Contents
01.12.2011.
Professional 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
01.12.2011.
Professional 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 Maina Mahungu
01.12.2011.
Professional 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
01.12.2011.
Professional paper
Effects of Pretreatments in Convective Dehydration of Rosehip (Rosa eglanteria)
The aim of this work was to experimentally determine drying curves for thin layer and bed drying of rosehip fruits, with and without pretreatments, to reduce processing times as a function of drying air operating variables, to propose dehydration kinetics of fruits and to determine its kinetic parameters for further use within drying simulation software. Fruits were pre-treated both chemically and mechanically, which included dipping the fruits in NaOH and ethyl oleate solutions; and cutting or perforating the fruit cuticle, respectively. Simulation models were then adopted to fit the kinetics drying data considering fruit volume shrinkage. These simple models minimized the calculation time during the simulation of deep-bed driers. Results show that pre-treatments reduced processing times up to 57%, and evaluated models satisfactorily predicted the drying of rosehip fruit. Effective mass diffusion coefficients were up to 4-fold greater when fruit was submitted to mechanical pretreatments.
Alejandra Mabellini, Elizabeth Ohaco, Carlos Alberto Márquez, Antonio De Michelis, Jorge Enrique Lozano
18.04.2012.
Original scientific paper
Effects of Pretreatments in Convective Dehydration of Rosehip (Rosa eglanteria)
The aim of this work was to experimentally determine drying curves for thin layer and bed drying of rosehip fruits, with and without pretreatments, to reduce processing times as a function of drying air operating variables, to propose dehydration kinetics of fruits and to determine its kinetic parameters for further use within drying simulation software. Fruits were pre-treated both chemically and mechanically, which included dipping the fruits in NaOH and ethyl oleate solutions; and cutting or perforating the fruit cuticle, respectively. Simulation models were then adopted to fit the kinetics drying data considering fruit volume shrinkage. These simple models minimized the calculation time during the simulation of deep-bed driers. Results show that pre-treatments reduced processing times up to 57%, and evaluated models satisfactorily predicted the drying of rosehip fruit. Effective mass diffusion coefficients were up to 4-fold greater when fruit was submitted to mechanical pretreatments.
Alejandra Mabellini, Elizabeth Ohaco, Carlos Alberto Márquez, Antonio De Michelis, Jorge Enrique Lozano
01.12.2011.
Professional paper
Challenges and Opportunities for the community of Food Sciences to contribute Towards a Society of Healthier Consumers and a Better World
Despite the tremendous scientific and technological achievements in the production of food, human well-being has not been served to a satisfactory extent. Millions of people are literally killing themselves by excessive eating or wrong use of food, leading to obesity and nutrition-related diseases. At the same time millions of people continue to suffer from lack of food, leading to starvation, malnutrition and death, often before reaching adult age. Parallel to striving for better-safer-healthier food, the community of Food Sciences is faced with the challenge to help educate the average consumer on how to select, handle, store and use food for safe and healthy eating. The need to reshape and reform public education to better serve this task is obvious. What is also obvious is the need for medical professionals to recognize healthy eating (and exercise) as the most valuable tool in preventive medical care. This perspective will concentrate on challenges and opportunities for Food Scientists/Engineers: to contribute towards a society of well-informed, self-protected, active and considerate citizens; to support public (food-related) education and actively participate in the fight against obesity and nutrition-related diseases; to intervene in decision making bodies and underline the importance of education on nutrition and food; to invent avenues and possibilities to contribute to the fight against world hunger; and all in all, to contribute towards a healthier world, a world that will not be split between hunger and obesity.
Harris N. Lazarides
01.12.2011.
Professional 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, R.P. Singh
01.12.2011.
Professional 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
01.12.2011.
Professional 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
Challenges and Opportunities for the community of Food Sciences to contribute Towards a Society of Healthier Consumers and a Better World
Despite the tremendous scientific and technological achievements in the production of food, human well-being has not been served to a satisfactory extent. Millions of people are literally killing themselves by excessive eating or wrong use of food, leading to obesity and nutrition-related diseases. At the same time millions of people continue to suffer from lack of food, leading to starvation, malnutrition and death, often before reaching adult age. Parallel to striving for better-safer-healthier food, the community of Food Sciences is faced with the challenge to help educate the average consumer on how to select, handle, store and use food for safe and healthy eating. The need to reshape and reform public education to better serve this task is obvious. What is also obvious is the need for medical professionals to recognize healthy eating (and exercise) as the most valuable tool in preventive medical care. This perspective will concentrate on challenges and opportunities for Food Scientists/Engineers: to contribute towards a society of well-informed, self-protected, active and considerate citizens; to support public (food-related) education and actively participate in the fight against obesity and nutrition-related diseases; to intervene in decision making bodies and underline the importance of education on nutrition and food; to invent avenues and possibilities to contribute to the fight against world hunger; and all in all, to contribute towards a healthier world, a world that will not be split between hunger and obesity.
Harris Lazarides
