The Impact of Packaging on the Quality of Extra Virgin Olive Oil

Extra virgin olive oil (*EVOO- extra virgin olive oil) is a highly valued product for its health benefits. Rich in polyphenols and unsaturated fats, it is considered one of the healthiest fats available on the market. However, the quality and safety of olive oil largely depend on storage conditions, and choosing the right packaging is crucial. In this article, we will discuss the impact of various packaging types on olive oil quality, the risks associated with Bisphenol A (BPA), and alternative solutions like modern bag-in-box packaging, glass, and stainless steel, which better protect extra virgin olive oil.

 

Why are plastic packages harmful?

Plastic packaging used for storing extra virgin olive oil contains chemical substances, the most dangerous of which is Bisphenol A (BPA). BPA is a chemical compound used in the production of plastic and epoxy resins, found in many everyday products like water bottles and food containers. BPA can migrate into food, especially when exposed to heat, which leads to the deterioration of both the taste and health properties of the product. Very often, olive oil sold in plastic containers labeled as extra virgin is no longer extra virgin due to temperature and UV exposure leading to degradation. If you decide to purchase olive oil in such packaging, be sure to check for the "BPA-free" label. This designation may also be shown graphically. It’s advisable to transfer the product to proper containers as early as possible and ensure it is stored correctly.

Health risks associated with BPA

BPA acts like a synthetic hormone, mimicking estrogen, which can lead to hormonal imbalances, negatively affecting the reproductive system and metabolic functions. High exposure to BPA can increase the risk of hormonal diseases, such as infertility, thyroid issues, and even certain types of cancer, including breast and prostate cancer. In infants and children, BPA can negatively impact brain development and the immune system.

Does olive oil react with plastic packaging?

A bit of theory

Extra virgin olive oil has acidity, but this does not mean it is an acid in the traditional chemical sense, like citric or acetic acid. Acidity in olive oil refers to the free fatty acid content, mainly oleic acid, and is a measure of the oil's quality. This value represents the percentage of free fatty acids that can form as a result of triglyceride degradation. Essentially, the lower the acidity, the higher the oil's quality. According to international standards, extra virgin olive oil must have an acidity level below 0.8%. Low acidity indicates that the oil is fresh and made from cold-pressed olives without chemical processes. Importantly, acidity is measured immediately after harvest, and improper storage before bottling can cause it to rise drastically. In addition to appropriate acidity, for olive oil to be classified as extra virgin, the defect median (indicating flavors or aromas that point to oil defects, such as fermentation, rancidity, or mustiness) must be 0. This means the oil must not have any sensory defects. Extra virgin olive oil should have positive attributes with a median score higher than 1:

Fruity: Extra virgin olive oil should exhibit the positive attribute of fruitiness. This is the aroma of fresh olives, which can be intense, medium, or mild, depending on the type of olives. The scale ranges from 1-10 (or 1-6). Fruitiness is determined by standard methods and can be assessed at home, with a score indicating the strength of the aroma.
Bitterness: The bitter taste is a natural attribute of oil made from unripe olives.
Pungency: The spicy flavor is another indicator of freshness and is due to the presence of polyphenols, which have antioxidant and anti-inflammatory properties.

 

Positive aroma attributes include: Fresh almond, fresh apple, artichoke, chamomile flowers, citrus fruits (flowers, orange, bergamot, tangerine, grapefruit), eucalyptus leaves, exotic fruits (pineapple, banana, passion fruit, mango, papaya, medlar), fig leaf, flowers or floral notes, grasses, green pepper, green, green fruity, herbs, fresh olive leaf, fresh pear, fresh pine core, fresh pineapple, soft fruits (blackberries, raspberries, blueberries, bilberries), sweet paprika, tomato leaves, vanilla, and walnut.

All these characteristics are evaluated by a sensory panel, which classifies olive oil based on tasting results and biochemical analysis.

See how the sensory evaluation of olive oil is conducted by a sommelier panel (Berlin GOOA competition).

Though extra virgin olive oil is not a strong acid, plastic packaging can still negatively impact its quality. Plastic can react with the fats in the olive oil, especially under high temperatures, such as during transport or exposure in stores or markets. Several factors can cause chemical substances from plastic to migrate into the olive oil, affecting the product's safety and quality. High temperatures can accelerate chemical processes, increasing the risk of chemical migration from the packaging into the olive oil. Plastic containers, especially those containing BPA, are particularly prone to this issue. The longer the olive oil remains in contact with plastic packaging, the greater the risk of harmful chemicals leaching into the oil. Free fatty acids in the oil can accelerate this process. Some plastics, particularly those containing BPA, can react with the fats in the olive oil. BPA, like other chemicals used in plastic production, can migrate into food, especially when the packaging is exposed to high temperatures or when it contains fatty products like olive oil.

Can chemical reactions occur in plastic packaging?

Yes, while olive oil is not a strong acid, there is still a risk of chemical reactions when stored in plastic packaging, especially those made from materials containing BPA or other chemicals. The oxidation of fats in the oil and the interaction between the plastic and fats can lead to harmful substances migrating into the oil, degrading its quality and posing health risks to consumers.

How to prevent olive oil degradation in plastic packaging?

To avoid these problems, it is best to store olive oil in packaging made from safe materials, such as glass, stainless steel, or bag-in-box packaging, which minimizes air contact and does not contain BPA.

What are the alternatives?

There are safer and more effective ways to store extra virgin olive oil that not only protect its properties but also the health of consumers. Here are a few alternative solutions:

Glass – the best choice

Glass bottles with UV filters are one of the best packaging options for extra virgin olive oil. Glass completely eliminates the risk of BPA migration into the product, and dark glass further protects the oil from UV rays that accelerate oxidation processes. These types of packaging are especially recommended for long-term olive oil storage. A very important element is the cap, and the most secure (and also the most expensive for producers) is a special anti-oxidation cork, or a natural cork from cork oak. Some producers also use nitrogen to fill each bottle, creating a protective barrier against air.

Stainless steel – durability and protection

Stainless steel containers are popular for storing extra virgin olive oil due to their durability and resistance to light. While steel protects olive oil from sunlight, containers may have some limitations related to oxidation if too much air remains in the container. Nevertheless, stainless steel is a safe solution, particularly when containers are designed with low oxygen permeability.

Bag-in-Box – a modern solution

Bag-in-box packaging consists of multi-layered bags placed inside a cardboard box. They minimize the contact of the oil with air, slowing the oxidation process. This packaging is becoming increasingly popular because it effectively protects the oil from degradation.

Research conducted by the University of Ioannina in Greece showed that extra virgin olive oil stored in bag-in-box packaging maintained its properties for 120 days at room temperature (22°C) and 100 days at elevated temperatures (37°C). In comparison, olive oil stored in traditional steel containers lost its properties after 80 days at room temperature and after 60 days at elevated temperatures.

The research findings were published in the study “Effect of bag-in-box packaging material on quality characteristics of extra virgin olive oil stored under household and abuse temperature conditions” by A. Lolis, A.V. Badeka, M.G. Kontominas, from the Laboratory of Food Chemistry, Department of Chemistry, University of Ioannina, Ioannina, Greece.

Purpose and scope of the research

The study aimed to compare the impact of bag-in-box (B) packaging with traditional tinplate (S) containers on the quality of extra virgin olive oil under two different storage conditions:

• 22°C – room temperature, simulating household conditions.
• 37°C – elevated temperature, simulating extreme storage conditions.

The analysis included various quality parameters of the oil, such as acidity, peroxide value (PV), absorption coefficients K232 and K270, polyphenol content (TPC), and the volatile compounds profile. The goal was to determine which packaging better protects EVOO from degradation in both temperatures.

Methodology

Olive oil samples

The olive oil samples came from the Peza Union of Agricultural Cooperatives in Crete, and the oil was produced from Koroneiki olives harvested between October and December. The olive oil was processed within 24 hours of harvesting.

Sample preparation and storage conditions

The samples were packed in two types of packaging:

• Bag-in-box (B): Multi-layered bags placed in cardboard boxes. These bags had low oxygen permeability (<0.5 mL O2/m²·24 h·atm).
• Steel containers (S): Traditional tinplate containers used for storing olive oil.

The samples were stored for 120 days, with analysis conducted every 20 days. The two storage conditions included:

• 22°C: Simulating normal household conditions.
• 37°C: Simulating extreme storage conditions.

Quality parameters

The following quality parameters of the olive oil were analyzed:

• Acidity (% oleic acid): A quality indicator of olive oil; extra virgin olive oil must have an acidity below 0.8%.
• Peroxide value (PV) (meq O2/kg): Measures the level of peroxides, which are oxidation products of fats.
• Absorption coefficients K232 and K270: Used to assess oxidation levels. K232 measures primary oxidation products, and K270 measures secondary oxidation products.
• Total polyphenol content (TPC) (mg/L): Polyphenols are natural antioxidants that protect the oil from oxidation.
• Volatile compound profile: Volatile compounds such as aldehydes, alcohols, and ketones affect the aroma of the oil. Their increase may indicate oxidation.

Analytical methods

• Acidity, peroxide value, K232, and K270: Measured according to official methods described in the EEC/2568/91 regulation of the European Commission.
• Volatile compounds: Analyzed using solid-phase microextraction (SPME) combined with gas chromatography-mass spectrometry (GC/MS).
• Polyphenols: Measured using spectrophotometric methods.
• Olive oil color: Measured using a colorimeter, which recorded the parameters L* (brightness), a* (greenness/redness), b* (yellowness/blueness).

Statistical analysis

The results were subjected to statistical analysis using two-way analysis of variance (ANOVA), and the significance of differences was tested using the LSD test.

Results

Acidity

Olive oil stored in steel containers (S) at 22°C exceeded the permissible acidity level (0.8%) after 100 days, and at 37°C, after 60 days.

Olive oil stored in bag-in-box (B) maintained acidity below 0.8% for the entire storage period at room temperature, and in elevated temperatures, up to 100 days.

Conclusions: Bag-in-box packaging more effectively protects olive oil from increasing acidity, indicating slower degradation compared to steel containers, especially at higher temperatures.

Peroxide value (PV)

Results: Olive oil in steel containers exceeded the permissible PV level (20 meq O2/kg) after 100 days at 37°C, while olive oil in bag-in-box maintained PV levels below this limit throughout the storage period.

Conclusions: Bag-in-box packaging better protects olive oil from oxidation, which is crucial for maintaining EVOO quality.

Absorption coefficients K232 and K270

Results: Olive oil stored in steel containers at 37°C exceeded the K232 limit after 80 days, and the K270 limit after 120 days. Olive oil in bag-in-box maintained K232 and K270 values below the threshold limits throughout the storage period.

Conclusions: Bag-in-box offers better protection against oxidation compared to steel containers.

Polyphenol content (TPC)

Results: At room temperature, polyphenol content in olive oil decreased by 22.7% (bag-in-box) and 23.5% (steel containers). At higher temperatures, the decrease was 27.7% (bag-in-box) and 34% (steel).

Conclusions: Bag-in-box packaging better preserves polyphenol content, indicating better protection against oxidative degradation.

Volatile compound profile

Results: At 37°C, higher concentrations of volatile compounds such as heptanal, octanal, and nonanal were observed in samples stored in steel containers. Olive oil in bag-in-box had significantly lower concentrations of these compounds, indicating slower degradation.

Conclusions: Bag-in-box packaging more effectively protects EVOO from the formation of volatile compounds related to oxidation, allowing for a longer retention of fresh olive oil aroma.

Olive oil color

Results: At 37°C, greater color changes were observed in samples stored in steel containers than in bag-in-box packaging. The reduction in green color intensity was more pronounced in steel containers.

Conclusions: Color changes indicate greater degradation in steel containers, while olive oil in bag-in-box better maintained its visual characteristics.

Overall conclusions

Bag-in-box packaging offers superior protection for EVOO compared to steel containers, particularly at higher temperatures. Olive oil stored in bag-in-box retained its extra virgin quality for a longer period under both household and extreme conditions.

Steel containers were less effective at preventing olive oil degradation, shortening the shelf life of the oil while maintaining its quality.

The study suggests that for long-term storage of extra virgin olive oil in household and elevated temperature conditions, bag-in-box is a better choice than traditional steel containers.

Research conducted by the University of Ioannina in Greece demonstrated that olive oil stored in bag-in-box packaging was better protected from oxygen exposure than in steel containers. As a result, oxidation processes occurred more slowly, leading to a longer freshness period and better quality. The study showed that polyphenol content in olive oil stored in bag-in-box decreased by 27.7% after 120 days, while in steel containers, the decrease was 34%.

Thanks to the multi-layered structure of the bags, which minimize the contact of olive oil with air, bag-in-box packaging ensures longer shelf life and better preservation of the health properties of extra virgin olive oil.

Examples of Bag-in-Box Products

• ABEA Kolymvari Chania PDO BAG in BOX 5L – Olive oil in 5L Bag-in-Box packaging, which perfectly protects the oil from light and oxygen.
• KALI Blend Toscano Italy PGI 3L BIO – High-quality organic olive oil in 3L Bag-in-Box packaging, which perfectly protects the oil from light and oxygen.
• Wild Groves Foxy COOC 750ml – Exceptional olive oil from California, available in convenient 750ml Bag-in-Box packaging.

Summary

Extra virgin olive oil is a product that requires proper storage to retain its health and flavor properties. Plastic packaging, especially those containing BPA, poses a real health risk, especially at high temperatures. To minimize the risk of harmful substance migration, it's best to choose olive oil in glass bottles, stainless steel containers, or bag-in-box packaging. These solutions not only guarantee higher product quality but also protect our health.

Sources:

Effect of bag-in-box packaging material on quality characteristics of extra T virgin olive oil stored under household and abuse temperature conditions
A. Lolis, A.V. Badeka, M.G. Kontominas⁎ Laboratory of Food Chemistry, Department of Chemistry, University of Ioannina, Ioannina, 45110, Greece

National Institute of Environmental Health Sciences Bisphenol A (BPA) is a chemical produced in large quantities for use primarily in the production of polycarbonate plastics and epoxy resins. NIEHS and NTP support research to better understand potential health effects of exposure to BPA.

Multichrome lab

International Olive Council

Compiled and translated by: Tadeusz Gruszczyński certified olive sommelier. Copying without the author’s permission is prohibited.