## 3 Results and Discussion
Flavor compounds, such as pyrroles, thiophenes, furrans and pyrazines, are formed through the generation of various volatile compounds in this process [66]. The fresh garlic cloves contained smaller amounts of green grass, floral and fruity aroma substances, and with the aging process, substances such as methyl acetate, 2-octanone, 1-hydroxy-2-propanone and (E,E) 2,4-decadienal improved the smell of the black garlic. Figure 5 shows the aromatic profile in a PCA plot based on the VOCs in the samples. The electronic taste sensor reactivity values of the tested samples are shown in Figure 5. Additionally, to the best of our knowledge, the taste profile of the garlic and black garlic was for the first time analyzed on an electronic tongue, which is a novelty of the current work. Sourness (AHS) increased after the fermentation process (1.90-7.30), and the values between black garlic samples were similar between groups. In the case of umami (NMS), taste was enhanced after thermal process and increased from 1.90 (WG) to 7.00-7.40 in BG and BG-P, respectively. According to the results obtained by [PERSON] and [PERSON] (2022) [67], lyophilized chives (Allium), which contain free amino acids, may enhance the umami taste in the product. The saltiness (CTS) decreased after the fermentation process, from 9.30 to 6.80 (BG-S), 5.50 (BG-P) and 5.20 (BG-C). The fresh garlic showed a strong bitter taste (SCS), and with a thermal process, the bitter taste strongly decreased, which may be due to the decrease of the total sulfide compounds, which tended to decrease during the thermal process. As previously reported, BG products in taste are very mild with sweet and sour tones, and fructologosaccharides contribute to the sweet taste of black garlic [18; 27]. The taste profiles (fingerprints) were obtained using a PCA based on the reactivity of all the sensors, which was derived from the e-tongue analysis results of the individual samples. The analysis results are shown in Figure 6. A total contribution rate of over 97% suggested the feasibility of the method. The variance contribution rate of PC1 was 99.50%, and PC2 was 0.26%. The classification of the groups showed that samples WG and BG were classified correctly. According to the PCA chart, the results from the e-tongue were able to completely distinguish the flavor of fresh and processes garlic cloves. Therefore, the black garlic samples (BG-C, BG-S, BG-P) shown on the \(x\)-axis had quite similar taste profiles. However, the BG-C and BG-P showed slightly different taste profiles from BG-S.  
Figure 5: Radar map of e-tongue data for fresh and black garlic. WG—white garlic, BG-C—black garlic cloves, BG-P—black garlic powder, BG-S—black garlic spreading paste. The samples of WG cloves were positive along the \(y\)-axis and negative along the \(x\)-axis, indicating a greater diversity from BG samples. Therefore, an electronic tongue can also be used to distinguish white garlic and black garlic samples. The results based on the e-tongue measurement were significantly correlated with the human sensory evaluation scores, indicating that the e-tongue can be utilized to characterize the flavor of garlic products or other food types. According to the results from the research, the chemical processes occurring during the long-term heat treatment of garlic as well as its further processing (production of black garlic powder or spreading paste) significantly changed the physicochemical and bioactive properties (such as the content of polyphenols, antioxidant potential) or the content of the volatile compounds. They changed the aroma and taste profile of the products produced in this way, which gained completely different organoleptic or sensory properties and characteristics. The caramelization, enzymatic and non-enzymatic browning reactions taking place during the aging of garlic and the products formed as a result of the Maillard reaction also significantly changed the color parameters of processed garlic [19; 20; 68].