Detection of Food Fraud in high value products - Exemplary authentication studies on Vanilla, Black Pepper and Bergamot oil

The food label is providing information about the food's content and origin. Consumers rely on the trustworthiness of a given label, since the possibility to evaluate a product based on visual examination is often limited. Their buying decisions are therefore often influenced by the information and advertisement given on the food packaging. When a label is intentionally used to give the consumer an -apparently better- but misleading description of the food product, it is often done for economical gain. These cases of food fraud are called "economically motivated adulteration". The EU No. 1169/2011 provides the basis for a high level of consumer protection with respect to food information. Here, Art.7 clearly states that food information shall not be misleading. Beyond the consumer interest, food fraud is also a major issue in the trade chain from business to business: Fraud leads to an unfair competition and it furthermore includes a high risk for brand reputation. Analytical methods constitute an essential part of the strategies to fight food fraud. Suitable analytical methods must be applied to reveal food fraud and also to proof the authenticity of food products along complex supply chains. In this thesis, three different commodities, namely vanilla, black pepper and bergamot oil were investigated with respect to authentication by targeted as well as non-targeted analysis. Vanilla is one of the most popular flavours in the world. It is highly vulnerable to economically motivated adulteration as the main component vanillin can be derived by much cheaper production methods than by the extraction from vanilla pods. For an authentication testing of vanilla flavour, it is important to distinguish three categories: vanillin from vanilla pods, synthetic vanillin and natural biosynthetic vanillin also called biovanillin. Vanilla flavour can be sold in different variations, as vanilla pods, vanilla powder, vanilla extracts, pure vanillin or incorporated in composite food products. Each of these variations has different requirements and opportunities regarding the possible authentication testing of vanillin. This thesis provides an overview about different authentication testing methods of vanillin and their respective potential and limitations. One very often used indicator for the authenticity of vanillin is the analysis of the carbon isotope ratio of the vanillin molecule. The carbon isotope ratio values for synthetic or biosynthetic vanillin derived from petroleum and C3 plants can be distinguished from carbon isotope ratios range for vanillin from vanilla pods. In manuscript 1, an easy sample preparation procedure to determine the carbon isotope ratio of vanillin in complex food products by headspace solid-phase micro extraction and gas chromatography coupled to isotope ratio mass spectrometry is presented. The method was applied to 23 commercial food samples including vanilla sugar, dairy, and soy products, and some of these (22%) were highly suspicious to be fraud. However, the carbon isotope ratio value of the vanillin has some restriction as authentication parameter. In the last couple of years new biosynthetic pathways have been invented, which can produce biovanillin with a carbon isotopic ratio typical for vanillin from vanilla pods. The production of biosynthetic vanillin from glucose by yeast is the latest development. In manuscript 2, we present an isotopic characterisation of vanillin ex glucose by GC-IRMS. This is the first time, a 13C value for biovanillin is reported that is higher compared to vanillin from vanilla pods. The possibility to simulate the 13C range of vanillin from vanilla pods by combining vanillin derived from inexpensive sources constitutes an increased risk for fraud being perpetrated while remaining unnoticed. This study therefore also demonstrates that authentication strategies need to be dynamic and continuously adjusted to new market situations. Black pepper, the second commodity investigated in this thesis, is the most widely used spice in the world. Spices are highly vulnerable to economically motivated adulteration as they are high value products and traded along complex supply chains. The main fraud opportunity is to add cheaper bulking materials. Near and Fourier-Transform Infrared Spectroscopy has been combined with chemometrics to screen for the substitution of black pepper with papaya seeds, chili and with nonfunctional black pepper material such as black pepper husk, pinheads and defatted spent materials. This study, presented in manuscript 3, shows the huge potential for a fast and rapid screening method that can be used to both prove the authenticity of black pepper and detect adulterants. Finally, an authentication testing of bergamot oil by targeted analysis was conducted. Authentic and commercial bergamot oil samples have been analysed by chiral GC-MS analysis. The presence of synthetic compounds known to be used for adulteration of bergamot oil was checked in commercial bergamot oil samples. Based on this analysis, a high percentage (54%) of the commercial bergamot oil samples that were bought online were suspicious to be adulterated. Additionally, the GC-MS dataset was decomposed by parallel factor analysis 2 (PARAFAC2) and a first data evaluation approach using non-targeted analysis is presented. There is no magic solution for authenticity testing, but powerful detection tools are available. It will be a continuous task to find the methods that are suitable for an effective control along the food supply chains. Even though it is an unrealistic aim to detect every single adulterated product, analytical detection methods can very efficiently contribute to a general deterrence strategy that puts every fraudster on a significant risk of being apprehended. With the same strategy, seriously operating companies can be protected from brand risk and unfair competition.