Changes in bioactive compounds and antioxidant activity during convective drying of murta (Ugni molinae T.) berries

Murta (Ugni molinae T.) berries were air‐dried at five temperatures (40, 50, 60, 70 and 80 °C), and the changes in β‐carotene, phenolic acids, total phenolic and flavonoid contents and antioxidant capacities (DPPH and ORAC) were investigated. The berries showed a high content of β‐carotene, which decreased during drying temperature between 40 °C and 80 °C. Free and bound phenolic acids were also determined, showing gallic acid to be the prevalent phenolic acid. Total phenolic and flavonoid contents in the dried berries showed a higher decrease at lower temperature due to longer drying time. The radical‐scavenging activity also showed higher antioxidant activity at higher drying temperatures (70–80 °C) than at lower drying temperatures (40–50 °C). Total phenolic content (TPC) and flavonoids showed good correlation with antioxidant capacity. Murta berries proved to be an excellent source of antioxidants and bioactive compounds and are therefore a potential ingredient for new functional food products.     

Do as I say or as I do? Food handler's knowledge on good handling practices and evaluation of hygienic–sanitary conditions in hospital foodservices

The aim of the study was to evaluate the overall hygienic–sanitary conditions of university hospitals foodservices and assess food safety knowledge and self‐reported practices of food handlers. A self‐administered questionnaire based on sanitary standards for foodservices was given to 123 food handlers from three public hospitals. Microbiological analysis of food handling surfaces and food hygiene inspections were also performed. Food handlers' self‐reported knowledge and practices reached satisfactory levels (77.2% and 78.1%, respectively), and showed a significant positive intercorrelation (p < .05). Food hygiene inspections in the hospitals foodservices presented a 60.9% average of adequacy and microbiological analysis results showed that 66.7% of the evaluated surfaces presented significant contamination by mesophilic bacteria. The presence of coliforms at 45°C above the safety limit was identified in 47.9% of the surfaces. The results showed a need for motivating hospital food handlers to practice the safe handling knowledge that they have demonstrated in theory.     

Modelling the Water Sorption Isotherms of Quinoa Seeds (<Emphasis Type="Italic">Chenopodium quinoa</Emphasis> Willd.) and Determination of Sorption Heats

Adsorption and desorption isotherms of quinoa seeds (Chenopodium quinoa Willd.) were measured using the static gravimetric method at three temperatures (20, 40 and 60 °C). Water activity ranged from 0.118 to 0.937. The moisture sorption behaviour of quinoa was temperature dependent, as indicated by a decrease in equilibrium moisture content, at all levels of a _w, with increasing temperature. Eight mathematical equations available in the literature were used to model the experimental data, namely, GAB, BET, Caurie, Henderson, Oswin, Halsey, Smith and Iglesias–Chirife. All the equations showed generally a good fit; however, the Iglesias–Chirife and Oswin equations were considered the best to predict the experimental data for both isotherms. Effect of temperature on model parameters was analysed and studied through an Arrhenius-type equation. The net isosteric heats of desorption and adsorption were determined by applying the Clausius–Clapeyron equation resulting in 69.24 kJ mol⁻¹ for desorption and 61.26 kJ mol⁻¹ for adsorption. The experimental heat data were satisfactorily modelled by Tsami’s equation.     

Description of the kinetic enzymatic browning in banana (Musa cavendish) slices using non-uniform color information from digital images

A novel methodology “fractal browning indicator” (FBI) is presented, that describes the enzymatic browning kinetic based on the use of irregular color patterns from banana slice images. It uses the fractal Fourier texture image value in a selected area, to calculate a fractal dimension (FD), which represents the complexity of color distribution. During the procedure, colors from digital images were first transformed to L^*a^*b^* space color using a transformation function (quadratic model), in order to derivate three color channels, lightness (L^*), redness (a^*), and yellowness (b^*). In the results, lightness and yellowness parameters decreased during the browning kinetic, when their respective FD values increased, indicating major color distribution complexity in a selected area analyzed during the kinetic. The redness color (a^*) did not show any statistical variation. The empirical power law model was suitable to correlate enzymatic browning kinetic data both for FBI and for the traditional method (when an L^* mean was used). However, enzymatic browning rates using the FBI method, were between 8.5 and 35 times higher than rates calculated with the traditional method.     

Hot-air drying characteristics of Aloe vera (Aloe barbadensis Miller) and influence of temperature on kinetic parameters

The aim of this research was to study and model the kinetics of the hot-air drying of Aloe vera (Aloe barbadensis Miller) and to evaluate the influence of temperature on the kinetic parameters for the proposed models. A convective dryer was used at 50, 60, 70, 80 and 90 °C with an air flow of 2.0±0.2 m/s. The sorption isotherm of the fresh product was mathematically described by the Guggenheim, Anderson and de Boer (GAB) model, giving as a result monolayer moisture of 0.20 g water/g d.b. The mathematical models evaluated in the kinetic research included five empirical equations (Newton, Henderson-Pabis, Page, modified Page and Fick's diffusional model). The fit quality of the proposed models was evaluated by using the linear regression coefficient (r²), sum square error (SSE), root mean square error (RMSE) and Chi-square statistic (χ²). The diffusivity coefficient increased with the temperature from 5.30 to 17.73×10⁻¹⁰ m²/s, for a range of temperatures between 50 and 90 °C, with an estimated activation energy of 30.37 kJ/mol. When comparing the experimental moisture values with those estimated by the proposed models, the modified Page model provided the best to fit of the data, showing that this equation correctly simulates the Aloe vera drying process and represents an excellent tool for estimating its drying time.     

Use of electronic nose and trained sensory panel in the evaluation of tomato quality

In this paper the performances of an electronic nose based on metalloporphyrin‐coated quartz microbalance sensors and of an experienced panel of seven human assessors in the evaluation of gases derived from degradation reactions in tomatoes are presented and discussed. The performances are measured in terms of the capability of both systems to distinguish between samples of different quality coming from conventional and organic production systems. The study deals with the application of pattern recognition techniques based on either multivariate statistical methods (PCA, GPA) or artificial neural networks using a self‐organising map (SOM). The response pattern of the sensor array and the sensory data are analysed and compared using these methods. Similarities in the classification of the data by electronic nose and human sensory profiling are found. © 2000 Society of Chemical Industry     

Polymerase chain reaction coupled with peptide nucleic acid high-performance liquid chromatography for the sensitive detection of traces of potentially allergenic hazelnut in foodstuffs

A new DNA extraction method suitable for a wide variety of complex food matrices has been devised and applied in combination with a new polymerase chain reaction (PCR) method for the sensitive detection of a specific DNA sequence univocally identifying the presence of potentially allergenic hazelnut (Corylus avellana). A 156 base pair amplicon corresponding to an internal region of the complementary DNA of the major hazelnut allergen (Cor a 1) was designed, and was found to be highly specific; the method was tested on both pure and complex food matrices and was found to be able to confirm the presence of hazelnut down to 5 pg of its DNA. The sequence of the amplicon was further confirmed by high-performance liquid chromatography (HPLC) analysis with a specific peptide nucleic acid (PNA) probe. A 15-mer PNA probe was expressly designed and synthesized to hybridize an internal sequence of the previously described amplicon. Given its reported sequence specificity and high hybridization efficiency, the PNA probe was used to develop an anion-exchange HPLC method allowing for a fast and reliable confirmation of the identity of the amplified products. The PCR–HPLC method was successfully tested on commercial samples, allowing for the detection of the presence of potentially hidden allergens even in products where the presence of hazelnut as an ingredient or possible contaminant was not reported.     

Determination of flonicamid and its metabolites in bell pepper using ultra-high-performance liquid chromatography coupled to high-resolution mass spectrometry (Orbitrap)

The development and validation of a method to determine flonicamid and its metabolites as TFNA (4-trifluoromethylnicotinic acid), TFNG (N-(4-trifluoromethylnicotinoyl) glycine) and TFNA-AM (4-trifluoromethylnicotinamide) in bell pepper samples by ultra-high-performance liquid chromatography coupled to Orbitrap mass spectrometry (UHPLC-Orbitrap-MS) was performed. A fast and simple extraction procedure with acidified acetonitrile and salts (magnesium sulfate and sodium chloride) was used. The methodology was validated, checking for specificity, recovery, precision, limits of detection (LODs) and limits of quantification (LOQs). The recoveries ranged from 84% to 98%, and precisions were lower than 17%. Finally, LODs ranged from 1 µg kg^–1 (flonicamid) to 6 µg kg^–1 (TFNA-AM), while LOQs ranged from 10 µg kg^–1 (flonicamid) to 30 µg kg^–1 (TFNA-AM). Bell pepper samples were analysed and concentrations up to 98 µg kg^–1 (flonicamid) were detected, although the sum of flonicamid and metabolites did not exceed the maximum residue limit (MRL) set by the European Union.     

Efficient very‐high‐gravity fermentation of sugarcane molasses by industrial yeast strains

In this study industrial strains were inoculated, in successive cycles, at high cell density into a sugarcane‐based juice containing normal (22%, w/v) and very high sucrose (30%, w/v) levels and supplemented with peptone as a nitrogen source. At 30 °C, in shaken cultures, in the normal gravity situation, efficient sucrose utilization occurred in both the supplemented and unsupplemented medium. At higher sugar concentrations, supplementation with peptone induced a more efficient fermentation compared with the unsupplemented medium, with higher biomass accumulation and maintenance of cell viability, and ethanol levels as high as 16% (v/v). Trehalose was also high during the cycles, probably as a necessary response of the yeast to the high stress fermentation conditions. This suggests that it is possible to increase ethanol production by using very‐high‐fermentation technology and that nutritional supplementation would have a positive effect on the fermentation, allowing for efficient sugar consumption and cell viability maintenance. Copyright © 2016 The Institute of Brewing & Distilling