Faith Nyamakwere¹,², Giulia Esposito¹,³, Kennedy Dzama¹, Pieter Gouws¹ , Teresa Rapisarda⁴, Giovanni Belvedere⁴, Felicia Masucci⁵ and Emiliano Raffrenato¹,*
1- Department of Animal Sciences, Stellenbosch University, Private Bag X1, Matieland 7602, South Africa; fnyamakwere@uneswa.sz (F.N.); giulia.esposito@unipr.it (G.E.); kdzama@sun.ac.za (K.D.); pgouws@sun.ac.za (P.G.)
2- Department of Animal Sciences, University of Eswatini, P.O. Box Luyengo, Luyengo H105, Eswatini
3- Department of Veterinary Science, University of Parma, 43121 Parma, Italy
4- Consorzio per la Ricerca nel Settore della Filiera Lattiero-Casearia e dell’Agroalimentare, 97100 Ragusa, Italy; rapisarda@corfilac.it (T.R.); belvedere@corfilac.it (G.B.)
5- Dipartimento di Agraria, Università degli Studi di Napoli Federico II, 80055 Portici, Italy; masucci@unina.it
* Correspondence: emiliano@sun.ac.za
ABSTRACT
The objective of this study was to evaluate the efficacy of gamma irradiation, applied to different cheese sample sizes (250g and 500 g), against Listeria monocytogenes, Escherichia coli, coliforms and aerobic colony counts. The effects on cheese physicochemical and odour properties and all costs involved for the treatment were quantified. The Cobalt-60 γ-irradiator was used at a maximum dose of 5.0 kGy. The values for cheese moisture (28.6%), ash (3.78%), pH (5.1), protein (29.6%), fat (30.7%), salt (1.95%) and water activity (0.92%) were within the acceptable ranges for hard cheese after gamma irradiation treatment. The colour (yellowness, redness, chroma and hue angle) and texture (cohesive- ness and springiness) values decreased (p < 0.05) with the treatment. Compounds such as safrole, acetylpyrazine, thiophene, 3,5-octadien-2-one and 1-Octen-3-one were present after the treatment, regardless of sample size. The gamma irradiation treatment resulted in 100%, 87.2%, 85.1% and 77.3% reduction in L. monocytogenes, coliforms, E. coli and aerobic colony counts, respectively. The study highlighted the efficacy of irradiation treatment and its affordability for resource-limited producers.
Keywords
cheese; irradiation cost; ionising radiation; microbial safety; Smart nose; gas chromatog- raphy olfactometry
Applied Science
2022, 12, 3142.
https://doi.org/10.3390/app 12063142
Faith Nyamakwere
