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Öğe APRICOT NECTAR PROCESSING BY PULSED ELECTRIC FIELDS(Taylor & Francis Inc, 2013) Evrendilek, Gulsun Akdemir; Altuntas, Julide; Sangun, Mustafa Kemal; Zhang, Howard Q.Application of pulsed electric fields to process apricot nectar by determining the pH,. Brix, total acidity, conductivity, color, non-enzymatic browning index, concentration of mineral ions, and retention of ascorbic acid and beta carotene as well as inactivation of Escherichia coli O157:H7, Listeria monocytogenes, Staphylococcus aureus, Pseudomonas syringae subs. syringae, Erwinia carotowora, Penicillum expansum, and Botrytis cinerea was explored in this study. Processing of apricot nectar did not cause a significant difference in measured attributes (p > 0.05). However, inactivation of all microorganisms was significantly increased with increased electric field strength and treatment time (p <= 0.05). Microbial inactivation data fit both the Weibull distribution and log-logistic model.Öğe Effects of pulsed electric field processing on the quality and microbial inactivation of sour cherry juice(Wiley, 2010) Altuntas, Julide; Evrendilek, Gulsun Akdemir; Sangun, Mustafa Kemal; Zhang, Howard Q.P>Pulsed electric fields (PEF) processing of sour cherry juice with the measurement of pH, boolean OR Brix, titratable acidity, conductivity, colour (L*, a* and b*), nonenzymatic browning index, metal ion concentration, total ascorbic acid and total antocyanin content as well as microbial inactivation were searched in the study. Applied PEF treatment parameters did not cause any significant difference on measured properties of sour cherry juice (P > 0.05). On the other hand, inactivation of Escherichia coli O157:H7, Staphylococcus aureus, Listeria monocytogenes, Erwinia carotowora, Pseudomonas syringae subs. syringae, Botrytis cinerea and Penicillum expansum significantly increased with increased electric field strength and treatment time (P < 0.05). It was revealed that PEF is a viable option to process sour cherry juice with significant amount of microbial inactivation and without adversely affecting important physical and quality parameters.Öğe Inactivation of Penicillum expansum in sour cherry juice, peach and apricot nectars by pulsed electric fields(Academic Press Ltd Elsevier Science Ltd, 2008) Evrendilek, Gulsun Akdemir; Tok, Fatih M.; Soylu, E. Mine; Soylu, SonerInhibitory effects of pulsed electric fields (PEF) on Penicillum expansum inoculated into sour cherry juice, apricot and peach nectars were determined based on germination tube elongation, spore germination and light and scanning electron microscopy (SEM) observations in this study. After inoculation of rate, juice/nectar samples with P. expansum spores at the level of 10(5)-10(6) cfu/mL, the samples were processed by bench scale PEF pulse generator as a function of differing electric field strengths (0, 13, 17, 20, 23, 27, 30 and 34 kV/cm) and processing times (0, 62, 94, 123, 163, 198 and 218 mu s). Results revealed that with an increase in electric field strength and processing time, germination tube elongation and spore germination rate were completely inhibited. Light and SEM observations revealed considerable morphological alterations in fungal conidia such as cytoplasmic coagulation, vacuolations, shrinkage and protoplast leakage. PEF processing of juice/nectars was demonstrated to be effective in inactivating P. expansurn. To our knowledge, this is the first study confirming the inhibitory effects of PEF on germination tube elongation and spore germination rate of P. expansum in fruit juice/nectars. (C) 2008 Elsevier Ltd. All rights reserved.Öğe Modelling stochastic variability and uncertainty in aroma active compounds of PEF-treated peach nectar as a function of physical and sensory properties, and treatment time(Elsevier Sci Ltd, 2016) Evrendilek, Gulsun Akdemir; Avsar, Yahya Kemal; Evrendilek, FatihEffects of pulsed electric field (PEF) processing on 28 aroma active compounds, and four physical and eight sensory properties of peach nectar were explored using the best-fit multiple linear regression (MLR) models and Monte Carlo simulations as a function of the treatment times of 0, 66, 131, and 210 mu s. The PEF treatment time of 131 mu s on average led consistently to the least loss of most compounds. Significantly enhanced or no significant changes in the sensory properties were found as a function of the PEF treatment times. The most influential sensory predictor of the 28 MLR models was flavour, while the aroma compound most influential on the sensory properties of aftertaste, flavour, sweetness, and overall acceptance was octadecanoic acid. Monte Carlo simulations were used for the probabilistic assessments of stochastic variability and uncertainty associated with aroma active compounds of PEF-treated peach nectar. (C) 2015 Elsevier Ltd. All rights reserved.Öğe PROCESSING OF PEACH NECTAR BY PULSED ELECTRIC FIELDS WITH RESPECT TO PHYSICAL AND CHEMICAL PROPERTIES AND MICROBIAL INACTIVATION(Wiley, 2011) Altuntas, Julide; Evrendilek, Gulsun Akdemir; Sangun, Mustafa K.; Zhang, Howard Q.Applicability of pulsed electric fields (PEFs) to process peach nectar as a function of electric field strength and treatment time with respect to microbial inactivation and measurement of physical and chemical properties of peach nectar was evaluated. No significant difference was detected in terms of pH, degrees Brix, titration acidity (TA), conductivity, color (L*, a* and b*), nonenzymatic browning index (NBI), metal ion concentration, ascorbic acid content and beta carotene concentration between control and PEF-treated peach nectar samples (P > 0.05). On the other hand, Escherichia coli O157:H7, Staphylococcus aureus, Listeria monocytogenes, Erwinia carotowora, Pseudomonas syringae, Botrytis cinerea and Penicillum expansum were significantly inactivated (P <= 0.05). PEF can successfully be applied to peach nectar with significant amount of microbial inactivation without a significant adverse effect on physical and chemical properties.Öğe Production of a dry sausage from African catfish (Clarias gariepinus, Burchell, 1822)(Wiley, 2008) Oksuz, Abdullah; Evrendilek, Gulsun Akdemir; Calis, Muzaffer Seufi; Ozeren, AkifProduction of a dry sausage from African catfish and determination of its microbial, chemical and sensory properties during a 70-day storage at both 4 and 22 degrees C were prompted. pH of the samples at 4 and 22 degrees C did not significantly change during the storage (P > 0.05). Moisture content of the samples was 74%, and reduced to 45% at 4 degrees C and to 22% at 22 degrees C. Protein content of the samples was 20.71%, and increased to 42.5% at 4 degrees C and to 57.99% at 22 degrees C. Total lipid content was 4.5%, and increased to 10.98% at 4 degrees C and to 15.68% at 22 degrees C (P < 0.05). Microbial analyses showed that there was a significant reduction in total aerobic mesophilic and psychrotrophilic bacteria, total mould and yeast, total lactic acid bacteria, total Enterobacteriaceae and Staphylococcus aureus counts at both 4 and 22 degrees C (P < 0.05). Samples stored at 4 degrees C had significantly higher sensory ratings than that of the samples stored at 22 degrees C (P < 0.05).Öğe Pulsed electric fields: Processing system, microbial and enzyme inhibition, and shelf life extension of foods(Ieee-Inst Electrical Electronics Engineers Inc, 2007) Min, Seacheol; Evrendilek, Gulsun Akdemir; Zhang, Howard Q.Pulsed electric field (PEF) nonthermal food processing has been of growing interest owing to because of its excellent potential in providing consumers with microbiologically safe and fresh quality foods. Application of high-voltage electric fields at a certain level for a very short time by PEF not only inhibits pathogenic and spoilage microorganisms but also results in the retention of flavor, aroma, nutrients, and color of foods. This paper provides the most current information about PEF food processing. It reviews the systems for PEF processing and its effects on the inhibitions of microorganisms and enzymes and sensory and nutritional properties of foods. Regulatory issues of PEF processing are discussed as well.Öğe Survival of Escherichia coli O157:H7 in yogurt drink, plain yogurt and salted (tuzlu) yogurt(Blackwell Publishing, 2007) Evrendilek, Gulsun AkdemirThe survival of Escherichia coli O157:H7 at 4 and 22 degrees C in yogurt drink, plain yogurt and salted yogurt (yogurt native to Hatay, Turkey) was studied. Total aerobic plate count (TPC), total mould and yeast count, pH and titratable acidity during the storage period were measured. pH and TPC count of the samples at 22 degrees C were significantly higher than those of samples at 4 degrees C (P < 0.01). E. coli O157:H7 survived in the products at both 4 and 22 degrees C, whereas survival of E. coli O157:H7 was significantly lower at 4 degrees C than at 22 degrees C (P < 0.05). Multiple linear regression models were used to determine factors affecting the survival of E. coli O157:H7.
