Browsing by Author "Bulut, Nurullah"

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High-Pressure Processing of Traditional Hardaliye Drink: Effect on Quality and Shelf-Life Extension
(Mdpi, 2023) Atmaca, Bahar; Demiray, Merve; Evrendilek, Gulsun Akdemir; Bulut, Nurullah; Uzuner, Sibel
Hardaliye, as one of the oldest and lesser known traditional beverages, is produced using red grape pomace from wine production. This drink production is achieved through lactic acid fermentation, with the addition of sour cherry leaves and mustard seeds-either heat-treated, grinded, or whole-in various concentrations. Hardaliye has a very short shelf life; thus, efforts have recently been made to process hardaliye with novel processing technologies in order to achieve shelf-life extension. Therefore, the high-hydrostatic-pressure (HHP) processing of hardaliye was performed to determine its impact on important properties, including in microbial inactivation and shelf-life extension, with respect to a Box-Behnken experimental design. Maximum log reductions of 5.38 & PLUSMN; 0.6, 5.10 & PLUSMN; 0.0, 5.05 & PLUSMN; 0.2, and 4.21 & PLUSMN; 0.0 with HHP were obtained for Brettanomyces bruxellensis, total mesophilic aerobic bacteria, Lactobacillus brevis, and total mold and yeast, respectively. The processing parameters of 490 MPa and 29 & DEG;C for 15 min were found as the optimal conditions, with the response variables of an optical density at 520 nm and the inactivation of L. brevis. The samples processed at the optimal conditions were stored at both 4 and 22 & DEG;C for 228 d. While the non-treated control samples at 4 and 22 & DEG;C were spoiled at 15 and 3 d, the HHP-treated samples were spoiled after 228 and 108 d at 4 and 22 & DEG;C, respectively.
Prediction of Aspergillus parasiticus inhibition and aflatoxin mitigation in red pepper flakes treated by pulsed electric field treatment using machine learning and neural networks
(Elsevier, 2022) Akdemir Evrendilek, Gulsun; Bulut, Nurullah; Atmaca, Bahar; Uzuner, Sibel
Presence of aflatoxins in agricultural products is a worldwide problem. Because of their high heat stability and resistance to most of the food processing technologies, aflatoxin degradation is still a big challenge. Thus, efficacy of pulsed electric fields (PEF) by energies ranging from 0.97 to 17.28 J was tested to determine changes in quality properties in red pepper flakes, mitigation of aflatoxins, inactivation of aflatoxin producing Aspergillus parasiticus, reduction in aflatoxin mutagenity, and modelling of A. parasiticus inactivation in addition to aflatoxin mitigation. Maximum inactivation rate of 64.37 % with 17.28 J was encountered on the mean initial A. parasiticus count. A 99.88, 99.47, 97.75, and 99.58 % reductions were obtained on the mean initial AfG1, AfG2, AfB1, and AfB2 concentrations. PEF treated samples by 0.97, 1.36, 5.76, and 17.28 J at 1 μg/plate, 0.97, 1.92, 7.78, 10.80 J at 10 μg/plate, and 0.97, 1.92, 2.92, 4.08, 5.76, 4.86, 6.80, 9.60, 10.80, and 10.89 J at 100 μg/plate were not mutagenic. Modelling with gradient boosting regression tree (GBRT), random forest regression (RFR), and artificial neural network (ANN) provided the lowest RMSE and highest R2 value for GBRT model for the predicted inactivation of A. parasiticus, whereas ANN model provided the lowest RMSE and highest R2 for predicted mitigation of AfG1, AfB1, and AfB2. PEF treatment possess a viable alternative for aflatoxin degradation with reduced mutagenity and without adverse effect on quality properties of red pepper flakes.