Quality evaluation of different pre-treatments and combined convective-freeze drying of sour cherry (Prunus Cerasus L.)

2014 ◽  
Vol 10 (1) ◽  
pp. 17-33
Author(s):  
T. Antal ◽  
L. Sikolya ◽  
B. Kerekes

In this study, the influences of various pre-treatments and combined drying (CD) on the drying kinetics and quality parameters of sour cherry were investigated. Prior to freeze drying (FD), sour cherry was pre-treated by blanching in boiling water (100 °C, 3 and 6 min), immersion in sugar solution (20% w/w, 10 and 20 min) and blanching (100 °C) in sugar solution (20% w/w, 3 and 6 min). Freeze-drying of raw samples was taken as a control. Combined drying (CD) can be accomplished in two distinct ways: freeze drying assisted with hot-air drying application (FD-HAD) and hot-air drying followed by freeze drying (HAD-FD). The quality of the dried sour cherry was evaluated in terms of water activity, color, texture and rehydration. Our research results have shown that all of the pre-treatments can effectively reduce the freeze drying time, the best treatment methods are FD-HAD, HAD-FD and blanching in boiling water (6 min). CD involves much less drying time and energy consumption than conventional freeze drying methods. The highest values of hardness and rehydration were found in blanching in sugar solution with water at 100 °C for 6 min. The better color retention was observed for samples pre-treated with blanching in boiling water (6 min).

Molecules ◽  
2021 ◽  
Vol 26 (3) ◽  
pp. 598
Author(s):  
Graziana Difonzo ◽  
Antonella Aresta ◽  
Pietro Cotugno ◽  
Roberta Ragni ◽  
Giacomo Squeo ◽  
...  

Olive pomace is a semisolid by-product of olive oil production and represents a valuable source of functional phytocompounds. The valorization of agro-food chain by-products represents a key factor in reducing production costs, providing benefits related to their reuse. On this ground, we herein investigate extraction methods with supercritical carbon dioxide (SC-CO2) of functional phytocompounds from olive pomace samples subjected to two different drying methods, i.e., freeze drying and hot-air drying. Olive pomace was produced using the two most common industrial olive oil production processes, one based on the two-phase (2P) decanter and one based on the three-phase (3P) decanter. Our results show that freeze drying more efficiently preserves phytocompounds such as α-tocopherol, carotenoids, chlorophylls, and polyphenols, whereas hot-air drying does not compromise the β-sitosterol content and the extraction of squalene is not dependent on the drying method used. Moreover, higher amounts of α-tocopherol and polyphenols were extracted from 2P olive pomace, while β-sitosterol, chlorophylls, and carotenoids were more concentrated in 3P olive pomace. Finally, tocopherol and pigment/polyphenol fractions exerted antioxidant activity in vitro and in accelerated oxidative conditions. These results highlight the potential of olive pomace to be upcycled by extracting from it, with green methods, functional phytocompounds for reuse in food and pharmaceutical industries.


Author(s):  
Dat Q Tran

Dried vegetables are considered convenient for storage, transportation and preservation. The different drying techniques could influence the quality of resulting products. This study aimed to evaluate the effects of three distinguish drying methods as hot-air drying, foam-mat drying and microwave drying on the color retention and chlorophyll of green vegetables powder. Fresh spinach(Spinacia oleraceaL.), celery (Apium graveolensL.), Malabar spinach (Basella albaL.) were dried by different methods: hot air at 60oC, foam-mat at 60oC and microwave at 270 W until the samples reached approximately 9% of moisture content (wb). The drying time of the dried samples by microwave, foam-mat and hot-air method were 60, 210 and 240 min, respectively. Foam-mat dried vegetables were found to have the best quality in terms of color and the residual chlorophyll content. The findings suggest that foam-mat drying is promising in dried vegetable processing


2018 ◽  
Vol 192 ◽  
pp. 03023
Author(s):  
Natthacha Chaloeichitratham ◽  
Pornkanya Mawilai ◽  
Thadchapong Pongsuttiyakorn ◽  
Pimpen Pornchalermpong

In this study, the effects of two drying methods: hot-air and freeze drying for Thai green curry paste in a terms of drying time and qualities have been investigated. The hot-air drying was carried out in tray dryer at temperature of 50, 60 and 70 °C. The freeze drying was carried out in freeze dryer at freezing temperature of -20°C, primary drying temperature of -10°C and secondary drying temperature of 50°C. Moisture content, water activity, colour, bulk density, and total phenolic content (TPC) were determined in samples. Freeze dried sample had significantly (p<0.05) lower moisture content, water activity, bulk density, total colour difference and browning index than hot air dried samples. For antioxidant activity, the results showed hot-air drying at 70°C effected highest TPC similar to freeze drying.


2018 ◽  
Vol 12 (3) ◽  
pp. 2145-2157 ◽  
Author(s):  
Begoña de Ancos ◽  
Concepción Sánchez-Moreno ◽  
Lorenzo Zacarías ◽  
María Jesús Rodrigo ◽  
Sonia Sáyago Ayerdí ◽  
...  

2018 ◽  
Vol 192 ◽  
pp. 03001
Author(s):  
Thitiphan Chimsook

This study determined the effect of drying methods including hot air drying and freeze drying on the quality of cordycepin production from Cordyceps militaris. The fruiting bodies and mycelium of C. militaris were used as the raw material. For hot air drying was performed at 55 °C for 24 hrs. Whereas the freeze drying was carried out under vacuum at 140 L min-1 for 48 hours. The bioactive compound extracted from dried powder of C. militaris from two drying methods was investigated. The results showed that both cordycepin and adenosine extracted from freezed drying sample had higher value than those of extracted from hot air dried sample. The bioactivities of C. militaris extract were investigated. The results revealed that the antioxidant activity and also total phenolic contents of C. militaris extract prepared from freeze drying had higher value than that of extracted from hot air drying. However, most of C. militaris production performed using hot air drying to dry sample because of its low cost technique.


Author(s):  
Esteban I Mejia-Meza ◽  
Jaime A. Yanez ◽  
Neal M. Davies ◽  
Barbara Rasco ◽  
Frank Younce ◽  
...  

Blueberries (Vaccinium corymbosum L.) were dried combining microwave-vacuum, hot-air drying and freeze drying technologies to retain their nutritional value. Polyphenol retention, total polyphenols, anthocyanins, and antioxidant activity were evaluated in dried blueberries. Glycoside compounds for ellagic acid, quercetin, and kaempferol exhibited a higher retention than phloridzin, and R- and S-naringin in dried blueberries following dehydration. Freeze and HA-MIVAC® dried blueberries had a higher retention of total polyphenols and anthocyanins. Freeze dried blueberries had higher antioxidant activity, followed by the combination of HA-MIVAC®, MIVAC® and HA drying methods. FD, HA-MIVAC® and MIVAC® treated blueberries had a higher retention of individual polyphenols than HA treated blueberries, indicating that the nutritional properties of berries may be retained to a greater extent when these processes are employed.


Foods ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 868
Author(s):  
Junjie Xia ◽  
Zili Guo ◽  
Sheng Fang ◽  
Jinping Gu ◽  
Xianrui Liang

Burdock (Arctium lappa L.) is one of the nutritional foods widely planted in many countries. Dried burdock root (BR) is available as a herbal tincture and tea in many Asian countries with good flavor and taste. In this study, the volatile components in dried BR were identified and the effects of different drying methods on the volatile components were investigated by HS-GC-MS method. A total of 49 compounds were identified. Different drying methods including hot-air drying (HD, at 50, 60, 70, and 80 °C), vacuum drying (VD, at 50, 60, 70, and 80 °C), sunlight drying (SD), natural drying (ND), and vacuum freeze drying (VFD) were evaluated by HS-GC-MS-based metabolomics method. Results showed that different drying methods produced different effects on the volatile compounds. It was observed that 2,3-pentanedione, 1-(1H-pyrrol-2-yl)-ethanone, furfural, and heptanal were detected at higher concentrations in HD 80 and VD 70. The traditional HD and SD methods produced more flavor substances than VFD. The BR treated by the VFD method could maintain the shape of the fresh BR pieces while HD50 and VD80 methods could maintain the color of fresh BR pieces. These findings could help better understand the flavor of the corresponding processed BR and provide a guide for the drying and processing of BR tea.


2014 ◽  
Vol 10 (2) ◽  
pp. 251-260 ◽  
Author(s):  
Kianoosh Pirnazari ◽  
Ali Esehaghbeygi ◽  
Morteza Sadeghi

Abstract In the present study, banana slices were dried and compared using electrohydrodynamic (EHD) drying method at 4.5, 6.5, and 8.5 kV/cm; oven at 50, 60, and 70°C; and hot-air drying at 50, 60, and 70°C at a constant air velocity of 1.5 m/s. ANOVA showed that drying method had a significant effect on drying time, rehydration capacity, shrinkage, color features (L*, a*, b*, and ∆E), and consumed energy. The values of consuming energy for EHD at 8.5 kV/cm, oven, and hot-air drying at 70°C were 2.99, 20.9, and 81.7 kJ/g run on full capacity of each dryer, respectively. Oven drying led to a greater color change than did hot-air. No significant difference was observed between the color change feature ∆E for EHD and hot-air dried samples in the orthogonal contrast analysis. The falling rate period for EHD moisture movement showed that diffusion was describing the moisture gradients and the internal moisture transfer was dominant. EHD is not fast; however, its advantages like less energy needed, lower shrinkage, and great rehydration capacity make it a good choice for combining with other convection drying methods.


2021 ◽  
Vol 10 (4) ◽  
pp. 3110-3114
Author(s):  
Madhumita Saha

The objective of this study was to analyse the effects of phytochemical parameter, physical parameter, color, and sensory analysis in green capsicum by different drying processes (microwave, freeze, and hot air drying). Results showed an increase in microwave output power (600W), decreased drying time, moisture content, Chroma, and bulk density values. The Freeze drying process significantly improved the lightness of dried capsicum. Due to take less time for the Microwave drying technique, phytochemical parameters are intact in capsicum; on the other side, color degradation has been occurred due to the Maillard reaction (L*=29.34±0.08, a*=6.98±0.09,b*=15.36±0.10). Bulk density (0.335±0.01) and dispersibility (40±2.00%) were highest in Microwave drying powder. The capsaicin content of dried capsicum was higher than the fresh capsicum sample, but compared to the different drying techniques, the Microwave drying sample has higher capsaicin content than the Hot air drying and Freeze-drying samples. The lower capsaicin content in fresh capsicum may occur due to the catalytic activity of the peroxidase enzyme. The capsaicin content of all dried capsicum varied between 1.91±0.05 and 3.31±0.16 mg/100 g. In this research, the Microwave drying powder of capsicum was the best product for its highest antioxidant content and other physical properties.


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