Inactivation Effect of Infrared Radiation Heating on Bacterial Spores Pretreated at Various Water Activities

Hamanaka, Daisuke; Uchino, Toshitaka; Furuse, Naomi; Tanaka, Shun Ichiro

doi:10.4265/bio.10.61

Cited by 7 publications

(4 citation statements)

References 17 publications

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“…The differences in the distribution of the water inside the IR respectively microwave treated sample could possibly have influenced the decontamination efficiency. This since previous studies show that the heat resistance of spores is related to the water activity, and its preservation, during heat treatment ( Hamanaka et al, 2005 ; Tiburski et al, 2014 ).…”

Section: Resultssupporting

confidence: 52%

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

Eliasson¹,

Isaksson²,

Lövenklev³

et al. 2015

Front. Microbiol.

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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.

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Section: Resultssupporting

confidence: 52%

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

Eliasson¹,

Isaksson²,

Lövenklev³

et al. 2015

Front. Microbiol.

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“…Oregano was conditioned to a w 0.88 before IR treatment. Increased a w has previously been demonstrated to improve the decontamination efficiency of B. cereus spores in spices (Staack and others ), and bacterial spores are known to be more heat resistant at the intermediate water activities (Fine and Gervais ; Hamanaka and others ) typical of dried herbs and spices. In addition, the increased moisture content facilitated faster and more homogenous IR heating of the oregano sample.…”

Section: Resultsmentioning

confidence: 99%

Infrared Decontamination of Oregano: Effects on Bacillus cereus Spores, Water Activity, Color, and Volatile Compounds

Eliasson

Libander

Lövenklev

et al. 2014

Journal of Food Science

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Infrared (IR) heating, a novel technology for decontaminating oregano, was evaluated by investigating the reduction of inoculated Bacillus cereus spores and the effect on water activity (a(w)), color, and headspace volatile compounds after exposure to IR treatment. Conditioned oregano (a(w) 0.88) was IR-treated in a closed heating unit at 90 and 100 °C for holding times of 2 and 10 min, respectively. The most successful reduction in B. cereus spore numbers (5.6 log units) was achieved after a holding time of 10 min at 90 °C, while treatment at 100 °C for the same time resulted in a lower reduction efficiency (4.7 log units). The lower reduction at 100 °C was probably due to a reduced aw (aw 0.76) during IR treatment or possibly to the alteration or loss of volatile compounds possessing antimicrobial properties. The green color of oregano was only slightly affected, while the composition of volatile compounds was clearly altered by IR heating. However, two of the key aroma compounds, carvacrol and thymol, were only slightly affected, compared to the effect on the other studied compounds, indicating that the typical oregano aroma can likely be preserved. In conclusion, IR heating shows potential for the successful decontamination of oregano without severe alteration of its color or the key aroma compounds, carvacrol and thymol.

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“…Sample preparation for inactivating treatment In order to investigate the characteristics of spore inactivation by single and sequential treatment of IR and UV, stainless steel Petri dishes (19×ϕ 90 mm) were used as reported in our previous studies (Hamanaka et al, 2005(Hamanaka et al, , 2006. A 2-mL sample of the prepared spore suspensions was inoculated onto a stainless steel Petri dish, spread evenly, and air-dried on a clean bench (MCV-710ATS, Sanyo Electric Co., Ltd., Osaka, Japan) at room temperature.…”

Section: Methodsmentioning

confidence: 99%

Effect of Combining Infrared Heating with Ultraviolet Irradiation on Inactivation of Mold Spores

Hamanaka

Atungulu²,

Tanaka

et al. 2010

FSTR

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Combining effect of infrared radiation (IR) heating with ultraviolet (UV) irradiation on the inactivation of mold spores isolated from citrus fruits was investigated. Fruit-related molds (Penicillium, Aspergillus, Cladosporium, Rhizopus, and Byssochlamys) were inoculated on stainless steel Petri dish and inactivated by IR heating, UV irradiation, and combined treatments with different sequence orders. Three isolates (Penicillium, Aspergillus and Cladosporium) were sensitive to IR heating, while Rhizopus and Byssochlamys spores were relatively sensitive to UV irradiation rather than IR heating. Combinations of IR heating with UV irradiation were effective in the inactivation of all mold spores. Considerable reductions in the survival of all mold spores were achievable by the combined treatment regardless of the treatment order.

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Inactivation Effect of Infrared Radiation Heating on Bacterial Spores Pretreated at Various Water Activities

Cited by 7 publications

References 17 publications

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

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

Infrared Decontamination of Oregano: Effects on Bacillus cereus Spores, Water Activity, Color, and Volatile Compounds

Effect of Combining Infrared Heating with Ultraviolet Irradiation on Inactivation of Mold Spores

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