Fluorescence lifetime imaging microscopy as a tool to characterize spice powder variations for quality and authenticity purposes: A ginger case study.

Spices are usually ground for applications and the resulting particle size of the powders is an important product attribute in view of the release of flavour. However, inhomogeneity of the original material may lead to variations in the physicochemical characteristics of the particles. This variation and its linkage to particle size may be examined by particular imaging techniques. This study aimed to explore the potential of Fluorescence Lifetime Imaging Microscopy (FLIM) to characterize spice powders according to particle size variations and correlation with their pigment contents to reveal the chemical information contained within the FLIM data. Ginger powder was used as a representative powder model. The FLIM profiles of the individual samples and populations revealed that FLIM coupled with the phasor approach has the capacity to characterize spice powder according to particle size. Meanwhile, Principal Component Analysis of pre-processed FLIM data revealed clustering of particle size groups. Further correlation analysis between the pigment compound contents and FLIM data of the ginger powders indicated that FLIM reflected chemical information of ginger powder and was able to visualize endogenous fluorophores. The current study revealed the potential of FLIM to characterize ginger powder particles. This approach may be extrapolated to other spice powder products. The new knowledge is a step further in paving the way for the application of innovative techniques, already prevalent in other domains, to food quality and authentication.

A sound approach: Exploring a rapid and non-destructive ultrasonic pulse echo system for vegetable oils characterization.

A rapid and non-destructive ultrasonic pulse echo system was developed for vegetable oils characterization. To understand the differences in the ultrasonic properties of the oils, physical traits, such as their viscosity and density, were related to the ultrasonic data. In turn, these physical traits were correlated with the fatty acid compositions of the oils. Eighty oil samples, including 30 extra virgin olive oil (EVOO), 15 refined olive oil, 15 pomace olive oil, 10 rapeseed oil, 5 sunflower oil and 5 peanut oil samples, were analysed for their sound properties, viscosities, densities and fatty acid compositions. It was observed that the ultrasonic velocity of EVOO decreased linearly with increase in temperature, the temperature coefficient of ultrasonic velocity in EVOO was -2.92 m·s-1·°C-1. The ultrasonic velocity of EVOO (1453 ±â€¯2 m/s) differed significantly from those of pomace olive oil and the oils of other botanical origin, but not from the velocity of refined olive oil. Ultrasonic velocity was positively correlated with the density and negatively correlated with the viscosity of the oils. The higher density and lower viscosity of the oils were in turn related to a higher unsaturation degree of the oils. Hence, oils with a higher proportion of unsaturated fat present higher densities and lower viscosities, which resulted in higher ultrasonic velocity values. Ultrasonic measurements allow rapid, non-destructive analysis, and this first application for characterization of these oils is promising.

Discrimination of processing grades of olive oil and other vegetable oils by monochloropropanediol esters and glycidyl esters.

In this study, the processing derived contaminants 2- and 3-monochloropropanediol (2- and 3-MCPD) esters and glycidyl esters (GEs) were analysed in 84 oil samples by GC-MS/MS for the discrimination of processing grades of olive oils as a potential authentication tool. Concentrations of 2- and 3-MCPD esters and GEs varied in the ranges 0-6 mg/kg, 0-1.5 mg/kg, and 0-1 mg/kg oil, respectively. The concentrations of the three compounds in lower grade olive oils were significantly higher (P < .001) than that in EVOO. A similar difference was observed for other refined and cold-pressed vegetable oils. The limit of fraud detection of lower grade oils in EVOO was 2% when using 3-MCPD esters, 5% for 2-MCPD esters, and 13-14% for GEs based on calculations of virtual mixtures of the current sample set. Especially the MCPD esters appear very specific and promising for the detection of lower processing grade oils in EVOO.

Discrimination of pulp oil and kernel oil from pequi (Caryocar brasiliense) by fatty acid methyl esters fingerprinting, using GC-FID and multivariate analysis.

Pequi is an oleaginous fruit whose edible oil is composed mainly by saturated and monounsaturated fatty acids. The biological and nutritional properties of pequi oil are dependent on its composition, which can change according to the oil source (pulp or kernel). There is little data in the scientific literature concerning the differences between the compositions of pequi kernel and pulp oils. Therefore, in this study, different pequi genotypes were evaluated to determine the fatty acid composition of pulp and kernel oils. PCA and PLS-DA were applied to develop a model to distinguish these oils. For all evaluated genotypes, the major fatty acids of both pulp and kernel oils were oleic and palmitic acids. Despite the apparent similarity between the analyzed samples, it was possible to discriminate pulp and kernel oils by means of their fatty acid composition using chemometrics, as well as the unique pequi genotype without endocarp spines (CPAC-PQ-SE-06).

Authentication of geographical origin and crop system of grape juices by phenolic compounds and antioxidant activity using chemometrics.

The main goal of this work was to propose an authentication model based on the phenolic composition and antioxidant and metal chelating capacities of purple grape juices produced in Brazil and Europe in order to assess their typicality. For this purpose, organic, conventional, and biodynamic grape juices produced in Brazil (n = 65) and in Europe (n = 31) were analyzed and different multivariate class-modeling and classification statistical techniques were employed to differentiate juices based on the geographical origin and crop system. Overall, Brazilian juices, regardless of the crop system adopted, presented higher contents of total phenolic compounds and flavonoids, total monomeric anthocyanins, proanthocyanidins, flavonols, flavanols, cyanidin-3-glucoside, delphinidin-3-glucoside, and malvidin-3,5-glucoside. No differences were observed for trans-resveratrol, malvidin-3-glucoside, and pelargonidin-3-glucoside between countries and among crop systems. A total of 91% of Brazilian and 97% of European juices were adroitly classified using partial least squares discriminant analysis when the producing region was considered (92% efficiency), in which the free-radical scavenging activity toward 2,2-diphenyl-1-picrylhydrazyl, content of total phenolic compounds, gallic acid, and malvidin-3-glucoside were the variables responsible for the classification. Intraregional models based on soft independent modeling of class analogy were able to differentiate organic from conventional Brazilian juices as well as conventional and organic/biodynamic European juices.

Analytical strategy coupled with response surface methodology to maximize the extraction of antioxidants from ternary mixtures of green, yellow, and red teas (Camellia sinensis var. sinensis).

This work aimed at using a simplex-centroid design to model the effects of green, yellow, and red tea mixtures (Camellia sinensis var. sinensis) on metal chelation activity, phenolic composition, antioxidant activity, and instrumental taste profile. The regression models that described the extraction of flavan-3-ols, o-diphenols, total phenolic compounds (TPC), free radical scavenging activity toward 2,2-diphenyl-1-picrylhydrazyl radical (DPPH), cupric ion reducing antioxidant activity (CUPRAC), and ferric reducing antioxidant power (FRAP) were significant, and data were fit satisfactorily (R(2) > 80%). A mixture of green and red teas had a synergism in CUPRAC and TPC, whereas a mixture of yellow and red teas had a positive effect on CUPRAC and DPPH. An optimization was performed to maximize the antioxidant activity and flavan-3-ol content and to render a tea with mild bitterness, and results showed that a mixture of 14.81% green, 56.86% yellow, and 28.33% red teas would be the most suitable combination of factors.

Authentication of geographical origin of palm oil by chromatographic fingerprinting of triacylglycerols and partial least square-discriminant analysis.

Main goals of the present work were to develop authentication models based on liquid and gas chromatographic fingerprinting of triacylglycerols (TAGs) from palm oil of different geographical origins in order to compare them. For this purpose, a set of palm oil samples were collected from different continents: South eastern Asia, Africa and South America. For the analysis of the information in these fingerprint profiles, a pattern recognition technique such as partial least square discriminant analysis (PLS-DA) was applied to discriminate the geographical origin of these oils, at continent level. The liquid chromatography, coupled to a charged aerosol detector, (HPLC-CAD) TAGs separation was optimized in terms of mobile phase composition and by means of a solid silica core column. The gas chromatographic method with a mass spectrometer was applied under high temperature (HTGC-MS) in order to analyze the intact TAGs. Satisfactory chromatographic resolution within a short total analysis time was achieved with both chromatographic approaches and without any prior sample treatment. The rates of successful in prediction of the geographical origin of the 85 samples varied between 70% and 100%.

A review of analytical methods for the identification and characterization of nano delivery systems in food.

Detection and characterization of nano delivery systems is an essential part of understanding the benefits as well as the potential toxicity of these systems in food. This review gives a detailed description of food nano delivery systems based on lipids, proteins, and/or polysaccharides and investigates the current analytical techniques that can be used for the identification and characterization of these delivery systems in food products. The analytical approaches have been subdivided into three groups; separation techniques, imaging techniques, and characterization techniques. The principles of the techniques together with their advantages and drawbacks, and reported applications concerning nano delivery systems, or otherwise related compounds are discussed. The review shows that for a sufficient characterization, the nano delivery systems need to be separated from the food matrix, for which high-performance liquid chromatography or field flow fractionation are the most promising techniques. Subsequently, online photon correlation spectroscopy and mass spectrometry seem to be a convenient combination of techniques to characterize a wide variety of nano delivery systems.

Partition and release of 21 aroma compounds during storage of a pectin gel system.

The increasing popularity of low-fat products increases the need for a better understanding of how flavor release is affected by partial substitution of fat with hydrocolloids. Partitioning and release of aroma compounds from four pectin gels with different compositions were studied with static headspace and with a model mouth. Air/product partition coefficients determine the potential extent of aroma release, and mass transfer determines the rate at which aroma compounds are released to the vapor phase. This study showed that the gel network had large effects on the partition of aroma compounds between the gel and vapor phase. The specific properties of the aroma compounds were also of importance for the air/gel partition. Storage of the four gels showed that one of the weaker gels was influencing the concentration of aroma compounds in the headspace, probably caused by formation of a denser network over time.

The influence of gel strength on aroma release from pectin gels in a model mouth and in vivo, monitored with proton-transfer-reaction mass spectrometry.

The course of events from taking a food into the mouth to the perception of the food's flavor involves many steps, from dilution with saliva, mastication, and transportation of the compounds to the olfactory epithelium to transformation into signals that go to the brain. In addition, there are also the effects of the food's structure and properties. In this study, a proton-transfer-reaction mass spectrometer (PTR-MS) was used to investigate how four pectin-containing systems with different structures and strengths affected the release of aroma compounds in a model mouth and in the nose of an assessor. Both the model mouth and the in-nose measurements showed that the strength and structure of pectin-containing systems are important with regard to the quantity of aroma compounds that are released. Mastication and saliva were also shown to have a large influence on how much of the aroma compound is released from the mouth to the nose.

Influence of lipid fraction, emulsifier fraction, and mean particle diameter of oil-in-water emulsions on the release of 20 aroma compounds.

The influence of compositional and structural properties of oil-in-water emulsions on aroma release was examined under mouth conditions. The lipid (0.40 and 0.65) and emulsifier fractions (0.007, 0.010, and 0.014) were varied, as well as the mean particle diameter of the dispersed phase (0.60, 0.73, 0.85, and 1.10 microm). Aroma compounds were isolated in a model mouth system and quantified by gas chromatography-mass spectrometry. Studies were carried out to separate effects on the thermodynamic and the kinetic components of aroma release using equilibrium headspace analysis to distinguish the thermodynamic component. The lipid phase of the emulsions was composed of sunflower oil and the emulsifier phase was Tween 20. The release of 20 aroma compounds was evaluated; the compounds included alcohols (1-propanol, 1-butanol, 3-methyl-1-butanol, 2-pentanol, 1-hexanol, and 2-nonanol), ketones (diacetyl, 2-butanone, 2-heptanone, 2-octanone, and 2-decanone), esters (ethyl acetate, propyl acetate, butyl acetate, and ethyl butyrate), aldehydes (hexanal, heptanal, and octanal), a terpene (alpha-pinene), and a sulfur compound (dimethyl sulfide). Decrease in lipid fraction and emulsifier fraction, as well as increase in particle diameter, increased aroma release under mouth conditions. Differences between groups of compounds and between compounds of homologous series with varying chain lengths were found. Changes in particle diameter had a considerable effect on the thermodynamic component of aroma release, whereas hardly any influence of the lipid fraction and emulsifier fraction was observed. Lipid fraction, emulsifier fraction, and particle diameter affected the kinetic component of aroma release, which could partially be attributed to changes in viscosity.