A cross-over randomized study published in the British Journal of Nutrition (2016) tried to assess whether microencapsulated bitter compounds are effective in reducing human energy intake and appetite.
Several studies have demonstrated that bitter compounds can reduce human appetite and energy intake (EI) through the secretion of hormones in the gastrointestinal (GI) tract, activated by the bitter receptors. However, the use of bitter compounds as food ingredients is very limited due to their bitter taste, so a new study encapsulated bitter compounds with a coating made of ethyl cellulose and stearic acid. These capsules were then administered to healthy volunteers to investigate the effect of microencapsulated bitter compounds on human EI and appetite.
A total of twenty healthy subjects were selected from the Department of Agricultural Sciences of the University of Naples who participated in two experimental sessions. The exclusion criteria included: a BMI≥25kg/m2, chronic illnesses, prescription medications, smoking, dieting or recent loss of weight, pregnancy or lactation. An aqueous extract of G. lutea root (known to have a very bitter taste) was chemically characterized by HPLC analysis to determine the amount of bitter compounds and then it was coated with ethylcellulose and stearate coating. Two vanilla puddings, a microencapsulated bitter ingredient enriched pudding (EBIP) – with 8% of microencapsulated bitter ingredient (EBI) – and a control pudding (CP) were prepared. Both puddings had the same macronutrient composition and energy values and a preliminary test confirmed that the two puddings can not be distinguished from each other. These puddings were served together with three biscuits as breakfast to the subjects who were fasting on the experimental days.
Appetite sensations, glycemia and blood samples of the subjects were collected before the breakfast and at the intervals of 30, 60, 120 and 180min after breakfast. A self-selected lunch was served to the subjects three hours after breakfast and subjects were allowed to take as much time as needed to consume the food. EI was measured by difference between the amount of food taken and left by each subject in their plate. The subjects also filled out a food diary for all the foods and beverages they consumed for the following 24 hours. Biochemical and statistical analysis were performed.
The results from the in vitro digestion and the electron microscopy analysis of the two puddings confirmed the stability of EBI during the salivary phase and its breakdown along the GI tract. The results showed that the subjects who had EBIP at breakfast compared with CP, had a 10% reduction in EI at lunch and a 30% reduction during the post-lunch, with an overall 22% reduction in EI during the 24 hours after breakfast. No signiﬁcant differences between the two experimental breakfasts were found for the blood glucose level or any of the investigated hormones. The study results were comparable with a previous study by Janssen et al., for the gastric administration of bitter compounds into mice which reported a 49% reduction in 24-hour food intake in mice administered bitter compounds as compared to placebo. The strength of this study was the use of microencapsulated bitter compounds possessing a taste-masking effect prevented any adverse GI events or nausea in volunteers and inﬂuenced their eating behaviour following EBIP. The limitation of the study was the uncertainty of whether the study results can be applied to real life since the study only included two experimental sessions.
Overall the study results showed that microencapsulation is an effective approach to mask the bitterness of bitter compounds and for a targeted delivery to the intestine. As well, they showed that bitter compounds can reduce the EI and appetite in humans.
Written By: Hummara Aslam, MSc