scholarly journals Freeze-drying techniques for preserving aphids (Homoptera, Aphidodea)

1994 ◽  
Vol 5 (2) ◽  
pp. 105-113 ◽  
Author(s):  
Anders Albrecht
Keyword(s):  
Freeze Drying ◽  
Body Shape ◽  
Vacuum Drying ◽  
Drying Methods ◽  
Drying Time ◽  
Freeze Dried ◽  
Drying Techniques ◽  
Wax Coating ◽  
And Storage

Techniques for collection, preparation and storage of freeze-dried aphid samples, including galls, are described. Freeze-drying can be done with the aid of a home freezer, a drying agent, and suitable containers alone, but drying time can be reduced considerably with cheap and simple vacuum drying equipment. Freeze-drying methods have several advantages compared with traditional mounting techniques. Body shape, colours, wax coating and microsculpture are excellently preserved. The labour required per sample, for preparation as well as for identification, is reduced to a minimum, and complete colony samples can be stored as entities. Aspects of practical handling and study of freeze-dried aphid samples are discussed.

Dehydration and Rehydration of Cooked Mussels

2016 ◽  
Vol 12 (2) ◽  
pp. 173-180 ◽  
Author(s):  
G. Tribuzi ◽  
J. B. Laurindo
Keyword(s):  
Freeze Drying ◽  
Continuous Monitoring ◽  
Vacuum Drying ◽  
Drying Methods ◽  
Processing Temperature ◽  
Sample Weight ◽  
Freeze Dried ◽  
Drying Rates ◽  
Drying Curves ◽  
Water Holding

Abstract The objective of this study was to investigate different drying methods (oven-drying, vacuum-drying, and freeze-drying) applied to cooked mussels meat and the resulting rehydration and water-holding capacity. Drying curves were obtained using an online weighting system that allows continuous monitoring of sample weight during processing. The influence of the processing temperature on the drying rates and on the properties of dehydrated samples was assessed. In the studied conditions, freeze-drying presented higher drying rates and less structure alterations compared to the other drying methods investigated. The equilibrium rehydration capacity of oven-dried and vacuum-dried mussels was about 37 % lower than rehydration capacity of freeze-dried samples for the rehydration performed at 20 °C and about 21 % lower for rehydration performed at 80 °C.

scholarly journals Effects of Different Drying Methods on Drying Kinetics, Microstructure, Color, and the Rehydration Ratio of Minced Meat

Foods ◽  
2019 ◽  
Vol 8 (6) ◽  
pp. 216 ◽  
Author(s):  
Aslı Aksoy ◽  
Salih Karasu ◽  
Alican Akcicek ◽  
Selma Kayacan
Keyword(s):  
Quality Parameters ◽  
Drying Kinetics ◽  
Vacuum Drying ◽  
Drying Methods ◽  
Rehydration Ratio ◽  
Drying Time ◽  
Freeze Dried ◽  
Meat Samples ◽  
Drying Conditions ◽  
Minced Meat

This study aimed to investigate the effect of different drying methods, namely ultrasound-assisted vacuum drying (USV), vacuum drying (VD), and freeze-drying (FD), on the drying kinetics and some quality parameters of dried minced meat. In this study, USV was for the first time applied to the drying of minced meat. The USV and VD methods were conducted at 25 °C, 35 °C, and 45 °C. The different drying methods and temperatures significantly affected the drying time (p < 0.05). The USV method showed lower drying times at all temperatures. The rehydration values of the freeze-dried minced meat samples were higher than those obtained by the USV and VD techniques. The samples prepared using USV showed higher rehydration values than the vacuum dried samples for all temperatures. The effects of the different drying techniques and drying conditions on the microstructural properties of the minced meat samples were investigated using scanning electron microscope (SEM). The USV method resulted in higher porosity and a more open structure than the VD method. Total color differences (ΔE) for VD, USV, and FD were 8.27–20.81, 9.58–16.42, and 9.38, respectively, and were significantly affected by the drying methods and temperatures (p < 0.05). Higher drying temperature increased the ΔE value. Peroxide values (PV) significantly increased after the drying process, and samples treated with USV showed lower PV values than the VD treated samples. This study suggests that USV could be used as an alternative drying method for minced meat drying due to lower drying times and higher quality parameters.

scholarly journals Freeze-Drying of Sweet Peppers

1969 ◽  
Vol 54 (1) ◽  
pp. 133-148
Author(s):  
M. A. González ◽  
E. Díaz Negrón ◽  
H. Cancel ◽  
A. C. Rivera
Keyword(s):  
Shelf Life ◽  
Freeze Drying ◽  
Drying Rate ◽  
Microbial Count ◽  
Drying Time ◽  
Hot Air ◽  
Freeze Dried ◽  
And Storage ◽  
Index Of Quality ◽  
Platen Temperature

Studies were conducted to dehydrate garden sweet peppers by means of hot-air and freeze-drying. Sweet peppers have tough, leathery skins which makes escape of moisture difficult and prolongs drying time. Our data indicates that dehydration of half-cut or slitted fruit is accomplished either by conventional hot-air or by freeze-drying in reasonably shorter periods of time than whole fruit. Change in color or shape was not observed in sweet peppers during freezedrying. Great deterioration in the green color was observed in the samples dehydrated with hot-air at 165° F. The shelf-life of the freeze-dried product is superior to that of the conventionally hot-air dried product. For freeze-drying the sweet peppers within a reasonable period of time, and to obtain a product with shape and color similar to the fresh fruit, a platen temperature of 180° F. should be used during 2 hours and then reduced to 150° F. during the rest of the drying period. Heat treatment to inactivate microbial activity of sweet peppers prior to freeze-drying greatly reduces the microbial count and does not affect the drying rate, quality and shelf-life of the end product. Deterioration of sweet peppers during drying and storage is characterized by development of off-flavor and color. Because the measurement of off-flavor is difficult in a mild pungent fruit such as sweet peppers, these studies indicate that measurement of changes in color can be used as an index of quality.

scholarly journals Changes in Physicochemical Properties and Volatile Compounds of Roselle (Hibiscus sabdariffa L.) Calyx during Different Drying Methods

Molecules ◽  
2021 ◽  
Vol 26 (20) ◽  
pp. 6260
Author(s):  
Nurul Hanisah Juhari ◽  
Helle Jakobe Martens ◽  
Mikael Agerlin Petersen
Keyword(s):  
Moisture Content ◽  
Physicochemical Properties ◽  
Volatile Compounds ◽  
Freeze Drying ◽  
Cell Structure ◽  
Vacuum Drying ◽  
Drying Methods ◽  
Oven Drying ◽  
Sun Drying ◽  
Freeze Dried

Fresh roselle are high in moisture and deteriorate easily, which makes drying important for extending shelf-life and increasing availability. This study investigated the influence of different drying methods (oven-drying, freeze-drying, vacuum-drying, and sun-drying) on the quality of roselle calyx expressed as physicochemical properties (moisture content, water activity, soluble solids, color), volatile compounds, and microstructure. Oven-drying and freeze-drying reduced moisture content most while vacuum-drying and sun-drying were not as efficient. All drying methods except sun-drying resulted in water activities low enough to ensure safety and quality. Vacuum-drying had no impact on color of the dry calyx and only small impact on color of water extract of calyx. Drying reduced terpenes, aldehydes, and esters but increased furans. This is expected to reduce fruity, floral, spicy, and green odors and increase caramel-like aroma. Sun-drying produced more ketones, alcohols, and esters. Scanning electron microscopy revealed that freeze-drying preserved the cell structure better, and freeze-dried samples resembled fresh samples most compared to other drying techniques. The study concludes that freeze-drying should be considered as a suitable drying method, especially with respect to preservation of structure.

Drying characteristics and product quality of whole blueberry pulp in vacuum drying process

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Lijuan Zhao ◽  
Yonghuan Li ◽  
Hui Xie ◽  
Jianliang Zhang ◽  
Zhonghua Wu
Keyword(s):  
Freeze Drying ◽  
Heating Temperature ◽  
Convective Drying ◽  
Vacuum Drying ◽  
Operating Pressure ◽  
Drying Process ◽  
Drying Time ◽  
Drying Characteristics ◽  
Freeze Dried ◽  
Monomeric Anthocyanins

Abstract A pilot-scale vacuum dryer with visualization system was used to study the drying characteristics of the whole blueberry pulp. The heating temperature, operating pressure and initial material thickness had significant effects on the drying characteristics and the retentions of total monomeric anthocyanins and vitamin C in dried blueberry powder (P < 0.05). According the heat transfer mode inside the material, the whole drying process could be divided into three periods: the boiling drying period, the convective drying period, and the conductive drying period. Most of water in the material was evaporated in the boiling and convective drying period. Considering the drying characteristics and dried product quality comprehensively, an optimal drying condition for whole blueberry pulp were: heating temperature 70 °C, operating pressure 1 kPa, and the initial material thickness 5 mm. It further compared the drying time, nutrients retention, hygroscopicity and microstructure of the product obtained by vacuum and vacuum freeze drying. The drying time of vacuum drying (1.2 h) was much shorter than that of vacuum freeze drying (44 h); the retentions of the total monomeric anthocyanins and vitamin C in dried blueberry powder of vacuum drying (67.9, 46.7%) were lower than that of vacuum freeze drying (79.0, 85.8%); while the hygroscopicity of vacuum dried powder was less than that of the freeze-dried product. The SEM images displayed that the surface of the vacuum-dried blueberry powder was porous, and the vacuum freeze-dried product was lamellar.

scholarly journals Effect of Different Drying Techniques on the Resistant Starch, Bioactive Components, Physicochemical and Pasting Properties of Cardaba Banana Flour

2019 ◽  
Vol 23 (1) ◽  
pp. 35-42
Author(s):  
Adedolapo Ibironke Falodun ◽  
Helen Nwakego Ayo-Omogie ◽  
Olugbenga Olufemi Awolu
Keyword(s):  
Freeze Drying ◽  
Antioxidant Properties ◽  
Pasting Properties ◽  
Total Phenolic ◽  
Drying Methods ◽  
Crude Fibre ◽  
Freeze Dried ◽  
Drying Techniques ◽  
Flour Sample ◽  
Banana Flour

Abstract This study investigated the effect of different drying techniques on Cardaba banana flour. Cardaba banana was processed using sun, cabinet and freeze drying methods. The proximate, pasting, functional, starch profile and antioxidant properties of Cardaba banana flour were evaluated. The drying methods significantly (p ≤0.05) affected the chemical, functional, pasting and antioxidant properties of the Cardaba banana flour. Freeze dried (FD) flour sample had highest (6.69%) protein value, while sun dried (SD) flour sample had the lowest (6.13%). The crude fat of FD sample (2.38%) was not significantly different (p >0.05) from cabinet dried (CD) flour (2.38%) sample. However, sun dried sample crude fibre content was the highest (0.84%). In addition, drying methods significantly (p ≤0.05) affected the pasting characteristics of Cardaba banana flours. Results of functional properties showed that the drying methods had no effect on the least gelation properties of the flour. The resistant and total starch was highest in CD, and least in SD. Freeze drying produced flour high in indigestible carbohydrate compared to the other methods. Cardaba banana flour samples from all the drying methods showed substantive total phenolic, flavonoid, ABTS and DPPH contents. The drying methods employed significantly (p ≤0.05) affected the functional, chemical, pasting and antioxidants properties of Cardaba banana flours. However, the study indicated that freeze drying and cabinet drying produce flours with better properties.

Microstructural Characteristics of Dried Carrot Pieces and Real Time Observations during Their Exposure to Moisture

2007 ◽  
Vol 3 (4) ◽  
Author(s):  
Bronwen G Smith ◽  
Bryony J James ◽  
Christine A.L. Ho
Keyword(s):  
Cellular Structure ◽  
Freeze Drying ◽  
Environmental Scanning Electron Microscopy ◽  
Vacuum Drying ◽  
Environmental Scanning ◽  
Original Structure ◽  
Drying Methods ◽  
Microstructural Characteristics ◽  
Freeze Dried ◽  
Scanning Electron

The effects of different drying methods on the cellular structure of carrots were examined. Carrots were dried by vacuum drying, freeze drying and oven drying in combination with microwave pre-drying. Dried and fresh untreated samples were analysed by light microscopy and environmental scanning electron microscopy (ESEM). The cellular structure of vacuum dried as well as microwave pre-dried samples was found to be very different from that of fresh samples. Most, if not all, of the original microstructure was lost during drying with these techniques, though traces of original structure were preserved on external surfaces. Most of the original microstructure was preserved in the freeze dried carrot. ESEM was also used to observe the behaviour of the dried samples in an atmosphere of increasing humidity and showed that dried tissues did not regain their original cellular structure though some turgidity was regained by the freeze dried samples.

The Influence of Selected Drying Methods on the Physical Properties of Dried Apples cv. Jonagold Grown in Different Locations in Europe

2017 ◽  
Vol 13 (6) ◽  
Author(s):  
Anna Michalska ◽  
Krzysztof Lech ◽  
Adam Figiel ◽  
Grzegorz P. Łysiak
Keyword(s):  
Physical Properties ◽  
Freeze Drying ◽  
Geographical Origin ◽  
Raw Material ◽  
Convective Drying ◽  
Vacuum Drying ◽  
Drying Methods ◽  
Drying Time ◽  
Microwave Vacuum Drying ◽  
Apple Slices

Abstract The aim of the study was to determine the influence of four different growing locations of apples cv. ‘Jonagold’ in Europe on the drying kinetics and the physical properties of dried apple slices. The drying methods applied in the study (freeze-drying, convective drying, microwave-vacuum drying and combined drying) significantly affected the drying time, which was the shortest in the case of microwave vacuum drying. The geographical origin of the apples affected the chemical and physical properties of the raw material used for drying, and, consequently, the drying time. Water activity of dried samples was connected with the final dry matter, regardless of the geographical origin of the apples. Freeze-drying resulted in the lightest in colour products (L*), whereas microwave-vacuum dried products had the highest levels of yellow pigments (b*). The highest chroma and browning index values were noted for microwave-vacuum dried samples and were strongly influenced by the drying temperature. The mechanical properties of the apple slices were more dependent on the drying method and temperature of the process than on the geographical origin when the temperature exceeded 83 °C.

scholarly journals Effect of drying methods and extraction solvents on anti-amylase activity of selected medicinal plants

2021 ◽  
Vol 7 (1) ◽  
pp. 24-29
Author(s):  
CM Peries ◽  
◽  
SB Navarathne ◽  
WAJP Wijesinghe ◽  
AP Henagamage ◽  
...  
Keyword(s):  
Freeze Drying ◽  
Room Temperature ◽  
Amylase Activity ◽  
Alpha Amylase ◽  
Drying Methods ◽  
Leaf Extracts ◽  
Synthetic Drugs ◽  
Freeze Dried ◽  
Drying Techniques ◽  
Negative Side Effects

Presently, there is a blooming recognition in using the herbal medicine to treat the Diabetic mellitus due to the negative side effects of usage in synthetic drugs. The present study was aimed to evaluate the potential of anti-amylase activity of three different leaf extracts of Thebu (Costus speciosus), Kowakka (Coccinia grandis) and Masbadda (Gymnema sylvestre) following different drying techniques i.e; shade drying at room temperature, oven drying at 45 oC and freeze drying. Dried plant leaves were macerated with n-hexane, ethyl acetate and ethanol for 24 hours at room temperature separately. Obtained extracts were used to determine the anti- amylase activity. Results revealed that freeze dried ethanolic leaf extracts of all selected species showed the highest anti- amylase activity compared to the other drying methods. Further, there was a significant effect (p <0.05) on the drying techniques and solvents used to extract in inhibition of alpha amylase activity. Freeze dried C. speciosus and C. grandis ethanolic extracts displayed an effective inhibition against alpha amylase with an IC50 value of 4 mg/ml and 4.16 mg/ml respectively. Therefore, this study revealed that the drying methods significantly affected on the inhibition of alpha amylase enzyme. Freeze-drying was the most promising drying method and ethanol was the best solvent in extracting anti-amylase bioactive compounds from leaf extract of C. speciosus, C. grandis and G. sylvestre.

scholarly journals Effect of different drying techniques on the drying time and energy of blueberry

2021 ◽  
Vol 15 (1) ◽  
pp. 23-30
Author(s):  
Tamás Antal
Keyword(s):  
Freeze Drying ◽  
Optimal Solution ◽  
Physical Property ◽  
Vaccinium Corymbosum ◽  
Drying Methods ◽  
Rehydration Ratio ◽  
Drying Time ◽  
Hot Air ◽  
Freeze Dried ◽  
Time And Energy

Blueberries (Vaccinium corymbosum L.) were dried combining vacuum, infrared, hot-air and freeze drying technologies. In this paper, examined the drying time and energy consumption of dewatering methods. The rehydration as a physical property were evaluated in dried blueberries. Combination of vacuum dried and freeze dried blueberries had higher rehydration ratio, followed by the single freeze drying, combination of hot-air drying and freeze drying, and infrared-freeze drying methods. The performance evaluation indicated that combination drying of blueberries at two-stage infrared-freeze drying with 60°C and 15 min pre-drying reduced the drying time by 53.4%, besides consuming less energy (52.9%) compared to single freeze drying. Based on the results, primarily vacuum pre-drying, infrared pre-drying and freeze finish-drying may be the economical and optimal solution for dehydrating blueberries.

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