Enhancing microbiological safety of fresh orange juice by fruit immersion in hot water and chemical sanitizers

Abstract

Trials were conducted with hot water and chemicals to sanitize Valencia oranges contaminated by natural microflora or inoculated with Escherichia coli. Microbial loads and sensory quality of fresh juice extracted from surface-heated fruit were also evaluated. E. coli on fruit surfaces was reduced by either hot water or chemical treatments. An estimated 5-log reduction of E. coli was attained by immersing inoculated fruit in hot water at 80°C for 1 min or 70°C for 2 min. Immersing inoculated fruit in various chemical solutions at about 30°C for 8 min only reduced E. coli by about 1.8- to 3.1-log cycles on nonstem-scar surfaces of the fruit. In general, both hot water and chemical treatments were less effective at removing microflora from the stem-scar area. Rapid hot-water immersions at 80°C for 1 min and 70°C for 2 min reduced both fruit-surface and initial juice microbial loads without altering original sensory quality of fresh juice.