PH meter for meat monitoring and testing - Project report on quality meat with the help of a pH meter
PH meter for meat monitoring – DIY
Monitoring of meat using a smart pH meter. This
project is presented in the following order:
· Introduction
·
Related literature
·
Components required
·
Blog diagram
·
Principle of operation
·
Circuit diagram
I.
Introduction
Application:
Cold room for monitoring meat to be fit for consumption
The world’s
population and that of Cameroon is rapidly increasing and we all know that
one of the problems faced, is inadequate supply of food. Meat is
one of the most important foods and in some countries it is considered as an essential
product with very high consumption rates. In our traditional society, meat
(pork, chicken, beef and others) whether fresh or in dry form is an integral
part of most meals in homes and restaurants. The quality of these products is
of great importance since quality meat is an essential source of nutrients such
as: protein, fatty acids, vitamins, minerals and other bioactive compounds which
are very important for good health of most of its consumers.
II.
Related literature
The pH value is a
widely used way of expressing the acidity or alkalinity of all sorts of
products especially in food and is widely used in food processing industry.
PH: pH
with full meaning, “pondus hydrogenii (power of hydrogen)” expresses the very
small concentrations of hydrogen ions, a measure of alkalinity or acidity of a
solution. It was proposed in 1901 by a Danish scientist Soren Peter Lauritz Sorensen.
In
1909 Soren Peter Lauritz Sorensen defined PH as the negative base 10 logarithm
of the hydrogen ion activity and derived the equation for calculating the PH.
Where
log stands logarithm in base 10 and [H+] stands for the hydrogen ion concentration with
units moles per litre.
PH meter
A
pH meter is an electrochemical device capable of measuring pH values of acidic
and alkaline solutions or samples. The pH is measured on a pH scale of 0 to 14 with
a pH of 7 being neutral. A pH less than 7 (pH < 7) is acidic and a pH
greater than 7 (pH > 7) is basic or alkaline. Since the pH is measured on a
logarithmic scale, the pH value of successive whole number less than 7 is 10
times more acidic than the next one and above 7 it is 10 times more basic than
the preceding one.
The
meter consists of a pH proton-sensitive electrode usually made of glass and a
reference electrode (usually made of silver chloride or calomel) and the
electronics of the meter itself.
The
figure below shows the pH measurement cell.
Figure 1. A general
view of a pH measurement cell
PH
of muscle tissue, meat and effects
The
pH of muscle tissue is extremely important to meat science since the pH at
specific times during the conversion of muscle to meat, as well as the ultimate
pH of meat, affects many quality factors.
The ultimate pH is determined by the extent of the pH
decline at 24 hours after slaughter. The variation in ultimate pH influences
factors such as color and the water retention level of the meat. A low ultimate
pH results in meat proteins having decreased water-holding capacity and a
lighter color. Conversely, a higher ultimate pH will give a darker color and
less drip loss. Other factors include grading characteristics
and shrink of carcasses, texture, tenderness, juiciness, taste, appearance.
In
a normal living muscle the pH is approximately 7.1-7.2. After slaughtering of
the living muscle, some of the glycogen is broken down into lactic acid. Hence,
the pH value is lowered. The acidity depends on the type of breed, rearing
characteristics and treatment of the animal prior to slaughter. The pH can range from 5.2 to 7.0 with the highest quality
in the pH range of 5.7 to 6.0. For example, beef normally reaches
its lowest pH value of 5.4 to 5.7 at 18-24 hours after slaughter. After the
lowest pH level is reached, the pH starts to rise again slowly but steadily. By
the time it reaches pH of 6.5, it starts to decompose. Pork already reaches its
lowest pH value of 5.4 to 5.8 at 6-10 hours after slaughter.
Effects
of temperature on pH Measurement
Temperature affects pH
measurement in two different ways. The first impact of temperature is on the pH
electrode itself. It changes its response as temperature also changes. At
higher temperatures, they respond more strongly to pH changes. At 100 ºC, they
change their output potential by 74 mV/pH unit, and at 0 ºC, they change by 54
mv/pH unit. Because pH meters are typically standardized at pH 7 (that is, zero
mv = pH 7), the error from temperature differences gets greater and greater as
the pH being measured gets further from 7. So it may be trivial when measuring
something with a pH of 7.1, but very important when measuring something with a
pH of 10 (or when calibrating with a pH 10 buffer).
Secondly, temperature
affects the solution under measurement due to some chemical changes. For
example acids can, become stronger or weaker with change in temperature. If the
solution is in contact with solids, the temperature can also impact the amount
of acid or base is the solution thereby impacting the PH. These effects are
specific for every solution you will encounter.
III.
Components required
·
PIC 16F876A
·
LCD 16X2
·
9V Battery
·
Regulator LM7805
·
Capacitors 1nF(3), 22pF(2)
·
Switch
·
Resistors 10k Ω,470Ω(3), 220Ω
·
Transistor BC547
·
OPAM LM358
·
Analog pH/Moisture sensor
·
5V block relay
·
Temperature sensor DS18B20
·
5kΩ variable resistor
·
Oscillator
IV.
Blog diagram of a pH meter for cold room meat
monitoring
Figure 2: Block diagram of the PH meter
V.
Principle of operation
To
monitor the meat in a cold room in order to obtain quality meat, the Analog pH/moisture
sensor is placed in contact with the meat, the sensor is coupled to an OPAM
with the used of a relay which toggles in order to measure the analog values of
pH and the moisture of the meat. These analog values are sent to the ADC of the
PIC microcontroller which processes the information and displays the corresponding
digital values on the LCD. The temperature sensor is also used to monitor the
temperature of the meat and displayed on the LCD. LEDs are used to warn if the
temperature, pH/Moisture are in or out of range. Hence need for adjustment.
For
good storage temperature generally <7oC are acceptable and
quality meat should fall within the range:
VI.
Circuit diagram
Simulation
of complete diagram with proteus
The complete circuit is shown in the figures below.
Figure 3: complete circuit diagram of the pH meter for meat
testing
The first LED1 (D3) indicates the presence of power. LED2 (D4)
indicates normal conditions (values are in range). LED3 (D5) is used to indicate
abnormal conditions ( the pH/moisture and or the temperature is out of range) ,
hence need for adjustment.
The simulation of the circuit is shown in the figures below.
Figure 4: Values in range (normal conditions)
The values of the pH,
moisture, and temperature are 6.19, 85.60% and 03.750 respectively,
which fall within the acceptable range of:
The LED (D4) shines
indicating normal conditions.
Figure 5: values out of range (abnormal)
The values of the pH,
moisture, and temperature are 4.8, 52.40% and 14.930C respectively,
which out of the acceptable range of:
Hence, the LED (D5)
shines indicating abnormal conditions. Hence the quality of the meat is not
accebtable.
PCB and complete realized circuit
Figure 6. Complete pH
meter for meat monitoring
This project can be
modified to suit your design contact EKETECH. This can also be modified to suit
various applications like in homes, local meat vendor’s areas etc.
Reference:
Angong
A.N. (2019), pH
meter for meat monitoring.
Ek
electrical technologies-All about circuits and designs (2019), pH meter for meat
monitoring, https://eketechcamer.blogspot.com