Benefits of once-a-day milking

Work carried out at Teagasc Moorepark suggests that once-a-day milking does not impact Cheddar cheese composition and can improve cheese yield and some sensory and nutritional attributes.

Until recently, limited work had been done to explore how dairy products are affected by milking frequency, but research by Teagasc into once-a-day milking (OAD) has shown no negative impact on cheese quality. 

OAD results in lower overall milk volume and milk solids yield than twice-a-day milking (TAD), yet interest in OAD systems is still growing. Approximately 200 dairy farms are operating OAD milking on a full-time basis in Ireland, and this number is expected to increase.

The main reasons for choosing OAD milking include farm layout, reduced milking time, improved farmer wellbeing, opportunities for other business activities and a reduction in labour costs. However, not all milk is equal and it is crucial to consider how changes in milking frequency might affect the nutritional and technical properties of milk as well as the quality of subsequent dairy products.

Researchers at Teagasc Moorepark investigated the effects of OAD milk on some of the major compositional, functional and sensory attributes of full-fat Cheddar cheese. Cheese is an economically important dairy product, with around one-third of all milk in Ireland segregated for cheese production. Any significant changes in cheese-associated altered milk composition linked to reduced milking frequency could have far-reaching implications for the dairy industry.

Richard Page (left) and Prabin Lamichhane cut milk gel as part of the process of making Cheddar cheese at Teagasc Food Research Centre, Moorepark

Methodology for ongoing study

The Animal and Grassland Research and Innovation Centre at Moorepark provided milk from OAD and TAD dairy herds. Raw bulk OAD milk had an average fat, protein and lactose content of 5.4%, 4.46% and 4.41%, whereas raw bulk TAD milk had 5.26%, 4.17% and 4.49% respectively.

OAD and TAD milks were converted to Cheddar cheese at Teagasc Food Research Centre in Moorepark. The milk was standardised to a protein-to-fat ratio of 0.95, and pasteurised at 72°C for 15 seconds prior to cheese making. 

Cheddar cheese from OAD and TAD milks were matured over 180 days, with compositional and functional analysis performed throughout the ripening period. While the analysis of these cheeses is ongoing, interesting insights into the effect of reduced milking frequency are already emerging.

Using OAD milk for cheese-making did not affect overall cheese composition. This is reassurance for cheese producers, should the practice of OAD milking garner wider uptake by farmers. Furthermore, cheese yield was higher from OAD milk than TAD per unit volume of standardised milk, linked to higher innate milk solids. From an efficiency perspective, this provides the added benefit of maximising cheese manufacturing capacity, using existing processing infrastructure.  

Sensory characteristics: texture and colour

It is possible to mimic consumer sensory and mouthfeel expectations through laboratory experiments based on texture profile analysis. The texture properties (hardness, cohesiveness, springiness, resilience) of OAD and TAD cheeses were not statistically different in this study. Based on these results, consumers should not detect significant differences in the mouthfeel of cheese made with OAD milk.

Colour is an important quality characteristic of food products, influencing consumer preference, taste perception and purchasing choice. Typically more highly coloured cheese is preferred by consumers, with OAD cheese more visually yellow, or richer in colour compared to TAD cheese.

Nutrition: β-carotene

β-carotene is an important provitamin – a plant pigment that the body converts to Vitamin A. In testing, it was found that β-carotene content in OAD cheese samples was significantly higher than TAD cheese. On average, OAD cheese contained 31% more β-carotene than TAD cheese.

Vitamin A (including β-carotene) is recognised for its numerous health benefits, which include supporting iron metabolism; maintaining of normal skin and mucous membranes; maintaining normal vision; and maintaining of the normal function of the immune system. This indicates that OAD milking could potentially offer additional nutritional benefits to cheese consumers, and this could be a unique opportunity for Irish cheese producers to differentiate their cheese internationally. However, more research is required to confirm this possibility.

True colours

The colour differences of cheese samples can be quantified objectively by colorimetric analysis.

The L* a* b* colour space is commonly used to identify colour differences in food samples:

• L* indicates lightness
• a* represents green to red
• b* represents blue to yellow.

Colorimetric analysis showed that OAD cheese samples were significantly yellower (higher b* value) than TAD cheese samples, linked to higher beta-carotene levels. Among the factors influencing consumer purchasing decisions, colour intensity of cheese remains a key attribute as it is linked to a perception of higher fat content and a richer product with improved sensory quality. More recently, the yellow colour of Irish dairy products has also been associated by consumers with grass-fed milk, and the associated benefits of that system from animal, nutritional and environmental perspective.

Acknowledgements

The contributors would like to thank Tom O’Callaghan (UCC) and Seamus O’Mahony (UCC) for their contribution to this research. Also, the contributors wish to thank Teagasc Animal and Grassland Research and Innovation Centre for managing the milking system and providing milk.

Funding

Teagasc internal funding. Project: Futuremilk2025. Richard Page is a recipient of a Teagasc Walsh Scholarship.

Contributors

Richard Page, Teagasc Walsh Scholar, Food Chemistry and Technology Department, Teagasc Moorepark, Fermoy, Cork.
John Tobin, Department Head, Food Chemistry and Technology Department, Teagasc Moorepark, Fermoy, Cork.
Michael O’Donovan, Department Head, Grassland Science, Teagasc, Moorepark, Fermoy, Cork.
Prabin Lamichhane, Research Officer, Food Chemistry and Technology Department, Teagasc Moorepark, Fermoy, Cork.

This article was first published in TResearch Spring 2023