1. Avocado Oil – The Colour of Quality
Marie Wong, Ofelia Ashton, Tony McGhie, Cecilia Requejo-Jackman, Laurence Eyres, Nimma Sherpa, Allan Woolf
Institute of Food, Nutrition & Human Health, Massey University, Private Bag , Auckland, New Zealand
The Horticulture & Food Research Institute of New Zealand, Mt Albert Research Centre, Private Bag , New Zealand
Oil and Fats Group, NZ Institute of Chemistry, PO Box , Auckland, New Zealand

2. Avocado Persea americana Mill.
Originally from Central America and Southern Mexico
Persea americana Mill.
‘Hass’ variety is the main variety grown in NZ and USA
‘Hass’ have a small stone and are thin skinned (green  purple/black)
Flesh is smooth and buttery
Oil content can reach >30% of fresh weight

3. Fruit Development
% Dry matter is highly correlated to fruit oil content.
% Dry matter used as key maturity index
Harvest only when minimum dry matter is reached (17 – 25%)
Avocado fruit do not ripen until harvested

4. Fruit Ripening Fatty acid profile does not change
Fruit softening occurs
Texture and flavour changes
Skin changes colour from green to purple/black

5. Colour changes in the skin and flesh

6. Colour changes in the skin and flesh

7. Anthocyanin changes in the skin

8. Pigment changes in skin and flesh with ripening - Carotenoids

9. Pigment changes in skin and flesh with ripening - Carotenoids
Carotenoids identified in skin and flesh
Skin
Concentration (g/g FW)
Dark green flesh
Lutein
20.5
Neoxanthin
1.7
-Carotene
12.5
5.5
Violaxanthin
1.1
4.5
Zeaxanthin
0.4
-Carotene
3.9
0.3
Antherxanthin 1
0.1
0.9
Day 2 values

10. Pigment changes in skin and flesh with ripening - Chlorophylls

11. Pigment changes in skin and flesh with ripening - Chlorophylls

12. Pigment changes in skin and flesh with ripening - Chlorophylls
Chlorophylls identified in skin and flesh
Skin
Concentration (g/g FW)
Dark green flesh
Chlorphyllide a
135.8
Chlorophyll a
23.0
Chlorophyllide a
6.5
Chlorophyllide b
13.9
Chlorophyll b
5.3
8.6
0.2
Pheophytin a
0.1 nd
Pheophytin b
0.05
Day 2 values

13. Cold Pressed Avocado Oil
Started in NZ commercially
No significant processing
Centrifuge at low temperature
Emerald green
Distinctive avocado flavour
Higher health
Used for culinary purposes mainly

14. The Cold Press Extraction Process
Avocado fruit
Water wash
De-stoner
Skin & stones
Grinder
Water
Avocado paste
Paste mixer (Malaxer)
Decanter
Pomace
Waste water
Centrifuges
Extra virgin oil
Oil storage tank
Bottling

15. The Cold Press Extraction Process
Avocado fruit
Water wash
De-stoner
Skin & stones
Grinder
Water
Avocado paste
Paste mixer (Malaxer)
Decanter
Pomace
Waste water
Centrifuges
Extra virgin oil
Oil storage tank
Bottling

16. The Cold Press Extraction Process
Avocado fruit
Water wash
De-stoner
Skin & stones
Grinder
Water
Avocado paste
Paste mixer (Malaxer)
Decanter
Pomace
Waste water
Centrifuges
Extra virgin oil
Oil storage tank
Bottling

17. The Cold Press Extraction Process
Avocado fruit
Oil Extraction Yield Dependent On:
maturity at harvest
degree of ripeness
time of season
variety
Water wash
De-stoner
Skin & stones
Grinder
Water
Avocado paste
Paste mixer (Malaxer)
Decanter
Pomace
Waste water
Centrifuges
Extra virgin oil
Oil storage tank
Bottling

18. The Cold Press Extraction Process
Avocado fruit
Maintaining Oil Colour
minimise degradation of chlorophyll
eliminate light
eliminate oxygen
Water wash
De-stoner
Skin & stones
Grinder
Water
Avocado paste
Paste mixer (Malaxer)
Decanter
Pomace
Waste water
Centrifuges
Extra virgin oil
Oil storage tank
Bottling

19. Colour of cold pressed avocado oil
Lightness
88  100?
Chroma
11 15
Hue
168  227
a* (green (-) red (+))
-5  -0.7
b* (blue (-)  yellow (+))
-1.2  9.3
Lab trials varying level of skin

20. Pigments in the cold pressed avocado oil
g / g oil
Chlorophyll compounds
Chlorophyll a
Chlorophyll b
2.7 – 5.1
Pheophytin a
Pheophytin b
Total chlorophyll (by spectrophotometer)
14.5 – 18.5
Carotenoid compounds
Lutein
1.6 – 1.9
Antherxanthin
Neoxanthin
<0.1 – 0.3
Violaxanthin
<0.1
Zeaxanthin
Data from Table 5.3 only 5% factory Day 0 – day 97 20, 4, -20C in dark

21. Influence of skin level on pigment levels in oil –laboratory scale

22. Influence of skin level on oil colour –laboratory scale

23. Influence of storage on colour and pigments in oil
Approx. 5% skin in paste during malaxing
Stored in dark brown bottles
Nitrogen sparged before sealing
Stored at 4, 20 and 50oC in dark
Stored at 20oC in light

24. Influence of storage on colour of oil

25. Influence of storage on pigments and stability

26. Key points Colour is important for the quality of avocado oil
High chlorophyll pigment level contributes to the green colour
Extraction process important for maintaining pigment levels
Extraction of more pigments- beneficial?
Minimise the degradation of pigments
Pigments and oxidative stability
Chlorophyll is light sensitive
Loss of chlorophyll leads to loss of green colour
Bottle under low light – brown bottles, reduce oxygen

27. Future Considerations
Currently avocado oil is not produced to achieve a desired colour, oxidative stability more important.
Pigments in avocado oil – other cultivars
Pigments in avocado – health benefits

28. Acknowledgements
Funding
FRST (NZ government)
TechNZ
Olivado NZ Ltd