Flavour in legumes is highly subjective but it is fair to say that most of the volatile compounds in peas (Pisum sativum) as in any legume results from fatty acid decomposition caused by enzymatic and non-enzymatic reactions during storage.
By the way, peas, out of all the legumes are probably the most widely studied because they appear to be the most susceptible to flavour deterioration. Whilst the majority of compounds to be found are common to all legumes, there are a few which appear specific to peas such as the 3-alkylmethoxypyrazines which are contributors to beany off-notes. About 4 are known. Its probable to be too precise as some others at minute but sensorially critical levels are likely to be detected in due course. One recent compound, 5- or 6-methyl-3-isopropyl-2-methoxypyrazine has been identified.
Dynamic headspace techniques have been employed to assess the volatiles coming from peas during harvesting and then blanching or canning. At least 47 compounds were detected as aroma compounds in peas being blanched (Jakobsen et al., 1998). All of them are largely degradation products of fatty acids, especially saturated and monounsaturated six-carbon aldehydes, ketones, alcohols, and their ester derivatives.
Pea flavour, especially the concentration of various compounds depends on the genotype of the pea. Specific cultivars such as Kelvedon Wonder and The Ambassador are claimed to be excellent varieties for fresh pea flavour. We have discussed the cultivation of peas for home use for example elsewhere on this web-site.
Preservation of pea flavour is an essential if the unpleasant beany notes are not to occur. It is thought that varieties with a high antioxidant content offer better protection by reducing the formation of lipid hydroperoxides which ultimately produce off-notes. Ascorbic acid (vitamin C) appears to be the main antioxidant and depends not only on the cultivar but growing conditions and environment (Nilsson et al., 2004).
A sophisticated analytical techniques using headspace-solid phase microextraction gas chromatography–mass spectrometry has been tried in assessing the volatile flavour profile of various peas during processing. There was a significant reduction in volatile compounds following cooking and with dehulling, Removal of the skins has the most significant impact (Azarnia et al., 2011).
Azarnia, S., Boye, J. I., Warkentin, T., Malcolmson, L., Sabik, H., & Bellido, A. S. (2011). Volatile flavour profile changes in selected field pea cultivars as affected by crop year and processing. Food Chemistry, 124(1), pp. 326-335.
Jakobsen, H. B., Hansen, M., Christensen, M. R., Brockhoff, P. B., & Olsen, C. E. (1998). Aroma volatiles of blanched green peas (Pisum sativum L.). Journal of Agricultural and Food Chemistry, 46(9), 3727-3734 https://pubs.acs.org/doi/abs/10.1021/jf980026y
Nilsson, J., Stegmark, R., & Åkesson, B. (2004). Total antioxidant capacity in different pea (Pisum sativum) varieties after blanching and freezing. Food Chemistry, 86(4), pp. 501-507 https://doi.org/10.1016/j.foodchem.2003.09.002
Pattee, H.E., Salunkhe, D.K., Sathe, S.K. & Reddy, N.R. (1982). Legume lipids. Critical Reviews in Food Science and Nutrition, 17, pp. 97–139. https://doi.org/10.1080/10408398209527345