title: Determination of optimum pH and temperature for pasteurization of citrus juices by response surface methodology.
abstract: Optimization of microbial death, enzyme inactivation and vitamin C retention during pasteurization of pH-adjusted orange juice is discussed free of equipment-dependent parameters such as the heating lag. The pH-temperature optimum was determined by response surface methodology in the range of 65 degrees C-75 degrees C and pH 2.5-4.0. The results implied that there was no pectinesterase activity below pH 3.5. Leuconostoc mesenteroides had its maximum and minimum thermal resistance at pH 3.5 and pH 2.7, respectively. For an ideal theoretical process requiring four log cycles of microbial reduction the optimum pasteurization conditions were 12 min at 75 degrees C and pH 2.7.
authors.affiliation: Food Engineering Department Middle East Technical University, Ankara, Turkey.
authors.forename: N
authors.initials: N
authors.lastname: Ulgen
authors.forename: M
authors.initials: M
authors.lastname: Ozilgen
mesh_terms: D001205:Ascorbic Acid / Q000378:metabolism; D001628:Beverages / Q000592:standards*; D002265:Carboxylic Ester Hydrolases / Q000037:antagonists & inhibitors; D002957:Citrus / Q000201:enzymology / Q000382:microbiology* / Q000592:standards; D005516:Food Microbiology; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D007934:Leuconostoc / Q000254:growth & development; D012044:Regression Analysis; D013242:Sterilization / Q000379:methods*; D013997:Time Factors
chemical_list: D002265:Carboxylic Ester Hydrolases; C022323:pectinesterase; D001205:Ascorbic Acid