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Kyung, Hyun‐,Kyu,Ramakrishnan, Sudha Rani,Kwon, Joong‐,Ho John Wiley & Sons 2019 Journal of the Science of Food and Agriculture Vol.99 No.2
<P><B>Abstract</B></P><P><B>BACKGROUND</B></P><P>Due to differences in radiation sources (electron beam from electron accelerator, gamma ray from <SUP>60</SUP>Co radionuclide) and energy delivery time (dose rate, kGy/time), the effects on foods are expected to be different with regard to chemical quality change and microbial decontamination. To better understand this impact, effects of variable dose rates of electron beam (EB, kGy s<SUP>−1</SUP>) and gamma rays (GR, kGy h<SUP>−1</SUP>) on microbial reduction, capsanthin content, and color parameters of red pepper (<I>Capsicum annuum</I> L.) powders (RPP) were determined. RPP samples were irradiated with 3 kGy absorbed dose, at variable dose rates of 1 and 5 kGy s<SUP>−1</SUP> of EB (10 MeV/10 kW), and 1.8 and 9 kGy h<SUP>−1</SUP> of GR (<SUP>60</SUP>Co).</P><P><B>RESULTS</B></P><P>Aerobic plate counts (APC) as well as yeast and mold counts of non‐irradiated samples were 7.12 log CFU g<SUP>−1</SUP> and 6.62 log CFU g<SUP>−1</SUP>, respectively. EB and GR reduced these by 2–3 log CFU g<SUP>−1</SUP>. A lower dose rate (1 kGy s<SUP>−1</SUP>) of EB was more effective for microbial reduction than a higher dose rate (5 kGy s<SUP>−1</SUP>). In contrast, a higher dose rate (9 kGy h<SUP>−1</SUP>) of GR efficiently decreased APC compared to a lower dose rate (1.8 kGy h<SUP>−1</SUP>). Higher EB and GR dose rates significantly decreased the capsanthin content and Hunter's red color (<I>a</I>* value).</P><P><B>CONCLUSION</B></P><P>Low EB (kGy s<SUP>−1</SUP>) and high GR (kGy h<SUP>−1</SUP>) dose rates are recommended for microbiological safety of RPP with negligible changes in color attributes visible to the human eye, in contrast to the measured values. Thus the study demonstrates that the influence of absorbed dose is dependent on the applied dose rates. © 2018 Society of Chemical Industry</P>
Kim, Gui-Ran,Ramakrishnan, Sudha Rani,Kwon, Joong-Ho Pergamon 2018 Radiation physics and chemistry Vol.152 No.-
<P><B>Abstract</B></P> <P> <I>Saengshik</I> products usually include powders of plant-derived foods that are normally non-heated and thus have inherent limitations in microbial control. Here, we investigated the microbial reduction and sensorial properties of two types of <I>Saengshik</I> products commercially available in Korean markets after electron-beam and gamma-ray irradiation (0, 1, 3, 5, and 10 kGy). The initial microbial loads in the products were 6–7 log colony-forming units (CFU)/g of total aerobic bacteria (TAB), 4–5 log CFU/g of yeasts and molds (YM), and ≤ 3 log CFU/g of coliforms. Radiosensitivities (D<SUB>10</SUB> values) of TAB, YM, and the indicator pathogens <I>Clostridium perfringens</I> and <I>Bacillus cereus</I> were 1.21–1.86 kGy, 1.03–1.97 kGy, 0.42–0.48 kGy and 0.58–0.68 kGy, respectively, regardless of the radiation source or product type. Radiation 5D values for both pathogens were 2.10–3.40 kGy, which is the dose needed to achieve the recommended 5-log reduction. The radiation sensitivity (D<SUB>10</SUB> and 5D values) was higher in <I>B. cereus</I> than in <I>C. perfringens</I> for both samples. Irradiation up to 10 kGy induced negligible changes in sensory scores for the <I>Saengshik</I> samples (p > 0.05). An electronic nose effectively distinguished the flavor profiles of irradiated products between 10 kGy and ≤ 5 kGy approved by the Korean Food Code for <I>Saengshik</I> ingredients. These results indicate that 5 kGy irradiation with electron-beam or gamma-ray was sufficient for achieving microbial control in powdered <I>Saengshik</I> products.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Radiosensitivity of microorganisms in <I>Saengshik</I> products was studied. </LI> <LI> Irradiation > 9 kGy is needed for 5-log decrease in aerobic bacteria, yeasts, and molds. </LI> <LI> D<SUB>10</SUB> values of <I>C. perfringens</I> and <I>B. cereus</I> were 0.48 and 0.68 kGy, respectively. </LI> <LI> Dose up to 10 kGy induced negligible changes in sensory attributes of <I>Saengshik</I>. </LI> </UL> </P>
Antibacterial, and antioxidant potentials of non-cytotoxic extract of <i>Trichoderma atroviride</i>
Saravanakumar, Kandasamy,Chelliah, Ramachandran,Ramakrishnan, Sudha Rani,Kathiresan, Kandasamy,Oh, Deog-Hwan,Wang, Myeong-Hyeon Elsevier 2018 Microbial pathogenesis Vol.115 No.-
<P><B>Abstract</B></P> <P> <I>Trichoderma</I> species are a rich source of metabolites, but less known for biomedical potential. This work deals with antibacterial and antioxidant potentials of intracellular non-cytotoxic metabolites, extracted from <I>Trichoderma atroviride</I> (KNUP001). A total of 53 fractions was collected by column chromatography and tested for cytotoxicity by MTT assay. Only one fraction (F41) was found to be non-toxic to Vero cells with 95.4 ± 0.61% of survival. The F41 was then subjected to chemical analysis, antibacterial and antioxidant assays. The F41 at 500 μg ml<SUP>−1</SUP> showed the total antioxidant of 48.70 ± 2.90%, DPPH radical scavenging activity of 37.25 ± 2.25, nitric oxide (NO) radical scavenging activity of 54.55 ± 1.95 and H<SUB>2</SUB>O<SUB>2</SUB> radical scavenging activity of 43.75 ± 3.21. The F41 at 25 μg ml<SUP>−1</SUP> displayed antibacterial activity against <I>E. coli</I> (14.25 ± 0.25 mm)<I>, Proteus mirabilis</I> (10.40 ± 0.60 mm), and <I>Enterobacter aerogenes</I> (5.60 ± 0.40 mm). GC-MS analysis revealed the dominant presence of oleic acid C 18.1 (63.18%), n-hexadecanoic acid (6.17%), and ethyl oleate (4.93%) in the F41, and hence these fatty acids are likely responsible for the antioxidant and antibacterial activities of F41. Hence, further investigation deserves on purification and characterization of the active metabolites from <I>T. atroviride</I> strain KNUP001 towards developing molecular leads to effective antibacterial drugs, and non-toxic to host cells.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Non-cytotoxic metabolites extracted from <I>Trichoderma atroviride</I>. </LI> <LI> Potential antibacterial and antioxidant activity credited to the synergic effect of non-cytotoxic metabolites. </LI> <LI> Fatty acids, oleic acid C 18.1, n-hexadecanoic acid, and ethyl oleate are the dominant presence in non-cytotoxic metabolites. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>