Food Biotechnology

1. BY
ASSIST. PROF. Dr. BERCIYAL GOLDA. P

2. CONTENTS
Introduction
Importance
Sorption Isotherms
Measurements of Sorption Isotherms
Gravimetric Method
Manometric Method
Hygrometric Method

3. Sorption is a physical and chemical process by which one substance
becomes attached to another.
Sorption includes both adsorption & absorption
e.g., liquids being absorbed by a solid or gases being absorbed by
a liquid, cotton dipped in ink.
Sorption the process in which one substance takes up or holds another;
adsorption or absorption
Sorption is a process in which a solute moves from a fluid to
a particulate solid.
The food sorption isotherm describes the thermodynamic relationship
between water activity and the equilibrium of the moisture content of
a food product at constant temperature and pressure. ...
The typical shape of an isotherm reflects the way in which the water binds
the system.
INTRODUCTION

4. The sorption of volatile liquids on materials such as paper
toweling actually increases the volatility over that of the liquid itself.
Adsorption and absorption are two types of sorption phenomena.
Adsorption
Adsorption is defined as the deposition of molecular species onto
the surface. The molecular species that gets adsorbed on the surface
is known as adsorbate and the surface on which adsorption occurs is
known as adsorbent. Common examples of adsorbents are clay, silica
gel, colloids, metals etc
Absorption
Absorption is a condition in which something takes in another
substance. It is a physical or chemical phenomenon or process, in
which atoms, molecules, or ions enter in the inner part (called "bulk")
of a gas, liquid, or solid material.
Definition
Sorption is a physical and chemical process by which one
substance becomes attached to another. Specific cases of sorption
are treated in the following articles: Absorption

8. Gravimetric analysis is a quantitative determination of
the amount of analyte through a precipitation process,
precipitate isolation, and determination of isolated product
weight.
Gravimetry = analytical methods that measure the mass or
mass changes.
Using an analytical balance

9. TYPES OF GRAVIMETRIC METHODS
A. PRECIPITATION GRAVIMETRY
Appearance of insoluble compounds in a solution
containing our analyte when a precipitating
reagent/precipitant is added. The precipitate is then: filtered
and washed (impurities removal) converted to a product
(known composition) weighed.
A gravimetric method in which the signal is the mass of
a precipitate is called precipitation gravimetry.

11. B. Electrogravimetry
A gravimetric method in which the signal is the mass of an electrodeposit on the
cathode or anode in an electrochemical cell.
Aqueous ion: determination of Pb2+ by oxidizes to PbO2 and deposited on Pt anode
(chemicalconverting)

12. C. Volatilizationgravimetry
A gravimetric method in which the loss of a volatile
species gives rise to the signal (remove the volatile species)
Moisture: determination of water in food content by
heat or thermal or chemical energy (heating)

13. D. Particulate gravimetry
A gravimetric method in which the mass of a
particulate analyte is determined following its separation
from its matrix Suspended solid: determination of solid that
can be separated from the sample (filtration or extraction)

15. STEPS IN GRAVIMETRIC ANALYSIS
Gravimetric Analysis
1. Dissolve a sample after weighing.
2. A precipitating agent with excess amount
is added to this solution.
3. The resulting precipitate is filtered, dried
(or ignited) and weighed.
4. Determine the amount of the original ion
from the mass of the precipitate (known
composition).
5. Stoichiometry is important (write down
the chemical equation!).
Sampledissolution
Precipitation
Digestion
Filtration& washingof
precipitate
Dryingof precipitate
Weighingof precipitate
Datacalculations

16. Manometry technique of measuring the pressure
variation due to gas production/consumption caused by
biochemical reactions or physical changes
Applicable to any bioprocess implying the
production/consumption of a poorly soluble gas.
Main applications:
aerobic processes (oxygen consumption)
anoxic processes (N2 production)
anaerobic processes (biogas production)

18. Hygrometric methods are based on equilibrium
relative humidity (ERH) instead of moisture content.
ERH is numerically equal to water activity but
expressed as a percentage of the actual amount of water in
the air versus the amount of water the air could hold at
saturation
A hygrometer is an instrument used to measure the
amount of water vapor in air, in soil, or in confined spaces.
Humidity measurement instruments usually rely on
measurements of some other quantities such as
temperature, pressure, mass, a mechanical or electrical
change in a substance as moisture is absorbed. By
calibration and calculation, these measured quantities can
lead to a measurement of humidity.

23. THANK YOU