Part #2 Flashcards
What is food processing vs food preservation?
Food processing
- Conversion of raw animal and plant tissue into forms that are convenient and practical to consume
- All the operations from field and farm to consumer
Food Preservation
- Use of specific thermal and non-thermal techniques to minimize the number of spoilage and pathogenic microorganisms in foods, making them safe and extending the shelf life.
How many unit operations are there in food processing?
12
What are the 12 unit operations?
- Materials and handling
- Separating
- Cleaning
- Disintegrating
- Pumping
- Mixing
- Heat exchange
- Evaporation
- Drying
- Forming
- Packing
- Non-thermal methods
What are the three types of food deterioration?
- Physical - Handling
- Chemical - Enzymatic reactions
- Biological - Microbial growth
What are the three types of food deterioration?
- Physical - Handling
- Chemical - Enzymatic reactions
- Biological - Microbial growth
What are the major causes of food deterioration?
- Growth and activity of microorganisms
- Activity of endogenous food enzymes and other chemical reactions
- Infestation by insects, parasites and rodents
- Inappropriate temperatures
- Gain or loss of moisture
- Oxidation
- Exposure to light
- Physical stress
- Time
What are the major causes of food deterioration?
- Growth and activity of microorganisms
- Activity of endogenous food enzymes and other chemical reactions
- Infestation by insects, parasites and rodents
- Inappropriate temperatures
- Gain or loss of moisture
- Oxidation
- Exposure to light
- Physical stress
- Time
What is fermentation in food preservation?
Desirable microbial growth in food lead to certain chemical and physical changes so that the food can be stored for a longer period of time without deterioration
What are the two new food processing technologies we covered?
- Non-thermal: Irradiation, high-pressure, pulse electric field, ultrasonic waves
- Novel thermal process: microwave and ohmic heating
What are the three basic mechanisms by which heat is transferred?
- Conduction: Solid-Solid
- Convection: Fluid-Fluid
- Radiation:
What is lost during cooking?
- Lysine bioavailability reduced
- Heat sensitive vitamins (A and D)
- Water soluble vitamins (Thiamine, niacin, folate)
What is the primary objective of blanching?
- Inactivating deteriorative enzymes
- (minor) kills some spoilage bacteria
What deteriorative enzymes are inactivated in blanching?
- Lipoxygenase (LOX): Catalyze peroxidation of unsaturated fatty acids
- Polyphenol oxidase (PPO): Responsible for enzymatic browning
- Pectinase: Breaks down pectin. Tomato past would loose its thickness if not head treated immediately. (Hot Break process)
What nutrients are lost during blanching?
- Ascorbic acid
What are the two pasteurization processes?
- LTH (low temp, hold) 63C for 30min. This is more detrimental to nutritional and sensory properties.
- HTST (high temp, short time or flash) 72C for 15sec
What pH does Clostridium botulinum grow at?
4.6 or greater
What is the D value?
The number of minutes required at a particular temperature and in a particular medium to destroy 90% of the microorganisms in the population.
- Or to decrease the population by one log cycle.
What are the bulk effects of thermal processing on food constituents?
- Acid and salter accelerated destruction of microorganisms
- Protein denaturation
- Generation of cooked flavor due to reaction of sulfur from amino acid cysteine
- Maillard Browning reaction between reducing sugars and proteins (loss of nutrients)
- Loss of heat sensitive vitamins
What temperature is considered to be freezing storage?
-18C to -30C
What are the three distinct stages of a freezing process?
- Removal of sensible heat until freezing temperature
- Removal of latent heat of fusion leading to ice formation
- Further removal of sensible heat towards storage temperature
What is the continual decline of freeing point in foods?
However, as the solution freezes, pure water freezes
out preferentially. Therefore, the unfrozen region becomes more and
more concentrated with solute and exhibits further
depression in the freezing point – leading to a
continual decline in freezing point
What determines the size of ice crystal?
Rate of freezing (slow freezing leads to the formation of a limited number of ice crystals meaning large crystals but few)
- In frozen vegetables, ice crystals first form between the cells as they have lower concentration of solutes there.
What are the effects of slow freezing?
- Large ice crystals damage cellular structure of
frozen vegetables and lead to loss of structural
integrity - Formation of large crystals in inter-cellular
region of vegetables pulls water out of the cell
(due to osmotic equilibrium) - results in cellular dehydration - On thawing the cells unable to maintain rigidity
due to dehydration and disruption of cell wall by
ice crystals – leading to soft, flaccid texture and
loss of water
What are the effects of rapid freezing?
• Rapid freezing results in higher ice crystal
nucleation rate which lead to formation of
numerous small ice crystals both outside and
inside the cells of frozen vegetables
• Cells maintain their rigidity and minimizes drip
loss of water during thawing of frozen vegetables
• However, disruptive effect of size of ice crystals is
minimum in fish or meat (muscle food) due to the
elasticity of the cellular structure in muscles
– The mechanism of loss of quality due to slow freezing
of muscle foods is different than fruits and vegetables
What happens to protein when freezing?
denaturation bitch
What are the microbiological aspects of food freezing?
- Freezing does not significantly kill microorganisms already present in food
- Growth is reduced and a gradual decrease in their number can be observed
- However often there can be sufficient survivors that can multiple and give problem during the thawing process
How to prevent freezer burn?
- Humidity in freezer should be kept above 90%
- Glazing of food prior to freezing
What is IQF?
Individual Quick Freeze: Foods frozen individually
What is the time lag between harvest and consumption of non-climacteric and climacteric fruits?
- Non-climacteric fruits are harvested in fully ripened state and consumed quickly.
- Climacteric fruits are harvested immature so that they may ripen by the time of consumption.
What is senescence in fruit development?
Deteriorative process caused by aging, tissue death and associated with loss of quality.
What is Ethylene?
It is a plant hormone that plays key role in ripening and senescence of fruits and vegetables. All plants produce low level of ethylene, but any external stress can stimulate ethylene synthesis and release.
What are the effects of ethylene on fruit and vegtables?
- Chlorophyll is broken down, new pigments surface.
- Acids are broken down
- Amylase turns starch to sugar
- Pectin breaks down
- Breakdown of large organic molecules to produce aroma and tastes we associate with ripe fruit.
Do climacteric or non-climacteric fruit produce high levels of ethylene?
Climacteric fruit produce high level of ethylene during ripening. Non-climacteric fruit do not produce ethylene during ripening process but respond to exogenous ethylene by softening and increasing respiration rate (Ethylene can be used as a de-greening agent).
What happens to climacteric fruit during ripening (respiration)?
It increases and heats up.
What fruit pH is at highest risk for bacterial infections?
Higher pH can.
What is the most important cause of loss in fresh produce?
Physical injuries. This stimulates ethylene production
What is precooling?
Removal of field heat as quickly as possible after harvest is essential for slowing down the rate of deterioration of highly perishable products.
Where does primary and secondary packaging site in respect to food?
- Primary: in direct contact
- Secondary: material may also be used for convenience and protective purpose and for printed material
What are the recycling plastics coding system?
- # 1 PETE or PET: Polyethylene terephthalate
- # 2 HDPE: High density polyethylene
- # 3 PVC: Polyvinyl chloride
- # 4 LDPE: Low density PE
- # 5 PP: Polypropylene
- # 6 PS: Polystyrene
- # 7 Other: Mixed plastics and bioplastics
What is modified atmosphere packaging?
MAP is the introduction of an atmosphere, other than air, into a food packaging without further modification or control.
What is molecular gastronomy?
It is the scientific discipline that studies that physicochemical transformation of edible materials during cooking and the sensory phenomena associated with eating them.
What is gastronomy?
Defined as “Intelligent knowledge of whatever concerns nourishment of man”. Gastronomy is not cooking, cooking is the process of preparing dishes.
What are the objectives of molecular gastronomy?
- Modeling culinary dishes
- Collect and test “culinary precisions”
- Explore the art component of culinary activities
- Explore the “Social link” of culinary activities
What is note-by-note cuisine?
Making dishes entirely from molecular level using dispersed system formula.
What is molecular cuisine?
Producing food in kitchen using new tools, ingredients and methods
What is molecular cuisine?
Producing food in kitchen using new tools, ingredients and methods
What is anosmia?
The lack or lost ability to smell.
What is tronasal olfaction?
The detection of an odorant when it is released from food in your mouth during chewing, exhalation, or swallowing.
What is othonasal olfaction?
The detection of an odor through the nostrils by sniffing or inhalation.
What does the trigeminal nerves?
They are responsible for sensation in the face and controlling how we chew and bite food.
What are supertasters?
- Have strong dislikes
- Can detect specific ingredients in food samples
- It is through that supertasters are the people with a greater number of fungiform papillae
What is a triangle test?
Two samples same third is different
What is paired comparison test?
Two samples side by side
What is the hedonic scaling?
Nine-point scale
