Midterm

Question 1

Pasteurization name came from

Answer 1

Louis pasteur

Question 2

Louis studied

Answer 2

the
application of heat in controlling fermentations and preserving
the liquid product.

Question 3

Napolenic wars was in the years

Answer 3

1799-1815

Question 4

Napoleanic war detail

Answer 4

Supply lines were stretched and army was hungry so napoelin offered a prize of 12,000 francs for a new method to perserve and the winner was nicholas appert

Question 5

Nicholas appert

Answer 5

Nicholas appert from the year 1749-1841 publishes article on perserving food and found that foods heated in sealed
containers would not spoil as long as the containers remained closed and created product heated in sealed glass bottles He called this appertization and wrapped the bootles in canvas

Question 6

In 1810 who developed tin cans

Answer 6

Peter durand

Question 7

Can opener made by

Answer 7

Yates in 1855

Question 8

Who disovered before apperts did

Answer 8

Lazzaro Spallanzini shows meat extract perserved in sealed glass by boilling for one hour and carl wilhelm scheele used vinegar to perseve in 1782

Question 9

French wine disaster

Answer 9

early 1860’s, the French wine
industry was on the verge of
collapsing due to unknown and
unwanted contaminants. severe impact on export
of wines.Louis Pasteur (1822-1895) was requested by Emperor
Napoleon III to investigate Pasteur identified the source of the
problem as being “microbes” that
could be killed by heating to about
60⁰C.
* Pasteur also applied the process to
beer –but not to milk!
* Process became known as
“Pasteurization”

Question 10

Pasteurizatin before pasteur

Answer 10

William Dewees, - milk be
heated to near boiling and cooled prior to using the milk for
babies. tendency of milk to decompose
in hot weather was diminished
by this treatment

Question 11

20th Century, many
people felt that pasteurization of milk
was

Answer 11

undesirable and unnecessary

Question 12

In 1908, became the first city in the world to
require pasteurization of milk sold within the city limits.

Answer 12

Chicago

Question 13

Selling raw milk

Answer 13

Sales of raw milk flourished just outside city limits.
 In 1909, legislation was passed by City of Chicago that
addressed this problem.

Question 14

first commercial milk pasteurizer

Answer 14

In 1881, the first commercial milk pasteurizer was
introduced in Germany.

Question 15

Dr. Henry
Koplik.

Answer 15

In 1889, the world’s first dispensary of heat-treated milk for
infants was established in New York City

Question 16

1923, APV developed

Answer 16

plate heat exchangers which
enhanced control over the pasteurization process.

Question 17

n order to determine if milk has been effectively pasteurized,
_ is used as an indicator.

Answer 17

alkaline phosphatase

Question 18

alkaline phosphatase

Answer 18

responds to time-temperature exposure in such a
way that it can be used to monitor the degree of pasteurization
that a particular batch of milk has had. f the residual enzyme concentration is above a specified value,
the degree of pasteurization has been insufficient to meet
processing requirements

Question 19

test for alkaline
phosphatase activity,

Answer 19

specific assay is performed,
often involving a color
change that indicates
enzyme activity. If the
enzyme is present, the milk
may require further heat
treatment. A substrate solution (often p-nitrophenyl phosphate) is added
to the milk sample. This substrate is colorless and becomes
yellow when dephosphorylated by alkaline phosphatase.
After incubation, the reaction is halted, often by adding an alkaline
solution. The intensity of the yellow color developed is measured
using a spectrophotometer at a specific wavelength (typically
around 410 nm).

Question 20

Specific Heat:

Answer 20

 This is the amount of heat lost or gained in changing the
temperature of a unit mass of product by one

Question 21

Sensible Heat

Answer 21

When heat is added to or removed from a material and a
temperature change results, this is called “sensible heat”.
* It can be felt or sensed by
touching the material
* The change in temperature
can be measured with a
thermometer.

Question 22

Latent Heat:

Answer 22

When heat is added to or removed from a material and
causes a change in state (e.g., from a liquid to a solid, or a
solid to a liquid) without causing a change in temperature,
this is called “latent heat”.
* Since there is no observable temperature change, this
heat is essentially “hidden”

Question 23

Latent Heat of Fusion:

Answer 23

The amount of heat removed or added to a unit mass
of material to change its state from a liquid to a solid or
vice versa with no corresponding temperature change.

Question 24

Latent Heat of Vaporization

Answer 24

The amount of heat required per unit mass of liquid to
change it to a gaseous state with no corresponding
temperature change.
 The units are kJ/kg.
 Note: The reverse of the latent heat of vaporization is
the latent heat of condensation.

Question 25

latent heat of fusion for one kg of apples

Answer 25

it follows that
the latent heat of fusion for one kg of apples is 84% of the
latent heat of 1 kg of pure water.
Remember: This is because apples contain 84% water.

Question 26

The following factors will influence microbial growth in heat treated
canned products 5

Answer 26

the species of microorganisms in the microbial population
 acidity of the product
 ability of the population to grow in anaerobic environments
 water activity of the product (lower aw’s protect spores)
 thermal resistance of the food itself

Question 27

Process Lethality

Answer 27

A typical “sterilization”
process is designed to
provide a suitable time at a
specific temperature for the
coldest particle or volume
element of product in a
package or processing
stream.

Question 28

Slowest heating region or container cold
spot depends on the:

Answer 28

Type of product
* Container type and size
* Thermal processing method/system
* Heat transfer mechanism

Question 29

lethal
temperature.

Answer 29

The temperature which is being targeted to “kill” the
microorganisms that are present 121°C (or 250°F)

Question 30

unit of lethality”

Answer 30

the amount of heat
kill equivalent to one minute at 121°C for a microorganism
with a given z-value.

Question 31

Heat equation

Answer 31

Q=mcpT

Question 32

Membrane Filtration

Answer 32

using a
semipermeable material as
an interface to separate
solutes.

Question 33

Feed

Answer 33

he solution that
enters the system
containing molecules
(of diverse
characteristics) in a
solvent, usually water.

Question 34

Permeate

Answer 34

the liquid and the
molecules it contains that
pass through the
membrane.

Question 35

Retentate

Answer 35

the liquid and solutes
that do not pass through
the membrane.

Question 36

Flux rate

Answer 36

used to
describe the rate at which
permeate goes through the
membrane.
It is expressed in units of
volume per membrane area
per unit of time

Question 37

Tangential flow

Answer 37

flow pattern
most often used in membrane
processes where the feed is passed
across the membrane surface rather
than straight down upon it.
In this way, the flow continuously
sweeps across the membrane surface
and carries away much of the material
that might otherwise foul or plug the
membrane and its pores.

Question 38

Dead-end Filtration

Answer 38

Fluid flows
perpendicular to the membrane.
It has a simple setup, ideal for low
particle loads (e.g., water purification,
lab filtration).
It is encountered mainly at the lab scale
for analytical purposes.

Question 39

Dead-end Filtration Why Dead End?

Answer 39

Particles accumulate on the surface,
forming a filter cake.
*Requires frequent cleaning or
replacement.

Question 40

Pressure-driven
membrane
technologies common basis

Answer 40

Particle size difference is
the common basis for
pressure-driven membrane
separation
* Other physicochemical
interactions (e.g.,
electrostatic, H-bond, π-π)
may play an important role,
especially for tight and
dense membrane
separations

Question 41

Pressure-driven
membrane
technologies types

Answer 41

Microfiltration, ultrafiltration, nanofiltration and hyperfiltration / reverse osmosis

Question 42

Microfiltration

Answer 42

0.1 - 10
μm
MF is commonly used to remove insoluble particles (typically
particles responsible for turbidity) and microorganisms such as
yeasts or bacteria

Question 43

Ultrafiltration

Answer 43

0.1 ~ 0.01
μm
It mainly addresses macromolecule separation. The molecular
weight cutoff is defined as the molar mass of the smallest molecule
rejected at 90%. UF (together with the MF) is also efficient for
colloids, a family of particles difficult to remove because of their
small size (1 μm-1 nm) and stability (electrical repulsion).

Question 44

Nanofiltration

Answer 44

0.01 ~
0.001 μm
A specificity of NF membranes is the presence of superficial charge
(also evidenced in the UF to a lesser extent). Depending on the pH
of the solution, lower or higher than the isoelectric point (pHi) of
the membrane, the membrane surface is either positive or
negative (3, pHi, 5)

Question 45

Hyperfiltration/
Reverse
Osmosis

Answer 45

0.001 ~
0.0001 μm
It is mainly based on the difference in solubility and diffusion of
water and solutes in the membrane material, favouring water
transfer compared with solute transfer.

Question 46

Membrane Structures

Answer 46

Symmetrical membranes like isotropic microporous and nonporous dense membrane
Anisotropic membranes like loeb-sourirajan anisotropic and thin fim composite anisotropic

Question 47

Electrodialysis

Answer 47

membrane
process that separates ions across
ion-selective membranes under an
electric field.

Question 48

Electrodeionization

Answer 48

continuous
technique of eliminating ionizable
species from feed water using
electrodialysis and ion exchange resins.

Question 49

What are the properties of the permeate in the ultrafiltration
process?

Answer 49

First, we will need to do a mass balance on the feed and
retentate solutions based on the information given.

Question 50

The water in an oil/water mixture is forced in centrifugation

Answer 50

outside of
the spinning centrifuge and the less dense oil forms a layer
on top of the water towards the inside of the spinning
centrifuge.
basket centrifuges (batch and continuous)
 perforated bowl centrifuges

Question 51

The benefits of freeze concentration include

Answer 51

lack of a
heat treatment step which can vapourize volatile flavour
components and aromatics.
* The heat may also cause other thermal damage to the
product.

Question 52

Freeze conc steps

Answer 52

step 1 filling of wash column, 2. compressing ice crystal, 3. washing crystal with water, 4. scarping ice from top

Question 53

Drying is done primarily through

Answer 53

Evaporation or sublimation

Question 54

We dry foods to

Answer 54

to achieve a desired moisture level
to reduce spoilage
to increase shelf life
to reduce weight (shipping etc.)
to enhance convenience
to alter inherent attributes
to facilitate further processin

Question 55

Mechanism to dry foods includes

Answer 55

Liquid Diffusion
* Vapour Diffusion
* Freeze Drying (Sublimation)
* Surface Diffusion
* Hydrostatic Pressure Difference
* Combination of these methods

Question 56

Factors influencing Drying

Answer 56

Product composition / structure
Thickness
Particle size
Particle shape (characteristic dimensions)
Porosity
Specific heat
Surface characteristics
Moisture content
Seasonal variation
type of dryer
-temperature of air
-relative humidity of air
volumetric rate of air flow
-linear velocity of air flow
direction of air flow
-retention times

Question 57

Possible negative factors of drying

Answer 57

Nutritional degradation:
Many vitamins are unstable and highly susceptible to heat
damage.
Loss of structural integrity:
Stresses in drying may cause cells or structural matrix to
collapse
Reduction in functionality:
* Changes in structure due to heating such as starch gelatinization.
* Protein Denaturation and Loss of Solubility
Flavour changes:
Caramelization due to browning or Maillard Reaction. This may
or may not be desirable.
Case hardening:
Excess surface drying creates impermeable outer “shell” that
prevents or restricts moisture loss.
Often, the product feels dry but it is only dry on the surface.
Leaching of soluble constituents:
Water draws soluble nutrients to the surface of the material as it
diffuses from the interior during drying.
These soluble nutrients can then be lost if the dried material is
placed in water to re-hydrate it.

Question 58

Plate Heat Exchanger ( Flow Diversion Valve)

Answer 58

Flow from heat exchanger
2.Flow of finished product
3.Diverted flow (if needed)
4.Piston to valve
5.Assembly to activate valve

Question 59

Thermal Processing Operation

Answer 59

Control panel with circular
recording chart.
2.Balance tank
3.Centrifugal pump
4.Plate heat exchanger
5.Frame of modular unit