Microbial Inactivation by High Pressure

Purpose The increased demand for high-quality, nutritionally rich processed food has led to non-thermal food processing technologies like high pressure processing (HPP), a novel process for microbial inactivation with minimal loss of nutritional and sensory properties. The purpose of this paper is to highlight the impact of HPP on the microbiological, nutritional and sensory properties of food. Design/methodology/approach Recent research on the role of HPP in maintaining food quality and safety and the impact of process conditions with respect to various food properties have been explored in this paper. Also, the hurdle approach and the effectiveness of HPP on food quality have been documented. Findings HPP has been verified for industrial application, fulfilling the consumer demand for processed food with minimum nutrition loss at low temperatures. The positive impact of HPP with other treatments is known as the hurdle approach that enhances its impact against microorganism activity and minimizes the effects on nutrition and sensory attributes. Originality/value This paper highlights the impact of HPP on various food properties and a good alternative as non-thermal technology for maintaining shelf life, sensory properties and retention of nutrients.

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Non-Thermal Preservation of Fruit Juices

ASME 2008 Citrus Engineering Conference ◽

10.1115/cec2008-5404 ◽

2008 ◽

Author(s):

V. M. (Bala) Balasubramaniam

Keyword(s):

United States ◽

High Pressure ◽

Electric Field ◽

Food Industry ◽

Pulsed Electric Field ◽

The United States ◽

High Pressure Processing ◽

Fruit Juices ◽

Microbial Inactivation ◽

Juice Processing

Consumers demand healthier fresh tasting foods without chemical preservatives. To address the need, food industry is exploring alternative preservation methods such as high pressure processing (HPP) and pulsed electric field processing. During HPP, the food material is subjected to elevated pressures (up to 900 MPa) with or without the addition of heat to achieve microbial inactivation with minimal damage to the food. One of the unique advantages of the technology is the ability to increase the temperature of the food samples instantaneously; this is attributed to the heat of compression, resulting from the rapid pressurization of the sample. Pulsed electric field (PEF) processing uses short bursts of electricity for microbial inactivation and causes minimal or no detrimental effect on food quality attributes. The process involves treating foods placed between electrodes by high voltage pulses in the order of 20–80 kV (usually for a couple of microseconds). PEF processing offers high quality fresh-like liquid foods with excellent flavor, nutritional value, and shelf life. Pressure in combination with other antimicrobial agents, including CO2, has been investigated for juice processing. Both HPP and PEF are quite effective in inactivating harmful pathogens and vegetative bacteria at ambient temperatures. Both HPP and PEF do not present any unique issues for food processors concerning regulatory matters or labeling. The requirements are similar to traditional thermal pasteurization such as development of a Hazard Analysis Critical Control Point (HACCP) plan for juices and beverages. Examples of high pressure, pasteurized, value added products commercially available in the United States include smoothies, fruit juices, guacamole, ready meal components, oysters, ham, poultry products, and salsa. PEF technology is not yet widely utilized for commercial processing of food products in the United States. The presentation will provide a brief overview of HPP and PEF technology fundamentals, equipment choices for food processors, process economics, and commercialization status in the food industry, with emphasis on juice processing. Paper published with permission.

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Main factors regulating microbial inactivation by high-pressure homogenization: Operating parameters and scale of operation

Chemical Engineering Science ◽

10.1016/j.ces.2008.10.002 ◽

2009 ◽

Vol 64 (3) ◽

pp. 520-532 ◽

Cited By ~ 89

Author(s):

Francesco Donsì ◽

Giovanna Ferrari ◽

Ermelinda Lenza ◽

Paola Maresca

Keyword(s):

High Pressure ◽

Microbial Inactivation ◽

Operating Parameters ◽

High Pressure Homogenization ◽

Main Factors ◽

Scale Of Operation

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Effects of high pressure homogenisation of raw bovine milk on alkaline phosphatase and microbial inactivation. A comparison with continuous short-time thermal treatments

Journal of Dairy Research ◽

10.1017/s0022029906001853 ◽

2006 ◽

Vol 73 (4) ◽

pp. 454-463 ◽

Cited By ~ 63

Author(s):

Laëtitia Picart ◽

Maryse Thiebaud ◽

Malika René ◽

Joseph Pierre Guiraud ◽

Jean Claude Cheftel ◽

...

Keyword(s):

High Pressure ◽

Alkaline Phosphatase ◽

Micrococcus Luteus ◽

Bovine Milk ◽

Microbial Reduction ◽

Microbial Inactivation ◽

Thermal Treatments ◽

Globule Size ◽

Whole Milk ◽

Short Time

Raw whole milk of high microbial quality ([les ]4×104 cfu/ml) was processed using a ~15 l/h homogeniser with a high pressure (HP) valve immediately followed by cooling heat exchangers. The effects of homogenisation between 100 and 300 MPa (HP valve) with an initial milk temperature Tin=4 °C or 24 °C was investigated on the inactivation of: (i) endogenous alkaline phosphatase (ALP); (ii) endogenous milk flora and (iii) two Gram positive (Listeria innocua and Micrococcus luteus) and one Gram negative (Pseudomonas fluorescens) strains inoculated into milk. Temperatures T1 and T2 measured before and immediately after the HP valve, and fat globule size distributions were also determined. ALP activity slightly decreased after homogenisation above 250 MPa when Tin=4 °C (corresponding T2>58 °C), but markedly decreased above 200 MPa when Tin=24 °C (T2>60 °C). In contrast to inactivation induced by continuous short-time thermal treatments, ALP inactivation induced by HP homogenisation was clearly due to mechanical forces (shear, cavitation and/or impact) in the HP valve and not to the short ([Lt ]1 s) residence time at temperature T2 in the same valve. Inactivation of the three exogenous microorganisms led to similar conclusions. Homogenisation at 250 MPa or 300 MPa (Tin=24 °C) induced a 2–3 log cycle reduction of the total endogenous milk flora and a 1·5–1·8 log cycle reduction of inoculated List. innocua. Higher reduction ratios (2–4 log cycles) were obtained for the two other microorganisms. The highest levels of ALP inactivation corresponded to the highest extents of microbial reduction. Running the milk twice or three times through the homogeniser (recycling), keeping temperature T1≈29 °C and pressure=200 MPa, increased homogenisation efficiency.

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