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Microbial inactivation kinetics in soymilk during continuous flow high-pressure throttling
Vijendra Sharma1, Rakesh K Singh, Romeo T Toledo
1Dept. of Food Science and Technology, Univ. of Georgia, Athens, GA 30602, USA.
Journal of Food Science
|September 3, 2009
Summary
Clostridium sporogenes spores show increased thermal resistance in soymilk compared to peptone water. High-pressure throttling effectively reduces microbial populations in soymilk, with higher pressure and temperature enhancing sporicidal effects.
Area of Science:
- Food Microbiology
- Food Processing Technology
Background:
- Clostridium sporogenes spores exhibit significant thermal resistance, posing challenges for microbial inactivation in food products.
- Soymilk's composition can influence the heat resistance of microbial spores.
Purpose of the Study:
- To determine the thermal resistance of Clostridium sporogenes PA 3679 ATCC 7955 spores in soymilk and peptone water.
- To evaluate the efficacy of continuous flow high-pressure throttling (HPT) for microbial inactivation in soymilk.
Main Methods:
- Capillary tube method for determining thermal resistance (D-values and z-values).
- Continuous flow high-pressure throttling (HPT) at varying pressures (207-276 MPa), holding times, and temperatures (85-145°C).
Main Results:
- C. sporogenes spores demonstrated approximately 3-fold higher D(121)-values and significantly higher z-values in soymilk compared to 0.1% peptone water.
- HPT reduced microbial populations in soymilk by up to 6 log cycles.
- Increased pressure, time, and temperature during HPT enhanced the sporicidal effect, with lower pressures causing more spore injury and higher pressures causing cell death.
Conclusions:
- Soymilk enhances the thermal resistance of C. sporogenes spores, necessitating adjusted processing parameters for effective inactivation.
- Continuous flow HPT is a promising technology for reducing microbial load in soymilk, with optimized conditions crucial for maximizing sporicidal efficacy and minimizing spore injury.
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