An Olive Leaves-Based Diet Might Improve Sheep's Cheese

Adding olive leaves to the diet of sheep might improve their health, increase the sus­tain­abil­ity of the food chain and cre­ate a bet­ter qual­ity cheese. The antiox­i­dant qual­i­ties of the olive leaves seem to migrate to cheese pro­duced from the sheep’s milk. Adding olive leaves might also improve the fatty pro­file of the cheese.

According to a study pub­lished in the International Dairy Journal, adding a feed­ing com­prised of 28 per­cent olive leaves to a sheep’s daily diet might pro­duce a health­ier-than-nor­mal cheese that con­sumers appre­ci­ate. The group of Italian researchers con­ducted the study by manip­u­lat­ing the diet of the sheep for thirty days.

Twenty mul­ti­parous Comisana ewes at mid-lac­ta­tion were divided into a con­trol group, and a leaves group. Both groups grazed together. During the two daily milk­ings, the leaves group would be given a con­cen­trate con­tain­ing dried olive leaves while the con­trol group ate the usual pel­leted con­cen­trate.

The results showed that the cheese made from the leaves group con­tained a higher per­cent­age of healthy fatty acids while the sat­u­rated fat per­cent­ages were sig­nif­i­cantly less than the con­trol group. Interestingly, the leaves group’s milk yield was also greater than the con­trol group.

According to the researchers, the leaves group’s cheese also had more cheese fat con­tent. Its pro­file, though, showed higher lev­els of monoun­sat­u­rated fatty acids.

The increased n‑3 polyun­sat­u­rated fatty acids in the leaves group’s cheese reduced the athero­genic and throm­bo­genic indexes and increased per­ox­id­abil­ity but not the hydroper­ox­ide con­tent. While vit­a­mins and cho­les­terol did not dif­fer between the groups, the researchers found vary­ing antiox­i­dant con­cen­tra­tions in the result­ing cheese.

After a rest period of 60 days, an untrained panel of con­sumers was asked to eval­u­ate both groups’ cheese. The panel mem­bers did not notice any rel­e­vant dif­fer­ences dur­ing their first blind tast­ing. After being told about the organolep­tic char­ac­ter­is­tics of the leaves group’s cheese, the panel indi­cated a greater appre­ci­a­tion for it than the con­trol group’s cheese.

Introducing their research, the sci­en­tists noted how both olive cul­ti­va­tion and sheep farm­ing are impor­tant activ­i­ties in the Mediterranean Basin. About 98 per­cent of olive oil and 46 per­cent of sheep milk orig­i­nate from the area.

Increasing num­bers of olive leaves are dis­carded dur­ing olive trans­for­ma­tion every year. The mech­a­niza­tion of the har­vest­ing oper­a­tion has been shown to cre­ate a ten­fold increase in olive leaf bio­mass.

On top of this, the researchers noted that olive leaves are suit­able food for sheep and explained that the process of incor­po­rat­ing olive leaves into sheep feed is quite sim­ple. As an added bonus, the leaves are car­ri­ers of cru­cial bioac­tive com­pounds, such as phe­nols, toco­pherols and carotenoids.

“The results pre­sented in this study indi­cated that inclu­sion of olive leaves in the diet of graz­ing lac­tat­ing sheep improved yield, antiox­i­dant capac­ity and fatty acid pro­file in a model cheese,” the researchers wrote in their con­clu­sion.

“In addi­tion, the con­sumer test revealed that the gen­eral sat­is­fac­tion increased after informed tast­ing only for the exper­i­men­tal cheese,” they wrote.

“Therefore, our find­ings sug­gest that the use of agro-indus­trial by-prod­ucts, besides rep­re­sent­ing an inter­est­ing strat­egy to improve ani­mal prod­uct qual­ity and food chain sus­tain­abil­ity, could be a valu­able strat­egy to add value to ani­mal food prod­ucts,” they con­cluded.

• Dietary olive leaves improve the qual­ity and the con­sumer pref­er­ences of a model sheep cheese