First International Conference on MOLDAVIAN RISKS – FROM ...

<strong>First</strong> <strong>International</strong> <strong>Conference</strong> on MOLDAVIAN RISKS - FROM GLOBAL TO LOCAL SCALE
16-19 May 2012, Bacau, Romania
RISK EXPOSURE ON NONIONIZING RADIATION
ASSOCIATED WITH VARIATION OF LACTOSE AND
PROTEIN CONCENTRATION IN DAIRY PRODUCTS
Irina Ifrim 1 , Iuliana Lazar 1 , Marius Stamate 2
1 ”Vasile Alecsandri” University of Bacau, Department of Chemical and Food Engineering
2 ”Vasile Alecsandri” University of Bacau, Department of Mechanical and Environmental
Engineering
Corresponding author: Iuliana Lazar, ilazar@ub.ro
Abstract: The quantity of carbohydrates, fats or proteins is important for the metabolic
process of bodies. There are some of carbohydrates that have a special role in the body.
For example, lactose helps the absorption of calcium and ribose and is a part of the
important compounds DNA-2 and RNA-3. Under the action of lactic bacteria, lactose is
subjected to fermentation processes, the most important being: lactic, alcoholic, propionic
and butyric fermentation thus resulting in important changes in physical, chemical and
organoleptic properties of milk products. The aim of our study is to highlight the
conditions in which might appear alteration of lactose and protein in the presence of milk
inoculated with lactic acid bacteria (LAB) and nonionizing radiation exposure. The
analysis was achieved for milk inoculated with LAB ranging from 0.1g/l to 0.5g/l and
under UV-VIS radiation doses (D) that varies between 29kJ/m 2 and 165kJ/m 2 . HATR-
FTIR spectral interpretation of vibrational group frequencies was performed with OPUS
6.0 Bruker and ORIGIN 8.50 software. Data mining in correlation with spectral data
technique provides us the information about the lactose and proteins variation in the
samples exposed to stress factors. The degree of proteins denaturation depending on the
temperature and duration of its action is observed. At a concentration of 0.1g/l of lactic
acid bacteria we have found a maximum of the relative amount of lactose (L) and at 0.4g/l
a minimum one. Up to a dose of 97kJ/m 2 the L growth is slow, after which the exponential
growth occurs. The relative amount of protein (P) shows a minimum at a concentration
LAB at 0.2g/l and a maximum at 0.5g/l. Also it was observed that exposure dose variation
fits very well on a logistic regression curve. MANOVA test reveals that there is a
significant multivariate effect of LAB on L (Pillai coefficient F = 3.978, p