Effects of Cinnamon Leaves Residue Aqueous Extract on the Chemical, Physicochemical and Bioactive Properties of Yogurt

Cham, Xin Yee (2020) Effects of Cinnamon Leaves Residue Aqueous Extract on the Chemical, Physicochemical and Bioactive Properties of Yogurt. Final Year Project (Bachelor), Tunku Abdul Rahman University College.

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Abstract

Cinnamon is well known of its bioactivity owing to the phenolics-rich essential oil in it. However, most of the research is done on cinnamon bark and twig but not the leaves. Therefore, this study was conducted to explore the potential of cinnamon leaves as the source of bioactive compounds in yogurt. Different from other research, the cinnamon leaves used in this study are the by-product discharged after essential oil extraction. At the first stage of this study, the optimum extraction time of cinnamon leaves was determined by conducting extraction using hot water at 130oC for 1, 2 and 3 hrs. The total phenolic (TPC), flavonoid content (TFC), 2, 2-diphenyl-1-picrylhydrazyl free radical scavenging (DPPH) activity, Ferric Reducing Antioxidant Power (FRAP) and anti-inflammation (albumin denaturation inhibition activity, ADI activity) of cinnamon leaves water extract (CLE) were determined. The results obtained indicate that there was no significant differences (p>0.05) between TPC, TFC, DPPH and FRAP for the 3 extraction time. However, ADI activity of CLE dropped significantly after 3-hrs extraction. ADI activity of CLE at 1 and 2 hrs extraction was no significant difference (p>0.05) Therefore, CLE produced at 1 hr was selected to use in the subsequent study. Prior to addition into yogurt, CLE was encapsulated with 1% agar. However, encapsulation was found to reduce the free TPC, TFC, anti-oxidant and anti-inflammation activity of CLE. The free TPC, TFC, anti-oxidant and anti-inflammation activity of encapsulated CLE (labeled as EE) was lower than non-encapsulated CLE (labeled as E). The encapsulation efficiency of CLE was 90.29±0.80%. About 0.8% of E and EE was added into milk for yogurt fermentation. The pH, stability test (% of syneresis) and rotational viscosity were evaluated among control, E yogurt and EE yogurt after fermentation. Generally, pH of control yogurt was lower than E and EE yogurt. Furthermore, EE yogurt was found to be more stable than control and E yogurt. Nevertheless, the rotational viscosities of all types of yogurt was no significant different (p>0.05). Results of analysis revealed that enrichment of yogurt with E and EE successfully increased its TPC, TFC and anti-oxidant activity but not ADI activity. Results of FTIR analysis indicate that there is no chemical difference between control, E yogurt and EE yogurt. This result suggests that there were no new chemical linkages formed between the milk protein and compounds in E and EE during yogurt fermentation. The availability of chemical and bioactivity of yogurt was further investigated through in-vitro gastrointestinal digestion. Results of gastrointestinal digestion indicate that TPC, TFC and FRAP of E-/EE-yogurt were higher than plain yogurt (control) after gastric and intestinal digestion. However, DPPH of E yogurt was dropped to lower than control after gastrointestinal digestion. Nevertheless, DPPH of EE yogurt was remained higher than control. Surprisingly, ADI activity which was not detected in the yogurt increased substantially after gastrointestinal digestion. E yogurt possessed the highest ADI activity after digestion. Findings of this project proposed that CLE is an excellent functional ingredient for anti-oxidant and anti-inflammation. Extraction time did not affect the chemical and bioactive properties of CLE and the best extraction time was 1 hr. Encapsulation significantly influences the anti-oxidant and anti-inflammation activity of yogurt enriched with CLE. Future study should be conducted to optimize the encapsulation process so that both anti-oxidant and anti-inflammation of yogurt enriched with CLE could well preserved upon gastrointestinal digestion.