Split defect and secondary fermentation in Swiss-type cheeses – A review

Abstract

Split and secondary fermentation defects in Swiss-type cheese varieties are manifested as undesirable slits or cracks that may lead to downgrading of the cheese. Split defect is associated with an excessive production of gas or an unsuitable cheese body that cannot accommodate gas produced, or a combination of both factors. Secondary fermentation is the apparent production of gas after the desired propionic fermentation of the warm room has taken place. No consensus exists as to the definitive causes of the defects, but possible causes are reviewed under factors that are associated with rheological behaviour (including cheese manufacture, acidification, intact protein content and proteolysis, seasonality of milk supply and ripening or storage temperature and duration) or with overproduction of gas (including milk microflora, propionic acid bacteria (PAB) — in particular strains with high aspartase activity and ability to grow at low temperatures, lactic acid bacteria, interactions between starter bacteria, facultatively heterofermentative lactobacilli (FHL) and other sources of gas including butyric acid fermentation). The influence of other parameters such as copper concentration, air incorporation, salt content, rind formation and cheese wrapping materials is also considered. Methods to reduce the prevalence of the split defect and secondary fermentation include addition of water to improve elastic properties by the removal of unfermented carbohydrate and the use of FHL to control PAB activity to prevent the production of excessive gas.