Coconut meat is the main raw material for coconut products processing, which is mainly obtained by importing dehusked coconut fruits in containers, and the rate of bad fruit is high in the process of transportation and storage. In order to explore the method of rapid differentiation and identification, this study used gas chromatography-ion mobility spectrometry (GC-IMS) combined with principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA) to analyze the volatile compounds in coconut meat of unstored normal dehusked fresh coconut fruits (FCM) and deteriorated dehusked coconut fruits under 25 ℃/70%, 35 ℃/80% and 45 ℃/90% (DCM-25, DCM-35 and DCM-45). The results showed that 42 volatile compounds were identified in the four coconut meat, including thirteen alcohols, five acids, eight ketones, ten esters, four aldehydes, two pyrazines and three unknown compounds. The alcohols were the most (including ethanol, butanol and propanol, etc.), followed by acids (including acetic acid and 2-methylpropionic acid, etc.), ketones (including acetone, 3-hydroxy-2-butanone and cyclopentanone, etc.), esters (including butyl caproate, ethyl acetate, butyl butyrate and ethyl butyrate, etc.), aldehydes (including 3-methylbutyraldehyde, pentalaldehyde and heptyl aldehyde, etc.) and pyrazines (2-ethyl-3-methylpyrazine). After deterioration, alcohol, acid and ketone volatile compounds increased. Thirteen characteristic volatile compounds, including 3-methylbutyral, cyclopentanone, 3-methylbutanol monomer, butanol monomer, heptaldehyde, acetone, 2-methylpropanol monomer, 2-heptanone monomer, heptanic acid, butyl butyrate monomer, ethyl acetate, ethanol dimer and 2-ethyl-3-methylpyrazine monomer, were analyzed by OPLS-DA, with variable importance in projection greater than 1. The characteristic volatile compounds in FCM were cyclopentanone and butanol monomer by differential heat map. The characteristic volatile compounds in DCM-25 were 2-heptanone monomer, butyl butyrate monomer, ethyl acetate, ethanol dimer and 2-ethyl-3-methylpyrazine monomer (mainly esters, alcohols and ketones). The characteristic volatile compounds in DCM-35 was heptanoic acid (mainly acids). The characteristic volatile compounds in DCM-45 were 3-methylbutyraldehyde, heptyl aldehyde and acetone (mainly aldehydes and ketones). This study would provide theoretical basis for the screening of deteriorated dehusked coconut fruits.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |