Detection of hazelnut oil in extra-virgin olive oil by analysis of polar components by micro-solid phase extraction based on hydrophilic liquid chromatography and MALDI-ToF mass spectrometry

Research advances in detection of food adulteration and application of MALDI-TOF MS: A review

Food adulteration and illegal supplementations have always been one of the major problems in the world. The threat of food adulteration to the health of consumers cannot be ignored. Food of questionable origin causes economic losses to consumers, but the potential health risks cannot be ignored. However, the traditional detection methods are time-consuming and complex. This review mainly discusses the types of adulteration and technologies used to detect adulteration. Matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS) is also emphasized in the detection of adulteration and authenticity of origin analysis of various types of food (milk, meat, edible oil, etc.), and the future application direction and feasibility of this technology are analyzed. On this basis, MALDI-TOF MS was compared with other detection methods, highlighting the advantages of this technology in the detection of food adulteration. The future development prospect and direction of this technology are also emphasized.

Exploring Strategies to Mitigate the Lightness Effect on the Prediction of Soybean Oil Content in Blends of Olive and Avocado Oil Using Smartphone Digital Image Colorimetry

Extra virgin olive oil (EVOO) and avocado oil (AVO) are recognized for their unique sensory characteristics and bioactive compounds. Declared blends with other vegetable oils are legal, but undeclared mixing is a common type of fraud that can affect product quality and commercialization. In this sense, this study explored strategies to mitigate the influence of lighting in order to make digital image colorimetry (DIC) using a smartphone more robust and reliable for predicting the soybean oil content in EVOO and AVO blends. Calibration models were obtained by multiple linear regression using the images' RGB values. Corrections based on illuminance and white reference were evaluated to mitigate the lightness effect and improve the method's robustness and generalization capability. Lastly, the prediction of the built model from data obtained using a distinct smartphone was assessed. The results showed models with good predictive capacities, R2 > 0.9. Generally, models solely based on GB values showed better predictive performances. The illuminance corrections and blank subtraction improved the predictions of EVOO and AVO samples, respectively, for image acquisition from distinct smartphones and lighting conditions as evaluated by external validation. It was concluded that adequate data preprocessing enables DIC using a smartphone to be a reliable method for analyzing oil blends, minimizing the effects of variability in lighting and imaging conditions and making it a potential technique for oil quality assurance.

MALDI-TOF Mass Spectrometry Applications for Food Fraud Detection

Chemical analysis of food products relating to the detection of the most common frauds is a complex task due to the complexity of the matrices and the unknown nature of most processes. Moreover, frauds are becoming more and more sophisticated, making the development of reliable, rapid, cost-effective new analytical methods for food control even more pressing. Over the years, MALDI-TOF MS has demonstrated the potential to meet this need, also due to a series of undeniable intrinsic advantages including ease of use, fast data collection, and capability to obtain valuable information even from complex samples subjected to simple pre-treatment procedures. These features have been conveniently exploited in the field of food frauds in several matrices, including milk and dairy products, oils, fish and seafood, meat, fruit, vegetables, and a few other categories. The present review provides a comprehensive overview of the existing MALDI-based applications for food quality assessment and detection of adulterations.

Olive oil authentication: A comparative analysis of regulatory frameworks with especial emphasis on quality and authenticity indices, and recent analytical techniques developed for their assessment. A review

Over the last decades, olive oil quality and authenticity control has become an issue of great importance to consumers, suppliers, retailers, and regulators in both traditional and emerging olive oil producing countries, mainly due to the increasing worldwide popularity and the trade globalization of this product. Thus, in order to ensure olive oil authentication, various national and international laws and regulations have been adopted, although some of them are actually causing an enormous debate about the risk that they can represent for the harmonization of international olive oil trade standards. Within this context, this review was designed to provide a critical overview and comparative analysis of selected regulatory frameworks for olive oil authentication, with special emphasis on the quality and purity criteria considered by these regulation systems, their thresholds and the analytical methods employed for monitoring them. To complete the general overview, recent analytical advances to overcome drawbacks and limitations of the official methods to evaluate olive oil quality and to determine possible adulterations were reviewed. Furthermore, the latest trends on analytical approaches to assess the olive oil geographical and varietal origin traceability were also examined.

Identification of protein markers for the occurrence of defrosted material in milk through a MALDI-TOF-MS profiling approach

Mozzarella di Bufala Campana is a soft, stretched curd Italian cheese made from fresh buffalo milk that obtained the Protected Designation of Origin (PDO) registration in EU legislation. Seasonality of buffalo milk production, rapid cheese decay and transport of its preserving liquid have relevant practical/economic consequences for mozzarella production; consequently, a progressive diffusion of cheese products realized with frozen curd or frozen milk has recently been observed. In order to meet the demand of the dairy producers and consumers for a reduction of starting material adulterations and for the certification of the raw milk used for cheese manufacturing, we have developed a rapid/robust MALDI-TOF-MS polypeptide profiling procedure that assays material quality through the identification of specific markers of its freshness. Massive analysis of fresh and frozen buffalo milks (stored for different times) was realized to this purpose; a tough statistical evaluation of the resulting data ultimately permitted the typing of milk samples. We identified 28 polypeptide markers of the milk freezing storage, among which 13 and 15 showed down- and over-representation, respectively. Quantitative data were confirmed by an independent analytical approach on selected markers. GLYCAM1-derived phosphopeptides (1-53), β-casein-derived phosphopeptides (1-68), β-casein-derived γ2-, γ3- and γ4-fragments, α-lactalbumin and β-lactoglobulin were components showing the highest significance. The occurrence of the first compounds in buffalo milk is here described for the first time; their formation in the frozen material was ascribed to the activity of plasmin or of unknown bacterial proteases/peptidases stable at low temperatures. In conclusion, data reported here suggest the application of this MALDI-TOF-MS polypeptide profiling platform to other high-quality dairy productions, in which milk freshness has important consequences on final product organoleptic properties.

BIOLOGICAL SIGNIFICANCE

In the last decades, several studies have provided the molecular basis underlying the relation between food quality and human wellness/health. In this context, Foodomics emerged as a novel scientific discipline studying food and nutrition domains through the application of advanced omics technologies, including genomics, transcriptomics, proteomics and/or metabolomics. Above-mentioned technologies have been used in an integrated, holistic way to study foods for: i) compound profiling, authenticity, and/or biomarker-detection related to product quality or safety; ii) contaminants and their whole toxicity; iii) bioactivity and general effects on human health; iv) their digestion and assumption in human body; v) development of new transgenic products; and vi) evaluation of their modifications within the digestive tract. In the first context, a highly reproducible MALDI-TOF-MS polypeptide profiling procedure is here presented, which provides information on buffalo milk quality through the identification of specific markers of its freshness. Among identified markers, some were indicative of the action of various proteolytic enzymes and the resulting occurrence of specific defense components in buffalo milk having the physiological role to limit bacterial/virus content in this biological fluid. Data suggest the possible application of similar MALDI-TOF-based platforms to other high-quality food productions, where storage conditions of the starting materials may have important consequences on final product characteristics.

A Simple and Effective Mass Spectrometric Approach to Identify the Adulteration of the Mediterranean Diet Component Extra-Virgin Olive Oil with Corn Oil

Extra virgin olive oil (EVOO) with its nutraceutical characteristics substantially contributes as a major nutrient to the health benefit of the Mediterranean diet. Unfortunately, the adulteration of EVOO with less expensive oils (e.g., peanut and corn oils), has become one of the biggest source of agricultural fraud in the European Union, with important health implications for consumers, mainly due to the introduction of seed oil-derived allergens causing, especially in children, severe food allergy phenomena. In this regard, revealing adulterations of EVOO is of fundamental importance for health care and prevention reasons, especially in children. To this aim, effective analytical methods to assess EVOO purity are necessary. Here, we propose a simple, rapid, robust and very sensitive method for non-specialized mass spectrometric laboratory, based on the matrix-assisted laser desorption/ionization mass spectrometry (MALDI-TOF MS) coupled to unsupervised hierarchical clustering (UHC), principal component (PCA) and Pearson's correlation analyses, to reveal corn oil (CO) adulterations in EVOO at very low levels (down to 0.5%).

Determination of hidden hazelnut oil proteins in extra virgin olive oil by cold acetone precipitation followed by in-solution tryptic digestion and MALDI-TOF-MS analysis

Adulteration of extra-virgin olive oil (EVOO) with hazelnut oil (HO) is an illegal practice that could have severe health consequences for consumers due to the possible exposure to hidden hazelnut allergens. Here, matrix-assisted laser-desorption/ionization (MALDI) mass spectrometry (MS) was used as a rapid and sensitive technique for the detection of a low concentration of hazelnut proteins in oil samples. Different protocols were tested for protein extraction, and the most efficient (cold acetone) was applied to HO and EVOO adulterated with HO. The subsequent in-solution tryptic digestion of protein extracts and MALDI-MS analysis, using α-cyano-4-chlorocinnamic acid as matrix, allowed the detection of stable hazelnut peptide markers (i.e., the m/z ions 1002.52, 1356.71, 1394.70, 1440.81, 1453.85, 1555.76, 1629.83, 1363.73, and 1528.67) attributable to the main hazelnut proteins Cor a 9, Cor a 11, and Cor a 1. Thus, the approach might allow the direct detection of specific hazelnut allergens in EVOO at low concentration without time-consuming pretreatments.

Oxidative changes of lipids monitored by MALDI MS

Oxidation processes of lipids are of paramount interest from many viewpoints. For instance, oxidation processes are highly important under in vivo conditions because molecules with regulatory functions are generated by oxidation of lipids or free fatty acids. Additionally, many inflammatory diseases are accompanied by lipid oxidation and, therefore, oxidation products are also useful disease (bio)markers. Thus, there is also considerable interest in methods of (oxidized) lipid analysis. Nowadays, soft ionization mass spectrometric (MS) methods are regularly used to study oxidative lipid modifications due to their high sensitivities and the extreme mass resolution. Although electrospray ionization (ESI) MS is so far most popular, applications of matrix-assisted laser desorption and ionization (MALDI) MS are increasing. This review aims to summarize the so far available data on MALDI analyses of oxidized lipids. In addition to model systems, special attention will be paid to the monitoring of oxidized lipids under in vivo conditions, particularly the oxidation of (human) lipoproteins. It is not the aim of this review to praise MALDI as the "best" method but to provide a critical survey of the advantages and drawbacks of this method.