Effect of short wave length UV-C irradiation on polyphenols and vitamins in liquid foods: Mechanism and kinetic of degradation
UV-C technology is a novel non-thermal disinfection technique which is being considered as an alternative to pasteurization of liquid foods. This study investigated the effect of UV-C irradiation on the individual polyphenols, vitamins and other nutritional attributes of apple juice. Dose validation was performed through biodosimetry where a challenge organism MS2 was used. Four different polyphenols: chlorogenic acid, phloridzin dehydrate, catechin, epicatechin and ten B vitamins (riboflavin, thiamine hydrochloride, pyridoxal hydrochloride, pyridoxine, pyridoxamine dihydrochloride, cyanocobalamin, choline chloride, biotin, niacin, niacinamide) along with lumichrome were investigated and quantified by LCMS method of determination. The first investigation documented the effect of UV-C irradiation of doses (0-240) mJ.cm-2 on pure apple juices where UV-C doses at lower energy level (0-40 mJ.cm -2) had no significant (p>0.05) effect on major polyphenols, total phenol content, major sugars (glucose and fructose) and antioxidant activities of apple juice. Similar results for polyphenols were found in the second investigation where apple juices were irradiated with doses (0-150) mJ.cm-2, however all vitamins and lumichrome were sensitive to the UV-C exposure, they degraded significantly even at low doses of 20 and 40 mJ.cm-2. Degradation kinetics of vitamins were explained by exponential decline [single first order (SFO)] and sum of biexponential decline functions [double first order in parallel (DFOP)]. Cytotoxicity study showed that UV-C treatment did not cause any harmful cytotoxic effect to normal intestinal cells, and both irradiated and non-irradiated samples exhibited very similar significant inhibitory effects on the growth of human colon cancer cells. The effect of advanced oxidation process using hydrogen peroxide and UV-Irradiation (0-100 mJ˙cm-2) was investigated on polyphenols and in-vitro antioxidant activity including total phenols. Results showed concentration of polyphenols (chlorogenic acid, phloridzin dehydrate, catechin) did not change significantly (p>0.05) as a function of dosage, and also the changes in the content of total phenolics and total antioxidant activities were very minor (<3.0%) at the recommended level of irradiation doses (40 mJ.cm-2). The overall results of this study showed the effectiveness of the UV-C technology at commercially relevant doses for treating highly turbid liquid foods such as apple juice.
Md Shajedul Islam,
"Effect of short wave length UV-C irradiation on polyphenols and vitamins in liquid foods: Mechanism and kinetic of degradation"
ETD Collection for Tennessee State University.