Cheese late blowing

Bactofugation, a process based on centrifugal separation of bacteria and their spores, is practiced in the Netherlands. Since the spores of lactate-fermenting Clostridia (butyric acid bacteria) are removed, there is less risk that Gouda cheese will develop the late blowing defect caused by the metabolism of these bacteria (Van den Berg et al 1980). 

Consumer resistance to the use of synthetic additives in foods has stimulated interest in natural additives and preservatives. The principal natural additive used in cheese is the bacteriocin, nisin. Bacteriocins are peptides which inhibit a limited range of bacteria, usually closely related to the producer organism. The potential of nisin, produced by Lactococcus lactis, as a food preservative was first demonstrated using nisin-producing cultures in the manufacturer of Swiss-type cheese to prevent spoilage by Clostridia (Hirsch et ai, 1951). To date, nisin is the only purified bacteriocin commercially exploited as a food preservative. It can be added to processed cheese products to prevent late blowing by Clostridia, the spores of which, if present in the natural cheese, survive pasteurization (Barnby-Smith, 1992). 

Nitrate is used to a great extent as a preservative for the prevention of unwanted gas formation from coliforms and Clostridia. Nitrate acts as a hydrogen acceptor for coliforms as it is reduced to nitrite. Formation of gaseous hydrogen is thus prevented and this avoids early blowing of the cheese. Nitrite, in turn, inhibits the outgrowth of Clostridia bacteria and therefore late blowing of the cheeses is prevented. 

Nitrate is usually added to the milk for some varieties of cheese. It is reduced to nitrite which inhibits the growth of Clostridium spp. responsible for late gas blowing and flavor defects. Nitrite is rapidly destroyed in cheese so that the finished product contains only trace levels which pose no hazard to consumers. The contribution by cheese to the total intake of nitrite is negligible (Renner, 1987). 

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