LFS 100 Lecture Notes - Lecture 7: Freeze-Drying, Odwalla, Spray Drying
Document Summary
Thermal methods: high temperature (canning, pasteurization, blanching, microwave) Milk heat treatment for fruits and vegetables. Wilt vegetables to facilitate packaging prior to freezing or canning. Moderate heat treatment of liquid products: low temperature (refrigeration, freezing) Reduction of water content: concentration (evaporation, membrane processing, freeze concentration, dehydration (spray drying, freeze drying, oxygen control (packaging) radiation. Chemical preservation: solute addition; water activity control. Commercial sterilization: destroy all microorganisms of commercial significance and produce a shelf-stable product, canning - in-container, uht: aseptic processing & packaging - out of container, continuous, disadvantage: destroys taste. Pressure canning: low acid foods: >121 degree celsius, high acid foods: Treated w/ 100 degree celsius boiled water: low acid foods. Identifying the d value (time required at a given temp for 1 log cycle reduction in numbers) D72 = 1 min = for each minute of processing at 72 degree celsius, the population will decrease. Produce surfaces provide protection for pathogens to hide.
