Reduction of the microbial load of the Pacific white shrimp Litopenaeus vannamei (Boone, 1931) grown in a biofloc system, using different sanitizing treatments
Author: Antenor Turchetto Neto (Currículo Lattes)
Supervisor: Dr Carlos Prentice Hernández
Co-supervisor: Dr Wilson Francisco Britto Wasielesky Junior
Abstract
The fish in general, presents physiological and biochemical aspects that provide intrinsic conditions favorable to accelerated degradation, during the stage of harvesting, and storage, the shrimp needs to receive appropriate treatments in order to maintain the conditions suitable for human consumption. Sanitization aims to reduce the initial microbial load and eliminate pathogens. Chlorine-based compounds are the most used for this purpose in the commercial and industrial spheres, however, due to controversies about their toxicity, other sanitizers have increasingly aroused the interest of the food sector. The aim of this study was to compare the efficiency of different sanitizers such as chlorine, acetic acid and sodium metabisulfite, on the white shrimp microbiota,(Litopenaeus vannamei) grown in a biofloc system (BFT), in order to evaluate the influence of the microbial community on the biofloc present in white shrimp. The sensory attributes are extremely relevant to estimate freshness, therefore the crustacean samples were subjected to analysis of chemical proximal composition, tests of total volatile bases (BVT), substances reactive to thiobarbituric acid (TBARs), pH, microbiological analyzes (counts total mesophiles and psychrotrophic) and histamine determination. These tests, analyzed together, are considered adequate parameters of the quality of the fish. The samples analyzed by the chemical characterization of white shrimp, characterized it as a matrix of high nutritional value and product acceptability had attributes close to the ideal.Shrimp from BFT cultivation were used. At slaughter, sanitizing treatments were performed in two concentrations, after which they were stored in isothermal boxes with ice for 20 days. For mean pH values of 7.2 to 8.2 after storage on ice for 20 days, BVT between 14.39 to 22.23 mgN/100 g in the initial analysis and exceeding the deterioration limit in the final collection 43, 45 to 121.48 mgN/100 g, after storage. TBARs from 0.37 to 0.61 mg malonic aldehyde/kg in the initial analysis, initial mesophilic count from 3.4X103 to 2.40X104 UFC/g in the control treatment and initial psychrotrophic count ranging from 1.25X101 to 4.00X102 CFU/g in the control treatment. The presence of histamine was detected from the 10th day, with values below the recommended limits, being 0.17 to 0.20mg/100g.The results obtained suggest chemical and microbiological quality are satisfactory for the analyzed white shrimp samples, compatible for a product considered commercially fresh.