Electronic Nose Technologies in Monitoring Black Tea Manufacturing Process

Abstract

<jats:p>“Tea” is a beverage which has a unique taste and aroma. The conventional method of tea manufacturing involves several stages. These are plucking, withering, rolling, fermentation, and finally firing. The quality parameters of tea (color, taste, and aroma) are developed during the fermentation stage where polyphenolic compounds are oxidized when exposed to air. Thus, controlling the fermentation stage will result in more consistent production of quality tea. The level of fermentation is often detected by humans as “first” and “second” noses as two distinct smell peaks appear during fermentation. The detection of the “second” aroma peak at the optimum fermentation is less consistent when decided by humans. Thus, an electronic nose is introduced to find the optimum level of fermentation detecting the variation in the aroma level. In this review, it is found that the systems developed are capable of detecting variation of the aroma level using an array of metal oxide semiconductor (MOS) gas sensors using different statistical and neural network techniques (SVD, 2-NM, MDM, PCA, SVM, RBF, SOM, PNN, and Recurrent Elman) successfully.</jats:p>

Molecular and Biochemical Characterization of Jasmonic Acid Carboxyl Methyltransferase Involved in Aroma Compound Production of Methyl Jasmonate during Black Tea Processing

“…The processing procedures of black tea comprise withering (indoor withering or sun withering), rolling, fermentation, and drying. The unique aroma of black tea is formed during processing . It was reported that fresh tea leaves (Longjing 43) were processed into six tea types by the traditional processing methods, and the formation of tea aroma from these six model manufacturing processes was elucidated.…”

“…The unique aroma of black tea is formed during processing. 27 It was reported that fresh tea leaves (Longjing 43) were processed into six tea types by the traditional processing methods, and the formation of tea aroma from these six model manufacturing processes was elucidated. Feng et al indicated that the MeJA concentration was the highest in the black tea sample among the six tea types.…”

Application of Electronic Nose to Predict the Optimum Fermentation Time for Low-Country Sri Lankan Tea

“…Innovative technologies were developed by several research groups using the electronic eye method [5,11,[13][14][15][16][17][18], the electronic tongue method [19][20][21][22], and the electronic nose method [23][24][25][26][27][28][29][30][31][32][33][34][35] that aim at minimizing human intervention. At present, the electronic nose methods are often utilized to classify different types of tea or different tea grades [24,26,31,35].…”

Effect of brewing method on quality parameters and antioxidant capacity of black tea

“…Theaflavin and thearubigin increase a brewed tea's color, mouth-feel and body, and contribute to the briskness of the tea. These compounds are of such importance to the characteristic flavor and aroma of tea that methods of optimizing fermentation levels have been studied [3]. Feng et al (2019) investigated the effect of manufacturing processes on the aroma composition of tea leaves and reported that black tea has a concentration of 710 µg/g of volatile compounds whereas green tea has 20 µg/g [4].…”