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A comparative study of infrared and microwave heating for microbial decontamination of paprika powder.

Eliasson L, Isaksson S, Lövenklev M, Ahrné L - Front Microbiol (2015)

Bottom Line: In the present experimental set-up microwave treatment at 98°C for 20 min resulted in a reduction of 4.8 log units of the total number of mesophilic bacteria, while the IR treatment showed a 1 log unit lower reduction for the corresponding temperature and treatment time.Microwave and IR heating created different temperature profiles and moisture distribution within the paprika sample during the heating up part of the process, which is likely to have influenced the decontamination efficiency.The results of this study are used to discuss the difficulties in comparing two thermal technologies on equal conditions due to differences in their heating mechanisms.

View Article: PubMed Central - PubMed

Affiliation: Food and Bioscience, SP Technical Research Institute of Sweden , Gothenburg, Sweden.

ABSTRACT
There is currently a need in developing new decontamination technologies for spices due to limitations of existing technologies, mainly regarding their effects on spices' sensory quality. In the search of new decontamination solutions, it is of interest to compare different technologies, to provide the industry with knowledge for taking decisions concerning appropriate decontamination technologies for spices. The present study compares infrared (IR) and microwave decontamination of naturally contaminated paprika powder after adjustment of water activity to 0.88. IR respectively microwave heating was applied to quickly heat up paprika powder to 98°C, after which the paprika sample was transferred to a conventional oven set at 98°C to keep the temperature constant during a holding time up to 20 min. In the present experimental set-up microwave treatment at 98°C for 20 min resulted in a reduction of 4.8 log units of the total number of mesophilic bacteria, while the IR treatment showed a 1 log unit lower reduction for the corresponding temperature and treatment time. Microwave and IR heating created different temperature profiles and moisture distribution within the paprika sample during the heating up part of the process, which is likely to have influenced the decontamination efficiency. The results of this study are used to discuss the difficulties in comparing two thermal technologies on equal conditions due to differences in their heating mechanisms.

No MeSH data available.


Related in: MedlinePlus

Thermal images of the paprika powder after IR heating for (A) 20 s, (B) 40 s, and corresponding images of microwave heating after (C) 20 s and (D) 40 s. Upper row of images are taken from above, and lower row are images taken of the cross-section of the paprika sample. In the first case the petri dish cover was removed after heating; in the latter case the petri dish was split with bottom and cover still in place.
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Figure 3: Thermal images of the paprika powder after IR heating for (A) 20 s, (B) 40 s, and corresponding images of microwave heating after (C) 20 s and (D) 40 s. Upper row of images are taken from above, and lower row are images taken of the cross-section of the paprika sample. In the first case the petri dish cover was removed after heating; in the latter case the petri dish was split with bottom and cover still in place.

Mentions: Thermal images were taken during the IR and microwave treatment after interruption of the process and removal of the samples from the IR or microwave oven. This was done to evaluate the heat distribution at two times of the heating-up phase. Based on the total 60 s heating-up time of microwave heating, a time step of 60/3 = 20 s was chosen, resulting in images at times 20 and 40 s, with reference images of IR heating at the same times. The resulting images are shown in Figure 3. The thermal images in the upper row of Figure 3 were taken from above the sample a few seconds after removal of the petri dish cover. The images of the cross-section (the lower row of thermal images) were taken a few seconds after splitting the petri dishes.


A comparative study of infrared and microwave heating for microbial decontamination of paprika powder.

Eliasson L, Isaksson S, Lövenklev M, Ahrné L - Front Microbiol (2015)

Thermal images of the paprika powder after IR heating for (A) 20 s, (B) 40 s, and corresponding images of microwave heating after (C) 20 s and (D) 40 s. Upper row of images are taken from above, and lower row are images taken of the cross-section of the paprika sample. In the first case the petri dish cover was removed after heating; in the latter case the petri dish was split with bottom and cover still in place.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4588691&req=5

Figure 3: Thermal images of the paprika powder after IR heating for (A) 20 s, (B) 40 s, and corresponding images of microwave heating after (C) 20 s and (D) 40 s. Upper row of images are taken from above, and lower row are images taken of the cross-section of the paprika sample. In the first case the petri dish cover was removed after heating; in the latter case the petri dish was split with bottom and cover still in place.
Mentions: Thermal images were taken during the IR and microwave treatment after interruption of the process and removal of the samples from the IR or microwave oven. This was done to evaluate the heat distribution at two times of the heating-up phase. Based on the total 60 s heating-up time of microwave heating, a time step of 60/3 = 20 s was chosen, resulting in images at times 20 and 40 s, with reference images of IR heating at the same times. The resulting images are shown in Figure 3. The thermal images in the upper row of Figure 3 were taken from above the sample a few seconds after removal of the petri dish cover. The images of the cross-section (the lower row of thermal images) were taken a few seconds after splitting the petri dishes.

Bottom Line: In the present experimental set-up microwave treatment at 98°C for 20 min resulted in a reduction of 4.8 log units of the total number of mesophilic bacteria, while the IR treatment showed a 1 log unit lower reduction for the corresponding temperature and treatment time.Microwave and IR heating created different temperature profiles and moisture distribution within the paprika sample during the heating up part of the process, which is likely to have influenced the decontamination efficiency.The results of this study are used to discuss the difficulties in comparing two thermal technologies on equal conditions due to differences in their heating mechanisms.

View Article: PubMed Central - PubMed

Affiliation: Food and Bioscience, SP Technical Research Institute of Sweden , Gothenburg, Sweden.

ABSTRACT
There is currently a need in developing new decontamination technologies for spices due to limitations of existing technologies, mainly regarding their effects on spices' sensory quality. In the search of new decontamination solutions, it is of interest to compare different technologies, to provide the industry with knowledge for taking decisions concerning appropriate decontamination technologies for spices. The present study compares infrared (IR) and microwave decontamination of naturally contaminated paprika powder after adjustment of water activity to 0.88. IR respectively microwave heating was applied to quickly heat up paprika powder to 98°C, after which the paprika sample was transferred to a conventional oven set at 98°C to keep the temperature constant during a holding time up to 20 min. In the present experimental set-up microwave treatment at 98°C for 20 min resulted in a reduction of 4.8 log units of the total number of mesophilic bacteria, while the IR treatment showed a 1 log unit lower reduction for the corresponding temperature and treatment time. Microwave and IR heating created different temperature profiles and moisture distribution within the paprika sample during the heating up part of the process, which is likely to have influenced the decontamination efficiency. The results of this study are used to discuss the difficulties in comparing two thermal technologies on equal conditions due to differences in their heating mechanisms.

No MeSH data available.


Related in: MedlinePlus