**5.2. Olive oil packaging materials**

208 Olive Germplasm – The Olive Cultivation, Table Olive and Olive Oil Industry in Italy

present.

properly.

**5. Packaging of olive oil** 

**5.1. Olive oil packaging method** 

the containers intended for olive oil clarification.

As the extra virgin olive oil extraction is conducted with controlled temperatures lower than 28 °C, as the extra virgin olive oil storage requests the same attention. It has to be done with control of temperature, which may range from 10 °C to 18 °C: the correct storage temperature is 14-15 °C. The high temperatures increase the chemical variation velocity and the major oil fluidity. This last effect promotes the oxygen permeation. When storage temperature decreases at 8-9 °C, white deposits can appear in the oil, due to triglyceride crystallization. The higher is the content of saturated glycerides, the higher is the freeze process. The step from the oil crystallization to the solidification by lower temperatures (3-4 °C) slightly increases the oil stability to the oxidation and gives substantial modifications in the sensory profile. If the clear colour maintains beside the transfer of solidified oils to warmer places, it possible that a margarinization process involved or mucilage could be

Finally, it is important that storing and packaging facilities respect hygiene and healthiness standards. Aromatic polycyclic hydrocarbons and benzene present in the atmosphere are

After olive pressing, oils are transferred in tanks and after pouring they are put into storage containers where they attain their sensory characteristics. Containers are of different materials and capacity ; they are made mainly with AISI 304 inox steel which is also used for

The packaging in the selling container is the last unit operation: it is very important for product stability, maintaining high quality level and also value added, if carried out

Reduction of oxygen in the packaging headspace and light exposure are key factors in lowering lipid oxidation and off-flavour development, thus keeping quality of olive oil.

The Regulation 1019/2002/CE (Official Journal European Union, 2002) sanctioned the prohibition of the consumer sale of the on tap olive oils. This effect promotes the consumer protection in product quality and the valorisation of farm identity. In this sense olive farms can provide packaging or ask for it to external companies. As for the other foods, the oil storage and packaging mill area must be maintained clean, ventilated, illuminated and all the unit operations should follow the hygienic-health rules according to Regulation 852/2004/CE (Official Journal European Union, 2004). As previously discussed, olive oil must be stored at constant temperature, about 14-15 °C, protected from light and air. When oils are stored in big containers (inox steel is the best material), these have to be preferably

For smaller quantities, the bottling with depression and the pre-bottling with inert gas are nowadays diffused by using bottlers apparatus , which saturate the headspace with nitrogen

maintained quite full or better with the headspace filled with nitrogen..

absorbed by the oils contained in not hermetically sealed packages (Ricci, 2007).

In Italy and in the world the majority of consumers purchases bottled olive oil. Nowadays attention of many actors is focused on olive oil packaging, in particular on container design that often communicates the natural concept and territory link associated to the contained olive oil. Due to the changed life-style, oil container manifests also a functional property.

The nature of the packaging material has a notable influence on oil quality (Gutierrez et al., 1988). In general, a packaging is chosen depending on several criteria as product stability, environmental conditions to which food will be exposed during storage and distribution, and the product nature. In particular, the basic factors that may alter the quality of packed oils are:

	- Dissolved oxygen in the oil, that is the oxygen that remains in the container free space after it is sealed and the oxygen diffused through the walls

Packaging and Storage of Olive Oil 211

conducted on olive oil shelf life attested the glass as the best material for the storage (Pristouri et al., 2010), especially when oil was stored in the dark (Kanavouras et al., 2004), and for its acidity and peroxide value, with respect to other packages (Rababah et al., 2011). Finally, in a comparative study among glass, High Density Polyethylene (HDPE) and PET, results clearly indicated the glass was the best in the following ranking Glass > HDPE > PET

First uses of this material date back to 1700 in domestic environment. Steel is an iron/carbon

The tinplate is a sheet of soft steel, which is more workable because of its lower carbon content, coated on both faces by tin oxides layers and on face destined to the contact with food also by organic synthetic lacquers. Tinplate container is mainly of rectangular shape; its side seam is welded and protected with a food-approved special varnish: the welding method assures a secure side seam, avoiding the dissolution of lead into the product (Tsimis

The inox steel is an alloy containing 11% of chrome which reacts with oxygen originating an autopassivation condition due to the chrome oxides presence (Piergiovanni & Limbo, 2010). It is the best material for the preservation of big volumes of olive oil. Compared to glass, it has the same water resistant properties (so protects the product from oxygen, humidity and microrganisms), and major advantages, e.g. handless, cleanness, shock resistance and total

A research of Grover (1982) demonstrated that the quality of oils decreases if packed in reused tinplate containers, whereas new containers did not alter oils during the one year storage period. A more recent study confirmed that the storage of oils in stainless and dark glass appears more adequate, with respect to other packaging materials, as clear PET and

(Ben Tekaya et al., 2007).

*5.2.2. Steel and tinplate* 

& Karakasides, 2002).

light protection.

clear glass (Dabbou et al., 2011).

**Figure 1.** Several types of commercial glass bottles for olive oil.

alloy: the higher the carbon percentage, the higher the rupture limit.


The principal used materials for olive oil packaging are represented by glass, steel, tinplate and, in Italy to a lesser degree, plastic and polycoupled ones.

### *5.2.1. Glass*

Glass represents an ancient material used in container structure: first glass containers derived by rocks date back to 3000 BC. It is formed principally by silica obtained by sand, flint or quartz. Silica is fused at very high temperatures (about 1720 °C) to form silicated glass. In most cases, silica is mixed with variable proportions to several raw materials: e.g. sodium and potassium carbonates (which act as stabilizer and protect the glass from the water solubilisation), lead (which confers transparency and lightness) and aluminium (which increases its hardness and lastingness). Glass is neither in a solid nor in a liquid state but glassy. Its molecules are arranged in disarray but with a sufficient cohesion to give mechanical stiffness. The structural basic unit is represented by the silica-oxygen tetrahedron, in which a silica atom is surrounded by four oxygen atoms to form a tetrahedron. Big groups tend to dispose with disorder (amorphous structure) giving the glass fragile with the tendency to rupture if submitted to an excessive tension. This induces effects on its thermal resistance that is function of container type, packaging faces and exposed surface to tension (internal if warmed and external if cooled) (Robertson, 2009).

In Italy glass is the king container for the olive oil packaging. Glass bottles can have different forms and capacities and their colour can vary largely from white to green and more dark tints. In Figure 1 several size of glass bottles are presented to demonstrate the large offer in the Italian olive oil market also of aromatized oils with spices or hot pepper.

From an Italian research about the most diffused containers, 64%of olive farms use the green glass whereas only the 10% of the total chooses the transparent one (Ricci, 2007). The best containers for the olive oil are made in opaque and dark glass: it is advisable to prefer very dark ones because little light can pass through. Since the consumer appreciates also the light glass because it is transparent and so shows the oil colour, then it is advisable to supply the bottle with a paper case which can protect the product by light. Guil-Guerriero and Urdo Romacho (2009) reported a shelf life study carried out on oils produced from *Picual*, *Hojiblanca* and *Arbequina* cultivars packaged in dark and transparent glass bottles. These oils showed an increase in some parameters; the variation of peroxide value was significant in extra virgin olive oils stored in transparent glass. Similar results were observed by Del Caro et al. (2006) and Vacca et al. (2006) on *Bosana* extra virgin olive oils. Several studies conducted on olive oil shelf life attested the glass as the best material for the storage (Pristouri et al., 2010), especially when oil was stored in the dark (Kanavouras et al., 2004), and for its acidity and peroxide value, with respect to other packages (Rababah et al., 2011). Finally, in a comparative study among glass, High Density Polyethylene (HDPE) and PET, results clearly indicated the glass was the best in the following ranking Glass > HDPE > PET (Ben Tekaya et al., 2007).

**Figure 1.** Several types of commercial glass bottles for olive oil.
