Effect of Simulated Gastrointestinal Digestion on Phytochemicals from Citrus-Derived Waste

Citrus is one of the most consumed fruit crops in the world, its peels are often discarded, contributing to environmental pollution. This study aims at extracting the bioactive compounds in these wastes and showing the possible effect of digestion on the type and amount of the phytochemicals present. Using maceration, five solvents (Acetone, dichloromethane, methanol, n-hexane and distilled water) were used for the extraction and the phytochemical detection and quantification were performed using reagent detection methods. Simulated gastro intestinal digestions were carried out on the extracts by mimicking the digestive process that occur in the stomach and the intestine invitro and the phytochemical analysis repeated. The results before the digestion showed the presence of all the phytochemicals assayed for in the methanol and distilled water extracts. Flavonoids were also seen to be present in the extracts obtained from all the solvents used. Varying amounts of the phytochemicals were obtained after the quantitative screening; flavonoids were found to have a higher amount than other secondary metabolites with 16.68±0.1mg/100g in distilled water and 14.72±0.86mg/100g in dichloromethane extracts. During digestion, changes in pH, viscosity, aroma and color were observed in both gastric and intestinal phases. Additionally, phytochemical screening after the digestion revealed the presence of alkaloids, flavonoids and tannins in the acetone extract. Flavonoids, phenols and tannins were present in dichloromethane extract, flavonoids and tannins were present in distilled water, whereas only tannin was present in methanol. None of the phytochemical was present in extract dissolved in N-hexane while saponin was absent in all the solvents after digestion. Quantitatively, the result showed varying amounts of the phytochemical in the extract with flavonoids in acetone and dichloromethane (1.94±0.01mg/100g) and tannins in methanol (1.95±0.01mg/100g) having the highest value while phenol in dichloromethane (1.61±0.41mg/100g) has the lowest value. The results obtained showed that digestion has affected the type and quantity of phytochemicals found in citrus-derived waste.