Modeling of simultaneous heat and mass transfer during convective oven ring cake baking

The convective oven ring cake baking process was investigated experimentally and numerically as a simultaneous heat and mass transfer process. The mathematical model described previously by the authors for cup cake baking was modified to simulate ring cake baking. The heat and mass transfer mechanisms were defined by Fourier’s and Fick’s second laws, respectively. The implicit alternating direction finite difference technique was used for the numerical solution of the representative model. Prior to the utilization of the developed model in predicting the temperature and moisture profiles for ring cake baking, the results of the numerical model were compared with analytical results involving only heat or mass transfer with constant thermo-physical properties. Excellent agreement was observed. The numerical temperature and moisture contents predicted by the model were compared with the experimental profiles. They agreed generally reasonably well with the experimental temperature and moisture profiles.     

Distribution of simple phenols,phenolic acids and flavonoids in Turkish monovarietal extra virgin olive oils for two harvest years

Monovarietal extra virgin olive oils extracted from six dominant and economically important Turkish olive cultivars (memecik, erkence, domat, nizip-yaglik, gemlik, ayvalik) were examined for their simple phenolics, phenolic acids and flavonoid compounds over 2005 and 2006 harvest years. Total phenol contents, oxidative stabilities and chromatic ordinates as colour parameters were also measured. The most typical phenolic compounds that were identified in both years are hydroxytyrosol, tyrosol, vanillic acid, p-coumaric acid, cinnamic acid, luteolin, and apigenin. Multivariate data were analysed by principal component and partial least square-discriminant analyses. It was observed that phenolic profiles of olive oils depended highly on harvest season. In addition, oils of different olive cultivars have different distribution of phenols. No significant correlation was observed between oxidative stability and phenolic compounds. Increase in peroxide value over an accelerated oxidation period of 11 days showed weak correlations with total phenol content, vanillin, syringic acid and colour parameter a^∗, as 0.56, 0.55, −0.42, and 0.51, respectively, in terms of correlation coefficient r.     

Effect of Steam Baking on Acrylamide Formation and Browning Kinetics of Cookies

Abstract: Effects of baking method and temperature on surface browning and acrylamide concentration of cookies were investigated. Cookies were baked in natural and forced convection and steam‐assisted hybrid ovens at 165, 180, and 195 °C and at different times. For all oven types, the acrlyamide concentration and surface color of cookies increased with increasing baking temperature. Significant correlation was observed between acrylamide formation and browning index, BI, which was calculated from Hunter L, a, and b color values, and it showed that the BI may be considered as a reliable indicator of acrylamide concentration in cookies. Acrylamide formation and browning index in cookies were considered as the first‐order reaction kinetics and the reaction rate constants, k, were in the range of 0.023 to 0.077 (min^?1) and 0.019 to 0.063 (min^?1), respectively. The effect of baking temperature on surface color and acrylamide concentration followed the Arrhenius type of equation, with activation energies for acrylamide concentration as 6.87 to 27.84 kJ/mol; for BI value as 19.54 to 35.36 kJ/mol, for all oven types. Steam‐assisted baking resulted in lower acrylamide concentration at 165 °C baking temperature and lower surface color for all temperatures. Steam‐assisted baking is recommended as a healthy way of cooking providing the reduction of harmful compounds such as acrylamide for bakery goods, at a minimal level, while keeping the physical quality. Practical Application: The kinetics of acrylamide formation and browning of cookies will possibly allow definition of optimum baking temperatures and times at convectional and steam‐assisted baking ovens. The kinetic model can be used by developing baking programs that can automatically control especially a new home‐scale steam‐assisted hybrid oven producing healthy products, for the use of domestic consumers.     

Use of ozone for the preparation of functional silk fibroin-based biomaterial loaded with bioactive compounds for biomedical applications

Silk fibroin (SF) can be used for the preparation of porous functional biomaterials due to its biocompatibility, biodegradability, and minimal in?ammatory reactions. High porosity and homogenous interconnected pore structure is a challenge for the preparation of porous biomaterials. Porous SF foam materials can be formed by bubbling inert gases through aqueous solutions and subsequent freeze drying process. In this study, SF foam structures were prepared by first purging ozone gas and then freeze drying of this ozone-treated aqueous SF solution. Resulting porous materials were efficiently loaded with plant extract for the preparation of functional biomaterials having antimicrobial properties. The interactions of SF with ozone led to chemical modifications that improved both foaming and hydrophobic properties. Intensive ozone treatment caused the crystallinity degree of untreated SF to decrease from 48% to 42%. Ozone treatment also resulted in a significant reduction in surface tyrosine content from 55% to 43%. The use of ozone gas for the preparation of SF foam material enhanced the adsorption capacity of phenolic compounds. The enhancement in the adsorption of phenolic compounds on SF foam structure can be attributed to the oxidation-dependent increase in hydrophobicity.     

Microbiological quality of artisanal Sepet cheese

Microbial diversity in milk and in cheese itself affects the biochemical and sensory characteristics of artisanal cheeses. In this study, the microflora of Sepet cheese, which is a traditional artisanal cheese in Turkey, was investigated. Average lactococci, lactobacilli, enterococci, yeast, mould, coliform, psychrotrophic and total aerobic bacteria, presumptive Staphylococcus aureus counts were; 7.31 ± 1.08, 7.19 ± 1.02, 6.84 ± 0.92, 3.19 ± 1.40, 0.84 ± 0.89, 2.18 ± 1.81, 4.92 ± 1.15, 7.53 ± 1.13 and 1.25 ± 1.70 log cfu/g, respectively. Staphylococci, coliform and mould counts were less than 1.00 log cfu/g at the end of ripening, which was at around 6–8 °C for 3 months. According to phenotypic and genotypic identifications, isolates were closely related to Lactobacillus plantarum, Weisella confusa, Weisella paramesenteroides, Pediococcus pentasaceous, Enterococcus casseliflavus, Enterococcus durans and Enterococcus faceium. This study provides baseline data on the microflora of traditional artisanal Sepet cheese, which is a prerequisite for a successful scale up to industrial production.     

Classification of Turkish olive oils with respect to cultivar,geographic origin and harvest year,using fatty acid profile and mid-IR spectroscopy

Fatty acid composition and mid-infrared spectra of olive oils in combination with chemometric techniques were used in the classification of Turkish olive oils with respect to their varieties, growing location and harvest year. In particular, olive oil samples belonging to five different cultivars were obtained from the same orchard in the middle part of Aegean region and two of these varieties were also received from another orchard in northern part of the same region of Turkey in two consecutive harvest years. Evaluation of nine different fatty acid compositions with principal component analysis revealed clear differentiation with respect to variety, geographical origin and harvest year. On the other hand, mid-infrared spectra also achieved varietal and seasonal discrimination to some extent, but differentiation is not as clear as that obtained using fatty acid compositions.     

Spray Drying of Yogurt: Optimization of Process Conditions for Improving Viability and Other Quality Attributes

Plain yogurt was subjected to spray drying to determine the optimum processing conditions that yield maximum survival ratio of lactic acid bacteria, maximum overall sensory attributes, minimum color change, and acceptable moisture content. The inlet (150–180°C) and outlet air temperatures (60–90°C) and the feed temperature (4–30°C) were the independent factors. A pilot-scale spray dryer was used to conduct a set of drying experiments where the process conditions were selected according to central composite rotatable design (CCRD). The resulting yogurt powder at each condition was also subjected to the measurement of some physical properties (water activity, titratable acidity [lactic acid, %] and pH) to determine the effects of spray-drying conditions. The morphological structure of the powder was inspected by scanning electron microscopy (SEM) analysis. Optimization by the application of the desirability function method resulted in air inlet temperature of 171°C, air outlet temperature of 60.5°C, and feed temperature of 15°C as the optimum processing condition. The mathematical optimum condition was experimentally verified.     

Comparison of energy inputs in glasshouse double crop (fall and summer crops) tomato production

The study examines energy use patterns and the relationship between energy inputs and yield for double crop (fall and summer) glasshouse tomato production in Antalya province, where is one of the most important greenhouse centres in Turkey. The data of the study was retrieved from 37 fall and 25 summer glasshouse tomato producers via face to face survey in 2007. The research findings revealed energy use values for inputs such as manure, electricity, chemical fertilizer and fuel. While the average yield per hectare is 25025.4 kg for enterprises involved in tomato production in fall, it is 22392.9 kg for summer production. The overall energy consumption is higher in fall production with 81362.2 MJ ha^?1 in comparison to summer production 63023.2 MJ ha^?1. In addition, the specific energy requirement is 3521.2 MJ t^?1 and 2814.4 MJ t^?1 for fall and summer production in order and the energy efficiency was found out to be 0.31 kg MJ^?1 and 0.36 kg MJ^?1 respectively. Finally, the energy relationship was tested using the production relationship. The findings indicated that direct energy sources are effective in tomato yield for both of the two seasons. More clearly, the most significant energy input was electrical energy for summer production and a combination of electrical energy, human power and machinery for fall production. Yet, excess and unconscious use of chemical ingredients in glasshouse tomato production was confirmed as energy derived from chemical drugs leaded a declination in the yield for fall season. Therefore, the paper revealed energy relationship for double crop glasshouse tomato production in Antalya, being a reference for similar production methodologies.     

Structural characterization and dehydration kinetics of Kırka inderite mineral: Application of non-isothermal models

Coats-Redfern, Arrhenius, Ozawa, Kissinger, and Doyle non-isothermal kinetic models were used to calculate the dynamic kinetic parameters for dehydration reaction of Mg-borate mineral, inderite (K?rka — Turkey) based on thermogravimetric analysis, derivative thermogravimetric analysis and differential thermal analysis. Dehydration experiments were carried out at different heating rates of 2, 5, 10, 15, and 20 °C/min in a pure nitrogen atmosphere. Structural and morphological properties have been characterized by X-Ray diffraction, Fourier transform-infrared spectroscopy, Scanning electron microscopy-energy dispersive spectroscopy, and Inductively coupled plasma-optical emission spectroscopy techniques.