Effects of Combined Hurdles (pH, Water Activity and Atmosphere) on Bacillus cereus Inactivation Using Cooked Rice Medium

การศึกษาผลของเทคโนโลยี Hurdle ต่อการยับยั้งเชื้อจุลินทรีย์ Bacillus cereus โดยใช้การปรับค่าความเป็นกรดด่าง ค่าปริมาณน้ำอิสระ และสภาวะบรรยากาศในผลิตภัณฑ์ข้าวหุงสุก

Name: Wisan Anggurarat

Organization : King Mongkut's University of Technology Thonburi. Faculty of Engineering. Food Engineering

keyword: Controlled Atmosphere

; การควบคุมบรรยากาศ

Abstract: The objective of this research was to investigate the effects of combined hurdles (pH, a, and controlled atmosphere) on B. cereus survival in rice-based medium. The experiments were divided into 3 parts. The first part concerned with the B. cereus growth in Nutrient Broth; cells at 8 hours were used to represent the cell in their stationary phase. The second part of the experiments was the study the growth of B. cereus in different cooked rice-base media (pure cooked rice, 10 percent of cooked rice in distilled water and 10 percent of cooked rice in Nutrient Broth). The growth character of B. cereus in 10 percent of cooked rice in distilled water treatment was similar to that of the pure cooked rice treatment, but highly facilitated the manipulation of hurdle parameter adjustment. Therefore, 10 percent of cooked rice in distilled water was selected as the cultivation medium in subsequent tests. The final part of the study was to investigate the effects of combined hurdles, controlled atmosphere (air, percentage of C02 in N2 at 0, 20 and 50), pH (4, 5, 6 and 7) and water activity (0.93, 0.95, 0.97 and 0.99), on B. cereus inactivation in the cooked rice medium. The results of pH stress showed that the pH values of less than or equal to 5 were able to terminate the growth of B. cereus. At pH of 6 and 7 the inactivation results varied depending on the other hurdles applied. For the effect of water activity it was found that at low a, and low pH the growth of B. cereus was hampered and the effectiveness of C02 treatment was more pronounced; the differences between the 20 and 50 percent of C02 treatments were also minimized. Combination of three hurdles had a significant impact on the inactivation of B. cereus in cooked rice medium. The results of this study form the basis of the future applications of these hurdle treatments and for the explanation of the growth of B. cereus in other rice-based media.

King Mongkut's University Technology Thonburi. Library

Address: กรุงเทพมหานคร (Bangkok)

Email: info.lib@mail.kmutt.ac.th

Name: Aluck Thipayarat

Role: Advisor

Created: 2004

Issued: 2007-12-17

Modified: 2009-01-29

วิทยานิพนธ์/Thesis

CallNumber: FDE269

eng

DegreeName: Master of Engineering

Level: Master's Degree

Descipline: Food Engineering

Grantor: King Mongkut's University of Technology Thonburi

©copyrights King Mongkut's University of Technology Thonburi

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