scholarly journals Convective Drying of Fresh and Frozen Raspberries and Change of Their Physical and Nutritive Properties

Foods ◽  
2019 ◽  
Vol 8 (7) ◽  
pp. 251 ◽  
Author(s):  
Zoran Stamenković ◽  
Ivan Pavkov ◽  
Milivoj Radojčin ◽  
Aleksandra Tepić Horecki ◽  
Krstan Kešelj ◽  
...  
Keyword(s):  
Ascorbic Acid ◽  
Freeze Drying ◽  
Color Change ◽  
Quality Criteria ◽  
Ascorbic Acid Content ◽  
Biologically Active ◽  
Convective Drying ◽  
Total Phenolic ◽  
Anthocyanin Content ◽  
Freeze Dried

Raspberries are one of Serbia’s best-known and most widely exported fruits. Due to market fluctuation, producers are looking for ways to preserve this fresh product. Drying is a widely accepted method for preserving berries, as is the case with freeze-drying. Hence, the aim was to evaluate convective drying as an alternative to freeze-drying due to better accessibility, simplicity, and cost-effectiveness of Polana raspberries and compare it to a freeze-drying. Three factors were in experimental design: air temperature (60, 70, and 80 °C), air velocity (0,5 and 1,5 m · s−1), and state of a product (fresh and frozen). Success of drying was evaluated with several quality criteria: shrinkage (change of volume), color change, shape, content of L-ascorbic acid, total phenolic content, flavonoid content, anthocyanin content, and antioxidant activity. A considerable influence of convective drying on color changes was not observed, as ΔE was low for all samples. It was obvious that fresh raspberries had less physical changes than frozen ones. On average, convective drying reduced L–ascorbic acid content by 80.00–99.99%, but less than 60% for other biologically active compounds as compared to fresh raspberries. Convective dried Polana raspberry may be considered as a viable replacement for freeze-dried raspberries.

scholarly journals The Effect of the Drying Method on the Quality of Dried Kiwi Slices

2017 ◽  
Vol 2 (1) ◽  
pp. 1 ◽  
Author(s):  
Kamyar Movagharnejad ◽  
Sepideh Pouya
Keyword(s):  
Antioxidant Activity ◽  
Ascorbic Acid ◽  
Acid Content ◽  
Freeze Drying ◽  
Color Change ◽  
Ascorbic Acid Content ◽  
Standard Methods ◽  
Freeze Dryer ◽  
Microwave Dryer

Abstract— Drying is known as a food preservation method which increases the food’s storage time by water reduction. Traditional drying consisted of open sun-drying, but different industrial dryers have been widely used in recent times. The new dryers consist of convective, infrared, ultrasound, freeze fluidized bed and freeze dryers. All of these dryers reduce the water content but under different mechanisms which leads to the end products with different qualities. In this study we aim to compare the difference in quality of kiwi fruit slices dried by three different dryers: 1. Convective tray dryer, 2. Microwave dryer and 3. Freeze dryer. The tray dryer experiments were conducted in two air temperatures of 60 and 80oC in the constant air velocity of 0.8 m/s. The microwave dryer operated in 3 output powers of 180, 270 and 360 W. The condenser temperature and pressure in the freeze dryer reduced to -50oC and 0.1 mbar, respectively. The operating conditions and time were regulated so that the moisture content of all dried samples reduced to nearly 10% in the wet basis. The three parameters of color change, ascorbic acid and antioxidant reduction were selected as the measuring criteria for the comparison of the product qualities. The experiments show that the freeze drying caused the minimum color change while the microwave drying in the maximum power of 360W caused the maximum amount of color change. The concentration of ascorbic acid was measured in the fresh fruits and dried samples by standard methods. The measurements proved that the ascorbic acid content of the freeze dried samples was 80% of the fresh fruits. The ascorbic acid content of other samples was much lower. The antioxidant activity of the dried samples and the fresh fruits was also measured by standard methods and the experimental data also showed that the freeze drying causes the minimum reduction in the antioxidant activity.

scholarly journals Storage Stability of Encapsulated Black Carrot Powder Prepared Using Spray and Freeze-Drying Techniques

2019 ◽  
Vol 7 (2) ◽  
pp. 261-267 ◽  
Author(s):  
Subramani Murali ◽  
Avinash Singh Patel ◽  
Abhijit Kar
Keyword(s):  
Half Life ◽  
Freeze Drying ◽  
Storage Stability ◽  
Color Change ◽  
Degradation Kinetics ◽  
Storage Period ◽  
Gum Arabic ◽  
Anthocyanin Content ◽  
Black Carrot ◽  
Freeze Dried

The present study was aimed to investigate the storage stability encapsulated black carrot powder obtained under the optimized conditions of spray drying of 150°C of inlet air temperature and freeze-drying with maltodextrin, gum arabic and tapioca starch as the combined carrier materials.Effect of two types of vial as a storing material viz., transparent and amber colored was used in this study and study was observed for the period of 90 days. Anthocyanin content, antioxidant activity, total color change and half-life period were monitored at 15 days interval throughout the storage period. The anthocyanins degradation rate followed first order kinetics. The storage half-life of spray and freeze-dried encapsulated material stored under airtight amber color vials was predicted up to 130 and 155 days with total degradation kinetics of 33% and 38%. However, the storage self-life spray and freeze-dried encapsulated material stored under airtight transparent vial was predicted up to 109 and 134 days with total antocyanin degradation of 37% and 43%, respectively.

scholarly journals Effect of Hot-Air and Freeze-Drying on the Quality Attributes of Dried Pomegranate (Punica granatum L.) Arils During Long-Term Cold Storage of Whole Fruit

Agriculture ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 493
Author(s):  
Adegoke Olusesan Adetoro ◽  
Umezuruike Linus Opara ◽  
Olaniyi Amos Fawole
Keyword(s):  
Cold Storage ◽  
Freeze Drying ◽  
Radical Scavenging ◽  
Storage Period ◽  
Total Phenolic ◽  
Anthocyanin Content ◽  
Total Anthocyanin ◽  
Hot Air ◽  
Freeze Dried

This study investigated the effect of hot-air and freeze-drying on the physicochemical, phytochemical and antioxidant capacity of dried pomegranate arils during long-term cold storage (7 ± 0.3 °C, with 92 ± 3% relative humidity) of whole fruit over a single experiment. Extracted arils were processed at monthly intervals during 12 weeks of cold storage of whole fruit. After the 12-week storage period, hot-air and freeze-dried arils showed the least (3.02) and highest (23.6) total colour difference (TCD), respectively. Hot-air dried arils also contained 46% more total soluble solids (TSS) than freeze-dried arils. During the storage of pomegranate fruit, total phenolic content (TPC) steadily increased from 20.9 to 23.9 mg GAE/100 mL and total anthocyanin content (TAC) increased from 6.91 to 8.77 mg C3gE /100 mL. Similarly, an increase in TPC and TAC were observed for hot-air (9.3%; 13%) and freeze-dried arils (5%; 5%), respectively. However, the radical scavenging activity (RSA) reduced by 8.5 and 17.4% for hot-air and freeze-dried arils, respectively, after 12 weeks of cold storage. Overall, the parameters such as colour, TPC and TAC as well as the lower degradation in RSA stability during storage showed distinct differences in quality when using the freeze-drying method, which is, therefore, recommended.

Color, microstructure, physicochemical, textural and sensory properties with the retention of secondary metabolites in convective-, microwave- and freeze-dried carrot (Daucus carota) slices

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Gulcin Yildiz
Keyword(s):  
Secondary Metabolites ◽  
Freeze Drying ◽  
Quality Characteristics ◽  
Sensory Properties ◽  
Convective Drying ◽  
Total Phenolic ◽  
Drying Methods ◽  
Content Type ◽  
Freeze Dried ◽  
The Impact

Purpose This work was undertaken to evaluate the impact of different drying methods (convective, microwave and freeze drying) on color, selected secondary metabolites (total phenolic substances, ascorbic acid, beta-carotene and antioxidant capacity), texture (hardness), sensory properties and microstructure of carrot slices.Design/methodology/approachConvective drying at three different temperatures (55, 65 and 75 °C), microwave drying at two different power levels (100 and 200 W) and freeze drying were applied.FindingsSignificant differences were found among fresh and dried-carrot slices. Convective-dried carrots showed better quality characteristics in comparison with microwave-dried carrots. The convective-dried carrots at 65 °C exhibited the highest retention of bioactive compounds and best color among all convective drying conditions. The microwave-dried carrot slices at lower power (100 W) showed higher quality characteristics compared to the dried carrots at 200 W. The freeze-dried carrots exhibited the highest retention of secondary metabolites, sensory properties and best color among all drying methods.Originality/value The results from this study are significant for the processing of dried carrots by optimizing the conditions to obtain a high-quality product. Overall, freeze drying is a promising application as shown in the present study by its capability to better retention carrot quality underlying color, sensory, texture, microstructure and secondary metabolites.

scholarly journals The Quality of Red Bell Pepper Subjected to Freeze-Drying Preceded by Traditional and Novel Pretreatment

Foods ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 226
Author(s):  
Katarzyna Rybak ◽  
Artur Wiktor ◽  
Dorota Witrowa-Rajchert ◽  
Oleksii Parniakov ◽  
Małgorzata Nowacka
Keyword(s):  
Freeze Drying ◽  
Bell Pepper ◽  
Total Phenolic ◽  
Thermal Methods ◽  
Drying Time ◽  
Freeze Dried ◽  
Dehydration Processes ◽  
Vacuum Freezing ◽  
Better Than

It has been demonstrated previously in the literature that utilization of PEF or a combination of a pulsed electric field (PEF) and ultrasounds (US) can facilitate dehydration processes and improve the quality of dried products even better than the application of thermal methods such as blanching. The aim of the study was to evaluate the quality of red bell pepper subjected to freeze-drying preceded by blanching or PEF or US treatment applied in a single and combined mode. Furthermore, the freeze-drying was preceded by shock freezing or vacuum freezing performed inside the freeze-dryer as a result of pressure drop during the first stage of freeze-drying. All of the analyzed technological variants enhanced the drying kinetics when compared to the intact material. Freeze-dried bell pepper subjected to non-thermal pretreatment exhibited higher vitamin C, total phenolic and carotenoids content than blanched material despite the fact that blanching reduced drying time the most compared to all other analyzed methods.

scholarly journals Antioxidant Potential in Different Parts and Callus ofGynura procumbensand Different Parts ofGynura bicolor

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Vijendren Krishnan ◽  
Syahida Ahmad ◽  
Maziah Mahmood
Keyword(s):  
Ascorbic Acid ◽  
Acid Content ◽  
Phenolic Content ◽  
Reducing Power ◽  
Ascorbic Acid Content ◽  
Total Phenolic ◽  
Total Flavonoid Content ◽  
Dpph Radical ◽  
Flavonoid Content ◽  
Different Parts

Plants from Gynura family was used in this study, namely,Gynura procumbensandGynura bicolor.Gynura procumbensis well known for its various medicinal properties such as antihyperglycaemic, antihyperlipidaemic, and antiulcerogenic; meanwhile,G. bicolorremains unexploited. Several nonenzymatic antioxidants methods were utilized to study the antioxidant capacity, which include ferric reducing antioxidant power (FRAP), 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay, total flavonoid content, total phenolic content, and ascorbic acid content determination. DPPH assay revealsG. procumbensshoot as the lowest (66.885%) andG. procumbensroot as the highest (93.499%) DPPH radical inhibitor. In FRAP assay, reducing power was not detected inG. procumbensleaf callus (0.000 TEAC mg/g FW) wherebyG. procumbensroot exhibits the highest (1.103 TEAC mg/g FW) ferric reducing power. Total phenolic content and total flavonoid content exhibited similar trend for both the intact plants analysed. In all antioxidant assays,G. procumbenscallus culture exhibits very low antioxidant activity. However,G. procumbensroot exhibited highest phenolic content, flavonoid content, and ascorbic acid content with 4.957 TEAC mg/g FW, 543.529 QEµg/g FW, and 54.723 µg/g FW, respectively. This study reveals thatG. procumbensroot extract is a good source of natural antioxidant.

Impacts of pulsed electric field and heat treatment on quality and sensory properties and microbial inactivation of pomegranate juice

2017 ◽  
Vol 23 (8) ◽  
pp. 668-680 ◽  
Author(s):  
Gulsun A Evrendilek
Keyword(s):  
Ascorbic Acid ◽  
Acid Concentration ◽  
Titratable Acidity ◽  
Sensory Properties ◽  
Pomegranate Juice ◽  
Total Phenolic ◽  
Anthocyanin Content ◽  
Linear Regression Models ◽  
Ascorbic Acid Concentration ◽  
Total Antioxidant

Synergistic effects of pulsed electric field+mild heat on quality properties of pomegranate juice were modeled using the best-fit multiple (non-) linear regression models with inactivation kinetics parameters of Escherichia coli O157:H7 and Staphylococcus aureus. No significant difference was detected between the control and the treated samples in terms of pH; °Brix; total antioxidant capacity; total monomeric anthocyanin content; total ascorbic acid concentration; and the sensory properties of flavor, taste, aftertaste, and overall acceptance ( p > 0.05). An exposure of 65.3 J and 40 ℃ caused an increase on conductivity; titratable acidity; L*, a*, and b* values; and a decrease of browning index, total phenolic content, total antioxidant capacity, total monomeric anthocyanin content, total ascorbic acid concentration, and in the sensory properties of color and sourness in pomegranate juice. The goodness-of-fit for the best-fit multiple (non-) linear regression models in descending order belonged to E. coli O157:H7 (92.98%), S. aureus (84.06%), color a* (83.9%), titratable acidity (81.3%), color L* (78.5%), color b* (78.3%), conductivity (74.8%), total phenolic content (74.1%), and total ascorbic acid concentration (64.74%), respectively. De and ze values for E. coli O157:H7 and S. aureus ranged from 105.64 to 1093.25 and from 79.18 to 1057.73 µs with 27.39 and 30.80 J, consequently.

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