SYNERGISTIC EFFECT OF PRESSURE, TEMPERATURE AND pH ON INACTIVATION OF BACILLUS SUBTILIS SPORES IN BUFFER AND MODEL FOOD SYSTEMS

Abstract

The combined pressure‐thermal‐pH influence on inactivation of Bacillus subtilis ATCC 6633 spores (1 × 108 cfu/mL initial count) in citrate‐phosphate buffer was studied over a range of pressure (690 and 827 MPa), process temperature (60, 65, 70 and 75C), pH (3, 5 and 7) and pressure‐holding time (up to 10 min) combinations. The influence of food matrix effect on spore inactivation was studied using tomato puree (pH 4.05) and minced crabmeat (pH 7.25) samples. All the experiments were conducted using a pilot‐scale high‐pressure food processor. Increase in process temperature, pressure and pressure‐holding time increased spore inactivation. Further, the substrate pH and the food substrate also had a significant influence on the spore inactivation. The highest inactivation (≥7 log10 units) was obtained when the spores suspended in pH 3 buffer were processed at 827 MPa–75C for 5 min. Adjusting the product formulation by adjusting its pH can be used as an effective tool in enhancing spore lethality during high‐pressure processing. PRACTICAL APPLICATIONS High‐pressure processing with or without the addition of heat has been used effectively as commercial food pasteurization method for a variety of value‐added food products. The current study will help further the development of high‐pressure processed high‐acid or acidified food products.

The development of high hydrostatic pressure processes as an alternative to other pathogen reduction methods

“…1994; Sojka and Ludwig 1997; Ahn and Balasubramaniam 2007; Ratphitagsanti et al. 2009), (v) the food composition (Gao and Ju 2007a, 2010; Balasubramanian and Balasubramaniam 2010), (vi) the role of the nutrient receptors at the surface of the spores (Wuytack et al. 2000; Black et al.…”

“…2005), (vii) the pH value and other processing parameters (Stewart et al. 2000; Balasubramanian and Balasubramaniam 2010).…”

“…Over the last years, several studies have been carried out to investigate the factors that may influence the spores germination and inactivation (Zhang and Mittal 2008) such as: (i) the sporulation conditions (Raso et al 1998;Margosch et al 2004), (ii) the role of the temperature during the high-pressure process (Oh and Moon 2003;Cléry-Barraud et al 2004;Reddy et al 2006;Wilson et al 2008), (iii) the impact of the pressure value (Wuytack et al 1998), (iv) the pressure application process parameters (Hayakawa et al 1994;Sojka and Ludwig 1997;Ahn and Balasubramaniam 2007;Ratphitagsanti et al 2009), (v) the food composition Ju 2007a, 2010;Balasubramanian and Balasubramaniam 2010), (vi) the role of the nutrient receptors at the surface of the spores (Wuytack et al 2000;Black et al 2005), (vii) the pH value and other processing parameters (Stewart et al 2000;Balasubramanian and Balasubramaniam 2010).…”