7. Food Processing and Engineering Flashcards
Full name of WVTR?
Water vapor transmission rate
Isotherm water activity chart, x and y axis?
x: water activity y: moisture content
Define triple point?
Pressure-Temperature at which substance is at solid liquid and vapour phase at same time. For water is 611.73 Pa and 273.16 K.
In thermoprocessing what is the difference between sterility and commercial sterility?
Commerical sterility means the probability of spores and cells surviving is low but not absolute
Name 3 methods of food preservation
Drying/salt addition/heat/freezing
The most commonly used surfactants in the food industry are?
Monoglycerides and Diglycerides
What is IQF?
Individually Quick Frozen
Which test would you use to determine whether Coke is sweeter?
Increasing foam stability but decreasing foam value
Of the 4 components of a refrigeration system, which one involves constant entropy?
Compressor
Basic Principles of Food Processing
1) Moisture removal
2) Heat treatment
3) Low-heat treatment
4) Thermal processing
5) Nonthermal processing (traditional & nontraditional)
6) acidity control
What is the purpose of processing Food?
To preserve food and create a specific desirable food product
What is Food Spoilage?
Perishability of raw foods through microbial growth/enzymatic reactions/chemical changes (mainly through factors of water/temp/pH)
What is Unit Operations?
The processing step of a product like in a factory (i.e. heat exchange - evaporation - drying - material handling)
What is Heat Treatment?
Process of inactivating pathogens and spoilage microorganisms and enzymes
What is D-value?
The specific time at a specific temperature for a specific food to destroy 90% of the population (one log) of a specific MO
What is the 12D Concept?
The D-value to destroy 90% of C. Botulinum at a 12 log reduction: ensures safety of low acid foods
What is the purpose of thermal death time studies?
to determine an organism’s heat resistance (D-value) in a specific product to develop a process for that product
Define Acidity Control
The more acid present in a food the lower the pH becomes lowering the potential of microbial spoilage and requires less heat treatments
What is Traditional Nonthermal Processing?
Chemicals added to food for preservation to control aW and extend shelf-life through packaing
Name the Types of Traditional Nonthermal Processing
1) modified atmosphere packaging (MAP) 2) controlled atmosphere storage (CAS) 3) nitrogen flush packaging 4) vacuum packaging
What is Innovative Nonthermal Processing?
Refers to new technologies that preserve the food supply without raising the temperature; to eliminate thermal degradation of food quality
What is blanching?
Process used to inactivate enzymes and set color
What is Pasteurization?
Process used to inactivate pathogens (e. coli) and vegetative (alive) pathogens
What makes a product commercially sterile?
Free of all pathogens and other microorganisms that could potentially grow in the product
Why is commercial sterilization important?
To achieve long-term shelf stability for canned foods and other products: majority after being placed in container
What is conduction heating?
Uniform heating of the product from all directions with the slowest or coldest location at or near the center of the container
What is Convection heating?
(canned liquid) the first heated portion of the liquid becomes lighter in density and rises thereby setting up circulation within the can. coldest location at bottom of container
What is the purpose of refrigeration storage?
To extend shelf-life by slowing down derogatory reactions and limiting microbial growth
What is the refridgeration temperature range?
Temperature range - approximately -1 to 8 C
What are some ways of deterioration of product quality?
Chemical/Biochemical/Physio-chemical/Nutritinal
Name the 4 Biochemical reactions of product quality
Enzymic browning/Glycolysis/Proteolysis/Lipolysis
What is the Freezing/Frozen temperature range?
Freezing below the temp. at which ice crystals begin to form within the food -10 to -20C
Name 2 food freezing systems
Indirect contact and direct contact
Define Heat capacity
the amount of heat necessary for a unit mass of substance to change its temperature by one degree. Heat capacity is really a measure of how fast we can heat or cool a material
Define specific heat
the ratio of the heat capacity of a substance to that of water
Define Sensible Heat
the amount of heat added to or removed from a substance that results only in a change in temperature it takes into consideration the mass of the material and heat capacity
Define Latent heat or hidden heat
the amount of heat energy transferred to or from a material and results in phase change only without changing its temperature
What is thermal conductivity?
How heat penetrates the food when freezing the food. It takes into consideration Mw/solids/fat/general composition of the food product
What is HTST full name?
High temperature short time
A substance that has a high affinity for water?
Humectant
What is the stabilization factor for colloidal suspension?
Particle size/Viscosity/Electrostatic interaction
What are the three modes of heat transfer?
Conductive/Convective/Radiation
Which category of food materials can be heated by microwave?
Dielectric material
What are the two common polymerization methods?
Addition polymerization and condensation polymerization
In extrusion which surface is rough and which one is smooth? Inside surface of barrel or outside surface of screw?
The inside surface of barrel is rough and outside surface of screw is smooth
What does commercial sterilization refer to?
The use of a thermal process to achieve a shelf stable food product
What concept motivates the use of multiple preservative factors to prevent growth of pathogens in processed foods?
The hurdle concept
What are SOP and SSOP?
Standard Operating Procedure
Sanitation Standard Operating Procedures
Which enzyme is commercially used to produce maltose by hydrolyzing starch?
Beta-amylase
In sugar refining process what is the function of earth and charcoal?
Decolorize
explain D value
the decimal reduction time or the time required to destroy 90% of microorganisms
microwave heating is accomplished by _______
molecular friction
which of the procedures listed is designed to kill most microorganisms: A.radappertization B.radicitation C.radurization?
A. radappertization
Milk is sometimes concentrated using RO and UF equipment - What do these abbreviations stand for?
RO=reverse osmosis UF=ultra filtration
List 2 approved application of gamma irradiation in foods
Inhibit sprouting in tubers and bulbs
Reduce microbial population in spices
Destruction of salmonella in poultry
Destruction of spoilage microorganisms
name 2 non-thermal food processing technologies.
UV light Ultrasound High pressure Pulsed light Pulsed electric field Irradiation Infrared
what does the acronym NFPA stand for?
National Food Processors Association
what is the term for an ingredient that is added during processing that is later during shipping/handling/storage is altered/removed/diminished?
a processing aid
what kinds of acids are the most effective acid-based antimicrobial preservatives in foods?
weak organic acids because only undissociated acids can cross the cell membrane
Describe the flow direction of water across a cell membrane in an isotonic - hypotonic - hypertonic solution
Isotonic=no net flow (equilibrium)
Hypotonic= water flows into the cell
Hypertonic= water flows out of the cell
Classify the following as either endothermic or exothermic: melting-condensation-evaporation-boiling-freezing-crystallization
Melting=endo Condensation=exo Evaporation= endo Boiling= endo Freezing= exo Crystallization= exo
Describe the difference between alcoholic fermentation and tea fermentation
Alcoholic fementation is through the addition of bacteria or yeast to grapes or hops resulting in the transformation of sugar to alcohol. While tea fermentation is oxidation where the leaves are exposed to air and can be controlled by adding heat through pan firing or steaming in this process the chlorophyll carotenoids and lipids in the leaves are enzymatically broken down and its tannins are released or transformed.
Name the two frequencies of microwaves for industrial heating during food processing
2450 and 915 MHz
A plate freezer is a direct or indirect freezing method?
indirect
What does MSM stand for in the context of meat?
Mechanically separated meat
What are 3 things removed during filtration of milk?
Some bacteria/somatic cells/sediments
What does TDT stand for?
Thermal Death Time
What is the type of irradiation used to produce commercial steril food?
Radappertization
Time (in seconds) for High Temperature Short Time pasteurisation at 71.7C?
15
What gas often removed from package during thermal processing?
Oxygen
What is the type of rays used for food irradiation?
Gamma-rays
Phases of colloidal dispersion?
Continuous phase or dispersion medium and dispersed phase or internal
Colligative properties of water?
Freezing point/Boiling point/Vapor pressure/Osmotic pressure. Properties that depend on the number of solute molecules in water.
The viscosity of egg white decreases with shearing force. What rheology terms describes this?
Pseudoplastic
What are the four variables used when calculating the Reynolds number of a fluid?
D=pipe diameter V=mean fluid velocity rho=mass density mu=fluid viscosity
What are the factors that affect thermal processing?
- Product pH or acidity
- Heating and cooling characteristics
- Size of container
- Heating and cooling medium
- Time/temperature relationship
- Product composition
What are the 3 pH parameters of food?
Low acid over 4.5
Medium acid and acid 3.7 to 4.5
High acid below 3.7
What are the changes caused by refrigeration?
Retard microbial growth
Limit lipid oxidation
Limit non-enzymatic browning and enzymatic browning Slow down sugar conversion
Reduce respiration reactions
What are the 4 phases of refrigerated storage?
Commercial storage, Transport storage, Retail storage, Home storage
What are some reasons for refrigeration combining methods ?
Combined refrigeration with other preservatives techniques to enhance shelf life, MAS (Modified Atmosphere Storage)
What can be used to define changes in quality?
Degradation of pigments, Loss of vitamins, Enzyme activity, Oxidation of lipids
Fruits can be classified according to their respiratory patterns. List 2 climacteric fruits
Apple, apricot, avocado, banana, mango, papaya, passion fruit, papaw, peach, pear, plum, tomato, watermelon
Fruits can be classified according to their respiratory patterns. List 2 non-climacteric fruits
Blueberry, cacao, cherry, cucumber, fig, grapefruit, lemon, grapes, melon, orange, pineapple, strawberry, tamarillo
What is the purpose of Low-Temperature Treatment?
A) slows spoilage reactionsB) freezes the water in food to reduce aW
