Comparative Study between Parts of Fennel (Foeniculum vulgare Mill.) for Taste and Flavor Properties

Abstract

Our research investigated sensory and chromatographical characteristics using an electronic tongue (E-tongue), electronic nose (E-nose), and gas chromatography/mass spectrometry (GC/MS). The characteristics of taste and flavor in parts of the fennel were measured by a non-destructive method and pattern analysis. The results of the E-tongue showed that the fennel seed had the highest sensor value of umami taste (UMS) and sourness taste (SRS) at 8.7 and 8.4, respectively. On the other hand, the sensor value of saltiness (STS) in the seed was detected at 4.5, which was lower compared to portions of the stem and bulb at 6.0 and 7.5, respectively. The E-tongue and E-nose principal component analysis (PCA) showed that the principal component 1 (PC1) represented 82.36% variance and PC2 represented 17.64% variance. The fennel bulb has been located on the first quadrant, with the highest sensor values of STS and the highest content of d-valerolactone, trans-anethole, 2-octanone, and 3-mercapto-2-pentanone. The fennel seed has been located on the second quadrant, with the highest sensor values of UMS and SRS, as well as 3-methyl nonane content. The fennel stem has been located on the fourth quadrant, which has the highest content of α-pinene. In the GC-MS analysis, a total of 129 volatile compounds were identified, which include 7 acids and esters, 20 alcohols, 16 aldehydes, 70 hydrocarbons, 6 heterocyclics, and 10 ketones in the sample sets. An analysis of odor active compounds showed p-anisic aldehyde elicits floral and fennel odors at 3 and 2 odor intensity in the stem and seed, respectively. α-Pinene, 5-methyl-3-(1-methylethylidene)-1,4-hexadiene, and trans-anethole elicit fennel odors. Specifically, trans-anethole was detected in all samples.

A comprehensive study for taste and odor characteristics using electronic sensors in broccoli floret with different methods of thermal processing

“…After the extraction of taste components in broccoli, the extracted broccoli sample was subjected to an e‐tongue module, and e‐tongue analysis was repeated six times for each sample. The five basic taste sensor responses were converted to taste sensor values ranging from 1 to 12, and the general taste distribution was given in a descriptive manner (Boo et al, 2020; Hong et al, 2021).…”

“…The oven temperature was held at 40°C for 5 s, increased to 270°C at a rate of 4°C/s, and maintained for 30 s. Analyses of volatiles were conducted by Kovat's index library-based AroChembase (Alpha MOS), and volatiles corresponding to each peak were identified. (Boo et al, 2020;Hong et al, 2021).…”

“…Recently, the usage of novel detection instruments for flavor compounds has been increasing. For instance, flavor compounds were identified using electronic nose (e‐nose) and electronic tongue (e‐tongue) (Dong et al, 2019; Hong et al, 2021; Liu et al, 2017).…”

“…Because of the advantages of e‐tongue, several studies were conducted: different parts of fennel were analyzed using e‐tongue (Hong et al, 2021) and different sizes of radish were analyzed using e‐tongue as well (Boo et al, 2020). Furthermore, various recent studies for the taste and flavor characteristics using e‐tongue and e‐nose have been conducted (Boo et al, 2020; Dong et al, 2019; Hong et al, 2021; Yin et al, 2021; Zhang et al, 2021). However, most previous studies have represented e‐tongue and e‐nose results, respectively.…”

“…Taste characteristics are also an important factor in evaluating food quality (Dong et al, 2019; Yin et al, 2021), and e‐tongue can investigate the taste characteristics in Brassicaceae vegetables and other vegetables (Boo et al, 2020; Hong et al, 2021). e‐tongue has been used for quality control in food products.…”