scholarly journals Variation law and prediction model to determine the moisture content in tea during hot air drying

Author(s):  
Dongyao Duan ◽  
Fangyan Ma ◽  
Liqing Zhao ◽  
Yuanyuan Yin ◽  
Yinghui Zheng ◽  
...  
2021 ◽  
Vol 17 (9) ◽  
pp. 727-735
Author(s):  
Jiamei Long ◽  
Jia Yang ◽  
Jing Peng ◽  
Leiqing Pan ◽  
Kang Tu

Abstract Moisture content and carotenoid content are important indicators for evaluating the drying process of carrot slices. There are growing attention to develop non-destructive methods as effectively analytical tools in quality assurance of drying carrot slices. In this study, the characteristic wavelengths of moisture and carotenoid content in carrot slices during hot air drying were extracted based on hyperspectral imaging technology. A multispectral imaging equipment was built after that, and the wavelengths of filters were determined according to the characteristic wavelengths. Based on the successive projection algorithm (SPA), the optimal wavelengths of moisture and carotenoid content were further determined, and prediction models of both were established based on the system. There were 12 filters selected in this study. The results showed that a support vector machine (SVM) prediction model for moisture content was established based on seven optimal wavelengths with 0.991 for the coefficient of determination of prediction set (R 2 p ) and 10.318 for the residual prediction residual (RPD). Based on eight optimal wavelengths, a SVM prediction model for carotenoid content was also established with 0.968 for R 2 p and 5.337 for RPD. The prediction performance is close to or even better than that based on hyperspectral. The study confirmed the feasibility of using the multispectral imaging equipment to measure the moisture and carotenoid content of carrot slices during drying based on selected wavelengths, laying a foundation for the further preparation of a portable multispectral detector for the quality of dry products.


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.


2008 ◽  
Author(s):  
Takahiro Orikasa ◽  
Daisuke Nei ◽  
Poritosh Roy ◽  
Nobutaka Nakamura ◽  
Takeo Shiina ◽  
...  

Foods ◽  
2020 ◽  
Vol 9 (1) ◽  
pp. 101 ◽  
Author(s):  
Senadeera ◽  
Adiletta ◽  
Önal ◽  
Di Matteo ◽  
Russo

Drying characteristics of persimmon, cv. “Rojo Brillante”, slabs were experimentally determined in a hot air convective drier at drying temperatures of 45, 50, 55, 60, and 65 °C at a fixed air velocity of 2.3 m/s. It was observed that the drying temperature affected the drying time, shrinkage, and colour. Four empirical mathematical models namely, Enderson and Pabis, Page, Logarithmic, and Two term, were evaluated in order to deeply understand the drying process (moisture ratio). The Page model described the best representation of the experimental drying data at all investigated temperatures (45, 50, 55, 60, 65 °C). According to the evaluation of the shrinkage models, the Quadratic model provided the best representation of the volumetric shrinkage of persimmons as a function of moisture content. Overall, higher drying temperature (65 °C) improved the colour retention of dried persimmon slabs.


2013 ◽  
Vol 395-396 ◽  
pp. 571-576
Author(s):  
Xue Bi Zhang ◽  
Si Yu Chen ◽  
Wen Fu Wu ◽  
Ya Qiu Zhang ◽  
Chun Shan Liu ◽  
...  

In order to reduce the damage rate of hot-pepper in the process of drying and transportation, and to improve the quality of dried hot-pepper. In this paper, the mechanical properties of hot-pepper were studied in the process of hot-air drying. The experimental results showed that the hot-pepper’s compressive ability dropped with the decrease of moisture content after the moisture content reached the safe moisture content. With the moisture content decreasing, the variation tendency of the elastic modulus and tensile strain of hot-pepper were first increased and then decreased and finally tended to be stable when it reached 12%. Effect of hot-pepper’s shape on tensile strain is greater than on the maximum load and displacement in the process of drying.


2012 ◽  
Vol 622-623 ◽  
pp. 69-74
Author(s):  
T. Ninchuewong ◽  
S. Tirawanichakul ◽  
Y. Tirawanichakul

The objective of this research was to predict drying behavior of hot air drying using an empirical model (EM) and an artificial neural network model (ANN). Rubber sheet with initial moisture content ranging of 23-40% dry-basis was dried by temperature ranging of 40-70°C and air flow rate of 0.7 m/s. The desired final moisture content was set at 0.15% dry-basis. The results showed that drying rate of rubber sheet dried with hot air convection was faster than conventional natural aeration. The EM and ANN were simulated to describe the drying behavior of products. Furthermore, prediction results between EM and ANN were compared with the experimental data. In this research, it was obviously found that ANN can describe the drying behavior effectively. Additionally, it was also found that predicted results of Multilayer feed forward Levenberg-Maqurdt’s Back-propagation ANN were good agreement with the experimental results compared to those results of EM. It is the optimum architecture for prediction the evolution of moisture transfer for hot air drying.


Author(s):  
Xiaoli Huang ◽  
T. Li ◽  
S.N. Li ◽  
Z.H. Wu ◽  
J. Xue

In this paper, hot air drying (HAD) was applied when moisture content of apple slices range from 50% to 86%, and then vacuum-filling nitrogen drying (VFND) was used till moisture content reaching 7%. Results showed that, the drying rate of apple slice during VFND period increased with temperature increment and decreased with increment of slice thickness; compared to freezing dried samples,  samples dried in this research were owned lower Vc and higher flavonoid; when HAD (70℃,3.0m/s)+VFND(relative pressure 0.08MPa, 50℃) and thickness of 6.0mm, nutrients reached better levels: retentions of Vc, total phenolics and flavonoid were 1.63mg/100g, 4.07mg/100g and 2.10mg/100g, respectively. Keywords: apple slices, hot air drying, vacuum-filling nitrogen drying, drying rate, nutrients


2010 ◽  
Vol 16 (4) ◽  
pp. 337-341 ◽  
Author(s):  
A. Frías ◽  
G. Clemente ◽  
A. Mulet

Shrinkage is one of the most important physical changes that occur during the dehydration of foods. In this work, the effect of the temperature (35, 40, 50, 60 and 70 °C) and air velocity (7, 8, 9 and 10 m/s) on bulk volumetric shrinkage was investigated. Volume changes were evaluated by image analysis. It was found that neither temperature nor air velocity had any significant effects on bulk shrinkage in this system. The bulk shrinkage of the potato cubes was well correlated with the moisture content of the sample during drying (R2 = 97.28). Volume varied linearly with the moisture content changes under the studied conditions. The volume of lost water and the decrease in volume of the samples during dehydration were similar.


Author(s):  
Luna Shrestha ◽  
Roberto Moscetti ◽  
Stuart Crichton ◽  
Oliver Hensel ◽  
Barbara Sturm

Organic dried apples are common snacks fulfilling functional as well as nutritional aspects. However, appearance of dried slices does not always satisfy consumer requirements, thus, improvements are needed. In this study, partial least squares (PLS) regression models were successfully developed to monitor changes in colour and moisture content in apple slices during the drying process over the Vis/NIR spectral range. The regression vector analysis results suggested that features at 580, 750 and 970 nm are better for predicting moisture content, while 580 and 680 nm allow to measure the (a*/b*) colour ratio.   Keywords: Drying; Dried apple slices; Moisture content; Colour; PLSR modelling


Sign in / Sign up

Export Citation Format

Share Document