Table 3.
Volatile compounds (area units/10,000) identified in Parmigiano Reggiano cheeses ripened from 12 to 50 months.
| Compound | LRI a | Identification b | Ripening Time (Months) | |||||
|---|---|---|---|---|---|---|---|---|
| 12 | 18 | 24 | 30 | 40 | 50 | |||
| Acids | ||||||||
| Acetic acid | 1455 | MS, PI | 1000 ± 200 | 850 ± 270 | 950 ± 60 | 1300 ± 120 | 1100 ± 110 | 1200 ± 90 |
| Propanoic acid | 1546 | MS, PI | 3 ± 0 | 24 ± 2 | 4 ± 2 | 7 ± 1 | 8 ± 1 | 6 ± 1 |
| Butanoic acid | 1640 | MS, PI | 4300 ± 300 | 4500 ± 700 | 5500 ± 300 | 8100 ± 500 | 9300 ± 400 | 11000 ± 890 |
| Pentanoic acid | 1755 | MS, PI | 18 ± 1 | 21 ± 4 | 41 ± 14 | 73 ± 8 | 97 ± 9 | 91 ± 7 |
| Hexanoic acid | 1870 | MS, PI | 4800 ± 900 | 5600 ± 760 | 7000 ± 700 | 12000 ± 1200 | 12000 ± 890 | 17000 ± 1300 |
| Heptanoic acid | 1957 | MS, PI | ND | 6 ± 3 | 28 ± 21 | 74 ± 50 | 23 ± 15 | 58 ± 23 |
| Octanoic acid | 2066 | MS, PI | ND | 71 ± 10 | 170 ± 60 | 1300 ± 1200 | 500 ± 67 | 1700 ± 500 |
| 2-Methylbutanoic acid | T | 4 ± 0.3 | 4 ± 0.3 | 3 ± 0.5 | 2 ± 0.4 | 3 ± 0.2 | 3 ± 0.2 | |
| 3-Methylbutanoic acid | T | 40 ± 0.3 | 36 ± 5 | 16 ± 5 | 20 ± 3 | 6 ± 1 | 20 ± 3 | |
| Sum of areas | 10165 | 11112 | 13712 | 22876 | 23037 | 31078 | ||
| Ketones | ||||||||
| 2-Pentanone | 990 | MS, PI, ST | 150 ± 12 | 400 ± 90 | 400 ± 110 | 300 ± 70 | 300 ± 50 | 340 ± 50 |
| 2-Heptanone | 1190 | MS, PI, ST | 200 ± 40 | 570 ± 180 | 700 ± 40 | 600 ± 130 | 600 ± 70 | 630 ± 120 |
| 2-Nonanone | 1400 | MS, PI, ST | 80 ± 2 | 170 ± 40 | 400 ± 100 | 290 ± 100 | 270 ± 60 | 700 ± 200 |
| 8-Nonen-2-one | 1495 | MS, PI | ND | 15 ± 2 | 30 ± 15 | 40 ± 4 | 20 ± 4 | 70 ± 21 |
| Sum of areas | 430 | 1155 | 1530 | 1230 | 1190 | 1740 | ||
| Alcohols | ||||||||
| 2-Pentanol | 1172 | MS, PI, ST | 95 ± 8 | 97 ± 76 | 86 ± 83 | 45 ± 8 | 18 ± 4 | 48 ± 18 |
| 2-Heptanol | 1320 | MS, PI | 45 ± 4 | 33 ± 23 | 38 ± 23 | 17 ± 2 | 17 ± 4 | 37 ± 17 |
| Sum of areas | 140 | 130 | 124 | 62 | 35 | 85 | ||
| Esters | ||||||||
| Ethyl butanoate | 1055 | MS, PI | 250 ± 1 | 440 ± 49 | 150 ± 14 | 580 ± 96 | 330 ± 96 | 500 ± 87 |
| Ethyl hexanoate | 1240 | MS, PI | 430 ± 54 | 1000 ± 170 | 230 ± 70 | 2000 ± 75 | 720 ± 132 | 1300 ± 170 |
| Ethyl octanoate | 1440 | MS, PI | 35 ± 2 | 98 ± 8 | 11 ± 4 | 287 ± 35 | 81 ± 17 | 249 ± 30 |
| Sum of areas | 715 | 1538 | 391 | 2867 | 1131 | 2049 | ||
| Total sum of areas | 11450 | 13935 | 15757 | 27035 | 25393 | 34952 | ||
Data are expressed as the mean ± standard deviation. a Linear Retention Index in cheese samples using a StabilWax Column. b Identification method: MS = identification by spectra comparison in NIST Library; PI = comparison with published LRI; T = tentatively identified; ST = standard injection.