Advanced Analytical Methods for the Determination of Plant-Derived Small Molecules in Food Products

Plant-derived small molecules are natural compounds having a molecular weight < 900 Da, which play a role in the adaptation of plants to the environment and in overcoming stress conditions. Examples of these molecules include phenolic compounds, such as flavonoids, acids, stilbenes, tannins, and curcuminoids. Other important phytochemicals that have key roles in plant-environment interactions are carotenoids, glucosinolates, saponins, small carbohydrates, and volatile compounds such as terpenoids. All these plant-derived small molecules are also known to affect food quality in terms of organoleptic and bioactive properties, thus influencing both consumer appeal and health benefits. As such, food flavour is defined by volatile compounds, tannins, and saponins, food color by anthocyanins and carotenoids, and food bioactive properties by phenolic compounds, carotenoids, small carbohydrates, and glucosinolates. Natural toxins in food plants are also important for the consumer health, as when ingested they can be potentially harmful. These toxins are produced by plants to defend themselves against bacteria, fungi, insects, and predators. Lectins, cyanogenic and cardiac glycosides, and alkaloids like colchicine and muscarine are some examples of food plant toxins. Additionally, phytohormones – known as regulators of plant growth and environmental interactions – have critical roles in the modulation of synthesis of the small molecules described above, which can also impact food quality. Many of these small molecules are present in trace amounts in plant foods and some of them are still to be discovered. Thus, the accurate identification and quantification of plant-derived small molecules in food using advances techniques in analytical chemistry, such as gas (GC) and liquid (LC) chromatography coupled to mass spectrometry (MS), nuclear magnetic resonance (NMR), Fourier transform infrared (FTIR), and Raman spectroscopy, are active areas of research.
Due to the diversity of physicochemical properties and matrices associated with plant-derived small molecules, there is a wide range of analytical methods in the literature presently employed. However, there is a lack of harmonized extraction protocols that compromise the comparison of results among different studies within similar matrices. Additionally, some methodologies are tedious and time-consuming, hindering the possibility of high-throughput extractions or compromising the accuracy of the results in an attempt to scale-up daily throughput. Finally, the current availability of cutting-edge technology for use in analysis of plant-derived small molecules in food enables both targeted (i.e., known compounds) and non-targeted (i.e., unknown compounds) identifications. Advances in these areas will enable greater information to be obtained on new compounds with novel properties and future applications that can be used in food product formulation, defining a new era in food metabolomics.

The main goal of this Research Topic is to gather different and diverse analytical methodologies currently employed in the determination of plant-derived small molecules in food to assist scientists in the selection of proper analytical techniques and extractions protocols, harmonizing methodologies, and exploring the existing literature on plant food metabolomics. This Research Topic will cover methodologies dedicated both to targeted and untargeted analysis of plant-derived small molecules in food, comprising quantitative and qualitative analyses that will include sample preparation, analytical instrumentation, and data processing.

The aim of the current Research Topic is encompassing optimized, novel, and promising analytical methodologies in the field of analytical chemistry to identify and quantify novel and known plant-derived small molecules in food. This will include both processed and non-processed products. We welcome original research articles, reviews, and mini reviews on areas that may include, but are not limited to:

• Novel and optimized extraction protocols
• Chromatography and Mass spectrometry (MS)
• Nuclear magnetic resonance (NMR)
• Fourier transform infrared (FTIR)
• Targeted and untargeted metabolomics
• Bioactives compounds
• Aroma and flavour compounds
• Food quality and functionality