Inhibitory Activity of Phosphates on Molds Isolated from Foods and Food Processing Plants

Abstract

Six commercial phosphates were evaluated for inhibition of the growth of 17 molds isolated from food sources. The assays were performed at neutral and natural (without pH adjustment) pH values, and the molds were streaked on plate count agar with added phosphates. Phosphate concentrations of 0.1, 0.3, 0.5, 1.0, and 1.5% (wt/vol) were used, and the MIC was determined. The resistance of molds to phosphates depended on the species. At a neutral pH, Aspergillus ochraceus and Fusarium proliferatum were resistant to all phosphates at all concentrations assayed, and Byssochlamys nivea, Aureobasidium pullulans, and Penicillium glabrum were most sensitive. The most inhibitory phosphates were those with chain lengths greater than 15 phosphate units and the highest sequestering power. At natural pH values (resulting from dissolving the phosphate in the medium), inhibitory activity changed dramatically for phosphates that produced alkaline or acidic pH in the medium. Phosphates with alkaline pH values (sodium tripolyphosphate of high solubility, sodium tripolyphosphate, and sodium neutral pyrophosphate) were much more inhibitory than phosphates at a neutral pH, but sodium acid pyrophosphate (acidic pH) had decreased inhibitory activity. The results indicate that some phosphates could be used in the food industry to inhibit molds linked to food spoilage.

Effects of Phosphates and Salt in Ground Raw and Cooked Farmed Cod (Gadus morhua) Muscle Studied by the Water Holding Capacity (WHC), and Supported by 31P‐NMR Measurements

“…In the European Union the upper limit for addition of tri‐ or polyphosphates (expressed as P 2 O 5 ) for fish intended for sale as frozen or for some processed seafood products is 5 g phosphates/kg (European Parliament and Council 2006), which is in the range explored in this study. In addition to the potential improvements in quality of precooked portions, several studies indicate an inactivating effect (on the lytic cycle, and in complexing essential metal ions for cell growth) of phosphates as microbiological inhibitors during storage as well as in heat treatment (Ellinger 1972b; Suàrez and others 2005; Borch and Lycken 2007; Suàrez and others 2007). It was also interesting to note the positive effect on WHC of salt even at the low levels as applied here (0.3% to 1% in the sample), a similar range to that observed, that is, in fish stored in ice slurries (Larsen and Elvevoll 2008) and thus beneficial to shelf life as well as yield.…”

Polyphosphates as inhibitors of surface mould growth on hard cheese during ripening

“… b Percentage of micro‐organisms out of total of 17 moulds isolated from food products (Suárez et al. 2005).…”

“…Furthermore, a semiquantitative evaluation of antifungal activity was made, considering the observation of mould growth in five sections (1 cm 2 ) of cheese surface for each treatment. The criterion adopted for the expression and interpretation of the results was: ()) absence of mould growth in all 1 cm 2 sections, (+) mould growth on <50% in all 1 cm 2 sections, (++) mould growth on 50-75% in all 1 cm 2 sections and Percentage of micro-organisms out of total of 17 moulds isolated from food products (Suárez et al 2005). The assays were performed using the same polyphosphate for immersion and coated and the polyphosphates crossed (different polyphosphates for immersion and coated).…”

“…There is evidence that polyphosphates could interfere with certain stages of mould metabolism, such as cell differentiation, sporulation and production of toxins and antibiotics (Molins 1991). In our previous work (Suárez et al 2005), it was demonstrated that, as happens with bacteria, phosphates with the most effective inhibitory power were those with a chain length higher than 15 phosphate units.…”

Antibacterial effects of commercially available phosphates on selected microorganisms

“…Antimicrobial eff ects of phosphates are described mainly in gram-positive bacteria, some mi cro mycets and yeast cells (Knabel et al, 1991;Zaika and Kim, 1993;Lee et al, 1994a;Loessner et al, 1997;Suarez et al, 2005Suarez et al, , 2007. The inhibitory eff ect on grampositive bacteria is dependent on the chain length (level of condensation) of phosphates.…”