Year: 2019
Type: dissertation
Abstract: Lipophilic functional compounds should be incorporated into lipid-based delivery systems, such as oil-in-water (O/W) emulsions, to overcome at least part of the challenges that limit their effectiveness.These bioactive molecules can interact with the other ingredients of the emulsion, altering its structure and of the system.In this context, the objective of this work was to understand how the interactions among emulsion ingredients can affect its applicability as a protection and delivery system, aiming the production of systems using the ingredient engineering approach.The ingredients used were β-carotene (bioactive), mixture of whey protein (WPI) and Tween 80 (T80) as emulsifiers and the oily phase was composed by sunflower oil (long chain triacylglycerol -LCT) or NEOBEE® 1053 (medium chain triacylglycerol -MCT).Initially, the relationship between the composition and structure of emulsions was evaluated from the effect of WPI-T80 blend and the oil type (LCT or MCT).Emulsions with LCT showed higher droplet size than MCT-emulsions.The curves of interfacial tension of LCT-and MCT-systems showed differences in the decay rate of tension over time, due to characteristics of the oil phase (hydrophobicity, unsaturation degree, presence of impurities) and the different proportions of each emulsifier within WPI-T80 blend.A stronger viscoelastic interface was observed in LCT emulsions mainly stabilized by WPI molecules.WPI is more resistant to the displacement when adsorbed onto more hydrophobic LCT surface (competitive adsorption phenomenon).MCT-interface with a higher T80 concentration was less viscoelastic due to an easier replacement of WPI by T80.These results showed that the interfacial layer composition was dependent on the WPI-T80 ratio and the oily phase features.The combination of T80 and WPI resulted in emulsions with better stability than emulsions stabilized by only protein, but a lower concentration of synthetic compound was used.In the next step, emulsions were submitted to in vitro digestion.Emulsions with higher WPIconcentration showed flocculation and coalescence of droplets in the stomach step, resulting in droplets with lower interfacial area for lipase action in the intestine.However, the replacement of Tween 80 by WPI up to 0.5% (w/w) was efficient to avoid aggregation of droplets under gastric conditions and produce emulsions with similar characteristics to those stabilized only with Tween 80.The MCT hydrolysis was not affected by the interfacial composition, but it was influenced by the chain size of free fatty acids (FFAs).LCT-emulsion stabilized only with WPI showed higher release rate of FFAs, but the replacement of 0.5%WPI by 0.5%T80 did not influence the amount of released FFAs.In this protein-surfactant ratio, WPI and Tween 80 acted together and achieved an improved performance during the gastric and enteric phases.In the last step, emulsions with addition of β-carotene were submitted to the simulated gastrointestinal conditions.The -carotene changed mean droplet size and potential of the fresh emulsions and after gastric step.The interfacial composition in LCTsystems did not affect amount of soluble -carotene in the micellar phase and digesta.The carotene entrapped within protein-coated MCT droplets was more stable to chemical degradation than that encapsulated in MCT-systems stabilized by WPI-T80 blend or pure T80.The -carotene interacted with the other ingredients of the O/W emulsions, which affected it stability and solubility within mixed micelles.In conclusion, the rational design of emulsified foods should be based on the choice of ingredients and knowledge of the interaction between them.
Author: Andresa Gomes Brunassi
Institution: Universidade Estadual de Campinas (UNICAMP)
Language: English
Topic: Proteins in Food Systems
Subfield: Food Science
Domain: Life Sciences
Open Access status: gold
OpenAlex ID: W4388857368