Study On Influencing Factors Of Biogenic Amines In Cheese

The influencing factors and mechanism of the production of biogenic amines in cheeses were studied in this thesis. The quantity of biogenic amines was measured in cheeses after 12, 36 and more than 52 weeks'storage, in order to provide theoretical guidelines for industrial production of fresh cheese, ripened cheese and processed cheese.First of all, different starters were studied as a factor of the production of biogenic amine in cheeses after determining the process of cheese making, extraction of rennet enzyme, measuring of rennet enzyme rennet. Three starters R704, RA024, R011 were studied. R704 and RA024 produce less biogenic amine, and it took more time to reach the toxic threshold value compared to R011. The ability to produce acid of R011 and R704 were different. Starter R011 produce acid faster and the flavor more pungent than R704. R704 was chosen taking all above into consideration.Secondly, pH value and production of biogenic amines were studied in fresh cheese without starters and cheese added starters in 12℃during 12 weeks'storage. The quantity of biogenic amines in the two kinds of cheeses increased along with storage time. The quantity of biogenic amines in cheeses with starters was higher than the cheeses without starters, the quantity of biogenic amine in the two kinds of cheeses above was below the toxic threshold value. The pH value of fresh cheese without starters was 6.73~6.83, relatively high but very stable.While pH decreased during 3 months storage for cheese with starters. Meanwhile, some factors associated with the production of biogenic amine were taken into consideration, quantity of biogenic amine such as pH,moisture content, NaCl content, preservatives(potassium sorbate), starters etc, as well as the interactions of the factors above. The production of biogenic amine was high in cheeses with a high moisture content, high pH, high mass fraction of NaCl, while cheeses with 0.2% potassium sorbate produced less biogenic amine.Finally, cheeses after 12 weeks storage were studied. Results indicated that pH value in cheeses reach rock bottom at the time of the 12th week and afterwards started increase. But after 28 weeks, it increased more and more slightly and then became stable in cheeses at the 36 weeks. The quantity of biogenic amine in cheeses fluctuated sharply early in ripened phase, but increased slightly in general, reached 1310.68mg/kg around 27 weeks and then started to decrease. The quantity of biogenic amine in cheeses had not much to do with moisture content during the first 12 weeks'storage, but it got larger after 12 weeks storage. Moisture content had a positive correlativity relation with the quantity of biogenic amines. NaCl had a restrain effects on production of biogenic amines in cheeses. Mass fraction of NaCl (1%, 2%, 3%) in cheeses affect biogenic amines quantity slightly during the first 30 weeks, but it became an important factor after 30 weeks. Production of biogenic amines in cheeses could be restrained by adding 0.2% potassium sorbate during 8~15 weeks, whose effect was weakened after 20 weeks storage.During the 104 weeks'storage,biogenic amines accumulated in a high amount in 60 weeks. Biogenic amine quantity of the 60th week reached a maximum of 3500mg/kg which was highly above the safe content of 1000mg/kg. Biogenic amines quantity began to decrease to 100mg/kg after 80 weeks storage.