1. University of Foggia - Italy
Department of the Science of Agriculture, Food and Environment
Physico-chemical evaluation of olive olive paste and olive oil obtained by a new partial destoner machine implemented in an industrial olive oil extraction plant
Prof. Alessandro LEONE

2. Olive oil extraction process
The olive oil extraction process is constituted by 5 differents steps: Olive cleaning; Olive crushing; Malazation; Solid-liquid separation; Liquid-liquid separation
The topic of this study is the crushing phase.
In the world about the 90% of the mill use for the milling phase, the mechanical crushers for example disk mill or hammer mil or knife mill
Olio

3. Olive milling by using the mechanical crushers
The aim of milling is to reduce the olives to a homogeneous paste by breaking the pits, skin and pulp cells until to produce an olive paste with pit fragments.
When the traditional mechanical crusher is used the olive oil is extracted from the olive pasts containing the pit fragments. + =
Olive paste with fragments of the stone
University of Foggia, Department of the Science of Agriculture, Food and Environment

4. Olive pitting by using the total destoner machine
Pitting consists in removing the olive pits (used as fuel purpose) and reducing the only pulp into a paste. Following, the olive oil is extract from the olive pastes without the pit fragments.
In the early 2000s thanks to the cooperation between universities and and plant construction companies has been designed a total destoner machine for the pitting operation instead the milling operation.
Pits recovered
Real photo of a total destoner machine
(Alfa Laval inc.)
University of Foggia, Department of the Science of Agriculture, Food and Environment

5. Total destoner machine
Real photo of the total destoner machine (Pieralisi inc.)
Positive aspects
More flavour of the oils
Recovering of all pits as fuel (about 25% of the olives)
Husk can be used for animal feeding
Negative aspects
Olive paste is not enough homogenous for an optimal malaxation
The absence of pit fragments in the olive paste leads to technological problems during the malaxation and centrifugal extraction
loss of oil’s extraction yield of about 15%
for these reasons the total destoner is no longer used

6. The goal of the research
To design and develop a new destoner machine model that allowed to recover part of pit fragments (about 50%) and to avoid losses in extraction yield.
This is the machine that we have disigned with a private company. After the machine has been patented.
The machine is constituted by three different section: crushing section to produce the olive paste; depitting section that allows the partial separation of about 50% of pit fragments and finally the malaxation section that collects the olive paste contain only half of the pit fragments.
University of Foggia, Department of the Science of Agriculture, Food and Environment

7. Partial destoner machine
Real photo of the partial destoner machine
Rotary drum
Reel pitting
University of Foggia, Department of the Science of Agriculture, Food and Environment

8. University of Foggia, SAFE Dept.
Comparative tests
Coratina variety
Malaxation t T: 40’; 27°C
Mass flow rate: 3000 kg/h
PDM HC
Viscosity of the olive pastes
Olive oil extraction yield
Olive oil quality
Folowing we have carried out the comparative tests in an industrial olive oil mill. During the tests has been compared the use of the Partial destoner machine and hammer crusher (control thesis).
The tests has been carried out with olives of Coratina variety, the malaxation has been carried out for 40 min at 27°C and the mass flow rate has been 3000 kg/h
During and after the tests we have valued the viscosity of the pastes, the olive oil extraction yield and the olive oil quality
University of Foggia, SAFE Dept.

9. Results: viscosity
In this slide you can see the shear rate vs apparent viscosity, the graphic shows that there is a significant differences between the olive paste of the HC and PDM.
This due to the absence of a part of the stone in the olive pastes obtained by using the partial destoner machine
University of Foggia, Department of the Science of Agriculture, Food and Environment

10. Results: quantitative parameters
Between the two thesis there is not significant differences about the yiele and EE.
this means that with the use of the PDM is possible avoid the losses of the yield
University of Foggia, Department of the Science of Agriculture, Food and Environment

11. Results: qualitative parameters
There is not significant difference about the free acidity, spectrophotometric indices and total phenolic compounds, but there is a decrese of the peroxide index.
University of Foggia, Department of the Science of Agriculture, Food and Environment

12. University of Foggia, SAFE Dept.
Volatiles compound
Sensory evaluation
About the volatiles the sum of the all compounds is increased when the PDM has been used.
In addition about the sensory elavuation, fruity and bitter has been more evident in the oils product by using the PDM compared the control
Similar results were also highlighted by other authors who have done similar research using the total destoner machine
University of Foggia, SAFE Dept.

13. Physiochemical characteristics of olive stone
In this slide you can see the physiochemical characteristics of olive stone obtained at the beginning of the extraction process by using the PDM and the olive stone obtained from the husk at the end of the process by using a husk destone machine.
The main differents are for the nitrogen and particle size less 1.4 mm. As you can see these two components are significantly smaller in the samples of the pits extracted by PDM.
For the nitrogen, a low content is better. After combustion, nitrogen is converted to nitrogen oxides (NOx), which represent the main environmental impact of biomass burning
For the fine particles is the same, a low content is better, infact fine particle leads uncontrolled combustions with consequent problems of emission.
For this reasons I can assert that the olive stone obtained from the PDM is better than the olive stone obtained at the end of the process by using the HDM.
University of Foggia, Department of the Science of Agriculture, Food and Environment

14. Conclusions
it is possible the use of a destoner machine in the oil extraction cycle, but is necessary that a part of olive stone (about 50%) continuous in the process
there is not losses of yields compared to the traditional crusher
the oils obtained contains more volatile compounds, green fruitiness notes, flavour and aroma than those obtained using the traditional crusher
there is a recovery of 12,5 kg of the pits from 100 kg of olives, as fuel and the pits is better quality compared the pits obtained from the pomace
there are no extra energy costs when the PDM is used respect to the traditional hammer crusher
University of Foggia, Department of the Science of Agriculture, Food and Environment

15. Papers
University of Foggia, Department of the Science of Agriculture, Food and Environment

16. Thanks for the attention
University of Foggia
Department of the Science of Agriculture, Food and Environment
Thanks for the attention
Prof. Alessandro LEONE