FIELD OF THE INVENTION

The present invention relates to a refrigerator and more particularly to a refrigerator having a device for detection of different levels of food spoilage and indicating the shelf life of food commodities stored therein.

BACKGROUND OF THE INVENTION

Conventional frost free refrigerators have two thermally insulated compartments commonly referred to as freezing and refrigerating compartments. Some more recent refrigerators have a vegetable box covered by a crisper tray in the refrigerating compartment for storing various kinds of food products such as milk products, meat products, fruits, vegetables, processed food, etc. The different compartments are so designed to maintain the proper temperature according to the different types of food products stored in the refrigerator. The temperature in the freezing compartment is maintained below 0°C, while the temperature in the refrigerating compartment is around 0°C to 10°C. The temperature in the crisper tray is usually a few degrees higher than the rest of the refrigerating compartment.

Food products like vegetables and fruits are composed of organic compounds. The purpose of maintaining a low temperature inside a refrigerator is to lower the rate of decomposition of these organic compounds due to respiration and other biochemical reactions / changes. Thus, refrigeration keeps the food products fresh for a much longer time. However, in the event of frequent power failure or fluctuation in the voltage supply, the temperature inside the various food storage compartments increases above the preferred values. Prolonged exposure to high temperatures causes the food to get spoiled rapidly.

The conventional refrigerators do not have any system for detecting food spoilage, i.e. there is no device provided to indicate to the user whether the food is suitable for consumption or not. Thus, the user has to check for spoilage by visual inspection or using senses like touch or smell. Such manual examination isn't always accurate and sometimes the user consumes stale or spoiled foods. Normally people only realize that the food is dangerous for consumption when they can smell the foul odor of rotten or stale food. This is not a reliable way of judging food spoilage and bacteria can also be present even without any smell.

For instance methane released by degradation of certain food products is colorless and odorless, so the user can't observe its presence by smell or visual inspection. Consumption of spoiled food is harmful for health and could be a major source of food poisoning. In other cases, due to incorrect judgment the user may throw away food products which are still fit for consumption, which leads to unnecessary wastage.

Several prior arts have proposed some methods and devices to address this problem. One set of prior arts is based on predicting the freshness of the food items on the basis of the temperature inside the refrigerator and/or the age of the food items in comparison to their expiration date. Another set of prior arts use sensors to detect a gas released upon decomposition of certain types of foods. The sensor changes color based on the concentration of the gas and provides a visual indication to the user.

US Patent No. 7,372,003 pertains to "Systems and methods for monitoring conditions that affect the quality of food being served. Sensors such as temperature probes can provide temperature information about the container and/or the food being served. The monitoring system can use such information in conjunction with elapsed time information in various ways." This system is only able to provide a prediction because the time and temperature are only indicators of the deterioration that could be present, but they are not a means to measure the actual level of deterioration of the food products.

US Patent No. 7,495,558 discloses "A perishable integrity indicator system includes a RFID transponder and a perishable integrity sensor. The RFID transponder includes a RF integrated circuit coupled with an antenna. The sensor monitors the time and temperature of the perishable. A freshness determining module receives time and temperature dependent measurement data from the perishable integrity sensor and determines a current freshness status." This system also provides an alarm in case the food is unfit for consumption, but still suffers from the deficiencies pointed out in US Patent No. 7,372,003.

US Patent Application No. 13/317,228 discloses a bio-indicator insert which includes a porous substrate onto which a biosensor solution is applied, the biosensor solution being at least partially externally visible through the transparent cover. In use, the biosensor solution is adapted to change color within a defined color range that is dependent upon the concentration of amines detected. In this manner, the food quality indicator provides a visual indication of the state of microbial spoilage experienced by a food product in close proximity thereto. This method however does not provide an indication on the level of spoilage of the food item(s). Thus, the user will have to depend on his judgment to gauge the level of spoilage. The only definite indication is provided when the biosensor changes color completely, but the food is completely spoilt by this time.

Accordingly, it is an object of the invention to overcome the limitations set above in the prior arts. The invention aims to detect the freshness of the food items stored in a particular compartment on the basis of a quantitative analysis of the gases released upon degradation of the food, categorize the freshness of the compartment into different levels, provide the user with a visual indication of the level of freshness/spoilage, and alarm the user in case the food is unfit for consumption. An added advantage is that since food spoilage can be detected at an early stage, the spoilt items can be removed promptly so as to prevent the spoilage of the other stored food items.

SUMMARY OF THE INVENTION

In accordance with an embodiment of the invention, is provided a refrigerator comprising a freezing compartment and a refrigerating compartment; characterized in that, a food spoilage detecting device is provided for at least one location inside the refrigerator.

In accordance with another embodiment of the invention, is provided a refrigerator wherein the food spoilage detecting device comprises:

- a Sensor mounted inside the refrigerator for detecting the concentration of at least one of the gases released upon decomposition of the food;

- a plurality of Indicator means, each representing a spoilage level for the food items based on the concentration of the gases detected by the Sensor;

- a Microcontroller for controlling the other components of the food spoilage detecting device;

- a Linear Power Supply for supplying power to the components of the food spoilage detecting device.

In accordance with yet another embodiment of the invention is provided a refrigerator wherein the food spoilage detecting device further comprises:

- a Display Device connected to the output of the Microcontroller for displaying the value of the concentration of gases and/or input power being supplied to the refrigerator;

- a Control Switch for allowing the user to choose between displaying the concentration of gases or voltage of input power on the display device; and,

- a plurality of LED indicators for indicating whether the concentration of gases is being displayed or voltage of input power is being displayed on the display device.

In accordance with yet another embodiment of the invention is provided a refrigerator, wherein the Sensor is an air quality sensor. In a particular embodiment, the air quality sensor comprises a Sn02 sensitive layer, a micro Al203 ceramic tube, a measuring electrode and a heater.

In accordance with yet another embodiment of the invention, is provided a refrigerator wherein Indicator means are in the form of light and/or sound output devices like LEDs, bulbs, semi-conductor lighting sources, speakers, alarms, electronic voice output devices, etc. In a preferred embodiment, the Indicator means are in the form of a plurality of dissimilarly colored Light Emitting Diodes (LEDs).

In accordance with yet another embodiment of the invention, is provided a refrigerator wherein the

Indicator means comprises three LED indicators to indicate three levels of freshness of the food items stored in the compartment(s) where the Sensor(s) is/are provided; said LED indicators comprising:

a. a green colored LED to indicate that the food is fresh;

b. a yellow colored LED to indicate that the food should be consumed soon or removed from the refrigerator; and,

c. a red colored LED to indicate that the food is unfit for consumption.

In accordance with yet another embodiment of the invention is provided a refrigerator wherein the display device comprises a plurality of Seven Segment Displays. In an optional embodiment, the display device comprises a liquid crystal display, LED display, plasma display, etc.

In accordance with yet another embodiment of the invention is provided a refrigerator wherein the Linear Power Supply comprises:

a. a Step-down Transformer for stepping down an input supply;

b. a Bridge Rectifier for converting the stepped down power into DC (Direct Current);

c. a Voltage Regulator for converting the power from Bridge Rectifier into DC power of a particular voltage (say 5V); said particular voltage depending upon the operating voltage of the other components of
the food spoilage detecting device; and,

d. a plurality of electrolytic and/or ceramic capacitors.

In accordance with yet another embodiment of the invention, is provided a refrigerator wherein the refrigerating compartment comprises at least one crisper tray and at least one food spoilage detecting device for detecting food spoilage in the crisper tray.

In accordance with an embodiment of the invention, is provided a method of detecting food spoilage in a refrigerator having a food spoilage detecting device as disclosed in any of the above embodiments, comprising the steps of:

a. mounting the Sensor in at least one location inside the refrigerator;

b. detection of the concentration of the gases in the proximity of the Sensor using the change in the conductivity of a semiconductor layer (like Sn02), and giving an analog input to the Microcontroller from the same;

c. conversion of this analog input from the Sensor (300) into a digital output by the Microcontroller (100); the digital output representing the value of concentration of the gases;

d. comparing the gas concentration with pre-defined ranges that have been pre-programmed in the Microcontroller to determine the freshness level of the food; and,

e. sending output from the Microcontroller to the Indicator means for providing an indication of the freshness level to the user.

In accordance with another embodiment of the invention, is provided a method of detecting food spoilage, further comprising the steps of displaying the concentration value of the gases to the user by sending the digital output obtained in step (c) to the Display Device.

In accordance with yet another embodiment of the invention, is provided a method of detecting food spoilage, further comprising the steps of: conversion of an analog input from the Bridge Rectifier into a digital output representing the voltage of input power, by the Microcontroller; and sending the digital output from the Microcontroller to the Display Device for showing the value of the input power voltage to the user.

In accordance with yet another embodiment of the invention, is provided a method of detecting food spoilage, wherein a Control Switch is provided to allow the user to choose between displaying the concentration of gases or voltage of input power on the display device; the method comprising the steps of: sending a command from the Microcontroller to light up an LED indicator and display the concentration value of the gases on the display device when the user chooses to view the concentration of gases via the Control Switch; and, sending a command from the Microcontroller to light up an LED indicator and display the concentration value of the voltage of input power on the display device when the user chooses to view the voltage of input power via the Control Switch.

In accordance with yet another embodiment of the invention is provided a method of detecting food spoilage, optionally comprising the step of sending the output of the Bridge Rectifier as an input to the Microcontroller for starting the compressor of the refrigerator even when the Input Supply is of low voltage.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a schematic diagram of the linear power supply for the food spoilage detecting device.

Fig. 2 is a schematic diagram of the major components of a refrigerator having a food spoilage detecting device.

Fig. 3 is a schematic diagram showing in detail the major components of Fig. 2.

Fig. 4 is a flow diagram showing the steps involved in the detection and display of the level of food freshness using the food spoilage detecting device of the present invention.

It is to be noted that the above mentioned figures are with reference to a frost free or forced convection refrigerator. However, the teachings of the invention can be readily applied to other types of refrigerators and food storage devices like freezers, refrigerated shelves, hot cases, etc. also with or without minor modifications.

DESCRIPTION

Discussed below are some representative embodiments of the current invention.

The invention in its broader aspects is not limited to the specific details, representative devices and methods, and illustrative examples shown and described in this section in connection with the embodiments and methods. The invention according to its various aspects is particularly pointed out and distinctly claimed in the attached claims read in view of this specification, and appropriate equivalents.

It is to be noted that, as used in the specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise.

Fig. 1 is a schematic diagram of the linear power supply for the food spoilage detecting device. Power is required for the functioning of the components of the food spoilage detecting device, for Low Voltage Startability (LVS) of the refrigerator and for the functioning of the refrigeration cycle of the refrigerator. Linear power supply is needed in the first two since the electronic components used therein can get damaged if unregulated or high voltage power is supplied to them. Thus, the Input Supply (110) in the form of unregulated AC (Alternating Current) power is converted to regulated DC (Direct Current) power by the Linear Power Supply (200) before being supplied to a Microcontroller (100). The Input Supply (110) consists of the external AC supply rated at 220V/440V depending upon the grid power supply characteristics. However, there can be large fluctuations and in some situations very low voltage during peak hours. Thus, there is a need to stabilize the voltage and allow the compressor of the refrigerator to run in case of low voltage (using LVS feature).

The input supply enters a Step-down Transformer (120) to step down the input power. A Bridge Rectifier (130) is used to convert the stepped-down power into DC. The Voltage Regulator (140) comprises an IC (Integrated Circuit) which further converts it into 5V DC. The output of the Bridge Rectifier (130) is given as an input to the Microcontroller (100) for the LVS feature. The Microcontroller (100) can convert this into a digital output representing the voltage level of the compressor which may be displayed as High, Low, Normal, etc. on any display device. The output of the voltage regulator (140) is used as +VCc for different ICs that work on +5V. Two Electrolytic Capacitors (105, 115) and a Ceramic Capacitor (125) are also provided across GND/+VCc-

Fig. 2 is a schematic diagram of the major components of a refrigerator having a food spoilage detecting device. The refrigerator comprises a Sensor (300), a Display PCB (150) and a Main PCB (250). The Power Supply system, the Microcontroller (100) and other electrical and electronic components to run the refrigerator are mounted on the Main PCB (250). The Microcontroller (100) and Display PCB are explained in detail in Fig. 3.

In the present embodiment, the Sensor (300) is an air quality sensor. This sensor is located in the crisper tray which stores vegetables and/or fruits and is usually located at the bottom of the refrigerating compartment. The air quality sensor comprises:

- SnC>2 sensitive layer Micro Al203 ceramic tube Measuring Electrode Heater
- Crust

The sensitive Sn02 layer has low conductivity in clean air. When the target combustible gas comes in contact with this layer, the sensor's conductivity increases in accordance with the increasing gas concentration. Using an electro circuit, this change of conductivity is converted to corresponding output signal of gas concentration. The crust is made of plastic and stainless steel net. All the other components of the air quality sensor namely Sn02 sensitive layer, micro AI2O3 ceramic tube, measuring electrode and heater are fixed into the crust. The heater is provided to maintain the working temperature conditions for functioning of other sensitive components of the air quality sensor. The air quality sensor can detect concentrations from as low as a few ppm (parts per million) to as high as 10,000 ppm.

Fig. 3 is a schematic diagram showing in detail the major components of Fig. 2. The central component which controls the whole system is the Microcontroller (100). The microcontroller has three ports/pins, all of which can work as input as well as output ports. In the present embodiment, two of the ports work as an analog input port while the third is a digital input port. The output of the Bridge Rectifier (130) of the Linear Power Supply (200) is connected to one of the analog ports as an input. The Sensor (300) is connected to the Microcontroller (100) at another analog port. A Control Switch (170) of the Display PCB (150) is connected at the digital port.

The Microcontroller (100) converts the analog input from the Sensor (300) into corresponding concentration level of gases in ppm. Then it compares the measured concentration with some pre-defined ranges and determines the spoilage level accordingly. The spoilage level is indicated using an Indicator means comprising Light Emitting Diodes or LEDs (210, 220 or 230) on the Display PCB (150) and the measured concentration may also be displayed using a Display Device comprising Seven Segment Display (155,165,175 and 185) on the Display PCB.

In the present embodiment, the display PCB comprises LED Indicators (180,190 and 210, 220, 230), Seven Segment Display (155,165,175 and 185) and a Control Switch (170). The display means includes three different colored LEDs (green, yellow and red or any other color combination) to show the condition of the food products. Three different colored LEDs denote the shelf life of various food products. In a particular combination, green denotes that the food is fresh; yellow denotes that the food may get spoiled soon and should be consumed or removed soon; and red indicates that the stored food is unfit for consumption and should be immediately removed. The other two LED based indicators (180, 190) are provided to give an indication to the user whether the supply voltage (in Volts) is being displayed or the concentration of gases (in ppm) is being displayed.

The Seven Segment Display (155, 165, 175 and 185) is provided on the Display PCB (150) for showing the digits that represent the readings of the input voltage and/or the concentration of gases. It has 10 pins of which 7 pins are for 7 segments, one pin is for chip select (CS), one pin is for decimal point and one pin is for common GND/+Vcc. Common anode type four seven segment displays are mounted on display PCB and are connected to the common output port of the Microcontroller (100). These seven segment displays differ by chip select input (CS1, CS2, CS3 and CS4) pin. The microcontroller controls the display of all the seven segment displays individually using the CS input.

The Control Switch (170) is provided on the Display PCB (150) to control the display mode. The Control Switch (170) is connected to the third port of the Microcontroller (100) and provides a digital input. When this switch is pressed one time, the ppm level of gases is displayed in digital form (4 digits). When this switch is pressed again, the input supply voltage is displayed on same display board in digital form (3 or 4 digits). Accordingly, the Microcontroller causes the LED (180) to glow when the input supply voltage is being displayed and causes the LED (190) to glow when the ppm level of gases is being displayed.
As seen from Fig. 3, the output of the Microcontroller (100) contains seven Common Data Lines (160) for providing inputs to the segments of the seven segment displays. All five LEDs (180, 190, 210, 220 and 230) are also connected to the output of the Microcontroller (100) which gives them the command to light up/glow. In the present embodiment, only two LEDs will glow at any particular time. Either of (180) or (190) will glow depending upon the Control Switch (170) and only one of the LEDs (210, 220 or 230) will glow depending upon the freshness level in the crisper tray. Since the microcontroller also performs the function of comparing the ppm level of gases with pre-defined ranges, these pre-defined ranges are stored in microcontroller by programming. The process of comparing is also programmed in the microcontroller. After comparing, according to stored ranges microcontroller will light up the relative LED, i.e. (210) for Green or (220) for Yellow or (230) for Red.

The voltage can be displayed to inform the user about the voltage at which the refrigerator is working.

There can be large fluctuations in voltage, which would lead to improper functioning of the refrigerator.

Thus, the user can check the voltage to determine whether the refrigerator is functioning properly or not and whether the correct temperature is being maintained inside the food storage compartments. This is a secondary indicator of the freshness of the food because the rate of decomposition of the food depends largely on the temperature at which it is stored. The LVS or Low Voltage Startability is an additional feature which allows the compressor to run up to certain low voltages, thereby ensuring that the desired temperature is maintained inside the refrigerator even in case of low voltage.

Fig. 4 is a flow diagram showing the steps involved in the detection and display of the level of food freshness using the food spoilage detecting device of the present invention. In step SI the Sensor (300) is mounted preferably inside the vegetable box on the crisper tray. The vegetables and/or fruits to be stored are placed inside the crisper tray. In step S2 the conductivity of the Sensor (300) changes with changes in concentration of the gases which are emitted during decomposition of the organic compounds present in the vegetables and/or fruits. As the concentration of these gases increases, the conductivity of the sensor also increases. Accordingly the sensor will give an analog output indicative of the ppm level of the gases.

This serves as an input to the microcontroller in step S3 and the microcontroller converts the analog input from the sensor into a digital output, i.e. the ppm value of concentration. Similarly another analog input coming from the Bridge Rectifier (130) output also gets converted into a digital output. In step S4 the Microcontroller (100) compares the gas level with pre-defined ranges that have been pre-programmed in the microcontroller. The microcontroller checks that the ppm level lies in which predefined range. In step S5, the microcontroller will light up the corresponding LED based on the range determined in step S4.
In the present embodiment, when the food is fresh the ppm level of gases will be low and the Microcontroller (100) will give output at the pin connected to the green LED (210). Thus, the green LED will glow indicating to the user that the food is fresh. When the food starts decomposing, the sensor's conductivity will start increasing. When it crosses a pre-defined level, the microcontroller will give output at the pin connected to the yellow LED (220) instead of the green LED (210). Thus, the yellow LED will glow indicating to the user that the food should be consumed or removed soon to avoid further spoilage.

Similarly when the food gets decomposed further, the microcontroller will give output at the pin connected to the red LED (230). Thus, the red color LED will glow indicating to the user that the food is unfit for consumption and should be disposed off immediately.

It is well known that various types of gases are released upon decomposition of different types of food products. Several different types of air quality sensors are available which are sensitive to the various gases. Refrigerators usually have locations demarcated for different types of food products. For instance, milk products may be stored together in a particular location in the refrigerator and give off similar type of gases upon decomposition. Thus, the location and type of air quality sensor can be changed depending on the food whose spoilage has to be detected and its placement inside the refrigerator.

Several other variations are possible within the scope of the invention. There can be a provision to modify the predefined ranges by the user depending upon their preferences. The number of spoilage levels can also be changed along with the number and color of the LEDs. Further, instead of providing indication to the user using different colored LEDs, bulbs, semi-conductor lighting sources, speakers, alarms, electronic voice output devices, etc. could be used.

In case of refrigerators having means to connect to the internet and/or a telecommunications network, the food spoilage level may also be sent to the user via SMS (Short Message Service), MMS (Multimedia Messaging Service), etc. In another alternative, the spoilage/freshness level of the stored food and/or value displayed on the display device could be sent to an online database, website, Smartphone application (Android, iOS, etc.) and the like. The number of Seven Segment displays used can be varied based on the range and/or precision of the value to be displayed The display device may also be changed from Seven Segment Display to Liquid Crystal Display, Light Emitting Diode display, Plasma display, etc. Different systems for supplying power may be provided and other types of microcontrollers may also be used.

The invention is not limited to the embodiments which have been described and illustrated by way of example and numerous modifications and variations can be proposed without departing from the scope of the appended claims.

We Claim:

1. A refrigerator comprising a freezing compartment and a refrigerating compartment; characterized in that, a food spoilage detecting device is provided for at least one location inside the refrigerator.

2. The refrigerator as claimed in claim 1, wherein the food spoilage detecting device comprises:

- a Sensor (300) mounted inside the refrigerator for detecting the concentration of at least one of the gases released upon decomposition of the food;

- a plurality of Indicator means, each representing a spoilage level for the food items based on the concentration of the gases detected by the Sensor (300);

- a Microcontroller (100) for controlling the other components of the food spoilage detecting device;

- a Linear Power Supply (200) for supplying power to the components of the food spoilage detecting device.

3. The refrigerator as claimed in claim 2, further comprising:

- a Display Device connected to the output of the Microcontroller (100) for displaying the value of the concentration of gases and/or input power being supplied to the refrigerator;

- a Control Switch (170) for allowing the user to choose between displaying the concentration of gases or voltage of input power on the Display Device; and,

- a plurality of LED indicators (180, 190) for indicating whether the concentration of gases is being displayed or voltage of input power is being displayed on the Display Device.

4. The refrigerator as claimed in any of the claims 2 or 3, wherein the Sensor (300) is an air quality sensor.

5. The refrigerator as claimed in claim 4, wherein the air quality sensor comprises an Sn02 sensitive layer, a micro Al203 ceramic tube, a measuring electrode and a heater.

6. The refrigerator as claimed in any of the claims 2 to 5, wherein the Indicator means are in the form of light and/or sound output devices like LEDs, bulbs, semi-conductor lighting sources, speakers, alarms, electronic voice output devices, etc.

7. The refrigerator as claimed in any of the claims 2 to 6, wherein the Indicator means are in the form of a plurality of dissimilarly colored Light Emitting Diodes (LEDs).

8. The refrigerator as claimed in claim 7, wherein the Indicator means comprises three LED indicators (210, 220, 230) to indicate three levels of freshness of the food items stored in the compartment(s) where the Sensor/s (300) is/are provided; said LED indicators comprising:

a. a green colored LED (210) to indicate that the food is fresh;

b. a yellow colored LED (220) to indicate that the food should be consumed soon or removed from the refrigerator; and,

c. a red colored LED (230) to indicate that the food is unfit for consumption.

9. The refrigerator as claimed in any of the claims 3 to 8, wherein the display device comprises a plurality of Seven Segment Displays (155,165,175 and/or 185).

10. The refrigerator as claimed in any of the claims 3 to 8, wherein the display device optionally comprises a liquid crystal display, LED display, plasma display, etc.

11. The refrigerator as claimed in any of the claims 2 to 10, wherein the Linear Power Supply (200) comprises:

a. a Step-down Transformer (120) for stepping down an input supply (110);

b. a Bridge Rectifier (130) for converting the stepped down power into DC (Direct Current);

c. a Voltage Regulator (140) for converting the power from Bridge Rectifier (130) into DC power of a particular voltage (say 5V); said particular voltage depending upon the operating voltage of the other
components of the food spoilage detecting device; and,

d. a plurality of electrolytic and/or ceramic capacitors (105, 115 and/or 125).

12. The refrigerator as claimed in any of the claims 1 to 11, wherein the refrigerating compartment comprises at least one crisper tray and at least one food spoilage detecting device for detecting food spoilage in the crisper tray.

13. The refrigerator as claimed in any of the claims 1 to 12, wherein the refrigerator optionally comprises means to access the internet and/or a telecommunications network.

14. A method of detecting food spoilage in a refrigerator having a food spoilage detecting device as claimed in any of the preceding claims, comprising the steps of:

a. mounting the Sensor (300) in at least one location inside the refrigerator;

b. detection of the concentration of the gases in the proximity of the Sensor (300) using the change in the conductivity of a semiconductor layer (like Sn02), and giving an analog input to the Microcontroller
(100) from the same;

c. conversion of this analog input from the Sensor (300) into a digital output by the Microcontroller (100); the digital output representing the value of concentration of the gases;

d. comparing the gas concentration with pre-defined ranges that have been pre-programmed in the Microcontroller (100) to determine the freshness level of the food; and,

e. sending output from the Microcontroller (100) to the Indicator means for providing an indication of the freshness level to the user.

15. The method of detecting food spoilage as claimed in claim 14, further comprising the steps of displaying the concentration value of the gases to the user by sending the digital output obtained in step (c) to the Display Device.

16. The method of detecting food spoilage as claimed in any of the claims 14 or 15, further comprising the steps of: conversion of an analog input from the Bridge Rectifier (130) into a digital output representing the voltage of input power, by the Microcontroller (100); and sending the digital output from the Microcontroller (100) to the Display Device for showing the value of the input power voltage to the user.

17. The method of detecting food spoilage as claimed in any of the claims 14 to 16, wherein a Control Switch (170) is provided to allow the user to choose between displaying the concentration of gases or voltage of input power on the display device; the method comprising the steps of: sending a command from the Microcontroller (100) to light up an LED indicator (180) and display the concentration value of the gases on the Display Device when the user chooses to view the concentration of gases via the Control Switch (170); and, sending a command from the Microcontroller (100) to light up an LED indicator (190) and display the concentration value of the voltage of input power on the Display Device when the user chooses to view the voltage of input power via the Control Switch (170).

18. The method of detecting food spoilage as claimed in any of the claims 14 to 17, optionally comprising the step of sending the output of the Bridge Rectifier (130) as an input to the Microcontroller (100) for displaying the voltage level of the compressor on the Display Device.

19. The method of detecting food spoilage as claimed in any of the claims 14 to 18, optionally comprising the step of sending the spoilage/freshness level of the stored food and/or value displayed on the display device to the user by a messaging service like SMS (Short Message Service), MMS (Multimedia Messaging Service), etc.

20. The method of detecting food spoilage as claimed in any of the claims 14 to 19, optionally comprising the step of sending the spoilage/freshness level of the stored food and/or value displayed on the display device to an online database, website, Smartphone application and the like.