Hot air drying of purple-speckled Cocoyam (Colocasia esculenta (L.) Schott) slices: Optimisation of drying conditions for improved product quality and energy savings

Ndisya, John; Mbuge, Duncan Onyango; Kulig, Boris; Gitau, Ayub Njoroge; Hensel, Oliver; Sturm, Barbara

doi:10.1016/j.tsep.2020.100557

Cited by 26 publications

(43 citation statements)

References 41 publications

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“…Lower energy consumption for higher temperatures is due to the decrease in drying time that compensates for the energy demand. These results are in agreement with the investigation performed by Koyuncu et al (2007) and Ndisya et al (2020) wherein the temperature was observed to have a significant effect on the specific energy consumption as an increase in temperature compensates for the corresponding drying time and in turn the high energy demand. Overall, the P strategy had the overall lowest energy consumption.…”

Section: Energy Consumptionsupporting

confidence: 92%

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Investigating the Effect of Different Drying Strategies on the Quality Parameters of Daucus carota L. Using Dynamic Process Control and Measurement Techniques

Raut

Saleh

Kirchhofer

et al. 2021

Food Bioprocess Technol

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The present work aims to improve the understanding of the effect of different drying strategies at varying temperatures on the dynamic drying behaviour and quality of organic products such as carrots using non-invasive measurement techniques. For this purpose, carrot slices of 3 mm thickness were dried under three different strategies namely air temperature controlled (A), product temperature controlled (P) and stepwise temperature controlled (S) at different temperatures (50 °C, 60 °C and 70 °C) to measure and analyse the changes in moisture content, colour, total carotenoid retention, water activity, rehydration ratio and specific energy consumption. From the investigation performed, it was incurred that the application of different drying strategies influences rather significantly both the product quality as well as the overall process efficiency. Modelling the drying curves deemed Page model to be a good fit for all the strategies with R2adj = 0.99 and RMSE = 0.01. The results also show that implementing strategy P not only led to shorter drying times but also led to higher total carotenoid retention within the samples (TCR = 0.59–0.73). Colour changes, however, were observed to be maximum with strategy P as compared to strategy A and strategy S. Furthermore, the use of a non-invasive measurement technique such as infrared camera proved to be reliable in order to detect the phase transition of the product during the drying process.

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Section: Energy Consumptionsupporting

confidence: 92%

“…Calculation of the mass specific energy demand of the product was conducted using Eqs. 14-19 (Aghbashlo et al, 2008;Motevali et al, 2011;Ndisya et al, 2020):…”

Section: Energy Calculationmentioning

confidence: 99%

Investigating the Effect of Different Drying Strategies on the Quality Parameters of Daucus carota L. Using Dynamic Process Control and Measurement Techniques

Raut

Saleh

Kirchhofer

et al. 2021

Food Bioprocess Technol

Self Cite

View full text Add to dashboard Cite

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“…Furthermore, increasing velocity also increases the overall energy demand for the drying process [9]. Changing the drying temperature, the overall drying time is observed to have reduced from 210 min for 60 • C to 180 min for 65 • C. This is analogous to the several investigations performed on the influence of drying temperature on the drying time [20,23,[28][29][30]. From the drying curve presented in Figure 6b, it is also observed that the moisture losses were rapid for 60 • C than 65 • C for the initial phase (up to 60 min), indicating that the 60 • C bulk dried faster than the 65 • C bulk.…”

Section: Drying Behaviorsupporting

confidence: 54%

“…where DM i is the amount of dry matter per kg, MC f is the final moisture content, DM f is the amount of dry matter in the bulk (kg) and W i is the initial weight of bulk. The specific energy requirement per bulk weight was calculated using Equations ( 14) and ( 15) [22,23]:…”

Section: Energy Consumptionmentioning

confidence: 99%

Impact of Process Parameters and Bulk Properties on Quality of Dried Hops

et al. 2020

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Hops are critical to the brewing industry. In commercial hop drying, a large bulk of hops is dried in multistage kilns for several hours. This affects the drying behavior and alters the amount and chemical composition of the hop oils. To understand these changes, hops of the var. Hallertauer Tradition were dried in bulks of 15, 25 and 35 kg/m² at 60 °C and 0.35 m/s. Additionally, bulks of 25 kg/m² were also dried at 65 °C and 0.45 m/s to assess the effect of change in temperature and velocity, respectively. The results obtained show that bulk weights significantly influence the drying behavior. Classification based on the cone size reveals 45.4% medium cones, 41.2% small cones and 8.6% large cones. The highest ΔE value of 6.3 and specific energy consumption (113,476 kJ/kgH2O) were observed for the 15 kg/m² bulk. Increasing the temperature from 60 °C to 65 °C increased the oil yield losses by about 7% and myrcene losses by 22%. The results obtained show that it is important to define and consider optimum bulk and process parameters, to optimize the hop drying process to improve the process efficiency as well the product quality.

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“…To quantify MC, the samples were dried at 105°C in hot‐air oven under atmospheric pressure until reaching a constant weight. MC was determined by using Equation 2 (Ndisya et al., 2020):

MC = \frac{W_{normali} ‐ W_{normalf}}{W_{i}}

…”

Section: Methodsmentioning

confidence: 99%

Quantitative analysis and visualization of moisture and anthocyanins content in purple sweet potato by Vis–NIR hyperspectral imaging

Tian

Aheto

Bai

et al. 2020

J. Food Process. Preserv.

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Total anthocyanin (TA) and moisture content (MC) are critical indexes of processed purple sweet potatoes (PSPs). The current study examined the feasibility of hyperspectral imaging to investigate how MC and TA contents of PSPs change during processing under two different drying methods namely convective hot‐air drying (CHD) and microwave drying (MD). Models based on spectral data and the integration of spectral and one or three gray‐level co‐occurrence matrix features were established with partial least square regression. The best prediction outcome based on Spectra + HOMOGENEITY + CONTRAST + ENTROPY combinations were (Rp2 = 0.862, 0.847; RMSEP = 0.079, 0.303), respectively, for MC and TA for the CHD samples. Similarly, for the MD samples, the best prediction outcomes were (Rp2 = 0.867, 0.859; RMSEP = 0.088, 0.241), respectively, for MC and TA. Image algorithms were also developed to generate distribution of MC and TA in some representative samples. Practical applications Anthocyanins have been reported as having the potential to lower blood pressure, improve eyesight, reduce cancer cell multiplication, impede tumor formation, and prevent diabetes. Studies have, however, shown that cooking modes including boiling, baking, and steaming decreased the contents of anthocyanins. This study assessed the impact of convective hot‐air and microwave drying (MD) process of purple sweet potato (PSP) on total anthocyanin (TA) content as a function of moisture loss. Hyperspectral Imaging (HSI) was useful in estimating not only the contents of TA and moisture, but also in generating a visual map of their distribution pattern in the processed PSPs. The TA content of PSPs processed by MD was higher than that by convective hot‐air drying, but the distribution uniformity of TA in microwave dried PSPs was worse than that in convective hot‐air dried samples. Finally, to guarantee consistency in drying processes of food products, the HSI could be used to obtain visual images of their chemical parameters.

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Hot air drying of purple-speckled Cocoyam (Colocasia esculenta (L.) Schott) slices: Optimisation of drying conditions for improved product quality and energy savings

Cited by 26 publications

References 41 publications

Investigating the Effect of Different Drying Strategies on the Quality Parameters of Daucus carota L. Using Dynamic Process Control and Measurement Techniques

Investigating the Effect of Different Drying Strategies on the Quality Parameters of Daucus carota L. Using Dynamic Process Control and Measurement Techniques

Impact of Process Parameters and Bulk Properties on Quality of Dried Hops

Quantitative analysis and visualization of moisture and anthocyanins content in purple sweet potato by Vis–NIR hyperspectral imaging

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