Evaluation of potential use of cheese whey fermented extracts in food safety
M.I.S. Santos1,3,4, C.M.B.S. Pintado 1,2,5, S.R.C. Martins1, A.C.S. Cação1,4, L. Pedroso4, I. Sousa1 and
M.A.S.S.Ferreira 1*
1
Microbiology Laboratory, CBAA, DRAT and Eco-processing of Food and Feed, CEER, DCEB, Agronomics School,
Technical University of Lisbon, 1349-017 Lisbon, Portugal. *[email protected]
2
Escola Superior Agrária (ESA), IPCB, Quinta da Senhora de Mércules, Apartado 119, 6001-909 Castelo Branco, Portugal.
3
Universidade Lusófona de Humanidades e Tecnologias, Campo Grande, 376, 1749-024 Lisboa, Portugal.
4
Center for Research and Training in Food Quality and Safety, Higher Institute of Health Sciences Egas Moniz, Campus
Universitário, Quinta da Granja, 2829 - 511Almada, Portugal.
5
CERNAS, Centro de Estudos de Recursos Naturais, Ambiente e Sociedade, ESACB, Portugal.
Increasing attention has been given to physiological active peptides obtained by fermentation of milk proteins
with proteolytic starter bacteria. Peptides and organic acids obtained by Lactic Acid Bacteria fermentations,
proved to have bioactivity against pathogenic bacteria. Nisin is one of such peptides, which belongs to class I
bacteriocins and is produced by Lactococcus lactis, which has food safe status recognized by the Food and Drug
Administration. A high susceptibility (50 IUmL-1) to this small peptide was found in 219 Listeria spp. wild-type
strains isolated from ewes’ milk, cheese and cheese processing environment, when compared to strains from
other origins. Spontaneous resistance, at a frequency of 10-3 to 10-4 was observed, under confined conditions of
pH and temperature, showing enormous application possibilities. Recognition of new bioactive peptides,
naturally formed in fermented dairy products, driven us to compare six cheese wheys, inoculated with a mixture
of industrial starters. Selected fermentation extracts, were evaluated to determine, i) their lactic acid yield, ii)
their bioactivity against reference microorganisms and iii) to further characterize the bio potential of peptides
formed. A yield of 26±1 g.L-1 of lactic acid was achieved from a concentration of 30±2 g.L-1 of lactose and
sanitation of organic lettuce with this extract gave a reduction of 1.45 log cfu.g-1 in mesophilic counts and of 2.01
log cfu.g-1 in Enterobacteriaceae, increasing safety and shelf life of the product. A good bioactivity was shown
by the peptides formed, when determined on well diffusion agar plates.
New trends in food safety and preservation, advise the use of natural products, due to increase in human
sensitivity to traditional chemical preservatives. The utmost output of this work is to produce safer RTE
vegetable products, “supplemented” with milk bioactive peptides, whose health benefits has a growing interest,
well documented in clinical studies referred in the literature.
Keywords: Nisin; bioactive milk peptides; Listeria spp.; cheese whey, RTE vegetables.