Non-invasive technique for determining the quality and
ripeness of fruit using UV-visible spectroscopy

 

OBJECTIVES

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·        
To determine the quality of
fruits like grapes, apples and oranges based on composition of nutrients using
UV –visible spectroscopy.

·        
To determine the ripeness of
fruit based on the chlorophyll   content in the fruits using UV-visible
spectroscopy.

·        
To design a hand held hardware
setup to display the gradation (A,B,C.etc) of the fruit and its ripeness in
percentage.

 

INTRODUCTION

 

In
a study from 52 low and middle income countries it was found that 77.6% of men
and 78.4% of women consume less than the minimum recommended servings of
fruits. Also about 5.2 million deaths has been recorded worldwide due to
inadequate fruit and vegetable consumption in 2013.Hence The
World Health Organization (WHO) has been accentuating the need to include
sufficient amount of fruits and
vegetables as a prominent part of the daily diet.

 

Its benefits include cutting down the risk of cardiovascular
diseases and certain types of cancer and strengthening the immune system. Fruits
are rich in vitamins minerals and antioxidants, high on carbohydrates, and low
on fats hence making them a driving force for a healthier way of living.

 

The
modern lifestyle has demanded fruits to take different forms (packed, canned,
frozen) which requires suitable techniques of manufacturing and processing. Thus
modern food processing and food preservation techniques have become a growing
concern and a subject of interest. Food preservation techniques employ food
additives that prevent food degradation by slowing down the microbial growth.
They are also used in the acceleration of ripening of fruits which is a
chemical process.

 

Hence
close monitoring of this process is necessary to observe the changes in various
stages of the process and to assess the effects of additives. Despite,
contributing to longevity of food products and retainment of nutrients,
degradation of quality becomes inevitable with time under various conditions.

 

Non
destructive methods of testing food samples like spectroscopic analysis have
found applications in the determination of quality attributes and
authentication of food quality. Since most fruits fall under the UV-Vis region
in the electromagnetic spectrum, UV spectroscopy is the most sought after
method in food quality detection.

 

LITERATURE SURVEY

Senyurt, A. F.; Warner, D.; Narayan, V.S. of DePuy
Orthopaedics Inc., Warsaw, IN has estimated the
antioxidant content in stabilized UHMWPE materials 1. The typical UV absorption spectrums of the film samples
measured at different thickness was obtained and the correlation between the
film thickness and UV- absorption of HPAO-containing films was established.

Hong-Wen Gao has
determined the trace amounts of Calcium using spectrophotometric methods 2. The chromogenic reagents, 3- (2-chlorophenylazo)-6-(2-
bromophenylazo)-4, 5-di- hydroxynaphthalene-2, 7-disulfonic acid, 1 ethanedial-bis
(4-hydrobenzoylhydrazone), 2 chloridazon C, 3 rhodamine B4 and others have been
used for the determination of calcium by spectrophotometry. Alizarin (ALZ) has
been found to sensitively complex calcium at pH 5.2;

Péter Szuvandzsiev, Lajos Helyes, Andrea Lugasi, Csongor
Szántó, Piotr Baranowski*, and Zoltán Pék
have addressed the issue of analytical quantification of components which
involves destructive, time and labor consuming methods of assessment3. The antioxidant components of
tomato have been estimated by using VIS-NIR reflectance data by handheld
portable spectrometer.’

María J. MARTELO-VIDAL and Manuel VÁZQUEZ have
evaluated Ultraviolet, Visible, and Near Infrared Spectroscopy techniques for
the analysis of Wine Compounds4.Spectroscopy
of UV-VIS-NIR combined with chemometric analyses was used as a non-destructive
technique to build models for the quantitative characterization of the main
compounds of wine. The work in mixtures can give insight into how interferences
affect the performance of calibrations in wines.

Manuela Zude* has
proposed a study aimed at investigating
a non-destructive, rapid instrumental method to measure fruit maturity and
quality more precisely 5

A.KRÜSS Optronic GmbH has
developed a technique to measure ripeness of fruits and vegetables using refractometry
6. It is possible to accurately measure
the sugar concentration in degrees Brix (also known as °Brix, Brix, %Brix), which
It can be measured by both the density and the refractive index (nD).

Hailong Wang, Jiyu Peng, Chuanqi Xie, Yidan Bao and Yong
He have proposed a review on fruit quality
evaluation using spectroscopy technology7.Researchers
all over the world have investigated the potential of various technologies, including
acoustic techniques, spectroscopic techniques, machine vision and electronic
noses, for the assessment of fruit qualities. Among all these technologies,
spectroscopic techniques have drawn great attention for their prominent
advantages: (1) they are nondestructive methods which enable the acquisition of
fruits’ internal quality parameters without damaging their surfaces; (2) the measurement
processes are simple and rapid, as no complex pretreatments or chemical
reactions on fruit samples are needed; (3) they enable the detection of several
fruit internal attributes simultaneously. As a disadvantage, however, the small
point-source measurements which are commonly used in spectral assessment cannot
provide spatial information, which is important in many fruit quality
evaluation instances.

Vandana Patil, Sachidanand Angadi and Subash Devdhe
has developed a simple, accurate, precise and economic UV spectroscopic method
for the determination of quercetin. 8

METHODOLOGY

UV
VISIBLE SPECTROSCOPY

UV spectroscopy is an absorption spectroscopy
in the UV region of the electromagnetic spectrum. It covers a range of
wavelength between 190 and 380 nm. Molecules containing pi electrons or non
bonding electrons absorb energy in the form of ultraviolet or visible light. A
UV spectrophotometer is widely used in the detection, qualitative and
quantitative analysis of such components.

BEER-LAMBERTS
LAW

UV spectroscopy works by the principle of
Beer lamberts law which states the linear relationship between absorbance and
concentration of an absorbing species.   

                                           A = a () * b * c

Where A is the
absorbance measured, a () is the absorptive coefficient, b
is the path length and c is the concentration of the analyte.

BLOCK DIAGRAM AND WORKING

When a beam of
light from a radiant source is passed through the sample, it absorbs the
incident light on a particular wavelength and transmits the rest of the light.
The absorbance measured from the spectrophotometer corresponds to the
concentration of the sample under test. The obtained absorption spectrum is
sent as an input to a microcontroller. Depending on the programmed standard
value, the gradation will be displayed on the readout device. Depending on the
chlorophyll content measured from the spectrum, the stage of ripening will be
monitored to indicate the maturity of fruits.

 

 

 

 

 

 

DETERMINATION
OF WAVELENGTH

 

 

 

 

 

 

 

 

The samples are prepared. The wavelengths of
tartaric acid, malic acid, oxalic acid present in the fruits are determined by
placing the samples in the UV spectroscopy. The process is repeated for
different intervals of time and the change in wavelengths due to the chemical
reactions are determines. The lookup table is prepared with these data and the
data is fed to the controller.

HARDWARE
DESIGN:

The hardware includes UV transmitter and
detector for the wavelength determined using spectrophotometer. The output
voltage from the detector is given to the microcontroller PIC16f887 in which
the appropriate code is embedded by referring the lookup table obtained by
analysis various samples at various time instants such that the corresponding
amount of impurity present in the sample is displayed in LCD with grades.

 

UV
RECEIVER

 

SAMPLE

 

         UV
TRANSMITTER

 

 

 

 

MICROCONTROLLER    (ARDUINO)
 

 

 

 

 

 

             BLOCK DIAGRAM FOR HARDWARE DESIGN

In the above block diagram the sample is
placed between the UV transmitter and receiver. The output of the receiver is
in the form of voltage which is given to LCD for display.

UV
LIGHT EMITTING DIOIDE

Light emitting diodes (LEDs) are used as
source to emit light in the ultraviolet range, although practical LED arrays
are very limited below 365nm. LED efficiency at 365 nm is about 5 to 8 %,
whereas efficiency at 395 nm is closer to 20%, and power outputs at these
longer UV wavelengths are also better. The LEDs with centre wavelength from
300nm to 400nm are ideal for industrial applications. These LEDs feature high
reliability and high output power. In this project, UV LED is connected in
series with a resistor of 220 ohm and a supply of 5V DC is given. The light
emitted is passed through the sample.

UV
DETECTOR

UV detector sensor used is ML8511 UVB ray
sensor. This sensor detects 280 to 390 nm light most effectively. This is
categorized as a part of the UVB (burning rays) spectrum and most of the UVA
(tanning rays) spectrum. It outputs an analog voltage that is linearly related
to the measured UV intensity (mW/cm^2). In this sensor there are 5 pins .The
required supply voltage is 3.3V or 5V. The VCC pin is connected to 5v. The
ground pin is grounded and the out pin is given to the ADC pin of the
microcontroller. The pin diagram of ML8511 is shown below,

 

The
sample absorbs the light and transmits the part which is detected by detector
sensor. The output voltage is based on the transmitted light. This sensor has
inbuilt amplifier which converts the photocurrent to voltage depending on the
UV intensity .This offers an easy interface with external circuits such as ADC.

ARDUINO

The Arduino Uno is a
microcontroller board based on the ATmega328 with 14 digital
input/output pins (6 can be used as PWM outputs), 6 analog inputs, a
16 MHz crystal oscillator, a USB connection, a power jack, an ICSP
header, and a reset button. It contains everything needed to support the
microcontroller; simply connect it to a computer with a USB cable or power it
with an AC-to-DC adapter or battery to get started.

 

Microcontroller

ATmega328

Operating Voltage

5V

Input Voltage (recommended)

7-12V

Input Voltage (limits)

6-20V

Digital I/O Pins

14 (of which 6 provide PWM output)

Analog Input Pins

6

DC Current per I/O Pin

40 mA

DC Current for 3.3V Pin

50 mA

Flash Memory

32 KB (ATmega328) of which 0.5 KB
used by boot loader

SRAM

2 KB (ATmega328)

EEPROM

1 KB (ATmega328)

Clock Speed

16 MHz

 

The ATmega328 provides
UART TTL (5V) serial communication, which is available on digital pins 0 (RX)
and 1 (TX). Serial communication is facilitated by Software serial library.

Arduino nano is a
compact board similar to Arduino uno shown in figure below.

 

 

16X2
LIQUID CRYSTAL DISPLAY:

LCD screen is an electronic display module
and find a wide range of applications. A 16×2 LCD display is very basic module,
economical, easily programmable, have no limitations of displaying even custom
characters. The supply voltage given to pin 2 of LCD is 5V. The contrast
adjustment is done by connecting   a
variable resistor to pin 3. The four low order bi-directional data bus lines
are not used for 4 bit operation.

The UV LED, UV detector and PIC
microcontroller are given power supply of 5V DC.  The light from UV LED passes through the
sample. The transmitted light is received by the detector. The output of the
detector is in the form of analog voltage which is given to pin 2 of the
microcontroller to convert the analog signal to digital signal. The crystal
oscillator is connected to pin 13 and 14 of microcontroller. The frequency of
the crystal oscillator is 16MHz. the data bus of LCD is connected to PORT B of
microcontroller.  Based on the adulterant
in the sample placed between the UV LED and detector, the detector output
voltage varies correspondingly which is displayed as grade in LCD.

 

 

IMPLEMENTATION

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

WORKPLAN

 

Review 1: Preparation
of samples for various fruits and determination of nutrient contents using
UV-1800(Available in our department laboratory). Based on the output, UV-LED
source and UV detectors will be selected

 

Review 2: Design and
Implementation of necessary signal conditioning circuits for the hand-held
device

 

Review 3: Completion
and testing of Final Hand-held device for various fruits and vegetables

 

EXPECTED
OUTCOME/RESULTS

 

·        
We should be able to grade the quality of the
fruits based on the nutrient contents.

·        
We should be able to determine the ripeness
of fruits based on the chlorophyll content

·        
The degradation of quality with time will be
determined by using this method.

 

 

 

 

APPLICATIONS:

·        
Presence of adulterants
above the prescribed rate and detection of forbidden additives can be
determined

·        
Self detection of
nutritional content in the diets of patients who require close monitoring

·        
Quality analysis of fruits
during imports and exports

·        
Easy discrimination between
organic and inorganic products

·        
Facilitation of food quality
department’s work by quick identification of low grade products during
inspections. This helps in reducing the harmful and inorganic fruits and
vegetables into the market.

·        
This easy-to-use and
portable device enables commoners to check the quality of the purchased fruits
by themselves

 

CONCLUSION

 

Quality of fruits and
vegetables is one of the primary needs as food consumers are susceptible to any
form of contamination that may occur during the production process. Consuming
similar additives more than the prescribed rate increases the risk of food
borne diseases. Hence continuous monitoring and regulation of food products especially
fruits are essential periodically. Our device ensures quality measurement at
fingertips. The simplicity of our innovation makes it accessible to both
consumers and quality regulation bodies.

 

REFERENCES

1
Senyurt, A. F.; Warner, D.; Narayan, V.S. DePuy Orthopaedics Inc., Warsaw, IN. “Quantitative
Estimation of Antioxidant content in Stabilized UHMWPE Materials.”Poster No.
60- 55th Annual Meeting of the Orthopaedic Research society

2 Hong-Wen Gao “Spectrophotometric
Determination of Trace Amounts of Calcium Using the Calcium Complex with
Alizarin.”J.Braz Chem. Soc., Vol.13, No.1, 78-81, 2002.

3 Péter
Szuvandzsiev, Lajos Helyes, Andrea Lugasi, Csongor Szántó, Piotr Baranowski*,
and Zoltán Pék. “Estimation of antioxidant components of tomato using VIS-NIR
reflectance data by handheld portable spectrometer” Int. Agrophys., 28, 521-527
doi: 10.2478/intag-2014-0042, 2014

4 María J.
MARTELO-VIDAL and Manuel VÁZQUEZ. “Evaluation of Ultraviolet, Visible, and Near
Infrared Spectroscopy for the Analysis of Wine Compounds.” Czech J. Food Sci.
Vol. 32, No. 1: 37–47, 2014

5 Manuela Zude* “Non-destructive
prediction of banana fruit quality using VIS/NIR spectroscopy” Fruits, vol. 58,
p. 135–142, 2003

6 A.KRÜSS Optronic
GmbH.”Measuring ripeness in the fruit and vegetable industry- Measuring Brix
using refractometry” AP130422.001 Alsterdorfer
Strasse 276-278 • 22297 Hamburg | Germany

7Hailong Wang, Jiyu
Peng, Chuanqi Xie, Yidan Bao and Yong He. “Fruit Quality Evaluation Using
Spectroscopy Technology: A Review” Sensors, 15, 11889-11927; doi: 10.3390/s150511889,
2015

8 Vandana Patil,
Sachidanand Angadi and Subash Devdhe “Determination of quercetin by UV
spectroscopy as quality control parameter in herbal plant: Cocculus hirsutus”
Journal of Chemical and Pharmaceutical Research, 7(1):99-104. ISSN: 0975-7384. CODEN
(USA):JCPRC5, 2015