Ethyl formate

Methanol and acetonitrile (99% purity) were purchased from Aladdin Company (Shanghai, China). All standards used in this study, including lactic acid, propanoic acid, hexanoic acid, ethanol, Methanol, pentanol, n-propanol, ethyl lactate, ethyl acetate, and ethyl formate, were purchased from Sigma-Aldrich (St. Louis, MO, USA). All other chemicals and reagents used in this study were of analytical grade and were obtained from the Sinopharm Chemical Reagent Company (Beijing, China).

The initial population of moths used in the experiments was acquired originally from home storage of grain products in Daegu, Korea, in 2019, and brought into the laboratory. The colony of P. interpunctella was maintained at the insect physiology laboratory, Kyungpook National University, Daegu, Korea, where they were reared at 27 °C ± 1 °C, 70% ± 5% relative humidity, with a 16:8 h light:dark photoperiod, on an artificial diet consisting of a mixture of wheat bran (410 gm), pollen (780 gm), honey (80 mL), glycerin (80 mL), water (10 mL), and methyl paraben (1.17 gm). During their maintenance, P. interpunctella colony was not exposed to any insecticides.
The commercially available compounds MBe (99%), citronellal (95%), linalool (95%), 1,8 cineole (99%), limonene (97%), and ethyl formate (97%) were purchased from Sigma-Aldrich (St. Louis, MO, USA) (Figure 1).

Apples (Malus domestica ‘Jonathan’, Csány 1) were collected beside the city of Székesfehérvár, located in central Hungary, in September 2019, and were transported to the laboratory for subsequent analysis. The Jonathan apple is a classic American variety, medium-sized apple, and widely regarded as one of the best flavored, with a good sweet/sharp balance. The Viniflora Concerto^TM (L. thermotolerans) and Melody^TM (mixed culture of T. delbrueckii, L. thermotolerans, and S. cerevisiae) starter cultures were obtained from Chr. Hansen A/S (Hoersholm, Denmark), while the Biodiva^TM Level 2 (Torulaspora delbrueckii TD291) and Uvaferm 228 (S. cerevisiae) of Lallemand Inc. (Montréal, QC, Canada) dry yeasts were purchased from Kokoferm Ltd. (Gyöngyös, Hungary). Standards (glucose, fructose, saccharose, acetic acid, lactic acid, succinic acid, acetaldehyde, methanol, isoamyl alcohol, 1-propanol, 1-butanol, 2-butanol, 2-phenylethanol, 1-hexanol, 2-methyl-1-butanol, trans-3-hexen-1-ol, cis-2-hexen-1-ol, benzyl alcohol, ethyl acetate, propyl acetate, ethyl hexanoate, ethyl butyrate, isoamyl acetate, phenylethyl acetate, diethyl succinate, ethyl octanoate, ethyl benzoate, ethyl formate, linalool), and all chemicals of analytical grade were obtained from Sigma-Aldrich (Steinheim, Germany).

Unless otherwise stated, all materials were commercially available and used without further purification. All solvents were of analytical grade and used without further purification. 4-Aminobenzonitrile, trifluoromethanesulfonic acid (TFMSA) were purchased from Acros Organics. 1,4-Diacetylbenzene, potassium tert-butoxide and ethyl formate were purchased from Sigma–Aldrich.Co. Ltd. (TCI).