Food Science 241 - Test 3

What types of foods are heated by conduction and convection?

Foods containing starch in which food leaks starch, syrup packed sweet potatoes, and ream style corn

What is the most common sterilizing agent?

Steam

What is commercial sterilization?

All pathogen and toxin-forming and spoilage organisms that could grow under normal conditions

What are the three pieces of the microwave?

1. Cabinet 2. Fan (Distributes waves as they bounce of metal) 3. Magnetron (electron tube within magnetic field that that produces high frequency radiant energy

What requirements are placed on linings?

1. Cannot impart flavor 2. Must protect can and contents 3. Must be acceptable for food use 4. Must not flake off 5. Must withstand processing temperature

What are the 8 steps of canning?

1.Preparation (clean, cut, sort, etc.) 2.Blanching 3.Filling 4.Exhausting (drive air out of food by placing can in hot water) 5.Sealing (lids placed on top by closing machine) 6.Thermal Processing (Commercial sterilization) 7.Cooling (Creates Partial Vacuum) 8.Storage (Place in cool, dry place)

What pressure is needed to bring water to 250F?

15 PSI

What is a beaded can?

A type of can that is strengthened by reinforcing ribs or concentric depressions around the body

Who invented the first retort? When? Where?

AK Shriver invented the first retort(canning under pressure) in 1874 in Maryland

What is necessary for the complete heating of all food particles? Why?

Agitation; It increases the rate of heat transfer

What doses of radiation are needed to kill: animals, insects, non-spore forming bacteria, bacteria spores, viruses

Animals: 0.005 to 0.1 kGy Insects: 0.01to 1 kGy Non-spore forming bacteria: 0.5 to 10 kGy Bacteria Spores: 10-50 kGy Viruses: 10-200 kGy

What is thermal processing?

Applied heat to foods in container for period of time and at given temperature in order to commercially sterilize

What is the approval process of radiated foods in the U.S.?

Approval by FDA on case-by-case basis and sets amounts of radiation allowed.

What are the uses for microwave heating?

Baking (air needed for crust forming and browning), Enzyme inactivate (blanching fruits and vegetables in order to preserve foods), Thawing, Pre-Cooking (for heat and severe products)

What types of heating are used for uneven products? What about in commercial settings?

Batch Heating; Continuous heating used commercial (No need to heat up then cool down)

Describe a still batch retort.

Batch-type, non-agitating pressurized vessel that is the cheapest to use and slowest to cook food. The products are container-stacked or jumbled into retort. It can be vertical or horizontal.

What three instruments are needed to "tear down" and measure double seam?

Can opener, Nippers and Special Pliers, and Micrometer (measures in 1/1000 of an inch)

What foods are usually subjected to commercial sterilization? How long will they last? What happens after they surpass their shelf life?

Canned foods are usually subjected to commercial sterilization. They have a shelf life of 2+ years, but afterwards, they lose texture and flavor.

What organism is the prime target of commercial sterilization?

Clostridium botulinum (neruotoxin-producing anaerobic spore former found everywhere)(needs a pH>4.6; Aw>0.85)

What is a double seam?

Closure formed by interlocking and compressing the curl of the end and the flange of the can

What is sterilization?

Complete destruction of microorganisms; All food particles must be heated to 121C/250F for 15 minutes

What type of heating happens between food particles? Between liquid particles?

Conduction between food particles, and convection between liquid particles.

Describe conventional heating. Microwave heating?

Conventional heating happens from the surface inward (allows case hardening). In microwave heating, waves penetrate uniformally for several centimeters. Prevents case hardening as the temp doesn't go above boiling.

What factors must be considered in microwave heating?

Cost and product quality

What is the D-Value?

Decimal-Reduction Time; Time required for one log cycle reduction of a microbial population at a given temperature

What is Fruit-Enamel?

Developed for use with dark colored fruits like cherries to prevent fading of product's color

What types of food are heated?

Fluid food product and food product with discrete particles = Convection Food particles suspended in viscous liquid = Conduction and Convection Heavy matted food and Solid Particles = Conduction

How are F-Values related to D-Values?

F-Values are multiples of D-Values (Different temperatures result in different times to achieve same level of population death)

What is the F:D value for Clostridium botulinum?

F=12D

True or False: All points inside the can are being heated at the same temperature.

False

True or False: There are unsafe products at low doses, so radiation is not used to pasteurize products, kill insects, etc.

False

What tool is used to remove condensation and prevent drip-back? What foods may want to remove condensation/water?

Fan;Jellies and Jams

What foods are subjected to low dosage radiation?

Fruits and vegetables to kill insects, slow ripening, and inhibit spores (potatoes)

What is the pH of most fruits? Vegetables?

Fruits have a pH less than 4.6. Vegetables have a pH greater than 4.6

What can lead to spoilage within a canned product?

Gas producing microbes (bulging in cans), food held too long in container before or after closing, contamination after processing, inadequate heating, acid tolerant spore formers, non-microbial (reaction with can, overfilling, low or no vacuum, etc.)

What types of cans were first used in retorting? What types are used now?

Glass and ceramic were used at first, but metal cans and plastic pouches among other things.

What factors will affect the effectiveness of microwave heating?

Growth phase of microbes, Fat content of products (Lean products better than fatty products), temperature of food (Frozen better than heated), Absence of oxygen (anaerobic conditions are better)

What is blanching? What processes is blanching generally associated with?

Heat processing used to deactivate enzymes but may destroy some microorganisms; Usually associated with freezing or dehydrating

What is pasteurization?

Heat processing used to destroy foods associated with food; usually less than the boiling point of water (100C/212F)

What is conventional canning?

Heated product is filled into can and then hermetically sealed. The product is then thermally processed.

What is convection heating?

Heating initially from can to products inside can. Energized molecules rise to the top as the cooler ones fall to the bottom. (Cold point at the bottom of the can)

Canned foods are filled ___________ but not _________. Heat is transferred from steam to can by __________ and from ________ to _______. Can contents will heat by ______ or _______.

Hot but not boiling; Conduction; Can to contents; Conduction or convection

Where is the cold point of can heated by conduction?

In the center of the can

What data points must be recorded before the retort process begins?

Initial temperature of the coldest can; Venting retort of all air; Building margin of safety into processing

What types of foods are heated by convection?

Juices, broths, evaporated milk, most vegetables, and fish

What foods are subjected to medium dosages of radiation?

Meat and poultry to reduce spoilage and pathogenic microbes; Spices and herbs to kill bugs and bacteria

What foods are generally subjected to pasteurization? What happens to shelf life of the product after pasteurization?

Milk and eggs. These products still contain microbes and, therefore, have limited shelf life/storage time. Products are generally refrigerated to delay spoilage.

What factors must be considered when making calculations for this process?

Must consider the thermal death times of microorganisms, the type of heating that occurs in foods, and the cold point of the container. This allows one to determine the processing times which are then validated by Inoculated Pack Studies

How many measurements must be taken and how far apart to make double seam measurements? What is the equation?

Must make three measurements at least 120 degrees apart. Overlap = CH + BH + Cover Thickness - Seam Width

Who invented canning and when? Why?

Nicholas Appert invented canning in 1810 by heating glass/ceramic cans for Napoleon because it allowed food to be transported by the military without fear of spoiling.

What foods are subjected to high dosages of radiation?

No foods in the U.S. are allowed to be highly radiated

What concerns are taken into account when evaluating safety of radiating foods?

Nutrient value, production of toxic substances, production of carcinogenic substances, production of harmful radioactivity

What are other types of radiating heat processing?

Ohmic/Pulsed-electric heating: energy is passed through foods by electrodes on opposite ends of foods; ex. hotdogs High Pressured Processing: 40,000-90,000 PSI; disrupts microorganisms through squeezing them; must be unifrom and free of air space

What is aseptic processing?

Packaging and products are separately sterilized, and then the product is then filled into the package.

What are the three stages of the hydrostatic retort?

Preheating->Sterilization->Cooling

What is canning? What foods are generally canned?

Preservation of foods in hermetically sealed containers using heat or sterilization. Meats, fruits and vegetables, soups, seafoods, and baby juices among other things.

Describe agitating continuous retort.

Processor that continually rotates cans/containers to heat foods without harming them. Constructed of continuous shells and packages that are designed to facilitate different types of heating.

Describe a hydrostatic retort.

Processor that operates at a constant temperature and transports containers through processor on chain belt. No valves or sealing mechanisms are used in a hydrostatic retort, but uses pressure of water columns and discharging stations. This is probably the most expensive type of heating process.

Describe an agitating batch retort.

Processor that rotates cans/containers to quickly heat foods with thinner or more liquid foods. Can use vareity of pouches such as glass or plastic.

What are the units of radiation? Conversion?

Rad and gray. 1 Gray = 100 Rad

What symbol is used to denote that a food has been irradiated?

Radura

What considerations must be made when calculating the radiation dose?

Resistance of food to quality damage; Resistance of microorganisms (Clostridium botulinum is most resistant); Resistance of enzymes (Blanching should happen before microwave heating); Cost (Increasing dosage and time increases cost)

What are the heating systems for STOVE, OVEN, and HEATED KETTLE?

STOVE: Burner->Container->Food OVEN: Heating Element->Surrounding Air->Container->Food HEATED KETTLE: Surface of Container->Liquid/Semi-Liquid Food

What is a microwave tunnel oven?

Series of moving belts that moves food past magentrons. Openings at inlets and outlets trap waves within oven, and liquid filled glass coils surrounded by magnetrons used to continuously heat foods.

What types of foods are heated by conduction?

Solidly packed foods like sweet potatoes, SPAM, and concentrated soups

What are the ideal qualities of a container for canning?

Strong enough to protect during shipping, easily fabricated into different sizes, easily opened, light enough for economic handling, impervious to air and water, pleasing and sanitary appearance, not harmful or imparting toxicity to foods, can be heated for sterilization, inexpensive

What must be done to raise the temperature of steam/water above 100C/212F?

System must be pressurized.

What is a tubular heating system?

System that heats liquid foods with uniform texture through thin layers versus large batches using heated water or steam.

What is the downsides of sterilization?

Takes too long to heat completely; would severely degrade the food quality

Who applies the bottom of the can? The top?

The can manufacture applies the bottom of the can. The producer applies the top of the can

What is the goal of heat processing? What factors do you need to know?

The goal should be to use the least amount of heat for the least amount of time. One should know the time-temp combo to kill the microorganisms in a food and the heat penetration characteristics of the food.

What is the F-Value?

Thermal Death Time; Time required to reach a stated reduction in the microbial population at a given temperature

What is the Z-Value?

Thermal Resistance Constant; Temperature increase required to cause one D-Value (Larger Z-Value means that an increase in temperature leads to a smaller change in microbe population and the microbes have a greater heat resistance)

What tool is used to measure heat penetration in can?

Thermocouple

What is a low acid food? What type of processing should be used with this food?

These types of food are acidic but have a pH greater than 4.6 and water activity greater than 0.85. Mild heat processing should be used with these types of food to inhibit spores and kill vegetative cells. Heavy heat treatment needed to kill spore formers.

What adjustments must be made if temperature is increased?

Time decreased

What types of materials are used to make containers?

Tin, aluminum, glass, plastic, and steel (metals have acrylic lining to prevent acids from corroding them)

How many numbers are used to specify the can measurements? In what units?

Two numbers that are in 16ths of an inch (The first number is the diameter. The second number is the height.) (Ex. Can with 307 and 409 would have diameter of 3 7/16 in and height of 4 9/16 in.)

What are microwaves?

Type of electromagnetic radiation that travels in straight lines, are reflected by metals, pass through air, glass, paper, and plastics, and are absorbed by materials such as water (which is heated to heat food)

What is C-Enamel?

Type of lining used for peas, corn, and other sulfurous foods that is used to prevent dark discoloration of foods

What are the different types of kettles? What temps can they reach?

Types: Steam jacketed; Boiling-Water Jacketed; Heated with Electric Coils; Heated with gas flame Temperatures: Water<100C/212F; Steam Jacketed = 100C/212F

What radiation forms are used with foods?

UV Light (Kills microorganisms and treat equipment/water/surfaces/etc.;Low penetration) and X-Rays (Still experimental but have better pentration)

How is ionizing radiation used to preserve food?

Using Co or Cs isotopes/gamma rays from spent nuclear fuel to cold sterilize foods by knocking electrons from orbit, creating free radicals, and altering enzymes and DNA of microorganisms

What foods are very acidic? Borderline? Low acid?

Very acidic: Sauerkraut, pineapple, and pears Borderline: Tomatoes Low Acid: Chicken, corns, beans, and potatoes

What is the role of water molecules in microwave heating?

Water molecules and food particles align with alternating electric field in order to generate friction and intense heat between the food particles

What is the timeline of federally regulated irradiation of foods?

Wheat flour for mold and insects/Potatoes for sprouting (1963) Fruits and vegetables for insects/Herbs and spices for sanitation control (1986) Pork for Trichina parasite (1997) Fresh and frozen meats to reduce pathogens (2000) Spinach and lettuce to reduce pathogens (2008)

What is happening at the cold point?

Zone of the slowest heating

How can pH's be decreased? What type of processing is used with pH's greater than 4.6? Less than 4.6?

pH can be decreased by fermentation or acidification. Products with a pH less than 4.6 should be processed with boiling water, and greater than 4.6 should be processed under pressure.