This study aimed to determine the effect of different drying methods, namely hot air drying (HAD), vacuum drying (VD), ultrasound-assisted vacuum drying (USVD), and freeze drying (FD) on drying kinetic, total phenolic antioxidant activity, anthocyanin profile, in vitro-bioaccessibility of phenolic and color quality of raspberry samples. The drying time of the raspberry was 540, 720, and 1,140 min for USVD, VD, and HAD, respectively, indicating that USVD showed a significantly lower drying time than VD and HAD. The results of anthocyanin profile, TPC, CUPRAC, and DPPH analysis showed that FD had higher bioactive compound retention than other methods, followed by USVD. Cyanidin 3-O-sophoroside and Cyanidin 3-O-glucoside were found as the most abundant anthocyanin in raspberry samples. In the content of cyanidin 3-O-sophoroside, a loss of 78.33%, 15.41%, and 4.63% was observed in HAD, VD, and USVD, respectively. In vitro bioaccessibility of the VD and USVD were higher than FD and HAD. While the recovery value of TPC (%) was found for fresh raspberry as 3.09%, it was found as 6.79, 9.42, 8.46, and 5.58% for HAD, VD, USVD, and FD, respectively. Color quality was significantly affected by drying methods (p < .05), and USVD showed the lowest ∆E value. SEM analysis showed that less shrinkage and cell damage were observed in FD-and USVD-dried samples. This study suggested that USVD could be used as an alternative drying method since it showed lower drying time and shrinkage, higher bioactive compounds, and color retention than VD and HAD.Practical application: Raspberry is a popularly consumed fruit rich in bioactive compounds such as anthocyanin and vitamin C. Raspberry is a fruit with a low shelf life, sensitive to microorganisms and enzyme activities due to its high nutritional content and water activity. Drying is one of the most widely used methods to increase the shelf life of raspberries. It is crucial to find a suitable drying method because the bioactive components, color, and physical structure may change during drying. In this study, the effects of four drying methods on the total bioactive components, anthocyanin profile, microstructural structure, color, and phenolic antioxidant in vitro bioaccessibility of raspberry fruit were investigated. The study contains original data.
In this study, the phenolic compounds of oil mill waste (OMW) were extracted through the cloud point extraction method using lecithin as a surfactant. For this purpose, the effects of the equilibration temperature and time, pH, and the concentration of NaCl and lecithin on the recovery (%) of total phenolic content (TPC) were investigated by single‐factor experiments and further optimization of the process variables was carried out using the response surface analysis. The TPC values of OMW were 4830.50 ± 414.7 mg GAE/L, 7545.25 ± 766.89 TyE/L, and 5220.22 ± 390.68 HyTE/L. Antioxidant capacity values were 6892.05 ± 222.64 mg TE/L, 5010.54 ± 216.90 mg Fe2+E/L, and 4315.06 ± 237.73 mg TE/L. Hydroxytyrosol was the main phenolic compound identified with the value of 592.91 ± 8.39 mg/L followed by tyrosol at the level of 167.34 ± 2.23 mg/L. The optimum process conditions were determined as the temperature of 65°C, pH of 4.5, NaCl concentration of 10% (w:v), and lecithin concentration of 15% (w:v). The enriched lecithin obtained under the optimum conditions was used in the formulation of salad dressing, and its oxidative stability as compared to the sample prepared by control lecithin. The results obtained from oxidation kinetic parameters namely, IP, Ea, ΔH++∆S++, and ∆G++ showed that the salad dressings prepared with enriched lecithin provided higher oxidative stability than control lecithin. This study suggested that the use of lecithin in cloud point extraction could offer a new perspective for the recovery of phenolics from OMW without the application of solvent. Practical applications During the production of olive oil, waste with high biological value, rich in phenolic compounds, is generated. The recovery of phenolics from this waste and their use in the food industry is one of the current issues. Most of the studies on this subject are attempts to recover phenolics using solvents. The use of solvents limits the recovery efficiency of the OMW phenolics and their use in the food industry. Therefore, alternative methods are needed for the recovery of OMW phenolics. This study aimed to recover OMW phenolics with the cloud point extraction method, in which lecithin is used as a surfactant. Lecithin was used for this purpose for the first time in this study. Thus, it is aimed to produce enriched lecithin, which can be used directly in the food industry, as well as provide the recovery of olive oil waste phenolics without using solvents.
In recent years, interest in the consumption of dried goji berries has increased due to its high bioactive properties. Alternative drying methods that provide faster drying and better preservation of bioactive properties should be developed. This study aims to investigate the effect of different drying methods on the drying time and quality characteristics of the goji berry; namely, hot-air drying (HAD), ultrasound-assisted vacuum drying (USVD), vacuum drying (VD), freeze-drying (FD), and ultrasound-pretreated freeze-drying (USFD). The drying kinetic, total phenolic content, antioxidant capacity, phenolic profile, carotenoid profile, and color change of the goji berry fruit were determined. The drying times for VD, USVD, and HAD varied between 275–1330 min. USVD treatment showed faster drying behavior than the other two drying methods. The total phenolic content (TPC) value of dry samples varied between 1002.53–1238.59 mg GAE/g DM. USVD treatments exhibited a higher total phenolic content (TPC) value than all other drying methods. DPPH and CUPRAC values varied between 15.70–29.90 mg TE/g DM and 40.98–226.09 mg TE/g DM, respectively. The total color change (ΔE) value ranged between 4.59 and 23.93 and HAD dried samples showed the highest ΔE of all samples. The results of the phenolic profile were consistent with TPC analysis. HAD caused higher phenolic compound degradation than VD, USVD, and FD. The results of this study showed that different drying techniques significantly affected the drying rate and retention of bioactive components of the goji berry fruit, and the USVD and VD methods could be used as an alternative to the HAD method. This study concluded that USVD and FD could be considered as suitable drying methods and could be used as alternatives to HAD in the drying of goji berries.
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