Effects of temperature fluctuations on the quality and characteristic volatile compounds of large yellow croaker (Pseudosciaena crocea) during cold chain logistics

Large yellow croaker (Larimichthys crocea) is one of economic important mariculture fish species with abundant nutritional value, and usually stored at refrigerated temperature. Our study investigated the effects of temperature fluctuation and abuse on the quality of the large yellow croaker and further analyzed the volatile compounds as temperature abuse sensitivity or indicators during temperature fluctuations. We simulated a cold chain model that mapped the temperature of chilled large yellow croaker during land-sea freight. Temperature fluctuation caused a non-negligible effect on the quality of the large yellow croaker. Samples exposed to greater temperature fluctuation had a higher rise in total viable count (TVC), total volatile basic nitrogen content, K value, and thiobarbituric acid reactive substances value. Among them, TVC is the sensitive index to temperature fluctuation. A total of 81 typical target compounds were identified by using headspace-gas chromatography-ion mobility spectrometry. During temperature fluctuations, the concentration of volatile aldehydes, including pentanal, heptanal, nonanal, and octanal decreased, while the concentration of ketones and nitrogenous and heterocyclic compounds increased. Principal component analysis and orthogonal partial least squares discriminant analysis showed that 2-pentanone and ethyl acetate were significantly correlated with the quality changes during temperature fluctuations, which could be the potential indicators for observing quality changes in large yellow croaker during temperature fluctuation.