Development of a novel functional yogurt containing anti-inflammatory bioactive compounds : a thesis submitted in partial fulfilment of the requirements for the degree of Master of Food Technology, Massey University, Albany, New Zealand

Abstract

The consumption of bioactive compounds is increasingly becoming popular due to their beneficial effects on health and wellbeing. The anti-inflammatory properties of bioactives such as curcumin are well established. However, curcumin has low bioavailability, hence it is frequently consumed in capsules to enable the delivery of the required dosage to achieve optimum health benefits. Synergistic effects may be achieved by combining curcumin with other anti-inflammatory bioactive compounds. Recent investigations on lupeol and chlorogenic acid (CGA) have reported that these bioactive compounds show similar therapeutic benefits to curcumin. Furthermore, delivery of bioactives via a food matrix, such as fermented coconut yogurt, may improve bioavailability. Thus, this research investigated the potential of an anti-inflammatory combination of curcumin with CGA or lupeol with the objective of developing coconut yogurt to deliver the combined bioactives to humans. This research was performed in two parts. In part 1, the anti-inflammatory potential of three bioactive compounds (curcumin, CGA and lupeol), individually and in combination, was investigated using an in vitro model of human THP-1 macrophages stimulated with LPS. Differentiated THP-1 cells were treated with variable concentrations of curcumin, CGA and lupeol and their effects on the production of TNF-α, a pro-inflammatory cytokine, and cell viability was measured using ELISA and MTT assays, respectively. Curcumin alone significantly (p≤0.05) suppressed TNF-α production in a dose dependent manner. Curcumin in combination with lupeol gave an additional 15-35 % reduction in TNF-α level. However, the reduction in TNF-α production by curcumin + lupeol was accompanied by cell death. In contrast, treatment with CGA appeared to protect the THP-1 cells from LPS toxicity and its co-administration with curcumin at a 1:1 ratio reduced TNF-α production without impacting cell viability. Further, it is proposed that the latter combination showed anti-inflammatory activity by reducing mRNA expression of pro-inflammatory cytokines and COX-2 enzyme via suppressing NF-κB, IκB-β-kinase and TLR-4 receptor. Thus, a 1:1 combination of curcumin with CGA was selected to be delivered in coconut yogurt. In part 2, coconut yogurt enriched with turmeric and coffee to deliver the benefits of curcumin and CGA, respectively, was developed. Addition of 100 mg of each bioactive compound to 150 g coconut cream did not have any significant (p≤0.05) effect on the viable cell counts of the yogurt culture, pH and titratable acidity during fermentation. However, slight changes in pH, titratable acidity, viable cell counts and colour were noted during refrigerated storage of the yogurt for 15 days; no changes in syneresis was observed in the control and bioactive added samples. By the end of the storage period, 63.31±3.20 % and 84.81±3.17 % of curcumin and CGA, respectively, were retained in the yogurt samples. The yogurt samples with added bioactive compounds were well accepted by consumer sensory evaluation panellists. Thus, from the obtained data it can be concluded that coconut yogurt may be a potential delivery medium for health promoting curcumin and CGA to consumers.