Its about use of UV radiation in fruit juice processing.

1. Presented by
BISWAJIT SINGH DEB
M. Tech in Food process Engineering
Agricultural and Food Engineering Department
IIT Kharagpur
Ultraviolet radiation as a non-thermal
treatment for the inactivation of
microorganisms in fruit juice

2. CONTENTS
1. Introduction
2. UV as a Non-thermal treatment
3. Types of UV radiation
4. UV-C
5. Types of method
6. Materials and Method
6. Result and Discussion
8. Conclusion
9. References

3. Introduction
Fruit juice can be spoiled due to the growth of micro-
organisms.
Yeasts and moulds, Lactobacillus, Leuconostoc and
thermophilic Bacillus are common spoilage micro-
organisms of fruit juice .
Microorganisms suspended in air are more sensitive
to UV-C radiation than microorganisms suspended in
water, which are more sensitive to radiation than
microorganisms in juice.

4. The penetration effect of UV-C radiation depends on
- Type of liquid
- UV-C absorptivity
- Soluble solids and
- Suspended matter in the liquid.
The greater the amount of soluble solids, the lower
the intensity of penetration of the UV-C light in the
liquid.
Ultraviolet treatment of juices is difficult due to their
low UV transmittance through the juice because of
the high suspended and soluble solids.

5. why it is non-thermal treatment ?
Ultraviolet treatment is performed at low temperatures and
is considered as a non-thermal disinfection method .
During the treatment no significant nontoxic by-products are
formed and requires very little energy as compared to
thermal pasteurization processes.
Fruit juice that undergo thermal pasteurization or sterilization
tend to change colour and lose some of its aromas and
vitamins during the process of heating.
Unlike juices that are treated with UV radiation, which tend
to maintain their aroma and colour.

6. Ultraviolet radiation
UV-A
WAVE LENGTH(320-
400nm)
UV-C
WAVE
LENGTH(200-
280nm)
UV-B
WAVE
LENGTH(280-
320nm)
UV radiation covers a small
part of the electromagnetic
spectrum.
 It includes radio waves,
microwaves, infrared
radiation, visible light,
X- rays and γ- radiation.
UV radiation categorized as
1. UV-A (320–400 nm)
2. UV-B (280–320 nm)
3. UV-C (200–280 nm).

7. UV-C
UV-C is considered to be germicidal against micro-
organisms such as bacteria, viruses, protozoa, yeasts,
moulds and algae where the highest germicidal effect
is obtained between 250 and 270 nm.
Therefore, the wavelength of 254 nm is used for the
disinfection of surfaces, water and various liquid food
products such as fruit juice.
The penetration depth of UV-C radiation through the
surface of liquids is very short, with the exception of
clear water.

8. How does UV work?
In order to kill
microorganisms, the UV rays
must actually strike the cell. UV
energy penetrates the outer cell
membrane, passes through the
cell body and disrupts its DNA
preventing reproduction.
 The degree of inactivation by
ultraviolet radiation is directly
related to the UV dose applied to
the water.

9. Materials and methods

10. Novel pilot-scale UV
A reactor typically consists of a stainless steel inlet and outlet
chamber with a stainless steel corrugated spiral tube between
the chambers.
Inside the spiral tube is an UV germicidal lamp which is
protected by a quartz sleeve.
The liquid flows between the corrugated spiral tube and the
quartz sleeve.
The tangential inlet of the reactor creates a high velocity and
turbulence in the inlet chamber and brings the liquid
(product) into contact with the UV radiation.

11. The liquid is pumped from the inlet chamber into the actual
reactor.
 The gap between the quartz sleeve and the corrugated spiral
tubing at a minimum flow rate (Fr) of 3800 L/ hr with a
Reynolds value (Re) in excess of 7500, indicating turbulent
flow.
Fig. novel pilot-scale uv system

12. Commercial-scale UV systems
The commercial-scale unit consists of 10 UV lamps
(254 nm) in series, connected to water and product
feed lines, as well as outlet points.
For flow rates above 3800 L /h the Reynolds value is
calculated to be more than 7500 which indicates
turbulent flow patterns.
Because the high turbulent flow patterns help to
prevent clumping of microorganisms and assist in the
efficiency of UV radiation by increasing the exposure
of the liquid to UV radiation.

13. Fig. Commercial-scale UV systems
The UV-C light is absorbed by the DNA and causes a
cross linking between the neighbouring thymine and
cystine nucleoside bases, that will lead to cell death of the
various bacteria, viruses and moulds.

14. Cleaning of the units
The commercial and pilot-scale units were cleaned after
every juice treatment using standard ‘Cleaning In Place’
(CIP) processes.
-The equipment was rinsed with warm water
(50 °C) for 10 min.
-after a 1.0% alkaline solution was circulated
for 30 min at 75 °C, followed by a warm
water rinse at 50 °C for 5 min.
-Lastly, a 0.5% Perasan solution was
circulated for 10 min before a final rinse with
cold water.

15. Dosage measurement
The radiant exposure (dosage) is expressed as watts-
second per square centimetre (W s/ cm2) or joules per
square centimetre (J /cm2) and characterizes the energy
delivered per surface area of the treatment device.
Therefore, UV dosage (D) is determined as time (T )
multiplied by irradiance (I ).
For liquids, the UV dosage is expressed as J /L .

16. UV dosage per area
1.According to the manufacturers, The length of the quartz
sleeve used was 0.860 m, with an outer surface area (As) of
661.93 cm2.
2.The area between the quartz sleeve and corrugated spiral
tubing is termed the annulus and the volume there of was
determined as being 0.675 L or 0.00068 m3.
3. According to the manufacturers, the energy transmission
rate (total UV-C output) to the constant surface of the
quartz sleeve (As=661.93 cm2) from the UV lamp is 25.5W
(watts) UV-C.

17. The intensity (I ) per reactor can be calculated as follow:
Intensity (I)=Total UV -C output(W)/Area (cm2)
=25.5 W/661.93 cm2
=0.039 W/ cm2
=38.5 mW/ cm2
The retention time (T) of the product per reactor can be calculated
as follow:
Retention time (T)=Volume of the reactor (L)/Flow rate (L/ h)
=0.675 L/4 000 (L/ h)
= 0.675 L/1.111 (L/ s)
=0.608 s
Therefore the UV dosage (D) per surface area for one reactor with
continuous flow is calculated as follows:
Dosage =Intensity (I)*Time ( T)
= (38.50 mW/cm2) *0.608 s
= 23.408 mW.s/cm2
=23.408 mJ/cm2

18. UV dosage per volume
At a flow rate (Fr) of 4000 L/ h the product retention
time (T) is 0.608 s per reactor therefore the UV
dosage per litre of liquid treated for one reactor with
continuous flow is calculated as follows:
Dosage =Total UV -C output (W)/Flow rate(L /s)
= 25.50 W/1.11 (L /s)
= 22.95 W. s /L
= 22.95 J/ L

19. Ultraviolet Dosage Required For 99.9% Destruction of
Various Organisms (mW-s/cm2 at 254 nanometre)

20. UV-C processing of the fruit juices
A sample volume of either 20 L or 80 L was placed into the
holding tank (8–10 °C) of either the pilot or commercial UV
treatment unit.
A speed controlled sanitary centrifugal pump was used to
achieve a flow rate of 4000 L /h in both units.
The juice was processed at 8–10 °C, and due to the short
contact time, no heat transfer from the lamps to the juice was
recorded after processing.
An in-line sampler was used to extract the juice aseptically
from the flow stream without stopping the treatment process
to avoid excessive exposure of the juice in the UV reactor
during sampling.

21. Result and Discussion
The log10 reduction of Escherichia coli, aerobic
plate count (APC) bacteria (cfu/ ml) and yeasts
and moulds in apple juice after the exposure to
different UV dosages (J/ L ).
 3.5 log10 reduction for the
APC bacteria and 3.0 log10
reduction for the YM after a
UV dosage of only 230 J/L.
The UV dosage of 230 J/ L
was enough to eliminate the
APC bacteria as well as the
YM.
After the 1377 J /L UV-C
exposure 7.42 log10 reduction
of the E. coli was obtained.

22. Conclusion
UV radiation was successfully applied to reduce the
microbial load in different fruit juices.
The application of UV-C radiation is vast, and can be
successfully used to reduce the microbial load in
different single strength fruit juices and nectars.
Novel UV system has low running costs, use less energy
than thermal pasteurizers and require little maintenance.
All these factors contribute to lower capital and running
costs and a good quality and safe product for the
consumer.

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