*3.4. Active Odorants*

Based on quantitation, the calculation of odor activity values (OAVs) enables a more reliable evaluation of important odorants in foods [42]. Volatile compounds are considered to contribute to the overall flavor of the tomato when their concentration is greater than detection thresholds [43]. As shown in Table 2, a total of 19 aroma compounds, with

their OAVs > 1, were selected. cis-3-Hexenal was the most active compound, which presented "green", "leafy" notes (Table 2). As shown in the Figure 6, tomatoes mainly emitted the aroma of "green" and "leafy", confirming that the fatty acid pathway was the important biosynthesis pathway of aroma for "Tasti-Lee" tomatoes. Tomatoes harvested at the mature green stage displayed the strongest "green" and "leafy" notes, as is consistent with many tomato flavor research reports [5,8]. 2-Methylbutanal and 3-methylbutanal were also major contributors to the aroma, which are the derivatives of amino acids and were described as "malt" notes (Table 2) [36]. The aroma of "malt" plays an important part in tomato flavor (Figure 6) [36]. After chilling or blanching treatment, the flavor of tomatoes generally decreased depending on harvest maturity and temperature treatment combinations (Figure 6). Fruit harvested at the turning stage had the second most abundant volatiles after ripening, only less than that in the mature green harvested fruit, and had very limited odor-active volatile loss after chilling and blanching treatments (Table 2, Figure 6).

**Figure 6.** Effects of different treatment combinations of harvest maturity and temperature on aromatic volatiles by reported flavor sensory property (see Table 2). Abbreviations represent combinations of harvest maturity (R—red; L—light red; P—pink; T—turning; B—breaker; and M—mature green) and temperature treatment (h—heating; c—chilling; n—non-treated control).

*Foods* **2021**, *10*, 1727

**Table 2.** Odor activity values (OAVs) of active volatile compounds determined in the different treated tomatoes harvested at six maturity stages and treated by refrigeration (chilling, c), blanching(heating,h),ornon-treated(control,n).


z: Odor description of 6-methyl-5-hepten-2-one adapted from Klee [36], while others from Acree and Arn [44]. y: Odor threshold values (detection) in water adapted from Van Gemert [45]. When there was more than one value, those from the USDA, ARS laboratory in Albany (CA) were chosen for consistency of the methodology. x: Abbreviations of combination of harvest maturity (R—red; L—light red; P—pink; T—turning;B—breaker;andM—maturegreen)andtemperaturetreatment(h—heating;c—chilling;n—non-treatedcontrol).
