title: Shelf Life Evaluation ofRicotta FrescaSheep Cheese in Modified Atmosphere Packaging.
abstract: Ricotta frescacheese is the product of Sardinian dairy industry most exposed to microbial post-process contamination. Due to its technological characteristics, intrinsic parameters, pH (6.10-6.80) and water activity (0.974-0.991), it represents an excellent substrate for the growth of spoilage and pathogenic microorganisms, which are usually resident in cheese-making plants environments. Generally,ricotta frescahas a shelf life of 5-7 days. For this reason, at industrial level, modified atmosphere packaging (MAP) is used to extend the durability of the product. However, few investigations have been conducted to validate the use of MAP inricotta fresca.The aim of this work is to evaluate the shelf life ofricotta frescaunder MAP. A total of 108 samples were collected from three Sardinian industrial cheese-making plants and analysed within 24 h after packaging and after 7, 14 and 21 days of refrigerated storage. Aerobic mesophilic bacteria, mesophilic and thermophilic cocci and lactobacilli,EnterobacteriaceaeandE. coli, L. monocytogenes, Pseudomonasspp,Bacillus cereus, yeasts and moulds, and the chemical-physical parameters and composition of the product were determined. At the end of the shelf life,Pseudomonasspp. andEnterobacteriaceaereached high concentrations, 5 to 7 and 3 to 6 log10colony forming unit g-1, respectively. The presence of environmental contaminants indicates that the use of MAP without the appropriate implementation of prerequisite programmes is not sufficient to extend the durability ofricotta fresca.Gas mixture and packaging material should be selected only on the basis of scientific evidence of their effectiveness.
authors.affiliation: Department of Veterinary Medicine, University of Sassari , Sassari, Italy.
authors.forename: Carlo
authors.initials: C
authors.lastname: Pala
authors.affiliation: Department of Veterinary Medicine, University of Sassari , Sassari, Italy.
authors.forename: Christian
authors.initials: C
authors.lastname: Scarano
authors.affiliation: LAORE Sardinia Agency , Zootechnical Production Department, Sassari, Italy.
authors.forename: Massimiliano
authors.initials: M
authors.lastname: Venusti
authors.affiliation: LAORE Sardinia Agency , Zootechnical Production Department, Sassari, Italy.
authors.forename: Daniela
authors.initials: D
authors.lastname: Sardo
authors.affiliation: Department of Veterinary Medicine, University of Sassari , Sassari, Italy.
authors.forename: Daniele
authors.initials: D
authors.lastname: Casti
authors.affiliation: Department of Veterinary Medicine, University of Sassari , Sassari, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Cossu
authors.affiliation: Department of Veterinary Medicine, University of Sassari , Sassari, Italy.
authors.forename: Sonia
authors.initials: S
authors.lastname: Lamon
authors.affiliation: Department of Veterinary Medicine, University of Sassari , Sassari, Italy.
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Spanu
authors.affiliation: Department of Veterinary Medicine, University of Sassari , Sassari, Italy.
authors.forename: Michela
authors.initials: M
authors.lastname: Ibba
authors.affiliation: Department of Veterinary Medicine, University of Sassari , Sassari, Italy.
authors.forename: Michela
authors.initials: M
authors.lastname: Marras
authors.affiliation: AGRIS Sardinia Agency , Department of Research on Animal Production, Sassari, Italy.
authors.forename: Antonio
authors.initials: A
authors.lastname: Paba
authors.affiliation: Department of Veterinary Medicine, University of Sassari , Sassari, Italy.
authors.forename: Carlo
authors.initials: C
authors.lastname: Spanu
authors.affiliation: Department of Veterinary Medicine, University of Sassari , Sassari, Italy.
authors.forename: Enrico Pietro Luigi
authors.initials: EP
authors.lastname: De Santis
keywords: MAP; Ricotta cheese; Sheep milk; Whey cheese