Encapsulated CLA passes dairy taste test - study

Researchers from Mexico's Universidad Veracruzana and UNIDA-Instituto Tecnológico de Veracruz report that consumer tasting of milk, yogurt and butter revealed detection thresholds of 100, 200 and 300 mg of CLA per 100 g, respectively.

"According to these data, microcapsules can be added in concentrations smaller than 100, 200 and 300 mg of CLA per 100 g of milk, yoghurt and butter, respectively, without being detected," wrote the researchers in the journal LWT - Food Science and Technology .

CLA are found predominantly in dairy products such as milk, cheese and meat, and are formed by bacteria in ruminants that take linoleic acids - fatty acids from plants - and convert them into conjugated linoleic acids, or CLA.

Knowledge surrounding the health benefits of the acids has been increasing, with studies indicating potential benefits for weight management, bone health and possibly even cancer.

Fortification of dairy with the ingredient has been limited by stability issues that ultimately affect taste and consumer acceptance, said the researchers behind the new study.

"The conjugated bonds in CLA decrease the oxidative stability of the CLA, resulting in decreased nutritional quality and off-flavour development," wrote the researchers in the journal "CLA is easily oxidised and several studies have suggested that it must be protected until used as a fortifier or additive in foods," they added.

The researchers prepared microcapsules of CLA (75 per cent purity, Lipid Nutrition) in whey protein concentrate (four parts WPC to CLA, weight for weight), and added to milk, yoghurt and butter in varying concentrations.

Microcapsules are tiny particles that contain an active agent or core material surrounded by a shell or coating, and are now increasingly being used in food ingredients preparation.

A panel of ten tasters (average age 25, six women) evaluated the resulting products, and the threshold values determined.

Above the threshold, the panellists reported unpleasant aftertaste, rancid, acid and nutty flavours.

"The preference was 30, 40 and 60 for milk, yogurt and butter, respectively, supplemented with 100 mg of microencapsulated CLA," reported the researchers.

This result indicated that the CLA was more difficult to detect in butter, said the researchers.

"Consumer comments on CLA-supplemented dairy products will be useful in determining their commercial viability," stated the researchers.

Source: LWT - Food Science and Technology (Elsevier) Published on-line ahead of print, doi: 10.1016/j.lwt.2007.07.008 "Sensory evaluation of dairy products supplemented with microencapsulated conjugated linoleic acid (CLA)"

Authors: Maribel Jimenez, H.S. Garcia and C.I. Beristain