“C. annuum metabolomic profiling depends on the growing area and hence is influenced by climatic conditions such as temperature and pluvial precipitation “
The chilli pepper is a valuable commercial commodity in Mexico, and is cultivated widely across several regions of the country. Indeed, Mexico is the sixth largest chilli exporter in the world1.
The economic importance of the chilli pepper in Mexico has created a need to be able to quickly and easily determine the quality of chilli peppers in terms of both flavour and nutritional value. Technological advances over recent years have made sophisticated analytical methodologies more accessible to chilli pepper producers, facilitating the rapid assessment of the properties of harvested chilli peppers.
In particular nuclear magnetic resonance spectroscopy (NMR), which can be readily automated and operated by non-experts2, enables simultaneous measurement of numerous endogenous metabolites. In addition, NMR spectroscopy produces highly reproducible spectra in a few minutes without damaging or contaminating the sample. Consequently, metabolomic analyses are now relatively easy to undertake.
Metabolomic analysis provides a unique chemical fingerprint that details all of the metabolites in the cells of living organisms3. In addition to characterising the composition of cells of a particular species, metabolomic analysis can provide valuable information on the response of a living entity to environmental conditions. It has been widely used in research across many disciplines, including toxicology and drug discovery.
A variety of types of natural produce, including cabbage, grapes, coffee and green tea, has been chemically profiled using NMR, and the differences between crops originating from different geographical regions explored 4,5. In addition, the information provided by NMR analysis can help determine the nutritional properties of a cultivated vegetable species and explore how these differ between different climates.
NMR metabolomic analysis has now been used to obtain the specific chemical fingerprint of the serrano chilli pepper. This is one of the most commonly cultivated varieties of green chilli pepper in Mexico. The serrano chilli pepper is known to contain a wide range of metabolites, the precise composition of which varies according to the genetics of the plant and the growing conditions 6,7.
A recent study used 1H NMR to obtain the metabolomic profiles of serrano chilli peppers cultivated in different regions of Mexico8. The two regions studied have very different climates; Oaxaca is characterised by a semi-dry, semi-warm climate whilst Veracruz has a warm climate with abundant rain in the summer and early autumn. The aqueous phase of serrano peppers harvested from the two regions were analysed using a Bruker 750 MHz NMR spectrometer equipped with a TXI probe.
The serrano chilli peppers were found to contain 40 different metabolites, the majority of which are of nutritional relevance. For example, 13 different amino acids, including seven essential amino acids, were identified8.
The levels of organic acids differed considerably between chilli peppers from Oaxaca and chilli peppers from Veracruz8. It was especially notable that chilli peppers from Oaxaca contained lactate but not succinate, whilst those from Veracruz contained succinate but not lactate. Since vitamin C in chilli peppers is produced from the organic acid oxalic acid, these differences in organic acids also impact on the nutritional value of the chilli peppers.
These findings highlight the importance of climate, which determines temperature patterns and water availability, in creating the precise chemical fingerprints of serrano chilli peppers. Since it is the metabolites determining these profiles that are responsible for the flavour and nutritional value of a chilli pepper, these properties too can be impacted by the climate of the area in which the chilli pepper is grown.
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- Wei F, et al. Journal of Agricultural and Food Chemistry 2016;64(33):6459‑6465.
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- González-Zamora A, et al. Molecules 2013;18(11):13471‑13486.
- Okunlola GO, et al. Sciences in Cold and Arid Regions 2016;8(3):205‑211.
- Becerra-Martínez E, et al. Food Research International 2017;102:163–170.
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