Relationship Between the Different Aspects Related to Coffee Quality and Their Volatile Compounds.

This paper provides, for the first time, an overview of different aspects related to the quality of coffee beans and their volatile fractions: species/cultivars, geographic origins, bean defects, and types of beverages, processing, roasting, and storage. In other words, it concerns the complex relation between the quality of coffee seeds and their volatile components. It is an overview of 48 articles and considering 6 different aspects related to the quality of coffee and its aromatic fraction. The greatest numbers of published papers concerned "species and cultivars" and "defective seeds," both with 11 articles cited, followed by "storage" with 10 articles. Many aspects still require greater clarification, including the effects of geographical origin, processing, and roasting. Other issues that are better understood include the effects of species type, defective seeds, and storage conditions. Another topic that has received very little attention is the question of the existence of many different coffee cultivars within each species, which we believe should be further investigated, given that this can significantly affect the quality of the final beverage. Meanwhile, with the growing technological development in the areas of science and agriculture, there are many other aspects to be studied (or revisited), and the field of the aromatic quality of coffee provides ample opportunity for scientific investigation.

Real-time monitoring of a coffee roasting process with near infrared spectroscopy using multivariate statistical analysis: A feasibility study.

This work proposes the use of near infrared (NIR) spectroscopy in diffuse reflectance mode and multivariate statistical process control (MSPC) based on principal component analysis (PCA) for real-time monitoring of the coffee roasting process. The main objective was the development of a MSPC methodology able to early detect disturbances to the roasting process resourcing to real-time acquisition of NIR spectra. A total of fifteen roasting batches were defined according to an experimental design to develop the MSPC models. This methodology was tested on a set of five batches where disturbances of different nature were imposed to simulate real faulty situations. Some of these batches were used to optimize the model while the remaining was used to test the methodology. A modelling strategy based on a time sliding window provided the best results in terms of distinguishing batches with and without disturbances, resourcing to typical MSPC charts: Hotelling's T2 and squared predicted error statistics. A PCA model encompassing a time window of four minutes with three principal components was able to efficiently detect all disturbances assayed. NIR spectroscopy combined with the MSPC approach proved to be an adequate auxiliary tool for coffee roasters to detect faults in a conventional roasting process in real-time.

Multiplexed analysis combining distinctly-sized CdTe-MPA quantum dots and chemometrics for multiple mutually interfering analyte determination.

Semiconductor quantum dots (QDs) have demonstrated a great potential as fluorescent probes for heavy metals monitoring. However, their great reactivity, whose tunability could be difficult to attain, could impair selectivity yielding analytical results with poor accuracy. In this work, the combination in the same analysis of multiple QDs, each with a particular ability to interact with the analyte, assured a multi-point detection that was not only exploited for a more precise analyte discrimination but also for the simultaneous discrimination of multiple mutually interfering species, in the same sample. Three different MPA-CdTe QDs (2.5, 3.0 and 3.8nm) with a good size distribution, confirmed by the FWHM values of 48.6, 55.4 and 80.8nm, respectively, were used. Principal component analysis (PCA) and partial least squares regression (PLS) were used for fluorescence data analysis. Mixtures of two MPA-CdTe QDs, emitting at different wavelength namely 549/566, 549/634 and 566/634nm were assayed. The 549/634nm emitting QDs mixture provided the best results for the discrimination of distinct ions on binary and ternary mixtures. The obtained RMSECV and R2CV values for the binary mixture were good, namely, from 0.01 to 0.08mgL-1 and from 0.74 to 0.89, respectively. Regarding the ternary mixture the RMSECV and R2CV values were good for Hg(II) (0.06 and 0.73mgL-1, respectively) and Pb(II) (0.08 and 0.87mg L-1, respectively) and acceptable for Cu(II) (0.02 and 0.51mgL-1, respectively). In conclusion, the obtained results showed that the developed approach is capable of resolve binary and ternary mixtures of Pb (II), Hg (II) and Cu (II), providing accurate information about lead (II) and mercury (II) concentration and signaling the occurrence of Cu (II).

Flow Injection Analysis of 5-(Hydroxymethyl)-2-furaldehyde in Honey by a Modified Winkler Method.

One of the quality indicators for honey is 5-(hydroxymethyl)-2-furaldehyde (HMF), which is formed during the heating or aging of honey. The International Honey Commission recommends three methods for the determination of HMF in honey: the Winkler method, the White method, and determination by HPLC. The Winkler method uses the carcinogenic substance p-toluidine, which is not in accordance with the principles of Green Chemistry. The present work describes the determination of HMF in honey by flow injection analysis (FIA) using a modified Winkler method, replacing p-toluidine with p-aminobenzoic acid. The linear range was 1.00 to 40.0 mg L(-1), the limit of detection (LOD) was 0.43 mg L(-1), and the limit of quantification (LOQ) was 1.32 mg L(-1). The method is an efficient and environmentally friendly technique for the analysis of HMF in honey.

Determination of glyphosate in water samples by multi-pumping flow system coupled to a liquid waveguide capillary cell.

A simple screening method was developed for the determination of glyphosate in water samples using a multi-pumping flow system. The proposed method is based on the reaction between glyphosate and p-dimethylaminocinnamaldehyde (p-DAC), in an acid medium where the reaction product can be measured spectrophotometrically at λ(max) = 495 nm. An experimental design methodology was used to optimize the measurement conditions. The proposed method was applied to the determination of glyphosate in water samples in a concentration range from 0.5 to 10 µg mL(-1). The limit of detection and quantification were 0.17 and 0.53 µg mL(-1), respectively. The results obtained (88.5 to 104.5%) in recovery studies for the determination of glyphosate in different water samples indicated good accuracy and no matrix effect for the developed method. Samples were also analyzed by a confirmatory HPLC method, and agreement within the two set of results was found.