《食品加工原理》课程PPT教学课件（福建农林大学）Chapter 7 LIQUID CONC

LIQUID CONCENTRATION ◼ EVAPORATION ◼ MEMBRANE SEPRATIONS ◼ FREEZE CONCENTRATION

LIQUID CONCENTRATION ◼ EVAPORATION ◼ MEMBRANE SEPRATIONS ◼ FREEZE CONCENTRATION

Vocabulary ◼ Concentration, dehydration, vital, evaporation , membrane concentration. freeze concentration, reverse osmosis, ultrafiltration, fruit juices or purees, semiporous membrane, permeability, ice crystal slurry, coffee and tea extracts, volatile flavors and aromas, centrifugal force, droplets, entrained, agitation, buoyancy, gravity

Vocabulary ◼ Concentration, dehydration, vital, evaporation , membrane concentration. freeze concentration, reverse osmosis, ultrafiltration, fruit juices or purees, semiporous membrane, permeability, ice crystal slurry, coffee and tea extracts, volatile flavors and aromas, centrifugal force, droplets, entrained, agitation, buoyancy, gravity

Vocabulary ◼ flexibility viscosity sanitation bulk transport semipermeable equilibrate equilibrium migrate osmotic pressure feed permeate retentate solution solute solvent flux solubility polarization

Vocabulary ◼ flexibility viscosity sanitation bulk transport semipermeable equilibrate equilibrium migrate osmotic pressure feed permeate retentate solution solute solvent flux solubility polarization

Concentration of liquid foods ◼ Concentration of liquid foods is a vital operation in many food processes. Concentration is deferent from dehydration,. Generally, foods that are concentrated remain in the liquid state, whereas drying produces solid or semisolid foods with significantly lower water content

Concentration of liquid foods ◼ Concentration of liquid foods is a vital operation in many food processes. Concentration is deferent from dehydration,. Generally, foods that are concentrated remain in the liquid state, whereas drying produces solid or semisolid foods with significantly lower water content

7.1 table General Characteristics of Liquid Concentration Types of materials for concentration Fluid foods Water loss Molecular and eddy transport within fluid being concentrated Convective mass transfer from fluid surface to environment Characteristics of concentrated products Water content typically >20-30% Product still flows as liquid Types of operation Continuous,steady-state operations used on commercial scale Small-scale operations may be batch (unsteady state)

Liquid Concentration Technologies ◼ Several technologies are available for liquid concentration in the food industry, with the most common being evaporation and membrane concentration. Freeze concentration is another technology that has been developed over the past few decades, although significant applications of freeze concentration of foods are limited

Liquid Concentration Technologies ◼ Several technologies are available for liquid concentration in the food industry, with the most common being evaporation and membrane concentration. Freeze concentration is another technology that has been developed over the past few decades, although significant applications of freeze concentration of foods are limited

72 a▣ Sue Common Liquid Conceulration Technolugies Used Foud Processing Terhuniney S间ling Agent Principle af Separation Producle Exapeatinm Heal IifFerence in volatilities Liquid and vapnr 〔vupor pressure) Flash expataion Pressure rednetin Dilfererec in volatilities Liquid and vapur 〔vapor pressure Distillalion Heal Ditfercnees in rolatilitics Liquid and vaput Rererse osmosis Pressure gradienl Dhitferent combined 2 liquid products Seterive membrane solubilities and dilusivilie of species io rembrane Cllrufi]tration Pressure gradieul Diletenl permeabiliries 多]iqui闲prod加cts Selective membrane ihreugh memhranes Diysis Seleclive membrate Differeul rates of diffusiona] 3 liquid products Solvenl Iranspait through memhrane Electrodialysis lonie membranes Selectivity of iouic membranes 2liquid pruduets Electric lield to apecific ionic spceics 门ee2共outenmano0 Refrigeraut Sclective crystallizution of Liquid coucentrate pure walcr and pureie

Evaporation Concentration ◼ Evaporation concentration means removal of water by boiling. Evaporation finds application in a variety of food processing operations. A primary application is concentration of fruit juices (orange juice concentrate), vegetable juices (tomato pastes and purees), and dairy products (condensed milk). Evaporation is also used to concentrate salt and sugars prior to refining

Evaporation Concentration ◼ Evaporation concentration means removal of water by boiling. Evaporation finds application in a variety of food processing operations. A primary application is concentration of fruit juices (orange juice concentrate), vegetable juices (tomato pastes and purees), and dairy products (condensed milk). Evaporation is also used to concentrate salt and sugars prior to refining

Membrane Separation Concentration ◼ The basis for membrane separations is the difference in permeability of a semiporous membrane to different molecular sizes. Smaller molecules pass through these membranes more easily than larger ones. Since water is one of the smallest molecules, concentration is easily accomplished using membranes with appropriate molecular￾weight cutoffs

Membrane Separation Concentration ◼ The basis for membrane separations is the difference in permeability of a semiporous membrane to different molecular sizes. Smaller molecules pass through these membranes more easily than larger ones. Since water is one of the smallest molecules, concentration is easily accomplished using membranes with appropriate molecular￾weight cutoffs

Freeze Concentration ◼ Water is partially frozen to produce an ice crystal slurry in concentrated product. Separation of ice crystals is then accomplished using some washing technique. Current applications of freeze concentration are limited to fruit juices, coffee, and tea extracts, and beer and wine. Freeze concentration produces a superior product

Freeze Concentration ◼ Water is partially frozen to produce an ice crystal slurry in concentrated product. Separation of ice crystals is then accomplished using some washing technique. Current applications of freeze concentration are limited to fruit juices, coffee, and tea extracts, and beer and wine. Freeze concentration produces a superior product