The aim of this study was to determine the effect of different concentrations of grapeseed oil (GSO) addition (0.5%, 1% and 1.5% w/v) to yoghurt milk on survival of starter bacteria, and physicochemical, textural and sensory properties of set-type yoghurts during the 21 days of storage. Moreover, radical scavenging activity (RSA) and total phenolic content (TPC) of yoghurts were investigated. Yoghurts containing GSO exhibited significantly higher TPC and RSA as compared to control yoghurts. The results obtained from this investigation show that GSO has a potential to be used as a food supplement to improve health-promoting properties of yoghurt.

In this study, the evaporation of apple juice was completed with ohmic heating to eliminate some problems with conventional evaporation methods. Ohmic evaporation (OE) was performed at different voltage gradients (13–17 V/cm) for determining electrical conductivity (EC), Hydroxymethylfurfural (HMF), and the total phenolic content (TPC) changes. The voltage gradient affected the total consumed energy, average power, and specific water removal ratio (SWRR) values (p < .05). The shortest time was obtained at 17 V/cm, while the longest time was 13 V/cm during the OE process. The EC value varies between 0.19–0.85 S/m for the voltage gradients. EC and current values increase with temperature until boiling starts, then decrease, and the EC value tends to increase slightly. The TPC value ranged between 587.4–716,4 mg GAE/100 g and was higher at OE than in the conventional process. As a result, the OE process preserves the TPC value of apple juice better while shortening the processing time. Novelty impact statement The ohmic evaporation process is an alternative method that can be preferred in concentrating fruit juices with consuming less energy and obtaining higher quality products. In addition, considering the phenolic distribution, it was determined in this study that the products were better preserved in the ohmic evaporation process. It is predicted that it will provide important data for both pilot and industrial designs for the establishment of any ohmic evaporation systems.

Bu çalışmada piyasadan alınmış olan Nar (Punica granatum L.), Keçiboynuzu (Ceratonia siliqua L.), Karadut (Morus nigra L.), Dut (Morus alba L.) ve farklı bölgelerden alınan Üzüm (Vitis vinifera L.) pekmezlerinin farklı yöntemlerle antioksidan aktivitelerinin ölçümü yapılmıştır. Pekmez çeşitlerinin radikal süpürme gücü DPPH ve ABTS yöntemleri ile, Toplam Fenolik Madde tayini ise Folin metoduyla belirlenmiştir. Çalışma sonucunda yapılan istatistiksel analizlerde ABTS yok etme aktivitesi bakımından Nar, Keçiboynuzu, Mardin Üzüm pekmezi, Batman Üzüm pekmezi ve Karadut sırasıyla % 99.34±0.18, % 99.22±0.2, % 98.92±0.45, % 98.71±0.13, % 97.77± 0.4 ile yüksek aktivite gösterirken, Dut pekmezi % 94.65± 0.2 ile en düşük aktiviteyi göstermiştir. DPPH radikal giderme aktivitesi bakımından en yüksek değer % 82.32±0.6 ile Nar, en düşük değer ise % 43.33±0.8 ile Üzüm pekmezidir. Toplam fenolik madde açısından en yüksek aktiviteye 748.74±14.43 mg GAE/100 g ile Keçiboynuzu pekmezi sahip iken, en düşük aktiviteye ise 166.14±6.8 mg GAE/100 g ile Mardin üzüm pekmezinin sahip olduğu tespit edilmiştir. Yapmış olduğumuz bu çalışmada Keçiboynuzu pekmezinin toplam fenolik madde içeriğinin diğer pekmezlerin değerinin iki katından daha fazla olması bu pekmezin antioksidan aktivitesinin daha güçlü olduğunu ortaya koymaktadır.

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