Current issue

Issue image

Volume 13, Issue 2, 2024

Online ISSN: 2182-1054

Volume 13 , Issue 2, (2024)

Published: 18.10.2024.

Open Access

All issues

More Filters

Contents

18.04.2012.

Original scientific paper

Influence of Organic Material and Biofilms on Disinfectant Efficacy Against Listeria monocytogenes

The effects of organic material and biofilm formation on the efficacy of Suma Tab D4 chlorine tablets and Suma Bac D10 quaternary ammonium compound (QAC) against Listeria monocytogenes was determined in suspension and on stainless steel and polystyrene surfaces according to standard disinfectant test methodology. Exposure to 200 and 740 mg L-1 QAC and to 150 mg L-1 active chlorine resulted in a > 5.0 log10 CFU mL-1 and > 5.0 log10 CFU/coupon reduction of six L. monocytogenes strains within one minute, in suspension tests, and on stainless steel surfaces, respectively. Additionally, there was a reduction by as much as 5 log10 CFU/coupon or 5 log10 CFU/well of reference strains EGDe and Scott A biofilms within five minutes on stainless steel and polystyrene surfaces. Organic material, added as bovine serum albumin at 0.3% (w/v) completely prevented the inactivation of L. monocytogenes in 150 mg L-1 chlorine, while reductions of only 0.6 +- 0.1 log10 CFU mL-1 were recorded in the presence of UHT milk at 3% (v/v). In contrast, reductions of 5 log10 CFU mL-1 were recorded within one minute on exposure to 740 mg L-1 QAC in the presence of 0.3% (w/v) bovine serum albumin and within two minutes in the presence of 20 % (v/v) UHT milk. Although Suma D4 chlorine tablets and Suma Bac D10 QAC are effective listericidal agents at recommended concentrations, Suma Tab D4 chlorine efficacy against L. monocytogenes is impaired by the presence of low concentrations of organic material, while Suma Bac D10 QAC maintains its listericidal activity in high organic loads.

Hilda Nyati, Rijkelt Beumer, Stijn Van der Veen, Wilma Hazeleger, Tjakko Abee

18.04.2012.

Original scientific paper

Determination of Phenolic Compounds in Wines

Wine contains natural antioxidants such as phenolic compounds also known as bioactive compounds. Samples of commercially available Greek wines were analyzed in order to determine this phenolic content. For the analysis, Reversed Phase-High Performance Liquid Chromatography (RP-HPLC) coupled with a multiwavelength Ultraviolet/visible (UV/vis) detector was used. The most abundant phenolic substances detected were (+)-catechin (13.5-72.4 mg L-1 ), gallic acid (0.40-99.47 mg L-1) and caffeic acid (0.87-33.48 mg L-1). The principal component analysis (PCA) technique was used to study differentiation among wines according to their production area. Red wines contained more phenolic substances than white ones. Differences of the phenolic composition in wines of the same cultivar were investigated too.

Charalampos Proestos, Athanasios Bakogiannis, Michael Komaitis

18.04.2012.

Original scientific paper

Kinetics of Hydrolyzing Isolated Soy Protein by an Endopeptidase and its Conceptual Application in Process Engineering

A response study and the effects of different parameters (pH, temperature and enzyme dose) on kinetics of isolated soy protein hydrolysis by a trypsin-like endopeptidase (TL1) were conducted. Degree of hydrolysis (%DH) data varied at different times under different hydrolysis conditions. Fitting the kinetics data to Michaelis-Menten kinetics model did not result in reasonable kinetic parameters, which implied that Michaelis-Menten kinetics was invalid for such a hydrolysis process. A kinetics model proposed by (Gonzalez-Tello, Camacho, Jurado, Paez, & Guadix, 1994) was found to fit the kinetics curve well and resulted in acceptable model parameters. A simple simulation example was performed to demonstrate the concept of how the kinetics equation could be applied in process engineering.

zebin wang, Jason Lombardi, Jessica Shaffer, Ted Wong

18.04.2012.

Original scientific paper

The Use of Maltodextrin Matrices to Control the Release of Minerals from Fortified Maté

The aim of this research was to study the sensorial acceptance of a fortified food containing different minerals (calcium, magnesium and iron) and to determine the actual quantities present (bioaccessibility) when extracted in maté. A sensorial analysis was performed to compare sensorial quality of fortified and non-fortified maté. Although panelists identified differences between the fortified and non-fortified maté, only 3% of them commented on an unpleasant flavor. Sequential extraction assays were performed simulating maté consumption under laboratory conditions. Profile concentration diminished sharply after the second extraction. Magnesium was found to be completely extracted in the first 500 mL. Calcium and Iron were extracted in a very low percentage (29% and 25%, respectively). The outlet rate of the minerals was fitted to two models, and a good fitness (p < 0:001) in all cases was obtained.

Miguel E. Schmalko, Myrian G. Acuña, Miguel Schmalko

01.12.2011.

Professional paper

Changes and Perspectives in Food Studies

Food Studies represent the bases for multidisciplinary knowledge in food science, food engineering, food management, and how to use these scientific bases in a food worldwide context. Teaching and learning must be adapted to the new students, to the new tools, considering the cost of studies and equipment. The international availability of raw materials, the diversity of cultures, tastes and habits must be taken into account in the controlled food processes. Food engineering must be taught with reference to nutrition, health and security, but also to packaging, logistics, international rules, management of water, energy, wastes and cost. So how do we teach the present and future food engineers, to help them to acquire and build their own knowledge, to develop curiosity, an open mind and team work? How do we teach them to use, in an efficient way, computers, data bases, the internet, but also to learn and practice in the lab, on pilot equipment, in the plant during long internships? How do we give them the desire to conceive, to create, to manage, to communicate and to continue to learn during their professional life? International networks of universities, with associated people from research and industry, with teachers in elementary and secondary schools, with students, represent a main factor for reciprocal knowledge and exchanges, to preserve and use diversity to develop new ideas for teaching and learning. The objectives are to contribute to the development of our society, to feed in an harmonized way the world made of human beings, consumers, and workers in industry, research and universities.

Elisabeth Dumoulin

01.12.2011.

Professional paper

Characterization of sponge cake baking in an instrumented pilot oven

The quality of baked products is the complex, multidimensional result of a recipe, and a controlled heating process to produce the desired final properties such as taste, colour, shape, structure and density. The process of baking a sponge cake in a convective oven at different air temperatures (160-180-220 °C) leading to the same loss of mass was considered in this study. A special mould was used which allowed unidirectional heat transfer in the batter. Instrumentation was developed specifically for online measurement of weight loss, height variation and transient temperature profile and pressure in the product. This method was based on measuring heat fluxes (commercial sensors) to account for differences in product expansion and colour. In addition, measurement of height with a camera was coupled to the product mass to calculate changes in density over time. Finally, combining this information with more traditional measurements gave a better understanding of heat and mass transfer phenomena occurring during baking.

Alain Sommier, Elisabeth Dumoulin, Imen Douiri, Christophe Chipeau

18.04.2012.

Original scientific paper

High-Quality Learning Environments for Engineering Design: Using Tablet PCs and Guidelines from Research on How People Learn

A team of several faculty members and graduate students at Universidad de las Amricas Puebla is improving engineering design teaching and learning by creating richer learning environments that promote an interactive classroom while integrating formative assessment into classroom practices by means of Tablet PCs and associated technologies. Learning environments that are knowledge-, learner-, community-, and assessment-centered as highlighted by the How People Learn framework, have been developed. To date, the redesign of the undergraduate course entitled Introduction to Engineering Design has signicantly (p<0.05) increased student participation; formative assessment and feedback are more common and rapid; and instructors are utilizing the information gained through real-time formative assessments to tailor instruction to meet student needs. Particularly important have been opportunities to make student thinking visible and to give them chances to revise, as well as opportunities for "what if" thinking.

Enrique Palou, Lourdes Gazca, Juan Antonio Díaz García, José Andrés Rojas Lobato, Luis Geraldo Guerrero Ojeda, José Francisco Tamborero Arnal, María Teresa Jiménez Munguía, Aurelio López-Malo, Juan Manuel Garibay

18.04.2012.

Original scientific paper

Treatment of Olive Mill Wastewater and the Use of Polyphenols Obtained After Treatment

Olive mill wastes are signicant environmental problem especially in Mediterranean areas where they are generated in huge quantities in a short period of time. They are phytotoxic materials because of their high phenol, lipid and organic acid concentrations, but these wastes also contain valuable resources that could be recycled such as a large proportion of organic matter and a wide range of nutrients. The effluent from olive oil mills contains a large amount of polyphenols that have antioxidant properties. The market value of these antioxidants is high and they are commonly used in the food, cosmetics, pharmaceutics and chemical industries. For the management of olive mill wastewater (OMW) and other olive residues, various treatment methods can be used. Many scientists work on more efficient and cheaper treatment alternatives. Due to the great variety of compounds in the waste, several technologies to remove the harmful compounds for the environment should be used single or together. Some of the most used OMW treatments are drying / evaporation, forced evaporation, thermal treatment, centrifugation-ultraltration, electrocoagulation, composting, lagooning, adsorption, powdered activated carbon, filtration, sand filtration, membrane filtration, ultrafiltration, precipitation / flocculation, distillation, electrolysis, co-composting, advanced oxidation processes (AOPs) such as ozonation, hydrogen peroxide / ferrous iron oxidation (the so-called Fentons reagent). Several OMW treatment technologies have been developed aiming at the removal of the main toxic organic compounds. A lot of factors must be considered to choose the treatment methods among them the investment, required area, specic training of the workers, noise and odour emissions and seasonality of production.

semih otles, Ilknur Selek

18.04.2012.

Original scientific paper

Effect of Egg White Utilization on the Physico-Chemical and Sensory Attributes of Protein-rich Yoghurt

High protein yoghurt was made from whole milk, fortified with egg white (30% v/v) and skim milk powder at 12% (w/v). Different yoghurt mixes, with albumin content of 15%, 30% and 45% (v/v), were prepared. The control was made from whole milk, fortified with skim milk powder at 12% (w/v). The blended premixes were pasteurized at 74ºC for 4 seconds, cooled and then inoculated with 3% (w/v) Direct Vat Set yoghurt starter culture at 45ºC. After fermentation for 3 hours in a water bath maintained at 46+-1C, product was cooled to 5ºC and then stored for 24 hours. The effect of the fortification on physico-chemical and sensory properties was investigated. Protein content increased to 8.50% at 45% egg white utilization. Susceptibility to wheying was reduced in egg-white fortified samples, without signicant difference in sensory attributes of the test samples compared to the control. Sensory analysis showed that yoghurt fortified with 45% egg white was organoleptically acceptable. The yoghurt was rated as having better sensory appeal as compared to the control.

Lilian A Gogo, Kennedy O. Gogo, Peter L. Shalo, Symon Mahungu

18.04.2012.

Original scientific paper

Moisture Adsorption and Thermodynamic Properties of California Grown Almonds (Varieties: Nonpareil and Monterey)

Moisture adsorption characteristics of California grown almonds (Nonpareil: pasteurized and unpasteurized almonds; Monterey: pasteurized, unpasteurized and blanched almonds) were obtained using the gravimetric method over a range of water activities from 0.11 to 0.98 at 7-50ºC. The weights of almonds were measured until samples reached a constant weight. The relationship between equilibrium moisture content and water activity was established using the Guggenheim-Anderson-de Boer model. The diffusion coefficient of water in almond kernels was calculated based on Ficks second law. The monolayer moisture value of almonds ranged from 0.020 to 0.035 kg H2O kg-1 solids. The diffusion coefficient increased with temperature at a constant water activity, and decreased with water activity at a constant temperature. The thermodynamic properties (net isosteric heat, differential enthalpy and entropy) were also determined. The net isosteric heat of adsorption decreased with the increasing moisture content, and the plot of differential enthalpy versus entropy satisfied the enthalpy-entropy compensation theory. The adsorption process of almond samples was enthalpy driven over the range of studied moisture contents.

Li Zuo Taitano, Paul Singh

Indexed by