FINALS

• Salting


  Modifies environment to be undesirable for microbial growth
• Moisture content


  Total water<|>Based on wet basis (mass of water/total mass)<|>Dry basis (mass of wet solid/mass of dry solid)<|>Mc = mass of H2O in wet solid/total mass of solid<|>Mc = mass of H2O in dry solid/total mass of solid
• Water activity (aw)


  Directly relates to the concentration of solutes within the system<|>Relates to the availability of that water for microbes to use in their growth and reproduction<|>aw = vapor pressure above the food/vapor pressure of pure water
• Water activity (aw)


  • Lower aw lower growth
  • 0.60 - 0.85 yeasts and molds
  • 0.70 - bacteria high moisture
  • High temperature, low water activity
• Salting


  1. Objective is to ensure rapid salt penetration to lower water activity in deepest parts of food

  2. Achieves saline equilibrium between muscle and surrounding salt solutions

  3. Maximum concentration is saturated brine solution (around 26%)

  4. Salted fish has theoretical aw of 0.75
• Salting process


  • Dry - salt physically/directly applied to food
  • Wet - food immersed in brine or pickling solution
  • Hybrid/Combination
• Brining


  1. Concentration of salt is sufficient for flavoring purposes only

  2. Preservation done by other methods

  3. Food treated for several minutes in less saturated brine

  4. Elutes soluble proteins for attractive, glossy pellicle
• Pickling


  1. Immersion in concentrated brines for longer period

  2. Used for longer term preservation, mainly of fatty fish

  3. Restricts oxygen access to retard rancidity
• Kench curing


  1. Dry salting method

  2. Fish split, opened flat and placed in layers with salt

  3. Liquor exuded is allowed to drain away

  4. Used for white, non-fatty fish
• Gaspe curing


  1. Combination of dry and wet salting

  2. Exudant liquor not allowed to run away, fish float in brine

  3. Weights used to keep fish immersed for 2-3 days, then dried
• Salt brine injection


  Wet process that injects brine solution into food
• Packaging and storage requirements

  • Glass or vacuum packaging
  • Requires aw 0.75 or below
  • Intermediate moisture food
  • Does not necessarily require refrigeration
• Smoke production


  Lower temperature and less oxygen give smoke with more flavoring and preserving substances<|>Higher temperature and more oxygen waste these substances
• Smoke sources


  • Wood - makes hotter fire but less smoke, charring fish
  • Sawdust - smoulders rather than burns, producing more smoke
• Important chemical components of smoke

  • Nitrogen oxides
  • Polycyclic aromatic hydrocarbons (PAHs)
  • Phenolic compounds
  • Furans
  • Carbonylic compounds
  • Aliphatic carboxylic acids
  • Tar compounds
• Antioxidant


  Combats action of free radicals by donating an extra electron to stabilize them
• Radicals


  Free in nature, highly reactive (e.g. superoxide O2)<|>Have unpaired electrons
• Steps in smoking


  1. Pre-treatment:

  2. Splitting and cleaning

  3. Salting - product may be soaked in strong brine, permitted colors added, contact time depends on size/fat content, 70-80% saturated brine common

  4. Drying/Hanging
• Packaging and storage requirements for smoked foods

  • Water activity of 0.7 or below can be stored at room temperature
  • Composite/plastic packaging
• Food irradiation


  Process that exposes food to electromagnetic radiation or high energy particles to produce safe and longer shelf-life foods<|>Food products rendered as stable upon exposure to ionizing radiation<|>Negative consumer acceptance due to misconception of radioactive substances
• Radiation


  Transmission of energy coming from a source that travels at the speed of light<|>Has electric and magnetic fields and wave-like properties
• Tractive, powdery salt crystals


  • On the surface of the finished product
• 50% saturated brine


  Causes the fish to swell such that excess water would have to be evaporated off during drying
• Brines


  1. Must be kept to strength

  2. Should be changed at least once per day
• Water activity of 0.7 below

  Could be stored at room temperature
• Composite packaging


  Combination of different packaging materials
• Food irradiation


  Process that exposes food to either electromagnetic radiation or high energy particles with the aim of producing safe and longer shelf-life foods
• Food products rendered as stable upon exposure to ionizing radiation
• Negative consumer acceptance - common misconception – radioactive substances
• Radiation


  Transmission of energy coming from a source that travels at the speed of light, with an electric and magnetic field and wave-like properties
• KiloGray (kGy)


  Unit/dose of radiation; A dosage of one kGy indicates that the target sample receives 1000 Joules (metric units of energy, abbreviated J) per kilogram of sample mass
• Ionizing radiation


  A form of energy that acts by removing electrons from atoms and molecules of materials that include air, water, and living tissue, and can travel unseen and pass through these materials
• Sources of ionizing radiation

  • Microwaves
  • Ultraviolet rays
  • X-rays
  • Gamma rays
• Gamma Rays


  Uses radioactive isotopes (Cesium 137 and Cobalt 60)
• High Energy Electrons


  Operated by electricity, do not use radioactive isotopes
• 1. rays


  Operated by electricity, do not use radioactive isotopes
• Low Dose


  • Less than 1 kGy
  • Used to control insects, trichinae (parasitic worms in pork) and controls ripening and sprouting of fruits and vegetables
  • Also termed RADURIZATION (similar to pasteurization treatment), causes substantial reduction in the no. of viable spoilage microbes
  • Sprout inhibition in bulbs and tubers- 0.03-0.15 KGy
  • Delay ripening of fruits – 0.25-0.75 KGy
  • Insect disinfestation including quarantine treatment and eliminate foodborne parasites
• Medium Dose


  • 10 kGy
  • Used to control both spoilages causing micro and bacterial pathogens, also effective against foodborne pathogens
  • Also termed as RADICIDATION (similar to pasteurization)
  • Reduction of spoilage microbes to prolong shelf life of meat, poutry and seafood under refrigeration tempt. (1.5- 3.0 kGy )
  • Reduction of pathogens in fresh and frozen meat, poultry and seafoods (3.0- 7.0 KGy)
  • Reduction in no. of micro in spices (10 kGy)
• High Dose


  • Greater than 10 kGy
  • Used to control microbial contamination of spices, enough heating is required to deactivate enzymatic action
  • Termed as RADAPPERTIZATION; equivalent to commercial sterility or Thermal Processing (with levels up to 30-40 kGy) if hermetic sealing
  • Is not isotope radiation
  • Targets water molecules of food (vibrates)
  • No contact of workers
  • Food comes, delivered to conveyor inside the facility, then radiation source, comes out at opposite side
• Microbial inactivation mechanism of gamma irradiation

  1. Gamma rays from 60C emitter have the capacity to penetrate structures and microorganisms

  2. The gamma rays damage the microbial DNA inactivating the cell