Teagasc researchers are looking at a new starter culture for Cheddar cheese manufacturing. “Cheese ripening consists of a complex series of chemical and biochemical reactions that contribute to texture and flavour development. Many of these reactions are a result of bacterial activity during ripening. The bacterial flora of most varieties is complex, consisting of added starter strains, as well as an endogenous secondary flora, referred to as the non-starter lactic acid bacteria (NSLAB),” explains Dr John Hannon.
The Teagasc Food Research Centre at Moorepark has built an international reputation in cheese research covering safety, flavour and efficiency and supports the Irish cheese industry from the artisan producer to large companies. For example, in a recent issue of TResearch, Teagasc’s scientific magazine, Dr Hannon and Dr Tom Beresford describe the use of a new starter culture - Streptococcus thermophilus.
“Currently, Cheddar cheese starters are composed of several defined, well characterised Lactococcus lactis strains chosen for their acid-producing ability and high bacteriophage insensitivity (a bacteriophage is a virus that attacks bacteria). This has resulted in the use of an increasingly small number of lactococcal strains, which are expected to perform reliably within strict manufacturing schedules to produce consistent quality product,” says Dr Hannon. “However, the destructive potential of lactococcal phage, which reduces the rate of acid production, is detrimental in modern processing plants. Phage susceptibility can frequently emerge after extended use of cultures, leading to disruption of manufacturing schedules and reduction in product quality. The capacity of strains to impact on cheese flavour/aroma is derived from their ability to degrade proteins (proteolysis), carbohydrates (glycolysis) and lipids (lipolysis). However, differences in the presence and expression of genes involved in these biochemical pathways exist between bacterial strains and should be key criteria for consideration in strain selection”.
The Teagasc researchers have been looking at S. thermophilus from a biodiversity and also from a flavour point of view. “The key findings that S. thermophilus has the potential to impact on cheese flavour and quality is of very significant importance to commercial cheese manufacturers and culture supply companies. S. thermophilus, while not a traditional component of the starter system for Cheddar cheese manufacture, has achieved widespread application due to a number of favourable technological properties. The data generated in this project clearly demonstrates the potential of these strains to impact on cheese quality. The fact that a wide biodiversity of strains was demonstrated indicates that with correct strain selection it should be possible to identify strains that will suit the commercial objectives of different companies”, says Dr Hannon.
Researchers at the Teagasc Food Research Centre at Moorepark are hosting ‘The Eight Cheese Symposium Moorepark 2011’ this September, where industry and academia will come together to share experiences on the latest developments and applications of cheese research. The international conference will cover Flavour Development, Cheese Diversification, Health and Nutrition/Fat and Salt Reduction, and, Cheese: From Quality to Concepts.
“Research to capitalise on the increased opportunities for cheese manufacture resulting from an increased milk pool (40% by 2020 according to the Food Harvest 2020 report) must begin now. Advances in diversification, nutrition, reduced fat/salt, flavour and quality will help industry to ensure that it gains a considerable share of the increased market opportunity”, said Dr Hannon.