Bottling and Storing Our Olive Oil

Olive oil is prone to dramatic change in quality and palatability unless careful attention is given to general cleanliness and how the oil is bottled and stored. Incorrect storage practices influence the sensory quality of the oil, as it can become rancid and develop off-flavours. An excellent review of all aspects of packaging and storing of olive oil is by Piscopo and Poiana (2012) which can be downloaded here.

Piscopo and Poiana suggest that the ideal temperature for storing olive oil is 14-15C. Storage temperatures above 15C affect the quality of the oil.

Exposure to Oxygen in Air
Lipid oxidation is one of the factors which cause deterioration in olive oil quality. The rate of oxidation depends on the availability of oxygen, the presence of light, and storage temperature.

Exposure to Light and Bottle Materials
Light is detrimental to oil quality and accelerates oxidation. This is true of all light sources, including fluorescent lights in a storage environment.
Bottle Colour. A clear bottle might show off a pretty harvest-fresh colour, but it certainly will not protect the integrity of the oil from sunlight damage. Darker glass colours like amber, green, dark blue, or black are always preferable to clear glass from a quality point of view. One should care more about protecting the oil than seeing a fresh, green colour. Contrary to this, many studies have shown that the consumer is more likely to buy a product if they can actually see the content. This creates an obvious dilemma.
Bottle Material. The raw materials that are used to make the glass are of some importance, as glass can interact with whatever is stored in it. Some olive oil producers insist on using bottles that are certificated, particularly on lead content.
Ropp Tops. These are the metal or plastic twist tops that one finds on many bottled products. The defining characteristic of Ropp tops is that there is a tamper proof ring on the closure. When you first twist off the closure, you can hear it tear away from the lower portion and know that the bottle has not been opened since it was initially sealed. Ropp tops are extremely reliable closures and very resistant to pressure changes.

When to Bottle
Oil keeps better in stainless steel drums or tanks than in bottles, so bottling small quantities, only as much as needed, is a wise decision. Some large producers use drums topped with inert gas or tanks with floating lids to keep out light and minimise oxidation.

Our Bottling Method for Cottage Grove Oil

Our solution to bottling olive oil from the harvests in Cottage Grove was to purchase 1000 ml Amber sirop and black polying cap from Arthur Holmes Ltd in Petone. The Product Code is 1000sbpc, and they cost $70.10 plus GST per 20 bottle pack. These bottles are used for storing the olive oil for 12 months to allow all sediment to settle. It is important to make sure there is as little an air gap as possible above the oil to minimise oxidation during this storage period. These larger bottles were kept in a dark place in our garage. Although the temperature would not be the ideal 14-15C, it seldom falls below 10C in winter, and does not exceed 18C in summer.

After the 12 month settling period, the one litre bottles are decanted into their final containers. We use another product from Arthur Holmes Ltd. They are 500ml Marasca antique green bottle and black pourer tampertel cap. The Product Code is 500marpc, and they cost $39.25 plus GST for a pack of 24 bottles. Once again, the bottles should have the minimum air space above the oil. The caps need to be screwed down tight to ensure the pourer inside is fully seated.

As with the labels pasted on bottles of wine, it is customary to display a fashionable affectation of connoisseurship when describing one's olive oil on the label. While ours are no exception, the description on our label is purely whimsical. In addition, if anyone can find some more Cadet Piola please let us know. We are down to the last bottle of the 1983 vintage. We had our labels printed by Clutha Print in Balclutha at $143.75 (incl GST) per 100 (we supplied a pdf to print).