Effects of different drying methods of cauliflower waste on drying time, colour retention and glucoamylase production by Aspergillus niger NCIM 1054

In this study, the impacts of two different pear cultivars, “Conference” and “Alexander Lucas”, on the kinetics and the final quality of samples dried by convection (CD) and microwave-convection (MCD) methods, were investigated. The quality of dried material was evaluated by the analysis of water activity, porosity, color, acoustic emission (AE) and mechanical and sensory properties. The required drying time to obtain 0.2 kg H2O/kg dry solid (d.s.) was longer for “Conference” than “Alexander Lucas” and was 20 min by CD and 5 min by MCD. The pear cultivar, in conjunction with the drying method (CD or MCD), affected the number of AE events and the work of breaking. The CD pear of the “Conference” cultivar was characterized by higher force, higher breaking work and stronger AE relative to the CD pear of the “Alexander Lucas” cultivar. There were no differences in taste or overall quality, but the hardness was higher for the CD “Conference” pear. A principal component analysis showed that panelists preferred dried fruit with good taste and overall quality but lower hardness. A positive correlation was found between the number of acoustic events and sensory hardness; thus, an acoustic method can be useful for effectively evaluating the texture of dried pears. These results show that the dried pear slices that generated fewer AE events upon breaking were perceived as better by the panelists.

Download Full-text

Effects of Blanching and Natural Convection Solar Drying on Quality Characteristics of Red Pepper (Capsicum annuum L.)

International Journal of Food Science ◽

10.1155/2017/4656814 ◽

2017 ◽

Vol 2017 ◽

pp. 1-6 ◽

Cited By ~ 1

Author(s):

James Owusu-Kwarteng ◽

Francis K. K. Kori ◽

Fortune Akabanda

Keyword(s):

Natural Convection ◽

Quality Characteristics ◽

Red Pepper ◽

Plain Water ◽

Drying Methods ◽

Solar Drying ◽

Drying Time ◽

Sun Drying ◽

Overall Acceptability ◽

Solar Dryer

The objective of this work was to determine the effects of blanching and two drying methods, open-sun drying and natural convection solar drying, on the quality characteristics of red pepper. A 2 × 3 factorial design with experimental factors as 2 drying methods (open-sun drying and use of solar dryer) and 3 levels of pepper blanching (unblanched, blanched in plain water, and blanched in 2% NaCl) was conducted. Dried pepper samples were analysed for chemical composition, microbial load, and consumer sensory acceptability. Blanching of pepper in 2% NaCl solution followed by drying in a natural convection solar dryer reduced drying time by 15 hours. Similarly, a combination of blanching and drying in the solar dryer improved microbial quality of dried pepper. However, blanching and drying processes resulted in reduction in nutrients such as vitamin C and minerals content of pepper. Blanching followed by drying in natural convection solar dryer had the highest consumer acceptability scores for colour and overall acceptability, while texture and aroma were not significantly (p>0.05) affected by the different treatments. Therefore, natural convection solar dryer can be used to dry pepper with acceptable microbial and sensory qualities, as an alternative to open-sun drying.

Download Full-text

Comparative Study of Hot Air Drying and Microwave Drying for Dewatered Sludge

10.21203/rs.3.rs-178542/v1 ◽

2021 ◽

Author(s):

Wittawat Wulyapash ◽

Awassada Phongphiphat ◽

Sirintornthep Towprayoon

Keyword(s):

Microwave Power ◽

Specific Energy Consumption ◽

Microwave Drying ◽

Drying Methods ◽

Drying Time ◽

Hot Air ◽

Air Temperatures ◽

Dewatered Sludge ◽

Dried Sludge ◽

Seafood Processing

Abstract Large amounts of sludge are generated from wastewater treatment in seafood processing industries. Most of the dewatered sludge in Thailand is not utilized and disposed by landfilling. The dried sludge utilization as refuse-derived fuel (RDF) is an alternative solution due to the gross calorific value (GCV), which is greater than 21.9 MJ/kg. However, the key obstacle is its high moisture content of 87.4% (wet basis). Therefore, drying methods using hot air and microwave techniques were investigated for preparing dried sludge. The effects of hot air temperatures (100-150 °C) and microwave power levels (100-800 W) were compared on drying kinetics, specific energy consumption (SEC), and characteristics of the dried products. The results showed that drying times were decreased by increasing the hot air temperatures. In the same way, the increase in microwave power levels decreased the drying time. The application of microwaves contributed to reducing the drying time by more than 46% compared to the hot air. The reduction of drying times resulted in the saving SEC. The GCV of the dried sludge decreased with the decrease in the volatile matter (VM) due to the high component of VM as 79.5-80.3% (dry ash-free basis). The sludge dried by the microwaves showed a lower GCV than the hot air products. However, dried sludges still had high GCV (≥ 20.8 MJ/kg). Furthermore, the minimal variation of the product characteristics demonstrated that the microwave technique could be applied as an alternative drying method with a rapid process compared to the conventional hot air technique.

Download Full-text

Thin-layer mathematical modeling of apple slices drying, using open sun and cabinet solar drying methods

International Journal of Innovative Research and Scientific Studies ◽

10.53894/ijirss.v4i2.55 ◽

2021 ◽

Vol 4 (2) ◽

pp. 43-52

Author(s):

Abdul Wasim Noori ◽

Mohammad Jafar Royen ◽

Juma Haydary

Keyword(s):

Thin Layer ◽

Mathematical Models ◽

Water Activity ◽

Model Fitting ◽

Coefficient Of Determination ◽

Drying Methods ◽

Solar Drying ◽

Drying Time ◽

Climate Conditions ◽

Thin Layer Drying

This paper aims to investigate the effect of climate conditions such as ambient temperature, humidity, pressure, sun radiation and pollution on sliced apples quality and drying time which are dried in an indirect forced cabinet solar drying (IFCSD) and open sun drying (OSD) systems. Both experiments were implemented at same place (Kabul, Afghanistan) and time. The IFCSD yield for saving time is 42.8 % which is more effective than drying in the OSD system. Simultaneously with the decreasing of sliced apple weight from 512.9 g down to 73.9 g, the water activity decreased from 0.955 down to 0.355 in the IFCSD system. For OSD system, the sample weight decreased from 512.6 g down to 78.4 g and its water activity from 0.955 down to 0.411. On the experiment day the average sun radiation was 571 w/m2 . The pressure drop between inlet and outlet of the dryer was 0.1 kPa. Different thin-layer mathematical models were investigated to identify the best model fitting the experimental data. The mathematical models’ performances were investigated by comparing the coefficient of determination (R 2 ), reduced chi-square (X2 ) and root mean square error (RMSE) coefficients. From all 11 applied thin-layer drying models the Page, Approximation diffusion, Verma et al and Midilli and Kacuk models are more fitted to our data.

Download Full-text

Effects of drying methods on color retention and chlorophyll of celery (ApiumgraveolensL.), spinach (Spinacia oleraceaL.), Malabar spinach (Basella albaL.)

The Journal of Agriculture and Development ◽

10.52997/jad.6.06.2020 ◽

2020 ◽

pp. 53-61

Author(s):

Dat Q Tran

Keyword(s):

Microwave Drying ◽

Drying Methods ◽

Hot Air Drying ◽

Drying Time ◽

Air Drying ◽

Color Retention ◽

Hot Air ◽

Drying Techniques ◽

Dried Vegetables

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

Download Full-text

Physicochemical Properties of Dried Apple Slices: Impact of Osmo-Dehydration, Sonication, and Drying Methods

Molecules ◽

10.3390/molecules25051078 ◽

2020 ◽

Vol 25 (5) ◽

pp. 1078

Author(s):

Joanna Cichowska-Bogusz ◽

Adam Figiel ◽

Angel Antonio Carbonell-Barrachina ◽

Marta Pasławska ◽

Dorota Witrowa-Rajchert

Keyword(s):

Physicochemical Properties ◽

Osmotic Dehydration ◽

Convective Drying ◽

Drying Methods ◽

Drying Method ◽

Drying Time ◽

Hygroscopic Properties ◽

Fruit Samples ◽

Apple Slices ◽

Pre Treatment

Apple slices of the Elise variety were previously osmo-dehydrated in erythritol, xylitol, and sucrose for 2 h. In some parts of the experiment, 30 min of ultrasound pre-treatment (US) were applied. Afterwards, fruit samples were dried by convective (CD), microwave-vacuum (VM), and a combined method (CD/VM, mix two of them). The main aim of the research was to characterize an impact of osmotic dehydration, sonication pre-treatment, and drying method on the physicochemical properties of the dried apples. The use of sugar alcohols (xylitol, erythritol) in the production of dried apples did not badly affect the taste of the obtained dried products; it enabled a noticeable cooling/refreshing effect felt in the mouth when consuming a snack, and enabled the production of dried snacks with lower calorific value. Polyol residues in the product were at a level that was safe for consumers. The most popular convective drying was long lasting, whereas the VM drying method allowed for the shortest drying time, amounting to 76 min; moreover, additional application of ultrasounds reduced this time to 36 min. The combined drying method allowed the total duration of the process to be reduced 2–4.5 times. Ultrasound applied during osmotic dehydration did not significantly affect attributes of the descriptive sensory analysis for the obtained dried apples. The best hygroscopic properties, ensuring the storage stability of the dried product, showed dried apples previously osmo-dehydrated in erythritol and sucrose solutions.

Download Full-text