## 3 Results and Discussion
### Volatile Profiles of Raw and Cooked Rice Samples  
The identified volatile compounds in raw and cooked rice samples are tabulated in Tables 1 and 2. Altogether, 18 and 22 volatiles were identified in the raw and cooked rice samples of varieties studied, respectively. The identification of these compounds was carried out based on mass spectra, retention index (RI) values, and authentic standards (Tables 1 and 2). The relative concentration of the identified volatile compounds in raw and cooked rice samples among studied varieties are also depicted in Tables 1 and 2. The volatile compounds, 1-hexanol, and ethyl 3-hydroxybutyrate, were common in the raw rice samples of all varieties studied. The aliphatic aldehydes and alcohols, such as 1-hexanol and nonanal, are lipid oxidation products and were reported to be responsible for aroma intensities of aromatic and non-aromatic rice [23; 24]. The content 2-ethyl-1-hexanol was highest in the raw rice samples of most of the varieties, except IR-64 and Govind Bhog. Interestingly, 2-ethyl-1-hexanol was not detected in the cooked rice samples, which showed that it can be lost in the cooking process and can be a volatile marker compound for freshly milled rice samples. The 2-ethyl-1-hexanol is the contributor for citrus, fresh floral, oily, and sweet aromas, and is identified as a discriminating compound for Basmati brand B, and a maker for rice aging in certain varieties in previous studies [25; 26]. \begin{table}
\begin{tabular}{l c c c c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Component**} & \multirow{2}{*}{**RI\({}_{\text{tot}}\)**} & \multirow{2}{*}{**RI\({}_{\text{tot}}\)**} & \multirow{2}{*}{  
The raw rice samples of Pusa-1652 (Improved Kala Namak) had almost all identified volatile compounds in detectable amounts, except ethyl hexanoate and 1,3-Butanediol. The raw rice of Pusa-1652 (Improved Kala Namak) depicted significantly higher 2-AP, phenylethyl alcohol, and indole contents compared with raw rice samples of other varieties. The contents of nonanoic acid, ethyl ester, 2,3-butanediol, 1-octanol, tetradecanoic acid, ethyl ester, and ethyl 9-hexadecenoate were significantly higher in the raw rice samples of Pusa Basmati-1509. The raw rice samples of the traditional variety, Kala Namak-2, had the highest content of 2-AP after Pusa-1652 (improved Kala Namak). Both Pusa-1652 (Improved Kala Namak) and Kala Namak-2 had a significantly higher amount of 1-octen-3-ol. The 1-octen-3-ol is an off-flavor-causing component responsible for green, mushroom, earthy, and oily aromas, which was reduced or lost after cooking in these varieties [27]. The content of certain volatile compounds was found to be increased after cooking, but this increase was rice-genotype-specific (Table 2). Interestingly, the volatile compounds such as ethyl butyrate, ethyl 3-methylbutanoate, 2-undecanone, ethyl benzoate, ethyl benzeneacetate, 2-methylnaphthalene, and 1-methylnaphthalene were characteristically detected in the cooked rice samples. This finding demonstrated that these volatile compounds were either released or formed during cooking. Both ethyl butyrate and ethyl 3-methylbutanoate were detected together in Pusa-1652 (Improved Kala Namak), and Kala Namak-2 cooked rice samples. The highest amount of 2-AP was found in Pusa-1652 (Improved Kala Namak), followed by Kala Namak-2, Govind Bhog, and Kala Jeera. Cooked rice of Pusa Basmati-1, Pusa Basmati-1509, and Jeera-32 had an almost similar amount of 2-AP. Nonanal content was highest in the cooked rice samples of Pusa Basmati-1509. Notably, 1-octanol was observed in cooked rice samples of all varieties, except Pusa-1652 (Improved Kala Namak). An increase in indole content was observed in the cooked rice samples of IR-64 and Kala Namak-2. Conversely, it decreased to an undetectable level after cooking in Pusa-1652 (Improved Kala Namak).