Effect of pasture versus indoor feeding systems on quality characteristics, nutritional composition, and sensory and volatile properties of full-fat Cheddar cheese.

Discipline: cheese; Key words: pasture, total mixed ration, Cheddar cheese, fatty acid.

The composition of the diet can influence the chemical composition of milk and dairy products. In particular, the difference is noticeable between pasture fed systems and TMR diets. To what extent it influences the eventual composition of products such as cheese has not been quantified properly. This then was the topic of the study of Dr Tom O’Callaghan and colleagues in Ireland. The objective was to investigate the effects of pasture-based versus indoor TMR feeding systems on the chemical composition, quality characteristics and sensory properties of full-fat Cheddar cheeses. The results of their study were published in the Journal of Dairy Science, Volume 100 of 2017, page 6053 to 6073, with the title: Effect of pasture versus indoor feeding systems on quality characteristics, nutritional composition, and sensory and volatile properties of full-fat Cheddar cheese.

The researchers divided 54 multiple and first lactation Friesian cows into three groups for the entire lactation period. Group 1 was housed indoors and fed a TMR diet of grass and maize silage plus concentrates; Group 2 was kept outdoors on perennial ryegrass and Group 3 was also kept outdoors on perennial ryegrass/white clover pasture. Full-fat Cheddar cheeses were manufactured in triplicate at pilot scale from each feeding system in early autumn and were evaluated over a 270 day ripening period at 8⁰C.

The results showed that the pasture feeding systems produced Cheddar cheeses yellower in colour than the Cheddar cheeses from the TMR system, which was correlated with the higher ß-carotene in the pastures. Feeding system also had a significant effect on the fatty acid composition of the cheeses. The nutritional composition of the Cheddar cheeses was improved through pasture feeding, implicating a lower thrombogenicity index score and a greater than two-fold increase in the concentration of vaccenic acid and the bio-active conjugated linoleic acid C18:2 cis-9, trans-11, whereas TMR-derived cheeses had a significantly higher palmitic acid content. By comparing the fatty acid profile of the cheeses, a clear distinctive pattern could be established between pasture-based diets (both pasture types) and the TMR system. Physically this resulted in pasture-based derived cheeses having reduced hardness scores at room temperature. Furthermore, feeding system and ripening time had a significant effect on the volatile profile of the cheeses, the pasture-derived cheeses having had higher concentrations of the hydrocarbon toluene and the TMR-derived cheeses a higher concentration of 2,3-butanediol. With regard to ripening, the ripening period resulted in significant alterations in cheese volatile profiles with increases in acid-, alcohol-, aldehyde-, ester- and terpene-based volatile compounds.

In conclusion: This study has demonstrated the benefits of pasture-derived feeding systems for production of Cheddar cheeses with enhanced nutritional and physical properties if compared with TMR-derived Cheddar cheeses.