Korean Journal of Food Science and Technology (한국식품과학회지)

Korean Society of Food Science and Technology (한국식품과학회)
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Screening of Sterilized Ramen Soup by DEFT/APC Method and Its Quality Properties as Affected by Irradiation

DEFT/APC 측정에 의한 시판 분말수프의 살균처리여부 확인 및 감마선 처리에 따른 품질특성 평가

  • Published : 2009.10.31
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Abstract

The DEFT (direct epifluorescent filter technique)/APC (aerobic plate count) test was utilized to screen powdered Ramen soup samples (RS-1, RS-2) whether or not they have been microbial-decontaminated. The initial microbial loads of commercially-packaged samples were log DEFT 6.46 (RS-1) and 7.05 (RS-2), but the viable bacterial counts were log APC 2.74 (RS-1) and 1.95 (RS-2), respectively; this finding showed that they have been already decontaminated by methods other than irradiation. The same samples were then subjected to gamma irradiation at 0, 5 and 10 kGy in order to evaluate the microbial and physicochemical changes during post-irradiation storage for 6 months under room conditions ($10{\pm}3^{\circ}C$). The DEFT count was constant in irradiated samples even at different doses, but APC decreased with dose increases; this implies that the log DEFT/APC increased in a linear fashion with dose. No coliforms, yeasts and molds were detected in any of the samples, whereas the initially detected aerobic bacteria ($5.49{\times}10^2CFU/g$) were inactivated by 5 kGy or more and no growth was observed during the subsequent storage period. The pH of RS-1 was reduced by irradiation (p<0.01), but increased (p<0.01) with increasing storage time. Irradiation induced a reduction in volatile basic nitrogen (VBN), whereas an increase in thiobarbituric acid (TBA) values was observed. The storage time proved more influential than irradiation up to 10 kGy in terms of changes in the VBN and Hunter’s color values of powdered Ramen soups.

시판 라면분말수프(RS-1, RS-2)의 사전 위생화 처리여부를 알아보기 위하여 DEFT(direct epifluorescent filter technique)/APC (aerobic plate count) 측정을 실시한 결과, 사전 살균처리가 이루어진 제품임을 확인하였다. 시료의 초기 존재했던 균수인 log DEFT는 RS-1 6.46, RS-2 7.05를 보이면서 조사선량에 따라 거의 변화가 없었으나 총 생균수인 log APC는 RS-1 2.74와 RS-2 1.95를 보이면서 조사선량의 증가에 따라 감소하였으며 이로써 log DEFT/APC 값은 점차 증가하는 경향이었다. 또한 사전 살균여부가 알려지지 않을 경우 방사선에 의해 위생화 처리될 수 있음을 감안, 5 및 10 kGy의 감마선 조사에 따른 미생물학적, 이화학적 품질을 실온($10{\pm}3^{\circ}C$)에서 6개월 저장 중 평가하였다. DEFT count는 조사선량에 무관하게 일정한 범위의 값을 보여주었으나 생균수(APC)는 조사선량에 따라 유의적으로 감소하였다. 본 시료에서는 대장균군과 효모 및 곰팡이는 검출되지 않았으며, 초기 호기성 세균은 5 kGy 이상에서 사멸되었고 실온 저장 6개월 동안 뚜렷한 생육이 없었다. 라면수프 RS-1은 조사선량에 따라 pH가 감소하였고(p<0.01) 저장 중에는 증가하는 경향을 보였다(p<0.01). 조사선량의 증가로 라면수프의 VBN 함량은 감소하는 경향을, TBA가는 증가하는 경향을 보였으며, VBN 함량과 기계적 색도는 10 kGy까지의 감마선 조사에는 비교적 안정적이었으나 저장 조건의 영향을 더 크게 받는 것으로 나타났다.

Keywords

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