsion and oleogel. The particle size analysis and microstructure results showed that high-concentration HPMC had better emulsification performance, and a stable emulsion with smaller oil droplet size was obtained. The change of XG concentration had no significant effect on the oil droplet size. The rheological results showed that the mechanical strength of emulsions and oleogels increased with the increase of HPMC or XG concentration, and all oleogels showed a time-dependent and structural recovery. The oil loss results showed that the increase in HPMC concentration had a particularly significant impact on the oleogel oil loss, the change range was reduced from 19.6% to 3.6%. The increase in XG concentration also reduced the oil loss from 9.62% to 4.4%. However, the change of HPMC and XG concentration had no significant effect on the XRD pattern of oleogels. This study provides a theoretical basis for the construction of virgin coconut oil gel, and also provides a reference for its practical application.

An emulsion template method was an effective way to prepare oleogels. However, there were few reports on how hydroxypropyl methylcellulose-pectin (HPMC-PC) mixtures affected the physicochemical properties of the obtained oleogels. In this study, the oleogels were prepared by an emulsion template method. The influences of HPMC and PC concentrations on the formation and physical properties of the emulsions and oleogels were investigated, by analyzing particle size distribution, microstructure, rheological test, oil loss, and crystallinity. The results of particle sizes and microstructure showed that a high concentration of HPMC and PC exhibited a better emulsification performance. The rheological tests indicated that a high concentration of HPMC and PC contributed to an increase in the mechanical strength of emulsions and oleogels. Moreover, an increase in an HPMC and PC concentration was beneficial to reduce the oil loss of oleogels. However, the change of HPMC and PC concentrations had no significant effect on the X-ray diffraction pattern of oleogels. This study could provide a theoretical basis for the construction of polysaccharide-based oleogels.