No abstract

Fish soup was usually prepared in electrical stewpot instead of traditional purple clay stewpot due to its convenience nowadays; however, fish soup prepared in electrical stewpot at a high temperature for a long time resulted in flavour deterioration. The flavour profile of crucian carp soup prepared in high temperature modes (traditional purple clay stewpot (TS) and commercial ceramic electrical stewpot (CS)) and low temperature modes (electrical stewpot with low temperature modulation modes (TM1‐TM6)) was studied by sensory evaluation, gas chromatography‐mass spectrometry (GC‐MS) and GC‐MS/olfactometry (GC‐MS/O). Results indicated that crucian carp soup prepared in TM2 (heating rate of 2.44°C/min, constant temperature time of 20 min, low temperature of 90°C, low temperature time of 60 min) had favourable sensory characteristic with stronger cooked fish and fatty aroma and lower off‐flavour. Twenty‐six odorants in crucian carp soup were identified by GC‐MS/O. Of these, 8 odour‐active compounds presented odour activity values (OAVs) greater than 1, with several aldehydes and 1‐octen‐3‐ol contributing as important odorants of crucian carp soup. TM2 samples exhibited higher OAVs in these 8 odorants compared with CS and other TM samples. The umami‐taste amino acids in TM2 accounted for a higher proportion compared to TS and CS samples. The correlation analysis between sensory characteristics and odorants through partial least squares regression (PLSR) indicated that octanal, decanal and 1‐octen‐3‐ol were significantly and positively associated with cooked fish note. Heptanal, octanal, decanal and (E,E)‐2,4‐decadienal significantly and positively linked with fatty note. (E,E)‐2,4‐Decadienal showed a significant and negative correlation with fishy odour.

The influences of four drying methods (hot air drying (HAD), vacuum freeze drying (VFD), vacuum drying (VD) and intermittent microwave combined with hot air drying (MW-HAD)) on the taste profile and flavor characteristic of Cordyceps militaris were investigated. MW-HAD samples had the highest levels of umami taste 5′-nucleotides, bitter taste amino acids, and equivalent umami concentration (EUC) value. The aroma fingerprints and differences of dried Cordyceps militaris were established by GC-MS with odor activity values (OAVs) and GC-IMS with principal component analysis (PCA). GC-MS data showed that the predominant volatiles of dried samples were aldehydes, alcohols, and ketones. VFD samples had the highest amount of total aroma compounds and C8 compounds. Moreover, 21 aroma-active components (OAVs ≥ 1) were the main contributors to the flavor of dried Cordyceps militaris. The OAVs of 1-octen-3-one and 3-octanone associated with mushroom-like odor in VFD were significantly higher than other samples. Furthermore, a significant difference in flavor compounds of four dried samples was also clearly demonstrated by GC-IMS analysis with PCA. GC-IMS analysis revealed that VFD samples had the most abundant flavor compounds. Overall, MW-HAD was an effective drying method to promote umami taste, and VFD could superiorly preserve volatiles and characteristic aroma compounds in dried Cordyceps militaris.