magistrsko delo
Eva Miljevič (Author), Tomaž Požrl (Reviewer), Sonja Smole Možina (Mentor), Michael Stelzl (Co-mentor)

Abstract

Bakterije rodu Campylobacter so vodilni povzročitelji bakterijskega gastroenteritisa pri ljudeh. Prenosi s hrano, predvsem preko kontaminirane perutnine, so glavni vzrok za humano kampilobakteriozo. Ker dekontaminacija trupov perutnine in mesa lahko pripomoreta k zmanjšanju pojavnosti bakterijskih okužb s hrano pri ljudeh, smo v eksperimentalnem delu najprej testirali občutljivost sevov C. coli in C. jejuni (N=17) na izpostavljenost aerobnim razmeram, da bi ugotovili, ali je med sevi razlika v odpornosti na atmosfersko koncentracijo kisika. V nadaljevanju smo testirali občutljivost sevov na povečano koncentracijo kisika v modificirani atmosferi s 70 % O2 ter 30 % CO2 in opazovali preživetje sevov po tretiranju z 10 % raztopino mlečne kisline (MK) in 0,5 % ter 1 % raztopino perocetne kisline (PAA). Glede na občutljivost na kisik smo seve razdelili na aerosenzitivne (AS) (preživeli <24 h v aerobnih razmerah) in hiperaerotolerantne (HAT) (preživeli >24 h v aerobnih razmerah). Skupno je 65 % testiranih sevov C. coli in C. jejuni pripadalo skupini AS, ter 35 % HAT. Pakiranje v modificirano atmosfero (MAP) je v povprečju zmanjšalo število AS kampilobaktrov za 1,96 log CFU/ml, ter HAT za 0,89 log CFU/ml. Izmed kislin je bila učinkovitejša PAA. V 0,5 % raztopini je v povprečju zmanjšala število bakterij AS sevov za >3,85 log CFU/ml in pod mejo zaznavnosti zmanjšala število bakterij 3 aerosenzitivnih sevov. Število bakterij HAT sevov je povprečno zmanjšala za 3,62 log CFU/ml. 1 % raztopina PAA je pod mejo zaznavnosti zmanjšala število bakterij 5 AS sevov ter 1 HAT seva, ter v povprečju zreducirala število bakterij AS sevov za >4,57 log CFU/ml in HAT sevov za >4,68 log CFU/ml. MK je v 10 % koncentraciji v povprečju zmanjšala število HAT in AS sevov za 1,58 log CFU/ml in 1,25 log CFU/ml. Aerotolerantni sevi C. coli in C. jejuni so zelo razširjeni v perutnini in povečajo možnost za prenos bakterij preko hrane v aerobnih razmerah. Ustrezna uporaba MK in PAA ter MAP so učinkovite metode za zmanjšanje števila kampilobaktrov, ki lahko izboljšajo varnost živil.

Keywords

Campylobacter jejuni;Campylobacter coli;in vitro;piščančje meso;odpornost na kisik;pakiranje v modificirano atmosfero;mlečna kislina;perocetna kislina;hiperaerotolerantni sevi;

Data

Language: Slovenian
Year of publishing:
Typology: 2.09 - Master's Thesis
Organization: UL BF - Biotechnical Faculty
Publisher: [E. Miljevič]
UDC: 579.67:637.54.033:621.798
COBISS: 79460355 Link will open in a new window
Views: 207
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Other data

Secondary language: English
Secondary title: In vitro screening of the efficiency procedures for Campylobacter reduction in the chicken meat production chain
Secondary abstract: Campylobacter spp. are the leading cause of bacterial gastroenteritis in humans. Transmission via contaminated poultry is a major cause of human Campylobacteriosis. Decontamination of poultry meat can reduce the incidence of foodborne infections, so we tested the susceptibility of C. coli and C. jejuni (N=17) strains to aerobic exposure to determine the difference in resistance of strains exposed to atmospheric oxygen concentration. Furtheron, we tested the sensitivity of the strains to the increased oxygen concentration in a modified atmosphere with 70 % O2 and 30 % CO2 and after treatment with 10 % lactic acid solution (MK) and 0,5 % and 1 % peracetic acid solution (PAA). According to oxygen sensitivity, strains were aerosensitive (AS) (survived <24 h under aerobic conditions) and hyperaerotolerant (HAT) (survived >24 h under aerobic conditions). In total, 65 % of the tested strains of C. coli and C. jejuni belonged to the AS group, and 35 % to the HAT. Modified atmosphere packaging (MAP) reduced the average number of AS strains by 1,96 log CFU/ml, and HAT by 0,89 log CFU/ml. Of the acids, PAA was more effective. In a 0,5 % PAA solution, the average number of AS strains was reduced by >3,85 log CFU/ml and 3 aerosensitive strains below the detection limit. The number of HAT strains decreased on average by 3,62 log CFU/ ml. 1 % PAA solution reduced the number of 5 AS strains and 1 HAT strain below the detection limit, and on average reduced the number of bacteria of AS strains by >4,57 log CFU/ml and HAT strains by >4,68 log CFU/ml. A 10 % solution of MK reduced the average number of HAT and AS strains by 1,58 log CFU/ml and 1,25 log CFU/ml. Aerotolerant strains of C. coli and C. jejuni are widespread in poultry and increase the potential for bacterial transmission through food under aerobic conditions. Proper use of MK and PAA and MAP are effective methods to reduce the number of Campylobacter and can improve food safety of poultry meat.
Secondary keywords: Campylobacter jejuni;Campylobacter coli;in vitro;chicken meat;tolerance to oxygen;modified atmosphere packaging;lactic acid;peperacetic acid;hyperaerotolerant strains;
Type (COBISS): Master's thesis/paper
Study programme: 0
Thesis comment: Univ. v Ljubljani, Biotehniška fak., Oddelek za živilstvo
Pages: XI, 64 f., [2] f. pril.
ID: 13646715