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List 3 reasons for processing foods. - ANSWER-increase the shelf life ensure food safety inhibit spoilage What are the five major objectives of processing? - ANSWER-flavor convenience enrichment minimize nutrient loss variety (FCEMV) Restoration - ANSWER-Addition to restore nutrients lost in processing Fortification - ANSWER-Addition to make a good source of that nutrient. Ex. Vitamin C added to "High-C" fruit drink. Ex. Vitamins and minerals added to breakfast cereals. Enrichment - ANSWER-Addition of a specific nutrient by government mandate to alleviate a public health issue Ex. Flour (bread, pasta, cookies) - niacin (prevent pellagra), thiamine (B1), Riboflavin (B2), iron and folic acid. Ex. Salt - Iodine added to prevent goiter. Ex. Salt - Iodine added to prevent goiter. What so special about a plate heat exchanger? What types of foods is it used with? - ANSWER-โ plate heat exchanger uses stainless steel plates (SS is inert) get rid of pathogens pumps the liquid product (i.e. milk, Capri Sun, etc.) into two sections of plates 1st section: heat section using steam to heat up liquid (the plate gets hot from the steam and then liquid gets hot from the plate) โ liquid is pumped into cold section 2nd section: cold section where Freon is used to cool it down
one determines time going to raise temperature by how fast one pumps the milk through and how many plates are present How does an extruder work? How does it differ from a grinder? - ANSWER-โ extruder pumps steam into a barrel when it comes out the end, all the steam escapes (there is no more pressure) different from grinder because it uses high pressure and steam used to make Cheetohs and hot dogs* How do indirect unit operations differ from direct? - ANSWER-โ indirect: comes after monitoring regulating How do direct unit operations differ from indirect? - ANSWER-โ direct: happens during the process of making the food What are the five major functions of a food package? - ANSWER-1. Convenience
- Protection
- Labeling
- Portion control
- Advertising and selling package advantages - ANSWER-1 Convenience Facilitate handling 2 Protection Physical Damage Contamination Insects Rodents Microorganisms Oxygen Moisture Odors Flavors Light 3 Labeling
โ Plastic can't tolerate a lot of heat, melts easily Why is the oxygen scavenger package so special? - ANSWER-โ Oxygen causes rancidity with foods; oxygen scavenger package delays rancidity There are 2 layers of surlyn w Palladium Catalyst in between Surly allows gases to pas through it but not liquids, traps oxygen to avoid rancidity, used with salmon What are the layers of the oxygen scavenger package? - ANSWER-โ consisted of layers 1st flushed with hydrogen and nitrogen (inert) gases 2 layers of surly allow gases but not liquids to pass through palladium catalyst produces 2 molecules of H20 when it comes in contact with hydrogen and oxygen gases liquid then gets trapped in layers by foil because no liquid or gas gets beyond the foil In the USA, what are the three most consumed food additives by weight? - ANSWER-1. Sugar
- Salt
- High fructose corn syrup What are the four kinds of heat transfer we discussed in class - ANSWER-1. Conduction - Direct contact with source Agitating molecules give up energy to slower molecules until food is heated throughout Slowest method of heat transfer *Ex. Spoon in pot of hot soup - handle heated by conduction
- Convection - Transfer by currents in flowing matter (liquids and gases) Heated material becomes less dense and rises. Sets up currents. Faster than conduction
- Radiation - Transfer of heat by emission of waves Will heat surface only, then heat penetrates the food by conduction or convection Faster heating than convection *Ex. A charcoal grill
- Microwave Fastest method of the four
How does a microwave oven work? What "cool" science is involved?
- ANSWER-โ Reflection: Microwave energy is reflected from metals, metals do not heat. โ Transmission: Some elements like glass let waves pass through without heating. โ Absorption: Those materials which absorb microwaves are heated. Foods rank high as microwave absorbers. Microwave absorbers have to be polar molecules (like water) โ Electromagnetic waves go through oven changes magnetic field and causes polar molecules to move (creating heat) โ Metal mesh on glass protects us from the microwaves Is a microwave oven's heat penetration from the inside out? - ANSWER-โ no from outside-in Advantages of microwave - ANSWER-Penetration - faster thawing and cooking Less nutrient loss Less energy costs Disadvantages of microwave - ANSWER-No Browning Safety issues Metal arching Pace makers Steam pressure in sealed foods Cold spots What are the basic parts of a refrigerator and how does it work? - ANSWER-โ Liquid-liquid reservoir: high-pressure liquid โ Expansion valve: releases high-pressure liquid freon turns from liquid to gas inside of the refrigerator because of the temperature change [it's 40 degrees in fridge] flow of the liquid is controlled and pressure is lowered so that some of the liquid turns into a vapor evaporation cools the remaining liquid โ Evaporator coils: Low-pressure gas, evaporation cold liquid absorbs heat from the air in the fridge, chilling the inside of the fridge, the liquid vaporizes โ Compressor pump: High-pressure gas vapor is compressed, bringing it to a higher temperature
sufficient alone or in combination with other ingredients and/or treatments render the product free of pathogenic microorganisms. โ Complete Sterility condition achieved by the application of: heat chemicals irradiation high pressure filtration to eliminate all forms of life including transmissible agents* What's a retort and why do we use it for canning foods? - ANSWER-โ retort pressure cooker used to reach temperatures over 100 Degrees Celsius temperature that sterilization occurs (116c- 130c) How does a hydrostatic retort work and what is so special about it (common sense and good science)? - ANSWER-โ hydrostatic retort essential principle = use of hydrostatic columns of water to counterbalance pressure of steam used in the sterilization zone process goes:
- cans are transported on long horizontal carrier bars
- bars enter the preheat leg at the top and progress down until they reach the steam chamber
- once in the steam chamber they make multiple rotations before emerging upwards through the cooling leg useful for processing products that: require long cook and cool times high throughputs and for those deriving limited benefit from agitation solves the problem of low productivity of batch retort provides better temperature uniformity in packed products by moving the packages in heat transfer media What is aseptic packaging? - ANSWER-โ aseptic packaging food is sterilized by exposure to high heat for a few seconds package is sterilized separately from food with hot hydrogen peroxide and dried with sterile air sterile food dispensed into sterile packages the entire package takes place in a sterile environment
result is a shelf stable product with a long shelf life functions of the 7 layer aseptic package: - ANSWER-1. polyethylene (PE) - moisture barrier, product contact surface
- adhesive layer - bonds foil to PE
- aluminum foil - prevents volatile flavor compounds from escaping, keeps light and oxygen from intruding and reacting with the food
- polyethylene (PE) - Lamination layer between aluminum and paperboard
- paperboard - stiffness, strength, durability
- print - identification of contents and marketing
- polyethylene (PE) - moisture and contamination barrier What are the two basic reasons for cans to swell? - ANSWER-โ hydrogen swells release of hydrogen gas by the action of food acids on the iron of the can microbes producing gas types of Swollen Cans: - ANSWER-flipper - one end may become convex by striking springer - can with both ends bulged; one or both remain concave if pushed in, or when one is pushed in the other pops out soft swell - can with both ends bulged so that neither end can be dented by hand What does a normal drying curve for a food look like and why? - ANSWER-โ normal drying curve starts at high moisture content and immediately drops steeply at constant rate begins to level out to falling rate as time goes on What factors affected the rate of food drying? - ANSWER-1. Surface Area
- Air temperature
- Air Velocity
- Air Dryness โ In Food Itself:
- Constituent Orientation
- Cellular Structure
- Solute Concentration
- Binding of Water
- Shrinkage
- Food Porosity ***(drying can change the shape of the food product)
nutritious liberate nutrients synthesize nutrients What must be controlled in fermentation? - ANSWER-โ must be controlled acids levels of alcohols starter culture temperature level of oxygen salt Aw = water activity How do we make cheese? - ANSWER-โ Cheese (lactic acid fermentation): Milk โ pasteurized โ lactic acid "starter" culture added โ rennet โ milk coagulates โ cut and "cooked", curd and whey separated โ salted and pressed โ cheese โ aged or ripened How do we make wine? - ANSWER-โ Wine Gather grapes โ stemming and crushing (must) โ SO2 Destroy Wild Yeast โ Add yeast โ primary fermentation โ press wine out of skins โ secondary fermentation โ racking - to remove sediment (Lees) โ Aging How do we make beer? - ANSWER-โ Beer Malting germinate barley amylase Mashing 25% Malt + 75% Grain enzymes hydrolyze starch --- sugars Lautering and Sparging filter - separate juice out wort = yellow liquid hops = flower seeds (humulus lupulus) give bitterness preservative effect Cool then "Pitch" inoculate - saccharomyces cerevisiae
ferment Green Beer (9-10 days) clarify, mellow, carbonate, age (1-3 months) How do we make pickles? - ANSWER-โ Pickles Cucumbers in water โ ferment โ add salt (allow L.A. bacteria to grow) โ CHO - Lactic Acid(0.8 - 1.5%) โ "salt stock" (storage of cucumbers) โ to make pickles: "salt stock" - leaching โ Alum (firmness) + turmeric (improve color) sweet pickles - (vinegar, sugar, spices, relish) sour pickles - (vinegar, 2.5% acidity) dill pickles - (vinegar, dill herb, spice) How do we make sauerkraut? - ANSWER-โ Sauerkraut salt 2.25% lactic acid 1.5 - 2.0% sequential organisms leuconostoc mesenteroides lactobacillus cucumeris lactobacillus pentoaceticus How do we make olives? - ANSWER-โ Olives bitter element (oleuropein) green more bitter removed with 2% NaOH (LYE) washed brine (6-7% salt) fermentation 1.5% acid Green olives picked before ripe, black olives allowed to ripen on tree How do we make cured meats? - ANSWER-โ Meat Curing or Pickling method varies composition sodium chloride (salt) - 24% sodium nitrite - less than 0.1% sodium nitrate (banned) sugar - 2.5% smoking added flavor preservation by heat and surface drying
Codex Alimentarius Commission - ANSWER-collection of internationally recognized standards, codes of practice, guidelines and other recommendations relating to foods, food production and food safety. Its name is derived from the Codex Alimentarius 1/100th rule - ANSWER-at the maximum of the food additive you can only add 1/100th Latent heat of fusion - ANSWER-heat absorbed as a substance changes phase from liquid to solid, a process called fusion or solidification Latent heat of vaporization - ANSWER-heat absorbed when a substance changes phase from liquid to gas Freezing point depression - ANSWER-process in which adding a solute to a solvent decreases the freezing point of the solvent Freezer burn - ANSWER-condition that occurs when frozen food has been damaged by dehydration and oxidation, due to air reaching the food.[1] It is generally induced by substandard (non-airtight) packaging Blanching - ANSWER-cooking process wherein the food substance, usually a vegetable or fruit, is plunged into boiling water, removed after a brief, timed interval, and finally plunged into iced water or placed under cold running water (shocking or refreshing[1]) to halt the cooking process Drip loss - ANSWER-loss in weight of food products owing to extruding and dripping away of tissue juices, such as meat juices lost during the thawing of frozen meat Super cooling - ANSWER-process of lowering the temperature of a liquid or a gas below its freezing point without it becoming a solid Nucleation - ANSWER-first step in the formation of either a new thermodynamic phase or a new structure via self-assembly or self-organisation. Nucleation is typically defined to be the process that determines how long an observer has to wait before the new phase or self-organised structure appears IQF - ANSWER-Fluidized-bed freezer -individually quick frozen Clarance Birdye (items moving around so they can freeze equally)
Must - ANSWER-freshly crushed fruit juice (usually grape juice) that contains the skins, seeds, and stems of the fruit. The solid portion of the must is called pomace. High Pressure Processing - ANSWER-Applies high pressure to solid or liquid foods to improve their safety and in some cases, organoleptic properties and quality Benefits of HPP includes: - ANSWER-Control of pathogens and spoilage Minimal processing w/o heat Preserve fresh food quality w/o additives Shelf-life extension Enzyme destruction Nutritional properties maintained Decreased processing time, energy use and waste Pulsed Electric Field Processing - ANSWER-high voltage pulses are applied to food held between 2 electrodes for a short treatment time Microbes and enzymes are inactivated through electroporation Ideal foods for PEF: - ANSWER-Liquid foods with small particles Foods high in acid and have low electrical conductivity For Example: fruit and vegetable juices, liquid egg and dairy products Advantages of PEF: - ANSWER-Kills live (vegetative) microorganismsInactivates enzymes Vitamins are unaffected Sensory characteristics are maintained (e.g. color) electroporation Cabinet Dryer - ANSWER-Fruits and Vegetables Concurrent and Countercurrent Tunnel Dryers - ANSWER-Fruits and Vegetables; plums to prunes Drum Dryer & Spray Dryer - ANSWER-Liquid Products Freeze Dryer & Continuous Vacuum - ANSWER-Variety Fluidized Bed Dryer - ANSWER-Vegetables
