Development of 2D and 3D front face fluorescence spectroscopy for monitoring ultrasound treatment in the removal of pesticides residues from fresh lettuces at the laboratory and pilot scales.

Pesticide residues in vegetables are potentially toxic components to humans and can cause serious health problems. To remove pesticide residues from fresh agricultural products and improve consumer food safety, various pesticide removal methods have been investigated over the past decades. In this study, the effectiveness of laboratory and pilot scale ultrasonic cleaning on the removal of boscalid and pyraclostrobin residues from lettuce was examined. 2D fluorescence spectroscopy, 3D fluorescence spectroscopy represented by excitation-emission matrix (EEM), and parallel factor analysis (PARAFAC) were used to characterize and discriminate the fluorescence signatures of these pesticides in the cleaning water to determine the effectiveness of the ultrasonic cleaning method as a function of the level of pesticide removal. The 2D fluorescence results showed that the rate of removal of boscalid by ultrasonics at the laboratory scale increased with the cleaning time. The ultrasonic treatment showed a higher cleaning efficiency compared to only soaking in distilled water for 10 min. The same trends were observed at the pilot scale. The EEM also showed differences in the concentration of pesticides removed by ultrasonication between the different parts of the lettuce, the concentration was higher in the upper part than the lower part. This study showed that ultrasonication is an effective technique for the removal of pesticide residues on lettuce, and it also showed the significant potential of fluorescence spectroscopy coupled with PARAFAC for the discrimination and characterization of pesticides.

A review combining emerging techniques with classical ones for the determination of biscuit quality: advantages and drawbacks.

The production of biscuit and biscuit-like products has faced many challenges due to changes in consumer behavior and eating habits. Today's consumer is looking for safe products not only with fresh-like and pleasant taste, but also with long shelf life and health benefits. Therefore, the potentiality of the use of healthier fat and the incorporation of natural antioxidant in the formulation of biscuit has interested, recently, the attention of researchers. The determination of the biscuit quality could be performed by several techniques (e.g., physical, chemical, sensory, calorimetry and chromatography). These classical analyses are unfortunately destructive, expensive, polluting and above all very heavy, to implement when many samples must be prepared to be analyzed. Therefore, there is a need to find fast analytical techniques for the determination of the quality of cereal products like biscuits. Emerging techniques such as near infrared (NIR), mid infrared (MIR) and front face fluorescence spectroscopy (FFFS), coupled with chemometric tools have many potential advantages and are introduced, recently, as promising techniques for the assessment of the biscuit quality.

Impact of storage period and lipid unsaturation on the kinetic of 5-hydroxymethylfurfural and furfural generation in pound cakes.

This work aimed at studying the influence of formulation and storage on the formation of Maillard compounds called 5-hydroxymethylfurfural (HMF) and furfural in pound cakes formulated with rapeseed oil (RO) and palm oil (PO). A progressive humidification of the crust and a dryness of the crumb were observed during storage. Lightness (L*) decreased for both PO and RO pound cakes in crumb as well as crust. The accumulation of HMF was found to be higher in the crust (2.21-38.5 mg kg-1) in comparison with the crumb (0.78 to 10.29 mg kg-1). Similar results were found for furfural where the concentration range was between 0.98 and 5.67 mg kg-1 in the crumb while between 2.1 and 38.39 mg kg-1 in the crust. Thus, the formation of HMF and furfural depended on formulation. The PLS-DA showed a positive correlation between the kinetic of HMF and furfural migration and the storage period.

Use of front face fluorescence spectroscopy coupled with multivariate data analysis for monitoring biscuits' quality during aging.

In this study, the potentiality of front face fluorescence spectroscopy (FFFS) for the evaluation of the quality of biscuits manufactured with butylated hydroxytoluene and pomegranate peel extract during aging was investigated. By using the principal component analysis, vitamin A and tryptophan spectra allowed a clear discrimination between biscuit samples according to the nature of antioxidants, while fluorescent Maillard reaction products spectra showed clear differentiation between samples according to the storage time. Clear differentiation between biscuits according to the used antioxidants and storage time was achieved by using common components and specific weights analysis. Using partial least-squares regression, excellent prediction of water activity (R 2 = 0.95), and L* values (R 2 = 0.92), and approximate prediction of hardness (R 2 = 0.78), b* values (R 2 = 0.74), and moisture content (R 2 = 0.74) were shown. However, the FFFS failed to predict a* values, primary and secondary oxidation products (R 2 < 0.6).

Assessing the quality of dry sausages using fluorescence spectroscopy, physico-chemical, and dynamic testing rheology: A preliminary study.

The viscoelastic and the structure properties of three brands of dry sausages (Auvergne, Beef-poultry, and Galbanetto) were studied using dynamic rheology and fluorescence spectroscopy. The storage and the loss modulus of sausage samples showed a viscoelastic character. The principal component analysis carried out on the normalized rheological and physico-chemical parameters allowed to differentiate the sausage samples into three groups according to their brands. This trend was confirmed by the factorial discriminant analysis where 74.44% of correct classification was obtained. The emission spectra acquired after excitation set at 290, 340, and 360 nm and excitation spectra scanned after emission set at 410 nm allowed clear differentiation between the three brand samples. The obtained results were confirmed following the application of partial least squares regression to the fluorescence and physico-chemical parameters since an excellent prediction of moisture content was obtained from the excitation spectra set at 340 nm (R2  = 0.99) and 360 nm (R2  = 0.99). The protein content of dry sausages was well predicted after excitation set at 290 and 340 nm with R2 of 0.96 and 0.97, respectively, while the fat level was well estimated after excitation set at 340 and 360 nm and emission set at 410 nm (R2  = 0.96, 0.96 and 0.94, respectively). The obtained results showed the potential use of fluorescence spectroscopy as a rapid technique for evaluating the quality of dry sausages.

Use of mid-infrared spectroscopy for quality monitoring and the prediction of physicochemical parameters of dry fermented chicken sausages enriched with sesame flour.

BACKGROUND: This study aimed to investigate the effects of the supplementation of sesame flour in fermented chicken sausages ('S1' containing 800 g kg-1 chicken fillet, 180 g kg-1 veal fat and 20 g kg-1 sesame flour and 'S2' containing 800 g kg-1 chicken fillet, 160 g kg-1 veal fat and 40 g kg-1 sesame flour) compared with control sausages (containing 800 g kg-1 chicken fillet and 200 g kg-1 veal fat) on the physico-chemical characteristics, texture, and structure during the fermentation stage. RESULTS: The physicochemical parameters of samples belonging to the control, S1, and S2 batches were significantly affected by the addition of sesame flour and the fermentation stage. For instance: (i) the lowest protein content was observed for control samples on day 1 (61.4 ± 6.52 g kg-1 ) whereas the highest level was noted for S2 samples on day 15 (327.5 ± 22.2 g kg-1 ), and (ii) an inverse trend was observed for the fat content because the lowest content was observed for samples in the S2 batch on day 1 (129.0 ± 5.30 g kg-1 ) whereas the highest fat content was noted for samples belonging to control batch on day 15 (332.0 ± 1.29 g kg-1 ). The application of statistical methods to mid-infrared spectroscopy allowed clear discrimination between control, S1, and S2 batches. The addition of sesame flour in the recipes induced some modification in the secondary structure because ß-turn levels ranged from 39.30 to 34.50, 36.76 to 34.70, and 38.93 to 34.70 for control, S1, and S2 batches, respectively, throughout the fermentation stage. Sodium dodecyl-sulfate polyacrylamide gel electrophoresis (SDS-PAGE) showed a similar protein profile pattern in the three batches on days 1 and 5, but on day 10 control and S2 batches showed the most intense degradation of myofibrillar proteins. CONCLUSION: The results demonstrated that mid-infrared spectroscopy coupled with chemometric tools could be used as a rapid screening tool to assess and monitor the quality of dry chicken sausages enriched with sesame flour throughout the fermentation stage. © 2022 Society of Chemical Industry.

Comparison of four classification statistical methods for characterising virgin olive oil quality during storage up to 18 months.

This study examines the ability of fluorescence spectroscopy for monitoring the quality of 70 Moroccan virgin olive oils belonging to three varieties and originating from three regions of Morocco. By applying principal component analysis and factorial discriminant analysis to the emission spectra acquired after excitation wavelengths set at 270, 290, and 430 nm, a clear differentiation between samples according to their storage time was observed. The obtained results were confirmed following the application of four multivariate classification methods: partial least squares regression, principal component regression, support vector machine, and multiple linear regression on the emission spectra. The best prediction model of storage time was obtained by applying partial least squares regression since a coefficient of determination (R2) and a root mean square error of prediction (RMSEP) of 0.98 and 24.85 days were observed, respectively. The prediction of the chemical parameters allowed to obtain excellent validation models with R2 ranging between 0.98 and 0.99 for free acidity, peroxide value, chlorophyll level, k232, and k270.

Application of new emerging techniques in combination with classical methods for the determination of the quality and authenticity of olive oil: a review.

The determination of the quality and authenticity of olive oil becomes more and more required by producers, consumers, and authorities to thwarter falsification. Several analytical techniques including chemical, sensory, chromatography, and so on, are used for the determination of the quality and authenticity of olive oil. Although these methods are considered as the reference ones, they are cumbersome, time-consuming and destructive. Therefore, rapid analytical techniques such as fluorescence, ultraviolet-visible, near infrared, and mid infrared spectroscopies, electronic sensing, among others, are more and more used for the determination of the quality and authenticity of olive oils. This review will identify current gaps related to different analytical techniques in olive oil authentication and discuss the drawbacks of existing analytical methods concerning olive oil authenticity from 2010 up to now.

Potentiality of front-face fluorescence and mid-infrared spectroscopies coupled with partial least square regression to predict lipid oxidation in pound cakes during storage.

The potentialities of front-face fluorescence (FFF) and mid-infrared (MIR) spectroscopies coupled with partial least square regression (PLSR) were compared to predict the lipid oxidation of pound cakes. The level of lipid oxidation in pound cakes determined using classical methods showed some changes. Similarly, the fluorescence emission (305-490 nm) and excitation (252-390 nm) spectra and MIR spectra scanned in the 4000-700 cm-1 region showed some changes in pound cakes as a function of both storage time and the type of oil used in the formulation. The application of PLSR to the MIR spectra, provided excellent predictive results for free fatty acid (R2 = 0.97) and peroxide values (R2 = 0.87). Similar results were obtained from both tryptophan and MIR spectra for the prediction of TOTOX (R2 > 0.86) demonstrating the efficiency of the MIR and FFF spectroscopies to qualify and quantify the level of lipid oxidation in pound cakes.

Use of front face fluorescence for monitoring lipid oxidation during ageing of cakes.

Front face fluorescence spectroscopy coupled with chemometric tools was used as a useful tool for the monitoring of sponge cakes freshness, produced at the pilot scale, during ageing (i.e. 1, 3, 6, 9, 16, and 20days). The fluorescence emission spectra were acquired in the 340-490nm and 390-680nm after excitation at 325 and 380nm, respectively, while excitation spectra (250-390nm) were scanned after emission at 410nm. The primary and secondary products of lipid oxidation were also determined on the same cakes. The principal component analysis (PCA) applied to the each spectral collection obtained after excitation at 325 and 380nm and emission at 410nm allowed a clear discrimination of cakes according to their ageing. A high correlation between the intensity of fluorescence at 521nm and the p-anisidine values was observed since squared correlation coefficient of 0.73 was obtained. The results showed that fluorescence spectroscopy could be used as a powerful tool for the evaluation of cake freshness throughout storage.

Monitoring changes in sponge cakes during aging by front face fluorescence spectroscopy and instrumental techniques.

In the present study, sponge cakes, produced at the pilot scale, were monitored during aging (i.e., 1, 3, 6, 9, 16, and 20 days) by three different analytical techniques. For the texture analyzer, the hardness and elasticity of crumb cakes were found to significantly increase and decrease, respectively, throughout aging. Color parameters (L*, a*, and b*) showed only slight change throughout aging, and a high correlation (R(2) = 0.88) was observed between the whiteness and the yellowness. Tryptophan fluorescence spectra (excitation, 290 nm; emission, 305-490 nm) recorded on cakes exhibited three maxima located at 382, 435, and 467 nm that were attributed to maximum emission of tryptophan (382 nm) and fluorescent Maillard reaction products (435 and 467 nm). The principal component analysis (PCA) applied to the tryptophan spectra allowed a clear discrimination of cakes aged for 1, 3, and 6 days from those aged for 9, 16, and 20 days. Finally, canonical correlation analysis (CCA) performed on the textural and tryptophan fluorescence spectral data sets showed that the two groups of variables were highly correlated because the squared canonical coefficients for canonical variates were 0.99, indicating that cake texture determined at the macroscopic level by texture analyzer is a reflection of its structure at the molecular level determined by fluorescence spectroscopy.

Temperature effect on Listeria monocytogenes growth in the event of contamination of cooked pork products.

The aim of this study was to describe the effect of temperature on the growth of Listeria monocytogenes in the event of postprocess contamination of packaged pork meats. This study was carried out in two steps. In the first step, the effect of temperature on L. monocytogenes growth rates was determined in duplicates at 13 temperatures between 2 and 43 degrees C by turbidimetric methods and adjusted by a quantitative secondary model. Then, seven sets of growth kinetics were collected by challenge testing in white pudding and roulade, both cooked pork products prepared according to an industrial process and stored at suboptimal temperatures ranging from 2 to 20 degrees C. In the second step, objectives were to (i) collect direct information on the temperature effect of L. monocytogenes on the two pork products, (ii) compare the two products regarding L. monocytogenes exposure, and (iii) compare results given by modeling (step i) with results obtained independently and then evaluate the model application domain. Each kinetic was built with at least 10 experimental data and two replicates. Comparison between L. monocytogenes behavior at 4 degrees C on white pudding and roulade indicated that both meat products were affected by food safety problems. Indeed, after contamination and storage for 10 days at 4 degrees C, the bacterial population increased by 2 log CFU/g in both products. Comparison between growth kinetic simulations and experimental data obtained separately gave satisfactory conclusions; the difference between observed and predicted bacterial population values was always less than 1 log CFU/g and a bias factor of 1.18 when growth rates were compared. These results applied to L. monocytogenes contamination of white pudding or roulade can now be used either in the management of optimal process and distribution networks or in risk assessment (exposure assessment).