Molecular thermodynamic models for the vapor-liquid equilibrium of nonpolar fluids

We propose simple expressions giving the main vapor-liquid properties for 42 nonpolar fluids. These expressions are molecular models based on a perturbative procedure, where the Lennard-Jones (LJ) system is taken as reference, the perturbed expressions being simple polynomial functions of the temperature for a given substance. The molecular parameters used, which are the only input needed in the molecular models, are the two LJ parameters, related to molecular size and the molecular interaction intensity, and the acentric factor, related to the molecular shape. The proposed molecular models are extrapolatable outside the temperature range used in the fit and seem to be easily applicable to other nonpolar fluids.     

Changes in vitamin C content and antioxidant capacity of raw and germinated cowpea (Vigna sinensis var. carilla) seeds induced by high pressure treatment

The effect of high pressure treatment on the vitamin C content and antioxidant capacity of raw and germinated cowpea seeds (Vigna sinensis var. carilla) at 300, 400 and 500 MPa for 15 min at room temperature has been investigated. A considerable amount of vitamin C was detected in germinated cowpeas, but the vitamin was not detected in raw seeds. An increase on the antioxidant capacity (TEAC) in cowpea sprouts was also observed (58–67%). High pressure treatment (HP) slightly modified vitamin C content and TEAC and, after pressurization at 500 MPa, the decrease was more pronounced, although the germinated seeds submitted to this HP treatment still provided a high amount of vitamin C (15–17 mg/100 g d.m.) and the antioxidant capacity was 26–59% higher than that of the raw cowpeas. The HP process can provide minimally processed fresh-like sprouts of high quality.     

Improvement in food intake and nutritive utilization of protein from Lupinus albus var. multolupa protein isolates supplemented with ascorbic acid

The protein quality of protein isolates from lupin (LPI) (Lupinus albus var. multolupa), prepared by isoelectric precipitation, was assessed by chemical analysis of protein and amino acids and biological analysis of digestive and metabolic utilization of protein by growing rats. The animals were fed isonitrogenous and isocaloric diets adjusted to meet their nutrient requirements, in which lupin protein isolate was the only protein source, complemented with 0.5% methionine. Different LPIs were prepared with addition, or not, of ascorbic acid as antioxidant. Protein isolates had a protein content of 87.8–98.1%. Manganese content of protein isolates was reduced by 72.8–89.5% compared to the raw seed flour. Results from in vivo experiments showed that addition of 0.5% ascorbic acid to LPI incorporated into diets led to a 82.8% increase in daily food intake, when compared to the non-supplemented LPI, reaching similar values to those obtained with a casein–methionine control diet. Digestive and metabolic utilization of protein from LPI, assessed by nitrogen absorption or apparent digestibility coefficient, and by nitrogen balance or percentage of retained to absorbed nitrogen, respectively, was high, when the dietary intake of animals fed the LPI diets was adequate after addition of 0.5% ascorbic acid, although slightly inferior to the values obtained with a casein–methionine control diet. The high nutritive utilization of protein was reflected in excellent growth and nutritional indices assayed. In conclusion, ascorbic acid supplementation led to an improvement in the palatability of the LPI diets and, therefore, in daily food intake, which was reflected in a higher nutritive utilization of protein and improvement in weight gain and the food transformation index.     

Shelf life of ostrich (Struthio camelus) liver stored under different packaging conditions

Ostrich (Struthio camelus) liver is an important edible meat by-product. However, it has a low commercial value, and it is underutilized. The present study was conducted to establish the shelf life of ostrich liver, stored at 2 +/- 1 degrees C for 18 days, under different packing conditions. Fresh livers were sliced and packed under air exposure, vacuum, and modified atmosphere (MA: 80% CO2 plus 20% N2). Shelf-life evaluation was based on color, lipid and hemopigment oxidation, microbial counts, and sensory assessment of odor and color. Samples stored under air exposure showed the highest lipid and hemopigment oxidation rate, which was detected by higher thiobarbituric acid reactive substances values and metmyoglobin percentage and lower heme iron content than livers stored under vacuum or MA. On the basis of aerobic bacteria counts, the shelf life of ostrich liver stored under aerobic conditions would be 7 days, whereas under vacuum or MA, it would be 14 days. In livers stored under anaerobic conditions (vacuum or MA packed), lactic acid bacteria represented a significant proportion of the spoilage microbiota. Minimal changes in color perception were also obtained in vacuum-packed samples at the end of the storage period. In air-packed samples, high levels of off-odors were already perceived during the first 6 days of storage, whereas in livers stored under anaerobic conditions (vacuum and MA), these levels of off-odor were not yet perceived at that time.     

Effect of amines in the release of bisphenol A from polycarbonate baby bottles

The key block for the production of polycarbonate (PC) is bisphenol A (BPA). Recent studies have proven that this monomer is able to migrate from PC baby bottles into food simulants and, although this is a polemical subject, numerous investigations indicate that BPA may have an effect on the human health. For these reasons, BPA safety regarding human exposure has recently become an alarming issue.Amines are a class of chemicals which are present in foodstuffs, such as milk. For this reason PC baby bottles, while being used, are continuously in contact with several amines, some of which are able to cause PC aminolysis, resulting in the release of BPA.In this work, 16 substances (14 with amine groups and 2 with amide groups) were tested in order to verify if they were able to increase BPA release by increasing PC depolymerization. High-performance liquid chromatography (HPLC) with fluorescence detection (FLD) and gas chromatography coupled to mass spectrometry (GC–MS) were used to quantify and identify the BPA, respectively. Although most of the substances tested did not increase the release of BPA from PC, some of them had a significant effect and high levels of this monomer were measured in the solutions. Of all of the amines tested that originating the worst case of BPA release was 1,4-diaminobutane. Also known as putrescine, 1,4-diaminobutane is a biogenic amine that results from protein degradation and it may be present in milk. In this case, BPA concentration in the solution was more than 5000 times the level found in the control sample.     

The Flavonoid Eriodictyol as Substrate of Peach Polyphenol Oxidase

ABSTRACT: Spectral changes produced in the oxidation of eriodictyol by peach polyphenol oxidase were followed over time. A product with λ_max= 390 nm was seen to appear before another with λ_max= 475. The product absorbing at 390 nm must correspond to the o -quinone derived from eriodictyol. The compound absorbing at 475 nm must be derived from this eriodictyol-o-quinone. Progress curves at this wavelength revealed a lag, the length of which varied with enzyme and substrate concentrations. This lag must have been caused by chemical reactions taking place after the enzymatic reaction. When eriodictyol oxidation was studied in the presence of 3-methyl-2-benzothiazolinone hydrazone hydrochloride (MBTH), a potent nucleophilic reagent that reacts with the eriodictyol-o-quinone to form a dark pink product absorbing at 508 nm, the lag disappeared. When the kinetic parameter was evaluated in the presence of MBTH (K_m= 0.6 m M ), the results was similar to those obtained without MBTH. Eriodictyol oxidation was inhibited by tropolone, which behaved as a classic competitive inhibitor (K_I= 15 μ M ). The inhibition results reported show that eriodictyol oxidation was strictly dependent on the presence of polyphenol oxidase. In addition, other oxidase activities, such as laccase and H₂O₂ independent phenol oxidase, were not detected in the enzyme extract.     

Comparative modeling approaches for personal exposure to particle-associated PAH

Several models for simulation of personal exposure (PE) to particle-associated polycyclic aromatic hydrocarbons (PAH) have been developed and tested. The modeling approaches include linear regression models (Model 1), time activity weighted models (Models 2 and 3), a hybrid model (Model 4), a univariate linear model (Model 5), and machine learning technique models (Model 6 and 7). The hybrid model (Model 4), which utilizes microenvironment data derived from time-activity diaries (TAD) with the implementation of add-on variables to account for external factors that might affect PE, proved to be the best regression model (R(2) for B(a)P = 0.346, p < 0.01; N = 68). This model was compared with results from two machine learning techniques, namely decision trees (Model 6) and neural networks (Model 7), which represent an innovative approach to PE modeling. The neural network model was promising in giving higher correlation coefficient results for all PAH (R(2) for B(a)P = 0.567, p < 0.01; N = 68) and good performance with the smaller test data set (R(2) for B(a)P = 0.640, p < 0.01; N = 23). Decision tree accuracies (Model 6) which assess how precisely the algorithm can determine the correct classification of a PE concentration range indicate good performance, but this is not comparable to the other models through R(2) values. Using neural networks (Model 7) showed significant improvements over the performance of hybrid Model 4 and the univariate general linear Model 5 for test samples (not used in developing the models). The worst performance was given by linear regression Models 1 to 3 based solely on home and workplace concentrations and time-activity data.     

Storage stability of a high dietary fibre powder from orange by-products

The goal of this investigation was to evaluate the effects of storage time and conditions on the physicochemical and microbiological properties of a high dietary fibre powder (HDFP). HDFP for this study was manufactured from orange juice industry by-products. The storage period was 11 months and samples were stored under vacuum or air exposure and under dark or light exposure. The HDFP is a stable product (based on chemical, microbiological and physicochemical properties) with large amounts of dietary fibre (71.62 ± 0.24 g 100 g⁻¹ dry sample) and polyphenols content (40.67 ± 0.45 mg g⁻¹ dry sample). Hesperidin is the major compound identified in HDFP (higher than 50% of total phenolic compounds). The packaging material used protects the HDFP only up to 6 months. After this time, the increase in moisture content decreases the quality of the product. The best storage conditions are packaging under vacuum and darkness. Both conditions preserve the colour of the fibres probably by means of avoiding pigment degradation.