Food Engineering / Gıda Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/12
Browse
8 results
Search Results
Article Citation - WoS: 9Citation - Scopus: 11Authentication of Pomegranate Juice in Binary and Ternary Mixtures With Spectroscopic Methods(Elsevier, 2023) Aykaç, Başak; Çavdaroğlu, Çağrı; Özen, BanuFruit juices are among the most commonly adulterated food products and especially pomegranate juice as a high value product is mixed with different adulterants for unfair economic profit. It was aimed to investigate the performances of UV–visible and Fourier-transform infrared (FTIR) spectroscopies combined with chemometric methods to determine adulteration of pomegranate juice with dark colored sour cherry and black carrot juices. Binary and ternary mixtures of pomegranate juice with 2 adulterants were prepared at 5–25% levels. After various data transformations, both spectroscopic data of authentic and adulterated samples were evaluated with different chemometric classification tools. Classification models with 97% correct classification rate for validation set were obtained both for UV–visible and FTIR spectral data. Accurate predictions of adulterant concentration were also achieved with chemometric models using both spectroscopic data. These spectroscopic techniques provide rapid and accurate prediction of pomegranate juice adulteration in binary and ternary mixtures with dark colored juices.Article Citation - WoS: 59Citation - Scopus: 71Microbial Safety and Shelf Life of Uv-C Treated Freshly Squeezed White Grape Juice(John Wiley and Sons Inc., 2015) Ünlütürk, Sevcan; Atılgan, Mehmet ReşatThe effects of UV-C irradiation on the inactivation of Escherichia coli K-12 (ATCC 25253), a surrogate of E. coli O157:H7, and on the shelf life of freshly squeezed turbid white grape juice (FSWGJ) were investigated. FSWGJ samples were processed at 0.90 mL/s for 32 min by circulating 8 times in an annular flow UV system. The UV exposure time was 244 s per cycle. The population of E. coli K-12 was reduced by 5.34 log cycles after exposure to a total UV dosage of 9.92 J/cm2 (1.24 J/cm2 per cycle) at 0.90 mL/s flow rate. The microbial shelf life of UV-C treated FSWGJ was extended up to 14 d at 4 °C. UV exposure was not found to alter pH, total soluble solid, and titratable acidity of juice. There was a significant effect (P < 0.05) on turbidity, absorbance coefficient, color, and ascorbic acid content. Furthermore, all physicochemical properties were altered during refrigerated storage. The microbial shelf life of FSWGJ was doubled after UV-C treatment, whereas the quality of juice was adversely affected similarly observed in the control samples. Practical Applications: UV-C irradiation is a non-thermal method used for processing of fruit juices with a minimal or no changes in flavor, essential nutrients, and vitamins. Fresh grape juice is a popular drink, usually consumed at summer time due to many beneficial health effects. Although thermal pasteurization is widely used for extending the shelf life of fruit juices, it causes a "cook taste" in grape juice. The applicability of UV-C irradiation as an alternative to thermal pasteurization was investigated. It is concluded that UV-C treatment can be used for extending the shelf life of fresh grape juice.Article Citation - WoS: 22Citation - Scopus: 33Uv-C Irradiation of Freshly Squeezed Grape Juice and Modeling Inactivation Kinetics(John Wiley and Sons Inc., 2014) Ünlütürk, Sevcan; Atılgan, Mehmet ReşatUV inactivation kinetics of freshly squeezed turbid white grape juice (FSTGJ) treated with an annular flow UV reactor by applying UV dosages ranging from 0 to 116.7J/mL, at three different flow rates (0.90, 1.75 and 3.70mL/s), were modeled by using log-linear, Weibull, Hom and modified Chick-Watson models. FSTGJ was circulated five times in the UV system, i.e., UV exposure time was 20.33min during processing. The populations of Escherichia coli K-12, lactic acid bacteria (LAB) and foodborne yeasts were reduced by 3.759, 4.133 and 1.604log cfu/mL, respectively, after exposure to UV dosage of 116.7J/mL at the lowest flow rate. The inactivation kinetics of foodborne yeasts were best described by the modified Chick-Watson model, with the least root mean squared error (RMSE=0.001, R2=0.999). Besides, the inactivation kinetics of E.coli K-12 and LAB were best fitted by Weibull model (R2=0.999). Additionally, when the UV exposure time was increased up to 32.5min (i.e., eight cycles), UV-C treatment of FSTGJ resulted in 5.341log cfu/mL reduction in E.coli K-12, which meets the Food and Drug Administration requirement of a 5log reduction of microorganisms in fruit juices. Practical Applications Consumer demand for high-quality fruit juice with fresh-like characteristics has markedly expanded in recent years. UV-C irradiation is a nonthermal method and allows the processing of fruit juices with a minimal or no changes in flavor, essential nutrients and vitamins. Although thermal pasteurization is the most convenient way of increasing the shelf life of fruit juices, it causes a "cook taste" in grape juice. So, in this study, the application of UV-C irradiation to process grape juice was investigated. The shape of the microbial inactivation curve is sigmoidal in UV treatment. Therefore, different kinetic models (e.g., log-linear, Weibull, Hom and modified Chick-Watson) are applied to describe the inactivation kinetics of Escherichia coli K-12, lactic acid bacteria and foodborne yeasts. Kinetic parameters (e.g., k and D) and models can be used for the development of UV-C irradiation process to ensure microbial safety in juice products.Article Citation - WoS: 38Citation - Scopus: 49Antimicrobial Activity of Grape Seed Extract on Alicyclobacillus Acidoterrestris Dsm 3922 Vegetative Cells and Spores in Apple Juice(Academic Press Inc., 2015) Molva, Çelenk; Baysal, Ayşe HandanThe present study evaluated the antimicrobial activity of grape seed extract (GSE) against Alicyclobacillus acidoterrestris vegetative cells and spores in apple juice (pH 3.82, °Brix 11.3) during storage at 37°C. After 336h, reductions in the cell numbers were 3.14, 3.55, 3.8, 4.1, and 4.63 logCFU/mL in the apple juice with 0.23, 0.45, 0.9, 1.8, and 3.6% of GSE, respectively. The Weibull was found to be the best fitted model for cell inactivation kinetics (R2>0.988). Moreover, the spores produced on different sporulation media (potato dextrose agar, malt extract agar, Bacillus acidoterrestris agar, and Bacillus acidocaldarius agar) were treated with GSE (0-1.9%, v/v). While control spores in apple juice without GSE increased by 2.2-2.6logCFU/mL within the first 48h, 0.9% and 1.8% of GSE inhibited the growth from all spore suspensions. Finally, scanning electron microscopy (SEM) indicated that the main target of the GSE may be the membrane of A. acidoterrestris cells leading to leakage of cellular constituents and may prevent the development of spores into vegetative cells. This study highlights the potential use of the by-products of the fruit juice/beverage industry as natural antimicrobials to inhibit the growth of A. acidoterrestris. © 2014 Elsevier Ltd.Article Citation - WoS: 29Citation - Scopus: 31Evaluation of Bioactivity of Pomegranate Fruit Extract Against Alicyclobacillus Acidoterrestris Dsm 3922 Vegetative Cells and Spores in Apple Juice(Academic Press Inc., 2015) Molva, Çelenk; Baysal, Ayşe HandanThis research evaluated the antimicrobial activity of commercial pomegranate extract (POMELLA®, PE) against Alicyclobacillus acidoterrestris vegetative cells and spores (approximately 105 log CFU/mL) in apple juice (pH 3.82, °Brix 11.3) during storage at 37°C. After 240h, the cell counts were reduced from the initial log count (CFU/mL) by 2.84, 3.26, 3.32, 3.46 and 3.56 in the apple juice with PE at the concentrations of 2.5, 5, 10, 20 and 40μg/mL, respectively. On the other hand, counts of the control reached 7.36 log CFU/mL after 24h. The Weibull model satisfactorily described the survival curves of cell inactivation kinetics (R2 > 0.983). While the growth of all spores obtained from different sporulation media (potato dextrose agar, malt extract agar, Bacillus acidoterrestris agar, and Bacillus acidocaldarius agar) was inhibited in the apple juice with PE (2.5-40μg/mL), the control spores increased by 1.9-2.2 log CFU/mL after 336h. Based on the scanning electron microscopy (SEM) imaging, vegetative cells indicated substantial damage and spore germination was inhibited in the apple juice with PE. The results showed that PE can have possible uses as a natural antimicrobial to control the growth of A.acidoterrestris vegetative cells and spore germination in the apple juice. © 2015 Elsevier Ltd.Article Citation - WoS: 14Citation - Scopus: 16Effect of Sporulation Medium on Wet-Heat Resistance and Structure of Alicyclobacillus Acidoterrestris Dsm 3922-Type Strain Spores and Modeling of the Inactivation Kinetics in Apple Juice(Elsevier Ltd., 2014) Molva, Çelenk; Baysal, Ayşe HandanAlicyclobacillus acidoterrestris is a spoilage bacterium in fruit juices leading to high economic losses. The present study evaluated the effect of sporulation medium on the thermal inactivation kinetics of A. acidoterrestris DSM 3922 spores in apple juice (pH3.82±0.01; 11.3±0.1 °Brix). Bacillus acidocaldarius agar (BAA), Bacillus acidoterrestris agar (BATA), malt extract agar (MEA), potato dextrose agar (PDA) and B. acidoterrestris broth (BATB) were used for sporulation. Inactivation kinetic parameters at 85, 87.5 and 90°C were obtained using the log-linear model. The decimal reduction times at 85°C (D85°C) were 41.7, 57.6, 76.8, 76.8 and 67.2min; D87.5°C-values were 22.4, 26.7, 32.9, 31.5, and 32.9min; and D90°C-values were 11.6, 9.9, 14.7, 11.9 and 14.1min for spores produced on PDA, MEA, BATA, BAA and BATB, respectively. The estimated z-values were 9.05, 6.60, 6.96, 6.15, and 7.46, respectively. The present study suggests that the sporulation medium affects the wet-heat resistance of A. acidoterrestris DSM 3922 spores. Also, the dipicolinic acid content (DPA) was found highest in heat resistant spores formed on mineral containing media. After wet-heat treatment, loss of internal volume due to the release of DPA from spore core was observed by scanning electron microscopy. Since, there is no standardized media for the sporulation of A. acidoterrestris, the results obtained from this study might be useful to determine and compare the thermal resistance characteristics of A. acidoterrestris spores in fruit juices. © 2014 Elsevier B.V.Article Citation - WoS: 30Citation - Scopus: 42Degradation of Various Fruit Juice Anthocyanins by Hydrogen Peroxide(Elsevier Ltd., 2005) Özkan, Mehmet; Yemenicioğlu, Ahmet; Cemeroglu, BekirDegradation kinetics of anthocyanins was studied in sour cherry nectar, pomegranate and strawberry juices at high hydrogen peroxide (H2O 2) concentrations (9.31-27.92 mmol l-1) at 10-30°C and in only sour cherry nectar at low H2O2 concentrations (0.23-2.33 mmol l-1) at 20°C. Degradation of anthocyanins followed the first-order reaction kinetics. Sour cherry anthocyanins were the most resistant to H2O2, followed by pomegranate and strawberry anthocyanins. Degradation of anthocyanins was also studied in sour cherry nectar and pomegranate juice in the presence of ascorbic acid at 60 and 80 mg l-1 concentrations at 20°C. At 80 mg level, ascorbic acid significantly accelerated the degradation of anthocyanins in sour cherry nectar at 4.65, 6.98 and 9.31 mmol l-1 H2O2 concentrations. In contrast, ascorbic acid at both 60 and 80 mg levels protected the anthocyanins from degradation by H2O2 in pomegranate juice.Article Citation - WoS: 38Citation - Scopus: 43Degradation Kinetics of Anthocyanins From Sour Cherry, Pomegranate, and Strawberry Juices by Hydrogen Peroxide(John Wiley and Sons Inc., 2002) Özkan, Mehmet; Yemenicioğlu, Ahmet; Asefi, N.; Cemeroglu, BekirDegradations were studied at different hydrogen peroxide (H2O2] concentrations (9.31 to 27.92 mmol. L-1] over a range of 10 ° to 30 °C. Degradation of anthocyanins by H2O2 was described by first-order function. Comparison of t1/2 values revealed that sour cherry anthocyanins were the most resistant to H2O2, followed by pomegranate and strawberry anthocyanins. Thus, the removal of residual H2O2 from the juice contact surfaces of aseptically packaged strawberry juices should be controlled more carefully to prevent anthocyanin degradation. Respective Ea values were between 9.4 to 11.1, 9.5 to 11.4, and 11.4 to 12.2 kcal.mol-1; and Q10 values between 1.59 to 2.22, 1.62 to 2.05, and 1.76 to 2.36 for strawberry, sour cherry, and pomegranate anthocyanins.