Selected physical and viscoelastic properties of strawberries as a function of heated-air drying conditions

2019 ◽  
Vol 37 (14) ◽  
pp. 1833-1843 ◽  
Author(s):  
Oguz Kaan Ozturk ◽  
Pawan Singh Takhar
2014 ◽  
Vol 77 (3) ◽  
pp. 466-471 ◽  
Author(s):  
HYE JIN CHOI ◽  
TAE-JIN AN ◽  
JUIL KIM ◽  
SEONG-HWAN PARK ◽  
DONGWOOK KIM ◽  
...  

Improperly practiced postharvest procedures can pose mycotoxin-related risks in the production of medicinal herbs. As a health food with pharmacological supplements, cereal-based adlay has been broadly used in oriental medical practice. Compared with the standard production protocol, three provisional critical control points (CCPs) in the conventional procedure were identified and assessed for mycotoxin contamination in the adlay from small farms in Korea. Although various mycotoxins were present, the prevalence of deoxynivalenol (DON) or zearalenone (ZEN) was relatively high in the adlay. In terms of drying conditions, field drying in the conventional pathway was associated with more exposure to DON than heated-air drying. Moreover, the DON or ZEN levels in chaff were higher than the levels in the inner grain, suggesting that the hulling process as another CCP would reduce the DON or ZEN exposure. In particular, the DON or ZEN levels in adlay stored for protracted periods without dehulling were very high, but a lower storage temperature of 12°C was not effective at significantly reducing these mycotoxins. In this case, the inner grain was more contaminated with DON or ZEN than the chaff after protracted storage because surface fungi, which produce mycotoxins, can penetrate deep into grain with time. Heated-air drying and nonprotracted storage limited DON contamination in adlay. More importantly, an early dehulling process should be adopted as an easy preventive action to reduce the risk of exposure to DON or ZEN in adlay postharvest. This is monitored as a central CCP for safer production of adlay from local farms.


2011 ◽  
Vol 36 (2) ◽  
pp. 109-115 ◽  
Author(s):  
Tae-Hwann Kang ◽  
Hyun-Gi Hong ◽  
Hong-Young Jeon ◽  
Chung-Su Han

1975 ◽  
Vol 18 (5) ◽  
pp. 0942-0945 ◽  
Author(s):  
D. G. Overhults ◽  
G. M. White ◽  
H. E. Hamilton ◽  
I. J. Ross ◽  
J. D. Fox

Author(s):  
Krishna Guntur ◽  
R. S. Amano ◽  
Brinda Athreya

Paper mills use elaborated drying process using hot rollers to dry the paper. In the recent past, use of hot air for drying has gained some interest. The main disadvantage of this method is non-uniform air temperature, which will cause lateral shrinkage of the paper. This paper discusses a new drying system. The process incorporates a porous medium to ensure uniform temperature by flattening the velocity distribution. The new system requires less equipment pieces and utilized less space for the drying process. A cloth is used in place of paper to increase the repeatability of the experiment. This experiment utilized a conveyor system to transport the cloth within the heater section. Variables concerning velocity and temperature values of the heated air, and heater intensity were adjusted to produce the different drying conditions. Forced air propane heater was used as the heat source. Design modifications were made so that the heater is more suitable for this process. The results showed significant improvement of the velocity and feasibility of extending this technology to the actual scale.


2019 ◽  
Vol 50 (3) ◽  
pp. 150-158 ◽  
Author(s):  
Nnaemeka R. Nwakuba

High-energy demand of convective crop dryers has prompted study on optimisation of dryer energy consumption for optimal and cost effective drying operation. This paper presents response surface optimisation of energy consumption of a solar-electric dryer during hot air drying of tomato slices. Drying experiments were conducted with 1 kg batch of tomato samples using a 33 central composite design of Design Expert 7.0 Statistical Package. Three levels of air velocity (1.0, 1.5 and 2.0 ms–1), slice thickness (10, 15 and 20 mm) and air temperature (50, 60 and 70°C) were used to investigate their effects on energy consumption. A quadratic model was obtained with a high coefficient of determination (R2) of 0.9825. The model was validated using the statistical analysis of the experimental parameters and normal probability plot of the energy consumption residuals. Results obtained indicate that the process parameters had significant quadratic effects (P<0.05) on the energy consumption. The energy consumption varied between 5.42 kWh and 99.78 kWh; whereas the specific energy consumption varied between 5.53 kWhkg–1 and 150.61 kWhkg–1. The desirability index method was applied in predicting the ideal energy consumption and drying conditions for tomato slices in a solar-electric dryer. At optimum drying conditions of 1.94 ms–1 air velocity, 10.36 mm slice thickness and 68.4°C drying air temperature, the corresponding energy consumption was 5.6 8kWh for maximum desirability index of 0.989. Thermal utilisation efficiency (TUE) of the sliced tomato samples ranged between 15 ≤TUE ≤58%. The maximum TUE value was obtained at 70°C air temperature, 1.0 ms–1 air velocity and 10 mm slice thickness treatment combination, whereas the minimum TUE was obtained at 50°C air temperature, 2.0 ms–1 air velocity and 20 mm slice thickness. Recommendation and prospect for further improvement of the dryer system were stated.


2018 ◽  
Vol 52 (4) ◽  
pp. 121-128 ◽  
Author(s):  
Dae-Bin Song ◽  
◽  
Ki-Hyeon Lim ◽  
Dae-Hong Jung

Author(s):  
MILAD ASGARPOUR KHANSARY ◽  
FARZANEH KAZEMI QALEH JOOGH ◽  
ASHKAN HOSSEINI ◽  
JABER SAFARI ◽  
EDRIS ALLAHYARI ◽  
...  

Drying of a coated paper is modeled and simulated. The paper sheet is assumed to form three zones, and each zone has its own drying mechanism. Coupling of energy and mass balances must be used in order to solve differential equations. The simulations are carried out in various drying conditions i.e., only hot air drying, only radiant drying, and mixed hot air-radiant drying. Also the effect of one side and two side assumption on evaporation is studied. Effect of venting air speed and radiant heat source presence and its distance from the drying surface on the drying of a coated paper has been studied. It is found that both distance and venting air speed are inversely related to drying in mixed hot air-radiant drying. Both surfaces participate in evaporation however, during the last time of drying, no difference between the upper and the bottom surfaces exist.


2020 ◽  
Vol 51 (4) ◽  
pp. 200-208
Author(s):  
Ernest Ekow Abano ◽  
Robert Sarpong Amoah ◽  
Catherine Mbabazi

The objective of this work was to identify the optimal drying conditions to produce better quality dried Moringa oleifera leaves with the best drying kinetics using microwave and steam blanching pre-treatments prior to hot air drying. For this purpose, the effect of microwave power, microwave time, steaming time, and air temperature on drying kinetics and quality of Moringa leaves was evaluated using the response surface methodology. In order to achieve a moisture content of 8.0% kg H2O/kg dry matter, the optimal conditions identified were a steaming time of 2.58 min (2 min 35 sec) prior to air drying at 70°C and a microwave power of 270 W for 3 min, followed by air drying at 70°C. At this optimal condition, a confirmation test for steam-assisted air drying gave a drying time (DT) of 53 min, ascorbic acid (AA) of 2.49 mg/g, and the antioxidant activity (AOA) of 67.244% inhibition. For microwave-assisted air drying, the confirmation experiment gave a DT of 43 min, AA of 2.699 mg/g, and AOA of 74.46% inhibition. Both pre-treatments before air drying followed a falling rate drying period at the initial stages and later a constant rate drying period. Our results showed that microwave blanching should be considered as a pre-treatment in industrial production of Moringa leaves to produce better quality dried products in a relatively short time.


2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Hui Xie ◽  
Wen Zhang ◽  
Shouan Han ◽  
Min Wang ◽  
Liuwei Qin ◽  
...  

Abstract The commercial value of green raisins produced by the shade-air drying in Liang-fang was 2–3 times as high as that of yellow-brown raisins. This study systematically evaluated the effect of the temperature, humidity, and light of sun drying and shade-air drying on raisins. The sugar, acids, texture and color parament of raisins were compared with different drying conditions. The results indicated that shade-air drying can offer a dark and conducive light environment with the maximum temperature below 40 °C, and a lower humidity by segregating rainwater during the day as well. Then, the contents of acids of raisins in sun drying were lower compared with the shade-air drying and had a lower hardness and a* values of raisins. In summary, low light and ultraviolet intensity, suitable temperature and appropriate humidity environments were the basal and key factors for the formation of the green raisins. The present study not only revealed the crucial factors during shade-air drying in Liang-fang in Turpan, but also provided a scientific basis for improving the Liang-fang conditions and producing green raisins in other regions.


Author(s):  
Nnaemeka R. Nwakuba

High-energy demand of convective crop dryers has prompted study on optimization of dryer energy consumption for optimal and cost effective drying operation. This paper presents response surface optimization of energy consumption of a solar-electric dryer during hot air drying of tomato slices. Drying experiments were conducted with 1kg batch of tomato samples using a 33Central Composite Design (CCD) of Design Expert 7.0 Statistical Package. Three levels of air velocity (1.0, 1.5 and 2.0ms–1), slice thickness (10, 15 and 20mm) and air temperature (50, 60 and 70oC) were used to investigate their effects on energy consumption. A quadratic model was obtained with a high coefficient of determination (R2) of 0.9825. The model was validated using the statistical analysis of the experimental parameters and normal probability plot of the energy consumption residuals. Results obtained indicate that the process parameters had significant quadratic effects (p < 0.05) on the energy consumption. The energy consumption varied between 5.42kWh and 99.78kWh; whereas the specific energy consumption varied between 5.53kWhkg–1and 150.61kWhkg–1. The desirability index method was applied in predicting the ideal energy consumption and drying conditions for tomato slices in a solar-electric dryer. At optimum drying conditions of 1.94ms–1air velocity, 10.36mm slice thickness and 68.4oC drying air temperature, the corresponding energy consumption was 5.68kWh for maximum desirability index of 0.989. Thermal utilization efficiency (TUE) of the sliced tomato samples ranged between 15 ≤ TUE ≤ 58%. The maximum TUE value was obtained at 70oC air temperature, 1.0ms–1air velocity and 10mm slice thickness treatment combination, whereas the minimum TUE was obtained at 50oC air temperature, 2.0ms–1air velocity and 20mm slice thickness. Recommendation and prospect for further improvement of the dryer system were stated.


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