Analytical techniques combined with chemometrics for authentication and determination of contaminants in condiments : A review

Spices and herbs play an important role as flavorings, colorants, and also as bioactive compounds used in medicine and cosmetics. The presence of common contaminants, e.g., mycotoxins, pesticide residues, heavy metals, and the adulterants, e.g., azo dyes, filth and extraneous matter have been permanently monitored in condiments in order to control their quality, compliance to market, and safety to human health. The present paper shows a comprehensive overview of the analytical methods, based on the modern instrumental techniques and the most perspective statistical tools, based on univariate and multivariate (chemometrics) statistics, used for qualitative and quantitative determination of contaminant levels and for the authentication issues of different spices and herbs, discriminated by their geographic or biological origin. The review comprises more than sixty studies covering the last decade, describing the benefits of different analytical methods including multidimensional (non-targeted and targeted) approaches combined with multivariate chemometric techniques for the assessment of contaminants in spices and herbs in relation to research of their safety and quality issues. The methods based on multivariate data description and regression techniques are among the most promising techniques for the authentication of spices/herbs and determination of their contamination or adulteration risks with potential hazards.</p

No more nutmegging with nutmeg : Analytical fingerprints for distinction of quality from low-grade nutmeg products

Quality nutmeg is characterized by a delicate aroma. Next to quality nutmeg, other – lower - grades exist on the market, such as extracted material (spent) or ground shell or dried fruit pulp. Strong fluctuations in the price of nutmeg lead to rapid changes in market dynamics and marketing opportunities, and unfortunately results in illegal commingle of ground quality nutmeg with low-grade material. In this study, we examined fingerprints of volatile and non-volatile compounds of high quality and low-grade nutmeg material by Proton Transfer Reaction Mass Spectrometry and Flow Infusion ElectroSpray Ionization Mass Spectrometry, respectively. They were compared with data from classical measurements such as total ash, acid insoluble ash, moisture and volatile oil contents. Differences in composition were examined by univariate and multivariate statistical methods. Furthermore, one-class classification models for quality nutmeg were estimated using different algorithms and their performances were examined with quality nutmeg and low-grade material, as well as mixtures thereof. Distinct differences between quality nutmeg and low-grade nutmeg samples were observed for both their volatile and non-volatile fingerprints. Intensities of volatiles and non-volatiles are highly correlated, but this phenomenon diminishes gradually and even reverses with rising molecular mass of the non-volatiles. Results showed that both techniques allowed a nearly 100% correct prediction of quality nutmeg and low-grade nutmeg samples. Therefore, both approaches are promising and with further database extension, they may become a valuable addition to the analytical authentication toolbox in addition to the classical methods and help to detect future ‘nutmeggers’.</p

A cool comparison of black and white pepper grades

Black pepper (BP) is globally the most widely used spice and is appreciated for its aroma and taste qualities. Its aroma is influenced by various factors. In the current study, we examined a reference set of 90 quality BP and 40 quality white pepper (WP) samples from the EU spice industry for their volatile organic compounds (VOC) by Proton Transfer Reaction - Mass Spectrometry, as well as 10 low-grade pepper (LG) samples (light berries, rejects, spent). Furthermore, 50 retail BP and 30 WP samples were compared with the reference set. The predominant VOC measured were terpenes. BP presented the most abundant VOC profiles, followed by the WP group, and - at some distance - by the LG pepper material. Reference BP exhibited significantly higher intensities for 41% of the masses compared to WP, and the LG group lower intensities than both BP and WP for 27% of the masses. When using mass 137, the monoterpenes marker, retail samples presented significantly lower VOC intensities than their reference counterparts in case of 42% of the retail BP and 70% of the WP samples. Those samples may have suffered from poor storage conditions during production or potential adulteration or substitution with LG material.</p