Nuclear Science and Technology, Vol. 3. No. 4 (2013), pp. 29-32
Stiufy on decontamination of microorganisms in garlic powder by gamma Co-60 radiation
Vo Thi Kim Lang, 'Nguyen Thuy Khanh, ^Doan Thi The, "Nguyen Thi Tu Trinh Research and Development Center for Radiation Technology. Vietnam Atomic Energy Institute
202A, street]], Linh xuan Ward, Thu due District, Ho Chi Minh City, Vietnam 'Uiuversity of Technical Education, Ho Chi Minh City
Email: vtklangOJ^yahoo.com (Received 21 November 2013, accepted 27 Februar\" 2014)
Abstract Garlic powder was irradiated by gamma-rays from a Co-60 source to reduce microbial contamination for prolong the storage and preservation time. Results showed that the initial microbial number of about lO^CFU/g contaminated in garlic powder was exceeded for the set standard of TCVN 7809 - 2007 and ISO 5560 - 1997. The total aerobic bacteria and yeast mold cells of irradiated garlic powder were reduced &om 10*CFU/g to 10\ 6x10^ and 6x10" CFU/g at doses of 0, 4, 8 and 12 kGy, respectively. The level of microbial contamination was significantly reduced by irradiation at 4 kGy but it is only appropriate for domestic acceptance. At the irradiation doses of 8 and 12 kGy, the level of microbial contamination was fiirther reduced after storage for two months and it is appropriate to export. In addition, the irradiated garlic powder was in good quality with no change of moisture, oil content and sensory properties. Thus, gamma Co-60 irradiation is a very effective method for reducing the number of microbial contaminated in garlic powder.
Keyword; Garlic powder, decontamination, microorganism, gamma Co-60 radiation.
L INTRODUCTION Garlic {Altiumsativum L) belongs to AUiaceac plant species. Garlic was known for long time not only as spice but also as miracle natural drug. In Vietnam, several famous garlic growing areas are Ly Son island, Quang Ngai province, Phu Qui, Binh Thuan province. Ha Bac and Hai Himg province. Typically, Ly son garlic is well known owing to unique aroma and specifically gentle sharp taste. In recent years, growing of garlic gained high benefit with the average production of 350 tons/year and turnover of about 125,000 million VND.
In general, exported products especially garlic powder fece with strong competition by oversea products. Market of Europe, USA.
Japan and so on requested the export companies of Viemam to follow the strict standards on micoorganisms and insect contamination set by authority organization such as APHIS. USA. In Vietnam, processing
C2013 Viemam Atomic Energy Societ;
of garlic after harvest is still preliminary treatment process. In the tropical climate, some spice products such as pepper, chili, garlic,...
commonly contaminated high bioburden that caused damage to the quality of product and subsequently to the growers.
Food uradiation is a processing technology applied to assure the sanitary safety of food. At the present time, there is 30 countries worldwide applied this technology for processing of more than 40 different kinds of food such as fiijits, cereals, meat and other agricultural and seafood products.
Due to wholesomeness as well as economic benefit of irradiated food. World Health Organization (WHO), Food and Agriculture Organization (FAQ) and International Atomic Energy Agency (IAEA) approved irradiation method for processing of food as same as hot and cold temperature treatment. Irradiation is effective method for quarantine control and prevention of and Vietnam Atomic Energy Institute
STUDY ON DECONTAMINATION OF MICROORGANISMS IN GARLIC POWDER .
7 • 6 •
foodbom diseases as well as reducing the economic effectiveness.
n. EXPREMENTAL A. Matoials and diemicals: Garlic powder used in the experiment was supplied by Anh long Company in Ho Chi Minh City. PCA (plate count agar), a medium for aerobic bacteria and SDA (sabouraud dextrose agar), a medium for yeast and mold cell are products of Himedia, Indian.
B. Method
Sample preparaticm: Garlic powder was collected from different containers for sampling and ften packaged in PE bag with lOOg/bag for gamma irradiation and storage at ambient temperature.
bradi^on treatment: Garlic powder samples were irradiated by gamma Co-60 radiation at dose of 0 (conti-ol), 4, 8 and 12 kGy as respective symbols of MO, M4, M8 and MI2 at Co-60 irradiator of VINAGAMMA center, Ho Chi Minh City with dose rate of - 1 kGy/h.
Irradiated samples were stored at ambient temperature for 60 days.
Decontammatian eSci&icy: Microorganism contamination is based on number of count forming unit per 1 g sample (CFU/g) and sterile peptone solution according to TCVN 5165-90 [5].
Detimunation of moisture and oQ coa^t: Oil content is determined by steam distillation of gariic powder [5].
Saisory test: Based on orientation pair test (double side test) [5,6]. Data were statistically analyzed using the ANOVA (analysis of variation) test with mean value and standard error with the p-value less than 0.05.
m. RESULTS AND DISCCUSION A. Effect of dose on total aerobic bacteria contaminaticm
Fig. L Effect of dose and storage time on total aerobic bacteria contamination Resuhs in Fig 1 showed that the average number of total bacteria on garlic powder was reduced to 2, 3 and 4 log compared to that of control sample (MO) for dose of 4, 8 and 12 kGy, respectively. It indicated that the higher the dose the lower the number bacteria remained on gariic sample. However, for control sample after two months of storage, the number of aerobic bacteria was slightly reduced (see Fig. 1), it may be due to some active substances such as allicinin in garlic powder inhibited the growth of bacteria [1].
B. Effect of dose and storage time on total number of yeast and mold cell
14 30 44 Time, day Fig. 2. Effect of dose and storage time o
yeast and mold cell
number of 30
v o THI KIM LANG, NGUYEN THUY KHANH. DO AN THI THE, NGUYEN THI TU TRINH Results in Fig. 2 indicated that after 60
days stored at ambient temperature, the contamination of yeast and mold cell decreased to 2, 3 and 4 log for doses of 4, 8 and 12 kGy, respectively compared to that of control sample. Thus, radiation processing method is effective to reduce the microorganisms contamination for food namely for garlic compared with other methods [7,8].
C. Effect of dose storage time on oil content Table L Effect of dose and storage time on oil content
Sample MO M4 M8 M12
Oil content (%) 0.0165*± 0.0088 0.0149'± 0.0038 0.0158"± 0.0127 0.0153'± 0.0102 Means values followed by the same letter within a column are not statistically different with p<0. OS.
Results in table I indicated that oil content of irradiated garlic samples were not significantly changed compared to that of control one. The obtained results also indicated that irradiation of garlic powder did not affect to oil content during storage [6].
D. Effect of dose and storage time on moisture content
14 30 44 60
Fig. 4. Effect of radiation dose and storage time on moisture content
Result in Fig. 4 showed that the moisture content of irradiated samples (M4, M8, Ml2) after 60 days storage at ambient temperature did not significant change in compared with control sample (MO). The moist content was also satisfied to standard TCVN 7809:2007 and ISO 5560: 1997 (not higher than 8%).
E. Effect of dose and storage time on sensory qualities of garlic powder
Table E. Grade of sensory properties after 60 days storage
Sample MO,,,,, M8,606, LSDo 05
Color 0.6' 0.4' 0.2
Taste 0.45*
0.55' 0.1 Means values followed by the same letter within a column are not statistically different with p<0.05.
The ANOVA results on color and taste values of garlic powder during storage in Table II showed that sensory properties on color and flavor for 8 kGy irradiated and control (0 kGy) garlic powder samples assessed by consumers was not significantly different.
IV. CONCLUSIONS Original garlic powder has high number of contaminated microorganisms that is not satisfied for domestic and export market standard. Irradiation processing of garlic powder significantly reduced the contamination particularly to reduce 4 log at 8 kGy. Irradiation treatment did not affect the moisture and oil content as well as sensory properties of garlic powder. Irradiation at 8-12 kGy. the gariic powder is satisfied the set standard for export. Gamma irradiation of garlic powder is considered as effective and suitable processing method for decontamination and prolongation especially in our country condition of tropical climate.
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