食品化学课件 Topic 2-1 FScN-4112-12 water physics.pdf

FSCN 4112 Food Chemistry Topic 1-1 2012 Physical-Chemical properties of water important for foods Dr Ted P. Labuza Department of Food Science and Nutrition University of Minnesota St Paul 55108 USA 612-624-9701 fax 625-5272 tplabuza@ tplabuza © 2005 Slide # 1 Guess the melt time tplabuza © 2005 Slide # 2 Water in foods •  Serves a nutrient •  Creates texture - eg gels, crisp crackers, ice cream cones, bread, chocolate chip cookies, puffed or extruded cereals •  Serves as reaction phase for chemical degradation,vitamin loss, bioactive loss •  Serves as a phase for microbial spoilage tplabuza © 2005 Slide # 3 Water Control Preservation processes •  dehydration - Contact dry air over food or dry in vacuum •  on farm - cereals/ plants/ seeds/spices / herbs/botanicals •  many processed foods and ingredients e.g. dry soups, infant formula, instant coffee •  drugs (e.g. spray and freeze drying) •  germ plasma, biologics, botanicals •  starter cultures yeast •  forensic samples (semen, DNA) •  paper, wood, adhesives tplabuza © 2005 Slide #4 Water control Preservation processes •  deep fat frying - boil off water •  extrusion - corn curls •  gun puffing - puffed rice •  baking