The effects of CP content on the shelf life were highly significant, with a greater coefficient of determination (R2 = 0.774) for B grade shelf life than NFE (0.437) (Tables 4 and S4; Fig. 3). The mineral CaO content significantly affected on shelf life as well. This indicates that the nitrogen source and CaO were plausible elements for determining shelf life. Interestingly, high correlation was found between Cao and CP and it was expected by that the content of CaO in the nitrogen sources (CP ≥ 10%) was linear relationship with that of T–N (r = 0.96, Table S2). Although calcium chloride has been widely used to improve shelf life of vegetables including mushrooms with proven effects ( Philippoussis et al., 2001a and Martin-Diana et al., 2007) and a correlation between CP and CaO was high, it seems improbable that CaO was sole main element responsible for shelf life. CP showed a higher R2 with B grade shelf life compared with CaO, and furthermore, A grade shelf life was significantly extended with increased the contents of lysine, glutamic acid and leucine in media (Table S4). It seemed possible that two elements presented synergistic effects on shelf life because the value CP × CaO showed statistically higher correlation with shelf life (R2 = 0.728–0.819, P < 0.05) than that of CaO or CP