THE INCREASING CONSUMPTION OF JUICES WORLDWIDE AND THE ROLE OF TECHNOLOGIES Fruit juices and puree technology: examples of applied research. Roberto Massini | Italiafoodtec.com

1. Fruit juices and puree technology:
examples of applied research
Roberto Massini
formerly professor of Food Science & Technology
at the University of Parma, Italy
Africa's Big Seven: 21-23 June 2015, Johannesburg, South Africa
21 June 2015
THE INCREASING CONSUMPTION OF JUICES WORLDWIDE AND THE ROLE OF TECHNOLOGIES
New developments and techniques for juices and puree processing and packaging
and new products creating opportunities for growth

2. Pomegranate (Punica granatum) juice
Increasing request of pomegranate juice as a healthy food on the northern
hemisphere market.
Increasing production of pomegranate in southern hemisphere and,
especially, in South Africa.

3. Health benefits of pomegranate are due to high polyphenols content
(principally anthocyanins and phenolic acids).
Anthocyanins from pomegranate fruit possess higher antioxidant activity
than vitamin-E ( -tocopherol), -carotene, and ascorbic acid.
Compared to the pulp, peels contain more and different bioactive
compounds (principally hydrolyzable tannins), which can increase the
functional properties of the juice.
Husk
Peels
Arils (seeds surrounded by juicy aril)
highest phenol content, but
bitter and astringent taste

4. Maximizing functional properties while preserving sensory acceptability.
Arils separation: by a conventional grape destemmer.
Changing parameters as shaft velocity, drum velocity and blades position it
is possible to optimize the skin and connectival tissue separation.
Juice cold extraction: by a screw press.
The presence of a suitable amount of peels allows obtaining juice with
high antioxidant activity, but keeping the bitterness under the threshold
perceived as negative by the consumers.
Juice enzymation: by pectolytic enzymes.
By adopting appropriate operating conditions, the turbidity of the juice is
reduced without reducing, but increasing, the total polyphenols content.
A slight turbidity of the juice must be accepted, because a further stage of
flocculation or microfiltration would severely reduce antioxidant capacity.
Thermal treatment: by aseptic processing and packaging.
Full deaeration and HTST conditions allow limiting thermal damage.

5. Passive heat transfer enhancement for HTST
For three fruit products: cloudy orange juice, apricot and apple puree, the
heat transfer enhancement by helically corrugated shell and tube was
evaluated with respect to smooth wall tube.
Pilot plant layout
Corrugated tube
OVERHEATED
WATER PUMP
HEATER
WATER/STEAM
EXSPANSION
VESSEL
STEAM
WATER
BACKPRESSURE VALVE
COOLING SECTION
HEATING SECTION
WATER
PRODUCT
FEEDING TANK
PUMP
OVERHEATED
WATER PUMP
HEATER
WATER/STEAM
EXSPANSION
VESSEL
STEAM
WATER
BACKPRESSURE VALVE
COOLING SECTION
HEATING SECTION
WATER
PRODUCT
FEEDING TANK
PUMP

6. 0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
0 5000 10000 15000 20000
Average Reynolds number
Pressurelosses(bar)
Not corrugated wall heating Corrugated wall heating
Not corrugated wall cooling Corrugated wall cooling
0
500
1000
1500
2000
2500
3000
3500
0 5000 10000 15000 20000
Average Reynolds number
Overallheattransfer
coefficient(W/m2
·K)
Not corrugated wall pipes Corrugated wall pipes
Not corrugated wall pipes Corrugated wall pipes
Cloudy Orange juice (11.2 °Bx):
Flow index n = 1.0 (25-65°C) Newtonian flow behaviour
Consistency coefficient K = 0.0019 (25°C) 0.0008 (65°C) LOW
Variations of the overall heat transfer (a) and pressure drop (b)
as a function of the generalized Reynolds number
The increase of the overall heat transfer coefficient obtained with corrugation
is modest, because Newtonian fluids at low viscosity have turbulent flow even
with lower flow rates. However, it is relevant the increase of pressure drops.
a b

7. Apple puree (11.8°Bx):
Flow index n = 0.322 (25°C) 0.341 (65°C) Pseudoplastic flow behaviour
Consistency coefficient K = 9.9957 (25°C) 7.1437 (65°C) HIGH
Variations of the overall heat transfer (a) and pressure drop (b)
as a function of the generalized Reynolds number
The corrugation effect for heat transfer resulted almost of no value, because
for high consistency fluid the flow can be considered always laminar.
The increase in pressure drops is not considerable.
0
500
1000
1500
2000
0 20 40 60 80 100
Average Reynolds number
Overallheattransfer
coefficient(W/m
2
·K)
Not corrugated wall pipes Corrugated wall pipes
Not corrugated wall pipes Corrugated wall pipes
0.0
1.0
2.0
3.0
4.0
5.0
0 20 40 60 80 100
Average Reynolds number
Pressurelosses(bar)
Not corrugated wall heating Corrugated wall heating
Not corrugated wall cooling Corrugated wall cooling
a b

8. Apricot puree (10.8°Bx) :
Flow index n = 0.273 (25°C) 0.347 (65°C) Pseudoplastic flow behaviour
Consistency coefficient K = 1.7641 (25°C) 0.8090 (65°C) MEDIUM
Variations of the overall heat transfer (a) and pressure drop (b)
as a function of the generalized Reynolds number
For this intermediate consistency fluid the increase in performance of the
corrugated wall pipe is noticeable, because the transition from laminar to
turbulent flow. Even more remarkable is the effect for the pressure drops.
0
500
1000
1500
2000
2500
3000
3500
4000
0 500 1000 1500 2000 2500 3000
Average Reynolds number
Overallheattransfer
coefficient(W/m
2
·K)
Not corrugated wall pipes Corrugated wall pipes
Not corrugated wall pipes Corrugated wall pipes
0.0
1.0
2.0
3.0
4.0
5.0
0 500 1000 1500 2000 2500 3000
Average Reynolds number
Pressurelosses(bar)
Not corrugated wall heating Corrugated wall heating
Not corrugated wall cooling Corrugated wall cooling
a b

9. The corrugated tubes may or may not increase the heat transfer according to
the rheology of the treated product.
More precisely, there is a real advantage only if, other conditions being equal,
the corrugation induces the transition from laminar to turbulent flow.
On the other hand the corrugated tubes cause an unfavorable, more or less
pronounced, increase in pressure drop.
Product s rheological behavior More suitable heat exchanger
Newtonian, low viscosity Smooth wall tube
Pseudoplastic, high consistency Scraped surface
Pseudoplastic, medium consistency Corrugated wall tube

10. Foreward control to reduce thermal damage
Simplified diagram of a process system commonly used for fruit juice

11. HEAT EXCHANGER+ -
Tsp
Tout
product
changes:
DTin , DMp , Dcp
heating fluid
changes:
DThf / DMhf
e m
PID VALVE
change: DOHTC
PLC
RTD
Current control of the heating unit: reactive "feedback"
Undershoot
Range of normal variability
When incoming variables
undergo rapid transients,
feedback control is not able to
maintain outlet temperature
within a narrow band.
To avoid frequent recycle of
the product, the temperature
set point must be very
oversized, with a systematic
large overprocessing.

12. HEAT EXCHANGERVALVE+ -
Tsp
Tout
+
+
FEEDFORWARD
in PC/PLC
PID in PLC RTD
DThf/DMhf
RTD
T / M
meter
Flow-meter
DMp
DTin
change: DOHTC
change: Dcp
Integration with predictive control to manage properly the fast transients
10
Feedback
Control
Feedback +
Feedforward
Control

13. The predictive control allows to remarkably reduce the average heating
temperature of the product and this, in addition to reducing the thermal
damage to the nutritional and sensory properties, reduces the frequency of
stop of production necessary to clean the plant.
However, despite the low cost of the processing system adaptation, the
feedforward control is not used.
Often, on the other hand, in the PID feedback control the derivative
function is disabled.
This can only be justified by knowledge reasons:
- While it is only requested a generic technical expertise to set up and
tune the feedback control system, the feedforward operation algorithms
are based on the physical laws of heat exchange.
- The application of a heat treatment largely oversized creates a strong but
false security, because it diverts attention from the overall needs of
process control.

14. All cold to preserve the natural properties
The inactivation of microorganisms in juices by Supercritical carbon dioxide
(ScCO2) nonthermal processing was developed to combine it with the cold
extraction of the fruit and the refrigerated storage of final product.
Pilot plant for ScCO2 processing and aseptic packaging

15. 31.1°C
73.8bar
Phase diagram for carbon dioxide
The cold pasteurization with ScCO2 has been studied by many authors, but
with discordant results and, however, by using small laboratory apparatus.
Our continuous flow pilot plant has capacity up to 40 l/h and has been
designed to make it scalable up to productive sizes.
A supercritical fluid has high
diffusivity such as a gas, but is
a solvent such as a liquid.
Theoretically ScCO2 can
destroy microbial cells with
the following effects:
- Solubilization of cell wall
components;
- Acid denaturation of
cytoplasm components;
- Laceration of the cell in the
decompression phase.

16. After many experiments were identified plant and operating conditions
adequately effective.
In both clear and turbid apple juice (pH = 3,25 - 9,8 °Bx), the ScCO2
treatment for 90 seconds at 40°C and 100 bar reduced by at least
99.999% or 5 logs the inoculum of three standard micro-organisms:
- Listeria innocua,
- Lactobacillus plantarum, and
- Saccharomices cerevisiae.
Treatment with ScCO2 has a positive effect on the texture of apple juice,
by increasing the consistency and the degree of pseudoplasticity.
Because pectolytic and oxidative enzymes are not inactivated, it is
necessary to remove air from the headspace of package and store the
product at refrigeration temperatures.
These conditions, however, are necessary to ensure the retention of
excellent quality properties.

17. Thank you for your attention
roberto.massini@gmail.com

18. www.italiafoodtec.com