Effect of oxygen availability and pH on the furan concentration formed during thermal preservation of plant-based foods

Thermally treated fruit- and vegetable-based foods are important contributors to the furan exposure of children and adults. Furan reduction by adding or removing precursors from the product has proven to be challenging because of major food constituents and interactions involved in the reaction pathways leading to furan formation. Instead of intervening at the precursor level, it might be more feasible to influence these formation pathways by adjusting the matrix properties of the product. As opposed to many previous literature sources, the present study investigated the effects of oxygen availability (normal versus reduced) and pH (acid versus low acid) on the furan formation in a real food system. Different combinations of both matrix properties were prepared in a reconstituted potato purée and subjected to a thermal treatment with a pasteurisation or sterilisation intensity. Irrespective of the addition of the furan precursors ascorbic acid, fructose and fatty acids, a considerable furan reduction was observed for the sterilised purées (F₁₂₁¹⁰ = 15 min) with either a reduced oxygen availability (0.1–1.8 mg l^–1) or at pH 3. The effects of both matrix properties were less pronounced in the pasteurised purées (P₉₀¹⁰ = 10 min), because of the lower furan concentrations. Even though the mechanisms of furan reduction for both types of matrix properties could not be fully elucidated, the results showed that lowering the oxygen concentration or pH prior to thermal processing offers a powerful, additional strategy for furan mitigation in thermally treated plant-based foods.     

Modifiable risk factors for coronary heart disease among young people in Addis Ababa

We report results of a cross-sectional survey of modifiable risk factors for coronary heart disease among young people (15-24 years of age) in Addis Ababa, conducted in 1994/95. A city-wide random sample of 1,436 (851 females and 585 males) young people participated in the study. Interviews using structured questionnaires, weight, height and blood pressure measurements were conducted using trained and supervised field workers. Current smoking was 11.8% for males and 1.1% for females. About 34% of the respondents consumed alcoholic beverages regularly, but 7.0% of these took more than 100 grams of alcohol per week. High fat intake and sedentary life-styles were registered in 4.5 and 8.4% of the respondents, respectively. About 6.0% of the females and 0.7% of the males were obese. The prevalence of elevated blood pressure (diastolic BP > 90 mmHG) was 7.1%. The prevalence of modifiable risk factors among young people in Addis Ababa indicates that there is need for initiation of primary preventive activities as soon as possible.     

Comparing the Impact of High-Pressure Processing and Thermal Processing on Quality of “Hayward” and “Jintao” Kiwifruit Purée: Untargeted Headspace Fingerprinting and Targeted Approaches

This study evaluated process-induced quality changes in kiwifruit purée of two commercial cultivars (green kiwifruit, “Hayward”, and gold kiwifruit, “Jintao”) treated by equivalent microbial safety-based processing: high-pressure processing (HPP; 600 MPa/3 min) and thermal processing (TP; P ^{85 °C} _{8.3 °C} = 5min). This comparative study was performed using both targeted, analyzing a priori selected quality attributes (color, sugars, organic acids, and vitamin C) and untargeted headspace-solid phase microextraction-gas chromatography-mass spectrometry approaches, combining multivariate data analysis techniques (partial least squares discriminant analysis and variable identification). HPP provided a better retention of color and vitamin C compared to TP. Sugar and organic acid were less affected by HPP and TP. Methyl and butyl esters were detected at higher amounts in both processed purée, compared to untreated purée. For processed samples, furanones, terpenes, and alcohols were detected at higher amounts after TP and aldehydes were detected at higher amount after HPP. Overall, the quality of HP-treated samples is clearly closer to that of fresh samples compared to thermally treated samples and HP treatment avoids the formation of typical temperature-induced compounds.     

Analytical study of heat and mass transfer in unsteady MHD radiant flow of Williamson nanofluid over stretching sheet with heat generation and chemical reaction

This paper presents the analytical study of heat and mass transfer in a two-dimensional time-dependent flow of Williamson nanofluid near a permeable stretching sheet by considering the effects of external magnetic field, viscous dissipation, Joule heating, thermal radiation, heat source, and chemical reaction. Suitable transformations are introduced to reformulate the governing equations and the boundary conditions convenient for computation. The resulting sets of nonlinear differential equations are then solved by the homotopy analysis method. The study on the effects of relevant parameters on fluid velocity, temperature, and concentration profiles is analyzed and presented in graphical and tabular forms. Upon comparison of the present study with respect to some other previous studies, a very good agreement is obtained. The study points out that the transfer of heat can substantially be enhanced by decreasing viscoelasticity of the fluid and the transfer of mass can be facilitated by increasing permeability of the stretching sheet.