Browsing by Author "Ugurlu, Serdar"

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A Comparison of Phenolic Compounds, Antioxidant Activity, and Α-Glucosidase Inhibitory Activities of Apple Chips Dried and Fried by Vacuum Combined Infrared Radiation
(Springer, 2024) Ugurlu, Serdar; Bakkalbasi, Emre
In this study, the effects of different drying (180-325 W and 100-400 mmHg) and frying (250-350 W and 400 mmHg) parameters on phenolic compounds, bioaccessibilities, antioxidant activities, and alpha-glucosidase inhibitory activities of apple chips dried and fried by vacuum-combined infrared radiation were investigated. Catechin (12.15-34.48 mg/kgDM), epicatechin (34.33-137.07 mg/kgDM), procyanidin B1 (14.07-30.05 mg/kgDM), procyanidin B2 (48.10-95.76 mg/kgDM), procyanidin C1 (14.95-42.97 mg/kgDM), chlorogenic acid (262.70-397.97 mg/kgDM), and rutin (0-5.94 mg/kgDM) were identified in apple chips. The phenolic content of apple chips increased with increasing infrared power during the drying and frying process. The phenolic contents of fried apple chips were generally higher than dried apple chips. However, the bioaccessibility rates of total flavan-3-ols in dried apple chips were higher than those of fried apple chips. It was determined that the initial total phenolic, flavonoid, and flavan-3-ol contents and antioxidant activity levels of the samples decreased after in-vitro gastrointestinal digestion. It was determined that all drying and frying samples showed higher alpha-glucosidase inhibitory activities (15.52-28.77 mg/mL) compared to acarbose (30.87 mg/mL). The apple chips dried and fried by infrared radiation had higher phenolic content, antioxidant activity, bioaccessibility, and alpha-glucosidase inhibitory activity than their counterparts (convectional drying and deep-fat frying, respectively). Vacuum-combined infrared drying and frying is a promising method to preserve the phenolic content, antioxidant, and antidiabetic activities of apple chips, especially at high temperature applications. Further research is needed on new designs for the production of fruit chips using infrared radiation and their effects on bioactive components.
Effect of Different Pre-Treatments and Storage Conditions on Some Quality Parameters of Apple Chips Dried by Vacuum Combined Two Side Infrared Radiation
(Pamukkale University, 2026) Ugurlu, Serdar; Bakkalba, Emre
The effect of ultrasound (0, 50, and 100% amplitude), ethanol (0, 50, and 100%), citric acid (0.75%), and their combined application on some quality parameters and microstructure of apple slices dried by novel vacuum combined two-way infrared dryer (275W, 400 mmHg) were investigated. In addition, the changes in quality parameters at 20, 30, and 40 degrees C during 8-month storage were evaluated. The different pretreatments, especially their combinations, had significantly affected the drying time, rehydration rate, color values (L*, a*, and b*), browning index, sugar content, 5-hydroxymethylfurfural (HMF), and sensory properties of the apple slices. The increasing ethanol concentration and ultrasound amplitude shortened the drying time from 110 min to 71 min. The high ethanol concentration combined with high ultrasound amplitude resulted in increased rehydration rate and decreased browning index, HMF, and general acceptance. As a result, the combination of ethanol containing (99.9%) 0.75% citric acid and 100% ultrasound amplitude was the best pretreatment method in terms of drying time, color, rehydration rate, browning index, and HMF content of apple chips.
Reduction of Bitterness in Green Walnuts by Conventional and Ultrasound-Assisted Maceration
(Elsevier, 2020) Ugurlu, Serdar; Okumus, Emine; Bakkalbasi, Emre
The efficiency of conventional and ultrasound-assisted maceration was investigated in comparison to reduce the bitterness of green walnuts. Conventional maceration was studied at room temperature for 6, 8 and 10 days while ultrasound-assisted maceration (20 kHz, %100 of amplitude) was performed at 36 degrees C for 6, 8, 10, 12, and 14 h. Phenolic content and antioxidant activity of green walnuts were decreased by reduction of bitterness. Phenolic content and antioxidant activity of green walnut jams prepared from debittered green walnuts by ultrasound-assisted maceration were higher than those of conventional maceration excluding ellagic acid only. Based on findings of sensory analyses, bitterness level was similar in green walnut jams prepared by ultrasound-assisted maceration for 12 h and conventional maceration for 6 days. On the other hand, green walnut jams processed by ultrasound-assisted maceration for 12 h led to the highest general acceptance. It was concluded that ultrasound-assisted maceration may provide better nutritional and sensory quality in green walnut jam. In addition, the time required for reduction of bitterness may be shortened from days to hours by ultrasound-assisted maceration.