Introduction
The Spark spectral sensor makes a great choice for many emerging applications of spectroscopy including anti-counterfeiting of high value food ingredients such as olive oil. With the new Spark spectral sensing technology – a form of solid-state optical sensing comparable to a detector chip that functions as a spectrometer – Ocean Optics has developed a lightweight, compact spectral sensor that can be used as a stand-alone instrument, or integrated into an OEM device.
Spark has the sensing power to get rapid, meaningful results at incomparable value. With its small size, great speed and favorable pricing, the Spark is accessible to a wider range of research, process and OEM applications than similar devices. In this application note we use the Spark to measure counterfeit extra virgin olive oil, demonstrating Spark’s utility for detecting both dilution and adulteration of olive oil samples.
Background
The olive oil industry is thought to be worth around $11 billion annually (1). High quality extra virgin olive oil commands premium prices, making counterfeit oil products a real threat to the industry. This has been exacerbated in recent times as the industry’s largest producers, Spain and Italy, have had crops hit by drought and disease, resulting in diminished production. Confidence in product authenticity is important for consumers and businesses alike as adulterants and dilutions can affect quality and may even be harmful. Spectral analysis can be a surefire way discriminate true extra virgin olive oil from counterfeit products, which may otherwise look and even taste identical. In this application note, we use the Spark visible spectral sensor to explore the power of spectroscopy in distinguishing a number of oils and oil blends. We will show how the Spark can be used to identify different oils and to detect diluted extra virgin olive oil and cheap, low-grade oil made to look like extra virgin olive oil through the addition of chlorophyll -- a known counterfeiting technique (2), (3).
Determining the Authenticity of Olive Oil
Color is a great visual indicator of oil type, but it’s not always possible to tell oils apart just by looking at them. Color can be subjective and change under different lighting. Also, the color of oil can be artificially adjusted to replicate different qualities of oil. Plant pigments such as chlorophyll and beta-Carotene are known to be added to oils to imitate the characteristic darker color of extra virgin olive oil (2), (3). Taste testing is sometimes used, but this also lacks accuracy and can be costly.
Figure 1 - Four different types of oil are displayed here to demonstrate general distinctions among them as measured by the Spark spectral sensor. Each type of oil has a unique spectral shape determined by the organic compounds present in the oil.With spectral analysis using a device like Spark, more subtle differences among olive oil types can be discerned. Spectral analysis brings more accuracy to color measurements than the commonly used RGB sensor measurement technique. This is due to the extended range of wavelengths that are measured, giving more precise detail than a more limited number of wavelengths can achieve. Spectral differences among various olive oil samples are shown in Figure 1. Spectral sensing techniques reveal more sample detail and are more accurate than other measurement methods, and highlight distinctive differences even when sample color is very similar.
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