Functional lipid enriched dairy products geared towards obesity management
: technological feasibility and nutraceutical potential

Student thesis: Doctoral Thesis


The number of people afflicted by excess weight has been growing each year thus making obesity a worldwide public health problem. Furthermore, conventional treatment regiments (surgery or drug based) are of difficult access to the public and their results more often than note fall short of the desired effects. Thus, alteration of eating behaviours has become the main recommendation for obesity management as it is easier to implement, easier to access and has a wider reach for a larger number of citizens. Nowadays, one of the main dietary drawbacks is the high saturated fat content of some foodstuffs which creates various health problems. However, there are also some health benefits related with fat ingestion, as polyunsaturated ones are responsible for reducing cholesterol and triglycerides levels in blood. Considering this dichotomy this thesis main goal was to understand if it was possible to develop bioactive lipids rich dairy products capable of modulating or exerting a positive effect upon obesity related metabolism. To that end, the work was divided in 4 distinct stages. In stage one, three different vegetable oils (pomegranate, coconut, and avocado) were selected due to the differences in their fatty acids profile and posteriorly their chemical composition and biological potential was characterized. The data obtained showed that of the three oils pomegranate was richer in conjugated fatty acids (73% of the total fatty acids), coconut richer in medium chain fatty acids (60% of the total fatty acids) and, the avocado oil was an excellent source of monounsaturated fatty acids (80% of the total fatty acids). From a biological perspective, all three oils significantly reduced adipocytes’ lipid accumulation in (79% for pomegranate, 76% for avocado and 49% for coconut oil, respectively) and were capable of modulating gut cells’ inflammatory response, reducing IL-6 pro-inflammatory cytokine’ secretion (33% pomegranate oil, 22% coconut oil and 11% avocado oil). The addition of vegetable oil into foods has several challenges with one of them being their susceptibility to oxidation. For this reason, the second step of the work consisted in the development of a carboxymethyl cellulose (hydrophilic component) based bigel in conjunction with either Tween 80 or Geleol to protect the oil during processing and the gastrointestinal tract passage. It was found that the solution developed allowed to reduce the degradation of the main fatty acids of each oil throughout the gastrointestinal tract. On stage three, vegetable oils were incorporated into dairy products. The first approach consisted in their incorporation into yogurts either in its free or bigel form. The data obtained showed that oils addition did not negatively affect the yogurts rheological characteristics, however, the addition of coconut oil bigel impairs the yogurts visual appearance. In terms of nutritional profile, the oil’s addition led to a significant increase (over 50%) in their essential fatty acids content. Following the simulated digestion of the yogurts the data obtained showed that the digested samples reduced lipidic accumulation in hepatocytes (8 to 17% for the non-induced model and 30 to 40% for the steatosis induced model) and in adipocytes (23 to 25%), with the best performer being for the avocado oil yogurt (13% and 25%, respectively). The incorporation in bigel was not a valid alternative for pomegranate oil, as during the digestive process it showed a high fatty acids loss (64%). Thus, a chitosan-based microparticle (2% w/v) solution for incorporation of the pomegranate oil in yogurts was developed. This approach allowed for an increase in the amount of conjugated fatty acids that reached the intestine and, consequently, increase the yogurts bioactive potential. This was reflected in the yogurts capacity to modulate adipocytes metabolism, as seen by the reduction of 77% in leptin secretion while simultaneously increasing by 50% adiponectin levels, and in the reduction of pro-inflammatory cytokines secretion (IL-6 and TNF-α by 50% and 12%, respectively) in colon cells. As dairy products are among the most relevant and consumed products worldwide, a second development avenue, in the form of fresh cheese, was explored. In this approach in addition to the oil’s incorporation the produced products were supplemented with probiotic microorganisms (Lactiplantibacillus plantarum 299v e Bifidobacterium animalis Bo), as these have been shown to possess an important anti-obesogenic role. The data obtained showed that the fresh cheese was a better matrix than yogurt, as it presented a higher oil retention percentage and consequently a higher nutritional potential, due to the higher fatty acid content. Additionally, fresh cheeses showed a better bioactive potential than yogurts, particularly due to their higher capacity to reduce leptin secretion (87% for cheese vs 80% for yogurts). The fourth and final stage consisted in using the dairy product prototype (avocado oil bigel fresh cheese), which showed the highest bioactive potential, and perform in-depth studies using more complex cellular models. To do so, the amount of fatty acids (oleic and palmitic) capable of permeating through a simulated intestinal barrier (Caco-2/HT29-MTX co-culture) was evaluated and the permeated fatty acids’ modulation of adipocytes metabolism and macrophages inflammatory response was studied. The data showed that permeated fatty acids reduced leptin (8.7%) and the pro-inflammatory cytokines MPC-1 (96%) and IL-1β (78%) in adipocytes. Similarly, for macrophages a significant reduction of inflammatory response modulation was observed (60% in IL-6 secretion). In general, all prototypes developed could reduce lipidic accumulation in both hepatocytes and adipocytes, with the different fatty acids’ profiles leading to distinct modulation of adipokines secretion. Pomegranate yogurts showed an elevated capacity to reduce leptin secretion when in comparison with the coconut and avocado ones. However, this did not reflect itself in the adiponectin secretion as the increase registered was similar for the three oils. Similarly, to the adipocyte’s metabolism modulation the samples impact upon the macrophages inflammatory response also appeared to be lipidic profile dependent, with only the pomegranate oil yogurts being capable of reducing TNF-α secretion in LPS stimulated macrophages. On the other hand, all yogurts were capable of reducing IL-6 secretion. Considering the results obtained, the produced bioactive lipids functionalized dairy products showed promising anti-obesity results and potential to be used as viable food alternatives in obesity management and prevention.
Date of Award19 Apr 2023
Original languageEnglish
Awarding Institution
  • Universidade Católica Portuguesa
  • University of Aveiro
  • University of Minho
SponsorsFundação para a Ciência e a Tecnologia
SupervisorMaria Manuela Pintado (Supervisor), Ana Maria Gomes (Co-Supervisor) & Luís Miguel Rodríguez-Alcalá (Co-Supervisor)


  • Obesity
  • Fatty acids
  • Functional foods
  • Lipidic metabolism
  • Immunomodulatory capacity
  • Dairy products


  • Doutoramento em Ciência e Tecnologia Alimentar e Nutrição

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