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The effects of sonication and gamma irradiation on the inactivation of Escherichia coli and Saccharomyces cerevisiae in pomegranate juice.

Alighourchi H, Barzegar M, Sahari MA, Abbasi S - Iran J Microbiol (2014)

Bottom Line: The serious concern over unprocessed fruit juices is microbial contamination, which effectively inactivated by thermal processing, but it significantly affects juice functional compounds.The results showed that lower amplitude levels (50 and 75%) did not inactivate E. coli and S. cerevisiae significantly (<1.5 log reduction), while at 100% amplitude level for 15 min, their population reduced by 3.47 and 1.86 log cfu/mL, respectively.Further research is needed to determine the effect of these methods on other fruit juices for industry purposes.

View Article: PubMed Central - PubMed

Affiliation: Department of Food Science and Technology, Faculty of Agriculture, Tarbiat Modares University, Tehran, Iran.

ABSTRACT

Background and objectives: Pomegranate fruit is a rich source of bioactive compounds. The serious concern over unprocessed fruit juices is microbial contamination, which effectively inactivated by thermal processing, but it significantly affects juice functional compounds. Therefore, the effect of gamma irradiation and ultrasonic on inoculated microbial to pomegranate juices was studied.

Materials and methods: Two pomegranate cultivars were purchased from the Agricultural Research Center of Saveh, and their juices were extracted by a manual device and immediately centrifuged. Then the studied microorganisms were re-suspended in sterile pomegranate juices. The juices were continuously sonicated at amplitude levels of 50, 75 and 100% and times of 0, 3, 6, 9, 12 and 15 min at temperature of 25 ± 1 °C. Irradiation treatment was also carried out at various doses of 0, 0.5, 1.0, 1.5, 2.0, 2.5 and 3 kGy.

Results: The results showed that lower amplitude levels (50 and 75%) did not inactivate E. coli and S. cerevisiae significantly (<1.5 log reduction), while at 100% amplitude level for 15 min, their population reduced by 3.47 and 1.86 log cfu/mL, respectively. Gamma irradiation treatment at 1 kGy also reduced E. coli by 6.66 log cfu/mL, whereas at 3 kGy it reduced S. cerevisiae by 5.08 log cfu/mL.

Conclusions: The low-dose gamma irradiation could potentially inactivate the studied microorganisms compared to the sonication, which had less destructive effects on their populations. Further research is needed to determine the effect of these methods on other fruit juices for industry purposes.

No MeSH data available.


Related in: MedlinePlus

Survival curve of E. coli at ultrasound amplitude levels of 50 (●), 75 (■) and 100 (▲) in Malase Momtaze Saveh arils (MMSA, 1) and Alak Saveh arils (ASA, 2) juices.
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Figure 1: Survival curve of E. coli at ultrasound amplitude levels of 50 (●), 75 (■) and 100 (▲) in Malase Momtaze Saveh arils (MMSA, 1) and Alak Saveh arils (ASA, 2) juices.

Mentions: The inactivation of both microorganisms at lower amplitude levels of 50 and 75% were not considerable (< 2log reduction), while a log cfu/mL reduction was achieved at the lethal amplitude level (100%) and 15 min that reduced E. coli and S. cerevisiae populations by 3.37-3.56 log cfu/mL and 1.84-1.88 log cfu/mL, respectively (Figs. 1 & 2). There was a noticeable and similar reduction trend among pomegranate juices, especially in the E. coli population, whereas the reduction rate of S. cerevisiae population in the treated samples was different, so that the D-values of these microorganisms in MMSA and ASA samples at 75% intensity were significantly different. In addition, the results showed that E. coli compared with S. cerevisiae in the sonicated pomegranate juice had a greater log reduction indicating its lower resistance to ultrasonic when suspended in pomegranate juices. The results demonstrated that the pH of pomegranate juices had no significant effect on E. coli and S. cerevisiae inactivation.


The effects of sonication and gamma irradiation on the inactivation of Escherichia coli and Saccharomyces cerevisiae in pomegranate juice.

Alighourchi H, Barzegar M, Sahari MA, Abbasi S - Iran J Microbiol (2014)

Survival curve of E. coli at ultrasound amplitude levels of 50 (●), 75 (■) and 100 (▲) in Malase Momtaze Saveh arils (MMSA, 1) and Alak Saveh arils (ASA, 2) juices.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4419047&req=5

Figure 1: Survival curve of E. coli at ultrasound amplitude levels of 50 (●), 75 (■) and 100 (▲) in Malase Momtaze Saveh arils (MMSA, 1) and Alak Saveh arils (ASA, 2) juices.
Mentions: The inactivation of both microorganisms at lower amplitude levels of 50 and 75% were not considerable (< 2log reduction), while a log cfu/mL reduction was achieved at the lethal amplitude level (100%) and 15 min that reduced E. coli and S. cerevisiae populations by 3.37-3.56 log cfu/mL and 1.84-1.88 log cfu/mL, respectively (Figs. 1 & 2). There was a noticeable and similar reduction trend among pomegranate juices, especially in the E. coli population, whereas the reduction rate of S. cerevisiae population in the treated samples was different, so that the D-values of these microorganisms in MMSA and ASA samples at 75% intensity were significantly different. In addition, the results showed that E. coli compared with S. cerevisiae in the sonicated pomegranate juice had a greater log reduction indicating its lower resistance to ultrasonic when suspended in pomegranate juices. The results demonstrated that the pH of pomegranate juices had no significant effect on E. coli and S. cerevisiae inactivation.

Bottom Line: The serious concern over unprocessed fruit juices is microbial contamination, which effectively inactivated by thermal processing, but it significantly affects juice functional compounds.The results showed that lower amplitude levels (50 and 75%) did not inactivate E. coli and S. cerevisiae significantly (<1.5 log reduction), while at 100% amplitude level for 15 min, their population reduced by 3.47 and 1.86 log cfu/mL, respectively.Further research is needed to determine the effect of these methods on other fruit juices for industry purposes.

View Article: PubMed Central - PubMed

Affiliation: Department of Food Science and Technology, Faculty of Agriculture, Tarbiat Modares University, Tehran, Iran.

ABSTRACT

Background and objectives: Pomegranate fruit is a rich source of bioactive compounds. The serious concern over unprocessed fruit juices is microbial contamination, which effectively inactivated by thermal processing, but it significantly affects juice functional compounds. Therefore, the effect of gamma irradiation and ultrasonic on inoculated microbial to pomegranate juices was studied.

Materials and methods: Two pomegranate cultivars were purchased from the Agricultural Research Center of Saveh, and their juices were extracted by a manual device and immediately centrifuged. Then the studied microorganisms were re-suspended in sterile pomegranate juices. The juices were continuously sonicated at amplitude levels of 50, 75 and 100% and times of 0, 3, 6, 9, 12 and 15 min at temperature of 25 ± 1 °C. Irradiation treatment was also carried out at various doses of 0, 0.5, 1.0, 1.5, 2.0, 2.5 and 3 kGy.

Results: The results showed that lower amplitude levels (50 and 75%) did not inactivate E. coli and S. cerevisiae significantly (<1.5 log reduction), while at 100% amplitude level for 15 min, their population reduced by 3.47 and 1.86 log cfu/mL, respectively. Gamma irradiation treatment at 1 kGy also reduced E. coli by 6.66 log cfu/mL, whereas at 3 kGy it reduced S. cerevisiae by 5.08 log cfu/mL.

Conclusions: The low-dose gamma irradiation could potentially inactivate the studied microorganisms compared to the sonication, which had less destructive effects on their populations. Further research is needed to determine the effect of these methods on other fruit juices for industry purposes.

No MeSH data available.


Related in: MedlinePlus