Quality Index Method (QIM) for Gutted Ice-stored piauçu (Leporinus macrocephalus) and Determination of Shelf Life

The Quality Index Method can be applied to different fish species with the main advantage of quantifying the freshness level of the fish without destroying a sample. The freshness level is decisive for the commercial shelf life of fish, therefore this study aimed to develop a Quality Index Method for gutted piauçu (Leporinus macrocephalus) stored in ice and estimate its shelf life according to sensory, physical-chemical and microbiological characteristics. Nine trained evaluators evaluated the gutted fish during 18 days of storage, using the Quality Index Method protocol. The samples were also characterized for mesophilic bacteria, psychrotrophic bacteria, hydrogenionic potential, total volatile bases and thiobarbituric acid reactive substances. Partial least squares regression was used to correlate the QIM attributes, and linear regression analysis was used to verify the variables as a function of storage time. The Quality Index Method scheme was developed based on 19 merit points, where zero indicates total freshness. The coefficient of determination for the linear regression between QI and storage time in ice was R2=0.78. Microbiological count results ranged from 4.43 to 15.59 log CFU/g for mesophilic bacteria and from 1.76 to 12.08 log CFU/g for psychrotrophic bacteria during ice storage. The results of the hydrogenionic potential, total volatile bases and thiobarbituric acid reactive substances ranged from 6.32 to 6.96; 10.57 to 13.30 mg N/100g; and 0.35 to 0.88 mg of malondialdehyde/kg, respectively. The integration of sensory, microbiological and physicochemical data allowed the shelf life of eviscerated piauçu stored on ice to be estimated at eight days.