ABSTRACT
Traditionally, ozone processing within the food industry has focused on solid foods by either gaseous treatment or washing with ozonized water. However, with the FDA's approval of ozone as a direct additive to food, the potential for liquid applications has emerged. This study investigates the effect of ozone processing on microbial inactivation (E. coli ATCC 25922 and NCTC 12900) and quality parameters (color, phenolic content) of cloudy apple juice. Apple juice samples were ozonated at room temperature (20 ± 1.5 °C) with a generated ozone concentration of 0.048 mg O(3) at a constant flow rate of 0.12 L/min and treatment time of 0 to 10 min. E. coli inactivation kinetics in apple juice were described quantitatively by using the Shoulder log-linear and the Weibull model. Ozone treatment of E. coli in apple juice demonstrate that a desired 5 log reduction can be achieved within 5 min. Apple juice color (L*, a*, and b*) and total phenols were significantly affected by ozone concentration and treatment time.
Subject(s)
Beverages/analysis , Beverages/microbiology , Food Preservatives/pharmacology , Malus/chemistry , Malus/microbiology , Ozone/pharmacology , Chromatography, High Pressure Liquid , Cinnamates/analysis , Colony Count, Microbial , Escherichia coli/drug effects , Escherichia coli/growth & development , Flavonoids/analysis , Food Preservatives/adverse effects , Food Preservatives/chemistry , Fruit/chemistry , Fruit/microbiology , Hydrogen-Ion Concentration , Kinetics , Microbial Viability , Models, Biological , Osmolar Concentration , Ozone/adverse effects , Ozone/chemistry , Phenols/analysis , Pigmentation/drug effects , Polyphenols , Quality Control , Stress, PhysiologicalABSTRACT
In this study, the polyphenolic composition of skin-on apple wedges from ten cultivars was examined during chill storage and over two growing seasons. Individual polyphenol compounds were measured using HPLC resulting in the total polyphenolic index (TPI). Total phenolic content (TPC) was quantified using the Folin-Ciocalteu assay. Chilled storage had a significant effect (P < 0.001) on the polyphenol composition of all ten cultivars grown in 2007 and 2008. Total phenolic indices (sum of individual polyphenols) and TPCs of nine of the ten cultivars significantly decreased (P < 0.001) after 5 days of storage at 2-4 degrees C. These indices increased in case of Shampion apples over the same storage period. Changes in the most abundant compounds (-)-epicatechin, procyanidins and chlorogenic acid were largely responsible for changes in overall TPI. Percentage loss was higher for compounds such as phloridzin with a degradation of up to 100%. Irrespective of the different starting level of specific polyphenols in each year; storage resulted in a similar percentage loss/gain for each cultivar.
