In order to screen for a proper baking condition to improve flavor, in this experiment, we analyzed the effect of baking on the flavor of defatted tiger nut flour by electronic tongue (E-tongue), electronic nose (E-nose) and headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC-MS). According to E-tongue and E-nose radar plots and principal component analysis (PCA), baking can effectively change the taste and odor of defatted tiger nut flour, and the odors of samples with a baking time of >8 min were significantly different from the original odor of unbaked flour. Moreover, bitterness and astringency increased with longer baking times, and sweetness decreased. HS-SPME-GC-MS detected a total of 68 volatile organic compounds (VOCs) in defatted tiger nut flour at different baking levels, and most VOCs were detected at 8 min of baking. Combined with the relative odor activity value (ROAV) and heat map analysis, the types and contents of key flavor compounds were determined to be most abundant at 8 min of baking; 3-methyl butyraldehyde (fruity and sweet), valeraldehyde (almond), hexanal (grassy and fatty), and 1-dodecanol, were the key flavor compounds. 2,5-dimethyl pyrazine, and pyrazine, 2-ethylalkyl-3,5-dimethyl- added nutty aromas, and 1-nonanal, 2-heptanone, octanoic acid, bicyclo [3.1.1]hept-3-en-2-ol,4,6,6-trimethyl-, and 2-pentylfuran added special floral and fruity aromas.

In this study, using gas chromatography-mass spectrometry (HS-SPME-GC-MS), electronic nose (E-nose), high performance liquid chromatography (HPLC), and electronic tongue (E-tongue) to analyze the effect of ultra-high pressure (UHP) synergistic enzymatic hydrolysis on the flavor compounds of enzymatic hydrolysates of S. rugoso-annulata. The results demonstrated that 38 volatile flavor substances were identified in the enzymatic hydrolysates of S. rugoso-annulata treated at atmospheric pressure and 100, 200, 300, 400, and 500 MPa, mainly 6 esters, 4 aldehydes, 10 alcohols, 5 acids, and 13 other volatile flavor substances, and the most kinds of flavor substances reached 32 kinds when the pressure was 400 MPa. E-nose can effectively distinguish the overall changes of enzymatic hydrolysates of S. rugoso-annulata treated with atmospheric pressure and different pressures. There was 1.09 times more umami amino acids in the enzymatic hydrolysates at 400 MPa than in the atmospheric pressure enzymatic hydrolysates and 1.11 times more sweet amino acids at 500 MPa than in the atmospheric pressure enzymatic hydrolysates. The results of the E-tongue indicate that the UHP treatment increased umami and sweetness and reduced bitterness, which was also confirmed by the results of amino acid and 5′-nucleotide analysis. In conclusion, the UHP synergistic enzymatic hydrolysis can effectively improve the overall flavor of the enzymatic hydrolysates of S. rugoso-annulata; this study also lays the theoretical foundation for the deep processing and comprehensive utilization of S. rugoso-annulata.