Aflatoksiinide mõju juustus esinevatele piimhappebakteritele
Laen...
Kuupäev
2021
Kättesaadav alates
04.09.2021
Autorid
Ajakirja pealkiri
Ajakirja ISSN
Köite pealkiri
Kirjastaja
Eesti Maaülikool
Abstrakt
Juust on levinud piimatoode kogu maailmas. Sobilike niiskuse ning temperatuuri
parameetrite tõttu, on juust hallitusseente arenemiseks hea keskkond. Mõned
hallitusseente hulka kuuluvad Aspergillus perekonna liigid toodavad aflatoksiini, mis
omab kantserogeenseid, mutageenseid ja immunosupressiivseid omadusi ning mida on
1990. aastal ilmunud teadusartiklis seostatud juustude hilise paisumisega, olles seni
teadaolevalt ainus teadustöö, mis sellist seost kajastab. Kuna juustude paisumine on
piimatööstuste jaoks probleemiks ka tänapäeval, väärib antud teema laialdasemat
uurimist.
Bakalaureusetöö eesmärk on nii teaduskirjanduse kui eksperimentaalse töö alusel anda
ülevaade aflatoksiinidest ja aflatoksiin B1 poolt avaldatavast mõjust juustus esinevatele
piimhappebakteritele.
Töö raames teostati katsed hilise paisumisega juustudes sisalduvate mikroobide
isoleerimiseks, säilitamiseks ja arvukuse määramiseks ning hinnati erineva
kontsentratsiooniga aflatoksiini mõju piimhappebakterite referentstüvedele ning
juustudest isoleeritud kultuuridele. Leiti, et uuritud juustude mikrobioloogiliste analüüside
tulemused olid üksteisega sarnased ning ei selgitanud hilise paisumise põhjuseid.
Aflatoksiini poolt avaldatav mõju esines vaid ühest juustust isoleeritud fakultatiivselt
heterofermentatiivse Lactobacillus paracasei puhul, kus nii glükoosi kui galaktoosi
kasvusöötmega katsutites ilmnes 5. inkubatsioonipäevaks gaasi tootmine aflatoksiin B1
kontsentratsioonil 10-40 µg/ml. Nimetatud süsivesikutega kasvusöötmete puhul täheldati
ka aflatoksiini pärssivat toimet L. paracasei happe tootlikkusele juba toksiini madalatel
kontsentratsioonidel vastavalt 10 ja 1 µg/ml.
Kokkuvõtteks võib öelda, et ehkki töö ei kinnitanud aflatoksiin B1 mõju
homofermentatiivsete piimhappebakterite süsivesikute fermentatsiooniprotsessile ja selle
seost juustude hilise paisumisega, väärib teema edasist uurimist suurema hulga juustude
isolaatide ja starterkultuuridega, seahulgas piimatööstuse keskkonnas esinevate
fakultatiivselt heterofermentatiivsete piimhappebakteritega.
Cheese is a popular dairy product all over the world. Due to its suitable humidity and temperature parameters, cheese also constitutes a good environment for the development of molds. Some species of the genus Aspergillus produce aflatoxin, which has carcinogenic, mutagenic and immunosuppressive properties. Aflatoxin has been linked to the late blowing of cheeses in a scientific article published in 1990, being the only research known to date that reflects such correlation. As the blowing of cheeses is still a problem for the dairy industry today, this topic deserves further investigation. The aim of the Bachelor's thesis is to provide an overview of aflatoxins in general and the effect of aflatoxin B1 on homofermentative lactic acid bacteria found in cheese, based on scientific literature and experimental work in particular. During this research experiments were performed to isolate, preserve and quantify the microbes contained in late-blown cheeses, and to evaluate the effects of different concentrations of aflatoxin on reference strains of lactic acid bacteria and on cultures isolated from cheeses. The results of the microbiological analyses of the two cheeses examined were found to be similar to each-other and did not explain the late blowing. The effect of aflatoxin was only observed on the facultatively heterofermentative Lactobacillus paracasei isolated from cheese, where both glucose and galactose growth medium tubes showed gas production by day 5 of incubation, at aflatoxin B1 concentrations of 10-40 µg/ml. Inhibitory effects of aflatoxin on L. paracasei acid production were also observed for these carbohydrate growth mediums even at low toxin concentrations of 10 and 1 µg/ml respectively. In conclusion, although our research did not confirm the effect of aflatoxin B1 on the carbohydrate fermentation process of homofermentative lactic acid bacteria and its involvement in the late blowing of the cheeses, the issue deserves further investigation with a wider range of cheese isolates and starter cultures, including facultatively heterofermentative lactic acid bacteria that are present in the dairy industry.
Cheese is a popular dairy product all over the world. Due to its suitable humidity and temperature parameters, cheese also constitutes a good environment for the development of molds. Some species of the genus Aspergillus produce aflatoxin, which has carcinogenic, mutagenic and immunosuppressive properties. Aflatoxin has been linked to the late blowing of cheeses in a scientific article published in 1990, being the only research known to date that reflects such correlation. As the blowing of cheeses is still a problem for the dairy industry today, this topic deserves further investigation. The aim of the Bachelor's thesis is to provide an overview of aflatoxins in general and the effect of aflatoxin B1 on homofermentative lactic acid bacteria found in cheese, based on scientific literature and experimental work in particular. During this research experiments were performed to isolate, preserve and quantify the microbes contained in late-blown cheeses, and to evaluate the effects of different concentrations of aflatoxin on reference strains of lactic acid bacteria and on cultures isolated from cheeses. The results of the microbiological analyses of the two cheeses examined were found to be similar to each-other and did not explain the late blowing. The effect of aflatoxin was only observed on the facultatively heterofermentative Lactobacillus paracasei isolated from cheese, where both glucose and galactose growth medium tubes showed gas production by day 5 of incubation, at aflatoxin B1 concentrations of 10-40 µg/ml. Inhibitory effects of aflatoxin on L. paracasei acid production were also observed for these carbohydrate growth mediums even at low toxin concentrations of 10 and 1 µg/ml respectively. In conclusion, although our research did not confirm the effect of aflatoxin B1 on the carbohydrate fermentation process of homofermentative lactic acid bacteria and its involvement in the late blowing of the cheeses, the issue deserves further investigation with a wider range of cheese isolates and starter cultures, including facultatively heterofermentative lactic acid bacteria that are present in the dairy industry.
Kirjeldus
Bakalaureusetöö
Toiduainete tehnoloogia õppekaval
Märksõnad
bakalaureusetööd, juust, aflatoksiinid, piimhappebakterid, paisumine